Diff project

Thanks..

 

Post # 66

 

One side of Paul Newman's billet Diff Carrier:
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and the other side (with no weld -- in Don's picture in post #66 the side with the weld is the side not shown):
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and as installed in my TR by Rifledriver (Brian Crall):
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The .002" diameter wear on the LH bearing journal of my original TR Diff Carrier (which still baffles me some how this could ever happen as, if the torque needed to spin the inner race of the bearing on the journal is so low that it is lower than torque needed to spin the bearing rollers, the wear should be nil. The pinion driving action does force the ring gear away from the LH bearing so the LH bearing being unload seems reasonable, but thought that interface between the bearing and the journal would be well lubricated):
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Interesting indeed! Thanks for the pic.

 

All those diff stories are very interesting :
Ferrari of SF told me they never had to change one and my well respected indi roselli also say it’s not as common as it is.
I bought Newman’s as a preventative measure for mine.


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Now you can go out and drive the piss out of it! You know dump the clutch, spin the tires

 

See post #31. That said, the fact that the diff was upgraded at some point in the 512TR is evidence that this retrofit is potentially a good idea. Is Newman making his diff again? He was out last year.

 

He did a batch of 5 for a group buy on fchat
Fir sure I it’s a weak spot, I wish we knew précise stats on the failure.
Reminds me of the PTU on the ff.


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I removed my differential yesterday afternoon, a relatively straightforward job. Gear teeth look perfect. As for the unit itself, the welds look perfect as well. The Newman unit will go in anyways, with new LSD disks. The interesting thing will be figuring out how to remove the bearings from the unit and the races from the carriers. Heat and a puller I guess.

 

why remove? I think you will use new bearings

with heat they just will fall out. I put them in an old oven and hear when the races fall down

 

I need to remove them to open the differential case and remove the gears and the inboard drive axles which protrude from the differential, no? I do have all new oem bearings and races.

 

sorry, have not remembered that you use paul´s diff, there are no internals in. that is why I until now used 4 times modena diffs

 

From what my mechanic told me, a puller is all you need. The kind that has a tapered/beveled set of jaws (?) that slips under the bearing race and as you tighten the tool it "wedges" the bearing off and doesn't damage it. Similar to a tie rod removal tool I guess.

 

and how you want to get the bearing out of the aluminum housing? there is no space for a puller

 

when the diff is out of the gearbox, both sides of the diff are exposed to allow access to remove the bearings....

 

I plan to heat the left and right side differential carriers to get the races to (hopefully fall) out. I am not sure which puller will remove the big bearings from either side of the differential case, but I have a few to choose from. Today and tomorrow will be spent on the oil pump chain, tensioner and water pump before I remount the engine onto the top of the transmission case, so I have a little time to think about the differential before it goes back in.

Anyone know how many NM of torque to use on the 17mm nuts which tighten the engine case studs down through the transmission case?

 

I´m not talking about the bearings on the diff, I talk about the bearings in the aluminum covers

 

never used a torque meter for this. tighten hand-tight. so about 50 to 60 NM. the 2 nuts behind the flywheel not need so much.

 

Ahhhhh.
OK, my diff and transmission shaft went to the X-ray company this a.m and all is well. X-rayed and magnafluxed with o abnormalities, cracks, fishers, nada. And the report written.
So that makes me feel pretty good about putting it back in the car. Considering the way the car is driven there shouldn't be any problems down the road. And if there is I won't admit it ;-)

 

My theory is not if, but when this blows, could be 100k miles 30k or 130k..

 

life's a risk...

 

Indeed
My diff still stock and I have 275 rears, lol.

 

A friend who has run his own independent Ferrari shop in Canada keeps information on this subject; he has checked differentials in 13 customer Testarossas so far, and replaced one unit because a tiny crack was visible. I pulled mine last week and it seemed perfect, but will replace it because I bought the Newman part a few years ago in anticipation of this major service. If 1 in 14 Testarossas face this issue (not a scientific conclusion by any means), it may be enough for me to replace it out of an abundance of caution, although with increasing future mileage on the Testarossa fleet, that 1 in 14 number could change. I also have a BB but have no intention to replace its differential, as I have heard of few failures and it is driven so infrequently and gently.

Still, the process of replacing it has taught me a lot about differentials in general and my TR in particular, so I am glad I did it (and I can take some comfort from knowing a potential weak spot was addressed).

 

It's a sketchy design and never feel bad about "fixing" that.

 

Making progress today. Differential assembled, bearings installed on differential case and in carriers. Does anyone know the proper orientation of the hole on the passenger side carrier?

Should be able to check the bearing preload tomorrow.


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