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Front brake wheel wobble.

9K views 31 replies 18 participants last post by  moms98awd 
#1 ·
This has probably been discussed but a quick sift through and I couldn't find anything specific. I have always had this with my 1998 Astro AWD. Now has 180,000 KM. On the flat don't notice anything under braking, but coming down a hill and have to brake now and again to stop speeding up, and this is around 50 KPH, and I get what I call the death wobble. It seems to be only on hills round town. Perhaps when the rotors are not quite hot yet and heating up. Out on the highway on day trips down hills at higher speeds on highways doesn't seem to happen.
You probably know what I mean, during braking on hills the front wheels feel like they are wobbling and cause me to brake gentler than harder beacuse it will be worse. The steering wheel vibrates. Whole front end shudders. If brake gentle and not sudden hard applications, then I can keep it to a minimum effect.

I have had this van for about 8 years and its always been like that. I have even changed rotors pads and drums and tires and shocks over the years only to notice it still does it! Have had rotors turned for obvious warped rotors years ago, did not help the brake wobble thing. Have got fairly new Raybestos rotors, drums, pads and shoes. I replaced all 4 ball joints on the front (mostly due to split boots and dirty greasy water comes out when I did a grease job!) so did the ball joints as a matter of maintenance. I have then had it in recently for wheel alignment (its had one a few years back too), all tie rod and other joints are tight. I had recently put Moog idler arms too. This wobble still occures. With new tires, rebalanced, old tires too, still the same. Wheels rotated, still the same.

I learned to live with it as I was basically the only driver of this van. Until two months ago my son got his drivers license and said he thought he'd broken something when it did that for him. Stupidly I'd forgot to explain to him not to exceed speed limits on hills and then brake hard!

Is this common with these vans? Has anyone ever fixed theirs and found out what it was? Right now theres not much that can be done to it thats not been done already.

What I have always thought causing this is brake pad residue on the rotors, you know when they are hot when you park, or what ever causes that outline of the pad on the rotors, residue like staining that must wear off soon after driving and braking again will polish it off after awhile I suppose. So I assume round town, down hills, under load, cold brakes warming up, that when braking on this type of rotor/residue condition causes grabbing, and on each side at different intervals, causing more or less pressure on the rotor and the wobble is like a pulling as each side gets more or less braking for split second - Are you with me?

EDIT: I should also add that all these years I use a torque wrench on all the lug nuts so as not to cause warping rotors.

Thanks.

Nils
 
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#2 ·
Wow, sounds like you've hit all the trouble spots already! :confused: Any play in the wheel bearings or steering shaft?
Are the pads/rotors OEM or aftermarket? I've had aftermarket pads/rotors that performed poorly when hot.
 
#3 ·
You might want to look at the control arm bushings. they do wear out, and are not fun to change. Have you had it to an alignment specialist for discussion of the problem ?

Only other thing I might suggest is a steering damper. Not stock on any of these trucks, but it may just be what you need.

Bob
 
#4 ·
Started out when I got it had GMs drums and rotors, their part numbers molded in to the casts. When I put new rotors and drums on over time I used Raybestos, more meat. Same with Raybestos pads and shoes too. Theres no play in the steering, all checked out. I've had older vehicles worn out and never anything like this!

No I have not had it in to a specialst for discussion. I had the alignment done and never thought to ask at the time. I may go back...I just expect that when you tell them about it then they see $ signs! And I've never changed the control arm bushings.

I was more curious what causes this in the first place. I have had the front jacked up and checked for wear on everything several times, done those idler arms and ball joints, and everything else is solid. The alignment shop said everythings solid, so I wasn't concerned.

Bob, is there any images and/or part numbers for the steering damper?

Thanks.

Nils.
 
#5 ·
Hey Nils,

Like I said, these trucks never were fitted with a damper, so you would have to find an aftermarket unit that would work. What you describe, sounds to me, like when kingpins wore out on the

older cars and trucks. I don't know if they are still used, perhaps on F**d I-beam front ends, still. But, for the most part, Ball Joints stole the show in the front end arena. Cheaper and easier to service.

Best I can offer is to talk to an alignment tech that has a long grey beard. Ha.

Bob
 
#6 ·
BTDT. Replace your front brake rotors. Period. They're bad.

With an AWD clean the hubs, and all surfaces that the rotors set against.
Keep setting the torque on all the lug nuts as you have been doing.

The only other thing you can try is swapping the rotors from side to side, so that they turn in the opposite direction. That sometimes affects the shaking. Usually not much.
 
