: Grabby rear brakes???



N0DIH
01-17-06, 06:57 PM
Ok, I have been fighting with my rear brakes for a few weeks now. I have done several sets over the years and this one has been the most pain!

I put on new shoes, and the previous owner or shop, had put on the leading/trailing shoes on the driver's side reversed. Ok, when I put on the new ones, I did the same, just simply copying what they did. Oops on me. It was grabby and kicking in ABS WAAAAY easy. So I fixed it. But the problem was the brakes didn't release very well and overheated and warped the drum pretty bad. I did also have to go back in and replace a leaking wheel cyl.

So I bought and installed new drums yesterday. At first they were great, good feel, solid braking. But as I am driving it to work and back (I am up to 60 miles on the new drums) it is getting grabbier and grabbier. And now the left side is starting to squeal. I didn't notice anything wrong with the shoes, but I am starting to wonder if they are messed up and now need to be replaced?

New springs, shoes, one left wheel cyl and drums, and I am having fits with it feeling like it is dragging slightly and the left side running warmer than the right. Almost like the adjuster is overadjusting or something.

Is there anything I could have done wrong with bleeding the brakes? I have seen a bad combination valve make the brakes on a 76 250 6 cyl Cutlass that would lock up all 4 at any speed with light brake pressure.

Any thoughts on something I am missing?

The springs all look ok and in the right places (hard to mess up that), short shoes on front, long on back (as per 1976 Olds FSM), new drums now, but the left side is getting warmer than it should I think, as well at start to squeal, which is something I have never heard a rear drum do. Almost like I am fighting a lot of contamination.

ocjmakaveli
01-17-06, 08:29 PM
i cant say for certain on the fleetwoods but I had a similar problem once and it was the parking brake springs were weak causing the brake to apply by itself.

I'm leaning towards a spring issue on that wheel causing the pads not to retract properly.

N0DIH
01-17-06, 08:37 PM
Which springs? The one under the dash or at the wheel?

N0DIH
01-17-06, 11:14 PM
Well, after the drive home and stopping by an Autozone, they thought it might have been glazed somehow.

Once I did a few hard stops it seemed to clear up and get back to normal.

I was thinking, they put that coating on the drums to protect them from rusting, and I have always cleaned that off, but this time I was in a hurry and I didn't. I suspect it got hot and gooed up the drums and shoes. A few good stops seemed to clear it up.

Hopefully this is the end of it all. This has been one nightmare brake job!

caddycruiser
01-17-06, 11:22 PM
Not a drums issue, but I noticed that the brakes (most definately the fronts) feel kinda funny on the '95 I just bought. I didn't expect everything to feel exactly like the '93, but while it has about the firmest, crispest pedal feel of any of our cars, the '95s feels almost as firm overall but also is kinda "grindy" if you do anything other than a feather light stop. Feels and sounds almost as if you're stopping with front tires that are low, making the front end a little softer and the brakes both sound & feel like they're scraping/slipping at the same time.

Still stops 95% as well as the '93, but the somewhat odd feel and sound is making me wonder. Visibly, the pads and rotors look completely fine, but still...or maybe it's the different, larger tire tread?

N0DIH
01-17-06, 11:28 PM
Actually the way it has been feeling all this time is like it had 50% rear braking power. Sorta annoying as anytime I would get into the brakes slightly hard it would lockup and the ABS would kick in trying to keep it from locking up.

But when I was braking normal to light, it felt great.

Seems much better now. Much much better.

ocjmakaveli
01-18-06, 12:35 AM
the parking brake would be a drum spring issue

Sometimes not sure if this is what happened in your case the kits have all the springs except the parkine brake springs and those get old and the brake starts to apply on its own.

Or if a spring fell off etc. that could cause it too

You did turn/cut the drums right? I would highly recommend that always and always :D

It could have just been a case of the new pads having coating on them causing that lockup. I changed the drums on a minivan early last year and I had a few lockups the first 5 miles i drove it but not too bad and it went away.

