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MG MGB GT V8 Factory Originals Technical - Hello Ralph, Germany! More axle help!

Hi Ralph,

You posted this to me a few weeks ago, very useful and hard to get information -

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Posted 04 March 2006 at 20:22:07 UK time
Ralph, Germany

Hi Liam,

here are the part numbers for the Sailsbury axle:
3.070 is BTB900 on diff cage BTB840
3.307 is BTB841 on BTB840
3.700 is BTB1244 on BTB866
3.907 is BTB856 on BTB866

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I opened the new (old) C axle up, which I think is suposed to be a 3.3, and the number on the ring gear is :

MOWOG BTB842 13 43 (it's a bit worn)

Can you tell me what that means, or where I can find out? It is not listed in your information above.

Liam
Liam

Liam,

There appears to be a typo in the list, but the 13 and the 43 is the way they express the ratio. That is there are 13 teeth to 43 teeth and if you divide 43 by 13 you get how many revolutions the drive shaft makes per turn of the axle, which is .3076923076923076923076923076923 or rounded to 3.3
George Champion

Way to go, George!

My calculator only goes to 3.307692307 :)
Carl Floyd

Thanks George, that is a relief.

The axle seems to be in decent condition, external crud and rust but nothing too serious. Internallly, no chipped teeth or slop in the gear mechanism. I can still see the concave washers under the planet (?) wheels.

Will need to change the hubs over, these hubs have 5 wheel studs. Don't know why that is.

Liam.
Liam

Liam,

You’re welcome and congratulations on finding a good one. BTW you could have counted the teeth if the stampings were too worn. I also remember reading the ratio was stamped somewhere on the axle so it wouldn’t be necessary to open it up. Verifying the internal parts are sound makes opening it worth it.

Carl,

Cheater! Why use a calculator when a pencil and paper could give the answer? OK, I’ll fess up. I used the calculator build into Windows and copied and pasted the number rather than bothering to copy it.
George Champion

Hi Liam,

sorry for beeing that late, but George has allredy perfectly explaned the facts.
The difference with the hubs is due to the different wheels used on the C. The drums are also a little smaler but wider. It is an easy swap to put on the bits from your original B axle and everything bolts into place easyly.
Doing this conversion, you should use the occation to fit new seals at the hubs and check the axle breather (smal plastic bit on one of the shafts) for beeing not blocked by grid, paint, taar...

Ralph
Ralph

Thanks everyone for the very useful info - I have been amazing friends and family by taking them into the garage and explaining how the numbering system on the ring gear works!
Liam

Hi Liam
Well done on finding a good axle. After you have converted the hubs and drums to 4 stud, do you fancy selling me your 5 stud hubs and drums? Been looking for some for a little while.
Ta!
Nick Bentley

Hi Nick,

Happy to try to help but I'm not 100% sure what bits I can swap, obviously the stud hubs - but are the drums etc not the same as the MGB? Might save a bit on postage to Shetland!

Liam


Liam

Hi Liam
The drums slip over the wheelstuds (5 on an mgc hub) and so have 5 holes in them instead of 4. Give me an email with a contact number so we can have a chat.
Ta!
Nick Bentley

Liam... I just completed this swap today from B 3.9 to MGC 3.3, quite simple. Just swapped the hubs, retained the B backing plates and used the B drums, the C drums wont fit. I also replaced the axle seals, pinion seal and swapped in the pinion flange from the B. This eliminated modifying my drive shaft. Only issue was that stock tires will rub since C housing is narrower.
Very pleased with the difference.

Morgan
Morgan Sellgren

Will do, Nick. I might try and get then off tonight, see if I can get some photos.

Morgan - what was the wheel clearance issue and did you resolve it just by tire choice? I thought the axles were externally identical - are you talking about a wire wheel C axle?

I have a standard non-wire C axle and will be using standard B rostyles. I had hoped it would be OK clearance wise.

Also, was it a simple job to swap the propshaft flange over? - in the manual it talks about shims and measuring float.

Liam
Liam

Hi Morgan,

I just read your other post, I'm glad you got it resolved and it answered my question so makes most of my previous post redundant!

But would still appreciate your experiences with the propshaft flange change over.

Cheers, Liam.
Liam

This thread was discussed between 25/04/2006 and 01/05/2006

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