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Best Modified MGB V6 Rear-End

Posted by maggardmd 
maggardmd Avatar
Mark Maggard
Hope Hull, Alabama, USA   usa
Gentlemen,
It is time for me to invest in a modified rear end to handle torque of the 3400 V6.
I have destroyed 3 standard MGB rear ends.
I am running 3400L SFI V6 FWD engine bolted to a WC T5 with 2.95 first, 0.063 fifth.
Also using G-Force Clutch set-up. Have gotten weight down to 1950 lbs. Would like a light weight Limited slip with a variety of gears available.

I know this topic has been discussed over and over. I am sorry fo asking again for your knowledge. But i am unable to find satisfactory info in the search library.

I am asking for what has worked for you guys.
Thanks a Million,
Mark

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Jim Nichols
Sequim,WA, USA   usa
Mark, Do a Search on Ford Ranger 7.5. 83-92 offset rear end,use 2 short axles and narrow long tube. Can use Mustang rear discs. Comes out 53". If you eliminate C clips,cut 1/2" off axle ends and use small 9" ends end up 52". Trey on this site found a 3.08. 3.45 are common. You can use a factory limited slip,Tru-Trac gear type or 4x4 locker.
cgill Avatar
Chris Gill
Salmon Arm, British Columbia, Canada   can
1971 MG MGB GT
1979 MG MGB "BOPR V8 Conversion"
I have the Ford Range 7.5 in mine and it seems to work well. Jim is a wealth of information on how to modify it...well actually, he's a wealth of information for just about anything modified on a B!



My other obsession...photography!

http://www.flickr.com/photos/77646803@N00/

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BMC Avatar
BMC Gold Member
Brian Mc Cullough
Minneapolis, Minnesota, USA   usa
Mark,

I'm not sure if you are asking for best ratio or best type to convert.

Many things go into ratio including what your rev range is, what your driving style is and what the car is mostly used for- highway and top end on the race track might be a bit different from stop light to stop light with autocross mixed into the bunch.

Personally, my 3.4L with 2.95 1st and either a 0.63 or 0.68 5th can pull the 3.42:1 rear end gear ratio okay but i am going to 3.76 1st gear with a 0.72 overdrive.

I have built cars with 3.73:1 rear end gear ratio with the same T5 ratios that you and i both currently have.

I do not like driving cars with a 3.08:1 rear end and the same V8 T5 ratios that you and i have. Too high of 1st gear and all gears are too close for that total combo.

If I wanted to keep a 2.95 1st gear, I would leave my car with a little more power on takeoff with a 3.5-3.7 rear end ratio.

GM and Ford rear axles have good build qualities and parts availability.

-BMC.
BMC British Automobile   – Minneapolis, MN USA BMC British Automobile is a Restoration and Repair shop north of Minneapolis, Minnesota. Our time is spent solely on British vehicles and British Conversions. MG and Austin are our specialties.
bills Avatar
Bill Spohn
W. Vancouver, BC, Canada   can
In reply to # 2103024 by maggardmd I have destroyed 3 standard MGB rear ends.

How, Mark? Are you a drag racing start kind of guy? If not, it would surprise me that normal use would kill the fairly durable stock late model MGB diff.



Bill Spohn www.rhodo.citymax.com/carstuff.html
1958 MGA Twincam (race car), 1962 MGA Deluxe Coupe
1969 MGC roadster, 1957 Jamaican MGA
1965 Jensen CV8, 1971 Jensen Interceptor
1969 Lamborghini Islero S, 1988 Fiero GT turbo
2009 Pontiac Solstice GXP Coupe
West Vancouver BC
rficalora Avatar
Rob rficalora
Cypress, TX, USA   usa
1976 MG MGB V8 Conversion "MG MUTT"
I'm surprised you're breaking the rear axle too - especially if the car is 1950lbs. Plenty of folks run the stock rear end with V6's & even V8's. Typically folks swap them to get better gear ratios.

