This started a few months back, going down the hill the front end shakes like crazy in 2 certain spots. Next day turned the rotors and put the pads back on and everything seemed fine. Following week same 2 spots did the exact same thing, but when I tried to slow down it seemed like the shaking got worse. Had the Idler and Pitman replaced few days later. Following week no shaking, thought I had it fixed. Week after that, came back again....Dealership said everything looked ok. Didnt know what else it could have been so I decided to do my route backwards....Never had the issue going down on the new side. So today I had to do the route the orig way and it happened again...I prepared myself and slowed down to about 40. I literally had to stop in the lane to get the shaking to stop.

Ive noticed it is worse when I have it stacked from the front of the fender-well to the back door. It also slightly happens when I hit a fairly large bump in the road.....

Rotors are good....
New Idler/Pitman Arm...
Tires are good..........


Any ideas on what can be causing this?
Thanks
Brian

did you check out the calipers?

It's the rotors. It does not take much warpage to cause this shake when they "rotors" get hot. I have put up with this for over 350k have had new rotors,pads 4 times and have done both calipers twice. It only takes one good long hard stop to do it. The first time it happened to me I was in PA going down a mountain at 60mph and had to slow down quickly because some one pulled of the shoulder in front of me.:eek:. I thought the wheels were coming off, the steering wheel jerked out of my hand and it scared the crap out of me.

GM uses the same brake set up for the diesel and gas vans and I believe the extra weight from the diesel (about 700 pounds) is over taxing the system when you get near the front axle capacity, which is only 4300lbs. My front axle with me and a full tank of fuel and all my stuff in the van comes in @ 4200lbs. So the second I load something forward the rear axle I am pushing over the axle capacity.

The only solution I have found is to not use the brakes over 40 mph. I use the trans to slow me down (when loaded) and I start slowing down way early. I am looking at getting EFI live so I can have a tune with a turbine brake which will also keep me from using my service brakes. I have 420k on this van and have put up with it since about 70K. Coincidently @ 65k I added a rooftop A/C unit and a sleeper just behind my front seats (about 450 pounds) and the next thing you know I had the problem. So I think we are over taxing the front braking system on these trucks.

p.s. I know alot of people who have the 6.0 version of these vans and none of them have this problem as bad as I do. I usually ask what there front axle weight is when they are not load and it is only around 3000-3400 pounds. So they are not over taxing the front brakes.

just my .02

Have you had the truck aligned? Post the alignment numbers if you have them. How is the tire wear? I doubt it's the rotors. When I did my brakes the front rotors were bad and the rear had a slight vib to them and outside of your pedal pulsating from the warped rotors it never caused any shaking like your talking about.
The brake's on the 03 and up vans are very good but have the same issue's the trucks do with corrosion and sticking pads. Search in the drivetrain section and you will see a sticky on the trucks brakes and how to maintain them.

My 2000 would do it and it was not the rotors. I never did figure out what caused it. But it sure gets your attention.

I have the van aligned every 60k. I don't have the numbers but I will not let it leave unless it is under +/- 1.5 on caster/camber/toe and thrust. I have the same shop/tech/rack do it and they do it with me in it behind the wheel.

No unusual tire wear, I get about 120-150k out of a set of Firestone Transforce HT tires. Rotate every 30k front to back only, no crossing. The rear rotors and pads are org. The rear calipers are not seized or corroded or leaking for that fact. 30k ago I had the rear system checked out and had the rotors checked for run out and there was less than .002" and the pads are at about 60%.

The brake bias is off on this van and always has been, ever since new. I even went as far as checking the rims for damage and there was none and the tires always balance out with less than 2 ounces of weight per tire. Everytime I go in for a brake job (because of the shaking) I have the runout checked on the old and new rotors. These rotors will give you a severe front end shake at just +/-.004 or worse runout.

Every time I use to put new rotors/pads on I get about 20-25k out of them before the run out is at +/- .004 or better. Then I went to babying the truck when braking, i.e. no brakes above 40 mph and very light pedal under 40 mph. and the rotors will last me about 70-75k. I have 70k on them know and I am having them replaced tomorrow. Because I did 1 panic stop on the interstate from 60mph to 20mph (truck rolled over right in front of me) and that was all it took to warp'em.

I have the van aligned every 60k. I don't have the numbers but I will not let it leave unless it is under +/- 1.5 on caster/camber/toe and thrust. I have the same shop/tech/rack do it and they do it with me in it behind the wheel.

No unusual tire wear, I get about 120-150k out of a set of Firestone Transforce HT tires. Rotate every 30k front to back only, no crossing. The rear rotors and pads are org. The rear calipers are not seized or corroded or leaking for that fact. 30k ago I had the rear system checked out and had the rotors checked for run out and there was less than .002" and the pads are at about 60%.

The brake bias is off on this van and always has been, ever since new. I even went as far as checking the rims for damage and there was none and the tires always balance out with less than 2 ounces of weight per tire. Everytime I go in for a brake job (because of the shaking) I have the runout checked on the old and new rotors. These rotors will give you a severe front end shake at just +/-.004 or worse runout.

