All you need to know about the M90

[ThunderCougarFalconBird]

Hi TB!

I just installed an M90 in my 1993 945T and I can't get the clutch to disengage. What's the best way to adjust the engagement point of the clutch?

In 1st gear with the rear end off the ground, the wheels spin the same even if the clutch pedal is fully depressed.

The clutch setup is off another TBer's 945T, with a flat flywheel, 850 clutch disc, and a pressure plate - though I couldn't say which one (I imagine it came with the flat flywheel). Since its last installation, the clutch disc was replaced (damaged in shipping) and the flywheel was refaced.

The clutch fork sticks out of the bellhousing perpendicular to the input shaft, and the pivot ball is already spaced on 4 washers. The slave cylinder rod is ~4 inches long. With the slave installed, the throwout bearing rests against the pressure plate. With the clutch pedal fully depressed, the slave moves the clutch fork ~1cm.

The hydraulic system was bled by pressing the pedal & bleeding the slave. I tried a reverse pressure bleed but it didn't go anywhere.

The master cylinder rod that attaches to the clutch pedal will spin, but that doesn't appear to adjust the rod length.

Where should I start adjusting? I can post a video of the clutch actuating if it would help with diagnosis!

Thank you!

[ZVOLV]

I would really really really bleed the clutch. I did a Mini Cooper transmission recently and it called for a special tool to compress the slave cylinder during bleeding and I was, like, " I don't need that ****!" And I was wrong. Couldn't get the cclutch to relase. Wouldn't even go into gear. I made a special tool, rebleed, and got it to work.


I doubt you could even smash a dog dish pressure plate against a flat wheel, but maybe.

Plate could also have bent or worn fingers. A fresh one should have been installed.


I forget exact spec for clutch pedal throw, but 1 cm may not be enough.

[Mule]

Just wondering if I can pick your collective brains?

So, I'm building a 240 with a T6 and whiteblock M90.

What would the best clutch set up be for 370-400bhp and 460ishNm?

850t5 240mm solid flywheel with shorter bolts.
850r clutch and a either a 850r pressure plate or Sachs 707 (is this a direct bolt on fit?).
Maintain the original external slave cylinder, fork and bearing or go to a concentric slave?

Is there a better set-up that doesn't cost the earth?

Any recommendations for UK suppliers?

I'm waiting to hear back from TTV.

Cheers for your help.

[Chris Wilson]

Originally Posted by Mule

Just wondering if I can pick your collective brains?

So, I'm building a 240 with a T6 and whiteblock M90.

What would the best clutch set up be for 370-400bhp and 460ishNm?

850t5 240mm solid flywheel with shorter bolts.
850r clutch and a either a 850r pressure plate or Sachs 707 (is this a direct bolt on fit?).
Maintain the original external slave cylinder, fork and bearing or go to a concentric slave?

Is there a better set-up that doesn't cost the earth?

Any recommendations for UK suppliers?

I'm waiting to hear back from TTV.

Cheers for your help.

Tilton or Quarter Master concentric release for sure, forks are like carburettors, history. Much better pedal feel, effort and reliability. Avoid ceramettalic clutch plates for a road driven car if you can find an organic plate and cover to handle the torque. Use a sprung centre plate. On a budget look at using a Saab or Ford concentric release, but you may spend the savings getting stuff made to fit them onto the bellhousing unless you have machining facilities FOC.

[Mule]

Originally Posted by Chris Wilson

Tilton or Quarter Master concentric release for sure, forks are like carburettors, history. Much better pedal feel, effort and reliability. Avoid ceramettalic clutch plates for a road driven car if you can find an organic plate and cover to handle the torque. Use a sprung centre plate. On a budget look at using a Saab or Ford concentric release, but you may spend the savings getting stuff made to fit them onto the bellhousing unless you have machining facilities FOC.

Cheers for the information.

Concentric master cylinder it is then. I'll have a look at the ones you recommend but maybe I can go Volvo 850?

Just thought I would clarify. I don't mind the prices of Volvo and Sachs new, so don't mind spending a few £££. I'm not in the position to spend on a custom clutch I don't think.

I think the 850R organic plate will be fine. It's more the pressure plate really and what's best.

[pujdeme_domu]

Hi guys, can somebody ensure me, the gearbox on picture

http://www.prestolholding.cz/admin/u...2fdd4b8013.jpg

is M90 whiteblock?

Thanks a lot

[V945]

Hi! Where on M90 I can find identification plate? I found number 6942485 on back side, it enough for detect modification M90?

[classicswede]

Originally Posted by pujdeme_domu

Hi guys, can somebody ensure me, the gearbox on picture

http://www.prestolholding.cz/admin/u...2fdd4b8013.jpg

is M90 whiteblock?

Thanks a lot

No it is not a whiteblock M90

[classicswede]

Originally Posted by V945

Hi! Where on M90 I can find identification plate? I found number 6942485 on back side, it enough for detect modification M90?

If still there it is a white label

[pujdeme_domu]

Originally Posted by classicswede

No it is not a whiteblock M90

Interesting is, that it fits B5234T3, the number is 1023650-8, I cannot find it anywhere, looks different than any other M90 marking

[themidnightgarage]

I am planning to put a M90 on my 1994 940 b200ft.
can i use the pressure plate from the m46 setup with a TDI clutch?
It has the same specs as far as i can see but im not sure.
Is there a difference between the m46 and the TDI pressure plate?
both are 228mm

[MadDog_945]

oh.. my.. god.. i opened it... this... is.. a mess :D

does anyone have plans of the m90? ;) This is the first time i opened something and fearing not being able to put it together again :D

[petiww]

Good pics, keep them coming!

I'm curious about the bearing sizes, i hope they are not some special 'only for m90 only' ones. Getting the preload right with new bearings is going to be pita though, more likely because I don't even know if the factory specs exist in any greenbook.

[MadDog_945]

Originally Posted by petiww

Good pics, keep them coming!

I'm curious about the bearing sizes, i hope they are not some special 'only for m90 only' ones. Getting the preload right with new bearings is going to be pita though, more likely because I don't even know if the factory specs exist in any greenbook.

thats the reason i opened that ****er up.. i want to know whether all the bearings are replaceable.. seems that koyo and skf is all over the place.. havent found a different manufacturer till now