1063P What caused right front brake failure

Here is what happened last weekend:
My mechanic and I drove my GT40 last weekend and on exiting the highway, I found that I had no brakes, so I started pumping and got about one inch of brake pedal. I turned around and entered the highway and found that I had full brake pedal. But after a few minutes saw white smoke billowing out of the right front wheel well and the car was pulling to the right. Once I got back home, I took off the Borrani wheel and saw that the brake caliper pistons (2) were tight up against the rotor. After cooling down the very hot rotor, My mechanic tried removing the wheel drive pins/studs (6) with allen (hex) wrench 'females', holding on the splined hub. The first one snapped off even with the rotor. And the 2nd and the third. Of course I was upset. At the time we did not see the capture/locking nuts on the back of the rotor, plus there was a type of "lock-tite? on the thread. The mechanic went home and I hired a "front-end" auto mechanic. He saw a two to three inch metal cap secured by a 2+ inch cir=cliip on the back of the rotor. After two hours of trying to remove the Cir=Clip, he finally was successful in removing the metal cap and Cir-Clip. But the next hurdle was a 2 inch nut and tab-washer (a 2 inch washer with two tabs extending from the washer). With a two inch+ open-end wrench he removed the nut and then the large washer. To our shock we saw that the 3/8 inch UNF drive pins/studs were retained by nuts that look like little "caps", fastened to the drive pins/studs on the back of the rotor.
I am having the rotor ever so slight "turned". I use silicone brake fluid.
I have no idea why the above happened. The other wheel (left side) did not share the same problem as the right side, so that in my mind rules out a bad Master Cyl. The rubber brake hoses are over 20 years old (I will replace them IF you help me find the same design ones-see photo below. The caliper (two) pistons are clean and unscratched. I replaced the square rubber seals in the cylinders' walls of the caliper (the old ones appeared clean and normal).
Please look (in following email) at the rubber dust covers with retaining coil-springs, located at the ball joints. My dust covers have ruptured/rotted and need replacements. Can you help me find those rubber dust/dirt covers with small coiled retaining springs-see photos on next emails.
 

Rick Muck- Mark IV

GT40s Sponsor
Supporter
It is very possible that the brake hose on that wheel end has failed and the inner lining is working like a "check valve" allowing pressure to the caliper but not releasing. This is a not uncommon problem with rubber/cord type brake hoses.

Getting exact as used by FAV hoses may be an issue but I think Bob Ash has had them done in the past. I would be more concerned with the functionality of the hose as opposed to the "concours correctness" of the hose. As it is a "bolt on" item you are not impacting the originality of the car.

Also why silicone fluid? While it does not harm paint, it also does not absorb water. The original selling point of silicone was the fact that it is non-hydroscopic. In fact you WANT the moisture to be held in suspension by the fluid so it can be drained when you flush the system (you do of course flush and refill it every two years or so, right?) with silcone (DOT 5) the moisture/water will pool at the lowest spot in the system.......on a GT40 that is the master cylinders. So the water now has lots of time to pit and destroy the masters!
 

Ellis Hubbard

Lifetime Supporter
I had the same problem with my Lamborghini Diablo and it was the brake hose. I replaced both of the front brake hoses and it solved the problem.
 
We have to suspend you for two days for saying Lamborghini on the forum. He he isn't there a rule for that? Can I have a rule check.
 
Barry, sorry to hear of your issues. When ever I hear/read of issues with an original I admit I cringe just from the thought. My .02 would be to contact Gelscoe in England. They are known for their originality with their cars so this might be a viable option. Good Luck sir.
 
Barry, that does indeed sound like a failing brake line as Rick says....in other words, the line is swelling internally and not allowing the caliper pistons to return to the passive position....causing drag and most importantly, heat....and expansion.

It may be a little more complicated than that...there may be little/no "play" in the system at the MC thus when the calipers get hot and expand there's nowhere for the expansion to go other than for the pistons to clamp down on the rotor even more. The MC needs a little play/slack in the system....not a lot...to allow for the heat expansion of the calipers/fluid.
 
It may be a little more complicated than that...there may be little/no "play" in the system at the MC thus when the calipers get hot and expand there's nowhere for the expansion to go other than for the pistons to clamp down on the rotor even more. The MC needs a little play/slack in the system....not a lot...to allow for the heat expansion of the calipers/fluid.

FWIW, I had this exact problem on my GT350 clone after I installed a new/different master cylinder. I failed to allow for free play at the pedal, and as a result the brakes were slightly dragging all the time. As they heated up, there was no room for expansion, so the brakes applied themselves more and more, causing more and more heat, and eventually they simply locked up and the car wouldn't move! I had to sit there for 45 minutes and let them cool off, then drive home, and the car was barely capable of mobility when I got it home, with the rotors sizzling hot.

The point of this story is that a problem of this type affects the brakes equally--that is, excess pressure caused by a maladjusted master manifests itself at two opposing wheels (as a minimum) if not all four. In this case, there was only a single dragging brake, indicating a problem downstream of the T-junction where the single front circuit line out of the master splits off to left and right sides.

I, too, would suspect the brake hose to be the culprit, although I have had friends with similar problems caused by rust/pitting in the calipers, and resultant sticking pistons.

Silicone brake fluid is not suitable for cars that are to be driven, IMHO. It is a formula designed for museum pieces. Reportedly it delivers a mushy pedal, and as mentioned above, its inability to absorb water, which is nominally described as a 'feature', is in fact a major 'bug', as the water is still absorbed but then concentrated, which allows it to create all sorts of havoc with critical components.

Flush it, then flush it again, and replace with a high quality DOT 3 or DOT 3/4 fluid (Ford-brand fluid, available from your dealer, is actually quite good and reasonably priced, although I prefer ATE fluid myself, because it's available in two colors, easily allowing you to distinguish when the old fluid is flushed and the new fluid is flowing through the system).

Sounds like you tore up a lot of pretty special pieces in order to get to the root of your problem. I hope Bob Ash or Gelscoe or Jay Cushman can get you the parts to get you back on the road again!

Good luck, and we look forward to hearing of your successful resolution!

Most importantly, I'm really glad to hear you are DRIVING P/1063. That's what it's for, and unfortunately more than a few original GT40s have been condemned to lives as static displays or museum pieces--a sad fate!
 

Terry Oxandale

Skinny Man
I also experience the mal-adjusted brake issue. Once the piston is moved inward just a bit off the pedal stop, the piston/seal assembly blocks off the port going to the reservoir, and now you've got a closed system that cannot release the pressure or fluid back into the reservoir.
 
don't forget the front wheel bearing has now been disturbed and will need sorting out/adjusting properly.

they actually have preload rather than a slight amount of play like most front wheel bearings.

i think i was told 7 thou preload (it was a while ago). but ring Gelsco anyway to make sure i remembered correctly.




it does sound like hose trouble so it'll be best to change the lot anyway and get rid of that silicon fluid. problem is that you will need to change the seals in the brakes now anyway so it'll be a good idea to do the lot and not have any future problems.
 
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