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99 C2500 454 front end issue

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by EzraBrooks, Mar 16, 2013.

  1. EzraBrooks

    EzraBrooks New Member

    Hi,

    I'm troubleshooting an issue with my front end. It started recently while I was away and my fiance was driving it. She said she hit the curb once, but didn't think she hit it that hard.

    It pulls to the right. A little at first, then more and more as I drive. Eventually, it's quite difficult to keep straight.

    I had replaced the brake pads and shocks a little while ago, but didn't do the rotors or bearings. So, it seemed a good theory that there was a bad bearing.

    So I replaced both rotor/hub assemblies with all new bearings. Went well. Brakes feel nice.

    Didn't help the pulling.

    I'm looking for ideas on how to troubleshoot this and confirm a diagnosis before spending too much more money. It's an old truck that I would rather not take to a shop as they will tell me it needs new ball joints, bushings, and everything else they can hit me up for. The truck rode like a champ before I left town, so I just want to fix this problem and get back to driving it, not replace the whole front end because it's old.

    Any thoughts on where to start?
  2. RayVoy

    RayVoy Active Member 1000 Posts 100 Posts

    Perhaps it's the tire, maybe she hit hard enough to break a sidewall.
    Swap the fronts, see if it pulls to the left.
  3. geo1

    geo1 Member 100 Posts

    get a tape measure,check back and front measurements of front tires,2wd somewhere around 16th of an inch toe in,i think.should tell you if a tie rod end got tweeked
  4. EzraBrooks

    EzraBrooks New Member

    That's a great thought, as it is simple to test, and would be simple to repair. I will try that soon.

    Thanks for your time to reply.

    - - - Updated - - -

    Easy enough to check, thanks. I was just reading about alignment, so I even understood what toe in was. :)
    Would this kind of problem get worse after driving a while and then better after the car has 'rested'?
  5. EzraBrooks

    EzraBrooks New Member

    Well, it's not the tire. I swapped the two front tires and the problem is still on the right. And since it doesn't pull until it's been driven for a bit, 15-20 minutes, I don't think it's an alignment issue at this time.

    One theory I found searching around dealt with the brakes. Stuck caliper, for instance. A diagnostic method described to me has proven telling.

    After driving for 20 minutes, and the truck pulling hard to the right. I parked and walked around the truck feeling the brakes on all four wheels for heat differences. Left front rotor and both rear drums were warm, but easily touchable. But there was so much heat coming off the right front rotor, I didn't even touch it in fear of losing too much skin. Also, by the time I got to my destination, the truck was able to bring itself to a stop without my apply the brakes.

    So, I think it's safe to say I have a brake problem. Question is, how do I definitely diagnose the faulty component? I've spent a bunch of money on this problem already and would like to limit the further cost.

    I know enough about brakes to change rotors and pads, and I have a basic conceptual understanding of how the caliper works. But I've never bleed a brake line and don't have a lot of knowledge about the system upstream from the caliper. I know the bolts that hold the caliper onto the spindle float, and brake fluid pressure pushes the piston into the inside pad, pulling the caliper on the floating bolts and 'squeezing' the rotor. Normal back pressure of the rotor should push the piston back in when the fluid pressure is released, and the caliper should float back to center, relieving the friction of the pad on the rotor.

    I've checked, during the rotor replacement, that the bolts do slide. They don't slide really well, but they slide, as well as the left side anyway, which I think is key. So I think this is a piston retraction problem. Sound right so far?

    Here's where I'm stuck. How many places in the brake system could there be a problem that impedes the retraction of the piston after the vehicle/brakes are warmed up, but not when it's cold? Is the problem likely isolated to the caliper, or could it be in the brake line, or master cylinder, or some valve in between, or some other part somewhere?

    So I could use from further guidance from others. Thanks.

    - - - Updated - - -

    Continued research seems to be pointing me in two directions.

    A caliper that needs rebuilding (dirty piston piston/damaged seal perhaps).

    Bad brake hose to the caliper that is acting as a check valve when the brakes heat up and expand the fluid around the piston, forcing the piston forward.

    Looks like in either case, I'm going to have to learn how to bleed the lines. Looks like a bottle, a tube, some fluid, and an assistant is all I need for this part. Is that right?

    If I'm understanding things correctly, and since I have to pull the brake line off the caliper and bleed it in either case, I think if I pull the line off the caliper and then am able to push the caliper in and out, compressing the piston without too much trouble, then that would be definitive that it's the brake hose. Right? If I can't move the caliper with the brake hose disconnected, then I know the caliper is in need of servicing/replacement, but I might also have a bad brake hose. Does that make sense?

    If the caliper is bad, I'm thinking that since I've already replaced the rotors, wheel bearings, and pads, on both sides, that I might just splurge for new calipers and brake lines on both sides and call it done. Then, of course, my rear brakes will start acting up, you watch. :-/

    Thoughts?
  6. geo1

    geo1 Member 100 Posts

    you got it,have the new hose handy,but when you remove the caliper you will know whos at fault,might need a crow bar to get it off,keep posting,geo
  7. bazar01

    bazar01 Member 100 Posts

    Before you buy the calipers and hoses for the front brakes, why don't you remove the front brake pads and push the caliper pistons back as far back as possible with a C-clamp, reinstall the pads, pump the brake pedal until firm then test drive if it still getting stuck causing the vehicle to pull to the right?
  8. EzraBrooks

    EzraBrooks New Member

    Actually, I did that as part of replacing the rotor and wheel bearings. I will say that it was harder to push that piston in than the piston on the other side. But with the brake line connected, I don't think that tells me which is at fault, the caliper or the line. They're both really old though. So it might be worth just replacing them both. I hate the spend the money, but they are my brakes. Not an area to get skimpy in a behemoth like this.

    - - - Updated - - -

    Well, last night was fun. Replaced both calipers and both brake hoses. Went relatively well. I couldn't get the clips on the new brake hoses, where they join the steel lines, because they didn't fit the new brake hoses. But I think the brackets will hold for now. The new hoses came with a new 'bracket' which looks more like the greek letter omega, but they bent coming off before installation and are useless now.

    When I took the right front brake hose off, there was barely any fluid in it. Plenty came out of the caliper when I disconnected the hose, though, which I think confirms the theory of a faulty hose.

    I bled both sides, which went well, mostly, but the pedal is spongy. I think I let the reservoir on the master cylinder get too low, so I'm going to re-bleed all four wheels, in the proper order, and see where that gets me. I was too cold and tired to do it last night, so maybe tonight or tomorrow, if it's warm.

    I'm not taking it out of my driveway until the brakes feel more solid, so I don't know yet if I've solved the problem, but based on how the right caliper looked when I removed it, I think I got it.
  9. EzraBrooks

    EzraBrooks New Member

    I re-bled the front brakes this morning. Not even the tiniest of bubbles, so I don't think I let air into the system. I intended to bleed the back brakes as well, but how and the world am I suposed to get to that bleed screw? It's right behind the tall stack of leaf springs.

    Anyway, the brakes are still spongy, but work, so I'll be driving it today to see if I solved the original problem. Then I'll need to figure out how to make the brakes more crisp.

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