13 replies to this topic

[William Bonsell]

After installing new ART front hubs, rotors, calipers and Hawk pads over the winter, I seem to be suffering from consistent pad drag which I did not have last year with old front hubs, bearings, rotors, etc. I use the clips but not the springs...same as last year. But with the front wheels off the ground, they both do not spin nearly as freely as last year before the upgrades. It has been suggested that I need to retain the springs, but I did not use them last year. I know some use neither the springs nor the clips. Is it possible that we torque'd the hubs nuts too much thus causing the tightness? I know in the big scheme of things, it is not going to affect much, but it does bother me and I would like to have as little resistance as possible. Thanks.

-Bill

[Tom Hampton]

Hub nut wouldn't cause PAD DRAG. Are the PADs dragging, or does the wheel just not spin as freely. You should be able to hear the pads drag on the rotor. the caveat with this is that the pads don't get knocked back on the last stop. So, SOME drag is expected. However, I just finished resolving a front drag problem. In the end, I replaced both front calipers AND the master cylinder---each change resolved about "half" of the drag.

From what has been said before, once the wheel nut is torqued beyond 100 ft-lbs or so there is no appreciable difference in drag in the hub.

I don't run the clips OR springs. When I was trying to solve my drag, someone recommended removing them. But, I didn't notice any change in drag when I removed them. I still got the same number of revolutions of the wheels after there removal...from a "calibrated" spin of the tire. Since so many people run without them and don't have issues, I chose not to put them back. Pad changes are certainly easier with those things.

[trey]

Bringing this back from the dead.

I did the full deal : new packed hubs , new rotors , new pads without hardware or springs ... Without the caliper on the wheel spins very free , With the caliper on there is significant drag ... I think , maybe it will free up after a few laps ... No ... So I rebuild the caliper ... Just as much drag as before.

What's next ?
- New calipers ??? Why ???
- New master cylinder ??? Why ???
- Anything I missed ?

[Bench Racer]

Bringing this back from the dead.

I did the full deal : new packed hubs , new rotors , new pads without hardware or springs ... Without the caliper on the wheel spins very free , With the caliper on there is significant drag ... I think , maybe it will free up after a few laps ... No ... So I rebuild the caliper ... Just as much drag as before.

What's next ?
- New calipers ??? Why ???
- New master cylinder ??? Why ???
- Anything I missed ?

Does the piston release the pads so the wheel may spin?

I'll be specific, did you use Permatex synthetic ultra disc brake caliper lub? It's the stuff in the green tube or packet. The non synthetic lube sucks & makes the pins sticky to the rubber bushings.

Without the pads in place did the floating half of the caliper move back & forth freely?

Did you use the caliper inserts? Those shinny little deal-bob's that fit ino the caliper notches where the pads slide.

Did you open up the U shape of the caliper inserts where the pad slides back & forth?

Did you file the internal & external corners of the pad backing plate that hits the wear edges of the caliper inserts? On the internal corners file an undercut if need be.

When you put the pads in place without the seperation springs did the pads float freely before the brake pedal was steped on?

Did you use the caliper separition springs? Replace frequently.

[trey]

Looks like I missed a few opportunities , I'll try this stuff and see what happens.

Thanks !

[Motor City Hamilton]

Looks like I missed a few opportunities , I'll try this stuff and see what happens.

Thanks !

Had the same issue as you. Ordered new slider bolts/pins and new rubber slider boots. Make sure to run a drill through the hole for the rubber boot to get any rust or frag out of the hole. Fixed my issue.

[fishguyaz]

Bringing this back from the dead.

I did the full deal : new packed hubs , new rotors , new pads without hardware or springs ... Without the caliper on the wheel spins very free , With the caliper on there is significant drag ... I think , maybe it will free up after a few laps ... No ... So I rebuild the caliper ... Just as much drag as before.

What's next ?
- New calipers ??? Why ???
- New master cylinder ??? Why ???
- Anything I missed ?

I lube the crap out of the caliper pin( the one with the boot on it). syntheitic caliper grease from autozone.
i do this before every event as part of my prep.

edit: as already pointed out by mr dewhurst.

[Johnny D]

You could try the Rebuilt Race Calipers that Drago sells in the classified.
He only got pole in the National Runoffs, they couldn't be all that bad.
J~

[dmathias]

What is the reason for not using the springs?

[trey]

OK , I think I've tried all the caliper , lube , filing , drilling , hardware , springs , ect. ( BTW : I almost got tossed in SRF for this type stuff ) , and I'm still suffering from significant drag.

Could a weak master cylinder contribute to the piston not pulling back ?

[Keith Novak]

Trey, I've found some new pads fit very snug with brand new rotors. The pistons just push out far enough to install them. You didn't say whether or not when you back the pistons all the way out, prior to pressing the brake pedal do you still get the drag? If that's the case, last winter I took a couple sets of slightly used rotors to the machine shop and had them turned a little bit. Easier to install new pads and much less drag.

[Tom Hampton]

I went through this last spring, too. I found it was a combination of old calipers and an old master cylinder....AND....an unrealistic expectation after coming to a stop using the front brakes. An old MC can leak a small amount of fluid its piston, making for a soft/long pedal on application, and incomplete pull-back on release.

You don't say if the drag is the same on both sides...but, you do use "wheel" instead of "wheels". If its just the passenger side, it could be your proportioning valve. I've heard that it can develop a bit of a "check" valve trait as it gets old (limiting pull-back).

Also, there isn't much natural pull-back to begin with. Releasing the brake pedal releases the PRESSURE, but doesn't pull the caliper piston back much. The system relies on a small amount of knock back to separate the brake pads from the rotors. When you use the brakes to come to a stop, there is no knock back on that final application of pressure. So, perhaps everything is NORMAL. Knock back occurs from normal wheel movement due to road vibration and steering forces. To test, go out and drive around...maybe a parking lot? turn sharply back and forth, without using the brakes, to induce some knock back. Bring the car to a stop using engine braking, and e-brake only. Then jack the front end and check your wheel spin. I find that I can get ten revolutions of the wheel from a good spin using my foot on the drivers side, and 8 on the passenger.

NOTE: you can't use the ebrake and then check drag on the rear wheels...for the same reason. But the big deal in the rear is the adjuster, not lack of knock back.

When I first started troubleshooting this, I only got two revolutions on the passenger side. Between MC, caliper, and knockback I improved by 6 revolutions. I never did replace the prop valve because I was satisfied with the results above, and I remember it being really expensive even from MMS.

[Ron Alan]

One of the top guys at our regional last weekend had big time brake drag. Tried several things but no luck after 2 sessions. Changed out the MC as was suggested by a few and problem solved. They took apart his old MC and found a lot of gunk in and around key o-rings

[trey]

One of the top guys at our regional last weekend had big time brake drag. Tried several things but no luck after 2 sessions. Changed out the MC as was suggested by a few and problem solved. They took apart his old MC and found a lot of gunk in and around key o-rings

I'm thinking something like this is the issue ... I've tried new rotors & old rotors , new pads & old pads , hardware & no hardware , lots of syn lube & little syn lube , rebuilt the calipers , fluid change , ect.

Thanks