Datsun engined Imp. What was that?!!....

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yoeddynz
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Re: 1965 Datsun engined Imp. First drive!!!!

Post by yoeddynz » Sun May 19, 2019 7:22 pm

oli wrote:Great job all round. Still think it should have an Imp engine in it though!

Well done, when are you starting number two?
(No proper Imp owner ever has just one Imp!)

Keep up the good work.
Oh I do love the imp engines. However the first imp I bought that got me started down this resto came fitted with the Datsun and is certed and legal as such. They might not be as light but they are fantastic engines well lived Aaron's the world for the strength and tuneability. So it's rude not to :-)

One imp is enough :-) I've still got to re-power my viva wagon! Plus I will enjoy playing Aaron's with just the one imp and improving it over time.
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Re: 1965 Datsun engined Imp. First drive!!!!

Post by yoeddynz » Sun May 19, 2019 7:24 pm

bazzateer wrote:Great stuff!

Not as fast as the camera operator's car though (they always end up ahead of you :wink: )
I'll have to tie a rope into the camera car...
[https://oldschool.co.nz/index.php?/topic/28896-was-yoeddynzs-1968-viva-mazda-v6-new-owner-welcome-guzzi-rat/
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Re: 1965 Datsun engined Imp. First drive!!!!

Post by yoeddynz » Sun May 19, 2019 7:26 pm

Thanks also to andy and Roy for the kind words. It's been fun!! Still more things to do :D Imp001
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Re: 1965 Datsun engined Imp. First drive!!!!

Post by johnh875 » Mon May 20, 2019 1:11 am

Congrats on the successful drive! Looks excellent, and great to see the nitty-gritty details of the tweaks you've done too.

Itching to get into things in my new garage, only a few weeks to go now.
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Re: 1965 Datsun engined Imp. First drive!!!!

Post by bks974c » Mon May 20, 2019 7:50 am

Congrats on finishing it, looking forward to the IMProvements as you go.

Time now to enjoy it.

Well done.

Scott
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Re: 1965 Datsun engined Imp. First drive!!!!

Post by Lotus-e-Clan » Mon May 20, 2019 10:41 am

Good to see a transplanted Imp in usable condition - so many don't get finished as Scott implied. :)

If you intend to use it in all weathers (may be not?), then I would consider installing under body panels to stop road filth messing-up that good-looking engine bay.

With your 1st class fabrication skills you should find it relatively easy to design and fit a flat floor to the engine bay without compromising cooling. It should improve aerodynamics too.

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Re: 1965 Datsun engined Imp. First drive!!!!

Post by bks974c » Mon May 20, 2019 3:47 pm

Actually I was IMPlying that a good project is never truly finished always an IMProvement here and there to be done :)

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Re: 1965 Datsun engined Imp. First drive!!!!

Post by tiker » Mon May 20, 2019 5:50 pm

Cracking little car beautifully engineered,
It a credit you enjoy driving it now after all the hard work
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Re: 1965 Datsun engined Imp. First drive!!!!

Post by Lotus-e-Clan » Mon May 20, 2019 6:18 pm

bks974c wrote:Actually I was IMPlying that a good project is never truly finished always an IMProvement here and there to be done :)

Scott
Apologies Scott I misinterpreted your comment. :oops: What I wrote betrays my thinking along those lines, rather than yours! :lol:

But yes ..always room for IMProvement - hence my weather-proofing suggestion. :)
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Re: 1965 Datsun engined Imp. First drive!!!!

Post by bks974c » Mon May 20, 2019 6:40 pm

No worries Peter.

Scott
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Re: 1965 Datsun engined Imp. First drive!!!!

Post by yoeddynz » Mon May 20, 2019 7:38 pm

Cheers fellas. I do know exactly what you mean Peter. Often is the case that once the hard work is done and a project is near completion all those little boring jobs that add up to finish it can kill off the mojo. I've followed many projects on the likes of retrorides or oldschool where the person gives up and the updates stop coming.
A project can certainly drag on.

This is still on going and will never be truely finished, as Scott was implying :-) so many finishing touches, so many upgrades planned, more modifications.

I like the idea of an under tray and will look into it. Even a half tasty that extends back to just behind the engine cross member would probably suffice at stopping the vacuum. It would then become a true super car with fully designed ground force aero..... :-)

A subtle front lip spoiler is on the cards for sure.. Just on looks alone.

Hannah got to drive it yesteryear evening. She loves it! I knew she would. Hannahs first classic was a little imp super she bought in the UK and she joined the imp club back then. Did a few local meets in Oxford. This was her first drive of one since then.

