Vibrating gear shift.

Hello
Just finished placing my new gearbox on the 1990 testarossa. Did a full major while in there.2nd time in 3 years.

Everything seems to be running great and shifts great as well.

We replaced the crown and pinion with a set I had made, because the set in the other gearbox was making noise.

Test drive shows all gears going in nice and smooth, not popping out of gear. The only problem is 4th gear. When it is selected the gear shift vibrates slightly and makes a vibrating noise. You hold the gear shift forward and it stops.

Because we have the old gearbox on the bench, after trying to fine tune the linkage with no success, we examined the gearbox to get a clear picture in our minds of what might be going on.

This is our theory.

When we tightened the selectors on the shift rails, once gravity had centered them ,we tried to tighten them with equal spacing because they were touching. This pushed the 4th and 5th gear selector closer to the gears. Therefore when the gear is selected, the selector gets close to the turning gears and just touches them.

We had turned all the gears prior to installing the box, but it could not have been detected. We would not have been able to detect a small rubing while turning by hand. It only shows up at speeds consistent with 4th gear.
I pulled into the driveway and shifted to 4th, crawled up the driveway and it did not make any noise.

By trying to space them, we think we pushed the 4th and 5th selector too close to a gear (second gear).
The selector's bolt fits into a groove on the shift rail but there is still some play, and you can tighten it down in different positions on the shift rail despite this groove.

When we look closely, selecting 4th gear causes it to get closer to the gear, while selecting 5th seems to get it further from the gear. The reason we only hear it in 4th.

Before we take the exhaust manifolds, motor mount and side cover off, I thought I would ask if anyone has had a similar issue and if there are other possibilities for the noise and vibration.
Thanks. Brent.

 

Bought the car and it had a worn crown and pinion gear. Very sharp teeth. Making lots of noise.

Pulled the engine, bought an entire gearbox from Trutlands. $12 000. Payed $100/hr for 5 hours for their tech to inspect it. Installed. Howling gears when coasting.

Had new crown and pinion made, installed in original gearbox and just put back onto the car.

So I have an extra gearbox at this point. I examined the gearbox and tested the gear pattern and the pinion is set too deep on the one I got from Rutlands. . Should have looked before installing it originally but that is why I paid the extra $500 so I could be confident it was set up properly and just install it. John at Trutlands charged me $500 to have their tech look at it, and when I spoke to Ted, he : "had no idea what I was talking about". i.e. Charged me $500 and never had anyone look at it.

The bright side is I found a gear company who reverse engineered the gears for me and they work great. Have sold 3-4 pair to fellow Fchatters. Around $5000 as apposed to buying a new gear box or $10 000-$17 000 for a crown and pinion from Ferrari.

So that's the story. Almost finished, just need to clear up this last problem.
Thanks. Brent.

 

Took the cover off and found that the selector was indeed rubbing up against the gear.

Problem solved and internal linkage adjusted great with the side cover off.
Brent.

 

We kind of did it step by step.
It's not super difficult but you have to be careful.
Once you remove the clutch and flywheel, I believe you are just left with the rear engine mount that is mounted to the gear box. We made marks on the clutch and flywheel to ensure it was installed properly again.
You will have to remove the quill shaft once the clutch housing is off. Just pulls out.

There are (2?) nuts that hold the gearbox from inside the clutch area.

You have to take off the all the manifolds, which you most likely have already done.

I believe one of the side covers where the axles are has a nut at the top of it that secures the gearbox to the engine.

You have to remove the front gearbox oil pump cover (a few seals in there that you can replace). This part is above the shift rod seal that we were talking about replacing.

There is an oil drain pipe at the front and a few hoses at the front and the sides. .

Just look at everything before and while you are lifting the engine off.
The gearbox usually breaks away but usually at one end more than the other so you could bend some studs. Just go slow when lifting. It will just break away. No fancy tools required.

There are 5 oring seals on the bottom of the engine that may come off or stay with the engine. Make sure they are back in place prior to re-assembly.
There is one o-ring on the side sealing surface. (see parts manual for more accurate info)

So in summary, it is just loosening and removing a whole bunch of things. I tried to mention the more difficult nuts. If you are removing something and it is not coming off easy. Double check that there aren't anymore nuts and bolts before prying.

I've only done it twice and I am writing this from memory so if you can find a thread with more accurate info that would be great.

By the way, what did you find in the gearbox. Can you post pictures. I have my spare gearbox off the car that I could compare for you....it's just 3 hours away right now so I would have to take pics next time I am up there.

Don't get discouraged. Everything is fixable on a TR in one way or another.
Brent.

 

I'm trying to post some pics. Not great shots but at least something.
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