Which rear end for 400bhp MGB
I am worried that my latest engine modifications ( TA heads for my 4.8 rover ) will be too much for the stock axle and composite springs.
Planning on a 3 link with coilover shocks and mumford link. Have searched the net and have found conflicting views. My requirements are simple, it needs to be strong enough for say 450bhp (one day) but at the same time as light as possible. A well known rear end shop is suggesting that I need a 9inch to take that power. In pics the 9inch looks pretty big and would think that the rear seat/floor area will need panelling out which I don't mind as I would have to make room for the third link anyway. Is anyone using this axle in their MG? Do I really need it? I see a light weight housing and aluminium gear case is available to help keep the weight down. Mark |
mgb260 Jim Nichols Sequim,WA (2461 posts) Registered: 02/29/2008 08:29PM Main British Car: 1973 MGB roadster 260 Ford V8 |
Re: Which rear end for 400bhp MGB
Mark, You are in England, what's available over there? In America I would recommend either the Jeep Dana 44 (perfect width) or 90-92 Ford Ranger 8.8.(Needs 1 side shortened) On the Ford I would also replace the crush washer with solid spacer and eliminate C clips by shortening axles 1" and using small 9" ends. I don't know if they are available over there.
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DiDueColpi Fred Key West coast - Canada (1365 posts) Registered: 05/14/2010 03:06AM Main British Car: I really thought that I'd be an action figure by now! |
Re: Which rear end for 400bhp MGB
My vote for the 9" is a huge "no".
It's a gigantic, heavy, power consuming monster. It's only real claim to fame is that the neanderthals can't break it. If you put one in you can never say the word "handling" again. And say goodbye to 25 of your hard earned 450 hp. Most R&Ps 8" or bigger can handle roughly 400ftlbs of torque. (Torque is the yardstick that you need to use) In such a light car as the MG getting that much power to the ground is a real challenge. So an 8" is a realistic choice as long as a limited slip is installed. Having said that. I would probably lean towards a GM 8.5" rear end with a limited slip. Just to have a little margin for error (drag racing). Lots of choice (S10, Blazer, rear wheel sedans etc.) and lots of gear ratios available. Some came with disc brakes as well. Hope that helps. Cheers Fred |
Moderator Curtis Jacobson Portland Oregon (4576 posts) Registered: 10/12/2007 02:16AM Main British Car: 71 MGBGT, Buick 215 |
Re: Which rear end for 400bhp MGB
Are you willing and able to consider purpose built racing axles, like this one? [www.1speedway.com]
One can be seen in Phil's MG here. |
Re: Which rear end for 400bhp MGB
Thanks for your replies.
The only axle that I can think of over here is the Atlas which is ridiculously expensive and not a lot stronger than what I have now. I was originally planning on a Currie 8" with ally gear case but they advised against it as not strong enough. Love the racing axle but not much helpful info on their site, but have emailed them for more info. Maybe an 8.8 ford is the way to go but would prefer one from a mustang rather than an explorer as the tube size is smaller. Can only find one mustang axle for sale over here from an 84 car listed at £800 or $1300+. That's a lot for a worn out axle that needs chopping. Which are the best rear end companies. tried Moser but didn't get a reply, Currie enterprises want to sell me a 9 inch. Need to get this sorted Thanks mark Edited 1 time(s). Last edit at 01/17/2014 02:36PM by v8bloke. |
BlownMGB-V8 Jim Blackwood 9406 Gunpowder Rd., Florence, KY 41042 (6468 posts) Registered: 10/23/2007 12:59PM Main British Car: 1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS |
Re: Which rear end for 400bhp MGB
That 8.8 is also big and heavy. Several considerations:
-Strength is dependent on ring gear size. OEM MGB is 7-7/8", good for about 300hp/300tq max. -An 8-1/2" is good for 500/500. (You don't need 8.8 or 9") -As ring size goes up, weight and bulk increase exponentially. -A Salisbury type is always going to be heavier than a Banjo type. Alloy hogsheads are available for many Banjos. Banjo housings should be internally gusseted if used near their limits. The ideal solution? An internally gusseted 8-3/8 to 8-1/2" banjo axle with an alloy hogshead that used a shallow helix angle for greater efficiency. (Both the 8 and 9" ford axles use a deep helix angle and give up about 5% efficiency). But I don't know who made one. I don't doubt that it exists. There may be one in a European or Japanese car or truck. In metric that would be a 215 mm ring gear. In terms of a Salisbury axle, the Dana44 is probably the best choice, followed closely by the 10 bolt Chevy. Both had an 8-1/2" ring gear, both are very suitable in terms of strength, weight, bulk, availability and price plus availability and price of components, gear sets, and carriers (posi). Jim |
mgb260 Jim Nichols Sequim,WA (2461 posts) Registered: 02/29/2008 08:29PM Main British Car: 1973 MGB roadster 260 Ford V8 |
Re: Which rear end for 400bhp MGB
8 3/4" Mopar banjo is the best, but don't know if you can find one in England.