N0DIH
01-18-06, 12:45 AM
I rarely turn the drums or rotors unless they are actually out of round. If they are grooved a but, I don't. They will wear out in a short time. GM even specifies that for grooves not to turn unless they are deeper than xx inches. I think around 0.050 to 0.100" inches. I have had around 0.150" grooves from rivets in my rear drums and in 15K miles they were gone.

Drums these days are way too thin to turn everytime you do brakes. Then they warp even faster.

I do supsect it was the coating that gummed it up. One was coated more than the other. I'll know better tomorrow how it is doing.

I had pondered doing a 12x2 brake drum swap, but looking at Autozone, those drums are getting scarce. They are in a EOL and do not source new ones. So you 76 and older Cad owners that have the large 12x2 brakes, order your drums now or find a source. And they are $82 each and must be ordered.

ChiTDI
01-18-06, 09:22 AM
Nodih- The return springs are a likely candidate for a grabbing brake, the gummed material on the shoe will do it, as well as brake fluid that may have leaked from the wheel cylinder. Although the symptom then would be chatter. Does it stop well now or does the issue remain?

N0DIH
01-18-06, 08:44 PM
did the hard braking last night 3 times in a row (don't want to get it too hot) from 65 to 15 or so. Gave it a few miles in between. Seems pretty good now. Solid in back, started a little itty bitty squeal this morning, but since seems ok the rest of the way to work. Only 1 harder stop today and it was fine.

They seem to release ok, but seemed like they were just very close between the drum and the shoes when it would get warm. I guess thinks expand some when hot.

N0DIH
01-20-06, 07:40 PM
Well it still is wanting to squeal some. It sure feels like the left rear brake is activating sooner or has a lot more power than the rest the brakes on the car, causing it to work much much harder. Everytime I stop that one is very hot. The rest only somewhat hot. It isn't dragging, I can coast fine.

I changed the wheel cyl on that one. So it got bled and all. I know on my G-Body cutlass there was a button you had to press to do something in the combination valve to allow for proper bleeding. I did press on the brake pedal gently before I put the drums on with the old wheel cyl, I just had to push the brakes back in, as it didn't fully retract.

Did I screw something up when I did that? I bled it a lot when I did the wheel cyl. So i am confident on the lack of air in the lines. I did NOT bleed the pass side, only driver. As I only took out that wheel cyl and we have 4 brake lines, and it was plugged when it was disc, it shouldn't be a problem, should it?

I am starting to get pretty crabby over this brake job!

N0DIH
01-21-06, 07:14 PM
Anyone??

The Ape Man
01-21-06, 10:38 PM
Yeah, I'll take a shot. Bleed the other side. Get a propane torch to heat the bleeder screw if you are worried about snapping it. Watch the brake fluid because it can light off going through a hot bleeder. Squeeling on drum brakes is usually a sign of something that has popped apart and is getting ground to death. Double check the parking brake cable to make sure it isn't binding. Are those the same shoes that were on backwards?
What preceedure do you use for star wheel adjustment?

N0DIH
01-22-06, 01:02 AM
I'll give it a shot tomorrow. Yes, they are the same shoes. I am wondering if they just got beat up too much. The brake feel is great, but you can tell it is heavily biased rear. And when you go to hit the brakes hard you can feel the left rear ABS kick in momentarily.

I just adjust the star wheel enough that I can just get the drum on easily. Not cranked up against the drum.

Abused shoes is one of the GM FSM possibilities. They didn't look bad, but I don't know what it would take to be bad at this point.

I was pouring over the FSM today, nothing really jumped out at me. But all stuff in the FSM seems to point towards something with the shoes or some thing hardware is loose. Nothing was looking wrong when I had the drum off (install new drums, and I replaced the star adjuster spring just because the new one I put on seemed to interfere with the star moving. So I put a new one on.

