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MGC Brake upgrade? Am I nuts?

Posted by Limey in Hawaii 
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Limey in Hawaii Avatar
David Hume
Kailua Kona, Hawaii, USA   usa
1968 MG MGC
OK, I just found this site and am very happy. As far as I know I own the only running MGC in Hawai. I have owned four in the last thirty years but only one remains, salty air is a killer! None of my cars have had good brakes, no boosters or only one on the fronts. Now the plastic on the m/c resevoir is cracked and does not hold fluid. My solution is a modern system, a dual diaphagm 7" booster on a 1" Corvette master cylinder. Of course there is no room so I propose to build a crank linkage in the pedal box to put the actuation force 90 deg across the car. My car was built with no heater box so that is not in the way. The booster, m/c would sit across the car on the flat before the bulkhead, in front of the passenger...AM I NUTS? or could this work. I don't care about originality, I just want better brakes. I am also considering the larger Toyota landcrusier calipers. Any thoughts, any input on the Toyota calipers?....Lastly where can I get an exhaust header system? I would like some throaty dual pipes. I had an XK120 decades ago back in the UK and that sounded terrific. Thank you and Aloha, David, Big Island, Hawaii.

ron neal Avatar
Coastal, South Carolina, USA   usa

Talk to Kirks-Auto, Robert can advise you what parts are available and what works, personally, sounds like you are trying to make this hard. I would go with some modified MG setup, they stop fine. There are some posts on brakes if you scroll down and look them over, this might help.

Can you fix the reservoir? Not familiar with toyota calipers. Headers, again ask Robert, they can be bought in the UK from a few places but will need a little work to clear the US intake manifold. Moss sells a set.

Good Luck, my vote, yes you are nuts. I think there is an easier way. I was stationed on Oahu for a couple of years back in the 60's and 70's. great place, big island is even better.

Cheers Ron

mgcsaylor Avatar
Mark Saylor
Pennsylvania, USA   usa
1969 MG MGC "Pride and Joy"


Can only 2nd what Ron has to say.

As for Cs in Hawaii, I know of one other on Oahu. The American MGC Register has had 8 Hawaiian members over the years, only one is a current member, so chances are your car, and the others, may have been owned by one or more of them at one time.

Recommend you research this Forum and the MGC Bulletin Board at before you change your brakes. Between the two there is alot of information on this aspect of the MGC, and every other for that matter.

And while I'm at it, please email me at so that I can invite you to join the American MGC Register, of which I'm the Editor.

Safety Fast!

Mark A. Saylor

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Robert Kirk
Davenport, Iowa, USA   usa
You are throwing a lot of $ at the problem it sounds to me. FWIW Corvette use PBR servos and i happen to sell PBR servos to replace the Girlings. The benefit if they are remote and could actually be plumbed to work in the boot if needed. I thing the vette set up is a single in total mandatory thing.
The plight of your BMC may also not be as bad as you suspect. PM me about a certain alternative I may have in stock.

Can't help with Toyota but I suspect when you have a working dual HD twin servo set up you will be amazed at the ease of hauling down the C Horses. Your front brakes have been handling TRs since about 1960, Healeys in the final form, MGCs and possably V8 Tigers...who do also use the same servos.

I can also help with a header and or downton exhaust system and or a triple downton SU intake. Thanks Ron for the mention.

And while you may have less to bluster about, I am quite sure you are the only Hume in possession of an MGC in the entire South Seas! Hope that claim fetches you a Pint sometime!

Robert Kirk
563 323 1017
Moss distributor UK importer
Beat or match any retail/delivered quote

Member Services:
Parts for your classic British and Italian car. 30 years in business.
PaulP Avatar
Paul Peterson
Seattle, WA, USA   usa
1973 MG MGB GT
1974 MG MGB
Jay Musgrove posted some pics awhile back of his conversion to a non-powered system w/ a revised pedal ratio.,738722,807077#msg-807077

Others (PaulM and bills) have posted pics of their C's with a single booster.

Edited 1 time(s). Last edit at 2009-07-30 02:14 PM by PaulP.

