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MG MGB GT V8 Factory Originals Technical - v8 tranny

Has Anyone had experience fitting a T-56 in a B behind a rover. I am building a twin turbo Rover that needs a tranny with a high torque rating. At least a 5 speed. Any ideas or insights?
Don Thorpe

Don, I don't recall a T56 ever being noted for a real high torque rating. Surely not over 250 lbs/ft?
Joe Ullman

Isn't the T56 the Borg-Warner 6-speed fitted to Corvettes and F-cars (GM)? If so, the engineers thought it would handle 350lb-ft of torque in cars weighing around 3400lbs. It's a rather large and heavy unit. Read the posts on the "B Rearend" thread for some valid comments on car weight and the effect on drivetrain components.

You don't really need a lot of gears in a light vehicle with a large engine, particularly if you are using forced induction instead of peaky, high RPM's to get your BHP. Consider a BW T5 5-speed - the V8 version has plenty of torque capacity, and is smaller, lighter and much cheaper than a T56.
Bob Wilson

The T56 is quite robust and can handle more torque that a B chassis could put to ground.

However, the T56 is quite large and heavy. I am not sure it will fit in a stock B tunnel.
Larry Embrey

I run a close ratio T-50, and find it suits the car perfectly with the stock axle and smaller diameter tires. (265/50-14, YMMV) 1st is a good launch gear, 2nd works well for level, easy starts, 5th takes the strain off the engine at highway speeds and gives a potential of 150 MPH at redline. That's around 3000rpm@75mph, which isn't much of a strain for such a short stroke engine, and the power is there instantly if you need it. The gear spreads are just right for the twisties, and with the top 4 gears in an H pattern I can't help thinking this transmission was designed with some sort of competition road racing in mind, where 1st is only used at the start, say something like a LeMans race for instance. Bob, if you or anyone else has any insight on the design of this transmission I'd like to hear it.
The only downside I know of is that 1st is a little awkward to get at, being under reverse on the left, and it is imperative that the 1st to reverse lockout be maintained in good working order. Plus, you have to learn the pattern.
Jim Blackwood

Can't add much, Jim. The T50 sounds like a good alternative. Probably cheaper than the T5 due to the unappealing cars it came in. Around 2-3 years ago the MG V8 Newsletter had a rather comprehensive article on the T-50 box. I don't know if back issues are available. In fact, it's been a while since I saw an issue in my mailbox - maybe someone knows if it's still going, and who to contact?

To see how another MGB V8 converter did it with a T50, have a look at Leon Zaks' site at http://www.zaks.com/mgb/
Bob Wilson

For high torque situations the t-5 is marginal. It can take around 300ft lbs.

A much better alternative is theTremec 3550 or TKO. These can handle 400 and 500 ft lbs respectively.

Info on the 3550 can be seen at.

www.footesparts.com

Larry
Larry Diede

Thanks Bob, I wrote that article, then in the next issue Kurt or somebody else provided the gear ratios for the three versions of the T-50 that are available. GM used the close ratio one behind the V-6's in Monzas, not sure where else. They wouldn't sell it behind a V-8, at east in the Oldsmobile, not absolutely certain about the Chevy. I know because I asked for one. It does fine with the 215. The wide ratio box turns the MG into a hole shot monster and gives a wild ride with a hot engine at WOT but is a little impractical for daily use. The third version has decent gear spreads but is direct drive in 5th. It'd do well with a 308.
Jim Blackwood

This thread was discussed between 13/10/2001 and 18/10/2001

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