Tow Vibration after Bilstein 5100 Install-2017 Sierra All Terrain

4weight · July 1, 2019

All,

Have towed a 5x9 utility trailer with a Polaris Sportsman twice now since my Bilstein install. From 68-72 mph getting pretty big vibration, smooths some at 75 or above. Then comes and goes, kinda weird. First trip I thought it was the tire pressure on my trailer. Both were definitely under max pressure of 50 psi. Filled them last night and ran it today. Same vibration. Did not have this at all with stock Rancho shocks front and back. Same 2" level, fronts set at stock and the rear 5100's.

Alignment was done and it is perfect both with and without the trailer. My only thought is the extra height of the rear 5100's have changed the profile slightly and I am getting wind drafts that are causing the vibration. It's doable but pretty annoying to be honest. Non-towing the ride is sensational.

Please let me know your thoughts and thanks in advance.

4W

Racindave · July 1, 2019

Is it like a tire shake or a mechanical vibration?

garagerog · July 1, 2019

If you have room on your trailer to move the ATV forward some to add tongue weight to your hitch, that might be worth a try.

4weight · July 1, 2019

It feels like more of a drag or I hate to say it a trailer vibration. Certainly not mechanical but the truck is vibrating and get a bob in the steering wheel. If its a tire shake its from the trailer to the truck. I'm telling you without the trailer, the truck rides smooth as silk.

4weight · July 1, 2019

2 minutes ago, garagerog said:

If you have room on your trailer to move the ATV forward some to add tongue weight to your hitch, that might be worth a try.

Interesting Roger, I have the ATV riding more forward than usual, almost to the front of the trailer. Its a nice well built trailer with axle weight rated at 3500. Maybe there is too much tongue weight, maybe I need to back it up. Thoughts? I'm honestly a novice on this type of stuff.

Racindave · July 1, 2019

Do u have a pic of the hooked up loaded trailer? The weight needs to be over the axle(s).

BlancoSilverado · July 1, 2019

Did you just replace your trailer tires?

They might be out of balance, most shops do not balance trailer tires unless you ask, and still even then you have to watch.

Addition: Trailer tires should be set to max psi when cold.

Racindave · July 1, 2019

8 minutes ago, 4weight said:

It feels like more of a drag or I hate to say it a trailer vibration. Certainly not mechanical but the truck is vibrating and get a bob in the steering wheel. If its a tire shake its from the trailer to the truck. I'm telling you without the trailer, the truck rides smooth as silk.

Kind of weird... what you are describing does sound like a trailer tire going flat....

garagerog · July 1, 2019

6 minutes ago, 4weight said:

Interesting Roger, I have the ATV riding more forward than usual, almost to the front of the trailer. Its a nice well built trailer with axle weight rated at 3500. Maybe there is too much tongue weight, maybe I need to back it up. Thoughts? I'm honestly a novice on this type of stuff.

Could be the tongue weight is off, you could be right about having to much tongue weight, with the taller Bilsteins you probably wouldn't notice sag, with not enough tongue weight you would be getting sway. You could experiment with the ATV location on the trailer or better yet scale it and shoot for about 12-15% tongue weight of the loaded trailer weight.

swathdiver · July 2, 2019

Might be a busted belt on one of the trailer tires...

4weight · July 2, 2019

1 hour ago, Racindave said:

Kind of weird... what you are describing does sound like a trailer tire going flat....

Well both tires are at 50. Max psi. The first trip one was at 35 the other 20. Surprised it didn’t blow. Lucky I guess. Thought getting those square would make difference. None.