In Defense of the Borg Warner T-50 Transmission
Not only is the T-50 a great transmission, you can use it to attract blonds. Can't do that with a Rover or T-5 box!

In Defense of the Borg Warner T-50 Transmission

as published in MG V-8 Newsletter, Volume VI Issue 2, August 1998

by: Jim Blackwood

Well, I guess its all in what you're looking for, over the past several issues I've read a number of letters criticizing the stalwart T-50, and I think it should get equal time. While it's true that some of the criticisms have a basis of sorts, I hope to explain those and show the transmission's virtues.

It has been said that first gear is useless. This is far from correct in all cases. To start with, there are two varieties of the transmission, distinguishable by the number of rings cut around the input shaft as I recall, and I have tried both in the MG. The preferred unit is the close ratio box which comes out of a V-8 Monza (Chevy of course). This makes for a very sporting and flexible powertrain as I will describe, but first, - ita concedo - were you to place the wide ratio box behind the V-8 there will be trouble. First gear becomes useless for anything short of a massive (but short) "Hole Shot", and it's too far between the other gears. It would end up being your "four speed with a "Granny Low". This wide ratio box is pretty common since it was used behind all four cylinder motors and in the S-10 trucks, whereas the performance oriented close ratio box, used in the lightweight Monza with V-8 power (265 and up) was sold primarily to enthusiasts. You have to wonder what they were thinking when they built this box, with its good ratios and a somewhat unusual shift pattern, but the answer has to be that Monzas were being used on road racing courses, and they wanted a suitable five speed. Since first gear was used for starting only (usually on Pit Row) the first-second shift was not critical, but the rest of the pattern had to be perfect. Ergo, the traditional "H" for the upper gears with first gear leading into the pattern... Putting reverse above first allowed a compact and fairly conventional layout of the gears and a very direct arrangement of shift rails for added strength and more reliable shifts. By the way, don't let the compact size of the case fool you, the gears and synchros are quite ample. (Ribbed thin-wall casting techniques were used to minimize size and weight.)


 Reader support is a critical component of BritishV8 funding:
Jim Blackwood

To prevent accidental shifts into reverse from first gear, an ingeniously simple solution in the form of a lockout tab was provided and it works exactly as it was intended to, provided it hasn't been damaged by external forces. Any shift to reverse or first is against a reasonably strong spring detent which only a real ham-fisted driver could miss, and once in first a shift directly to reverse is impossible since you must first release then re-compress the detent. A shift from first to second is only a push away, and then you're in the "H". Since no road course would require you to downshift to first, fighting the detent while - in extremis - would not be a problem, and it is easily negotiated under less stressful conditions such as in the Pits (or at a stop sign, or red light). Of course, the "H" pattern, as used in the upper gears is the beloved of all drivers, and cannot easily be beat for ease of use, simplicity, etc.

As I mentioned, this is a compact yet beefy transmission, with internal parts designed to take the abuse of an American V-8 in a lightweight car (by American standards) and designed for racing. As a result it uses needle bearings throughout, and lightweight, non-foaming, automatic transmission oil for a lubricant and coolant. As mentioned the gears are large, much larger than those seen in any of the boxes used in the MG's. The shift rails are also heavy and rigid, as is the shifter and the gates, and the synchros are massive by MG standards, having perhaps as much as three or four times the swept area. Here too, construction is of a typical, durable, effective and very reliable design identical in nearly all respects to the famous Muncie four-speed, with a hub, ring, two synchros, three blocker rings, and two large C-shaped keeper springs. They are very effective, and can withstand more abuse than nearly any driver can give them without blowing an elbow. HOWEVER, it must be remembered that you are dealing with a bit more mass than in a smaller transmission, and it takes just a bit longer to slow it down. The smallest bit of patience and planning in your shift points goes a very long way in alleviating the frustration of an impatient driver with perceived "hard shifts". The transmission does not shift hard. In fact it is a very easy shifting transmission if allowed to do its job. It will not, however, allow you to force it into grinding gears, and if you try it will abuse your tendons at least as badly as you abuse its synchros.


 Please support the sponsoring companies who make BritishV8 possible, including:

As far as usable ratios are concerned, again, what are you looking for? A sporting ride, or a luxo-sedan? I hear talk about axle ratios like 2.70's and such with an overdrive, and I would he astounded if not for the realization that these cars are not intended to ever be driven hard. I'll explain why. With the stock 3.90 axle, the T-50's overdrive fifth gear, and 24 inch diameter tires a 5,000 RPM redline brings me up to 150 MPH with extremely good acceleration in all gears. Cruising at 75 MPH, the motor is ticking over at three grand and punches through the 100 mark in nothing flat. The car comes off the line like a rocket and the 1-2 shift comes on the other side of the intersection right after the hole shot, just as it should be. Above first, all ratios are well placed, and the car is tractable and docile, yet powerful. On flat land or downhill starts (and mild uphills) starting in second is not a problem, making in-town driving no more of a chore than with any four-speed, using the conventional shift pattern. Use of the stock sized tires, something better than two inches larger in diameter, would drop the cruising RPM @ 75 to less than 2800, and increase the top speed at redline (6000) to over 162MPH.

