PLEASE HELP! Front disc brakes are still locking solid after about a mile of normal driving NOW FIXED

limey222 · October 03, 2015, 05:28:19 PM

I really thought I had solved this once but the car is totally undrivable, because of this still unresolved problem.

Many of you have tried to help but so far it has beaten the brightness minds on this and the MGExperience forum so this is a challenge.

This is what I done so far:

Tried Two new brake master cylinders
Moved the MS back in the pedal box with spacers to ensure free play in pedal (some suggested this)
Replaced the "shuttle" valve with reconditioned unit from UK
Replaced both front caliper assemblies (with beautifully rebuilt ones).
Flushed the system and blown-out all steel lines
Used new Castrol DOT4 fluid
Multiple bleeds

And most recently because the fault had sings of being thermal problem, insulated the steel lines and relocated them even further away from the headers.

The way the symptom occurs is that from cold start within a mile of driving at normal speeds in residential areas with stops signs the front brakes begin to drag and very quickly incrementally get worse until the car can't move.

After spending thousands of dollars and countless hour of work I can't use the car at all. PLEASE HELP!

limey222 · October 03, 2015, 07:22:27 PM

OK, in an act of total desperation I added a second 1/8" shim between the master cylinder mounting flange and the vertical member of the pedal box. Thus means that I have pushed it back a total of 1/4" now....... and darn me if the problem seems to have been fix. When I added a 1/8" s[acer a week ago and it solved nothing I never revisited it. After all I had a good amount of pedal play before the brakes began to actuate, now I have a lot more! All I can think of is that the clevis shaft that bought new off Ebay was made too long.
I'll still be holding my breath for the next week just to be sure.

88v8 · October 04, 2015, 04:50:19 AM

That's a really annoying thing to trip over.
I see Moss sell the single-circuit master with an attached clevis rod, but the dual cylinder comes bare.
Be nice to have one that's adjustable so the pedal play can be minimised.

I would guess you've fixed it now.
Fingers crossed.

Ivor

limey222 · October 04, 2015, 04:16:02 PM

Still working good..that's three short trips and counting. I may actually have permanent fix. Would love to use it this afternoon to go into town, the weather is beautiful but I broke my brake light switch yesterday while troubleshooting. They are so cheaply made and fragile. Will buy yet another one and install but I'm going to look at installing a 12 volt proximity switch in its place down the road. In the meantime trying to stay out of traffic, don't want somebody rear ending me because of no brake light.

BlownMGB-V8 · October 04, 2015, 05:52:53 PM

Proxes are available with a 10mm thread, see if you can source one with a 3/8" fine thread to match the hole in the cover. Those could become popular.

Jim

mgb260 · October 06, 2015, 06:25:55 AM

There is a aftermarket street rod brake light switch. You simply drill the hole out in the cover and use a nut on each side.

http://www.summitracing.com/parts/prf-80172/overview/

limey222 · October 06, 2015, 09:19:49 AM

I just purchased one from Napa and chased the tapped hole in the cover out with a M10-1.25 tap. It works great and is a more durable than the originals that have broken on me three times now.