I think first I will replace the shoes on that side and bleed them and see what it comes up with. Man I am getting frustrated with this.....

Oh, the squealing isn't metal on metal, it sounds like one of the shoes is vibrating around 800 Hz or so.


Yeah, I'll take a shot. Bleed the other side. Get a propane torch to heat the bleeder screw if you are worried about snapping it. Watch the brake fluid because it can light off going through a hot bleeder. Squeeling on drum brakes is usually a sign of something that has popped apart and is getting ground to death. Double check the parking brake cable to make sure it isn't binding. Are those the same shoes that were on backwards?
What preceedure do you use for star wheel adjustment?

The Ape Man
01-22-06, 01:42 AM
Shoot it with Mr. camera and post the pix if it still misbehaves.

N0DIH
01-22-06, 02:46 AM
Will do, I almost did when I put on the new drums, but being nothing looked amis, I figured why bother.... Well, it is still a problem!

N0DIH
01-22-06, 06:30 PM
Ok, just pulled the drum on the offending side. There is some rougher than normal abraision on the rear shoe, and the front shoe looks like it has been pretty hot.

I cleaned it all down, sanded all the offending material off the shoes so all surfaces were equal in roughness. Sanded down the drums to a light resurface and I am about to head out on my test drive (100 miles round trip...)

N0DIH
01-22-06, 11:45 PM
Well, once I started using the brakes much, the left rear got hot and still is overachieving.

Time to bleed the rear brakes. I took some picts, I will piston them in a bit here once I get them resized or FTP them to my home page and link them.

When cold they feel good, best pedal you will ever feel, even better than a Hydroboost. But, there is a reason... Something is wrong.

I am wondering if I got some sort of air bubble in the line that made its way to the ABS controller, and then got in the other side, so this one is doing too much work and the other isn't. But you would think it would still try to balance some. But that is a long shot too.

Bleeding time....

N0DIH
01-23-06, 01:28 AM
Here are some picts. They may look glazed, but that is just the tons of dust....

They cleaned up real nice with some sandpaper on the shoe surface.

Anyone see anything I might have assembled wrong?

ocjmakaveli
01-23-06, 03:49 AM
hmm

ocjmakaveli
01-23-06, 05:03 AM
according to the fsm pic the way nodih has it looks correct if anyone can say for sure whether it is correct or not? I'm not quite sure....

The Ape Man
01-23-06, 05:39 AM
Looks OK except the return springs both look like the shoes MAYBE aren't quite returned all the way. Are the half moon cutouts in the tops of the shoes resting against the round gizmo in back of where the LH spring is anchored?

JTraik
01-23-06, 12:08 PM
Did we rule out a sticky wheel cylinder on the offending side? That could be a very likely culprit. Everything looks connected correctly. Have you made sure that star wheel assembly operates smoothly?

N0DIH
01-23-06, 02:51 PM
Yup, it is a new wheel cyl. It did it before and after, the wheel cyl was leaking if you pulled the things out the plunger that go to the shoes.

It isn't that they are dragging. They are grabbing. The FSM lists it as "Excessive Brake Action". But nothing it to reference seems to help. I haven't replaced shoes yet, but I don't think that is it, they are not contaminated, I can clean them up fine, they just seem to be brake happy on the left rear only.

I hope to get time to bleed the right rear tonight. It was never touched, but I am starting to wonder if that is the problem side, and with the ABS controller there, if some air made it there, might have weakened the right side, even though it was left alone (other than new shoes, it seems to be braking properly, not excessive, just normal feel. Wear is normal.)

Everything returns back fine, I can coast well in this car. If I had a draggy brake, it would not coast.

N0DIH
01-24-06, 06:13 PM
Well, I think the ordeal is finally done....

I bled the controller (note, GM gets $1700 for this!! DO NOT break it!!), and both rear brakes.

I suspect the FSM saying that you only need to bleed the brake line that got air in it is meant for the front, not the rear. I am guessing something got out of balance or a check valve stuck or ???

