Brain Challenge!!! 75 Eldo Front-End Stumper

[Jeff Pendleton CLC 22056]

Man, I am about to do something desperate if I can not get the front end fixed on my 75 Eldo.  Here is what is happening:

I bought the car 5 mos ago, LF wheel squeaked when I drove it and I could smell the brakes.  I have had two previous eldos with brakes line probs that locked the front brakes, so, #1 replaced brake line..no help,  Okay #2 replace caliper, rotor and pads just to be safe...no help.  I thought you-gotta-be-kiddin-me!  Okay, bought new front hub bearings..the machine shop said my hub was bad.  Great, thats got to be the problem, right?  Hunted-down a good hub put it all together.  Its quiet now, but still excessive heat at that wheel.  Way too excessive, and still smell the brakes.

My guess is what ever is causing the heat ruined the bearing seals and ultimately the hub.  So that was not a waste of time.  But what else could it be??  This is crazy.  If you told me I would spend $400 and still not have this solved, I would have told you you were nuts.  But now, its me whose nuts.  So please, lets put all the great minds together and try to figure something out.  

You all are the greatest!
Jeff 816-309-5333

[Bruce Reynolds # 18992]

Gday Jeff,

Sounds like you may have something causing the brake pads to stay applied to the Disc rotors.

If you jack the car up, can you spin the wheel by hand?

I realise that it is front wheel drive, and there will be a fair bit of resistance from the transmission and differential, but you should be able to turn each side, one at a time, reasonably easily.   And, as the car doesnt have an LSD, if you have someone on the other side, spinning that wheel in the other direction, it will make it easier to turn your wheel.

If the pads are binding, remove a wheel and with a screw driver, carefully prize the pads away from the rotors so that thet are clear of the Rotor.   Put the wheel back on, turn it again, and if it is markedly easier to turn, then the pads were binding.  (it is easier to turn the rotor with the wheel on as it gives more leverage, and the tyre is easier on the hands, unless the tread is through to the steel belts, then the wire ends can be painful)

Now, with the engine off, apply the brakes a few times to expel all the vacuum from the Power Brake diaphram, and apply the brakes a few more times, then release the brake pedal, and see if you can turn the wheel again.   Then, try it again with the engine going so that the power assist is operating.   If it is tight to turn, either or both times then there is a problem with either the Caliper Piston, Booster, or the Master Cylinder.

When the Brake Pedal is released, there is no brake line pressure to the pistons, and the only way that the pad to rotor clearance is obtained, is for the rotational movement of the rotor, and slight slackness in the wheel bearings to "tap" the pads ever so slightly away from the rotor surface.

But, as you have replaced the lines and the Caliper, then it is time to look at the M/C and Power Booster.   And you mustnt rule out a pedal that is constantly applying pressure to the M/C.

One last check of Piston Pressure would be to, after the pedal has been released, "crack" the bleeder screw, and see if there is any brake fluid coming out under pressure.   There should be none, as the pads are in "resting mode".

Bruce,
The Tassie Devil(le),
60 CDV

 

[John #22631]

Hi Jeff,
 In the lines coming from the M/C, follow the one from the rear of the M/C down to the proportioning valve. Where it splits off from the valve follow the one leading to the wheel in question looking for any crimps or kinks in it.

  Also dont rule out the flex line from the frame to the caliper. They are constructed with multiple layers and the layer on the very inside is known to collapse. This is a cheap fix.

  As Bruce said, the M/C itself could not be fully returning back to resting mode, therefore keeping constant pressure on the pads. And it doesnt take much to keep the pads from binding with the rotors. I would think that if the booster was going bad it would affect all the brakes. Thats why Im going for the flex line as the culprit.

  Good luck and let us know how you made out!

[Kevin Bielinski]

else this happened to. It turned out to be a problem with the valve. He rplaced it aqqnd that was the end of the problem.

[Jeff Pendleton CLC 22056]

I can spin the whel by hand.  Even when hot it does not seem to have THAT much resistance.

Regarding the MC, Booster and pedal.  True these could be problems, but how do you check them?

[Jeff Pendleton CLC 22056]

I replaced the flex line, no kinks in the steel lines.

Keep the ideas coming!

Thanks, Jeff

[Jeff Pendleton CLC 22056]

Do you mean the proportioning valve?  Are these avialable?

[denise 20352]

  Jack up the corner of the car.  Apply the brakes hard and let go.

  Try to spin the wheel by hand.  If the brakes are holding it, crack the brake line at the master cylinder.  If the brakes let go, then the master cylinder is the culprit.  If you can spin the wheel easily, then its not a master cylinder problem.

   Thats the master cylinder test.  If you do it with the engine running, the same test should tell you if the booster is causing the problem.

   Normally, either one of these things would affect both wheels, though.

-denise

[Jim Skelly, CLC #15958]

Replace the black flexible hose on the other side, too.  As indicated earlier, the hose is composed of layers and these deteriorate from the inside and look good from the outside.  I had a similar problem on my 77 Eldo a couple years ago and that cured it.

68 Eldo & 77 Biarritz