We went down to the coast, about 3km down the road from our property. First photo is from our neighbours place around the corner from us.

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Its going well but for the stumbly idle. Update on that soon.
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Re: 1965 Datsun engined Imp. First drive!!!!

Post by yoeddynz » Mon May 20, 2019 9:06 pm

So this stumbling idle. I cant quite tune it out because the throttle spindle was so worn. So last night I took the carb off and stripped off the linkages...

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The gap is quite large! ....

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I'll keep a look out for a better carb body but for now I have to improve this one. So I went through my collection of rubber washers and found one to suit, which I did. Its a good snug fit over the shaft and sandwiches in neatly between the body and the first bit of linkage...

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Then the other end. Nothing to sit a washer on. So I dabbed a bit of automotive silicone on top and let it set. It flexes enough to let the shaft turn so its now well sealed...

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I have yet to try it out. The car is booked in for a wof (MOT) today so wish me luck :)
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Re: 1965 Datsun engined Imp. First drive!!!!

Post by yoeddynz » Tue May 21, 2019 8:46 am

The little IMP is now all road legal !!!! :)

I refitted the carb this morning, hoping for the best but it was still terrible. I just couldnt get it to idle below about 1500 rpm and it had a big flat spot on light acceleration. So I gave up and we drove it to town, the long way through Kaiteriteri so I could have some fun on the windy road there. Wow its fun! Soooo much fun. Even with an engine that wouldnt pull properly, horrible flat spots, tyres that are definitely too high in pressure, a few clanks from the yet to be fully secured pipework, noise from the un-insulated engine bay shelf, noise from no carpets, fumes being drawn in through the old heater hose routing holes etc etc... it was still fun. It really is like a big go cart. The steering is lovely. Gear shift is great. Brakes getting better as they bed in. The temp gauge sat pretty much bang on an indicated 80 degrees C whch I reckon is more about 90. Fan only came on when we stopped, as expected so I was really happy about that.

We got to town and straight into the booked WOF slot. Our local friendly wof man just loved it. Kept saying how cute it was, how neat the install was etc. Really impressed. Did all the check things as usual, test drive and it was all good. We looked about all the neat stuff in his workshop....

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WOF attained and we went to the local council and got a years license. $47 - yay for old cars.

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Did a shop at supermarket, did the proper look back over my shoulder at my little Imp, sitting there in a sea of bland grey modern cars, looking sooooo tiny.

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On the way home we popped in to show it to another couple of fellas who run a nice country workshop and had sorted out the tyres for me. They too loved it and the older fella reckoned it was running way too lean and certainly had a big air leak somewhere. Then off home, this time driving over the much steeper longer climb. No worries even with terrible carb. No increase in temp. Yay for that.

I got home and removed the carb. Discovered two things. Firstly. Spot the schoolboy error here...

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Yep- That accelerator pump can go downwards for sure, but not if the lever pushing it down cant go up at the other end! My air filter base was stopping it. This also meant that along with only a tiny bit of travel I was also not getting the secondaries to open properly. Easily sorted with a hole, some alloy and some epoxy.

Second thing- this...

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There goes my air leak. Air getting pulled in through that huge split, past the accelerator pump piston and into the venturi. Well at least I am pretty damn sure that this is the culprit!

Reporting back with findings soon.....
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Re: 1965 Datsun engined Imp. First drive!!!!

Post by johnh875 » Tue May 21, 2019 8:41 pm

I always describe the Imp as a go kart for the road! The memorabilia in that workshop is pretty impressive too.

Glad you are finding the niggles.
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Re: 1965 Datsun engined Imp. First drive!!!!

Post by yoeddynz » Tue May 21, 2019 9:26 pm

Cheers John. Yeah its all little things now. The big job is over. I'm really relieved that so far it seems that the main modified things like brakes, cooling, clutch etc are all good. Really happy the cooling system is working well.

It certainly needs a bilge blower fan installed in the vent duct. There is heat there at the matrix but it needs to be pulled off better. Only above say 50km do you get any ram effect.

Going to strip carb down later and give it a good look over.
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Re: 1965 Datsun engined Imp. First drive!!!!

Post by yoeddynz » Fri Jun 07, 2019 10:41 am

Because I'm such a hardcore Friday night raver I'm here doing an update on an old car whilst my cat sleeps in front of the fire. Rock on.

