Clicking M3 diff

[btccm3 1]

Hey guys

Thought Id throw this to the masses to get some feedback.

my 3.0e36 m3's diff started clicking quite badly the other day so iv parked her up and can't decide.

Should I fix it back to standard spec or take to it and fit a lower ratio set of splines for better in gear pull.

Also can somone please tell me what ratio the standard one is and if i wanted it to hit 240kph in 5th at 7G what ratio do you think i would need to cange it to.

And who would be the best shop to take the diff to to have this kind of work carried out???

[Gus 5]

hmm back to standard!

[*Glenn* 854]

Hey guys

Thought Id throw this to the masses to get some feedback.

my 3.0e36 m3's diff started clicking quite badly the other day so iv parked her up and can't decide.

Should I fix it back to standard spec or take to it and fit a lower ratio set of splines for better in gear pull.

Also can somone please tell me what ratio the standard one is and if i wanted it to hit 240kph in 5th at 7G what ratio do you think i would need to cange it to.

And who would be the best shop to take the diff to to have this kind of work carried out???

You sure it is the diff ?? Have you checked it properly?, It could be a driveshaft universal

[Greg111 13]

Could be the c.vs also?

[CamB 48]

if i wanted it to hit 240kph in 5th at 7G what ratio do you think i would need to cange it to.

Like the guys said, make sure its actually the diff. If it is, the LSD can be rebuilt.

If you want to change the ratio you need to figure which size diff you have - if its a 188 (medium case, I think the non-Evo M3s have this) then you can possibly pick a ratio from any medium case diff, but I expect you'd need to look to older cars (like e28 5 series or e30 325) to find the ratio and I've got no idea if they fit (being a Type 188 I don't see why not). There are heaps of ratios.

If its an Evo and a Type 210 diff then this is large case and you need to find the right ratio for that. Again, there are heaps of ratios but I couldn't guarantee what would and wouldn't fit.

For what its worth, I've got a small case e21 diff with an E30 small case ring and pinion and a 2002 small case rear cover, so there is certainly a degree of interchangeability. Mal Clark at Bygone Autos in Beachhaven changed the ratio in mine (and uprated the LSD).

For 240kph or so, assuming you have a 5spd and a 3.15 ratio, you'd be looking for about a 3.45 which gives about 245kph at 7000rpm. Since this means about 2850rpm for 100kph, are you sure this is what you want?

[btccm3 1]

im pretty sure its the diff as it only clicks once per revolution and iv already removed the drive shaft if you move the weels by hand it gives a definate click in the same place each revolution. are you 100% certan about the 3.45 doing 245 at 7G because the standard one is about 2900 - 2800 "give or take" at a 100 kph and its got about 255 at 7G at the moment in 5th.

do you think lowering the ratio a bit will make much difference is it worth it??

[BM WORLD 1284]

gearing calculator

[conrod 1]

The 3.0 M3 has a medium case (188) diff so plenty of ratios there. Sounds like you have broken a pinion tooth or three off, in which case you will need a new crownwheel and pinion, so may as well change the ratio if you want a bit better acceleration. Bear in mind fuel consumption will probably increase too.

Kayne Barrie @ Kayne Barrie motorsports is the best around for diff rebuilds on BMW's. He has all the tools, shims, clutch packs etc. and actually knows what he is doing! He is on the Nth Shore (Auckland)

0274 975 330

[CamB 48]

im pretty sure its the diff as it only clicks once per revolution and iv already removed the drive shaft if you move the weels by hand it gives a definate click in the same place each revolution. are you 100% certan about the 3.45 doing 245 at 7G because the standard one is about 2900 - 2800 "give or take" at a 100 kph and its got about 255 at 7G at the moment in 5th.

do you think lowering the ratio a bit will make much difference is it worth it??

Use the gearing calc and figure it out (5th should be 1:1, use a 3.46 and should be almost exactly 245kph with a 235/45R17).

To be honest, it sounds like you already have a 3.46, assuming a 5% speedo error.

Gear ratios here:

http://www.bmwmregistry.com/model_faq.php?id=14

What kind of gearbox does the 3.0-liter E36 M3 have?

All 3.0-liter E36 M3s regardless of engine type have a ZF Type C five-speed manual gearbox with the following ratios: 4.20 (1), 2.49 (2), 1.66 (3), 1.24 (4), 1.00 (5). This is mated to a limited slip differential (25%) with a 3.15:1 final drive.

[conrod 1]

I think the E36 M3 had a 3.25:1 diff.

[btccm3 1]

The 3.0 M3 has a medium case (188) diff so plenty of ratios there. Sounds like you have broken a pinion tooth or three off, in which case you will need a new crownwheel and pinion, so may as well change the ratio if you want a bit better acceleration. Bear in mind fuel consumption will probably increase too.

Kayne Barrie @ Kayne Barrie motorsports is the best around for diff rebuilds on BMW's. He has all the tools, shims, clutch packs etc. and actually knows what he is doing! He is on the Nth Shore (Auckland)

0274 975 330

gas is a non issue the m3's full time toy now its no daily driver.

Thanks for that ill give him a call im on the shore to so that makes life easy.

[CamB 48]

I think the E36 M3 had a 3.25:1 diff.

ETK says 3.15 medium case for a 3.0 M3 and 3.23 large case for a 3.2 M3.

[btccm3 1]

gearing calculator

hey thanks for that i now know i need about a 3.60 final drive as iv got 265 30 19s on my car that ratio will give me bang on what i want.

It would be a nice mix of both top end and pull

Edited July 17, 2008 by btccm3