Strange braking problem

I have a 72 roadster, in great shape, daily driver. I'm driving home today and feel a funny pulsating feeling when I apply the brakes, sort of like there's a bad spot on the tires but only when I apply the brakes. It was very noticeable. As I got closer to home it seemed to get worse. I applied the brakes very firmly and the car pulled to the left noticeably. The next time I applied the brakes they locked up, causing the tires to slide. As I approached home I had to gently apply the brakes to keep from locking up...very strange.

I have new tires and the car drives smooth and straight. I checked under the car and found no sign of fluid...actually my B doesn't drip or drop anything...I know....strange for a Brithish car.

Any ideas? My good British car mechanic is 30 miles away and I don't think its safe to drive that distance.

Can a good general mechanic/brake shop handle the brakes on an MGB or must I go to a specialty British car place?

Advice and thoughts appreciated!

Thanks,

David

In the library section there's a troubleshooting guide with an extensive section on brakes, this should help, at least you'll know what you're dealing with. Good Luck, Mike

It almost sounds like a warped rotor. Could be a wheel "misallignment" when the new tires were put on the car, such as a lug bolt/nut not seated properly. One more suggestion a loose caliper or debris in the brake pad. Let us know, Mike

Will do

A reputable brake shop should be able to correctly diagnose your problem, brake systems of this age are, for the most part, very close in form and function.

[quote=RMikeM]

It almost sounds like a warped rotor.[/quote]

Agreed.

David - I had symptoms similar to what you've experienced (sans the brakes locking up) evident on my old Chevrolet K1500 and my Suzuki motorcycle. The truck's front rotors needed turned (and eventually replaced -- thanks, AC Delco) and the bike's front disc needed replaced outright. The work was straightforward enough. George P is correct when he suggests that modern braking systems -- even the ones found on our Bs -- are relatively universal in design and function.

-Jim

David, I would check out the braking system first. Obviously you have a problem that needs to be remidied.

Do you know if its the front or rear locking up? Go there first and examine the problem wheel.

Excessive heat from a dragging caliper/stuck piston or collapsed brake hose may cause a rotor to warp.

It's not a difficult job to replace rotors and pads and it will save you a ton of $$$.

If its the rear, remove drum, check to see if all springs are correct and handbrake actuator is releasing and

there is no grease or fluid on the shoes.

RS

I might say a brake hose was collapsing not letting your calipers release thus the lockup. There's not a lot of run out these rotors can handle so it's reasy to warp them. Jack the car a see how much drag you have on the left wheel. The collapsing hose though is hard to see. Since you'll be into brake work it doesn't cost much to change all three hoses.

The hoses swell closed from age. You will not be able to see that the hoses are bad, but if they are more than 7 - 10 years old they NEED to be replaced (all three). That's most likely what made the wheel lock up, but even if it's not, they need to be replaced if they are old. The pulsing sounds like a warped rotor, which could be because of the bad hose which would cause the piston to retain pressure on the pad, heating up the rotor and warping it.

Hee Haa two votes for brake hoses. There is a test I got from another site. Jack the car and apply the brakes hopefully locking the caliper. Spin the wheel to see. Release the brake and loosen the bleed nut. If the fluid pressure is trapped between the caliper and the hose from a collaped hose you should get a spert of brake fluid from the bleed nut and the wheel should releases.

Brake hose problems and bad discs don't happen as quickly or progress as quickly as you described.

Jack up the car, grasp each wheel at 12 and 6 and wriggle. Focus on the wheel that locked up. There should be no appreciable slop between the wheel and the suspension.

Dollars to doughnuts you have some bad wheel bearings. If so service BOTH sides of the car.

Something as bad as you say it is must be addressed immediately. No driving, no nothing. Either fix it where it sits or have it delivered to someone.

Jack

Although jack may well be correct in diagnosing bad wheel bearings, a bad hose and warped rotor actually can occur without notice.

If the hoses are old and swollen (all old hoses swell with time...it's just the nature of the beast) and the system hasn't been completely flushed in years (very likely if your hoses are old enough to be swollen) then what's left of that tiny opening in the old hose can easily clog with debris without warning. And if it locks up the caliper tight enough to heat the rotor up, after a few miles it will warp, especially if the outside temperature is a bit cold or if you ride through water while it's locked up...which is what happened to me 30 years ago. The rotors on B's are pretty thin to begin with. Warping them is easy if you don't look after your entire system.

Like I said, Jack may be correct, but if you have ANY doubt as to when the last time your hoses were replaced, do it now. Do not take chances with a brake issue. ANY brake issue.

I can see what Jack is saying too but the reason I said hoses is that the left locked when you applied the brakes. If a bearing was bad you would hear a feel something in the front end all the time not just when you apply the brakes.

All good suggestions. If it where me I'd change hoses anyway which mean a complete bleed. Repair or replace the rotors both sides which will need pads too. Pull the wheel bearing and check for any damage or bluing than fix and repack. If all is well with them fine, new grease can't hurt. Don't remeber if the wheel bearings have end float on a 72 and always use a good torque wrench.