Diff ratio

If you mean just the differential gear set, the documentation indicates that most are 45/14, but some (e.g., late CH) are given as 61/17 (but this OM data set has an obvious calculation error so doesn't give confidence).

But the transfer gear set also varies for year/version, so for the overall engine-to-rear wheels relationship, you need to do a (transfer gears) * (gearbox) * (diff) calculation for a particular year/version -- and it's quite "tall" in 5th gear for all of them compared to "normal" cars -- ranging from 2.720:1 to 3.036:1 (correcting the late CH calculation assuming 61/17 is correct) -- which it needs to be to get to 300 KPH

 

I am glad to hear that you are thinking of that issue, so many don't when working on the transfer gears and/or the cam belt drive gears (if so equipped) -- and they should!

 

OK, this might sound like a stupid question. What do you mean by hunting and non hunting?

Does it concern a wear pattern on gears that always mesh with the same tooth and root?


Ago

 

Exactly. Because 14 and 45 share no common divisor, (eventually) every tooth on the pinion gear comes into contact with every tooth on the ring gear (so random reassembly relative to each other isn't an issue). The 308/328 driven cam belt gear has 36T and the driving crankshaft gear has 27T -- so an individual tooth on the driving gear only touches the same 4 teeth on the driven gear. Same issue for the transfer gears with 27T-28T-30T -- no problem for the 27T-to-28T relationship as they share no common divisor, but, on the 28T-to-30T gears, 1/2 of the teeth on one only come into contact with 1/2 of the teeth on the other so best to not alter their relative phase.

Even keeping this relationship correct (when necessary), there's still a little dodgyness to reusing gears because it is impossible to remount them in their exact same locations relative to their corresponding axes of rotation (when you get down to the micron level) -- i.e., just the tolerances in the new bearings may move the axis of rotation for either gear a little from where it was, and, since the pinion gear and pinion shaft are an integral unit, you can't mess that up, but it's best to keep the relationship between the ring gear and what it's bolted to the same (if you are reusing both of those components).

 

Jeeze Steve..... My resolution for this new year is find a question that you cant answer.
Its going to be a tough one because I wont know the answer either to know if you are right

Happy new year

P

 

Happy Nwe year to you all !

Steve, I hope that "so many" should leave this precious work to the few EXPERTS ... and don't try to save money.....

In the end ... as allways ... they may pay a very differnt price ...

Please leave it to the real specialists like Steve or Cavalino or ... xxx ...

 

as I know only the swiss versions have such different ratio.

the swiss meassured the exhaust noise during acceleration in 3rd or 4th gear. and with the lower ratio from 14/45 the rpm have been to high and so the noise to loud. but why they changed those diff ratio and not the ratio from the main gears ( so from the clutch down to the gearbox ) I don´t understand.

I put in as you see in the pictures a little different gears for the main gear box ( pirmary gear box or how you say to this??? ). so it is always easy and fast to change the ratio if I go on a hill track or a round track.
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He Romano, please show us MORE ... ... for instance your exhaust system ...

 

on my car there is no real exhaust system:

only tubes with diameter of 70 or 80 mm from the turbos and on each side then a silencer of 100 mm diameter. that is all. also the wastegates not to forget. pictures will follow the next days.

because I remember from motorcycling: loud pipes save lives

and a ferrari has to be heard discreetly but firmly

 

I just had a look on my comp here and found those:
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