locking caliper and ABS problems

Petey

Well-Known Member
I just got back from a weekend trip to NH and my truck must not have wanted to go because it had a tough time.

90% of the time when I stopped the ABS would engage.

This afternoon I jacked it up and found some play in the left front hub (well I assume it was the hub because I didn't see any movement in the BJ or Tie-rods) it was there at 3 and 9 or 12 and 6.

I have a Timkin on there with 45K/ 6 years on it but its still quite just lose. OEMs just growled at 65K. Should I go for another Timkin or is there a better one?


Problem 2

In traffic on the way home left from brake locked up on me. I got it to the shoulder (smoking), I waited A min there deciding where to have it towed to and just put it back in gear and it started rolling on its own. I got it to the next rest area and both brakes where same temp (normal). We made it home no problems after that. After the remaining 200 miles left rotor temped at 150 right 118.

Left front wheel has a lot of brake dust on it, right is a lot less but still more than normal. The calipers retract easily when pushed back in, the pads float free, so I am looking at collapsing hose(s) Thoughts?
 

gmcman

Well-Known Member
Hard to say but I would think either a sticking caliper and/or a collapsed brake hose. The brake hose will look fine on the outside but will have broken down on the inside.

If you can raise the front wheel off the ground and grab the tire at 12 & 6 O'clock and feel it rock back and forth then yes, I would replace it sooner than later....may also sound like a mud tire going down the road.

To check the lower ball joint, you need to raise the tire off the ground about an inch or 2 by the lower control arm,.not the frame
.. keeping the suspension loaded,

Then using a pry bar, under the tire, try to lift the tire observing the lower ball joint. If the lower ball joint has up and down movement then it needs to be replaced
 

MRRSM

Lifetime VIP Supporter
It strikes me that these Two Problems (Yup ...and throw in the ABS as reacting to these first two issues) are basically happening Hand-In-Glove with each other.

Think About it...

(1) With the Timken Bearings (reputations aside) allowing enough 12 O'clock <-> 6 O'clock TILTING... it is important to remember that the Caliper Brackets surrounding the Discs are essentially Held in a Rigid, Solid State Condition ...and immovable for all intents and purposes, while the Outer Orbit of the "Spinning Brake Disc Platter" was (is) Loose as a Goose...and free to react to the motions of the Truck moving laterally ...Left and Right and wobble from the 12-6 Positions. This action would allow the Disk to make Frequent Hard Contact with the ostensibly "relaxed" calipers and Brake Pads at the Very Top Edges... and the unintended, constant friction between the two would serve to Very Rapidly Heat up the Brake Disc Platter to nice, warm...Cherry Red.

(2) But once you replace the Left and Right Wheel Axle Bearings-Hubs... as soon as you slip on the Platter and the Wheel and Torque Down the Lug Nuts to Spec.... that "Rocking Action" will immediately disappear. Then the Outer edge of the Brake Disc will no longer be able to make any more "incidental contact" and that translates to mean... No More Unintended Brake Disc-to-Pad Friction--> and No More Heat....unless you have to suddenly Brake Hard or for an extended period of time. So... New Wheel Hubs = No More Thermal Overload from the Brake Disk Contact Problem. One New Timken Wheel Hub "Stone" = Two Dead Birds.

(3) As for the weird problem with the ABS reacting as you were approaching a stopping point... It was probably caused by the unintended contact between the "Wobbly Disc" and the Inner Brake Pad... constantly pushing up against that Brake Pad and applying pressure to the Brake Cylinder behind it (even without your foot touching the Brake Pedal). By doing so... it was probably sending oscillations through the Brake Fluid inside the Brake Line right back to the ABS unit and causing the the ABS Fault Code in response. So... One New Timken Wheel Hub "Stone" just might = THREE Dead Birds. :>)
 
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Petey

Well-Known Member
It had very little movement when grabbed 12-6 or 3-9 but there is a click. No vibrations at any speed.

Is it Timkin's M.O. to just loosen but not growl. Same thing happened on my Saturn twice.

I know the brake locked because it took a lot of peddle to get the truck to move.
 

16vcabman

Well-Known Member
If you have movement in the hub at 12 and 6 o'clock then bearing is bad. All else is moot until bearing is replaced. After the bearing, and if the brake problem comes back then deduce from there. I think bearing is probably the main problem.
 

gmcman

Well-Known Member
If you have movement in the hub at 12 and 6 o'clock then bearing is bad. All else is moot until bearing is replaced.
I agree. Both times my front hub and bearings went bad, I could hear the growl but could not get the hub to move when holding at 12&6...if you have movement then that's definitely time to replace them.

I had about 130K on my OE hubs, then replaced them again at 260K with Timken. I would think you could get more life out of them, unless you may brush up against a curb or 2 pretty hard. Not assuming anything, but it if the wheels have hit a stationary object pretty hard then they can get damaged fairly easily due to the heft of these vehicles.
 
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Petey

Well-Known Member
No curb hits at all and I avoid potholes etc, but I'm sure I got one at some point.


Oe hubs went 60-70k. Truck now has 108k. It is used weekends, trips, and winter driving.

I know the abs problem is the hub, but locking up brake(s)? I'm getting the hub from rock, so I'll just add on the hoses.

Erroneous data from Front abs sensors wouldn't cause the traction control to engage after backing going to drive would it?
 

gmcman

Well-Known Member
I would try to compress your calipers first, see if they are binding. The brake hoses can be stubborn...make sure the brake line doesn’t turn with the nut.
 
