Tires Squel When I Brake - Why?

[Gregski]

Got three dirt old Copper Trendsetters SE 235/75 R15 tires on my '74 1/2 ton GMC 350 manual and one brand new one of the same kind in the rear.

When I brake and it can be at very low speeds (10 to 15 MPH) or even slower as I come to a stop sign or stop light the tires squel it sounds as if I am peeling out.

I am gentle on the brakes as gentle as I can be.

Any idea what this could be? Old tires? Brakes locking up since they are not anti-lock? Driver not knowing how to brake properly? Etc.

[Jake Wade]

Is it actually a squeal from tire rubber skidding on the pavement? or is it a brake squeal?

[bigblock73]

Sounds like a wheel is locking up. Check your wheel cylinder to see if it is leaking fluid on the shoes...this will cause that wheel to lock up extremely easy with minimal pedal pressure.

[Gregski]

Originally Posted by Jake Wade

Is it actually a squeal from tire rubber skidding on the pavement? or is it a brake squeal?

thanks Jake, sounds like rubber on pavement

[Gregski]

Originally Posted by bigblock73

Sounds like a wheel is locking up. Check your wheel cylinder to see if it is leaking fluid on the shoes...this will cause that wheel to lock up extremely easy with minimal pedal pressure.

Thanks Jeff, it sounds like its coming from the front wheels, and I got disc brakes in the front, would that still be the case with a leaky cylinder in the front?

[buddy_1]

Sounds like the rotors are glazed causing a brake squeal. Rule of thumb is if they squeal all the time and it goes away when you brake, it the brake wear indicators. If it only squeals when braking, it is the pads or rotors are glazed. Have you had someone watch as you do it to see if the tire is actually sliding? Have you noticed any pulsation or rocking sensation while braking?

[Dead Parrot]

Had a set of tires years ago that did that. They would squeal like a panic stop even during normal braking. Was really bad on asphalt. Don't remember the brand. When I replaced the tires, noise went away.

[Gregski]

Originally Posted by Dead Parrot

Had a set of tires years ago that did that. They would squeal like a panic stop even during normal braking. Was really bad on asphalt. Don't remember the brand. When I replaced the tires, noise went away.

My thoughts exactly, thank you DP, now the dilemma is do I move the new 235/75R15 tire from the rear to the front and buy a matching new one for the other side. Or do I punt on the child's play 235s and take this opportunity to put some 275/60s meat on the bone? By the way we are running 8" rims.

[Gregski]

Originally Posted by bigblock73

Sounds like a wheel is locking up. Check your wheel cylinder to see if it is leaking fluid on the shoes...this will cause that wheel to lock up extremely easy with minimal pedal pressure.

Well shoot Jeff, you were right I applied the brakes with two buddies looking at the wheels and sure enuff my rear right wheel is locking up. It is the only wheel doing that, so it's the passenger rear tire making all that noise.

The plan is to switch wheels tonight and see if the problem follows that wheel (old tire) or if it stays with the drum brake. Again I only have one new tire on the back driver side. I plan on replacing the wheel cylinder or both rears tonight depending on my findings. I also ordered another matching new tire so that both rears will be new.

[bigblock73]

Originally Posted by Gregski

Well shoot Jeff, you were right I applied the brakes with two buddies looking at the wheels and sure enuff my rear right wheel is locking up. It is the only wheel doing that, so it's the passenger rear tire making all that noise.

The plan is to switch wheels tonight and see if the problem follows that wheel (old tire) or if it stays with the drum brake. Again I only have one new tire on the back driver side. I plan on replacing the wheel cylinder or both rears tonight depending on my findings. I also ordered another matching new tire so that both rears will be new.

Sounds like a good plan...report back your findings.

[Gregski]

Originally Posted by bigblock73

Sounds like a good plan...report back your findings.

After I switched the rear wheels: left <=> right the problem stayed on the passenger side with the drum brake

so it was time to buy new wheel cylinders, I bought two since they were only $9 bucks each, and replaced both sides

with new cylinders installed and brakes bleed = Problem Solved

You can see the rest of the progress on my build thread Restoring Rusty

[bigblock73]

Rock on, thanks for the update!

