Upgrading Early Testarossa Differential

Here is my 2 cents after going through this on a Boxer transmission which is the same basic design as the TR (welded differential).

The basic problem on the Boxer and TR transmissions is that the differential "spyder gear set" is a welded unit. The weld may fail putting pressure on the differential side carrier blowing it out. The transmission case is generally OK and the ring and pinion is generally OK.

In my case it was not. But that's not typical.

SO THE SOLUTION IS TO INSTALL A ONE PIECE DIFFERENTIAL, similar to the one used on the 512M (or maybe the 512TR had these also) for around $3,000. But that is just for the part.

That being said. What happens when it breaks is that you can either send the transmision to someone like Rod Drew in CA for repair or buy a reconditioned one from one of the various parts suppliers.

An early TR case will not fit a Carbed BB. The oil pick up points are different but potentially could be modified.

If my car was running fine I would just not worry about it. When it happens it happens and I don't think the risk/reward of spending close to $20K is worth it (you will do other things once you are in there); new syncros, bearings, etc.

Again, when the differential breaks and takes the transmission side cover with it the ring and pinion, case , gears are generally OK, but sometimes not. So I don't think you gain a lot by doing this as a preventative measure for something that will probably never happen.

My one caveat is that these cars are just starting to age so maybe as more miles are put on we will see more of this.

I do not think this is a function of gear oil. I think it is just a poor/weak differential design. But as a data point I was running Royal Purple when my differential went out and had 53,000Km/33,000Mi on the car which I believe to be accurate.

I purchased the parts through T Rutlandsin Atlanta and Rod Drew in Ca did the transmission work. They do a lot of these, especially for T Rutlands.

To me its a lot like sodium valves stems. Yea they can fail, but taking the engine apart, as a preventative measure, is not cost effective in my opinion.


Regards,

Drew Altemara

 

Can someone post a pic of the 512TR diff please? Even a parts manual pic will do. I want to see the differences as well as what is required to make the change. Drew, what route did you go for parts? OEM or upgraded?

P.

 

Paul:

I ended up sending my toasted Boxer transmission to Rod Drew in CA. Ted Rutland sent a doner TR transmission. We took the TR parts and put them in my BB case. Remember, my ring and pinion and and gears were toast;not typical.

I purchased a new single piece differential from Ted along with new syncros, bearings, special nuts, side cover etc The description on the invoice says "DIFF, ASSY, T/R UPDATED"; part number 155099 (which may be a T Rutland part nmber). T Rutlands has done a lot of these with Rod Drew and I trust them that this was the right part for me to use. I paid over $3K for the differential.

Total cost for all this was under $20K for the transmission plus another $10K for an engine out major service; belts, tensors,carbs, water pump, hoses, freshen up AC, and a couple of other items, "while we are there" and I have around $30K in the car.

Hurts, but after 20 years of Ferrari ownership this is the only real problem I have ever had.

Anyhow I like the car and intend to keep it and use it.

 

Jay, let me try to answer your questions based on my experience.

1) The upgraded differential is just over $3K. There is another $2K in syncros, special nuts, bearings, etc that you will most likely want to do if the transmission is split from the engine. The transmission labor was $2.5K.

Remember, that in my case the ring and pinion and gear set was toast. So this was an engine out and seperate the engine from transmission. However, the labor cost for just replacing the differential and syncros would probably be less. But still in the same ball park.

2) I do not know if the differential is bound to break or not. I wish I could give you the probability curve. I can tell you, that after speaking with Ted Rutland his feeling is that it will eventually let go but when or if ever who knows. Maybe its just how well the things get welded that sets the probablilty, I just cannot answer this.

I can provide this information though. When the differential lets go it usually takes the differential side cover with it but not the ring and pinion or any of the transfer gears. My point is, there should not be much additional cost in the preventative maintenance vs. just seeing if it ever breaks and paying to fix it. With the exception of question 3; below; can it be done in car.