This little Imp...its great fun!!!! :) I have not really clocked up many miles yet, as you'll find out why soon, but those miles that have been driven have been fun. Its taken a little while to get used to the balance, steering feel, brakes and sheer grip that exists. Still not fully confident at flinging it about but getting there. Its a giggle. I'm just weary of the slippery wet corners that are about now we are into winter here.
The little Datsun engine is a gem! Its still not quite perfect at idle and just off idle but once rolling its great. I can really see why the Datsun 1200 cars have such a following- they are about the same weight as an Imp with similar gearing and were well known for being peppy little performers. The engine sounds pretty cool when trashed. I have since found out that this is indeed a completely stock unit and it was a different engine that the previous owner, Rob, had fitted with a supercharger.

Anyway- onto fettling. There are always a few things to sort on a fresh build. First off was to sort out the dodgy running carb. In my previous update I thought I had found the problem with the accelerator pump boot being split. Turns out that wasn't the problem...

I managed to locate a couple of A12 carbs from a local fella for beer money. One was a complete standard 1200 carb with stock sized jets etc. I took my fitted carb apart and soon discovered that not only were all the jets completely wrong, way too big and pretty butchered as well they were also housed in the wrong carb for my engine! The carb I had fitted was off an A15 which has larger throats and venturis. Great for a slightly hotted up motor but not what I'm after right now. The leaning out issue was because someone had fitted a air bleed that was way too big for the primary jet, among the many wrong other jets.

So I rummaged through both carbs, got the best bits from both and assembled a nice new carb that was stock and set to factory specs. I had a page covered in jet numbers and felt happy in the knowledge that I can now possibly join the elite group of carb Barries forever chasing the perfect tune (when the know full well that injection is just soooooooo much better in every way! )

A photo of some carbs in pieces....

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So with the Imp now fitted with the right carb I took it for a spin. Because the work shop is now clogged up with the start of a tiny house build I had to drive it out from the back of the workshop and up the grass drive to the cabin. I thought it best to get some photos of it next to the other Imps...

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I did a few test drives and I had to remove the carb a few times to dial in the float height, getting pretty quick at that process I must say. The difference is huge. Much better all round except for a hesitancy just off throttle. I'll continue to tweak things and see if I can improve it but I am starting to wonder if the vacuum unit I got from another car for my electronic dizzy has too stiff a spring. I think it might not be advancing the ignition enough under light throttle loads as it should. Ill get back on that.

Next issue was a funny one. Not funny for the amount of pissing about I had to do to fix it but funny in what I found. A work of art really. Rob has to be proud of his handy work at creating such a masterful bit of Barry engineering! The story goes like this..

After getting back from a quick drive checking the carb was OK I noticed a horrible vibration in the engine. I popped the lid to discover a very out of balance main pulley. bother. I knew it was a hybrid pulley made up of what I think is Toyota pulley on the Datsun hub but I had never looked further into it because it just worked. But not any more. I removed the pulley to discover this on the back...

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Hmmmmm. Lovely welding. Purposeful. I'll have to grind that lot off and make a new hub. I'll start by removing those two screws....

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Eh?!!! its not weld. Its magic fake weld thats been machined into a flange(like)thing. Its wonderful! Just look at this art :) ...

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The Datsun hub had a crack running through down the keyway too. I had no choice but make a new hub to suit. First off I cleaned up the pulley and had its running perfectly true...

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Then I popped to my local steel supplier and get a big lump of steel bar from which I machined a new hub, with a centre locator to tightly locate pulley central. In photos..

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Then the internal keyway. When I was working as a (young) fitter turner back in the 90s I would use either a broaching machine or a shaper, depending on the size of the key way. I have none of those tools. I did contemplate milling it from each side with a end mill and filing it out square but that would take ages on this fairly hard 1040 steel. So I made my own internal shaper bar to use in the lathe and just scraped out the keyway using the carrige. I bought a lump of 20mm bar at the same time as I got the round and cobbled together a tool holder from it. This will now be handy for future jobs I'm sure...

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and in action (well about as actioney as a photo of a non moving lathe tool can be...)

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Resulting in a nice neat keyway..

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Which fits nicely right here. Beefier then the original Datsun offering too :)

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Hub drilled and next to pulley..

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And altogether now, in a uniform coat of black paint...

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Much better. In order to tighten the main bolt, of which I had to buy a new slightly longer one to allow for the beefier hub, I had to make a tool to hold the pulley. I had tried tightening it up with the car in gear, on the ground, with the handbrake on but I didnt like the feel of trying to put the 110 lbft through the transmission like that. so yeah- tool time. Now I have another random tool to got in my wooden box of other random tools specific to only one thing...