Every time I use to put new rotors/pads on I get about 20-25k out of them before the run out is at +/- .004 or better. Then I went to babying the truck when braking, i.e. no brakes above 40 mph and very light pedal under 40 mph. and the rotors will last me about 70-75k. I have 70k on them know and I am having them replaced tomorrow. Because I did 1 panic stop on the interstate from 60mph to 20mph (truck rolled over right in front of me) and that was all it took to warp'em.

If your rear brakes are factory with that many front brake jobs then they are not working right. I know the abs module controlls the brake bias front and rear but you must have an issue.
I have done plenty of panic stops with no issue in this thing.

If your rear brakes are factory with that many front brake jobs then they are not working right. I know the abs module controlls the brake bias front and rear but you must have an issue.
I have done plenty of panic stops with no issue in this thing.

Well took it to a stealer today here in NM. and they told me nothing was wrong. I then took the tech on a test drive and within 2 miles the steering wheel was going crazy and the pedal was pulsating. I looked at the tech and said NOTHING F-IN WRONG, RIGHT!!!. He said the run-out was okay and that the calipers were free and sliding correctly, and everything looked good. He asked if I had any codes I told him no. He said there is nothing he can do then. Got a hold of the service manager and let him know how displeased I was that his trained tech said he can't do nothing about it. Service Manager told me to bring it back on Wednesday when there best tech is there. NOT GOING TO BE HERE AFTER MONDAY!! So another $75.00 & 3 hours wasted. If anyone wants to dive into this problem please let me know. I am willing to drive almost anywhere to get this resolved!!

Typical dealer crap. There is usually a shop someone can recommend depending on your location, post up where you live.

Typical dealer crap. There is usually a shop someone can recommend depending on your location, post up where you live.

Easy!! I live in the van. I run the lower 48 and most providences in Canada:D

Different place every day or 2!!

No unusual tire wear, I get about 120-150k out of a set of Firestone Transforce HT tires. Rotate every 30k front to back only, no crossing.

Wow. How do the tires ride? Quiet? Good in snow?

How many miles does your van have?

Tires are a highway tread and are very quiet and smooth. On the snow not so good. I carry a set of chains with me and I have to use them every time the chain law is in effect. I have also had to use them in parking lots and unplowed roads, even if the state does not have a chain law.

As of today 3-7-11 I have 420,916 on the clock:D

My Van just did the same thing the past 2 days. It was in the same place on a bumpey road. I popped my head out the 2nd time as I was slowing down to see the front wheel violently wobbeling back and fourth. First time it happen thought I was going to crash and burn.
Its gotta be a combination of crap tires rotars and idler arm pitmen arm.
I think its mostley the way the van is loaded along with tires. I usually put my stuff at side door. Today I put it all at the back and it did not happen.
I took my good tires off that I use for winter and put my crappy tires on hoping to get some better mpg with the highway tread. A bit worn and chopped.

Could the vibration be the center steering link wobbling back and forth? I read on this forum somewhere that there is a company that makes replacement pitman and idler arms for the trucks that eliminate this wobble.

What company would that be? MOOG?

What company would that be? MOOG?

ok, did some searching. the company is Cognito. there is also another version made by Exaxt. if you search those names on here, you'll find a lot of info.

i wonder if the gm vans share the same steering components with the trucks. i would imagine so.

OK got about 90% of the problem solved. Van needed idler and pitman arms. Tech said I should look in to getting a after market steering damper. He said it will be a challenge to get one mounted on the van, but it could be done. I just had all 4 rotors turned (on vehicle) all caliper pins re-lubed and replaced the idler and pitman arms and the shimmy is all about gone. First thing we did was replace the idler and pitman arms then test drove it, There was a huge difference (for the better) then went on to turning the rotors and cleaning and re-lubing the caliper pins.


Hopefully I can find a steering damper to mount on the center-link, anyone have any ideas on this??

I think an idler arm and pitmen arm support would help as well.

So the problem has been solved....It was the front right tire and slightly warped front rotors.
The belts inside the tire were starting to separate.That mixed with the warped rotors would cause the problem. Slapped 4 new tires on and had the rotors turned and it has completely gone away......:D

Thanks for the update . Glad all is well . I need to buy a couple of tires myself ,no shaking,just plain wore out .Turns on wet pavement are starting to bring yee old tail end around .

This started a few months back, going down the hill the front end shakes like crazy in 2 certain spots. Next day turned the rotors and put the pads back on and everything seemed fine. Following week same 2 spots did the exact same thing, but when I tried to slow down it seemed like the shaking got worse. Had the Idler and Pitman replaced few days later. Following week no shaking, thought I had it fixed. Week after that, came back again....Dealership said everything looked ok. Didnt know what else it could have been so I decided to do my route backwards....Never had the issue going down on the new side. So today I had to do the route the orig way and it happened again...I prepared myself and slowed down to about 40. I literally had to stop in the lane to get the shaking to stop.

Ive noticed it is worse when I have it stacked from the front of the fender-well to the back door. It also slightly happens when I hit a fairly large bump in the road.....

Rotors are good....
New Idler/Pitman Arm...
Tires are good..........


Any ideas on what can be causing this?
Thanks
Brian

Both my vans have the same problem from a month or so of new.
Empty or full they shake, braking down the large hills going to limerock park racetrack.
they dont shake the other direction.
The dealer has replaced almost everything they can think of.
Im almost thinking its the road, but my trucks dont have the problem.