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Triumph TR6 - Grinding 3rd Gear

I had my '76 tranny rebuilt $$$ over the winter because it was grinding on a shift into 3rd gear. Since I got the car back, I have done some additional work and taken it fairly easy while I'm getting to know my new car. Over the last few weeks, I have been driving a little more aggressively, and to my disappointment, I've discovered that 3rd still grinds on a "quick" up and down shift. I think it also occurs if engine speed is still above 3 grand. If I slow down my shift by a split second and let engine speed drop, the shift is smooth.

I paid a lot of money to rebuilt the tranny, gears, sync gears, bearings etc etc. The problem I have know is if I bring it back under warranty, the workmanship is covered, but the parts are not. If they failed, I'm back into an expensive repair.

Any advice on what may be happening? Did the mechanic miss something, is the oil too thick, can I afford to have the mechanic take another look?

What are you running gear-lube wise?

Rick O.
Rick Orthen

Boy I hate being so public about how little I know about my car. I let my mechanic put it all back together again and trusted him with all the choices. Are there choices?

I've read articles and posts that state regular gear oil is really too slick too allow syncronizers to work properly, and that could be the source of your crunch. Redline makes two manual transmission lubes that work well - the MTL, which has a reduced amount of "slip" additive, and the NS, which has none. I run a 50%-50% mixture of the two, which helped, but didn't eliminate my crunch shifting fast from 1st to 2nd.
Brent B

Hi Mati,

Who did the work?

Why are the parts not covered? If they have any experience on these transmissions they should have obtained the parts themselves? From a known to them supplier.

3 grand is not race shifting should not be a problem.

I agree with Brent likely Sincs but if you have not changed the oil or using recomended, still repair shops problem.

Don't know the situation but I would imediately take back to mechanic and explain the problem. See what they think. Ask the fellows name and write it down as he explains. Or get them to give a written report if they will better yet.

Don't commit to anything before reposting.


Bill Brayford

Mati- I would take it back ASAP and ask them to check it out. Please tell them if they supplied the parts they should be liable for all repairs under a stated warranty. If they balk at this I would suggest you report them to a Canadian BBB. If the reason you took it in was for the same reason your bringing it back,they didn't fix it.
Don K.

I concur with Don - the fact of the matter is a freshly rebuilt Triumph gearbox should not grind gears. Unfortunately for you and the shop you need to pull that tranny and do it again.


John Parfitt
John Parfitt

Thanks guys, it's booked for Saturday. I'll keep you posted.


I just returned from my holidays, I left the car with the garage during my absence. The tranny was pulled and another set of syncro gears were installed - no charge - and it's as smoooth as I could have every hoped. Nice to see that there are some shops out there who care about their customers and stand behind thier work.

There are or were bad syncro being sold by most every supplier over the last several years. The syncros are too thin.

Syncros have 6 tangs sticking out axially.

Three tangs are rather large and are used to lock the syncro into the shifting hub. When the shifting hub rotates, these tangs force the syncro to rotate at the same speed.

The three smaller tangs are the problem. If the thickness of syncro at these tangs is less than 0.4098" the shifting hub hits the mating teeth before the syncro. The 0.4098" thick syncro is the thickest syncro that I have had problem with. I really don't know what the minimum is. I can definately tell you that if your syncro is not thicker than 0.4100" you will most likely have problems.

The syncro is suppose to get the shifting hub and gear rotating at the same speed before the shifting hub comes into contact with the mating teeth. If the syncro is too thin, it eithe does not hit the gear or it hits the gear too late and cannot get the speeds to match at the same time.

In recent years, I have been reusing syncro because the aftermarket ones were so bad. But, this year I have been able to buy some very thick ones from Moss. If you see a thick one next to a thin one it is very obivous. The thicker ones are probably 0.060" thicker.

Good luck and I hope the thin syncros are not your problem.

Brent Kiser
Minnesota Triumphs
L. Kiser

This thread was discussed between 16/06/2003 and 28/07/2003

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