Jumping out of 3rd gear !!!

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apeximp
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Jumping out of 3rd gear !!!

Post by apeximp » Wed Jun 30, 2010 6:50 am

My gearbox is at high revs (6k plus) jumping out of 3rd gear !! its ok in 1st and 2nd and 4th but as i get it under load in 3rd and the revs get up it just bangs out on its own ?

The box has a lowered 3rd and 4th gear set and i think they are jack knight items , as far as i know its not a dog set up !

Box was rebuilt 4 years ago but has only just done 1000 miles

this problem was never noticed until i started to race the car as i never got to them kind of revs on the road !

Can anybody offer any advice please ? :x

Am losing so much time on the track with this fault there is no point of entering any more races till this is sorted out !.

Jim
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kilty
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Re: Jumping out of 3rd gear !!!

Post by kilty » Wed Jun 30, 2010 6:58 am

Probably needs new 3rd gear baulk ring. I`ve got a couple that jump out of 2nd, and that`s what they need.

Drew
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Re: Jumping out of 3rd gear !!!

Post by Impecunious » Wed Jun 30, 2010 9:45 am

Sorry Drew, It's not the baulk ring. The function of a baulk ring is to equalise the speed of rotation of the synchro hub and the output gear which you intend to select. The synchro hub sleeve then slides across the baulk ring engaging the small clutch teeth on the side of the driven gear. When you have a worn baulk ring, the speeds are not equal when gear engagement takes place and the clutch teeth grind against each other - a familiar noise to many Imp owners....

The problem will usually be a worn synchro fork unable to fully engage the hub, too much endfloat on the pinion shaft allowing component shunt (loose mainshaft nut as well as general wear) or worn clutch teeth unable to stay engaged under the spring ring and selector ball detents. If the box has been rebuilt without access to the Churchill special tools, there is no way of knowing which selective washers to use to position the components on the pinion shaft either. This may result in third gear being too far towards the fourth gear position for the synchro fork to fully engage the hub. There are other problems that contribute to jumping out but these are the usual suspects.

I am assuming it is a late type synchro box - the early synchros should be binned (unless you have an early car which you want to keep original) as they have no internal spring ring detents in the synchro hubs.

Dave W.
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Re: Jumping out of 3rd gear !!!

Post by kilty » Wed Jun 30, 2010 10:22 am

Don`t apologise, I`ve just been given the wrong information. :D
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Re: Jumping out of 3rd gear !!!

Post by apeximp » Wed Jun 30, 2010 11:19 am

hopefuly get the car back to ron aspinwall in the next few weeks and the gearbox out and off to you dave ?
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Re: Jumping out of 3rd gear !!!

Post by Impecunious » Wed Jun 30, 2010 4:58 pm

Anytime Apex, not far for you to travel either...
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Re: Jumping out of 3rd gear !!!

Post by Lotus-e-Clan » Thu Jul 01, 2010 9:03 am

BTW Dave

Your straight cut C/r box is running great and is now leak free. Thanks for fixing that.

It also sounds a lot quieter from inside the Clan now I've swapped the "solid" competition transaxle mounts for std items.

Just wish I had a fifth gear to change up to @ 80 mph. :lol:
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Re: Jumping out of 3rd gear !!!

Post by apeximp » Mon Jul 19, 2010 7:40 pm

well dropped of my gearbox with Dave last fri and today he came back to me with another very sorry tail :( Major internal damage to several diffrent internal parts of the gearbox ! Some showing major wear some just broken ! Again i am so disapointed with another so called serviced / re built / up graded major unit that has failed ( engine went bang after 110 miles ) after much work at much expense ! Not only in build costs but time off work transportation of the car to and from repair centers and remedial repairs due to car standing out side in the snow and rain while it should have been in doors being worked on ! sorry for the rant but after 5 years building the car and only two troubled races i could all most sell the whole lot up and give up because of the problems with some so called imp guru's ! Well lets hope after the current rebuild again at great cost (but i feel more reliable) hope to be up and running for the final race at silverstone in oct ? Jim :|
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Re: Jumping out of 3rd gear !!!

Post by Lotus-e-Clan » Mon Jul 19, 2010 8:46 pm

It's disappointing to hear about loss of trust. During the 70's and 80's I had no problems with any of the work I had done by engine shops (Andy Chesman mainly) but since coming back into Imp stuff I've been disappointed with other peoples work on more than one or two occasions.

I guess like me you don't mind honest mistakes (as long as they pay to rectify) but when you start to suspect you've been taken for a mug then the bad feelings that follow take a long time to die away. And it's bad for business too. I don't understand why people take a chance with their own reputation..... or maybe they are not knowingly taking the p and it's just case that after a long time doing things in a certain way their luck has just run out. :|
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Re: Jumping out of 3rd gear !!!

Post by Dave ' Linwood ' Lane » Mon Jul 19, 2010 9:06 pm

I rebuild my own engines , Although I dont race they do get used and abused a lot , If it goes bang its my fault , Ray Payne was the last person to build me an engine , sadly no longer with us
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Re: Jumping out of 3rd gear !!!

Post by apeximp » Mon Jul 19, 2010 9:23 pm

i cant and will not name names on here but he knows who he is ! And i think the main problems is that when work presents its self to him he just says yes and takes it on , then when the dead lines come or the customers start to get twitchy the engines and gear boxes are then quickley throwen together with a wing and a prayer ! . Wont be using this guy again burned my fingers twice there wont be a 3rd time and am now using guys who have been very highley recomended rather that this guy who all i know hear about is problems and complaints !
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Re: Jumping out of 3rd gear !!!

Post by Lotus-e-Clan » Mon Jul 19, 2010 9:24 pm

Yep agree with you Noddy, doing engines yourself (even a full race spec) is the best way and I've always done mine even way back in the 70's...Chesmans did the machining and clever bits though.......but i like the idea that transaxles are rebuilt with the proper Churchill tools and pre-loads and so the best choice is the guy with the right tools, right attitude and a sense of customer service.
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