Brakes pull to the right a bit - Diesel Forum

**PeterL** · 11-19-2009, 02:52 PM

Well, this has got my mechanic stymied.

The truck pulls to the right when the brakes are applied. Not a huge amount, but enough that one cannot let go of the steering wheel. And, its not because of the crown in the road.. I've tested for that on flat surfaces.

My trusty mechanic found a right side caliper that was sticking and replaced that.

The other caliper is fine, the flex lines are good and the left slides are lubricated and working well.

Everything else seems to work well, but it still pulls to the right.

Any ideas what to look at before we start throwing parts at it?

Thanks

fordsforever73 · 11-19-2009, 03:06 PM

You did check for even tire pressure, right? You might want to check for any play in the tie-rods too.

**PeterL** · 11-19-2009, 03:24 PM

Thanks for your fast reply FF...

He says the front end - tie rods etc are fine. He also said that if there was low pressure in one tire, it would pull to the right all the time, not just during braking.

I will check the tire pressure myself later today.

Any other suggestions?

Thanks

FMTRVT · 11-19-2009, 03:58 PM

There is no way to "check" the hoses without xray or cutting them apart. But they are usually OK unless there had been repair work done lately or you have a lift.

It's not a matter of just checking the slide pins, but also if the pad ends are sticking in the brackets as well. Sticking in the brackets can be just as bad as the slide pin issue.

Anytime there is a pull it's also best to check both the front and rear brakes. A rear temp spread or issue and casue the same problem.

But you mentioned the the right front caliper was sticking. Depending on how it was sticking. Initially there is just a lot of hysteresis where the piston does not return, later it becomes and issue where the piston does not move.

But any situation where the pad does not retract from the rotor and allowing it to run hotter (semi-met materials are more effective hot so most often pull to the hot side) can casue the friction on the hot running side to carbonize more and therefore be more effective. The solution is to go out and do some of the "bedding in" stops that some friction material manufactures recommend. That is do about 5 stops from 50 to 5 miles an hour and cool for 1/2 mile between stops. You don't fully stop between each application. Let the brakes fully cool by driving for 5 miles then see what happens. Sometimes you have to repeat, but don't go too crazy as excessing repeat stops will heat the brakes enough to burn the caliper boots.

Now if there was new friction installed on the front then this would not apply.

In 30 years of testing friction material with full temperature instrumentation, we found that a test driver would start to observe a pull once there was a disparity of 100F from right to left side. And this was with new calipers for each 2 week test. Often just the pushing back a finicky caliper piston would do the trick if we didn't find a slide or pad hanging up. When we built a vehicle for a test we always checked the sliding force of the pads in the bracket and piston itself, and this could still occur. If the pad developed a heat conditioning due to waiting a day or two to get it on the lift, many time the flipping of the outer pads drivers side to passengers side would give enough of a friction or torque balance (high friction left outer, low friction left inner / high friction right inner, low friction right outer) that we could continue the test without further issues. In about 2,000 brake application all pads would be back to even friction.

But here my main concern would be to check the rears as they cause issues and when they go bad the wear out very quickly without the driver realizing it.

kenmullins · 11-26-2009, 12:34 PM

I had a very similar problem, but my E-350 Diesel pulled to the left when braking. We switched the tires on the right side to the left side and vise verse. The van still pulled left when braking. Next, based on a recommendation from FORD engineers we replaced all the brake lines -- same problem. Next we replaced all the calipers -- problem finally solved.

Hope this helps.
Ken

**PeterL** · 11-26-2009, 04:36 PM

Well, still having problems...

We replaced right caliper, slides working fine, pads, rotors are fine...

Rear brakes fine..

Any other ideas on this one?

Help!

66tiger · 11-26-2009, 05:23 PM

I don't know if this will help, but I had a 01 f250 that I had the brakes done on at a local brake shop, after brakes were done, truck would pull to the right slightly. Took it back to shop and they said it was an alignment problem, brakes checked out okay. Took it to an alignment shop, and they said everything was right on the money. Truck still pulled to the right. I took it back to the brake shop, & raised alittle stink. They pulled the tire again and looked at the right front caliper. Shop foreman noticed that the brake line was twisted from previous tech installing the caliper with the brake line twisted. That twist was enough to keep some pressure in the hose, causing caliper to stay slightly engaged. They took the caliper off, spun it around reinstalled it and that solved the problem.

davekusa · 11-26-2009, 07:00 PM

I worked at the ford dealer for many years and this was a big problem in the late 80's early 90's. Usually its a caliper, but not always. Could be alignment or even rear brakes.
Everything start with "Usually but not allways":

Try swapping tires side to side and drive it.

1. If the steering wheel pulls when you step on the brakes, its brakes
If it pulls without the steering wheel moving, its alignment, steering, susp.

2. If its brakes, try swapping front pads and front rotors side to side.
(Sometimes this actually fixes the concern). Check the groove that the pad sits in. Sometimes the pads get seized in there.

3. If it pulls the same way try front calipers, rotors and pads.

hope this helps

whitgallman · 11-27-2009, 10:28 AM

When I've had this happen it's been the rubber bushing between the radius arm and the radius arm bracket.

drl123 · 11-27-2009, 11:38 AM

Check the caliper slides. My 02 F250 was known for getting corrosion on the slides on the left side slides seizing the mechanism, resulting in the right side caliper doing all of the work. Changed the slides for new (available as kit at NAPA) and solved the problem.

Greg03PSD · 11-27-2009, 01:05 PM

Just a shot in the dark here, but have you tried bleeding the brakes (specifically the left front caliper)? Some air trapped in that caliper might prevent building pressure on the left side due to the air compressing. If the right caliper does not have air, it would build pressure immediately. The difference in pressures (higher on the right) could cause a pull to the right.

FMTRVT · 11-27-2009, 03:09 PM

Quote:

Originally Posted by Greg03PSD

Just a shot in the dark here, but have you tried bleeding the brakes (specifically the left front caliper)? Some air trapped in that caliper might prevent building pressure on the left side due to the air compressing. If the right caliper does not have air, it would build pressure immediately. The difference in pressures (higher on the right) could cause a pull to the right.

Common belief, but not exactly right. With air on one side of an axle's brakes it causes a slight delay in apply on the side with air, but the air will compress to the applied pressure and brake torque will even out. You typically feel a quick tug on the steering wheel towards the non-air side and then it goes away.

Air will require more fluid volume to that one side, but neither the pedal or master cylinder cares about that, they will just travel farther for more displacement. But if the applied pressure at the master is 500 psi, the air bubble then compresses to 500 psi, and the fluid downside develops 500 psi.