S50 + G260 in E30 Questions! Help pleeeease!

[durtyE30]

coding plug

What about the coding plug.....?

[lbreevesii]

might explain the tach

[durtyE30]

So what do I do with the coding plug? I'm a noob..

[bloodshot-e30]

check an make sure ur cam sensor isnt plugged into ur knock sensor.... lol ask me how i know.

[luckysnafu]

So what do I do with the coding plug? I'm a noob..

You need a late model 325i/325is coding plug from the cluster so that your car will rev to 7k instead of 5k.

[trackjunkie21]

You need a late model 325i/325is coding plug from the cluster so that your car will rev to 7k instead of 5k.

IT still revs the same way. It's just 2/3rds faster with the 4 cylinder plug.

[Mossman]

Wow I've had a rattling G260 behind an S52 for 2 years now, just thought it was signature getrag rattle. Now it's been to long to remember whether I replaced the pilot bearing, or whether I knew E36 and E30 pilot bearings were different back when I was doing the swap. I'm super super curious but not curious enough to drop the tranny. Hrmmmmmmmmmmmmmm

[AndrewK]

If it rattles while in neutral with the clutch pedal out, then it's probably the usual Getrag rattle. If it rattles with the clutch pedal pushed it, then could be throwout bearing or apparently (as the OP discovered) wrong pilot bearing.

[ForcedFirebird]

I didn't know you had a thread already.

Car is at my shop now and oh boy.

Pilot bearing was wrong, but not the issue. When the clutch is fully depressed the fork was hitting the pressure plate as if it didn't have any more travel (well limited by the PP back).

Took it apart and noticed when un-bolting the PP, the diaphragm spring starts to release. Started looking at the fork, it looks slightly bent, but the major problem I feel is that the shift fork pin is 1/4" closer to the bell housing on a ZF than it is on the g260.

[scottinAZ]

I didn't know you had a thread already.

Car is at my shop now and oh boy.

Pilot bearing was wrong, but not the issue. When the clutch is fully depressed the fork was hitting the pressure plate as if it didn't have any more travel (well limited by the PP back).

Took it apart and noticed when un-bolting the PP, the diaphragm spring starts to release. Started looking at the fork, it looks slightly bent, but the major problem I feel is that the shift fork pin is 1/4" closer to the bell housing on a ZF than it is on the g260.

IIRC the fork and the throwout bearing are the same between the G260 and the ZF transmissions. the difference is that the ZF was designed to fit over a dual mass fly and clutch, hence different geometry.

Having the correct pilot bearing will help as well

I had the opposite issue with my G260, in that the fork was bottoming out on the bellhousing, due to using a dual mass fly with a single mass transmission. no more room for the pressure plate to go, and was slipping as a result. two rub marks on the bellhousing where the slave pokes through verified this.

if I read the OP's first post correct, he is using an S50 fly and clutch, which should be dual mass. If this is the case, what transmission is he using (eta deep bellhousing, or I shallow bellhousing) he could be running into the same issue that got me. if there is no more room in the housing for the throwout to go, it will be rubbing on the fingers full time and can cause noise and other issues as well.

[ForcedFirebird]

Thanks Scott.

I have all of the Getrags here on the shelf and taken measurements on all of them. I have never had this problem on any of the swaps done except when we tried putting a 260 behind an m42.

The eta does not have a true dual mass FW, it's just bigger. I have an eta and have done several clutches/is/budget stroker swaps and people call them "dual mass" but they are actually just physically bigger whereas the g240/318 and the s/m50 have true dual mass FW's with independent rotating assy's - not one unit.

If I had the "is" g260 FW I would just bolt in the g260 stuff and be done with it, but like the 318/g260 swap, the "dual mass" part of the FW hits the oil pan/RMS cover by 1/4", but all I have is a pile of eta FW's and a 318 FW (which fits bit is too tiny for the s50). The eta FW has 1/4" extra meat on the back of it and weighs about 4-6lbs more than the "is" FW IIRC, been a while since I put them on a scale.

