Allright everyone, please weigh in on this one! You've never let me down!

Subject vehicle (that I will keep until they ban it or it gets hit):

1989 740 Turbo Sedan, M46 with Electric OD. 1031 rear with 3.54's. I have had a few of these M46's and the later ones are apparently the only good ones as early versions, including my original, failed miserably (needle bearing synchro failure). I currently have added 100k to this last one, and I don't know the total mileage.

Both Volvo mechanics I use and the research i have found says that I can bolt up an M47 (out of a 12/87 Volvo GLE) into my car (8/88 Turbo) as long as I use the tranny cross member, and driveshaft also. The local yard had a complete set for $300, so I pounced.

I am thinking about this because summer heat is coming, and though my OD has had the piston update, it has started to show signs of slippage again. 30 weight fixes that...for a while and at a fuel penalty,but to fix that again necessitates pulling the whole tranny down. I'd rather just toss in the M47 that sits in my garage at that point.

Thoughts? (thanks!)

 

M46 is more robust than the M47. That's specifically why Volvo only put the M47 behind n/a motors. Want a really hardy transmission? Do a T5 swap.

 

The M46 has a higher top gear than the M47. All the other ratios should be the same.

 

Thanks Swift and Titan. I was told about the strength of each. To be honest, I don't think the M46 was built strong enough either. I am aware of the T5 swap, but I am just looking for simple longevity. I will be in the market for another car soon ($4 gas!) but will keep the 740 too. I just want to know that I have a tranny that works, when I get to the point that the OD fails (again). I will be driving it easy.

When looking at the B230F and FT numbers, its hard to believe that i've had the trouble with the M46 that I did. Horsepower and torque are frankly....low. I've heard conflicting reports on the 47..."great" says one, "crap" says the other. But having a spare cheap tranny that will work is good. I'm not like "Howe and Howe" trying to destroy stuff.

Unless the Tranny fairy leaves a TG under my pillow, the M47 and grandma driving will be my backup plan. Thanks for the inputs...

 

I always feel compelled to defend the M46 these days. Most transmissions would be scrap after 150 or 200k. Without a rebuild by someone who a. has the Volvo green book and b. actually knows how to rebuild them from the ground up to factory specs the used trannys are bound to fail. My 94 B230T motor put over 300 hp to the rear wheels and nearly as much torque when in my 89 245. I was a hurry to finish the car so, as it was previously an auto, I threw in an AW70 w/ 125k on it. I knew the tranny would not hold up to a turbo and was right...it lasted 2 weeks. I then swapped in a used M46 over a weekend, again because I was in a hurry. Meanwhile, I had another M46 to start rebuilding laying on the bench. The used M46, w/ about 150k on it, in no time, lost the 1-2 shift fork pads, synchros and the od took a dump too. Since the transmission was thrashed, I continued to drive it occasionally until the other M46 was finished. As I've heard, and now know first hand, boost and o.d units do not mix. Never, ever, run WOT in od! LOL! After the new transmission was installed, I didn't have any issues at all. Of course, now it's sitting in a corner waiting to go into the GT. My point is, it's easy to forget how many miles are on these cars in most cases. Unless one has the time, patience and ability to bring major things like motors and transmissions back to new, problems will be inevitable. The best one can do is slowly stash extras for that rainy day. In 10 years or less, finding transmissions and rebuild-able motors at the jy will be but a fond memory.

 

Yesterday I went to the junkyard (in Utah) and saw an M46 in a car (I took the shifter ****). I hadn't seen one in a long time. It's an 87 so it's not quite as reliable as my post 88 M46, but it was tempting to get just to have one on hand in case I get a Volvo with an auto.

 

Swift, I hear you re the M46. Thought the earlier ones did have problems, I do feel I have a good one now. It purrs right along, despite the constant fluid-spec-changing by Volvo. I change it myself seasonally depending on what I need to do. I am sure this summer I will go back to ND 30 weight to get the OD to function correctly. You are correct that boost and OD's don't mix. If I stand on it and activate it, it simply will not shift until I let up in any situation, not that I make a habit of doing that. I just know it won't. The updated pistons were put in about 10 years ago, and they are starting to fail. Perhaps I need to see if VOlvo still sells those. But looking at the horsepower/torque figures from the boosted/non boosted engines, i must say its an unfortunate statement that the M47 can't handle the B230FT. But to get one complete, with every little bit and piece from to back top to bottom was just too good to pass up. And if/when it goes in the car, if I am reasonble with driving it, it should be okay. This 740 was repainted, and I put new trim etc on it, its clean as a whistle and looks great. I am soon in the market for another car, but will always keep this car around as a second, a mule, backup, and I use it to tow a small garden trailer too. The local yards here are crushing Volvos now, and I wonder if I just shouldn't BUY another 740 online to keep for doors, parts, etc.

 

I've had four cars over the years that used this transmission. Volvo always called for 10W30 motor oil and that's what I ran in all of them. This is thinner oil than normal gear lube and this is what is needed for the OD unit.

That being said, as the cars got more and more miles on them, I eventually replaced the oil in the transmissions with Amzoil 10W30 synthetic and always had good service from these gearboxes until the thrust bearings in the OD units gave out. But those bears have nothing to do with the oil being used.

 

I have a 90 240, when I got it 3 yrs ago reverse was out of it. So I hunted for m47 and a long story short. I went thru 4 transmission before I found one that did not wind, pop out of gear, or completely broke. My car is a NA with 200000 miles on it. I would spend money rebuilding a M46 before I would a M47. The M47's I went thru probably had alot of miles on them. I would take your 300 and find someone to rebuild your M46.