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Re: Diffs combined with the sports gearboxes

Posted: Tue Aug 30, 2016 11:33 pm
by petroscf
Well, forgive my ignorance, but, the c/r still has 3 main "racing" gears (2nd-3rd-4th) very close to each other whatever diff ratio is used, no?
The O/d has these gears a bit further between them, I mean from one to another rpm drop more than with the dogleg
So I guess the longer diff compensates the c/r mainly concerning 5th gear which here is 1:1, but even so the gear box remains really fun to drive?
I have seen a later table of ratios in E36 cars: almost all had very long diff ratios (compared to our E21s) for the engines. But none had an O/d gearbox
All of them used direct gearboxes -and iirc 2nd and 3rd were quite similar to our c/r boxes, not to our o/d
Of course I understand that such comparisons are not good examples, and also, aerodynamics in E36 is much better
The reason I fitted the c/r box is mainly because I found one when I was doing the engine project, and I decided to buy it as I know it is something rare
I know I might have almost the same result if I kept the o/d with the 3.64 I fitted (the lsd I bought from Nas)
I was just thinking whether it is better to have the dogleg and a bit longer diff ratio than 3.64

About the 3.36 now: iirc, in the catalogue I did not see 3.45 at all
I saw all of the other mostly used ratios and some more, much shorter, I guess for racing reasons
But I was thinking, that 3.45 is 11-38 and 3.36 is 11-37, so only a bit longer, so maybe slight difference? Couldn't it just be that bmw replaced 3.45 by 3.36 having, perhaps, decided it is better?

Re: Diffs combined with the sports gearboxes

Posted: Wed Aug 31, 2016 10:36 am
by Mihajlo
3.36 is a e36 168 diff option
it is never been an option in e21

e36 gearbox has 5th gear 1:1 and that's why they used "longer" diffs + stronger engines
e21 gearbox has 4th gear 1:1 and 5th overdrive

Re: Diffs combined with the sports gearboxes

Posted: Wed Aug 31, 2016 12:10 pm
by petroscf
Mihajlo wrote:3.36 is a e36 168 diff option
it is never been an option in e21

e36 gearbox has 5th gear 1:1 and that's why they used "longer" diffs + stronger engines
e21 gearbox has 4th gear 1:1 and 5th overdrive
E21 c/r gearbox has 5th gear 1:1
If you look up under bmw classic parts, they sell 3.36 crown set uner E21 323i section. End they also have all the other ratio options, except the 3.45 (which was the official one)

Re: Diffs combined with the sports gearboxes

Posted: Thu Sep 01, 2016 8:52 pm
by Mihajlo
that's true, but I was talking about regular gearbox.

my fault

Re: Diffs combined with the sports gearboxes

Posted: Thu Sep 01, 2016 10:33 pm
by niske
I have read somewhere that 323i E30 with sport gearbox had slightly longer final ratio compared to one with regular 5 speed gearbox... So maybe thats not a bad idea...
@petroscf
Like you said earlier the main point of sport gearbox is less rpm drop on gear changing...