#7 ·
Thanks everyone.
Yeh, might just try new rotors again. Its been a while. On the flat under normal braking they seem fine. I might even do the idlers again, I know they are Moog, lifetime guarantee or what ever they said, but that doesn't mean they won't wear! They feel firm on the van when I grab hold of them. Not like the old OEM ones. That way if the wobble persistes then I have done as much as I can in defense!

Nils
 
#9 ·
'cudapaul said:
BTDT. Replace your front brake rotors. Period. They're bad.

With an AWD clean the hubs, and all surfaces that the rotors set against.
Keep setting the torque on all the lug nuts as you have been doing.

The only other thing you can try is swapping the rotors from side to side, so that they turn in the opposite direction. That sometimes affects the shaking. Usually not much.
don't swap the rotors, they are side specific, sounds like idler arm wear. any alignment shop should be able to give you a free diagnosis in minutes.
 
#11 ·
Is your van lifted in the rear at all? helper springs or air shocks? If so the caster / camber angle is going to be off from stock specs. I have heavy springs in the rear and will get the death rattle you speak of if I have alignment done at the shop. Last time I went and had an alignment done I said nothing about it, they did the job and checked all the parts, gave me a clean bill of health. I brought it back and the manager had me take the kid that did the job for a test drive, downhill braking over 45 mph in that thing scared him so bad he almost walked back. Since then I've found running a hair toe out solves the problem. It makes the steering more sensitive, a bump can turn you, and wears the opposite of the norm as toe in is standard which eliminates the "bump steer".
 
#14 ·
I didn't see that you replaced the calipers. I'm on my third set on our '94 with 193K. Got them maybe 4 years ago, but haven't driven more than 5K the last two years. Got them at Advanced auto for $15 each with lifetime guarantee. You only need to bleed the caliper, not the system. If you go that route, pay attention to the brake fluid. If it looks lousy, consider bleeding the entire system clean. I have not had issue with wheel cylinders, but at ten bucks each, they don't add much to a brake job.
 
#15 ·
I get nasty feedback through the brake pedal and steering wheel when i get on the brakes, so I assumed it would be the rotors (had this problem on a dodge). went out and bought Wagner lifetime rotors ($$$) and ceramic pads, pulled the wheels and the rotors look fairly new and pads about half shot. Figured replace them anyways ! soaked the mounting bolts down with PB Blaster, NO GO, heated the bolts up and the slide pins, still NO GO. not a whole lot of room in the wheel wells and dont want to burn my brake hoses, by the way my Safari is 03 awd and i put a 2" lift on it. I had the feedback before the lift. How in the h*ll do i brake the calapers loose so i can replace the rotors???? please help
 
#16 ·
Don't heat the bolt, this makes it tighter, heat the metal around it where it is threaded into. Look at the new one to get a better idea. When bolts are really stubborn I use a breaker bar or a wrench and tap with a hammer, Hold pressure with one hand and tap at the same time. Often several treatments of heat, PB blaster and tapping over a period of time will work the stubborn bolts loose.
Also be certain your turning in the proper direction, your looking at these bolts from the wrong side. I know it sounds stupid but to quote a friend of ours, "It took me many years to get this stupid!" :rockon:

lyle said:
I soaked the mounting bolts down with PB Blaster, NO GO, heated the bolts up and the slide pins, still NO GO. not a whole lot of room in the wheel wells and dont want to burn my brake hoses, How in the h*ll do i brake the calapers loose so i can replace the rotors???? please help
 
#17 ·
x2 on the break over bar , sometimes even an additional cheater leverage pipe on the handle of breaker , I have had to use a 12 in leverage cheater , and sometimes I have to use a 40 in steel pipe , the longer gets more leverage , a good soaking with PB Blaster , maybe soak overnight , be sure to use High temp lube on the pins / bushings when putting them back in , if the get hot they can seize and limit the travel of caliper on the pins , which can lead to rotors warping
 
#18 ·
thanks for the input, but i don't see how i would have enough room to even use a breaker bar. and trying to keep the #55 torx bit (for the sliders) in its position is dang near impossable, im afraid of stripping it and then really be screwed. the caliper bolts i think are 13mm head i dont want to cook the brake hoses and as of for those slider pins/bolts it was the housing i was heating up, not the bolts (my bad) Do you guy's think that this is what is causing my pulsating shimmy or am i wasting my time to replace the rotors and pads ?? what do the idler arms do? i see people say these go bad pretty much (may be different topic i dont know just asking) I cant find a manual that has any thing about the awd's, is their one?
 
#19 ·
I don't mean to use the breaker so much for the leverage as phantom suggests by using a pipe but because it is more solid than a ratchet it will transmit the vibes from tapping better, no extentions or swivels. This is the benefit of an impact wrench. The breaker I use most often in tight quarters is only 12" long w/ 3/8" drive.
 