Limey in Hawaii Avatar
David Hume
Kailua Kona, Hawaii, USA   usa
1968 MG MGC
Hi guys thanks for the responses, I feel like I have just made a lot of new friends. Mr Kirk, I will write and enquire about what you have to offer. On the other hand, my solution is very inexpensive. The dual diapragm booster and Chevrolet/Corvette master cylinder can be delivered to my door for $200...brand new, modern tecnology. All I have to do is fabricate a linkage, and I have the skills to do that. I know that the original system is good when working, but two new boosters plus a rebuilt master will run me well over $1200, and how long will they last? I have a 1971 Cadillac Eldorado and there are no issues with brakes there. It is just that the dual circuit, remote booster system offered to the US seems like an afterthought...and all of the cars I have owned had booster issues. Have you ever taken a booster many bits and pieces to go wrong. So back to my original post. Will a 1" dual circuit master cylinder with a 7" doudle diaphagm booster work, be too much or what? Over the years I have been let down time and again by the MGC's dodgy brake system so I want to upgrade it. I ran for years without boosters but the girlfriend can't drive it like that. The only other alternative I like is the idea of changing the pedal ratio to 6:1. Thanks again for the input, I will keep you informed. Aloha David Hume.

ron neal Avatar
Coastal, South Carolina, USA   usa

I am not sure about your corvette parts question as I know nothing about them.

Cheers Ron

Edited 1 time(s). Last edit at 2009-07-30 04:33 PM by ron neal.

Robert Kirk
Davenport, Iowa, USA   usa
For $200 and the work involved you may have an easy answer to the issue. I certainly can't offer anything that affordable...I charge $200 for you to consult with Ron or Rick...checks accepted!
OH YES, welcome to the forum and this is a whiz bang bunch of good folk!

That said, a lot of folks will offer "solutions" to the OEM design that I frankly would not endorse for a number of reasons. When its time to grab the brake handle, almost, nearly, should do, ought to do, could have done, should have done, was the cheapest I could afford, just doesn't aswage the problems of hauling the beast to bay. A power ship's anchor in the tow could also work well IF its deployed in time. I am being fatious but I hope you garner my meaning here. Don't get "close" on the matter. Lawyers and victims are abundant to most if not all the above. Modifying brakes on an automobile is an actual cause for those who make a living pursueing such, at least in the USA.

If it can stop a modern vette, it will certainly be able to stop a 69 C! Please be aware of the plumging end differences to hydraulics...THEY ARE DIFFERENT. Otherwise, your solution as stated, seems doable enough and downright thrifty to anything I know or can offer. In fact, if so, its a great solution!

Good luck! When you decides to properly uprate the suspension I am the only one in both the Pacific or Atlantic with all positions covered...FWIW.

Robert Kirk
563 323 1017
Moss distributor UK importer
Beat or match any retail/delivered quote

Member Services:
Parts for your classic British and Italian car. 30 years in business.
trymes Avatar
Tom Rymes
Concord, NH, USA   usa
My concern is that you state that none of your Cs have stopped well. Both my C and my B stop quite well, even though the C has B brakes and a disconnected servo. I'm thinking that you have a problem that is larger than just MC and servo issues. If you can lock all four wheels as-is, you can't improve upon that, except in pedal effort and fade-resistance. Pedal effort is MC and servo related, and fade-resistance isn't something you need to worry about in everyday driving. If your problem is only that pedal pressure is too high, and you don't want to deal with servos, then I would suggest that you look to an MGB pedal box and unassisted ('68-'75) brake MC (presuming that the bore size displaces enough fluid for the C brakes, which I think it does; this has been done before!).

On the other hand, if your stopping problems are something other than pedal effort, you could have a brake problem, such as seized wheel cylinders, calipers, improperly installed rear brakes, etc.

Most likely, however, is that you have badly adjusted rear brakes. IIRC, the C normally has self-adjusting rear brakes that are anything but self-adjusting. If your rear brakes aren't properly adjusted, then your fronts are doing all the work, and your brakes will be "underwhelming", to say the least. What happens if you depress the brakes, and then quickly pump the pedal once?

