Are My Brakes Dragging? (videos inside)

[LaurentD]

A While back, I had noticed that, when my car is jacked up, the front wheels still have a lot of resistance to them, caused by the braking system. I decided to shoot some videos of it, hoping I could get SupraMania's opinion on the subject.

Rotor + Caliper + Wheel
Rotor + Caliper
Rotor Only

It might not be easy to tell from the videos, however on the last two, I tried to apply the same force for comparable results. If there is any specs or test that would help to determine if my brakes are dragging excessively, feel free to educate me.

I know brakes are supposed to drag even at rest, but does it look like mine are dragging too much? Before increasing my Supra's power, I would like to make the most out of the power I already have. :icon_bigg So, if you have any ideas on how to minimize energy losses here, please chime in!

Thanks a lot!

 

[radiod]

Make sure your slide pins and pad slide surfaces are all well lubed with brake silicone grease. Make sure you use stuff that's meant for brakes as well, it gets extremely hot in there and you can ignite lubricants that aren't made to be used under such hot conditions. Also, if you have a wheel that's dragging excessively you will notice a pull when driving.

Another way to confirm it is to grip a spoke (or in your case around the back side of the wheel/tire) after a highway cruise and you'll feel a little heat radiating off the brakes. Compare the two wheels' temps and you can usually tell if one side is dragging more than the other. DO NOT TOUCH THE BRAKES OR BRAKE HARDWARE!! They are still hot enough to ruin your day.

 

[Satan]

...how old is the master cylinder? I had to replace one in my 87T and the rebuilt one, caused dragging in the rear wheels. Argued with the auto parts counter people and got a replacement (had lifetime warranty anyways, but they sometimes don't easily take things back). Point being, dragging is when a failing MC is applying pressure to the front, or rear, brake lines/system (both fronts or rears will have the same drag/pressure).

Anyways, if it's been a looong time, it may be a symptom of a tired master cylinder. I'd recommend you already order the rebuild kit and have on hand (I think the kits are less than $20... make sure U use the lube mentioned in the TRSM), or get some quotes/availability for a new or rebuilt one.

Good luck!

 

[LaurentD]

@Radiod
The car doesn't seem to pull at all. I like the radiating heat method to compare wheel drag between left and right wheels. I could even easily rig some thermocouples to read the temp diffence while driving. However that won't tell me if both front wheels are dragging. I'll still try it out though.

@Satan
You seem to suggest that my brakes are in fact dragging excessively? Once I know for sure that they are, then I will look at the causes for it, and what parts to replace/rebuild. As far as I know, my whole brake system could be 24 y/o. I woulnd't mind rebuilding the whole system, if I know that there would be a susbstancial benefit from doing so. MC would be a good start.

Thanks for the input so far!

 

[Poodles]

Second vid, you don't have the rotor bolted to the hub, so they will drag as the rotor goes cockeyed on the hub.

Also, your rotors look glazed to hell...

 

[destrux]

With my car jacked up, if you spin the wheel it will keep spinning for a while, and you can't hear anything dragging or rubbing. The caliper piston seals retract the pistons a few thousandths when you let off the pedal, and then toyota has those two V shaped wire springs that spread the pads a little bit, so there should be no rubbing or dragging. There are a ton of things that can cause it, but the caliper slide pins being rusted, brake pad edge contact surfaces being rusted, clogged brake hoses that only let fluid go one way, stuck caliper pistons, and worn out wheel bearings are the most common things. If those check out, then I'd go after the brake booster and then the master cylinder, but those are fairly uncommon reasons for a brake drag.

If it's an ABS car, a problem with the ABS unit can cause it too.

If it's a fluid control problem (hoses, master cyl, ABS unit, booster) opening the caliper bleeder for a second to release the pressure should make the brake drag go away. That's an easy way to check/rule out those parts.

 

[radiod]

...and then toyota has those two V shaped wire springs that spread the pads a little bit...

Those spring clips make a bigger difference than most people realize. Make sure those are there.

 

[Maple191]

Its possible to have worn out wheel bearings. i just replaced mine. The wheel was dragging, had no play in it but the bearing was grinding. You couldnt feel it grinding until the Rotor was completely off the hub.

 

[LaurentD]

Thanks destrux and all others,

this confirms that it is time for rebuilding my brake system and make it work like new again. I have also found this post with good info, saying that the non-driven wheels shoud be able to do quite a few rotations. After much reading, here is what I am plannig to do for all four wheels:
- Brembo blank Rotors
- Porterfield R4S Pads
- All new pad shims + hardware
- New flexible brake lines (SS maybe)
- Inspect Parking Brake and replace parts as necessary

1) In regards to the wheel bearings, is the TSRM axial play check sufficient to tell me if they are worn out?

2) I want to do something about the calipers. However, I am daily driving the Supra until the end of August. I certainly can't do the whole brake job over a week-end, if I have to rebuild the calipers myself. Should I buy some new oem calipers on Rock Auto, or is it worth it to wait untill September and rebuild my Toyota ones (which are still in very great shape; no rust!)?

3) Is there anything I should do about brake hardlines, except for a good fluid flush? Those wouldn't get clogged, would they?

 

[robawelch]

Rebuilding our stock calipers takes little time to do given you have the tools. Compressed air. Some grease. And your hardware. The whole job can be done in a weekend easily.

 

[robawelch]

And except for head bolts. Follow the TSRM for everything. Why wouldn't you anyways??

 

[LaurentD]

@robawelch

Even though I have never done it, rebuilding calipers does seem very easy to do. I just wouldn't want to risk to have the car not running to get me to work. Also, I'm not perfectly well equiped. I don't have compressed air and do all the work in the driveway. I still managed to rebuild my motor in the driveway lol. But it took me 2 months almost full time. I have never bled brakes before either.

As for the TSRM, It's my bible. However, Maple191 seemed to say that his bearings were worn out even though they had no play to them?

 

[Poodles]

Rebuilding calipers can be a bit fiddly. If there's rust in the slide areas or where the pistons go, it can make rebuilding them a pain. It's more expensive to buy remanned calipers from some place like rockauto, but if it's your daily driver you really don't have the option to be screwing around...

Might want to check your master cylinder as well while you're at it.

 

[Satan]

Rebuilding our stock calipers takes little time to do given you have the tools. Compressed air. Some grease. And your hardware. The whole job can be done in a weekend easily.

I agree... You can do it in an afternoon. Just recently helped a friend who also did not have "brake-bleeding" experience... Took maybe 2 hours for him to do all the calipers (including drying time, 'cause he did want to paint 'em). The MC takes about 30-45 minutes to remove, rebuild, reinstall. I'd help ya, if you were closer

Does go smoother/better with someone else (experienced) that can help. Just ordinary tools and tho maybe you should wait 'til the end of Aug (in case U need to let sit a couple of days), there's a lot of gunk in them lines... I'd do it all at the same time and flush. Be prepared to find that brake fluid is clear... not the brown we're used to seeing in our reservoirs.

 

[Maple191]

Thanks destrux and all others,

1) In regards to the wheel bearings, is the TSRM axial play check sufficient to tell me if they are worn out?

That only determins how much run-out is in the bearing a.k.a free play. And the answer should be zero. But ths does not stop the bearing from grinding, without free play. I know because mine had zero free play but had catastrophic bearing failer. (there was a huge gouge on the inner race, bigger then the ball bearing that was riding on it.)

It was so bad if you were driving anything over 10km/h you whould hear a knocking noise from the front of the car. It honestly sounded like someone was hitting the floor with a hammer.

If I find it I'll take a picture and post it.