[Gregski]

Originally Posted by Gregski

... so it was time to buy new wheel cylinders, I bought two since they were only $9 bucks each, and replaced both sides

with new cylinders installed and brakes bleed = Problem Solved

I would like to withdraw that statement as I may have celebrated too early. So I still have the same problem. So back to the drawing board

[buddy_1]

Did you replace the brake shoes with the wheel cylinders?
The side that was leaking is saturated with fluid that will cause the brakes to lock up.
Replace the shoes and clean the drums and backing plates with denatured alchohol or brake cleaner. Buddy

[77 350 Shorty Wide]

Buddy_1 has the answer to your problem. Getting brake fluid on the shoes will surely cause this kind of problem. New shoes and either replacing the drums with new or doing a super cleaning job should cure the problem.

Bod bless, Terry

[Gregski]

Originally Posted by buddy_1

Did you replace the brake shoes with the wheel cylinders?

No I did not.

Originally Posted by buddy_1

The side that was leaking is saturated with fluid that will cause the brakes to lock up. Replace the shoes and clean the drums and backing plates with denatured alchohol or brake cleaner. Buddy

Thank you very much, that is sound advice, I will do just that this weekend. I am a bit hesitant with replacing the shoes without replacing the drums or at least turning them, that was one of the things my daddy taught me, so we'll see how that goes. Thanks again

[tucsonjwt]

I saw a youtube video where a fellow cleaned off brake shoes saturated with brake fluid and made them work. I would give it a try if I had the problem - in the interest of science - but most will tell you that it does not work.

[Gregski]

when I take apart the entire ensemble I will look to see if anything could be binding

I am curious if swapping the guts from one side to the other and the drums would be worth it in terms of troubleshooting, would it be safe if I kept the shoes and drums together?

I really don't like to just throw money at the problem to fix it instead of understanding and seeing what the actual specific problem is, you all know what I'm trying to say?

[nonstop]

Brake shoes are cheap and it would be a worthwhile investment. You replaced the cylinders and that didn't fix it. Do the shoes and even put in a hardware kit to make sure everything is working right.

[badchevy]

I'm having the same problem with my '87. I replaced both brake cylinders and shoes and still locks up. This only happens when I first drive it. After braking several times, all is good. Only thing I haven't done is replace or turn the drums. I also bled the brakes several times thinking there was air in the lines.

[Gregski]

OK, so decided to take off the drum and take a look, and when I did this fell out, I call it the shoe spreader, not sure what it is called

I guess this would explain at least why initially I thought the problem was fixed, it probably worked fine till this somehow fell out then the wheel started locking up again

anyway I put it in all nice and proper this time and wanted to take the truck for a test drive, but the darn thing won't start, now I don't want to get off on that tangent but I will tell you I just bought a new battery and hope to put it in tomorrow and report back to you

[cadillac_al]

Originally Posted by badchevy

I'm having the same problem with my '87. I replaced both brake cylinders and shoes and still locks up. This only happens when I first drive it. After braking several times, all is good. Only thing I haven't done is replace or turn the drums. I also bled the brakes several times thinking there was air in the lines.

It may be the axle seal then. I have had one leaking on my convertible for over 5 years. It locks up on the first few stops then it clears up. It's fun as hell scaring jaywalkers with a nice screeching low speed lockup.

[badchevy]

Originally Posted by cadillac_al

It may be the axle seal then. I have had one leaking on my convertible for over 5 years. It locks up on the first few stops then it clears up. It's fun as hell scaring jaywalkers with a nice screeching low speed lockup.

Axle seal is not leaking. I'm going to take the drums off and get them turned. Hope that solves the problem.

[LeesTruk]

Check to see if your e-brake cable is "frozen" to the offending side. You should be able to actually pull the main cable and hear the e-brakes expand/contract on both sides if your cables are good

Lee

[badchevy]

The park brake is good and not binding. I did tear it apart again today to find a cracked brake shoe. I replaced both sides again and also had the drums turned. I'll find out tomorrow morning if all is good.