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MG MGB GT V8 Factory Originals Technical - 3.07 R&P Installation

The end is in sight for the Rover V8 conversion. One of the last tasks is installing a 3.07:1 ring and pinion. Upon disassembly, I find a .130" shim on the right side carrier bearing and a .125" shim on the left. Due to the size of the 3.07 pinion gear, which is about .400"+ larger in diameter than the 3.91, the ring gear needs to move .200"+ to the left. Seems to me that by moving the left side shim to the right, the carrier goes left .130". I still need .070"+. I suppose I could chuck the carrier in the lathe and take that amount off the mating surface of the carrier. That puts the ring gear in about the right position where I can check the contact pattern and back lash. It gives me the added benefit of losing the .003" run-out i have on the carrier (assuming my lathe runs true).

This looks to me like I loose .125" engagement of the right side axle and I'll need to lop the same .125" off of the left side axle to avoid and interference with the spider pinion.

Is this making sense to anyone or am I completely missing something here? Has anybody installed a 3.07 R&P and can tell me I'm on the right track or there's a much simpler way? I don't want to find out after I make a big pile of iron shavings.

Thanks in advance.

Steve Mc
Steve Mc

Steve, There is a spec for how much needed machined off of the standard 3.9 carrier. I'll see if I can find it for you. Where did you get the R&P?

Kelly
Kelly Combes

Thanks Kelly. If you could find that, it would help me out.

I bought the 3.07 R&P from Performance British in Ontario, Canada

http://www.performancebritish.com/
Steve Mc

I have the same set from Canada. I have not put mine in either, but you need to search on this forum. There are a couple of excellent threads with links, links to pictures, links to articles and all the questions you have will be answered.

Keep us up-to-date on your progress. You are on the right track.

If you can post pictures and notes along the way, I will personally use your experience when my turn comes.

There is a website mentioned in the thread that is for doing a ford 8" rear. It is nearly identical to the MGB in the way it goes together. Be sure and track it down and read it. It has some great ideas. Another guy honed a pinion bearing out (the id) so he could play with shims there. It was another great idea that isn't mentioned elsewhere.
Richard Morris

Steve, From what I can find .200 is the number to machine from the carrier. If you would like the authority on this subject, contact Clive Wheatley. I think that's where Performance British gets their stock. http://mgv8.homestead.com/ I think Clive supplies some of the best parts by far.

Kelly

Kelly Combes

Thanks for the info Kelly. The flange is only .390" from the mounting face to the bolt counterbores. Taking off.200" is a little more than half the thickness of the flange. I'll have to give this some thought.
Steve MC

Hi Steve I did the R&P on my MGB about 2 months ago and could not be happier. There is plenty of material to machine off. .390 is the flange thickness if you don't include the webbing. I machined .213" off mine with no issues. 0.200 would need MAJOR shim offset on the carrier. I would strongly recommend this conversion to any V8 powered MG. You will be pleased. I used a Clive Wheatley R&P.
M Mallaby

Steve, any progress on the installation?
Richard Morris

I cut 0.206" off the mating flange and I'm ready to try a test fit. Unfortunately, tomorrow I'm off on a business trip to India for a couple of weeks. I wanted to get the rear axle assembly done before the trip, but it looks like it'll have to wait until I'm back.
Steve Mc

This thread was discussed between 18/05/2007 and 28/05/2007

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