I think we can all agree that this engine with a mild buildup is capable of supporting those numbers in this vehicle. The point is that you don't need to go any faster than that, but it sure is nice to have the acceleration. I don't honestly believe you'll gain very much fuel economy by dropping the engine speed another 500 or more RPM, as it's just loafing along anyway and with its short stroke runs very well at speed. If that's the goal, a better solution is fuel injection.

Enjoying this article? Our magazine is funded through the generous support of readers like you!
To contribute to our operating budget, please click here and follow the instructions.
(Suggested contribution is twenty bucks per year. Feel free to give more!)

Finally, in fitting the tranny to the MG, bellhousings are available from Phil Baker and from Dan LaGrou and a hydraulic throw-out bearing is a stock Chevy item. It is possible to use the stock crossmember with only minor alterations and a GM tranny mount. A little bending of the shifter will let it come through the floor in the right place, and after removal of the shifter extension the shaft can be ground, polished, painted, (chromed if you like) and a custom shifter fashioned for the top, allowing you to further individualize your car (or you can buy a knob). BTW, the pattern is very tight and precise when set up this way.

So why the bad rap? I think a few people have tried the wide ratio boxes, with the (now) obvious resulting disappointment. If you get the right one though, it's a whole new story. Best of' all, they're dirt cheap. I believe I bought one for $100 and the other for $80, and the good one was the cheaper one. So try adding this to your bag of tricks. You'll be glad you did.

Editor Kurt Schley added this note: The first transmission I had in my MG V-8 was a T-50 which I was unhappy with because of the unusable first gear and the unusual reverse gear shift position. I unconsciously shifted into reverse, thinking I was in first, several times and almost ended up as a hood ornament on the car behind me. Two years ago I switched to a T-5. After reading Jim's excellent article, I now realize that I had the wide ratio 6-cylinder box and that the reverse detent was not working on mine. To the T-50 transmission, I offer my apologies for all the bad things I said about you! Jim is also correct in stating that the T-50 is inexpensive. The last three I have seen at swap meets were all less than $150.



BORG-WARNER T50 FIVE-SPEED MANUAL TRANSMISSION

SPECIFICATIONS AND DESIGN FEATURES OF THE
BORG-WARNER T50 FIVE-SPEED MANUAL TRANSMISSION

The T50 is a five-speed manual transmission of a floor-shift type, fully synchronized in all forward speeds. It features a single rail shifter with shifting mechanisms totally enclosed.

It is end loaded, allowing use of an oval case for greater strength. It is designed to be interchangeable (with minimal adjustments) with current production manual transmissions of similar capacity.

Gear ratios (can be modified to customer requirements):

Vehicle Application: 1st2nd3rd4th5thREV
Overdrive top (smaller engines) 3.41 2.08 1.40 1.00 0.80 3.36
Overdrive top (larger engines) 3.10 1.89 1.27 1.00 0.84 3.06
Direct top 3.49 2.48 1.83 1.37 1.00 3.49

Efficiency:
1st gear 95.2%
2nd gear 96.5%
3rd gear 96.3%
4th gear 99.0%
5th gear 96.5%

Case and extension housing: Die-cast aluminum.

Weight: 65 pounds.

Gears: Helical throughout, including reverse; constant mesh reverse.

Operating temperature: -30F to 250F with current seals and the specified lubricant; to 275F with higher temperature seal material.

Synchronizer capacity: Consistent with a 205 pounds/feet passenger car application. Larger 1-2 synchronizer is available.

Oil retention: Dynamic oil seals are provided. Use of room temperature vulcanizing (RTV) static seal material eliminates oil leakage and provides metal-to-metal fit of mating parts.

Shift travel: Adaptable to customer requirements.

Other features: Live countershaft, blocker-type synchronizers, needle bearing support throughout and needle thrust bearings on the main shaft.



Notice:
    With digitization of this article in 2008, Jim Blackwood suggested the following additional comment:
    "I feel the torque limit of 205 ft/lbs should be strictly adhered to!"




Disclaimer: This page was researched and written by Jim Blackwood. Views expressed are those of the author, and are provided without warrantee or guarantee. Apply at your own risk.

British V8 Home:        Read the Magazine        Photo Gallery        Web Forum        Annual Meets        Contact Us        Site Map