Which rear end for 400bhp MGB

[BlownMGB-V8]

Good to know. I would have had to cut the boxes to use the Ford IRS with the 8.8, but I guess that was because of the mounting lugs.

Jim

[kstevusa]

I had to notch the webbing on my 8.8 to clear the battery box.  possibly weakened it a "TAD" but do not get enough traction to cause a breakage  problem.  
SAFETY FASTER!

[v8bloke]

Latest thought is to fit a gripper LSD to the existing mg housing with provision for 28 spline shafts. Have new 9" ends welded to my tubes.
This would be the easiest option and I could also get good money for the quaife that I take out.
28 spline axles look a fair bit bigger than the Mg 21 splines.

Good plan?

[BlownMGB-V8]

That should just about take care of the weak shafts and spiders. It'll hold up for awhile that way but with 400 hp you might want to keep at lease one spare around for when you need, it as you almost certainly will.

Jim

[mgb260]

Mark, another weak point on the stock rear is the pinion crush sleeve. Should do a solid spacer and shims. I don't know what a Gripper is but I thought of a Aussie(Lokka) Locker for the 7.5  or 8"with the MGB cross pin. $250 with free shipping. Are you using the MGC ring gear?

http://lokka.com/site/home

http://fordmuscle.com/archives/2004/03/powertrax/index.php

[Scott Costanzo]

This is a great thread. I was seriously looking at a Ford 7.5" as a future upgrade but the 8.8" with 28 spline axles is probably the way to go. I was under the impression that the 8.8" was a really heavy rear end but it seems that the Explorer 8.8" with the 31 spline axles, and disc brakes weighs about 175 lbs. compared to about 160 lbs. for the stock axle. I would imagine that the 28 spline unit cut down for a B wouldn't be too far away from a stock rear end weight wise. According to info in the archives here the Dana 44 weighs about 190 lbs. I know this probably doesn't do much for Mark's situation across the pond but it was helpful for me.

[MG four six eight]

The Mopar 8 3/4" is plenty stout and with a Mopar Performance aluminum housing and Wilwood disc brakes I was able to get the weight down to around 160lbs if I remember correctly.

Pros,
Many came with limited slip.
Fairly easy to narrow and Moser has custom length axles.
Fairly light for how strong they are.
Aluminum housing saves about 9 pounds.
Still easy to get re-build parts for.


Cons,
Some of the taller gear ratios are getting harder to find new. (3.23 is just about ideal in an MGB with a V8)
The aluminum housing is expensive (about $1000)

Nuetral,
The aluminum housing requires removing the driver's side battery box on chrome bumper cars.

Bill

[ex-tyke]

My 8.8 started life in a '95 Mustang - I had to remove quite a bit of extraneous nodular housing bracketry that wasn't needed for the MG for weight savings......unfortunately I don't have a final weight.......Here's the final configuration.

[MGBV8]

Final configuration?!  You don't run rear brakes, Graham?  

Until I get ready to jump into the 300+HP pool, I think Jim Nichols' 7.5" Ford would do just fine for me.

[psmg]

Carl, if I remember correctly, you always said "brakes are highly over-rated". Or was it " Brakes? Who needs Brakes?" Anyway, hope you're staying warm.

[v8bloke]

Started chopping the MG today. Removing the rear of the boot floor and all the metalwork above the axle . This will make the whole job of fitting the suspension links much easier. Still planning on the Mumford linkage but will probably use a 4 link system as I am not keen on welding a a bracket to the cast diff. Will post pics. Also Collected new coilover shocks today.

Mark

[britcars]

{Final configuration?! You don't run rear brakes, Graham?  Until I get ready to jump into the 300+HP pool, I think Jim Nichols' 7.5" Ford would do just fine for me.}

Agreed.......putting together a 7.5" right now. The stock 3.9 has had a low growl for the past four years but got a bit worse last summer.  Time to change it out.  Planning to keep the stock drums though.