[www.moserengineering.com] [www.moparmusclemagazine.com] Edited 2 time(s). Last edit at 01/17/2014 04:24PM by mgb260. |
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mgb260 Jim Nichols Sequim,WA (2461 posts) Registered: 02/29/2008 08:29PM Main British Car: 1973 MGB roadster 260 Ford V8 |
Re: Which rear end for 400bhp MGB
Mark, After some research, the Land Rover series III and V8 up to 2003 have the Salisbury(Dana 44). The 90 has a 4 pinion clutch type posi like the American Power-Lock. Same inner parts as Jag. Axles are offset and you may luck out and only have to narrow one side with another short axle. You want the one with the 640mm short axle. You will have to redrill wheel lug pattern. 95-2002 have 3.54 gear ratios in coil sprung vehicles, I don't know what others are available but Jag and Dana 44 will swap with the right bolts or tubing spacers. Will have to look at the rear axles stateside for MGB's. May be different. Look for this rear cover shape:
Edited 5 time(s). Last edit at 01/18/2014 05:53AM by mgb260. |
Re: Which rear end for 400bhp MGB
Thankls all,
This is so difficult as I don't want to make a mistake in choosing which way to go. I like the look of the speedway rear end but they haven't replied to my email yet so hopefully will hear soon. Really would have liked the ford 8inch with ally gearcase but is it strong enough? The car is used mainly for track days so no hard launches and will never see the drag strip. The land rover rear end looks interesting but am concerned about parts inter changeabilty. Really need a 3.25:1 or higher ratio, Mark |
MGBV8 Carl Floyd Kingsport, TN (4511 posts) Registered: 10/23/2007 11:32PM Main British Car: 1979 MGB Buick 215 |
Re: Which rear end for 400bhp MGB
Hmm, wonder what that Land Rover rear weighs. Looks heavy. The 8 3/4 MOPAR is my fav for hodrods, but they are getting hard to find. Used to be plentiful & cheap.
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BlownMGB-V8 Jim Blackwood 9406 Gunpowder Rd., Florence, KY 41042 (6468 posts) Registered: 10/23/2007 12:59PM Main British Car: 1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS |
Re: Which rear end for 400bhp MGB
I wonder what the weight of the Mopar 8-3/4" is compared to the Dana44 or the Chevy 10 bolt. Neither will be as light as an 8" Ford of course but will be more efficient. The 8" has much stronger axles and spider gears than the MG axle but the ring and pinion is no better. Many have used them in higher horsepower applications but it is taking a chance, and in any event internal reinforcements of the hogshead flange would be absolutely essential in your application. Drag racers flogging the identically designed 9" found that flexing under hard launches changed the backlash causing greatly accelerated wear to the point where sometimes a set of gears would be shot after a dozen passes. That's 2-1/2 miles of hard use. Of course YMMV.
