Gearbox bolt

[M7662]

Hi moved my elan s4 out garage today and gearbox oil on floor jacked it up and the bottom bolt on rear of gearbox loose tried to tighten up but thread has gone anyone on ideas of repair

[alan.barker]

try a bolt a little longer there still might be thread deeper in hole.
Alan

[rgh0]

I presume you are talking about one of the lower bolts on the tail housing to the gearbox centre case.

It can be drill and a helicoil fitted if not enough remaining thread for a longer bolt but that would require the engine and gear box out and the tail housing to be removed to dril out and helicoil the centre case

cheers
Rohan

[2cams70]

Pictures always help in these situations. 100% of these types of issues are due to abuse and people not knowing what they are doing. Some numbnut could have tried to force a Metric thread bolt into an Imperial thread. It would take massive, massive over tightening to strip the thread if the correct bolt had been used. If you throw away an incorrect bolt and replace it with the correct type you may just avoid a disaster but only if you are really lucky. As has been alluded to also someone may have used a bolt that was too short in which case only the upper threads may be damaged so if you install a bolt of the correct length there may still be enough good thread left.

It really pains me sometimes hearing what some people do or try to do to old cars.

[promotor]

Hi moved my elan s4 out garage today and gearbox oil on floor jacked it up and the bottom bolt on rear of gearbox loose tried to tighten up but thread has gone anyone on ideas of repair

If it is stripped and all the material is gone then you can either repair with a Helicoil (a coiled wire insert that effectively replaces the missing threads) or a Time-Sert (which is a solid threaded repair "bushing" if you will) - Helicoil is cheaper to do, Time-Sert is a marginally better but a lot more expensive to do. Both methods (and probably any other that I haven't thought of) require the gearbox stripping completely as the jobs will produce metal swarf, which you don't want in your gearbox!

Be careful not to attempt to use a much longer bolt in the gearbox in this position as the threaded hole goes straight through to the cluster gear teeth - you risk damaging the gear teeth if you do.

[elated]

First step should be to check whether the thread of the fallen-out bolt is correct imperial.and of full diameter along its entire threaded length
Then use a probe to determine the total depth of the receiving hole and whether worthwhile thread remains and over what length.
The third step will reflect the information so gained!
Gordon

[joe7]

I had to do the same repair using a Helicoil . Worked great. Be sure to trim off the excess on the inside of the inside of the gear case.

[alan.barker]

The helicoil length should be trimed before fitting. Take care when you break the Tang off after Helicoil has been fitted. You don't want the broken Tang in amongst the Gears. The top of the Helicoil should be a 1/4 turn below surface.
Alan