As far as the g260's being different, none that I can find. There is all 3 variations sitting here. The early shifter-only kind where there is no tabs sticking up to attach the late style shifter assy that needs the two holes drilled to hold the plate style (will also have the CPS holes drilled). Then I have a late/early that will fit all eta's and "is', it has the CPS holes, shifter plate holes and the tabs for a late shifter. Finally I have a late trans that has no CPS holes, but has the early and late shifter mounting bosses. Next to those I have a ZF and a g240.

When using a straight edge across the bell-housing (block surface) and measuring back to the pivot/fork pin there's a 1/4" difference on both the g240 and ZF from the g260. The ZF and g240 pins are aprox. 5" away from the front of the housing and the g260 is ~5 1/4", telling me that the TOB is already starting ~1/4" further back from the housing face than the g260 (the pin/pivot is physically longer, yet the housing measures the same). This would translate to more pedal travel to cover the same distance after system bleed.

So I decided to compare the forks. The g240 fork is flatter than the ZF/g260, with the ZF/g260 forks having the TOB closer to the housing face.

It all doesn't make sense to me.

[scottinAZ]

ok, what I ran into was this, I started with an M50 dual mass flywheel and clutch assy in a I g260, this clutch worked good, until the disc wore to the point that the fork was impinging on the housing. Replaced the M50 fly with a late Eta (6/87 IIRC) dual mass (yes the two halves have about 3/8" movement when pushed). This flywheel was FLAT on the back, so cleared the M50 oil pan nicely. New Eta/M50 clutch was installed in a late Eta (6/87) transmission. Both G260's had only provisions for the late aluminum shift carrier.
There was a running change at about 5/86 -7/86 that moved from the heavy single mass to the true dual mass flywheel. I had to do the research on this to make damn sure I had the right one. Major pain in the arse finding the right part, as they went from the change through the end of '87 MY only.

I also measured the distance on the slave side, and noted about 3/8" difference between the two transmissions in this area. this gave me the clearance for the clutch assy, but alas, the trans was shit, and so replaced with a ZF.

One thing I did note is that with the ZF and attendant slave, the pedal takeup and friction point is MUCH lower than the G260. say about 1 1/2 to 2 inches off the floor, whereas the G260 would be at half travel at friction point.

The main problem with the G260's is that there are so many goddamn variations of them that getting a COMPLETE setup is a pain in the ass. flywheel, clutch assy, TOB and the trans itself must all match to make it work.

My suggestion would be to see if the owner wants a ZF trans, and a lower numerical diff (2.93 is equivalent to a 3.73, given 5th gear ratios) and call it a day. fewer headaches and a stronger transmission to boot.

[ForcedFirebird]

Odd. My 10/86 eta had the single heavy single mass. I have no idea what trans this is but it does have the CPS locations indicating it is at least from an eta. My OEM trans has same dimensions but came with heavy single mass (bought the car with 70k miles). I gave up tonight and just got home. Will take more measurements tomorrow.

[scottinAZ]

6 7/8 is the measurement for the slave on the deep bellhousing. as I said before, there are so many variations its hard to get a cohesive idea on what the hell BMW was doing. Deep bellhousing, dual mass fly, stock throwout and fork should have you in good form.

One other thing to check would be the shape of the pressure plate, if there is significant variation on the bellhousing side as opposed to the Eta/M50 plate there could also be problems as well, although a simple check of fork part numbers, and a visual on the PP should be sufficient to see if there will be an issue....

[ForcedFirebird]

Took measurements of all the transmissions this morning. Forgot we also have a 97 s50 setup here, so took those measurements as well.

All the forks are the same. When assembled with the fork, TOB and slave (relaxed position) the TOB is ~1/4" closer to the diaphragm spring on the ZF's than it is on the g260's. This tells me there is at least 1/4" more for the slave to go on the G260 to meet the s50 PP - I say more since it is a lever and movement will be amplified.