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M90 Swap into low mileage 940T worth it?

M

migreig

New member
Joined
Sep 3, 2023
Hello all. I have a 1995 940T with just under 100,000k and while I love the car, I'm really a manual guy at heart. I'd like to swap a manual transmission into it, but want to keep it as close to an original setup as possible. This leaves me choosing between an M56, or an M90.

I have found an M90 in Europe (I'm Canadian) that comes with everything needed to do the swap, sans clutch and flywheel. My hesitation is that everything I read tells me that the M90 is not serviceable. I realize there's a lot of risk installing an unknown transmission into any car, but is it true that parts for these just don't exist? Sounds like if there's a problem, I'm SOL and hunting for another transmission. A task that will only get more difficult as time goes on.

The M90 swap is considerably less expensive than doing a CD009 or a Getrag, and is OEM standard, which is why I'm looking at this.

Thank you for your thoughts.
 
The M90 is a Getrag transmission, IIRC. Actually it is essentially the same as an M56 you described earlier, just turned 90° for use in a RWD application.

I have a '91 940 Turbo with an M90 and a very stock B230ft with a redblockpowered chip tune. Running something around 200 bhp, (as per benchracing math) with some kind of lightened flywheel and an 850R clutch, which are very available.

One thing to watch for is that the M90, like seemingly every other OE Volvo manual transmission has a somewhat weak third gear which can break if you power shift into third, miss a shift or are generally abusive to an old transmission. Mine has the third gear welded stop ring mod, and I would suggest you investigate doing the same.

Also make sure you're buying the right version of the M90, the M90H is meant for a whiteblock application.
 
NLRegina said:
For your purposes the M46 is better than the M47 like a dog turd is better than diarrhea. They have been known to break even under stock NA applications.
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I think I'd rather keep my aw71 than go to the M46. If I do swap, it's between a CD009 and an M90. That said, I'm favoring the latter as I haven't yet seen a single aftermarket trans setup that looks good in a 7/9 car.
 
migreig said:
I think I'd rather keep my aw71 than go to the M46. If I do swap, it's between a CD009 and an M90. That said, I'm favoring the latter as I haven't yet seen a single aftermarket trans setup that looks good in a 7/9 car.
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M90 is probably the best bet if you really really want an oem style manual imo but I wouldn't try to push a lot of power through it
 
migreig said:
Would 250hp be too much for an M90 in your opinion?
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I don't know to be honest, but I would question what your end goal is with increasing the power - 740s and 940s will never be sports cars unless they are very far from stock. How much of a difference will the extra power make for you versus the enjoyment of a manual transmission? Increasing the power will ultimately put more strain on the transmission no matter what. If you can find an oem example of an M90 or its derivation rated for 250 hp then it is probably safe. I think the 850s and such might have made around that much and used pretty much the same thing as an M90.
 
NLRegina said:
How much of a difference will the extra power make for you versus the enjoyment of a manual transmission?
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I've owned a lot of cars, it's over 50 now but I've lost track. I've found that 250hp is kind of the sweet spot where a car is just the right amount of spirited and fun. It's just a personal preference. If I had to choose between that and my current setup with a manual, I would take the manual trans every day of the week.
 
migreig said:
I've owned a lot of cars, it's over 50 now but I've lost track. I've found that 250hp is kind of the sweet spot where a car is just the right amount of spirited and fun. It's just a personal preference. If I had to choose between that and my current setup with a manual, I would take the manual trans every day of the week.
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https://turbobricks.com/index.php?threads/all-you-need-to-know-about-the-m90.94325/ I think this might answer many of your questions. You may very well be perfectly safe with 250hp on the M90
 
Just do it!!! Best upgrade that I have made and experienced so far....You DO Want to do the 3rd Gear Sychro Welding mod to further beef up the Stop Ring so a Missed Shift doesnt leave you stranded...I refreshened with New Input Shaft Bearing, New Seals, 3rd Gear Stop Ring Mod as well as New Hardware on the shift linkage, hydraulic pedal linkage(I bought Steel Clutch pedal) and new slave and master cylinders...You pretty much want to go over the Gearbox and associated pieces, including front prop shaft rubber and driveshaft rubber and mounts...I replaced u-joints as well while I was "In there"....Whatever it takes to make it a 1 Fingerprints Affair...
 
Familiarise yourself with the " Everything you Wanted to know about the M90 Articles", a Wealth of great info in there...
 
Its also been said that the M90 likes the Fine Wine of Manual Gearbox fluids; Part #'s in the M90 articles...Theres articles of replacement fluids but I personally chose to use what was recommended for it; no sense of totally refreshening and skimp out on the Oil that rows the gears...
 
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