1996 GMC Suburban 2500 Violent Wheel Shake Please Help.

dhollock · January 29, 2012

Hi,

I have a 1996 GMC Suburban 2500 4wd with disc front brakes and drums on the back.

I have replaced the caliper, hoses, rotors, pads in the front. Replaced the shoes, drums, and cylinders in the back.

Balanced all tires and had a front end alignment.

I still have intermittent violent shaking. Smooth as glass sometimes and then it wants to shake your teeth out.

All parts taken off and rechecked. Rotors cut and drums turned just to be sure...

Pulled the abs fuse to see if that was the problem no difference.

I was wondering if the hydroboost could do this? A friend suggested bad control arm bushings or a steering position sensor?

Please any thoughts you have would be greatly appreciated.

markw8 · January 30, 2012

Does this only happen when you apply the brakes? If it happens on uneven surfaces without brake input, you have something worn in the front end. Also is it lifted or have oversized tires.

Mark

ChevyTech77 · January 30, 2012

What wheels and tires are currently installed on the vehicle?

Is there any brake drag on the brake system after the brake pedal is released?

Anything loose/worn in the front steering or suspension components?

Is there a steering stabilizer installed and if so, is it still good or worn out?

Airwolf2tv · June 25, 2014

Does anyone have any additional information or suggestions on this problem??

I have a 96 Yukon with 190K miles, which recently began doing the EXACT same thing. The front-LEFT brake heats up to the point that the truck shudders violently and almost uncontrolably....requiring 2nd and 1st gear downshifts to ensure any kind of certain stop. When it's cold, or when babying the stops, the brakes are practically perfect....maybe a slight lead to the left.

I had previously replaced all the brake lines with stainless lines from InlineTube.com, including all lines and components out to the calipers and cylinders. Other than InlineTube preformed line set, all other parts are genuine GM.

I replaced calipers with hard-to-find genuine OEM brand-new calipers....original factory calipers.

Multiple sets of rotors....both OEM and after-market slotted/drilled.

Multiple sets of pads....both OEM and after-market.

Replaced master cylinder with brand-new GM part.

Found I had radiator leak on left side....thought this was an ah-hah moment....coolant spraying over the left wheel well and caliper. Replaced radiator with brand new GM radiator. New pads. SAME behavior.

I have noticed that the upper control arm bushings on the left side are severly worn and/or missing. Is it actually possible this could cause such a problem?? I figured the slight lead-to-left might be caused by this.....but not violate erratic brake behavior.

This is so frustrating. This is a flawless truck...best GM truck I ever had....relagated to weekend runs to Home Depot and crap like that, and I feel like I'm taking my life in my hands!!

Thanks for any suggestions!!

00Silverado4x4 · June 25, 2014

I'd be looking at your front right caliper since your front left is apparently doing all the front end braking. You may have a caliper getting hung up or air in the line.

Airwolf2tv · June 25, 2014

Clarifications on my original post...so everyone has correct information:

1. The truck has factory alloy rims with 265/75/16 Michelins. Have always had these on there. In good condition.

2. This is a 100% stock truck. No modifications, lift, etc...

3. No drag on brakes. Calipers take-up fine.

4. I may have mis-stated the upper arm bushing situation. The bushings aren't "missing"!! I've just noticed that the rubber washers where the arm slips into the mounts are severely deteriorated.

Thanks again for anyone that can help with some ideas.

Nick

gmtech4 · June 25, 2014

Did ya get the steering looked at ?

Airwolf2tv · June 25, 2014

Mark:

Thanks, that's an excellent point. Behavior hasn't changed going from reman calipers to brand new calipers...maybe there's air in that cross-over brake line....like you said, causing there to always be more brake pressure on the left. That would explain the left lead.

The other thing I didn't mention is that a panic stop is really dangerous. The left caliper grabs nasty hard...makes the ABS go nuts trying to recover. Following your thought, it seems like most front brake pressure is going to the left.

I'll pursue some extensive bleeding of the right and see if that reveals anything.

Thanks

Nick

Airwolf2tv · June 26, 2014

Gov:

Any particular steering components?? I've never had any steering issues....it's pretty tight for nearly 200K...and there hasn't been any changes to steering behavior.

This whole deal really seems to be around that left caliper overheating.