During the era that the MGB was manufactured, especially the Mark I and the MGA as well, it is reasonable to think that a larger sedan, perhaps some contemporary of Jaguar who was using the Dana hogshead but in the size you are looking for, might have used a larger version of the early MGB banjo axle. It is highly unlikely that any British car of the era used something like the 9" Ford, Dana 60 or 12" Chevy axle other than in a truck application but very reasonable to think they would use something a little heavier than the MGB used. What axle was in the Rover 3500 for instance? Wasn't that a Dana 44? Finding who manufactured the MGB Banjo axle would be a good first step. (Original application was a lorry? Or was that just the Salisbury?) Once you know who made it, finding what larger sizes they made and what vehicles they were used in should not be very difficult, especially if the company is still around. You could contact them directly. The design of that axle was really quite good, just what we are looking for in fact. An excellent balance of weight and strength and they are still very popular in racing even today. There is little doubt that the handling and ride of the car suffered with the upgrade to the Salisbury. But one of the heavier/somewhat more powerful cars of the 50's/60's is bound to have this axle. And there are still a few old timers around who will remember it. Go up a class or two in racing cars and doubtless you will run across it. Very likely it is still to be found on the historic racing circuit. Jim |
Re: Which rear end for 400bhp MGB
Tim
I have spent many years trying to get the handling as good as possible. I think the E type rear end will be way too heavy and im not convinced that the handling would suffer. this is how my car goes, [www.youtube.com] I want to keep the nimble handling characteristics. I have seen many Jag rear end conversions but never one that performs on track. Jim There are not many large powerful cars over here with a live axle. The SD1 isn't much stronger than the B axle looking at the shaft diameters. Cheers mark |
BlownMGB-V8 Jim Blackwood 9406 Gunpowder Rd., Florence, KY 41042 (6468 posts) Registered: 10/23/2007 12:59PM Main British Car: 1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS |
Re: Which rear end for 400bhp MGB
>Why not a Jag E-Type rear end.
Because unless you fully flare the fenders to an extra 3" per side you cannot get the uprights and knuckles outboard of the frame rails. If you do not get the knuckles outboard of the frame rails you either reduce suspension travel, increase ride height or both, and if you do that the car will not handle any better or even as well as with a solid axle, though the ride may be a little better in some ways. Plus, you add weight and though it is sprung weight, if you do not need it to counterbalance a heavier, more powerful engine up front it shifts the car's CG rearward, away from the ideal balance it originally has. Now, if you *do* flare the fenders out a full 3" per side, you can run up to 315 rubber on the rear and have up to a full 8" of rear suspension travel, the results being much better road holding with a more compliant suspension (MUCH better ride), a wider stance for flatter cornering, and more grip for acceleration. Plus you can accommodate another hundred pounds in the engine compartment and keep the weight balance in check. But you can't do that with the E-type suspension, it is too narrow. Use XJ-6. Jim |
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DiDueColpi Fred Key West coast - Canada (1365 posts) Registered: 05/14/2010 03:06AM Main British Car: I really thought that I'd be an action figure by now! |
Re: Which rear end for 400bhp MGB
I'm still "all in" for an 8" rear end.
Particularly for a track car. Unsprung weight is the concern here and the 8" is the lightest reasonable option. It isn't going to be indestructible like a larger diff. But it will handle better. And it will live a long happy life if maintained well. Have the axle tubes bent at the carrier end to give you some positive camber and away you go. Cheers Fred |
Re: Which rear end for 400bhp MGB
Yes I really like the look of the 8"! The drive shafts are 28 spline so stronger than the MG 21 spline shafts.
The weakness with the MG axle is the shafts but the diff itself holds up well. Is the 8" diff as strong as the MG axle? Just taken out my half shafts and yes there are signs that the splines are starting to twist. Its a shame that speedway didn't bother to get back to me. Mark |
BlownMGB-V8 Jim Blackwood 9406 Gunpowder Rd., Florence, KY 41042 (6468 posts) Registered: 10/23/2007 12:59PM Main British Car: 1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS |
Re: Which rear end for 400bhp MGB
The MG axle is weak in the shafts and the spider gears. About the same as the Ford 8" in the ring & pinion. But I personally have destroyed a stock MG R&P with a blown 215 and would be hesitant to push either it or the 8" much beyond 300/300.
Jim |
MGBV8 Carl Floyd Kingsport, TN (4511 posts) Registered: 10/23/2007 11:32PM Main British Car: 1979 MGB Buick 215 |
Re: Which rear end for 400bhp MGB
From allfordmustangs.com
Quote: From forums.mustangandfords.com Quote: Ford 8" & 9" spotter's info: [www.kevinstang.com] Edited 2 time(s). Last edit at 01/21/2014 03:58PM by MGBV8. |
ex-tyke Graham Creswick Chatham, Ontario, Canada (1165 posts) Registered: 10/25/2007 11:17AM Main British Car: 1976 MGB Ford 302 |
Re: Which rear end for 400bhp MGB
Thanks Carl......this reinforces the fact that my choice of the 8.8 Ford wasn't flawed.
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