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MG MGB GT V8 Factory Originals Technical - V-8 Calipers
|I'm attempting to run v-8 rotors on my B race car. The calipers I have slotted to accept a rotor thickness of about .48" max, while the V-8 rotors are .50" thick.|
I understand in the UK Austing Princess(?) caliper halves are slotted to accept the thicker disk.
Any advice on how to accomplish this without importing the Princess calipers? I'll try to import those calipers if there is no other option
|Okay, i've read further and it's Triumph P2500 caliper halves, not Austin Princess, and the halves are bolted to the MGB outer to make an MGBGTV8 caliper.|
Since I'm required to run MGB calipers, and this was an available option, (No 4-piston or aftermarket calipers), it's the direction I think I need to head.
Grateful for any comments or suggestions
|Greg, the Austin Princess / Ambassador 4-pot caliper is a good substitute for the MGB with V8 discs. However, they are not that easy to find these days. If you can source the parts, the hybrid you speak of is also a good option.|
|I'm compelled by rules to run essentially the stock caliper. It can be modified, but not changed.|
In the absence of P2500 caliper halves, has anyone attempted to increase the thicknes of the stock caliper inner. It scaled about 0.70", I'm thinking of taking a 0.20" cut on it to open the rotor width and spacing the outer the .20" to get the appropriate cavity thickness
|Greg , try Rover SD1 2 piston calipers ,they take BGTV8 pads & you can use std MGB brake master cylinders . Steve|
Get the triumph calipers from Oz. There are hundreds in the junk yards and they will be cheap.
Let me know If you have want and I can reasearch the postage.
Just scarpped a set of two piston SD1 calipers couple months ago when we pilled the V8 from it.
I live in Southern California- If not too much trouble, can you fins out what freight would be?
|And I guess I should read my messages to check spelling before I post them|
|Greg email me direct and I will price calipers on the W/E.|
It will cost you about $10 (US) per kilo for the brakes and I have no idea what they weigh but I have been meaning to get some for myself so I will buy and weigh and you can decide if the price is OK.
|You may already know this but the Triumph 2500 comes with both Girlock and Lockheed calipers. To start with I bought the wrong ones which will not mate with the MGB half. Make sure you get the Lockheed ones.|
|Ian G Buckley|
|Thanks for the heads up Ian, No, i didn't know- I'm not certain that the 2500's made it to the US in number sufficient for that information to be readily available here|
Do you know what year the cut over is or is it any year?
|Not sure about the changeover. Perhaps some just had one and others another! Someone told me some Triumph 2000 s have the right ones. I am pretty sure that Girling or Lockheed is cast into the parts. |
If you take half a caliper with you to look at the others it will be obvious that the bolts will or won't line up.
|Ian G Buckley|
|Does anyone know if the 4pot calipers from a 1985 SD1 would fit on a 79 B? I happen to have a complete SD1 that i am taking apart and i would like to use as much as possible from the car fore my V8 conversion.|
|This would mostly be of interest to the USA crowd, but several years ago (1995), there was a thread on the MGs mail list about Ford Mustang calipers fitting MGBs. The '72-'73 Mustang calipers were reported to be the same Lockheed, 4-pot calipers being marketed by Moss (and others) as an upgrade for the stock MGB brakes. They are supposed to be a bolt-on replacement, other than requiring an adaptor for the hydraulic fitting. Rotors would have to come from another source, as the Mustang rotors did not fit. MGB and V8 rotors both were reported to work with the Mustang calipers.|
|Interesting, and I'd like more information on this for my street car. Unfortunately, doesn't buy me much on the race car|
|Would it be possible to add a machined spacer between the two halves of a B caliper and longer bolts to end up with a wider setup?|
a machined spacer would not add to the width unless the actual part of the inner caliper half is machined where the disk runs. The inner "half" is a misnomer it is more like the inner "3/4" with just a cap holding the outer brake cylinder.
You would also have to develop some way of sealing this spacer in a similar fashion to the current seal.
Concur with Allan.
Simple answer is no. Putting a spacing plate between the two 'halves' would move the outboard pad away sufficiently, but the inner 'half' has a slot section cast into it. That slot section, where the disk runs, scales 0.49" on the girling calipers from MGB's that I've measured. Both sides of the slot are part of the inner one- piece 'half'. The BV8 rotor scales 0.50"- even if I turned it down to .46 or so (loosing some of the heat adsorption ability- the reason for going to the V8 rotor), there's not the .10-.12 design clearance between the disk and caliper. Possible to do- but shimming the caliper to get clearance- I see a large pain in the rear coming that can be avoided by using Triumph caliper 'half.'
