S50B30 in a E30 Touring, which gearbox

[vanos]

I got a S50B30 and matching gearbox to go into my E30 Touring, is it best to keep the gearbox or can I fit my 325i gearbox to the S50B30 engine, I have an LSD from a 325i sport mtec 2, it's a 3.64 ratio.
If I use the M3 gearbox will I have to change the LSD to a different ratio'd LSD ? and what would be the best LSD ratio ?
If I kept the 325i box I can keep the LSD and keep it the same.

[Gunni]

The 3.64 will be kinda short for the 5gear S50 box. But will still be nice to have for acceleration.

I used to use a 3.25 diff with my S50 and I felt it was the ideal diff ratio.

[vanos]

The 3.64 will be kinda short for the 5gear S50 box. But will still be nice to have for acceleration.

I used to use a 3.25 diff with my S50 and I felt it was the ideal diff ratio.

Thanks Gunni, cant use the 325i gearbox then ?

[Gunni]

Only with a M20 flywheel and clutch combo I believe as the 240mm pressure plate is to large for the M20 bellhousing.

[e21Jason]

Also the 325 gearbox will sit at the wrong angle

[Gunni]

That´s not really a problem in the long run, as long as you adjust the gearshifting mechanism.

[vanos]

So I'd better get looking for a 3.25 lsd from a E30 M3 then, seen one on ebay for £480 , whats a reasonable price for one

Anybody after a 3.64 LSD

Thanks for the help guys

[UweM3]

M3 track day guys will be after your 3.64 LSD. Maybe a swap??

[vanos]

M3 track day guys will be after your 3.64 LSD. Maybe a swap??

Thanks Uwe, is it best to post it in wanted and forsale for a swop ?

[beardymat]

Im running the five speed 3.0 box on a 3.2 with the standard 3.25 M3 diff and its pretty good although with my exhaust can get a little tiresome at motorway speeds. Keeping a 300bhp spec clutch in there makes sense to me.

[UweM3]

Im running the five speed 3.0 box on a 3.2 with the standard 3.25 M3 diff and its pretty good although with my exhaust can get a little tiresome at motorway speeds. Keeping a 300bhp spec clutch in there makes sense to me.

do you know top of your head the revs at 70mph or 80mph?

[beardymat]

Not exactly at the moment but im off out in it tomorrow on the motorway so ill take a note. somewhere between 3-4k at 70 is my best guess right now.

[UweM3]

Not exactly at the moment but im off out in it tomorrow on the motorway so ill take a note. somewhere between 3-4k at 70 is my best guess right now.

I only want to compare the revs at 70mph to the S14 I had fitted before to see if I run out of RPM in 5th gear.
Between 3 and 4k is a HUGE difference in speed. I would be grateful if you can narrow it down to 100-200 revs.
From memory i was running about 4.4k with the 3.73 diff with correct sized tyres but the S14 revved up to 8k and I don't want to rev that high with the S50B32 if I can avoid this (have a 3.25 diff fitted now BTW)

[DanThe]

This is with an M3 diff and 205/50/15 tyres, 1:1 5th gear



With S50 power id want a diff more in the region of 3:1 for a road car

[Jhonno]

4k is 90 with the 1:1 and 3.25.. 22.5mph/1000rpm iirc

[UweM3]

I was planning to run a 3:25 and maybe larger tyres if the gearing is too short. But mine is not a road car primarily.
Tyres I should use are 225/45/16 but I want to run 225/45/17 and maybe 255/40/17 rear
if I can make room in the wheel arches without too much cutting.

[Jhonno]

Mine was running 215/40/17 btw..

[beardymat]

Well I took note today and at a speedo indicated 70 it was doing 3100 revs but doing 70 by the sat nav saw it doing more like 3500. That's running 16" Evo wheels with standard size tyres.

[RoadHazard]

Stock E36 M3 is 3.15, isn't it? That's what I'm using.

[glenn]

Stock E36 M3 is 3.15, isn't it? That's what I'm using.

i'm not sure on standard 3.0's, but the evo's are 3.23:1

[DanThe]

Yep, 3.15 on a 3 litre, thats what im using now with my 6 speed box, gives this in 6th -

[RoadHazard]

Stock E36 M3 is 3.15, isn't it? That's what I'm using.

i'm not sure on standard 3.0's, but the evo's are 3.23:1

That makes sense because of the different gearing between the 5-speed and 6-speed.

[RoadHazard]

Yep, 3.15 on a 3 litre, thats what im using now with my 6 speed box, gives this in 6th -
...

Maybe I should try 2.93 with the 5-speed. That would give a similar result in the last gear, would it not?

[DanThe]

No, you would be approx 10mph slower @ 3000rpm, although it would be much better for driving on the road

[Mikey_Boy]

Sorry to be a bit off thread here, but are there really no issues with canting the E30 325 gearbox over another 15 degrees???

Considering an S50/M52 for mine with an E30 M3 gearbox with a direct drive top (which I already have fitted to the car), but a bit concerned about lubrication in the box??

Apologies again, but any pearls of wisdom are appreciated!

For what its worth - have a look at this:

http://www.catherineandken.co.uk/sti/tyres.html

This works out top speed in every gear and quite useful... For me as my car is used mainly for trackdays, having 4k on board at 80 is a small price to pay for the responsiveness on track, but of course I would do something else if it was a daily driver!

Cheers,
Mike

[Gunni]

It´s been done countless times in M50 conversions and I´ve never heard of issues.

[Mikey_Boy]

Thanks Gunni! Most helpful...!

Cheers,
Mike

[e21Jason]

I am running a s50 with a 265 getrag and a 3.9 diff but I tilted the engine and kept the box at the original angle as the s5O goes straight on the m20 mounts

Jason

[Jhonno]

I am running a s50 with a 265 getrag and a 3.9 diff but I tilted the engine and kept the box at the original angle as the s5O goes straight on the m20 mounts

Jason

Not sure I would fancy doing that.. I would be constantly shitting it about oil pickup! (Not saying it doesn't work, just I wouldn't do it..)

[e21Jason]

Twin pick up with modified sump pan with "wings"

[Jhonno]

Didn't think it would be a stock setup to be fair..

[Mikey_Boy]

+1

Definitely required and well executed I am sure!

Another option to consider darn it!

I bet an S50 with 265 box and 3.9 diff goes like stink.......!

[DanThe]

The gear ratios would be similar to using an E36 box and 3.25:1 diff