Hello,

Does anyone know the rear end ratio of the 16 valve(B234F) equipped 740's? I heard that it was different than the turbo and normally aspirated cars due to the unique torque curve of the engine. Since I am going to swap a B230T into the car is this a good or bad thing? From what I know about the B234F all of the horsepower and torque was in the top end, so I would imagine the rearend ratio being lower (Numerically higher) to compensate. I think this would be great in a turbo car for off the line power. Also, what are the ratios of the manual trannies (M46?) that came in the 700 series? I'd like to run the whole thing through a gear calculator and see what the cruise rpm would be.

Thanks,

Matthew C. Hall

700 Series Gear Ratios:

Trans___ M46 __ M47 __ AW70/71 _ AW72(B234F only)

1st ___ 4.03 _ 4.03 _____ 2.45 _ 2.83

2nd ___ 2.16 _ 2.16 _____ 1.45 _ 1.49

3rd ___ 1.37 _ 1.37 _____ 1.00 _ 1.00

4th ___ 1.00 _ 1.00 _____ 0.69 _ 0.73

5th __________ 0.82 _______ w/Lockup

OD ____ 0.78 ________________________

Rev ___ 3.68 _ 3.68 _____ 2.21 _ 2.70

Axle __ 3.73 _ 3.54 _____ 3.73 _ 4.10

or ___ 3.54 _ 3.31 _____ 4.10

trans/rear axle combo depends on year/model/engine

[source Volvo + Haynes]

I wouldn't worry about it at all. I recently swapped trannys from a M46 to a AW71 (B230FT) and my car has a 3.56 rear end ratio whereas the doner auto trans car had a 3.73 rear end ratio. I can't notice a problem with accel due to the slight ratio difference but the auto trans gives me lower RPMs at high speeds (like only 3000rpms at 90mph whereas it was closer to 3500 with the M46).

Swapping a B230FT into a car that originally had a B234F won't be an easy or inexpensive task otherwise. I wouldn't even consider it myself. You'ld be better off finding a used B234F, installing that and either leave it like that or sell the car if you don't like that engine.

According to Paul Grimshaw's book "The Volvo Performance Handbook" the AW72 transmission on 700's and 900's with the B234 16-valve motor has ratios of 2.83, 1.49, 1.00, and 0.73 (OD) driving a 4.10 ratio rear. The rear is a Dana 30 used in lots of Chrysler Corp cars (Mopar) and Jeeps. There are lots of aftermarket gear sets available as well as limited slip and various locker options as well. Check out a copy of Mopar Action magazine for ads and ideas. The AW72L on my '91 940 has a lock-up torque converter - don't know about the earlier 700s. If you use the AW72 with your turbo be aware that the stall speed is higher than the AW71 2450 vs 2000. Would help drag racing but might not be as drivable around town.

Good luck with your swap.