I think my next step is gonna be to get the entire brake system professionally bled. I'm not sure if that means a vacuum bleed from up top or not?? Since the entire brake lines were replaced, maybe there's some air stuck in the system....even to the rear brakes, causing that front left to be out of balance. I'm not convinced that the traditional two-person pedal bleed is really effective beyond a simple caliper or cylinder change.

Thanks

Nick

MMC · June 27, 2014

Just a thought, check the u joints on the front axel.

gmtech4 · June 28, 2014

i road tested a 2013 with 15K Km on it and they complained about stabilitrac light comin on and a dragging like its in low gear ,,,,,i get in and drive away and all is good ,,,,,,until i hit the highway and pin it ,,at 80 km/hr it does the death wobble sumfin awful ,,,,,i turn around and baby it back ,and the stab light came on ,,,i pulled over on base and smelt brake pads ,,,went to each frt tire and right front was hot as a fire cracker lol,,,off to warranty lol for a rather sticky right front caliper ,,

i thought of this thread when it happened !!!! lol

lee123 · June 29, 2014

If you work on it ypurself, jack up frontend, put stands under it for safety, set park brake, start, put in 4X4 and hit brakes, see what i does. Irecommend not wasting moneyon parts. If u got new lines hopefuly u got new hoses. Air in lines, bad hoses, and bad bearings are what usualy cause this problem.

Airwolf2tv · June 30, 2014

Rob:

Great story!!...good luck with it. Smoking brakes definitely make things interesting!!

Lee - every line is brand new GM parts...other than the pre-formed stainless hard lines from InlineTube...which incidentally fit like a glove, if you need lines. I haven't ruled out bearings....can't say I've ever had one go bad, so I don't know what the behavior would be. The truck runs perfectly smooth and straight at 80MPH for long distances. It only seems to be hard braking that eventually brings on the left-front shudder. Granny drive it or leave out the cargo....and you would probably never know it had a problem....other than very slight brake lead to left.

Thanks for everyones input, really appreciate it. My next step is to have someone do a complete flush of brake fluid....just to know that it's done right with the right tools. Hopefully that solves the problem!!

daxr · July 1, 2014

If you work on it ypurself, jack up frontend, put stands under it for safety, set park brake, start, put in 4X4 and hit brakes, see what i does. Irecommend not wasting moneyon parts. If u got new lines hopefuly u got new hoses. Air in lines, bad hoses, and bad bearings are what usualy cause this problem.

If you have four jackstands, put the rear up too and run it in 4wd. If you get a vibration in the wheels then, you know its a rotating part out of round or out of balance (most likely). Having a good lift, that's the first thing I do checking a vibration problem. If a tire is out of round you can usually see it pretty easily. With it in the air you can also apply the brakes, let them off, and hand-spin the wheels to make sure the brakes are releasing, and releasing evenly.

If its brakes causing the wobble you can look at the rotors - the color should be a uniform dull grey (if using ceramic pads) or a uniform silver (if using semi-mets). If a rotors is silver on one surface and black on another its usually easy to see, then a resurface on a lathe should take care of if. New rotor doesn't mean its runs true - problems do happen. If you have a rotor problem make sure the caliper pistons and slides aren't bound up, as that can cause rotor overheating and run-out problems.

Bearing and bushing problems don't generally cause vibrations, but they can let them propagate more freely.

Airwolf2tv · July 21, 2014

Ok, so I have a brief update after typical delays getting back on this and getting it to the shop.

I have a great STS shop near my house, so I decided to have them take a look. One of the managers/mechanics also has a 98 yukon/tahoe, so he's very familiar with the beast.

Their discovery is that the left rear shoes are completely shot, while the right rear has full shoes. So after taking a fresh look, doing a skilled ABS bleed, and road testing....they are preliminarily determining that the left rear is actually the root cause of the problem. No left rear braking....causing left front to overheat. Not much unlike the previous hunch above that maybe the right front was weak. Either way, it makes sense that lacking right front or left rear is likely to cause excessive braking up at the left front. I had to take it back for the weekend, but returning it this week so they can finish up.

I need to dig out paperwork, but I recall the GM dealer saying they grinded out the grooves in the rear backing plates because it was causing the shoes to stick. So I think it's safe to assume that isn't the current problem. I'm think maybe time for all new hardware in the rear...??? I believe it's all original. Maybe the shoes aren't taking up properly??

Anybody have any ideas on this new development?? Good idea to put all new hardware in the drums??

Thanks again!!

Nick