Chevy & GMC Vans

Since lifting the front i now have a rumble/vibration at idle and low speed, turning around etc. only while in gear ? Once i get moving faster its not as noticable.
Any ideas ?
It was not there before the lift.

what kind of lift?
body blocks?

Yes 2" body pucks and overland bumper brackets

That could be two things. Make sure the tailpipe isn't touching the springs. If not, it's probably your pinion angle, and the fix is to shim it, or adjust rear spring height.

viewtopic.php?f=5&t=6498&p=65720

I was under the impression that a body lift shouldn't affect pinion angle as the subframe that hold the motor and trans is effectively in the same spot it was prior to moving the body up 2".

swapping springs, or lift blocks in the rear will affect pinion angle as your moving the axel down, thus changing the driveshaft angle.

I believe that is the difference between a suspension lift, and body lift I believe. Our vans are a half and half. body lift via pucks up front, suspension lift via springs or blocks in the rear

could be wrong though.
shane

The pucks move the body away from the subframe. The rear axle is connected to the body and the driveshaft is connected to the subframe, so the angle must change. Only an angle finder will tell you for sure. Some higher springs might have been a better investment.

While dropping the front lessened the angle of the driveshaft, you also shortened the needed length of the shaft. Worst case is your driveshaft could now be too long and is causing problems at the transmission end where it slips in. Probably not, but something to consider.

I think I might just play with some axle shims and see what that does for you. While things are supposed to work a certain way on paper, they don't always seem to cooperate in the real world. You may find a slight tweak of the pinion angle fixes this.

timelessbeing wrote:The pucks move the body away from the subframe. The rear axle is connected to the body and the driveshaft is connected to the subframe, so the angle must change. Only an angle finder will tell you for sure. Some higher springs might have been a better investment.

based on my knowledge of trigonometry, and angles, (I'm a carpenter, angles are kind of my thing) I cant see a 2 inch rise of the front of the van changing an angle at the tires by very much, as the changes decreases closer to the pivot point, i.e. the axel, maybe a millimeter, in which case I wouldn't call that a big change, like .025 of a degree, but when you lift anything you are messing with a a bunch of angles, not meant to be changed, body lifts are the only way keep stock suspension specs, while gaining room for bigger tyres.

its like saying its only like 1/8 of an inch out of level.
An 1/8 out of level over 4 feet translates to 5/8's over 20 feet

maybe get some 1 deg shims throw them in and see if it changes, if it gets better, leave it, If it gets worse, take them out.

check your u joints, pinion nut, and diff fluid. too if no one else has mentioned that.......

2" over 4' is a difference of 2.4 degrees.

I would definitely check pinion angle in relation to the transmission output. They need to be within 0.5 degree of each other or you will get vibrations.

I just purchase an 04 awd cargo van. It's in great shape, only 45,000 miles on it. It was previously owned by the water utility company, I don't know if that's a good thing or a bad thing. I am planning on doing a little work on it to make it it into a camper. Thinking about installing a 2" lift also. My question is regarding the stock existing suspension on my van. The back looks like it is already at least a couple inches higher than the front. Is that how the stock suspension is set up or did someone modify it, perhaps to accommodate heavy cargo?

It may have heavy duty leaf springs (how many leafs in each?) and/or sagging torsion bars which can be adjusted to even out ride height.

claudconger wrote:I just purchase an 04 awd cargo van. It's in great shape, only 45,000 miles on it. It was previously owned by the water utility company, I don't know if that's a good thing or a bad thing. I am planning on doing a little work on it to make it it into a camper. Thinking about installing a 2" lift also. My question is regarding the stock existing suspension on my van. The back looks like it is already at least a couple inches higher than the front. Is that how the stock suspension is set up or did someone modify it, perhaps to accommodate heavy cargo?

My guess is it is factory stock. The last new vans I saw sold out of the local Chevy dealer all had the butts sitting unusually high (when compared to my stock '96).