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MG MGB GT V8 Factory Originals Technical - Jeep rear end problem
|I am using a Dana 44 rear end from a DJ5 postal jeep on my V6 conversion. I had read on the BBS that the tube OD of this axle was same as the MGB. My Dana is 2 3/4 OD instead of the 2 1/2 of the B. The overall width is just right to replace the B differential however. The tube OD difference can be overcome with bigger U bolts from a Jeep set up and modified spring plates.|
My BIG problem is that in going to the MGB 4 bolt lug pattern, the bolt circle falls slightly within the ID of the 11 inch drums on the Dana 44. This means if I drill the 4 bolt pattern the lugs are only partialy surrounded by the cast iron drum.(50-75%??)
Anyone run into this and is there an alternate drum with a smaller ID I could use?? The ends of the axle shafts can be machined down to accept a smaller ID drum in fact the boss on the ends requires machining anyway to fit a "flat" profile as on the B. Thanks for any input.
|Thomas, Have a look at:|
This is a V6 website but there is a fair bit of discussion about the ins and outs of various Jeep rear ends being fitted to 'B's.
There are also a few paope there who specialise in conversions and so may be able to help.
Keep posting on the conversion...I am interested to know how it goes. Cheers, Pete, Sydney, Australia.
|Thanks to Reg Kennedy who got back to me with his solution to this one. He used the Jeep dana 44 in his V8 and solved the brake drum problem by going with a 76 Bronco drum which is 11x2 1/2 as well but with the smaller ID allowing for redrill of the bolt pattern once the boss on the axle is turned down. I will be trying this soon. A listing i have shows all 76-84 Bronco and F150's used this drum so it should be easy to get.|
|Super followup, Tom. Let us all know when you get the drum to verify all is good. Tom, did you have the "old" jeep holes welded up before redrilling or just leave them there?|
From my research it appears that both the DJ5 and CJ5 Narrow Track rear ends are the same width. I have not measured both so don't know for sure. Anyone Jeep experts out there?
|Well the Bronco drums, for whatever reason, are about 1/2 inch too wide so I am back to square one on this problem. i have a local parts guy seeing if there is any drum out there 11 inches dia. and 2 1/4 wide?? Gotta find one with a smaller center ID to be able to redrill.|
As far as welding on a brake drum? Don't do it!! They are cast iron and have to have some very specialized treatment to be welded and this includes a high temp preheat which would probably warp the casting. Just drill new holes for 4 bolt center.
|I onetime had a Dana 44 (on a 1972 Scout). I wanted to convert to later model drums that were, you guessed it, exactly 1/2 inch wider. (I had new drums from a 1978 on hand). To do this required the drum backing plates and brake innards from a later model (mid-70's up) Dana 44. My backing plates for the wider drums were from a mid 70's Scout. Yes, if you look at the two types of backing plates side by side the ones for the wider drums are a "deeper" forging. My conversion worked perfect.|
:::Thinking out loud::: Try an earlier, say 1972 or older Bronco drum, it may be narrower while still retaining the features you want.
BTW, I wanted to know about the holes in the axle hubs, not the drums themselves. I have heard of folks welding the hub holes shut, then redrilling, but I bet it is not necessary to weld the old holes shut. What did you do?
|Tom, haven't had the new holes drilled yet but it looks like there is enough space between existing holes to drill the 4 bolt pattern. One hole will be very close to the access hole used to bolt the axle retainer plate. Since the axle is steel it might be better to weld as you suggest as this would allow for a more ideal placement of the 4 bolt pattern. I will check out the older drums to see if they will work otherwise I guess it will require new backing plates and all the other pieces to go with it.|
|I'm not an expert but can't you just machine off the excess mat'l from the inboard braking surface edge to your desired lenght.|
|Jim, that possibility did come to mind but the drum then loses it's "seal" which is a ring fitting over the brake backing plate and any dirt, dust and water would easily enter the brake drum. The other issue may be the loss of the damping effect the heavy ring of material at this position provides. Might end up with a very nice harmonic every time the brakes are applied which would allow anyone for several blocks to hear the car coming?? Sort of like the ring you get from a wine glass???|
Not sure if they would work but 109" wheelbase LAnd Rovers use 11' diameter by 2-1/4" wide drums. The series 3 109's also used a Salisbury rear axle which is esssentially a Dana 60 built under license. I have put a Salisbury under the rear of our 67 series 2A 109 anc could check out the the drum pitch circle diameter for you. i know that it has 5 bolts and that it is a floating rear axle so the hole in the middle of the drum is rather large in diameter.
Best regards, David Walworth
|David, Thanks for your info. Any ID as large as 4 inches won't work since the MG is a 4 1/2 circle. The studs would break out into the ID of this drum. Any 11 by 2 inch drum with a smaller bolt circle would work. Not sure about a 2 1/4 wide drum??|
I just measured the diameter of the hub on our Land Rover. The hole in the drum is 4-1/2" diameter, I am afraid. It is, however, held on with three set screws in addition to the studs so you probably wouldn't have to worry about it coming loose. Good luck. If you don't mind going to a five bolt set up for the hub you could change the whole backing plate from a land Rover allowing you to use fully floating hubs for easy axle shaft changes when youtwist them off after hard acceleration. Probably bad for the unsprung weight, though. The idea of using ANY part of a Land Rover for a hot rod application is rather amusing, I must say.
Best regards, David Walworth
|Problem resolved!!!I went to the local boneyard and got some 11 inch backing plates off an old Ford E 100 van. Now using the even older (pre 76) drums with small center holes I will be able to have the axles and drums machined and drilled to the 4 bolt pattern.The Fords backing plates have more offset to the center of the car and allow for the wider drum and shoes. The Jeep brake set up and hardware is identical to the Ford except just narrower shoes. Not sure what size wheel cylinder the Fords used but using the Jeep one which is almost identical in diameter of the piston to the MGB should mean I won't need to mount a compensator?? It even looks like the one piece emergency brake cable from the jeep will be easy to adapt to the B's lever.|
Anyone trying this swap should get the Ford backing plates at the scrapyard and save themselves all the experimenting I have done.
This thread was discussed between 14/01/2002 and 02/02/2002
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