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Doing its random tool thing...

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So I had a working Imp again that was not going to rattle apart. Best thing I do is to take it for a drive. I took it to town where we met Sam and is son Chris, who jumped at the chance to go for a ride with his Dad in the little blue car. Here they are returning...

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While in the shop buying stuff a Honda city turned up and parked (badly) next to the Imp. What I always think of as tiny cars looked huge next to the Imp...

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We went to the steel merchant for some more steel bits for another project. The rear opening window is handy for shopping. Note the lovely old land cruiser...

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While in town I rang Rob, the previous owner of the original race car shell that donated all the running gear for this restoration. He popped down and met us and had a good look over it. I reminded him of how I'd love the Weber sidedraft manifolds he had left over from his ownership. Well good old Rob actually popped home afterwards, found them in his piles of stuff, tracked us down later on in town and handed over these to me ! :) ...

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Wow! awesome. Top bloke. I'll now be able to fabricate a decent inlet setup for injection in the future. Yes!!!!

Later on that afternoon we parked next to another small car...

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This evening Hannah and I took the Imp out for a hoon on our local roads which are just perfectly made for little nippy cars. It was such fun! I love it when the (tiny) little secondary opens up. Its got a lovely induction sound (right behind our ears, even with two thick blankets covering the engine cover..)

We went for a nice evening walk and I took a photo of it parked up on the near the beach...

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Closer...

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Tune in next time to hear about the stupid mistake I made when buiding a cold airbox setup....
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Re: Datsun engined Imp. Hub of the problem, keyway to succes

Post by 617sqn » Fri Jun 07, 2019 11:00 am

Fab stuff Eddy ! 8) you're a well tooled up clever geezer, that's for sure.

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Re: Datsun engined Imp. Hub of the problem, keyway to succes

Post by Dave ' Linwood ' Lane » Fri Jun 07, 2019 11:50 am

Top job as always :)
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Re: Datsun engined Imp. Hub of the problem, keyway to succes

Post by Lotus-e-Clan » Fri Jun 07, 2019 12:28 pm

Fabulous work on that pulley! :o

Your Imp's stance is very cool as is the colour scheme. 8)

Driving rear engined cars will make you a better driver once you have found the limits ..just make sure to do it on a big open car park rather than on a country road with ditches like I did as a stupid 17 year old!

You can do fantastic handbrake turns on dry tarmac into 90 degree corners when you've mastered it. At least I used to be able to as a less-stupid 18 year old (about a year after ditching it)....45-ish years later I'm not so sure I'd catch-it right. And you will learn pretty quickly NOT to lift-off in corners (if you haven't already). Keep your foot-in and you can feather the throttle to manage the rear stability and front's tendency to understeer..even in the wet. Clan004
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Re: Datsun engined Imp. Hub of the problem, keyway to succes

Post by yoeddynz » Fri Jun 07, 2019 9:24 pm

Cheers!!! That's some good info there. Driving this Imp is quite different to my previous faster car, the Viva HB with 220 bhp. The Viva was pretty well sorted but had much heavier steering. It would certainly kick out on either too much throttle on or after the apex or could let go if you lifted off too much. Typical of a lightweight powerful RWD car without the aid of modern IRS rear end. It was always much easier to handle when a road was smooth. But reality is that, like the absurd condition of the roads in Blighty, many roads here can be lumpy in the corners.

If the Viva stepped out it was easy to catch. Much much easier to catch then the supercharged aw11 Mr2 I owned when I was young. That thing taught me all about spinning out!!!! Very sketchy cars the 1st gen Mr2. Once they let go you have to be very quick to catch it and then not over correct!

The Imp so far has just stuck. No feeling of the rear end coming round at all. Not yet.... :-) I am more concerned with a potential lack of grip in the front and am very weary of it ploughing straight on in a slippery corner. So I must say I am being quite careful and choosing where I open it up. If I know that a corner I'm approaching is a slippery one I will brake and get my entry speed right down before it. No place to be a rally hero eh! Its winter here and some corners around our valley will have ice all day long if its a cold one.

An example of how serious a silly off could be happened last week. About 2km up the road from our driveway , on the Riwaka hill, a Toyota pickup went straight off a cliff on a tight bend. Driving too fast and they ran out of talent. Hannah spotted the pickup later that day. Its bl***y amazing that the occupants both survived! Their dog died in the crash though (no seat belt for doggy)

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Two weeks prior to that a mate had a whoopsy a few corners down...

