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MG MGB GT V8 Factory Originals Technical - The T5 Gearbox

I have just started researching this, but I understand that as an alternate to changing my rear axle ratio when I do my conversion, I can install a T5 gearbox.
What cars did this appear in? I have also read it bolts straight on to the Rover SD1 gearbox - is this so? Cost wise, which would be cheaper, the box or the new crown wheel and pinion? What about clutch/flywheel - Can I use the Rover one?
So many questions............ and all answers greatly appreciated.
Rob Whiting

Rob, the T5 is probably the best ratio-wise, but you'll find the cost rather high in Oz. The Toyota 5 speed box from a Supra or Celica is a cheaper option & you can still use your original diff. Dellows in Sydney do kits for Rover/MGs. The cost of a diff conversion (3.07/3.08-1) & a gearbox set up are very similar. HTHs Barrie E
Barrie Egerton

Rob,
The T5 designation is Borg Warner's term for a family of gearboxes not one specific box so choose with care.

Here they were fitted to Holden VN and later as standard.
The box itself is fairly agricultural and was a "built to a price" box. I have one fitted to my V6 Commodore so this is from personal experience. Generally fairly tough although somewhat baulky when cold which can be cured by using ATF in place of the usual gearbox oil.

The ratios are nicely spaced but the shifter lever itself can be a weak point. Mine has 470 000 kms on it and is original and still quiet (or as quiet as BW boxes get anyway!)

There was also a gearbox which is a development of the humble T5 called a Tremec also fitted to Holden and other makers as standard and capable of much higher torque capacity and is generally much more pleasant.

If you are looking to buy a box my suggestion would be go for the Toyota box as first choice. It is quieter, cheaper and more widely available.

One final point: There is one box which has an alloy casing and one which is steel casing but I cannot recall which is which.
Dellow Automotive should be able to better advise.

Cheers, Pete
Peter Thomas

Rob,
The T5 gearbox is not as good as the Supra 5 Speed.
The Supra box doesnt require the tunnel to be modified as much as a Rover SD1 box
As mentioned by Peter and Barrie, Dellow do a bellhousing kit to mate the supra 5 speed to a rover v8.
Also there are is an alloy case box and a steel one, i cant remember which one is better but i do know one is designed to handle maximum 300bhp , the other is more closer to 500 - 600bhp,
Lastly ive been told that dellow do not do a kit for the Supra 6 speed as they cant get enough supply of these g/box's

Hope this helps

Regards

Steve

Tremec T-5's are build stronger then a World Class T-5. Now the tranny's are rated by the amount of torque they can handle. I do not see why a supra five speed would be stronger I could see the six speed that comes in the Turbo version of the car to be stronger.
Dude

ALL T5s are now made by Tremec. BW sold the rights and the tooling to Tremec a few years ago. Tremec T5 transmissions are built to the same specs as the T5s built by BW. There are three classes of T5 - non-world class, world class, and heavy duty world class.

The "Tremec" 5-speed is not a T5, but it is a very heavy duty transmission, and it is a lot bigger than a T5 as well.

The "heavy duty" T5 is rated at 330ftlb, the "Tremec" is rated at 350 ftlbs. I don't recall offhand what the ratings are for the others.
Dan Masters

NOT ALL OF THOSE TRANS ARE THE SAME A T-5 IS NOT ALWAY HAVE THE SAME TQ RATING. BW DID NOT SELL UNTIL THE MID 90'S. SO ALL OF YOU PEOPLES JUST GOES TO HELL!
DE MONONICALS

Thanks Dan for all of that information. Hey other guy chill out man!!!!
Dude

From what I can recall,[Ichecked all this out when building 2xTR8s] the T5 will bolt up to the original Buick bellhousing ,not common in Oz, It does not go on to a Rover,Im running a Rover box at the moment,but willsoon be going to a Toyota5speed and a4.6litre Ipulled from a Rover VDP. The Rover /Triumph boxs dont handle grunt. The Celica box is steel, the supra alloy. The celica is the stronger.Have fun.
russell

This thread was discussed between 21/06/2003 and 09/07/2003

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