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MG MGB GT V8 Factory Originals Technical - Brake update vs swap

Listers,
As stated in other threads I am in the middle of a rear axle swap, cooling system upgrade and other modifications.

While working on the rear end I noticed that the disk brakes were of similar size to the stock MGB disks up front. In fact they are a hair smaller and have a narrower pad surface. BUT they are thicker and have venting, plus they are the same or similar to Ford Mustang units so later upgrades to bigger disks and better calipers becomes an option. So I have a few questions.

Has anyone ever modified thier front brakes to something that is not a strick "bolt on"? This would require modifying the kingpin assembly to mount the calipers, but that may be it, and once done I am ready to get any upgrade mustang units I may want including larger disks and better calipers..

If I use front calipers that are the same size as the rear, or if I get matched calipers form a donor tbird will I still need a proportioning valve?

How hard is it to rebuild the MGB brake booster as I think mine might be leaking?

Should I just drop down the $$$ to get ventilated MGB brakes? I think cost will be about the same for both routes as wrecked Tbirds and mustangs are easy to find.
Larry Embrey

People have used four pot Wilwood calipers with Porsche 911 rotors, Peugeot rotors and 84-85 Nissan Z rotors. The Ford rotors would not stop as well as the stock MG and the only advantage would be the ability to make more frequent slow stops and you would be in greater need of a proportioning valve. The Nissan rotors have the MG PCD.
George B.

Gearoge,
I am curious why you would say the brakes would not stop as well as MGB stock units? The car they are designed to stop is probably 2x the weight of a MGB if not more, and it has to stop it within federal safety guidelines. Just does not make sense to me??
Larry Embrey

The diameter of the rotor has the greatest impact on stopping power, followed by swept area. You said that the Ford was deficient both if I read correctly.
George B.

Larry, I have Mustang brakes on the front of my B. They are from a mid 70's Mach I. Big beefy ventilated rotors and humongous calipers and pads that are dirt cheap to replace. Eventually I'll have discs on the rear too, but not quite yet. I've had the big brakes on for about 20 years now. The pads wear very well and brake fade is a thing of the past. I did get them to fade, but only one time and it was intentional, abusing the dickens out of them in the West Virginia mountains. They recovered immediately, and since I don't normally drive with one foot hard on the gas and the other hard on the brake while on a long steep downhill grade it hasn't recurred, no matter how hard I've driven it.

The swap required cutting off the hub flange and welding on a newly machined flange with the 5 lug pattern, and a mounting bracket milled from 5/8" plate with a couple of locating lugs welded on for the caliper mounts. I've seen a Dodge caliper that will bolt right up to the MGB spindle though, and the rotor can be re-drilled for the 4 bolt pattern, however, that left about 1/4" of the pad unused. Also, the Mustang hub will go on, same bearings and all, but the cotter will not go in.

In short, yes, it can and has been done.

Jim
Jim Blackwood

Jim how does the dodge or mustang front swap affect wheel offset/spacing?? I would be interested in finding out more info.. Just hinking that having matched front/rear calipers might lead to more balanced braking..

Larry Embrey

I would agree, but also recognize that the bore of the MC may need to be larger. American cars often have MC bores on the order of an inch or so in diameter. Just something to plan for in advance should a problem crop up.
The offset was something I was able to control as well by mounting a new flange, but I did the conversion back in '81 so some of the finer points are fuzzy. I do remember that the B flange is only flat on the back where the studs go. If you stay with 4 lug it's no problem, as the caliper is going to go where the rotor is anyway and bracket spacing has to put it there and it won't affect wheel track more than a half inch anyway. Seems like the Mustang offset was different by a significant amount, because I know I considered boring the race bores deeper to get the cotter pin in, But it may very well be that I simply decided re-flanging the hubs would be way cool. Maybe you can look at a Mach I hub at the parts store and compare if you want 5 lug.

The Dodge caliper was something Huffaker Racing was using, a mid to late 70's unit from a mid size car like a Duster or something. It bolted right up which was just too slick. However it was made for about a 1/2" larger rotor than the one they were using. They stayed with the 4 lug pattern I believe, so I'm not sure what rotor they used. The correct Dodge 5 lug rotor could of course be re-drilled for 5 lug Ford and backspacing between the rotor and caliper would need to be checked. Wouldn't want the pads popping out on you.

Jim
Jim Blackwood

Larry,

Exactly what do you mean by matching front and rear calipers? To get balanced braking, your front rotor/calipers must be considerably larger than the rear or you will require a proportioning valve. Earlier, I thought you were talking about using the Ford rear calipers on the front of your car. You also said that the Ford was much heavier than the MG, so why wouldn't it be better? The answer is that the rear brakes just don't do much of the stopping.
George B.

"While working on the rear end I noticed that the disk brakes were of similar size to the stock MGB disks up front. In fact they are a hair smaller and have a narrower pad surface. BUT they are thicker and have venting..."
...Larry: What type rear disc brake setup do you have? I looked on your web site but couldn't find any info on it...
anthony barnhill

This thread was discussed between 06/10/2002 and 14/10/2002

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