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NOHOME Avatar
Peter Plouf
London, Canada   can
1961 Austin-Healey Sprite Bugeye "Lil"
1967 MG MGB GT "Maggie (GT From Hell)"
Bit concerned if you are killing stock rear axles. The lighter options mentioned are not going to be much beefier in the bearing or gear department. Are you going to need a 9" ford to keep you in one piece?
maggardmd Avatar
Mark Maggard
Hope Hull, Alabama, USA   usa
In reply to # 2103363 by bills
In reply to # 2103024 by maggardmd I have destroyed 3 standard MGB rear ends.

How, Mark? Are you a drag racing start kind of guy? If not, it would surprise me that normal use would kill the fairly durable stock late model MGB diff.

I too was under the impession the stock 3.9 would hold up since it was original truck diff.
The weakest area of the diff is the "Spider Gears". When they explode the entire diff is trash!

It is true i like to "LAUNCH" of the line from time to time but there is so much wheel spin in 1st and 2nd that i don't see a lot of force beging applied to the diff because of "sliding friction vs static friction".

Well i guess i am wrong because i have created 3 great "boat anchors" with that thought.

maggardmd Avatar
Mark Maggard
Hope Hull, Alabama, USA   usa
In reply to # 2103280 by BMC Mark,

I'm not sure if you are asking for best ratio or best type to convert.
Personally, my 3.4L with 2.95 1st and either a 0.63 or 0.68 5th can pull the 3.42:1 rear end gear ratio okay but i am going to 3.76 1st gear with a 0.72 overdrive.

I have built cars with 3.73:1 rear end gear ratio with the same T5 ratios that you and i both currently have.

If I wanted to keep a 2.95 1st gear, I would leave my car with a little more power on takeoff with a 3.5-3.7 rear end ratio.

GM and Ford rear axles have good build qualities and parts availability.

-BMC.

Brian,
I have both 2.95 and 3.76 trannys like you. Why are you changing to the 3.76?
Also which GM or Ford diff would you recommend?
Are you still in the business of bulding custom rear-ends?

Mark
98chrysler Avatar
Jeremy Mulder
Dallas TX, USA   usa
I did a Ford 7.5 in my Midget. I used a '99 Mustang unit with a trac-loc and disc brakes. There is a lot of aftermarket support for the 7.5 and the 8". I had Mosier engineering make the axles which are supposed to be 20-30% stronger than stock. The Mustang guys I spoke with said the 7.5 is good for around 3-400 or so and the 8" up to 1000 with mods. I run the 2.73 set for fuel mileage.





My fuel injected MG Midget Project
Sorry folks, I do not battle the keyboard warriors, or feed the trolls!



Edited 1 time(s). Last edit at 07/01/2012 03:40PM by 98chrysler.

Jim Nichols
Sequim,WA, USA   usa
Mark, You can find a 90-92 Ranger 8.8 out of a 4.0 V6 pickup and do the same narrowing one side trick. Actually the 7.5 and 8.8 28 spline axles are the same. If you want to eliminate the spider gears use a 4X4 locker from Spartan,Aussie or Lock-Rite.
1744 Avatar
Bill Guzman
California, USA   usa
1973 MG MGB GT "Green GT"
1974 MG MGB "Punking"
Either 7.5 Ford or GM differential will work. If cut then go for the narrow 51" this will allowed the use of wider wheels and tires.
The red B has a 8" Ford 51" wide hub to hub and wider wheels and tires. The 8" Ford has drums brakes, great choice but harder to find.
The Orange B has a 7.5 Ford Mustang differential with 52" stock hub to hub.
Ford Ranger is the same, some come with the 3.73 final drive gear set with posi traction if they have the towing package.

Gear sets are inexpensive for either about $170.



