[trt74]

As a new member to this forum and a novice to car mechanics I would very much like to pump the collective expertise in the forum for ideas about the following problem:
Recently the gearbox and J-ype overdrive of my TR6 have been overhauled because of serious leaking and synchromesh problems. This work was done by a Tr-register recognised workshop. After the full overhaul there were no problems at first. But after about 500 miles shifting up from 2nd to 3rd gear and down from 4th into 3rd became inreasingly difficult because of clashing of the gears. Shifting without clashing in these gears is now only possible by double clutching. The other gears cause no problems.
As all synchromesh rings etc. have been replaced I can't imagine wear being the cause.
Does anyone have any suggestions to the cause and solution of this problem?
Thanks,
Tim

[foster461]

I wonder if the problem is not with the gearbox but with the clutch ?. Maybe it is not fully disengaging for some reason. When the car is stationary do you have any difficultly/grinding getting it into first or reverse ?. Causes could be poor hydraulics, incorrect installation of slave cyl and push rod or the dreaded sheared pin allowing the fork to rotate.

Stan

[trt74]

Thanks Stan, but one would think the problem would be in all gears, not just the 3rd, if the clutch would be the cause or is this too simplistic?

[marvmul]

If the clutch would be the cause, and the synchromesh is good, changing gears would be difficult (especially in reverse and lower gears), but there would be no crushing noises, no clashing of gears. It seems that a fault is occuring on the main shaft, perhaps the whole lot of gears and synchro hubs is moving on the main shaft when you change gear, because of failing circlip (i.e.the one that is difficult to remove and that can only be used once). The 2nd gear bush, with the rim, is a known weak one, but I think it won't fail after such a low mileage.

[jonlar]

Tim, welcome to the forum!   Sounds like duff synchro. rings to me as well.   Take it back to them that did the work (hope it's still in warranty timewise).

[simon iregbu]

Quote

If the clutch would be the cause, and the synchromesh is good, changing gears would be difficult (especially in reverse and lower gears), but there would be no crushing noises, no clashing of gears. It seems that a fault is occuring on the main shaft, perhaps the whole lot of gears and synchro hubs is moving on the main shaft when you change gear, because of failing circlip (i.e.the one that is difficult to remove and that can only be used once). The 2nd gear bush, with the rim, is a known weak one, but I think it won't fail after such a low mileage.

My friend's car seems to be exibiting a similar problem to that described. After driving the car for a while and coming to a stop, it can be virtually inpossible to get the car to go into any gear. There is no crunching of gears, it just will not go in. With a bit of effort you can force it into 2nd or 3rd and then it seem to be okay again.

When the engine if off the gears can be selected relatively easily but once the car is started the amount of effort required increases. When selecting revers gear there is a crunch of the gears before engaging which would indicate that the gearbox is not fully dis-engaged when depressing the clutch. I have replaced all the seals in the master cylinder as they had started to deteriate and checked the seals in the slave cylinder (and these were okay). The amount of slave cylinder piston travel is just under 1/2" whic indicate a bit of wear but I would have thought not so much that would cause this problem.

I have also checked the end play on the crank (missing thrust washer) and there appears to be very little. The gearbox was removed to check that the fork pin was not broken and I took this to a 'gearbox specialist' who at 2 hours notice on a Sunday performed a visual check and indicated that the gearbox seemed okay.

I also took the top cover off the gearbox and turned the engine over (with and without the clutch depressed) to see if the mainshaft would dis-engage. And it did not, I am thinking that the clutch maybe the problem.

Dose anyone else have any other ideas?

Thanks

[Richard Crawley]

Tim
I go along with the consensus & agree there seems to be a problem with the rebuilt box & the synchro rings in particular; go back to the supplier ASAP.

[GSKTR4]

Richard CRawley, on July 21 2005,23:52, said:

Tim
I go along with the consensus & agree there seems to be a problem with the rebuilt box & the synchro rings in particular; go back to the supplier ASAP.

Agreed, I've just had exactly the same problems on my TR4 (v similar box) - newly rebuilt gearbox with all new/uprated parts, started crunching from 2nd to 3rd within 100 miles (on ordinary roads at normal speeds) - stripped the 'box down to find the brand new synchro rings had worn so much that the inner surfaces were almost completely smooth, rendering them useless - I have a feeling they were never quite the right size from the start.

I managed to locate some proper OE parts and it's been absolutely perfect ever since.

Mine were from Revington but they are denying all responsibility - maybe I should push it further now as I was told they had sold lots of sets and I was the only one to report a problem - clearly that's not the case as I expect all the suppliers get their synchro rings from the same manufacturer these days.

Good luck - if you need any help just shout.

cheers

Andy

[AndyTR250]

Simon: I had recently experienced a similar set of problems on my TR250. I found that when I used my toe to fully retract the clutch pedal after a gearchange that the problem went away. My return spring was missing. I also had noticed a slight improvement earlier after having removed the clutch MC cap. I concluded that the cap vent hole was blocked which was preventing the MC from returning to a fully "relaxed" position. With a cleared vent hole and new return spring the problems have not reoccurred (touch wood!). I also recently replaced the clutch pedal which had a greatly elongated hole where the clevis pin passes through, and replaced the pedal shaft bushings. Improving these removed a lot of slop out of the system, which also helps.
Cheers,
Andy

[simon iregbu]

Andy

Thanks for the advice, I will check out the return spring and the vent hole in the top of the m/c.

Simon

[trt74]

Thank you all very much for your opinions and advice. Much appreciated!
I took the car back to the shop that rebuild the gearbox in the first place ( which in my case meant from Holland back to England - but it was under garantee) and it iturned out to be the problem Andy described: after market synchromesh rings which had worn out completly within 100 miles!! Secondhand OE rings in good condition have now been fitted and the problem seems solved. I picked up the TR yesterday and very much enjoyed driving the country lanes this car was made for in beautiful wheather back to the ferry; shifting is now no longer a problem.

Tim