MGB & GT Forum

I've searched the site on overhauling brakes. I've also looked at some videos.

I think I know enough for my son and I to have a go at overhauling the front and back brakes on our 74 GT.

My friend, the previous owner, thinks that the calipers have never been replaced. The odometer shows 72k; she says that is the actual mileage.

How do I know if I can use the calipers that are on the car right now? If I can't use them as is, should I rebuild them or replace with new?

Thanks.

Bob

Replace with new. They are so inexpensive now it is prudent to renew everything.
replace rotors at the same time and install new flex lines,flush system,bleed air,bed the new pads and rotor in properly.
Rears replace slaves and shoes inspect drums.

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Bob, here is how I see it.
I am going to do a brake overhaul on Friday. When I have the calipers off I will use compressed air to remove the pistons.
If the pistons are pitted or rusty I have the choice of buying new pistons and seals or buying new calipers.
If the pistons are bad then new calipers.
The piston and seal kit is $30 and the caliper is $80.
If I can just install new seals fine. But if they are all rusty and it looks like I might have two or three hours in it, It will get new calipers.

I bought a master kit and rebuilt my own. Frankly I trust my own work more then the work of a random rebuild shop across the seas who is banging them out as fast as possible. That said, I took ASE brake and suspension classes once I got serious about this hobby.

Drive the car as is.

Check brake temperatures with an infrared thermometer.

130 front, 115 degrees rear. Both sides are the same.

Calipers last a long time. They are the toughest part of the system.

If in doubt, replace them. Usually a little over $100.

Usually they begin sticking on one side.

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L.W.(Larry)Baygents
63B
77 Spit

Calipers is not something I would rebuild as a first timer. If you have done it before then all well and good.
They may not need rebuilding anyway. As long as the seals are good, they don't leak and the pistons are not stuck then you are good to go. Calipers are not an age thing, the rubbers perish and they leak, the pistons score and rust (with dirt) and they stick. Other than that they are very reliable. Keep them clean and full of fresh fluid and they will last for a very long time.

I chose to keep my calipers but everything else is new. You may read that splitting the calipers is a no no but that's an urban myth. You can't replace #3 without splitting them - but I did keep the parts of each caliper separate from the other. You may care to use ss pistons. There's some conjecture about retaining or replacing #2 which was discussed a while back in a rotor option topic (stock v slotted v slotted and dimpled).

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Mk1: CKD 11/66 first registered 8/5/67; owned since 3/77. 18GB +40 balanced. Peter Burgess BVFR head. Piper 285. 123. FidanzaFW. 4synch c/r box. Lots more as I did a nut and bolt rebuild; finished 2015. Tartan Red.

GT: December '78. VW Golf guards, flush fit front and rear valances. Torana XU1 vents, frenched indicators & Mk1 rear lights. 'Worked' Rover V8 with Monsoon ECU for EFI. GM4L60E, Lokar tiptronic & Quick4 controller. Vintage Air A/C. FC IFS. CCE 4 link rear. Salisbury with Quaife. Jaguar Storm.

I could have edited my post above but if you're getting the updates via email you'll miss the edit so I added a new post. If you rebuild you may need to take note of this - it refers to the orientation of the cut out in the piston. in the end I followed the manual's advice and not the maker's advice.

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Mk1: CKD 11/66 first registered 8/5/67; owned since 3/77. 18GB +40 balanced. Peter Burgess BVFR head. Piper 285. 123. FidanzaFW. 4synch c/r box. Lots more as I did a nut and bolt rebuild; finished 2015. Tartan Red.

GT: December '78. VW Golf guards, flush fit front and rear valances. Torana XU1 vents, frenched indicators & Mk1 rear lights. 'Worked' Rover V8 with Monsoon ECU for EFI. GM4L60E, Lokar tiptronic & Quick4 controller. Vintage Air A/C. FC IFS. CCE 4 link rear. Salisbury with Quaife. Jaguar Storm.

Frankly I will change them if I was you. 60% and more of the braking action is on 2 calipers; after 30 years and more it is time.
Take the opportunity to renew the disks, pads as well, soft hoses.

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1977 MGB Red 'Victoria' and 2018 Jaguar XE 'Meghan'
All Classics:
Married, 2 children, MG MGB May to December, Jaguar the rest of the year.

X2 on replacing only what you have to.

The only thing that makes rebuilding the calipers hard is not having the right tools -- and not following directions.

Get the Haynes manual if you don't have one. Also recommend getting the caliper tool (the clamp for seating pistons and seals) from Moss. Read the directions and rehearse it once before you "go live".

If they are corroded or pitted they should be changed.

If they are not corroded AND you are competent, meticulous and have the proper parts to do the job it is quite possible to rebuild them.

I tend to agree with Jared about trusting my own work - but I've been working on cars for over 40 years. If you don't feel confident working on a braking system then just get new ones. The cost isn't high and these are your brakes we're talking about! Much better to spend an extra $50 than to mess up the job!

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Terry Ingoldsby
terry.ingoldsby@DCExperts.com

Robert,

X2 with what Roger says with one exception... There are 2 seals (inner & outer). The outer seal (dust seal ) uses a thin metal ring that sips around it and helps hold it in place. Just be CAREFUL when you use compressed air to blow the pistons out. They have a habit of sticking and them letting go suddenly which sends brake fluid flying everywhere! It helps to place a piece of 5/8" or 3/4" plywood (or some other thick material) in between the pistons (keeps them from launching completely out) and gently add air via the brake line port until you see some movement. Once you see them move add a little more air until they touch the "spacer" you put between them. Remove spacer and finish removal, just watch out for flying fluid when they "POP"! If the grooves are smooth after cleaning them and the pistons are not corroded then a seal kit is cheap! Why throw away good cast iron? Also note the pistons are not fully retracted even with new brake pads so if the outer edge of the pistons show some minor corrosion this is not a problem either just as long as it will not come into contact with the new seals... Just clean it up if you want without damaging the good chrome. I just rebuilt mine using S/S pistons.

Then again, if the pads are good, and the calipers don't leak why even bother with it. Brake calipers aren't known for catastrophic failure. There are vehicles out there with over 100,000 miles on them with original calipers (I have two) and they work just fine... What may be more important is knowing when the last time the brake fluid itself was changed!!! It's all about "preventative maintenance". If brake reservoir fluid level drops, you know it's leaking somewhere.

Just my 2 1/2 cents worth...

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Those who confuse Burro and Burrow don't know their @ss from a hole in the ground...

normally calipers don't wear as you might think they would. the wear points are the pistons and seals. some pitting in the bores isn't going to hurt anything. (nothing slides against the bores)

Drake,

I agree that pitting in the bores is fine, just not in the seal grooves... This can cause fluid seepage/leaks. I recently rebuild the front Performance Machine caliper on my H-D. Leaked... I was not too happy considering these calipers cost in the region of $400 or so. In the end I removed the pistons and seals once again, took a "toothpick" style wire brush, cleaned out all the grooves and reassembled/bled the caliper. All was good! The wallet was very thankful...

Paul

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Those who confuse Burro and Burrow don't know their @ss from a hole in the ground...