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All you need to know about the M90

  • Thread starter Thread starter frpe82
  • Start date Start date
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
 
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

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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.
 
petiww said:
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.
Click to expand...

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
 
Need to know more

So i got myself this M90 gearbox to install in my Amazon Combi B230 Turbo.
I am now running a M46, it is still holding up with the 227HP/373nm but i don't want to wait for d-day and prepair a stronger unit. Ofcorse more tunnel work and other mods will have to be done.

My guess was it was a M90L2.
Turing the input and count the revs in versus out, first and second gear confirmed it is indeed a L Type (L1 or L2).
Then doing the same on fifth gear to know if it is the L1 or the L2.
BUT... to my surprise it matches neither one of those :omg::omg::omg:

The L1 type has a 5 ratio of 0.81 to 1 and the L2 type 0.7 to one.

Mine has a 0.7525 to one ratio!

I googled about an hour to find other gearing types for the box but ALL showed the same, know as 0.81 and 0.7 5th gear.
I learned the internals *might* be interchangable between FWD M56/M66 and M90 boxes, so i looked that too (maybe someone switched the gearing on 5), but also for these boxes no 0.7525 or anything near that seem to exist.

I'm sure i did the correct measuring:
I first turned the input shaft until the out made a full turn. The in made about just 3/4 of a turn, just a tad more.
To find out how much exactly, i then turned until the out made 4 turns. The in made then 3 turns and a bigger tad.
So then i turned until the out made 16 turns, the in made 12 and about 14? extra.
Then i made 12 times 12 turns (on input) and found that the mark i made on input then almost made 1/2 turn extra to align the out on it's mark.
So i turned input again 12 times 12 turns (now total 24 x 12) and fount i needed to turn it once more 12 turns to get the input mark straight up (360 degrees) again.
Margin of error reading marks is very small now the input shaft turned 301 times, so the fault is devided by that! 2x(12x12), +12 (+1 the mark turned 360? extra)
while the out made 25 x 16 = 400 turns. 301/400 = 0.7525 gear ratio.

Now i suspect ALL documentation is WRONG about the L2 being 0.7 in 5
Did anyone alread did the math turning and counting, or did anyone already OPEN THE BOX AND COUNT THE TEETH ON FIFTH GEAR GEARS?

or do i just have an exotic and spooky M90 :oogle:
 
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Two days ago i bought myself another M90, this time a H1 type.
I did the test on all gears by turning and all are just like in the spec's.
Next step will be opening the L2 box, since no one seem te have done this to count the teeth on 5th...
I re-tested and re-calculated over and over, still come to 0.7525 / 1 or 270.9 degrees on the in for a full turn on out. :roll:
 
MadDog_945 said:
oh.. my.. god.. i opened it... this... is.. a mess :D
Click to expand...
Hi MadDog, did you put yours back together? :) and do you know what type it is?
I also opened my L2 to check 5th gear and i was right!,
drive gear is 46 teeth, driven gear is 30 teeht so 0.652174 ratio multiplied by the end ratio from secundary axle to outgoing axle (26 to 30 teeth) 1.153846 makes 0.7525084
SO ALL DOCUMENTATION IS WRONG!!!, or i have a special one :)

on this image of you the 5th is (for an L2) 30 teeth on the right axle top gear, and 46 teeth on the middle axle top gear (left axle is upside down in your pic but not important for 5th)
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I didn't get the outgoing axle out of the housing tail, did you press it or just hammer?
Is that middle part some removable bushing?
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Now i want to also open my H1 to check if i can swap first gear into the L2 :cool:
Anyone ever tried this?
 
mh.. sry long time ago.. i can remember i struggled hard on this one.. i had a guy helping me keeping the 2 shafts out of the way then just pull like a retard and it popped out..
 
Ok, i'll get it off somehow :)
Here is an image i found on the web i added some extra info and translate to another unspeakable langue :).
uPo8Yni.jpg

Also found that third gear is NOT 1.38 but 1.35, could be 1.38 if gear 16 had 42 teeth instead 41, i think someone miscount making the info, i count it at least 5 times :)
and Reverse is NOT 3.00 but 3.80, chequed also by turning, but who cares about reverse :-D

Here's the ratios i calculated on my L2 box:
1st: 3.9053254
2nd: 2.1978022
3th: 1.3516484
4th: 1
5th: 0.7525084
R: 3.4615385

Based on the number of teeth in the pic you can do the math.
After (if) i open my H1 box i'll post results here too.
cheers!

