Hi,

2004 Dodge Ram 1500 4x4 SLT. 170,000 miles. Noticed a vibration four months ago. Back end bouncing while braking. Replaced brakes and a bad caliper. Also noticed rear shocks were bad (6 years old). Replaced all shocks (Monroe blacks). Started going through worn parts. Replaced all suspension bushings (except body isolators). New rear springs/shackles. New upper and lower ball joints. New Wheel hubs. New u-joints on drive shafts. New axles in rear and cv joints. Inspected both axle housings and replaced fluid/no shavings. Truck is tight. I have always had a shimmy since we started this project. It is a rebound vibration. It occurs consistantly but only when the truck is reacting to dips in the road - then it shimmys (feels loose). One year old tires were recently road force balanced. Based on when and how the vibration feels, I don't believe it is the tires, drive shaft, trans, xfer case, engine, rear gears... due to it not happening all the time but at all speeds, all rpms, in gear or nuetral (while going 40mph)... but rather when the truck is reacting to the road. I removed the front drive shaft and the vibration is still there. I was going to remove the rear and drive around in HI, but want to make sure I don't have a slip yoke in the rear of the xfr case that can come out and leak fluid (first question). I am leaning towards the bed of the truck above the frame. There is some rust at joints on the ribs of the bed floor from the underside... Any other thoughts are appreciated.

 

Warped rotors

 

Thanks. Rotors in the rear were replaced four months ago. Front rotors are a year old. No braking vibration is felt.

 

I would suspect a tire or bent rim. Tire maybe separated.

 

Thanks. We did the Hunter Road Force Balance last month and one tire showed a minor issue that was corrected by rotating the tire on the rim. I also rotated the tires front to back twice and don't feel any difference or shimmy in the steering wheel.

I am tempted to purchase new 17" dodge rims and tires on ebay for $1000. but given this test, I don't think that will solve my problem. But any future tire purchases will be on 17" rims with the best tires available.... The looks of the 20 are good, but not worth the other potential headaches...

Also, on a smooth road, I don't feel the issue... So thinking that if it were a wheel or tire, I should feel it consistently...


This is what the road force tested:


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Today, tires are much lower profile. The distance from the rim to the top of the tread is less and the sidewall is much stiffer. This means that minor problems can be amplified and transmitted into the car and you feel things a lot more than you used to.

But everybody says alright, we’ll balance the tires. That’s part of the equation but balancing isn’t always the answer. So you have to go a step further. What we have here is a Hunter Road Force balancer. This takes it to a new level.

This roller back here comes out against the tread of the spinning tire. It applies 1,200 pounds of pressure to simulate the weight of the vehicle on the tire as it rolls down the road. Now a computer in the machine, and sensors, sense variations in the tread. Stiffness, or the tire isn’t completely round, or anything that would prevent the tire from rolling smoothly when its weighted by the car.

Then it translates that into a road force reading. We have a warning that it is excessive. Next thing we do is take some measurements.

What we did is we took measurements of the rim. Of course the machine had already measured the tire. Now we can do what is called match mounting. We’re going to take the high spot of the tire and match it against the low spot of the wheel. It’s really more complicated than that, but to make it understandable… that’s what we’re doing. And it’s telling us here that we have 15 pounds of road force in the tire and if we swapped the tire around, moved it around on the rim, such as it’s showing us over here, that we can reduce this to 8 pounds total.

 

more info:

Thank you.

Fronts suspension has new cv joints, new stablizer bar bushings and end links, new upper control arm and ball joint, new lower control arm bushings and ball joint, new hubs, and new shocks. No noticable diving - everything seems new and tight.

Today I am going to reinstall the front drive shaft (since that is not the problem) and disconnect the rear shocks and see what I get. I also don't think it is the trans, xfr case, or rear shaft since i was able to do a water burn out and no vibration. I am convinced this has to do with the empty bed and the welds/oil canning of the bed, so removing the rear shocks should make it nice and bouncy and eliminate the harse rebounding I am experiencing. I am going to take a deeper look at the bed and see where it could be coming apart from the bed frame above the cushion isolators. My welder is on standby and I also have a rental car on standby. This sucker is making me physically sick after 60 minutes of driving...

Any other thoughts please keep them coming.

Thanks!