88' 350 brake problem

Reply Subscribe

Thread Tools

Search this Thread

Nov 7, 2011 | 03:07 PM

kwheatcroft

Thread Starter

Freshman User

Joined: Oct 2005

Posts: 44

Likes: 0

88' 350 brake problem

hi all, my 88 f350 w/460 is driving me nuts. It has pulled hard to the left for a long time. I changed calipers/pads, master cly, rubber brake lines. Took all metal lines apart and blew air through them to verify they aren't plugged--put back together, bled like crazy and still pulled left. I even verified the banjo bolt holes weren't plugged, and junction block is clear--still pulled to left!!

After approx 5k miles, my left inboard pad is down to the rivets and the right pads look new!
Is there a proportioning valve for left/right fluid transfer?

Also, sometimes the pedal goes away and feels like there's a slow leak, but it doesn't leak a bit, anywhere.... I can sit in the driveway and slowly push the pedal down--it keeps going... think its the booster?

I have heard about the RABS valve needing bleeding--is that the small valve on the frame, right under driver seat? Could that cause left/right pulling like that? I thought it is just for the rear brakes. I bleed till absolutely no air bubbles at all--clear fluid.

I am really frustrated at this point!

thanks guys,

Kevin

Nov 7, 2011 | 03:35 PM

Lazy K

Post Fiend

Joined: Jan 2005

Posts: 8,402

Likes: 10

Yes the RABS module is on the left frame rail where you describe. It is only connected to the rear brakes so has nothing to do with the front caliper dragging. However it may be the cause of the sinking pedal (the booster definately is not).
You seem to have covered just about everything as far as the caliper dragging is concerned. I take it that you looked at the hard line going to it to ensure that it is not kinked/flattened.
Only other thing I can think of is that the push rod from the booster to the master cylinder is too long. You could check that by backing off the two nuts that hold the master cyl to the booster so that the master cyl can come forward about 1/16 inch and take it for a drive. If that helps then you can pull the master cyl clear of the booster and adjust the push rod to make it a little shorter.

Nov 7, 2011 | 03:39 PM

jokerforever

Laughing Gas

Joined: Jun 2005

Posts: 820

Likes: 11

The RABS Module is a source of problems for a lot of us but it will only affect the rear brakes. This maybe a problem but this isn't your problem here.

Your right caliper is not working. You can tell because the pads aren't worn. Your left pads are doing all of your braking and that is causing the accelerated wear. Something isn't working on the right. You said that you changed a bunch of parts but was that on the left side or both sides. Did you change the caliper on the right side? If you did it could have been a bad part (it happens more than you think, especially with rebuilds). Make sure that you put your eyes on every inch of line. The line that goes over to the left side might have a kink in it. Keep at it. There are only so many parts in the system. Do a little detailed troubleshooting, look over everything and you should be able to find it.

Nov 7, 2011 | 05:35 PM

kwheatcroft

Thread Starter

Freshman User

Joined: Oct 2005

Posts: 44

Likes: 0

thanks guys. I will replace both calipers (again,) and see what happens. I spent a good deal of time checking the lines, but will do that again too.

Thanks for the pushrod advice--I would never have known to do that.

I now need to replace the left rotor. I looked on rockauto and noticed a few of the rotor descripitions recommend turning the rotors after they are mated to the hubs, what do you think about that? I never noticed a problem with vibration or pedal pulsing....

Any recommendations on brand of calipers/rotors to buy (or stay away from)???

thanks for the quick responses--I really appreciate it!

Kevin

Nov 7, 2011 | 06:42 PM

bashby

Post Fiend

Joined: Nov 2005

Posts: 7,437

Likes: 4

From: Charles Town, W bygod Va

I've never turned a rotor after mating to the hub... never had a problem.

Nov 8, 2011 | 09:08 AM

kwheatcroft

Thread Starter

Freshman User

Joined: Oct 2005

Posts: 44

Likes: 0

I haven't either, but I haven't done a rotor/hub job on this truck.

thanks man, have a good one,

Kevin

Nov 8, 2011 | 10:29 AM

andym

Post Fiend

Joined: Mar 2002

Posts: 19,402

Likes: 38

From: Bonita Springs FL

Is your truck 4x4?

First of all, never use riveted pads. Because you did now you have to replace a rotor that you wouldn't have had to if you used cemented pads.

I would have both rotors turned when you do the brakes. I don't think it's your problem, but having both turned will make the surfaces the same on both sides because if they aren't, that can cause a minor pull.

I have always had rotors turned after pressing the studs in to attach it to the hub. Every single time I've done this, it has warped the rotor.