M52 with M20 flywheel - high clutch biting point

[jmc330i]

Sorting a few little niggles on a mates M52 conversion this week, one of which is a high biting point on the clutch - when releasing the pedal there is about 2/3 travel before getting to the biting point.

Its running an M40 gearbox, new master/slave and flexi hose (standard 318i), its got a lightened M20 flywheel and new clutch, but I think its a standard 325i release bearing.

I know the E21 323i bearing is slightly taller than the E30 325i bearing, but will this affect the height of the biting point?

Cheers

[jmc330i]

Bump

[maxfield]

Pretty much every car I've driven with a hydraulic clutch, the biting point is pretty much at top of the pedal.

[AndyZippy]

Yea with my M52, I'm running iS gearbox, brand new Sachs 325 clutch & release bearing, brand new master & slave cylinders and pipes, and lightened M20 flywheel - Biting point nearly half way up also!

[jmc330i]

So how come the E21 323i release bearing is recommended over the E30 325i bearing?

The biting point is too high on this IMO - my knee just touches the steering wheel when pulling away/changing gear and it makes it awkward to drive
Im not the tallest of people so the seat is quite far forward but I don't have the problem in my E30.

[jmc330i]

Drove the car to work today, the biting point is higher than I thought. It's pretty much at the end of the pedal travel and as I said above, my knee touches the steering wheel which really isn't great. I don't have this problem on my touring - the biting point is about halfway.

Someone has suggested trying an E36 slave cylinder, but I'm not sure that would help
So, does anyone know what difference the taller E21 release bearing would make?

[Jozi]

I have both the e21 and the 325 release bearing but the best I can do is put them side by side, I've no idea how they would differ with regards pedal travel.

[jmc330i]

Cool
I found the E21 323i bearing is 6mm 'taller' than the E30 bearing.

If I'm thinking about it right, the extra 6mm should compensate for the differing thickness between a standard M40 and lightened M20 flywheel - the thinner flywheel (with standard E30 bearing) would mean the slave cylinder would need to travel further and the biting point would be too high. It's also possible the clutch won't disengage properly, which makes sense as the gear change into 1st and reverse is really stiff, it really crunches into reverse!

[Jozi]

Ok so you've compared before. I've absolutely no idea on how these all work together. I'll be fitting the e21 bearing anyway to mine with the lightened m20 fly and in a m42 box.

[jmc330i]

It's only what I've read on the US forums, but I've not seen anybody actually explain why you need the E21 bearing.
As I said above, if I'm thinking about it right, it should make the difference.

I think I used the E21 bearing on my M44 conversion (lightened M20 flywheel, M40 gearbox), so it's basically the same as the M52 setup, but with differing release bearings.

I expect I'll be swapping the bearing on the M52 before long as it's the only thing I can think of that may cure the high biting point. It really isn't nice to drive at the moment

[nickso]

I used standard release bearing but welded two tabs onto the fork to raise the height. Couldn't be arsed ordering an E21 bearing or didn't like the price.....can't remember which.

[and1_e30]

where can you buy the e21 release bearing from I've gone onto euro and only found the clutch kits!

[Jozi]

You'll get it from the dealers, it's not cheap though! The e30 323 also used a metal bearing.

[BMW_E30vert]

Not too expensive here-

http://www.123spareparts.co.uk/search/c ... &hsn=&tsn=

[Jozi]

I think bmw was around 90euro or something.

[HairyScreech]

Its to compensate for the change in flywheel thickness from the dual mass m50/52 down to the thinner m20 one, the difference is about 9mm iirc, the e21 bearing is higher for the old style getrag 260 which had a 10mm deeper bell housing, which iirc is because of the flywheel mounted crank sensor.

I have just looked this one up as you can tell, same issues occur if you want to stick an e36 box onto an m20 to use compact/z3 diffs.

My solution to this is nickso inspired and involves a chunk welded onto the release fork, better to modify the non wear part than to have awkward to source wear parts.

As to why the biting point is high?
I wonder if it is due to the angle of the fork being wrong.
To take up the extra slack the slave would be too far out and the fork at an angle, I would be worried about popping the piston from the slave out when the clutch gets worn or about the bearing being pushed at a funny angle.

Slave wise, e30 slave with e30 master on an e30 box, no problems there.

[e30rapidic]

I have a US S50 with the zf transmission, running a lightweight single mass M20 flywheel and stock type 325i clutch masters stage 2 clutch kit. I originally had the stock 325i throwout bearing installed but my catch point was just off the floor. No good so I installed the taller 323 throwout bearing and it moved the catch point up to about 3 inches of the floor. I am running the e36 328i slave cylinder, I've been told to use the slave that goes with the transmission. However you may want to find a slave that has a shorter shaft on it.

A taller throwout bearing will not do you any good. I have a shorter throwout bearing that came with my clutch masters kit that I could not use. Maybe you can track one of those down? However I'm wondering if your throwout bearing is 90 degrees off? I've never seen a catch point that high.

I'll get a pic of all three throwout bearings for comparison soon, although you may have seen my comparison pic on R3V.

[HairyScreech]

Edit - ignore the below, were all idiots, only just read the OP properly to see he has an M40 gearbox.

What is the part number for the slave cylinder you have?? might be a slave with too small a diameter.





With regard to the above, your right, logic would say shorter but my thinking is that the slave has pumped up to take up the slack leaving the arm at an angle.
I am thinking the bearing is being pushed by the far left of the arm rather than the raised bit in the middle.

The angle of the arm may be causing the tricky pedal and if it has pumped out then it may give issues long term.

Slave cylinders are the same diameter internally on e36 and e30 so use the one that goes with the tranny, the mounting flange is in different places along the slave body.

[jmc330i]

Thanks guys Ive not been getting email notifications so didnt realise anyone had replied.

What is the part number for the slave cylinder you have?? might be a slave with too small a diameter.

I dont have the part numbers to hand, but its new standard E30 318i M40 master and slave, ordered from the reg of my 318i.

However I'm wondering if your throwout bearing is 90 degrees off? I've never seen a catch point that high.

I'll get a pic of all three throwout bearings for comparison soon, although you may have seen my comparison pic on R3V.

Ive not had the gearbox off yet, but what do you mean by 90 degrees off?

[HairyScreech]

According to Bmwfans the cylinder sizes are the same across pretty much all the e30/36 models so unlikely to be that.

[e30rapidic]

M3 uses a 22mm slave, non M's use a 20mm slave. Only difference is pedal feel, no difference in travel or catch point.