Race Cars and Motorsports

Racers,

So, I have to drop the GM T5 transmission from my MG RV8 GT2 SCCA racer and repair/replace parts - in 3rd, 4th & 5th gears, the shift lever pops out of gear & there is much difficulty in engaging those gears.

Your opinions will be much appreciated on replacing parts in my GM T5 unit ..... on the subject of .....


..... did GM make a variety of T5 transmissions with "good, better, best" gearing - specifically, a GM T5 gear set that is a little better for road racing ? Since I must replace some defective parts in my GM T5, how can I improve the gearing even a little bit for racing ?

Any suggestions will be very much appreciated.

keep them on the track

phillip g

Phillip, I thought someone posted, in this forum, special after market(closer) ratios, but I seem powerless to find them. I pm'd Mike Perkins, as he might know. Temp gage on the trans ? Max temp was ? I would talk to "Royal Purple" tech., for a better lube. You can definately benefit from better/closer ratios and a superior lube. Good Luck, roverman.

The T5 was made by Borg Warner and sold to lots of car companies. When Borg Warner decided to stop making the T5, they sold its design rights to Tremec, and Tremec continued production. Tremec also offers uprated transmissions based on the original T5 design.

The original T5 came in first generation and second generation designs... the latter transmissions were called "World Class". You can read a bit about them here: Identifying Various T5 transmissions. The WC boxes have much better bearings.

Towards the end of Borg-Warner production, Ford Motorsport started offering a variant called "T5z" with even better bearings. I don't know if there's any real difference in the gears, or if there are other important differences inside the transmission. I've always heard that Ford installations got better designed shifters, but I don't really know how different they are. Aftermarket shifters are available too. After Borg-Warner sold the T5 business, Tremec continued producing the T5z for Ford Motorsport. Les Gonda is using a T5z in his MGB GT V8 racecar. It's a little inconvenient to install since the input shaft is longer, so Les has a milled aluminum spacer between bellhousing and gearbox. He believes it's entirely worth the effort.

Art, Curtis,

Thank you !

phillip g

Phil, sorry I haven't been by to see you lately. For your car I think the standard V8 T5 will be fine with a stock rebuild. So far the gear ratios have been working out fine, so no need to change them right now. I think we may gain more with a change back to the original modified stock shifter in place of the Hurst unit for a shorter throw and more comfortable gear selection for the driver. Worth a try and no expense there at all. We'll let Scott decide which he preferes. We may just have some wear on the shiff forks and need to adjust the stops on the Hurst shifter to fully engage the gears, not a problem with the original shifter as it doesn't have the stop bolts.

While that tranny is apart, this would be a good idea:

[www.5speeds.com]

I thought Phillip had mentioned, this is the OD. ratio ? IMHO, useless for road racing. OEM gearing charts list a .86 available, not optimum, but possibly passible ? Aftermarket ratios are out of budget ? Good Luck, roverman.

Phil I believe there are some things you would want to consider doing to your T5 should you decide to have it rebuilt. I'm not real sure what all the options are. I've heard carbon fiber scyncros mentioned, Carl's counter gear stabilizer, stronger bearings in cage. Perhaps someone on the site knows the details about what all you should consider doing. I'm thinking about changing my OD ratio gear set when I have mine gone through. Should I stay with electronic speedo? probably, just adapt the speedo.etc.

Let me know if you find a good tranny person up in your neck of the woods.
dave bash

Pehaps either Hanlon Trans. or D&D Performance can be of help. Both are reputable transmission suppliers and rebuilders of T-5's. i have done business with both and they
have tech depts also. The D&D is not the MG related business. I purchased the T-5Z from them. Hanlon sold me some parts for the old T-5 but I realized i needed a new one later. Hope this helps.

Racers,

Got the rebuilt T5 transmission back into the RV8 this past week - thanks to all the great help by Bill Davidson. I was hung up immediately at the 4th transmission bolt to the scattershield bellhousing. Bill found the way. And - reassembly was tougher than the disassembly .... thanks to the offensive hydraulic throw-out bearing. But thanks to Bill's steady perseverance I now have 5 forward gears.

Now onto the cold air induction system via the Spectre plenum and another dyno run might reveal a slight increase in HP.

I look forward to posting another dyno run on the "new/improved" Rover MG RV8 SCCA GT2 car soon.

kep them on the track,

phillip g