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He survived but his Honda didnt.

Last year a fella went off on the same corner as the ute above. He later died in hospital.

We have many big hills around here with fantastic corners ideal for Imps. But the results of any off can be quite dire. So I'll play it safe and build up my Imp driving skills carefully :-)
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Re: Datsun engined Imp. Hub of the problem, keyway to succes

Post by Lotus-e-Clan » Fri Jun 07, 2019 10:20 pm

Flippin heck. Dangerous country out there! Those utes have far too much power for their chassis maybe!

The front end is sensitive to wheel camber. If you have too much negative camber it will understeer in the wet at normal low speeds on roundabouts (normal road tyres up to 175 width at the correct pressure).

I found that no more than 1/2 a degree negative on the front is good. The camber measurement is made laden. Unladen (depending on springs rate fitted), you might see a tad of positive to get 0 to 1/2 a degree negative laden (need to experiment). Too much negative and there is less tread gripping the road on initial turn in and it will plough-on in the wet at low speed (very little body roll at low speed to increase grip).

My clan is currently still on 135/80/13 front winter tyres (stretched side walls on to 5.5J rims) and turn in great with near 1/2 a deg of camber. Rears are unstretched 175. You don't need a lot of width on the front (of a Clan) for road use. 135 digs in nicely. I will be swapping to sticky 175/55 13 fronts (Avon CR500 semi-slick Caterham tyres) soon as the summer properly starts up here (205/50/13 rear). The CR500s are great wet or dry as long as the temps are not too cool. The car has less acceleration on the wider rubber and more drag at high speed...so there is a cost with the wider sticky rubber unfortunately. Clan004
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Re: Datsun engined Imp. Hub of the problem, keyway to succes

Post by yoeddynz » Sat Jun 08, 2019 7:54 am

yeah i'd like about that much camber. no more. I'll measure it again and I can set happily raise the frnt end ever so slightly to bring it back. I wanted to drive it a bit and let things settle. I have spacers between my lower mounts and the spring platforms so I only need to make slightly longer items to suit.

This has 175/60 tyres on it. Certainly not a flash brand but they seem nice and soft. I was not sure on what pressure to run them at so I have gone for 30 on the back and 23 on the front. It certainly rides and grips much better then when it had 28 on the front (what they came pumped up to me after fitting).

Id love to know what pressures, with the relevant tyre sizes, others on here are running?

I'm also going to corner weight it. I tried with our scales but until I lowered it down on a back wheel I was not sure how much the scales would go up to. They tapped out at 130kg. I'll try again with a pair of scales otherwise i'll look to using a friends proper race car corner weights.
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Re: Datsun engined Imp. Hub of the problem, keyway to succes

Post by bazzateer » Sat Jun 08, 2019 8:00 am

yoeddynz wrote:I am more concerned with a potential lack of grip in the front and am very weary of it ploughing straight on in a slippery corner.
What tyre sizes and pressures are you running front and rear?
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Re: Datsun engined Imp. Hub of the problem, keyway to succes

Post by Lotus-e-Clan » Sat Jun 08, 2019 8:26 am

23 psi is a tad high for fronts - especially as 175 is wider than std Imp fronts.

I run 18 psi on the skinny front winter tyres and 16 psi on the 175 CR500 fronts.

18 psi is a std Imp number. and 16 psi is a standard Clan number for fronts.
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The fat summer rears would bounce the car off the road at 30 psi so 24 is the 'dialed-in' number for these. Depending on sidewall construction and profile, wider tyres as a rule of thumb grip and handle better with less pressure.

BTW. I don't run a front rad. Those that do might want slightly higher pressure in the fronts.
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Re: Datsun engined Imp. Hub of the problem, keyway to succes

Post by yoeddynz » Sat Jun 08, 2019 10:34 am

Are the Clan's lighter then the imps by a large amount?

I'll try out softer all round for sure. I prefer cars with a bit of suppleness to the tyres. But wow.. 18 seems so low.
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Re: Datsun engined Imp. Hub of the problem, keyway to succes

Post by yoeddynz » Sat Jun 08, 2019 10:36 am

bazzateer wrote:
yoeddynz wrote:I am more concerned with a potential lack of grip in the front and am very weary of it ploughing straight on in a slippery corner.
What tyre sizes and pressures are you running front and rear?


