Additionally, most car companies have figured out how to make the final drive robust and problem free because they are aware of the forces involved with the ring and pinion bevel gears – except for Ferrari. They used a deep groove ball bearing and sliding inner race roller bearing that cannot handle the axial loads on the pinion shaft. Other companies used tapered roller bearings that can handle a tremendous amount of this fore-and-aft thrust while spinning with ease but the Ferrari style comes apart and destroys the gears.

My solution is to replace the sliding inner race roller bearing and the deep groove ball bearing with a pair of tapered roller bearings. This photo is a 250 GT Lusso center section with the “chicklet” style limited slip differential. On some axles I’ve install tapered roller bearings to support the differential but on the later axles there isn’t much room to install this type of bearing and I have found the original ball bearing set up to be adequate. I have done this conversion to many cars that have gone many thousands of miles with no issues.

Final drive Ferrari

GT Ferrari 250 Axle Center section

This transmission out of this 250 shifted well but had the typical severely worn synchronisers so I was prepared to perform the “normal” repair of cleaning, inspecting and replacing the end bearings and synchros. This trans had been run without oil for a long time and the bearings in the photo were so wiped out that there was about .020″ clearance between the gear and bearing where there should only be about .005″. How did this thing work at all?

250 GT transmission overhaul

Transmission overhaul bearings

Bearings Ferrari transmission

After taking it apart I couldn’t see much wrong and the synchros seemed used but not totally worn out. Like many other car manufacturers, the synchro for 2nd and 3rd gear is different than of the other gears and maybe someone put the incorrect part on the gears.

It wasn’t until re-assembly that I noticed that the dog teeth on first gear were chipped and remembered that the slider (operating sleeve, shift sleeve) for 1st gear has asymmetrical internal teeth to meet up with the corresponding dog teeth on 1st gear. The operating sleeve can be reversed  so the side that should engage 1st gear is incorrectly jamming into 2nd which makes engaging into either of these gears while under motion nearly impossible.

Lucky for the owner, I located a shop who can replace just the dog teeth (engagement teeth) for short money without having to spend the $2000 that Porsche quoted to get the parts. We sent 2nd gear  from a 901 transmission to the same guy for repair and cannot wait to see how they look and more importantly how they perform.

Transmission repair Porsche 911, 915, 901

901, 915, G60 transmission for Porsche repair

The blue 330 GT 2+2 that came in earlier this year ended up needing an engine overhaul but I was fortunate to be able to drive the car prior to breaking it down. The transmission shifted perfectly but on acceleration/deceleration the shift lever moved back and forth significantly. As some may remember, this same thing happened to a 330 GTC transmission a few years ago and it turned out to be a loose ring nut on the main shaft.

I was certain that we had the same issue on this 330 2+2 and when I took off the top cover, it was instantly obvious that the ring nuts at the back of the main shaft holding the gear cluster on were totally backed off. They are doubled up to jamb together to prevent loosening plus there is a locking tab for extra protection on backing off… but still, someone managed to mess this up. Thankfully no damage was done to the internals.

Huge Ferrari transmission

Early Ferrari 5 speed aluminum transmission

loose ring nuts on a Ferrari transmission

Transmission

Gears for mainshaft and layshaft

but the gears and spacers are all good.

I just ordered ever  body rubber seal, full front suspension overhaul kit, assorted specialized trim screws… boxes and boxes of stuff to make this car as new and the order was under $3000.  Incredible what you can buy and how inexpensive the parts are compared to Ferraris and other cars that we typically work on.

The flywheel was sent off to be under-cut and the carburetors are getting the royal treatment from Karl.

SC Porsche Coupe

This 304 stainless steel is great stuff, very workable, machinable, weldable.

To see the ones that came off the car click http://www.ferraricraft.com/2009/12/corroded-ferrari-water-pipes/

Fixture to reproduce water pipe

Reproduction water pipe in stainless steel

The big difference between the wheel nuts on current race cars and on vintage Ferraris? The method of removal. The current race cars use a large diameter socket, while the vintage cars have 2 or 3 ears extending off the nut. The method of removal is repeated smashing of these tabs by the standard equipment lead hammer found in every Ferrari – it isn’t just for fending off would-be attackers. The lead hammer packs a punch, and the softness of the lead won’t mar the finish of the nuts, just watch out for your fenders on the back swing. At RPM wheels are removed frequenly enough to destroy these hammers, so we have a mold to recast the hammer head.

On to the nuts themselves. The word “smontare” seems to be on nearly every nut. It’s meaning? In Italian, smontare means to dismantle, or slang to “knock-off” which makes great sense, that is how the nuts became known as “knock-offs.

One pictured knock-off has the word “destro” cast into it. The meaning is “right” – it holds a wheel on the right-hand side of the car on. The opposite is “sinistro” of which we have none pictured. The reason for having right and left nuts is because they are self-tightening. You can literally spin a knock-off on gently, go for a drive, and it will be tight enough to require the lead hammer for removal when you return. Not bad.

Check out the gallery below, click to enlarge images.