#20 ·
The majority of the time pulsating brakes are due to warped rotors ,

When I use the breaker with cheater I turn the steering wheel so that the rotor is turned out so I can get a good angle on the bolt , like for the left side i turn the wheel so that the rotor is all the way left . that way I can see easily where the bolt is take right hand and hold the bit ,,,,or use a allen style L wrench with correct bit end(place bar over the L wrench) , and with left hand hold the leverage bar and lift up to loosen the bolt , that way I can keep it level and in place while loosening ,
sometimes getting the bolt out when that tight can mess up the bolt , so I just replace the bolt if that happens , if you get a good solid grip in the bolt it usually will break free albeit tough sometimes , you may try a good pipe wrench if you can get a big enough one in there
 
#21 ·
Mystrovan,...I have my 2000 awd in for the same problem. I am getting tires, idler arms full front & rear brake service (new rotors & pads..etc) I will post my results after fix. This is not the first time...I am the original owner. Usually rotors replaced seemed to do the trick. I think with all the weight up front on this van design it is hard on front brakes. Interested in reading your fix results.
 
#22 ·
mystrovan said:
Thanks everyone.
Yeh, might just try new rotors again. Its been a while. On the flat under normal braking they seem fine. I might even do the idlers again, I know they are Moog, lifetime guarantee or what ever they said, but that doesn't mean they won't wear! They feel firm on the van when I grab hold of them. Not like the old OEM ones. That way if the wobble persistes then I have done as much as I can in defense!

Nils
I went through this same thing until last year. New brake components did nothing to fix it over the years. Turned out to be the power steering pump which supplies the power boost for the brakes, it was pulsing in a way that made it feel like warped rotors and/or drums.
 
#23 ·
Continued from previous post. Picked up the Van...rides like new. Put on BFG TA's touring...was told Michelin MS-2s would take months. I had some serious interior noise which I thought was tires also....turns out it was wheel bearing. Alot of new parts now, .... eats my holiday money up,that is for sure.
 
#24 ·
Hey guy's just wanted to give a big thank you for all your input, its great knowing that there is people out there that are willing to help!! I got the callipers off and new lifetime rotors and ceramic pads on, but when i took the old ones off, the drivers side pads shown that the bottom piston was doing the work. so replaced that calliper and only shows very little signs of feed back, but i think its my fault couse i used the old calliper for a couple of day's till i put the new one on, probably wore the pad a little.So I finally got done with the van (at least for now).It looks awesome! :banana: put new shocks on and had to put air shocks on the back becouse when loaded my new BFG rugged terrain a/t's rubbed (235-70-16) at the front of the rear wheel openings. with the 2" lift it seemed as though my rear axle got moved front some ?? hope this is normal with the overland lift. Any way's thank you all. :ty: lyle
 
#25 ·
in the old days, the spring perch had a hole drilled in it and the locating pin in the spring cluster fit into it and positively located the rear end. the Safari van has a rubber cushion and there is a dimple in the spring perch so the nut on the spring cluster does not hit the perch. there is a lot of opportunity for the rear end to squirm around especially when you loosen off the ubolt and put a lift into it. when i put my lift in I drilled a piece of plate with a locating hole in it, clamped the spring cluster and flipped the bolt/pin so that the machined head (cylindrical) fit into the drilled plate. the drilled plate i welded at the ends to hold it onto the spring perch. this locates the springs exactly and does not allow the rearend to move around, additionally, you can center the rearend before you tack weld the locatiing plate. I also heated and knocked out the studs from the factory clamp and used bolts on the inner side of the setup, suppose i should take pictures. should you decide to replace the pin head bolt in the spring cluster any spring shop has them, i suppose GM parts counter would also. I don't see any difference since I tossed out the rubber cushions, doesn't squeak, no perceptible change in the ride. plus I centered my wheels in the rear end.
 
#26 ·
drmmhmd, that sounds like a good way of doing it,but I was lloking at the front spring mounts and it looks as though I could un bolt the springs and then unbolt the the mounts and turn them around andbolt every thing back up, it lookes as though this would move my rear back about 1/2- 3/4 inch and therefor stop the rubbing at the front of the wheel opening. what do you think? Also my front end shimmy seems as though it is getting worse when i apply the brakes, did i just waste a bunch of money? what the hang can it be causing this. new pads,new rotors, new left caliper, and still getting nasty feedback through the brake pedle and the steering wheel, heck the whole van shakes, but the wierd thing is there are times it stops beutifully with out any problems? why?
 
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