Diff ratios

[randomspeedfreak]

which diff ratios are people running on the m42 box?

im going to get an lsd and have been offered a 3.73. should i go for that or hold out for a 3.64 or a 3.46?

whats everyone else got and how does it go?

cheers

[JGTI]

I guess a 3.73 might be the right compromise for a quick car off the line, and a useable car!

I'm on 3:91, and it's always buzzing

[randomspeedfreak]

whats the 3.64 saying boys? anyone got a 3.46?

[craigieeb]

Im using a 3:64 and it's spot on as an all rounder,
But I wished id used a 3:91

[E30BeemerLad]

Im using a 3:64 and it's spot on as an all rounder,
But I wished id used a 3:91

I'll swap you then

[rich318i]

i got a 3:91 but rev's silly

[hotrodrick]

Im running a 3:91 on my m52 with m42 box and I find it way to short. Need something a bit longer for a daily car. Fun off the lights though!

[e30-EVN]

I'm using a 3.64 on my m52 with m42 box...... Imo a 3.91 would make take off quite fun but way to buzzy on duals or motorways!

That said a 3.46 would be to long, with the 3.64 I feel its the best all rounder. Not exactly shy off the line either, and 73-75mph @ 3000rpm. Win win

[Sanchez]

Really depends on your driving style/comfort etc.

3.91 if your not too many motorway miles and lower ratio if your around town or like to give it the beans on the strip/track.

[Hoobs]

My e21 runs an e12 LSD with a 3:07 and standard 323i box. I plan to fit a C/R gearbox eventually but the longer gears haven't made my car any less fun to drive and it has enough grunt to pull hard through each gear. I quite like not having to snatch a gearchange quite so quickly too!

[shabalake]

I've got a 320i gearbox on mine not sure what diff i got but at 70mph its around 3400rpm i looking for somthing longer 3.64?

[BATTS91]

i have m50 with e36 box and a 4.1 diff ive only test drove down the road and its mental going to try 3.64

[redcar]

i have m50 with e36 box and a 4.1 diff ive only test drove down the road and its mental going to try 3.64

I thought that if you use the e36 box you need something closer to a 3.0?

[hotrodrick]

What was the 3.91 lsd originally be fitted to?

[redcar]

325i facelift sport

[DanThe]

http://www.realoem.com/bmw/partxref.do? ... &details=1

[Jimbob]

Just been playing around with gear ratios here http://www.endtuning.com/gearratios.html

It claims there's 350rpm difference between a 4.10 and 3.64 based on an M42 gearbox @ 70mph, I thought it'd be more than that.
Building a 4.27 LSD seems a bit more realistic now as it looks as though it'll do 3300rpm @ 70mph.

[Hoobs]

I'm running a 4:1 and was expecting to feel the difference a little more than I do. It does feel better on initial launch but that may simply be that this diff is working better than my old one did?

[deanocool]

i have m50 with e36 box and a 4.1 diff ive only test drove down the road and its mental going to try 3.64

batts i had that symptom. i had a 4.10 that had no 1st or 2nd. i bought a 3.64 but it was still way ott and had 2nd but no 1st. then i got a 3.08 of danthe and its virtually spot on. its a tad light which makes for good acceleration and still has a decent top end. if you want a factory drive i would recommend a 2.93. i wouldnt bother with a 3.64 for a road car on an e36 box, better on a track really.