This has 175/60 tyres on it. Certainly not a flash brand but they seem nice and soft. I was not sure on what pressure to run them at so I have gone for 30 on the back and 23 on the front. It certainly rides and grips much better then when it had 28 on the front (what they came pumped up to me after fitting).
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Re: Datsun engined Imp. Hub of the problem, keyway to succes

Post by The Nun » Sat Jun 08, 2019 10:43 am

I used to have very soft and sticky Yokohonos on mine, superb grip but they were always covered in chippings they picked up that then came out and chipped the paintwork :?
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Re: Datsun engined Imp. Hub of the problem, keyway to succes

Post by Lotus-e-Clan » Sat Jun 08, 2019 11:17 am

Clan is definitely lighter than the Imp by about 100 -150 Kg but std REAR pressures for a std Clan are the same as std Imp ie 30psi on 155/80/12 road tyres.

Imp std front is 18 psi on 155/80/12

Clan std front is 16 psi on same tyres - this accounts for the lighter Clan front in particular.


However the lightness differential between the Clan and the Imp is more significant in the dramatically different spring and damper ratings. This is a major contributor to the Clan's superior grip handling and ride.

Clan 68 lbin front spring - Imp something like 195 lbin front.

Clan 260 lbin rear springs - Imp something like 410 lbin rear

Clan damper ratings are bespoke to the Clan.

The std Clan rolls a lot on the softer springs and so the weight transfer into the corners is greater (relatively) than the Imp . The roll/weight transfer adds to the grip when turning-in. Lotus engineers selected the spring damper rates for the Clan. Lotus have a long tradition for preferencing well-damped soft springing with a long travel.
This suspension design philosophy is well proven - but unfortunately the roll on the Clan LOOKS AWFUL in mid-corner - not quite as bad as a Citroen 2CV -but almost! :lol:

That's one reason (dreadful roll) many Clan owners uprate the spring rates (me included). It's the wrong thing to do mind - I do regret the stiffer springing on mine from time to time. The Clan turn-in was much better on the softer fronts and the ride was definitely better. The Lotus engineers knew their stuff. Clan004
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Re: Datsun engined Imp. Hub of the problem, keyway to succes

Post by bazzateer » Sat Jun 08, 2019 12:30 pm

yoeddynz wrote:
bazzateer wrote:
yoeddynz wrote:I am more concerned with a potential lack of grip in the front and am very weary of it ploughing straight on in a slippery corner.
What tyre sizes and pressures are you running front and rear?


This has 175/60 tyres on it. Certainly not a flash brand but they seem nice and soft. I was not sure on what pressure to run them at so I have gone for 30 on the back and 23 on the front. It certainly rides and grips much better then when it had 28 on the front (what they came pumped up to me after fitting).
I'd start at 18 front and 28 rear and see how you go.
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Re: Datsun engined Imp. Hub of the problem, keyway to succes

Post by yoeddynz » Sun Jun 09, 2019 1:26 am

I'll try that out and report back :-)
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Re: Datsun engined Imp. Hub of the problem, keyway to succes

Post by yoeddynz » Mon Jun 24, 2019 9:31 am

Baz- I have dropped them to 20 at the front. Heaps better. Might go lower and see if its even nicer. Turn in is still good but certainly slightly heavier steering. However much quieter on the road!

Well now.. its been a few weeks and time for an update. So far the Imp has been reliable and not let us down but it has also been true to its English form and left a few little puddles about. I'll talk about them soon.

We took it on its first big road trip which was fun, although a bit noisy. I couldn't really cane it super fast on the hills because Kevin the cat had to come on the trip with us. It was a few days away to visit my parents so we cant just leave the kid at home...

The car did the trip with no hassles and returned an OK 35mpg, not bad considering its geared quite low, has had heaps of sitting on the spot being tuned and due to the constant annoying flat spot right off idle I had to accelerate faster then I'd normally bother in average driving. It certainly hoons along very very well although it has an exhaust boom right around 60mph, which is around 4000rpm thereabouts. It became a bit too tiresome however should be better now I have added a load of sound insulation on the back parcel shelf.

So anyway.. the wee Imp ran well and got us to Blenheim and back. But before that big trip I wanted to sort a few things. One job was to build a cold air fed filter box and carb lid to let the engine suck on some cooler air rather then the super hot air floating about in the top of the engine bay, due to Imps not having the luxury of lots of cold air running through over the engine.
So I built a filter box, sized to take a modern Honda filter. I have made the box large enough to handle bigger pipes and the volume that might be needed when I plan to upgrade the induction. Box...

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With filter in place...