I've also looked at Lockheed calipers as used on the MGC. Seal design on the pistons is probably not as good as the MGB Girlings. Minor difference in mounting hole centers- nothing that can't be addressed. The lockheeeds are actually alot closer to two 'halves' concept than the Girling- a distance plate properly sealed would open up the slot distance appropriately.
I'm not willing to give up on the Triumph calipers yet- but if that doesn't play out, I'll find a vented disk and space the lockheed calipers to center on it
Yes I fitted the Vitesse 4 pot calopers but:-
The Rover bolt holes are slightly larger than the MG bolts, so I had to use sleeves.
The MG disks are the wrong thickness I used Peugeot GT ventilated disks (I think I have the part no somewhere) and they have to be re-drilled to fit the MG stud spacing
Do you happen to know witch Peugot and what year?
Could it be the 309 GTI mid 80? Sorry if my spelling is not as good as it should be.
I will look tonight I'm sure I have the part no, off the top of my head, I think it was the 504GTi
Checked last night,Peugeot 505gt Ref No BG2227.
My disks are Lucas /Girling the part nO is DF 1210, they measure 275mm x20mm vented.
A few points to bear in mind:-
1) the Vitesse disk was 23.8mm thick, so the pistons are out rather further , so pads may need to be changed earlier than usual, as I'm not sure how much metal is still in the cylinder.
2)The disk is slightly offset, 1) and 2) could probably be cured by grinding a bit off the back of the disk hub, and having the spacer in the middle of the caliper reduced, I may get round to this one day !.
3) The brake pedal will go down further as more fluid is being moved, I have to say that I haven't noticed this paricularly.
4) The Peugeot bolt spacing is different from the MG so new holes will have to be drilled in the disk.
5)Flexible pipe connections are not the same so special pipes have to be made up.
6) The calipers are much wider than the ones they replace, and ordinary MG wheels will not fit. On the RV8 (which has a very similar caliper)they appear to hve solved the problem by bolting on a hub spacer, and drilling this to accept mew studs. I originally tried 2" spacers and stud extensions, but was never very happy, so ended up replacing the wheels with Minotaur 15"x6" which fit very well, the only downside is that they are too wide for the rear wheel arch, and this has to be flared, or at the very least, most of the inner lip cut off.
Good luck, I think the conversion is worth it. Roger Parker at MGOC who used to drive police motorway patrol SD1's (for whom the twin caliper conversion was originally developed) told me they used to stop them OK, I reckon an SD1 full of Bobbies and emergency kit must be well over 2 tonnes (no offence meant Roger) so it should stop a 1 tonne roadster no problem!
With your 4 pot SD1 calipers, do they single inlets or dual pipes? If dual, how did you rig up your lines? I have these pieces and am still unsure of the best way. I also have the SD1 master cylinder and am wondering if anyone have used this with their setup. If so did they use the SD1 proportioning valve?
Yes, you have to fit a diagonal crossover pipe to join the two sides of the calipers, or use dual lines , which I found too complicated.
I too had a SD1 master cylinder and reservoir, but the diameter was too large to fit in the MG servo, and the reservoir was tapered, so I went with the MGB ( late rubber bumper twin) master cylinder setup.
I think it's OK.
I also had the proportioning valve and considered using it, but the plumbing also looked complicated, so I just reduced the size of the rear cylinders to BGT size ( my axle is an SD1 cut down , and drum area is in fact slightly less than the MGB) So far no brake locking , so I guess it's OK.
I will keep all that in mind and try to fix it up the best way i can.
Thanks for all your help. It made life easyer for me.
Mike i dont think you shall use the valve because it is made for a much heavier car and will allow your rear wheels to lock up to early. To much power on the rear brakes.
Yes there is quite a lot involved with the swap, but I think it gives a big potential improvement in braking, and the wider spaced wheels must help the handling.
I got a chance to do some 'parade' laps at Silverstone at the MGCC meeting last month, and was very pleased with the braking, I doubt that I would ever use the brakes as hard on the road as I did there, but it's reassuring to know that it's available if required in an emergency.
I donīt think i will have any problems with my wheels because i use wheels from a shelby mustang and they will give me the space i need. 6 1/2 x 14. They gave me spacing problems before i cut away the inner lip but now i have 4 mm clearence. Byt they look GREAT.
This thread was discussed between 04/08/2002 and 15/08/2002
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