It is our attitude that will determine the outcome
Classic Conversions Engineering MG Classic Conversions V6. Wilwood brake dealer.
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1744 Avatar
Bill Guzman
California, USA   usa
1973 MG MGB GT "Green GT"
1974 MG MGB "Punking"
This is a differential from a Camaro which is the same as the S-10 which it has less brackets to cut.
I choose this one due to the rear disc brakes 3.23 posi traction.

Cut axles from Moser $275, differential $125, cut the housing $250, bearing kit, seal kit including the axle bearings around $200.
No need to take chances if you are going to drive the B.



It is our attitude that will determine the outcome
Classic Conversions Engineering MG Classic Conversions V6. Wilwood brake dealer.
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1744 Avatar
Bill Guzman
California, USA   usa
1973 MG MGB GT "Green GT"
1974 MG MGB "Punking"
differences between the 8 inch Ford and the stock rear end.



It is our attitude that will determine the outcome
Classic Conversions Engineering MG Classic Conversions V6. Wilwood brake dealer.
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1744 Avatar
Bill Guzman
California, USA   usa
1973 MG MGB GT "Green GT"
1974 MG MGB "Punking"
This is the differential that went into my RD. It is a Ford Mustang 7.5 with Willwood rear brake kit.
BTW the rear brake kits are available at CCE for GM or Ford.



It is our attitude that will determine the outcome
Classic Conversions Engineering MG Classic Conversions V6. Wilwood brake dealer.
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tdecell Avatar
Trey Decell
Clinton, Mississippi, USA   usa
1974 MG MGB
1974 MG MGB GT
I've got a 7.5" Ford to put in the GT when it's done. The reason I went with a 3.08 is that I've got a V6 T5 trans, If I can come across a V8 trans, I can always swap gearsets. The Mustang disc brakes were a very easy swap, found the "how to" on a Ranger forum.



Blog-
www.tdecell.blogspot.com

rkassed Avatar
randy kassed
baton rouge, USA   usa
Hey Jim, I am interested in narrowing a 7.5 for my car also and what you mention seems to be the easiest way of going about it. When you say use the 9" end what do you mean? Also do you have a link to the thread that this info appeared on? Ive been trying to figure out what rear end to swap into my gt. thanks,
Randy
Jim Nichols
Sequim,WA, USA   usa
You can buy the small 9" axle tube ends from Strange,Moser and Currie. NOT the C clip eliminator which are prone to leak and meant for drag race only. The bearing and lock ring have to be bored(honed).020 and pressed on the axle. They replace the stock axle tube ends that would be cut off. The ends of the axles are cut off 1/2" to eliminate the C Clips and shorten. You can reuse your old spring pads or buy new early Jeep CJ 1 3/4" replacements. I don't know if Trey is doing the ends but hope he documents his work including the disc brake conversion. When I have time I hope to do two axles, one for the MGB and one for the Alpine.



Edited 1 time(s). Last edit at 06/27/2012 04:41PM by 260mgb.

jean gagne
st. andrews, new brunswick, Canada   can
Mark, you may want to consider the installation of a QWAIFE diff. You can fit any "B" gears that you want and you will never break it, never. It's warranted for life even if you race. I put 330 ft/lb through mine without problems. As for the axle shafts, we raced an E/P "B" for ten years and they never broke. I will grant you that when we retired the car the splines were a bit twisted.

You are unlikely to ever put the punishment that a race car serves on the differential and axles with a 3.4

Jean Gagne
St. Andrews, New Brunswick
rkassed Avatar
randy kassed
baton rouge, USA   usa
Jim, I am assuming you are talking about the bearing housings? like these... http://www.ebay.com/itm/9-Ford-Big-Ford-New-Style-3-8-Torino-Housing-Bearing-Ends-NEW-/370625777121?pt=Motors_Car_Truck_Parts_Accessories&hash=item564b048de1&vxp=mtr if so the ford 7.5 takes the same size bearings as the 9"?
Randy

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