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This box fitted under the parcel shelf above the gearbox. Sort of out of the way and hidden but easy enough to get to. It was fed with a flexy alloy pipe from under the car. Another section of pipe headed backwards to a plenum/tophat thinggee I made for the carb...

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It was all going so well I thought. I splashed some black paint on it all so it looked a bit neater...

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Then I fitted the tophat to the carb. This is where things went a bit... tight. It seems that I had completely forgotten to measure how much room I had just above in front of the carb. Not enough it turns out :( ....

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The engine lid wasn't able to go back in place! A few choice words that somewhat rymmed with duck and hit along with a sentence that sounded quite similar to 'well you stupid punt' were uttered.

I then calmed down, realised that at least I have now got a filter box sorted for future upgrades and with that I removed the lot and refitted the previous air filter I made.

At least its winter so a bit of hot air cant hurt :-)

I did another couple of jobs before the trip. I swapped out the fuel gauge which wasn't reading correctly for a spare unit I had..

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I was also fed up with trying to adjust the clutch. The slave cylinder fitted had a 7/8" (22mm) bore and being pushed by the standard Imp 5/8" (16mm) master cylinder, which happens to be the same size as what the Datsuns use. However- Datsuns use a smaller 17mm slave to get the correct amount of stroke at the slave. I wasn't getting enough stroke so the clutch pedal and release fork clearences had to be set very tight to clear the gears. But I did have a very light pedal...

So I worked out that the amount of stroke available from the Imp pedal, whilst being very close to that on a Datsun, was not quite enough I could get a good working system with a slave of around 3/4" (19mm). However- there didnt seem to be any slaves available out there that had the same mounting lugs, in 3/4" bore, with a metric fine hose thread.

But I did have some spare random 3/4" seals, some stainless bar for a new piston and a big lump of alloy. So I made a new slave cylinder to suit. I could have sleeved the existing one down and I have a 3/4" reamer to help but I wanted to keep that one intact in case it all went pear shaped. Plus...its more fun making things ! :)

I offset machined the lump of alloy down in the 4 jaw, bored and reamed it to suit, milled the shape up and machined a new piston to suit. But I was having too much fun and forgot to take many photos..


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New next to old...

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It works heaps better! I can now have a bit of slack at the pedal and at the release bearing and still get my gears.

Another job was to take the carb apart for the 14th time. I'm getting very quick at this and can field strip a Hitachi 306 carb in under 15 seconds, blindfolded, with both hands tied behind my back, whilst under water breathing through a straw.

The carb had a few leaks. I realised that the top lid was pulled out of shape...

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I carefully filed it and the body flat, cleaned it out again for the 10th time and made a new thicker gasket to suit...

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On the next test drive the leaks had gone but I had still had not cured the flat spot. So I gave up and made a parcel shelf instead. I did have an original Imp one but it was a bit wobbly and a pain to fit. I made a new wooden one for the passenger side so now actually had somewhere to sit our phones, wallets, bag of Werthers originals, old parking tickets, a broken pen, out of date fuel vouchers and, most importantly, a screwdriver for constantly tweaking the carb settings.

Again, so much fun but no photos. I finished the shelf the morning we set to leave. We plonked Kevin the cat into the car and set off. A lovely trip was had with the only downer being that the cold I had caught at fire brigade practice a few days before was really kicking in to full runny nose time, while the weather was a bit... Wintery. Got to test the wipers out though (must fit intermittant control kit I have)

On the way over to Blenheim. You can spot Kevin.

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I took my Dad out for a hoon in the car. He loved it and only complained about the wipers being in the way of his view. Not a car fault but more down to the fact he must only be about 4'5" tall now...


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Back home and more recently things have happened. I weighed the car at the local tip...


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750kg. The guy said the scales are within 10kg. So its in the ballpark for what I was guessing. A bit heavier then a standard Imp to be expected with a heavier engine, seats, exhaust, radiator and associated cowling, water pipes etc. But still light enough :) I think standard Imps are around 700KG ?

More recently- one of the output shafts on the box leaks. I think it might be the shaft moving out just a touch too much on certain corners and the seal running off the land its meant to seal on. I might have to preload the output shafts. I had set the spacers for the bmw couplings to have pretty much no preload when the car is sitting flat with the full weight on the wheels. Do I need more preload to allow for outwards movement of the axle and if so then how much?

Or the seal land on the shaft is too worn. Or the new seal I had fitted has moved. The car will soon go on the hoist and I'll have a look. Cant really drive it until I sort this. Expensive stuff this oil- even more expensive if its loss means a bother transmission.