An unmodified C should stop just fine. A C without servos should stop just as well, the only difference being how much force is required to depress the pedal. Before you go fabricating something that is an unknown, find out why your car isn't stopping with the standard brakes, because the standard brakes are pretty darned good.


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Limey in Hawaii Avatar
David Hume
Kailua Kona, Hawaii, USA   usa
1968 MG MGC
Robert, good advice about the legality of major modifications to the vehicle. I think it would be more pertinant if I was down grading to a single circuit system not allowed in the US or just runnimg without working boosters, which have been doing. I love to drive my MGC, I just would like a better brake system that I can instal and forget about, just like my truck and my Cadillac. I will let you know how it goes...Oh yes, these is not specifically Corvette parts, it is just that a Corvette uses a 1" bore MC, the booster comes from Hot Rods USA, I think it is Wilwood brand. Thanks for your time, Aloha David.

Big6Mark Avatar
Mark M
Emerald Valley, OR, USA   usa
1960 Austin-Healey 3000
1968 MG MGC "Red Tail"
1968 MG MGC
1968 MG MGC GT "The Wreck"
1969 MG MGC GT "The Lump"
Wish I had known where you were a couple of years ago when I was on the Big Island. Would have liked to stop and visit...
Your car must have been an original Hawaiian MG as the cars sold in Puerto Rico and Hawaii did not have the heaters as the rest of the States did (not really an option).
I think your problems are more a problem with your location than the parts on the car.
If I were you I would attempt to rebuild the system and seal it off from the extreme humidity on the islands and the salt air. (I assume you live on the wet side of the island, around Hilo?) This is the reason the MG parts fail and the newer systems don't: the cap on the reservoir is not sealed off from the air on the old system as it is on the new ones (Corvette, Caddy, etc.)
You can retrofit a diaphragm seal to the reservoir cap to keep the humiditiy and salt out and if you were to use silicone fluid it might last a long time. And lots of silicone brake cam grease on the air side of the seals would help, too.
Properly built, the MGC brakes are quite good.
As an alternate, the Toyota calipers are practically the same for piston area, so the brake clamping pressure would be the same. Only advantage is a larger pad area. Disadvantage is that the threads are metric.
The MGB caliper is also the same size, so an MGB pedal and master cylinder conversion would also work essentially the same as the original. Only cost or convenience would be different.
Hope this helps.
C Ya,
Mark Miller
AMGCR Tech Editor

Limey in Hawaii Avatar
David Hume
Kailua Kona, Hawaii, USA   usa
1968 MG MGC
Mark thank you for your reply. I live on the Kona side as it happens and I have tried all the tricks you mentioned. I have owned MGCs here for twenty five years and am just fed up with trying to maintain this system that is forty years old. The master cylinder bypasses, the resevoir is shot, the silicone leaks straight out onto my feet and the rebuilt servo, fronts only, is leaking fluid yet again. At a cost of about $1500 I can completely re build this ancient system.....or for a couple of hundred bucks I can have someting brand new and modern. Not too much of a choice realy. I just have to fabricate a strong and reliable linkage. I have built a couple of Cobra replicas and was involed in racing a long time back so I know that 'anything is possible' I will post some pictures when I have the wrinkles ironed out. Aloha and thanks again, David Hume.

bills Avatar
Bill Spohn
W. Vancouver, , BC, Canada   can
David - we used to have a place near Kailua Kona above the Kuakini highway!

If you don't mind oly having single circuit brakes like the home market cars, the solution is dead easy. Use a Triumph master with integral reservoir and the single servo. Brakes work great. Cost under $200.

Bill Spohn
1958 MGA Twincam (race car (170 bhp)),1962 MGA Deluxe Coupe (98 bhp)
1969 MGC roadster (175 bhp), 1957 Jamaican MGA (200 bhp)
1965 Jensen CV8 (375 bhp), 1971 Jensen Interceptor (350 bhp)
1969 Lamborghini Islero S (350 bhp), 1988 Fiero GT turbo (300 bhp)
2009 Pontiac Solstice GXP Coupe (350 bhp)
West Vancouver BC

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