Edit nov. 24 2022: I edited the image, 1st gear is 13 teeth (not 12) thus R = 3.46 (1st gear was already correct)
 
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Does anyone have the pictures of the gearbox parts in the first post?

Just picked up another M90L2 and need some parts replaced.
Don't want to bother the dealer with all my questions about stuff they don't know.

Thanks.
 
I just finished my M90 install today and went for a successful test drive!

Resurfaced dogdish flywheel, Sachs/LUK diesel pressure plate and disc, 2 quarts of Syncromesh MTL.

I shimmed the clutch fork pivot pin with three washers. I bled the clutch several times by vacuum from below and I have a GOOD pedal feel.


Can somebody post pics of how the shifter assembly mounts to the body (two thru bolts/nuts?) and the order of the bushings/rubbers below the shift knob?
 
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Component 19 doesn't look quite like that in reality. The 'hook' bracket is wider, and is held in place by the same two bolts which hold in plate 33.

cheers

James
 
Hi, I need some advice and hope this is the place to ask. I'm sorry for digging up an old thread. I'm doing a manual conversion on my '97 960 3.0. Putting a M90 into it. I'm a bit unsure which flywheel I can use. The stock one, part no 9163902, seems to be very difficult to source. I've found a different one, part number 9176206 that is plentiful in the junkyards. It was used on several different cars, including the early S80s which have the same 3.0 engine as my 960. Would this be a good pick? I know most people prefer to swap in a single mass flywheel, but I'm not driving my car particilarly hard so I really don't see the point. I think this flywheel is for cars with an internal slave cylinder. I have no idea what that is, and I don't know if it would be an issue?

Also, I have a brand new Sachs clutch kit sitting on the shelf. It's the one for the 940/960 with the M90 transmission. Is there a chance I could use it with the S80 flywheel, 9176206? It's always nice to save a bit of money.
 
My M90 still produces a lot of noises in my 240. I have a dogdish and standard sachs diesel clutch. I tried different oils, helps a bit, but when it's warm there is still a lot of noise. in low gear it sometimes sounds like a tractor and the interior rattles in overrun. My car is a daily, so I want it as quiet as possible. The gear shifts super smooths, so i really want to keep it. Right now i'm thinking of putting a dual mass flywheel back in. Just to see what the difference really is. I have a known good dual mass flywheel. And i know of a few good ones lying around, when this one goes bust.

I was also thinking what do the fluid mounts do for NVH? The dual mass flywheel and the fluid mounts are the big engine differences between the 240 and the much quieter 940.
 
Timmermans said:
My M90 still produces a lot of noises in my 240. I have a dogdish and standard sachs diesel clutch. I tried different oils, helps a bit, but when it's warm there is still a lot of noise. in low gear it sometimes sounds like a tractor and the interior rattles in overrun. My car is a daily, so I want it as quiet as possible. The gear shifts super smooths, so i really want to keep it. Right now i'm thinking of putting a dual mass flywheel back in. Just to see what the difference really is. I have a known good dual mass flywheel. And i know of a few good ones lying around, when this one goes bust.

I was also thinking what do the fluid mounts do for NVH? The dual mass flywheel and the fluid mounts are the big engine differences between the 240 and the much quieter 940.
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A 3-axle gearbox is very noisy. The T56 in my '69 Camaro and the S6-37DZ in the 244 both clatter, particularly at idle and in coast down. The more you load them up, the quieter they get. I'm not saying you've gotta drive around at WOT but even at anything more than suburban speeds you should be ok.

There's a reason they come with a dual mass flywheel.
 
I have a stock dog dish flywheel and a diesel clutch disc and pressure plate. Mine doesn't make noise. The only noise I ever get is gear noise if I accelerate hard in first.

The last M90 I had made some noise, but I think it was a failing bearing.
Timmermans said:
My M90 still produces a lot of noises in my 240. I have a dogdish and standard sachs diesel clutch. I tried different oils, helps a bit, but when it's warm there is still a lot of noise. in low gear it sometimes sounds like a tractor and the interior rattles in overrun.
Click to expand...
 
Do you have a 240 or 940?
ZVOLV said:
I have a stock dog dish flywheel and a diesel clutch disc and pressure plate. Mine doesn't make noise. The only noise I ever get is gear noise if I accelerate hard in first.

The last M90 I had made some noise, but I think it was a failing bearing.
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Do you have a 240 or 940? I replaced the ball bearings when I fitted the gearbox. The roller bearrings feeled and looked okay, so no suspects there. So strange that some people don't have the noise. But then again, everybody experiences a car differently.

I never rode this car with the DMF. So I am just going to mount the dual mass flywheel and see what the difference is.
 
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