Right Front Brake Dragging?

[GregBurns]

Had front shocks rebuilt a week ago and car's been running fine. I've probably put a hundred miles on it since with no problems. Today took a short drive with my main-squeeze to get breakfast. Something like six miles there and six miles back. Took it slow and easy the whole way.

During the final couple of miles I noticed a slight, but perceptible, pull to the right. By the time I pulled into the garage there was a very slight smell of toasted brakes, and when I peered under the car from the front a few wisps of smoke were coming from somewhere right around where the brake line goes into the caliper.

Any clues what's going on? Any common faults I should look for?

Thanks,

Greg

[Steve Simmons]

My guess is that you damaged a brake hose and it isn't letting the pressure fully release from the caliper.

[GregBurns]

My guess is that you damaged a brake hose and it isn't letting the pressure fully release from the caliper.

I'd think if that were the case it would also prevent pressure application, which would mean when the brakes were applied it would pull left. I've felt no pull during braking, only a slight pull to the right when driving.

The Haynes manual in the fault diagnosis section suggests (among other things): caliper piston siezed. Maybe I'll jack it up and take a look (rotates freely when off the ground?)...

GB

[GregBurns]

Jacked front of car up. Hoses and everything else looks normal (at least to my eye). Both wheels seem to spin freely with just a whisper of the pads on the discs. Weird. Maybe I'll take it out again to see if another test drive duplicates the issue.

My only guess at this point is that something (perhaps some particulate contaminant in the brake fluid) got introduced to the caliper and temporarily froze it, not in a "full on" position, but in a "slightly more than normal" drag position so that there was some residual pressure between the pads and disc. May be an indication that the front calipers need to be rebuilt.

Sigh.

[Steve Simmons]

It isn't unusual for a hose to look fine on the outside but be collapsed on the inside. This usually happens when they get very old. The pressure you apply with your foot is far greater than the pressure applied by the system to return the fluid to the reservoir. Therefore the fluid can pass through the collapsed hose but become unable to return again. The pressure will often bleed off slowly, but in the meantime the brake is dragging and heating up. After sitting for a while, the pressure is released and the wheel spins normally.

Not saying it's a hose, just that it could be.

[GregBurns]

It isn't unusual for a hose to look fine on the outside but be collapsed on the inside. This usually happens when they get very old. The pressure you apply with your foot is far greater than the pressure applied by the system to return the fluid to the reservoir. Therefore the fluid can pass through the collapsed hose but become unable to return again. The pressure will often bleed off slowly, but in the meantime the brake is dragging and heating up. After sitting for a while, the pressure is released and the wheel spins normally.

Not saying it's a hose, just that it could be.

Good thoughts, Steve. Thanks for posting. I've looked at the brake lines a little closer. All of the rubber ones (surrounded by a spring) look pretty new, free from any damage and metal parts bright and shiny, and the PO records show a replacement of the brake hoses two years ago (with few miles since then) so for the time being I'm going to rule them out, absent further evidence they're bad.

Test drive went fine. Took it up to the canyons and did a little hard riding, freely using the brakes reasonably heavy. All normal. When on the straights it had no tendency to drift to right. Came back and no smoke or odd smells. (Though previous occurence probably had a little glazing that had to scrub off.) Sweet.

I'm guessing there was something intermittent interferring with the caliper's release resulting in a residual (low level) amount of pressure between the pads and disc. That something now seems to be relieved. I'll keep a watch on it. Any future occurence, or when the pads get low and it's time for front brakes anyways, I'll have the calipers rebuilt and the entire system flushed.

[maurice]

I had the same problem with Sprite calipers on a Morris Minor. The pistons were not returning fully in the caliper bores. I could see black marks on the piston OD's left by the seals. A touch of 'brake assembly lube' on the pistons solved the problem.

[Joe D]

Your front brake lines have swelled up, and is acting as a one way valve.
When you brake the line allows fluid into the calipher but out.
This causes the constant pressure your are feeling, and the over heating your observed.

Replace your brake flex lines and the problem will be solved!

All the best,

Joe

[HealeyBN7]

Joe,

I noticed that you show a Maseratti 3500 in your signature line. Is this the beautiful ice blue car I saw at Motor4Toys?

Tell us more!!

viewtopic.php?f=2&t=158&start=250" onclick="window.open(this.href);return false;

Dean

Your front brake lines have swelled up, and is acting as a one way valve.
When you brake the line allows fluid into the calipher but out.
This causes the constant pressure your are feeling, and the over heating your observed.

Replace your brake flex lines and the problem will be solved!

All the best,

Joe

[Joe D]

Dear Dean,

Yes, that was my car. I finally finished a full restoration on it last year, and have been driving it arround.

I have owned it since 1984, and do all the mechanical work on it myself.

I hope to participate with the events of the group now that I know about you guys.

Regards,

Joe


[quote="HealeyBN7"]Joe,

I noticed that you show a Maseratti 3500 in your signature line. Is this the beautiful ice blue car I saw at Motor4Toys?

Tell us more!!

viewtopic.php?f=2&t=158&start=250" onclick="window.open(this.href);return false;

Dean