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Discussion Starter · #1 ·
Did the brakes up a while ago and, on testing them, heard a hell of a metallic growling when the brakes were applied hard. Thought it was the brake discs doing something bad. Turned out to be the gearbox mount was allowing so much movement that the engine was tipping forward under the deceleration and the gearbox was lifting to the point where the driveshaft was rubbing on the tunnel.

Put in a new gearbox mount. It is a 74 model GTV 2000 so I presumed it was a late model requiring the late mount (part no GB024 at Classic Alfa) with the offset hole rather the early mount (part no GB023) with the central hole. Because the drive shaft had been hitting the tunnel we mounted it with the hole to the top so the gearbox sat low and away from the tunnel. Worked OK for a while but once the rubber flexed a bit the pin, having very little rubber under it, would bottom out within the mount causing a hell of a thumping every time I accelerated or went over a bump.

Had a look around this forum and at repair manuals and determined the mount was upside down. The offset hole should be at the bottom to allow more movement under the weight of the gearbox.

Took it out and turned it. Now looked the same as the manual etc. Then it got interesting. Jacked up the gearbox with mount fitted so that I could bolt the mounting bracket back to the chassis. Still had about 6 mm to go when the drive shaft hit the tunnel. That’s where I had started.

Long story short, I made up a couple of 13mm thick spacers and inserted them between the bracket and the chassis. Now works fine.

However, I don’t think I should have to needed to do that. What went wrong? Should I have had the early mount?

One last thing. I had to put in longer bolts through the bracket, spacer and into the chassis. As it is an Italian car I expected them to be metric 8mm dia. Turned out the ones that I took out were 5/16 UNC. Managed to find some longer ones and put them in. Should they be 5/16?
I have known some less than brights in the past who have used muscle rather than brain and have cranked a wrong nut onto a bolt so hard it overcame the difference in thread pitch between 8 mm and 5/16 and basically tapped a new thread. Has this happened to this machine in the past?

'66 Sprint GT, '67 Duetto, '70 BMW 2800CS
13,065 Posts
I can't explain those two issues. A 1974 Alfa would use the offset transmission mount, and it would be installed with the offset at the bottom - not the top. The four bolts that secure the transmission support to the body should be 8mm - not 5/16".

Is it possible that whoever buggered the metric threads with SAE bolts also somehow changed/modified the transmission support? Perhaps substituted one from an earlier car?
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