In other news I have made a parcel shelf for the drivers side. Now I can stash all my own crap within easy reach ..

I am going to make some speaker boxes to mount under the shelves alongside a headunit. At a later date when I can afford to do so I'll fit an Amp and sub. I do like my music and there is only so much of Datsun A12 at 4000 RPM booming I can cope with so I need to drown it out.

That is about all for now. Wish me luck with my seals...
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Re: Datsun engined Imp. First roadtrip...

Post by The Nun » Mon Jun 24, 2019 10:47 am

You don't want the drive spiders moving axially in the gearbox at all, I know when folk fit solid drive shafts they need a spring on the sliding spline section to keep the spiders pushed into place in the gearbox, Robin Human has just started offering a solid drive shaft conversion kit for the IMP, and his has the necessary axial springs. Whether he might be kind enough to tell you the Spring strength he uses he may do, no harm in asking then you can do a similar thing, or increase the spacer thickness you have accordingly?
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Re: Datsun engined Imp. First roadtrip...

Post by yoeddynz » Mon Jun 24, 2019 7:23 pm

Cool. Cheers. It's only that one side that has leaked and coindently it also happens to be the side that has slightly thinner spacers by a couple of mm. I had just machined the spacer width to suit the gap. Later on I started noting that whenever I saw a photo of a standard imp setup the rotoflex couplings had quite a bit of flex pre-loaded inwards to obviously allow for the driveshaft to move out as the wheel goes up through its travel. (is this one reason rotoflex couplings can be a bother to fit for newbies?)

Has anyone ever measured the amount of axial movement on the axle?

I'll ask Robin. Is he on here or is it via Facebook I'll get him?
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Re: Datsun engined Imp. First roadtrip...

Post by The Nun » Mon Jun 24, 2019 8:06 pm

He's on here as "tzarrobin" so you can pm him, he's on FB too.
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Re: Datsun engined Imp. First roadtrip...

Post by yoeddynz » Mon Jun 24, 2019 9:23 pm

Ahhhh yes- I remember commenting about some driveshafts on a post a few days ago about the new driveshafts on Bryan Fletchers Tikimobile. They'll be the ones you talk of. They look good...

Image

The thing I had commented on, which as yet has seen no reply, was that with solid driveshafts like that on an Imp you would surely have to run a clutch disc with a sprung centre? Otherwise there would be nothing to take out transmission shock.

I'd get away with it on my Imp because it has a standard Datsun clutch with a sprung centre.

Anyway- I'll contact Robin.
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Re: Datsun engined Imp. First roadtrip...

Post by The Nun » Tue Jun 25, 2019 5:22 am

I think some use a sprung clutch centre plate like the Morris Minor uses, but they have problems of their own with rattling springs and the springs can even fall out in some cases.
Depends how you drive to a certain extent too, I remember watching the Greetham Imps at Donnington back in the 80s and noticed they always got the car rolling before they put their toe down, what breaks Imps is red lining it and then dropping the clutch, that's more abuse than anything.
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Re: Datsun engined Imp. First roadtrip...

Post by 617sqn » Tue Jun 25, 2019 7:25 am

And what about noise transfer ?

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Re: Datsun engined Imp. First roadtrip...

Post by yoeddynz » Tue Jun 25, 2019 7:33 am

Yeah I'm not one for abusing drivelines and dumping clutches. However I'd still always want something with a bit of give in the drivetrain, like Andy said if only to remove noise.
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Re: Datsun engined Imp. First roadtrip...

Post by The Nun » Tue Jun 25, 2019 8:10 am

617sqn wrote:And what about noise transfer ?

Andy G
Ive never tried a solid driveshaft conversion so dont know if they make the car seem like youre driving a tank, the write up in the metalastik catalogue does say fitted for smoothness and quietness, it doesnt mention about they wind up and split, the power unit and suspension arms are on rubbers for isolation anyway, but then if it makes it terrible what about the Elan conversion, youre removing 4 doughnuts there for what is basically the same idea, do they end up rough too? I cant imagine it as they would be lots of complaints written about the fact, all I can find is recommendations for doing the mod?
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Re: Datsun engined Imp. First roadtrip...

Post by 617sqn » Tue Jun 25, 2019 8:15 am

I said I was concerned, not convinced. And the Lotus would have different engine and gearbox mounts in order to alieviate any noise transfer. The gearbox isn't an Imp item either. If worn UJ's can induce noise......

And the cost ? Is it actually worth it ? Not from my perspective it isn't.

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