• Hello Guest, welcome to the initial stages of our new platform!
    You can find some additional information about where we are in the process of migrating the board and setting up our new software here

    Thank you for being a part of our community!

All you need to know about the M90

I just measured the M90 front drive shaft half. from the flange where the flex disc is mounted (gearbox side) to the end of the splined end (center bearing area) is 744 mm (that is without flex disc). Maybe useful for the ppl who need a custom drive shaft. For the people who have such a piece laying around, please double check my measurement.
 
This is what I got. I will ask them for 1161745 instead of 1161645 and see what happens.
 
Last edited:
I added the technical info for both the 645 and 745 oils in the first post of the thread.
 
So M56's newer than '95 use something else, but it's ok for all years of M90?

I sometimes get the feeling volvo just makes this stuff up as they go along...
 
I sometimes get the feeling volvo just makes this stuff up as they go along...

yeah.... same here. first the ....645 oil was for M90/M56 etc, aka 95+. now ....645 is for everything until 1995 (M90, M46, M56 etc), and the .....745 is for everything after that date. I think someone is having a lot of fun somewhere in Sweden, changing oil specifications and other stuff "just because he can".
 
Hey Fred...a couple of things for the first post, perhaps...

Firstly, the reversing light switch is the same as for the M45, M46 and M47. No need to buy a brand new replacement at $40+ if it breaks. I found that out after I sheared the top off my M56 one, and spent the cash...and chopped the original plug off the loom... :-(

Secondly....no love for the Diesel M90 there ;)

cheers

James
 
So M56's newer than '95 use something else, but it's ok for all years of M90?

I sometimes get the feeling volvo just makes this stuff up as they go along...

yeah.... same here. first the ....645 oil was for M90/M56 etc, aka 95+. now ....645 is for everything until 1995 (M90, M46, M56 etc), and the .....745 is for everything after that date. I think someone is having a lot of fun somewhere in Sweden, changing oil specifications and other stuff "just because he can".
Both yes and no...

The 645 oil have been used for quite some time, and the first generation of M90 boxes were suppose to use that oil as well (with a manufacture date up to early/mid '96). When the second generation M90 boxes came out (and some other FWD boxes), the oil specification got changed.

The newer boxes should only use the 745 oil, and not the 645 oil.

Even though the 645 oil is for the older M90 boxes, the recommendation is to use the newer 745 oil even in the older gearboxes nowadays.
 
Hey Fred...a couple of things for the first post, perhaps...

Firstly, the reversing light switch is the same as for the M45, M46 and M47. No need to buy a brand new replacement at $40+ if it breaks. I found that out after I sheared the top off my M56 one, and spent the cash...and chopped the original plug off the loom... :-(
They don't offer any reverse light switches with original plugs for any gearbox here in Sweden now. They have been phased out. If you order a switch for an M46 or an M59 or whatever, you will still get the newest switch + a new plug and crimp connections.
 
And I said this before in another thread: Some M46 gearbox cross members are the same as the M90 one....
You can change that as well in your first post.
I will do that later today if I haven't already changed it a while ago. I will have to check.
 
The newer boxes should only use the 745 oil, and not the 645 oil.

Even though the 645 oil is for the older M90 boxes, the recommendation is to use the newer 745 oil even in the older gearboxes nowadays.

But, it says all years of M90 right on the bottle...
 
They don't offer any reverse light switches with original plugs for any gearbox here in Sweden now. They have been phased out. If you order a switch for an M46 or an M59 or whatever, you will still get the newest switch + a new plug and crimp connections.
Sure...but it means the pool of boxes you can pull an original switch from is much larger than you might otherwise think :)

I believe the switch grounds the feed from the lights. The ones on Ryan's 740 don't work either, so I may not be the best person to ask :rofl:

cheers

James
 
When installing the m90 in a 240, what kind of driveshaft (right word?) is best too use?
If i am not completely wrong you either have to shorten or lengthen it anyway(or make a spacer, which i want to avoid if possible), but what do you do with the mounting to the tunnel/floor(the one with the bearing inside the rubber thing)?
Make a new custom one?

Hopefully some of you understand what i mean, even though my writing isn't that good :)
 
I made a nice comparison picture of the difference between the Redblock M90 and the Diesel M90. The one on the left is for the redblock and the one on the right is a Diesel one.

dsc03560k.jpg


The most obvious way to recognize a Diesel one is that it's covered in inches of greasy crap and the red and whiteblock ones aren't :-P The Diesel one also has a different driveshaft and flange. It has, just like the whiteblock M90, a round 4 bolt flange instead of a triangular shaped flange with 3 bolt holes and doesn't use a rubber hardy disk but has a normal cardan. The flanges are interchangable though. I swapped them on my M90's as I don't have a redblock varient driveshaft but do have a diesel one. It all fits and is now mounted under my car.

This is a diesel driveshaft compared to the redblock M46 one:

dsc03522j.jpg
 
Last edited:
Back
Top