3) In my case this was an engine out, seperate the trans from the engine. I do not know if the differential could be replaced with the engine still in the car. I have seen some threads where some people thought they could be. The one problem is that I cannot see how you could get at the differential without the case opened up and then insure the ring and pinion are properly aligned. I am curious about this also. But do not know. Hopefully someone more knowledgable will answer.

4) I don't know who was the manufacturer of the upgraded differential that T Rutlands supplied. But they have done a lot of these and I trust them completely in this matter. See my prior post for the part description and part number. If curious, I'm sure Ted Rutland would tell you.

Sorry I cannot answer them all. But this was my experience. Hope this helps,

Regards,

Drew Altemara

 

does the 512tr have a ONE PIECE DIFFERENTIAL?

 

The outside case of the 512Tr diff is one piece billet vs welded on the Bbs and Tr, according to the Cali rebulders they get 15-20 broken diffs a year with these cars, with a $3k new diff you are still looking at $10k+ in labor and other parts for the engine out and trans set up, unfortunately its not a simple bolt in replacment as the new diff must be set up and shimmed properly with the R&P which is a major pain.

I'd say drive it till it breaks the same with the valves, Ferraris are never going to be fail proof for major repairs no matter what.

Unfortunatly with issues like this and the soft fragile bodywork this has caused me to rethink my driving habits for my BB to now a seldom driven car replaced with the 355 for the one to drive.$30 k is still substantial for a repair no matter what.

 

Check out this post (and the entire related thread)

http://www.ferrarichat.com/forum/showpost.php?p=135980412&postcount=111

 

I believe that required an engine out operation.

 

I had a one piece diff installed with new syncros for about 10k and a major service for another 5k at Francorchamps in Calif. I pulled the motor/trany and shipped it to them. I wonder if I should have done the water pump also......oh well. Also, I remember during the conversation that some years of cars had a problem with gears that crumbled?! and they made gearsets. Fwiw.

Jeff Pintler
89 348tb, 86 TR

 

Knowing how I drive cars (very hard) I would put the money into upgrading as the break would most likely happen under hard driving. Also, when diff’s go, there is always the chance the rear end will lock up. Not a big deal at 15 mph going strait, but a very big deal and potentially catastrophic when cornering at say 70 mph or above.

As for the sodium filled valve analogy, I had the Valve failure. It would have been so worth the preventive cost savings for me to have removed the heads and fixed the valves vs. what happened. I was not aware of the valve issue until after mine failed. And again, I drove the car really hard (valve failed at 8000 rpm's). Someone who keeps their 308 under 6000 rpm’s would probably never see the failure.

It really is an owners preference based on driving style.

 

8000rpm?, I take it that your 308 had no limiter?

 

Carbed 308's have no limiter and mine has also seen 8000rpm. As for the diff upgrade on a boxer it is a wise investment while an engine out is being performed. Its all I could think of on my latest outting with the club climbing up a steep twisty road winding her out. I wondered to myself...what if?...it didnt happen but it would have been messy and expensive if it did grenade. Ill be doing mine whether it breaks or not in a couple of years.

 

Now here is a good reason to short shift. <<

 

Buy the parts now if you have the money laying around. No telling if you will be able to lay your hands on one when you need it.

 

A friend of mine suggested an aftermarket alternative made specifically for the upgrade, says its one piece billet, anodized and all (not that you can see it in the gearbox). He has installed a few of them and it rings in at about $850 cdn taxes in. Ill pass on the TR upgraded version since the aftermarket one is probably better.

P

 

Who makes it?

Do you have any other info on it?

 

I agree with the idea of stockpiling the parts for the engine out service, especially since I am running modern rubber. Who makes this aftermarket diff?

 

Ill let you know asap, Ill call my buddy now.

P.

 

The differential carrier is $4500cdn as apposed to $5000cdn for the 512TR factory part, sorry for the price error. The name is Modena Engineering in Austrailia. Google it.

P.