Recently I did some quick maintenance on a P130 with single brake circuit. Among other things I found the car pulled quite severly to the left while braking, indicating lack of braking force on the right side.

I checked the calliper: all fine (rebuilds, 2 years old). Checked brake lines: all fine. Bleeded the brakes: all fine. Everthing looked to be all right but car still pulled heavily while braking.

I will do some more work on this car later on. In the meantime I could think of more things that can cause the problem, but actually could not think of any that I did not check. Suspension and wheel allignment are ok to.

Anything that I might be over-looking??


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Daily driver: P130, '65, B18+M47. In the proces of restoring: P131, '69, B20+AW71L. (www.knutselsmurf.web1000.com)

An unbalance in the rear usually causes minimal pulling since the majority of the car's braking effort is in front. Soft suspension bushes can cause a "pull" that will be difficult to detect with a visual inspection and may require a pretty hefty application of force to reveal (so I wouldn't count it completely out).
Ditto for dragging brakes. The tests mentioned should give a pretty good indication of what is going on there.
It is also possible that the flexible brake lines are bad. Especially in a single circuit system, a minor blockage can have a big effect on brake application. Swelling lines can also cause difficulty, especially as you can't see it unless you are under there when the brakes are applied.
Check, also, the wear on the pads. Uneven wear can signal an ineffective cylinder that may seem OK when you look at them.

Mike!

Thanks for all reply everyone.

-When braking in need to grab hold of the steering wheel quite firmly so it doesn't turn and brake my thumbs. Also when applying brake force, the wheel on the left locks up with no problem, while the right one still turns. I think that would rule out the problems with suspension. I even tried swapping tires since they were from a different brand.

-Both discs are smooth and clean, pads are worn evenly, all cilinders in the callipers work ok. I also checked by moving the cilinders in and out and looking behind the rubbers.

-Brakes don't drag. Problem is not caused by over heating and fading, since it occurs in the first 30 sec (and after) I take the car for a ride. When I jack up the front, both wheels turn freely. All cilinders of the front callipers have no rust what so ever on them since there rebuilds. Same for the rear brakes, all in 100% good condition.

-I checked to see it perhaps the flexible brake hose was clogged up in the 'problem' side by bleeding them, but good flow. I can't tell if it might be swelling under presure, but even if it did, the presure in the lines itself would be same wouldn't it? Therefor it could not cause a brake difference, right?

Hmmm, I'm not getting it...
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Daily driver: P130, '65, B18+M47. In the proces of restoring: P131, '69, B20+AW71L. (www.knutselsmurf.web1000.com)

I remember reading something about this kinda problem years ago.

In a nutshell... lf a front line is swelling internally, the effect of the resulting restriction seems to have been like a time delay in the application of pressure at the brake (similar to a vacuum signal delay device in some emmisions control plumbing). Just a fraction of a second difference in application time, side to side goes a long way. Seems to me, the restricted line was on the front brake OPPOSITE the direction of the pull. I also seem to recall that the line itself showed no sign at all of bulging from the outside. The mechanic finally changed out the line and sectioned it in one inch sections and found only a very short distance (like an inch) that was restricted.

Sorry I am so sketchy, but I thought it might be worth contributing to the discussion.

I can sure tell ya that mis-adjusted drums in the front will make it pull... WOW!!! Me peepers bugged out and bounced offthe windshield.

Yeah, I think the rubber brake line might be the problem since it's the only thing that I have not been able to look IN to...

Once I start to work on the car again, I'll post what the cause was (assuming I solved it that is...)

In the mean time, if any can think of something else, I'd much like to hear it.

Thanks and cheers all, Ben
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Daily driver: P130, '65, B18+M47. In the proces of restoring: P131, '69, B20+AW71L. (www.knutselsmurf.web1000.com)

Good luck Ben.. Get some stainless lines... no swelling and they look cool too. LOL

A couple things come to mind.
One is that maybe the brake pads or disks don't have the same surface
characteristics (rust on one side, smooth on the other, hard pad on one
brake and soft ones on the other), etc
The other is that maybe one of the brakes is dragging and getting hot
enough to fade while the other one is OK. To check for this on your
next short trip check temps of hub and disk (carefully, you can burn
yourself) on both sides. If one side is a lot hotter than the other
you might check to make sure your brake line is not acting like a check
valve. If it is, you can open the bleeder and the hydrostatic head will
not be enough to make it drip.
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George Downs, Bartlesville, Oklahoma, Central US

¿rear cylinder locked?

I'll assume your rear brakes are in proper adjustment...? Any signs of leakage of any kind that could be leaking on the brakes front or rear?

It is also possible (though would have to be rather extreme) to have a problem with suspension which moves the alignment under braking forces... but I doubt thats the problem in your case.

-Matt
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-Matt '70 145s, '65 1800s, '66 122s wagon, others inc. '53 XK120 FHC

Yeah, a brake fluid leak will cause grabbing, leading to a pull TOWARD the affected side.
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Jim McDonald