BritishV8 Forum

What is the best rear axle/disk brake combo for MGB  -  3.4L V6 with T5 tranny?

If you have the V8 T5 with 2.95 first and .63 OD it will work fine with the stock 3.91 rear. If you have the V6 T5 with 3.75 first and .72 OD get the 3.31 rear gears. Or a narrowed Ford, Chevy or Jeep rear axle. Scarebird has a disc kit for the MGB rear.

Jim,

thank you for your reply. I do have a V6 T5 combination. I am guessing you are referring to the tranny having a 3.75:1 ration for first gear?  I do not have a OD however the tranny is a five speed - I do not know the gear ratios for all the gears. I do believe you mean getting  a rear axle with a 3.31 ratio?  Also, I am installing fender flares and therefore would like to have wider rear tires. So the axle
( I like GM with disk brakes )  would need to have a certain length, right?
  I was trying to attach a pic but got the over 600Mb error) I still l don't know who to attach pictures I have no control over the Mb per picture.

Norbert, when folks refer to a V6 T5 or a V8 T5, they're referring to the original motor the T5 was designed to go behind.  I'm not sure how to best describe it, but there are actually a lot of different variations of T5.  Different versions will have different gear ratios, different size (diameter, length, & spline count) input shafts, different length tail sections, etc.  There's a good article here to learn more... http://www.britishv8.org/articles/borg-warner-t5-id-tags.htm

Also, on a 5 speed, 4th gear is typically 1:1 ratio and 5th is something smaller (.63, .72, etc).  That is your overdrive gear.

Jim, thank you for the clarification. I have a 2.8L V6 out of a Chevy S10, the engine has been bored out 030 and has a crankshaft from a 3.4L chevy engine. The T5, I believe came out of a Camarao, as did the EFI. The S10 have a carburetor setup. I have the correct  bellhousing with external clutch cylinder. I did use the article you're referring before I purchased the tranny.
Any recommendations regarding which rear axle I should be looking at?  Preferably with a disc brake ( alu caliper) set up, and the proper gear ratio. I am in the process of selecting the proper tires size based on the engine, transmission and axle ratio.

Norbert
It actually sound backwards but pick the tire size and wheel to fit your car then figure axle width and ratio but as mentioned above the T5 that came out of a 6 cylinder car usually have a different 1st and 5th gear ratio than the ones that came behind a V-8

I think that D&D fabrications (aluminium V8) still offer a 10 bolt rear axle with disk brake conversion that bolts straight into an MGB?

http://www.aluminumv8.com/Home/Gallery


I managed to modify my original MGB V8 rear axle for racing. I know this is NOT for road use. But I am proud of what I managed to fit inside the Factory MGB V8 axle case and still use the 43 year old ring and pinion gears on a Ford 9" spool.

As you should be, Perry!  

That was very slick, & so cool to see it work out.  Sadly, that is beyond many of us.

Norbert. The T5 you bought hopefully has an aluminum tag on the tail stock bolt on the upper left side with a number starting with 1352 and three numbers after that such as 142 etc. you can look up that number in the article referred to and that will give you all five gear ratios in the trans. then you can think  about rear ratios and tire size from there

I agree with Joe's advice.  That is the way the hotrod/streetrodders do it.  Get the tires & wheels (or, at least, figure that part out first) and go from there.