I did several repeated hard stops and some city type driving just to get them hot, some 70+ to 10 stops, and no problems whatsoever. Drum temps (left side) are 80% cooler. Before I could not even touch the rim after driving, no I can and it is just warm, and braking is very good to excellent.

Thanks for the help! I hope no one else has this nightmare...

ocjmakaveli
01-24-06, 06:21 PM
you bled the abs?

N0DIH
01-24-06, 06:35 PM
Yup, there is a bleeder on it that you open and connect a hose to and let it gravity bleed. Pressing the brake pedal does nothing with this open. You let it bleed and it will slowly drain the master cyl resovoir.

The Ape Man
01-24-06, 07:06 PM
Stop reading so many FSM's. Some are CYA for engineers and not much more.:)

JTraik
01-25-06, 12:04 PM
I was poking around the ImpalaSSforums and I found someone with your exact problem, I almost told him how to fix it LOL! :p

I wonder if this feature is on the '93 units?? Ill have to check.

N0DIH
01-25-06, 12:12 PM
I do have a post there too, is it me? I am RamAirRocket on there, as that was my old screename with the Olds stuff. Look in the Olds FAQ's, lots of us are all over that.

It is if it has the the 4 Channel ABS, I am not sure on 93, but 94-96 it is.

JTraik
01-25-06, 03:31 PM
I do have a post there too, is it me? I am RamAirRocket on there, as that was my old screename with the Olds stuff. Look in the Olds FAQ's, lots of us are all over that.

It is if it has the the 4 Channel ABS, I am not sure on 93, but 94-96 it is.

Yeah it was you! They seem to be much more technical on those forums thats why I like them, although everything is model specific.

I have the 3 channel, still wonder if that bleeder is on there for future reference.

N0DIH
03-19-06, 07:55 PM
Problem is solved!!!

Bad relining of the shoes. The short side pad was starting at the BOTTOM of the shoe, it should be in the middle, centered on the shoe. But it was not relined correctly. I purchased them from Advance Auto Parts in Beloit, WI. Which I am unsure if I will return to them or not, as this is a major safety issue. I'll probably talk with the WI DOT first and see what they want to do. Any car with these made this way will very likely exhibit the problems I have been fighting with, which could cause an accident. If GM did this, they would end up with a recall on their hands, this company should be held the same.

The brakes now work perfectly as GM intended. Lots of nose dive, but the brakes stop you hard if you get on them.

Anyone with a 73-96 A/B/D/G body car with the 11"x2" these brake shoes who keeps them on likely in a panic brake situation and no ABS will be swapping ends very easily.

If you have purchased any rear brake shoes, please inspect them very carefully. Ensure the new replacement lining is exactly how the previous one was designed.

Now I know why I have been pulling out my hair on this problem! Told you I wasn 't crazy guys!

ocjmakaveli
03-20-06, 01:16 AM
Concerning the last post I would say instead of relying on abs to kick in why not stiffen the front suspension to lessen nose-dive, buy better tires for better traction===less lock-up and lastly learn to brake under panic stops you can always feel when the brakes are going to lose grip.

Of course the best setup would be rear discs for a more even braking system and a slightly harder front suspension to avoid too much weight transfer.

N0DIH
03-20-06, 12:34 PM
The interesting thing is I put these brakes on around early Jan/late Dec. And they are worn down over 50% in only around 8K miles! That is how hard they were working over the front.

Not so much adding rear power, although it felt great, when you get on it, it was a major problem. I have always wanted to do sort of a front/rear antisway bar, something that when the front would dive, or the rear would lift, it would be like the front sway bar we have now that balances left/right to balance nose dive and allow the rear brakes to work. But it would ride goofy and not work as it sounds....

Now when I am hard on the brakes, it takes a large bump or something in the time I am braking to hop the back end to kick in ABS or something slick, else it works well now. Which is normal.