[rubbinisracin]

I'm running a Ford 8 inch ( http://www.britishv8.org/MG/IvanCollins.htm )  because Les Gonda did ( http://www.britishracecar.com/LesGonda-MG-MGBGTV8.htm ).  Mine doesn't have the upgraded third member but I did install new gears and a limited slip and upgraded half shafts.  No problems yet, but I really don't have a lot of really hard track miles on it yet either.  But I'd bet Les Gonda does.  

And here's how to make yours like Gonda's if you have a little extra cash.

http://www.currieenterprises.com/cestore/8inford.aspx

[74ls1tr6]

How about Ted Lathrops 8" with Auburn possi (sp) with 32 spline axles and spyder gears ($$$$)?.I upgraded to 32 spline axles. I figured as lite as these cars weigh. This is what Brenda's GT will have and I know her engine will put 400+ to the ground. My setup just came in today from Ted! Very well made and clean looking.

[Moderator]

Calvin, that's gorgeous!

[danmas]

How about Ted Lathrops 8" with Auburn possi (sp) with 32 spline axels and spyder gears ($$$$)?.

I have one of those. I'm only putting down less than 350HP, so I should be good to go.

That's good news, because you guys were starting to scare me.

[mowog1]

I also have a Lathrop Ford 8" with Auburn 3.27 posi.

[MGBV8]

32 spline? Typo?

[74ls1tr6]

Carl said:

Until I get ready to jump into the 300+HP pool, I think Jim Nichols' 7.5" Ford would do just fine for me.

In the Miata/Ls1,2,and 3 world they prefer to use the Ford 7.5" rear end. Again they said the car is light enough to use with the swaps. the 8" is to big for clearance issues in Miata applications. Just a thought!

Same issue with the R200's in the drifting cars, said to be good for 550lbs of torque. In that application it would be the stub axles are the week link.

Just my thoughts, a 3500lb car and up would be looking closer to the 8.8" or 9" ring and pinion, and the 400hp in front of them.

Of coarse I'm talking normal and spirited driving with no clutch dumping. We all can spin the tires with out cars fairly easy!

[74ls1tr6]

32 spline? Typo?

They are normally 28 spline axles. I was talking to Ted and asked him about 400+ torque with his 8", he said you can go with the 32 spline axles and gears. I said I'll go for the 32 splined axles and spider gears. I'm also running 3.54.1 because of 6 speed T56.

[MGBV8]

I think he meant 31 spline.  I wouldn't use the 28 spline, either.

[mgb260]

The 8" is right between the 7.5 and  8.8 in strength. Calvin is right on the lighter car being traction limited anyway. Carl's 300HP limit or use the 7.5 for 4 cyl,V6 or 215/3.5 V8. The 8" is perfect for 300 to a little over 400HP. Actually Torque is a better number. That is what breaks things The 8.8 if built right, is right up there with the Dana 44 and 9", should be good for 500HP. The 31 spline axles are larger diameter and stronger. For racing, I think the Dana 44  or 8.8 would be the answer.

[74ls1tr6]

You at right Carl 31 spline!

[TXS67BGT]

just to add another option in the mix, and Jim Nichols I hope you chime in here, I bought a rearend from a wrecked 98 Camaro Z28, 3.43:1 with disks, Eaton posi, seemed at the time to be just what I wanted, during the rebuild bought new bearings, clutch disks everything I thought I would need. the bearings for a 7.5 did not fit, after digging around with the local Chevy Parts guy he showed me that it was a 7 5/8, only two ratios available, ordered the bearings for that and they fit. Local (Kent Washington at the time) rearend specialist did the cutting and welding said he had seen only one other 7 5/8, said the tube walls were thicker than the standard 7.5. now all this is from memory, thought at the time I was rather lucky to run across it, hope all I have said is correct, do know it had Aussie aluminum calipers. The shop I bought it from had it in a car they had been drag racing with, behind a 415HP LS1 and it held up fine behind an 4L60E trans.

[MGBV8]

How many bolts holding on the cover, 9 or 10? Sounds like it could be an Australian 9 Bolt.

They are actually pretty stout. A friend of mine had a Third Gen Camaro with one. It survived his Paxton centrifugal blower equipped engine & a 5 speed.

Great info:

http://www.thirdgen.org/techboard/faq-board/239666-everything-i-know-about.html