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Petey

Well-Known Member
I would try to compress your calipers first, see if they are binding. The brake hoses can be stubborn...make sure the brake line doesn’t turn with the nut.
The calipers compressed easily and slid on the pins, the pads floated in the bracket. I eyeballed the union at the mounting point it looked to be clean and not seized, but I have not tried to see if they move.

I'm just confused as to why it would stick enough to have a major drag on the truck, cause smoking, and a blue rotor (only drove 10th of mile at 25, if that, to get over to the right), then release on its own in 2 min and not do it again for 200 miles. I'm thinking the hose collapsed from the heat (90 temp and slow moving traffic for 5 miles.

On the other hand I have been noticing a bit more brake dust so it has been slightly dragging.
 
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Redbeard

Well-Known Member
How much of the pads are left? I ask because several times I have seen when the pads have been about 2/3 worn down (or more) the piston in the caliper starts go "crooked" and then won't retract properly when pressure has been released (foot taken off the brake pedal that is). Hence the excessive drag. It is most noticeable when I have used a large c-clamp to re-seat the piston to the bottom of the caliper when getting them ready for new pads and it takes excessive force to get the piston aligned properly. After it is aligned properly it always nicely presses back down to the bottom most position nicely without excessive force that is. I wonder when the pads are getting worn out if the piston isn't being staying true to the bore and just going "crooked" and causing all this grief. There is less of the piston in the bore to keep it straight as when the pads are new.
 
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Petey

Well-Known Member
How much of the pads are left? I ask because several times I have seen when the pads have been about 2/3 worn down (or more) the piston in the caliper starts go "crooked" and then won't retract properly when pressure has been released (foot taken off the brake pedal that is). Hence the excessive drag. It is most noticeable when I have used a large c-clamp to re-seat the piston to the bottom of the caliper when getting them ready for new pads and it takes excessive force to get the piston aligned properly. After it is aligned properly it always nicely presses back down to the bottom most position nicely without excessive force that is. I wonder when the pads are getting worn out if the piston isn't being staying true to the bore and just going "crooked" and causing all this grief. There is less of the piston in the bore to keep it straight as when the pads are new.
1/2 to 1/4 left on the pad

I had to replace a rear caliper for that reason. No matter what I did could not get it all the back in (the last 1/8 fought me and won as it was 20 degrees F out at night when I did that job)
 

gmcman

Well-Known Member
Also if your hub and bearing has play like you stated, then the rotor will not run true to the pad surface. This will be a very small deflection if measurable.

I would start with two new hub and bearing assemblies and go from there. If one is worn, replace both.
 

Mektek

Well-Known Member
GM used plastic pistons on the front. When I replaced the pads they dragged. When I installed a repair kit they still dragged. The cure was to install new pistons. It seems the plastic expands slightly with age and that makes them too tight in the seal.
If I knew it was so much trouble I might have bought rebuilt calipers instead of doing all that work....
No such issue with the rear - metal pistons there.
 

xavierny25

Well-Known Member
GM used plastic pistons on the front. When I replaced the pads they dragged. When I installed a repair kit they still dragged. The cure was to install new pistons. It seems the plastic expands slightly with age and that makes them too tight in the seal.
If I knew it was so much trouble I might have bought rebuilt calipers instead of doing all that work....
No such issue with the rear - metal pistons there.
Just wanted to add a tidbit of info to your post. After having fully rebuilt two sets of front and rear calipers for both the the Envoy and TBSS I don't believe the piston are actually plastic but more a composite material. I do however have to say that they do get pretty out of shape over the years.
20190104_112752.jpg
20190109_175701.jpg
20190216_160629.jpg
 

Mektek

Well-Known Member
OMG! pink calipers! :weird: that will cause piston cracking and whining, moaning and squealing! :satan:

I used different Centric pistons (145.45006) that have a steel ring embedded on the top - probably to prevent the kind of damage seen on your pistons. The OEM pistons had no visible deterioration, but had expanded just enough to cause sticking.

They are Phenolic resin/plastic. Similar to bakelite invented a hundred years ago but using nylon or fiberglass fabric. After molding they are machined on a lathe to the exact diameter. Precision is critical - too big and it will cause sticking - too small and there will be leaks.
 

xavierny25

Well-Known Member
OMG! pink calipers! :weird: that will cause piston cracking and whining, moaning and squealing! :satan:

I used different Centric pistons (145.45006) that have a steel ring embedded on the top - probably to prevent the kind of damage seen on your pistons. The OEM pistons had no visible deterioration, but had expanded just enough to cause sticking.

They are Phenolic resin/plastic. Similar to bakelite invented a hundred years ago but using nylon or fiberglass fabric. After molding they are machined on a lathe to the exact diameter. Precision is critical - too big and it will cause sticking - too small and there will be leaks.
@Mektek thanks for that part #. I'll save that for the next set of calipers I have powder coated and put back together.

Lol. I wonder what you think will happen when this much stuff is pink under my Envoy. 20190524_205106.jpg
20190517_130217.jpg
20190313_155941.jpg

It's a fun project but it's still not finished
 

TollKeeper

Well-Known Member
Telling you @xavierny25 ... You gotta get that diff cover painted pink too
 

xavierny25

Well-Known Member
Telling you @xavierny25 ... You gotta get that diff cover painted pink too
20190119_171239.jpg

Already got it, but it's for the 4.10 rear end I'm eventually going to put in sometime this year. I also got a set of brake dust shields coated also waiting to be installed.
 

Mektek

Well-Known Member
like most that wear that much hot pink, there will be a lot of bouncing and jiggling in the front and rear end:crackup:
 

TollKeeper

Well-Known Member

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