GTE Thowout Bearing
I’ve been sorting out Tom Wilson’s GTE these past several weeks, and I noticed a noise from the throw-out bearing whenever I depressed the clutch. I didn’t want to be the guy to tell him the transmission had to come out to investigate, especially since all the parts installed were new from a previous shop. The noise was a high pitched scraping noise, and happened about 80% of the time when I depressed the clutch, but didn’t feel like the bearing was going bad.
We decided since the interior was out of the car, the speedometer gear was getting fixed, and the drive shaft was out, now was the best time to pull the transmission to take a look.
At first I didn’t find anything wrong, and everything looked and felt smooth, but since the only thing that could be making the noise I heard was the t/o bearing, we decided to install a new one. When I pressed the new one in, it felt worse than the other one! On closer inspection, I found the collar of the t/o bearing assembly was touching the inside of the bearing case. Although all the other dimensions were the same, the sheet metal case of the second bearing had a smaller ID. I had to machine nearly a millimeter of material off the inner sleeve so it wouldn’t touch the casing.
This was one of those times when pressing a new throw-out bearing in place should take about 5 minutes took a lot more time because Ferrari parts can be tricky. Suppliers get parts from different sources, and specs are different so we have to check everything and know which parts work and which parts don’t. In this case it wasn’t an inferior part, but just a different part that fit differently. Now everything worked smoothly and without contact!
Once I fixed the contact issue with the new bearing, I went back and looked at the bearing I took out. I was willing to bet money that was the sound I heard when depressing the clutch. On one side of the bearing case I could see the black oxide finish on the sheet metal.
On the other side, I could see a bright spot on the metal where the throw-out bearing assembly was touching. When I had it in my hand, I couldn’t feel the contact, but I guess when it was installed in the car pressed against the clutch, it made contact. I felt better knowing I found the source of the noise and it wasn’t just my imagination!