Truck bucking when hitting the brakes?

It sure sounds like your gain is set to high! I also have a Chevy with the integrated brake control. My TT weighs in at 6200 lbs. I set my gain between 2.5 & 3.5, anything more and it bucks hard at slow speeds. I normally set my gain so it takes just a bit less brake peddle pressure when towing. I want to make sure that I am getting enough brake so that under hard braking the TT does not try to pass the truck and not so much as to feel it buck and lock up the wheels.

I also should add that this is a NEW TT so the brake pads are new, I am sure with time I will adjust the gain higher.

Do what feels right for you! It's your truck & TT, its a unique combination, no one knows how your set-up feels but you!!

Happy Camping!!!

freewayrandy wrote:

JBarca wrote:

freewayrandy wrote:
Integrated GM controller. Set at 6.5

I looked up your camper. Nice camper BTW.

https://www.granddesignrv.com/showroom/2019/toy-hauler/momentum/floorplans/328m

Where there toys in the camper when the bucking is occuring? Knowing if toys are in the back may not buck as bad on no toys and if so that will help to know on the cause. Was the TH fuel tank full or empty and where is it located in relation to the camper axles?

Do not know how loaded the camper is, it is a 12,400# dry weight camper and a 16,500# GVWR camper, if you have filled it that full, that is 1 ton truck need. Something less than full may fit in your 2500HD.

A trip to the truck scales my really help in this case. The bad bucking may be coming from the truck suspension being over it's ratings by too much.

I do not think gain on the brake controller is the issue. These new integrated controllers are generally super smooth.

Hope this helps

John

No toys this time. Fuel tank at the very back and almost empty.

Without the toys and fuel to counteract the heavy pin weight, you may be a lot higher in pin weight then expected. It is always an eye opener what "stuff" weighs.

Now that we know a little more about your situation, describe the bucking in the truck? Does this bad bucking start when you are going 50mph to 0 or 25 to zero? And is the bucking non stop until you stop once it starts?

Folks have been pointing to non functioning trailer brakes, to test if they are working, on a no traffic area go about 20 to 30mph and apply just the manual brake button to force the camper to try and stop the truck. (no truck brakes at this point) If there is no braking action at all, more gain can help some of that but if the brakes are greased up or way out of adjustment, gain is not going to really help that after it gets maxed out. With this test it may help separate the issue if it is with the camper or in truck suspension.

If there are no trailer brakes or very little, that problem has to be fixed regardless. With a heavy camper, the brakes may not lock up at 30 mph with full manual power but they should be putting one heck of a drag on and you feel it in the truck.

If you have good trailer brakes, then this can rule out some of the greased brake issue. And maybe some of the way out of adjustment issue. This leaves the truck suspension. A trip to the truck scale may help explain some of the bucking if you are way over the axle ratings.

Hope this helps. Let us know how you make out.

John

JBarca wrote:

freewayrandy wrote:
Integrated GM controller. Set at 6.5

I looked up your camper. Nice camper BTW.

https://www.granddesignrv.com/showroom/2019/toy-hauler/momentum/floorplans/328m

Where there toys in the camper when the bucking is occuring? Knowing if toys are in the back may not buck as bad on no toys and if so that will help to know on the cause. Was the TH fuel tank full or empty and where is it located in relation to the camper axles?

Do not know how loaded the camper is, it is a 12,400# dry weight camper and a 16,500# GVWR camper, if you have filled it that full, that is 1 ton truck need. Something less than full may fit in your 2500HD.

A trip to the truck scales my really help in this case. The bad bucking may be coming from the truck suspension being over it's ratings by too much.

I do not think gain on the brake controller is the issue. These new integrated controllers are generally super smooth.

Hope this helps

John

No toys this time. Fuel tank at the very back and almost empty.

Check your brake shoes adjustment as well as replace any pads that have grease on them. The activation gets non-linear when the magnet has to swing too far or the pads get greasy. Greasy drum brake pads grab and don't release evenly.

IMO the bucking is from the brake controller gain set too high. I experienced bad bucking after my rv school instructor set my gain at 7.5. I guess he was used to fivers with crappy brakes.

After my lesson I experienced a lot of chucking and bucking when I aggressively braked.


So I backed the gain down to 6.5 and the bucking and chucking went away.

No way is this too much trailer for my truck!

freewayrandy wrote:
Integrated GM controller. Set at 6.5

I looked up your camper. Nice camper BTW.

https://www.granddesignrv.com/showroom/2019/toy-hauler/momentum/floorplans/328m

Where there toys in the camper when the bucking is occuring? Knowing if toys are in the back may not buck as bad on no toys and if so that will help to know on the cause. Was the TH fuel tank full or empty and where is it located in relation to the camper axles?

Do not know how loaded the camper is, it is a 12,400# dry weight camper and a 16,500# GVWR camper, if you have filled it that full, that is 1 ton truck need. Something less than full may fit in your 2500HD.

A trip to the truck scales my really help in this case. The bad bucking may be coming from the truck suspension being over it's ratings by too much.

I do not think gain on the brake controller is the issue. These new integrated controllers are generally super smooth.

Hope this helps

John

After you've checked your adjustment, be sure to check trailer ground. If ground is bad, your system will try to ground through the ball, which can change (violently) when changing force from pull to push, bouncing, etc.

Had these kinds of problems back in the 70's with old horse trailers.

I assume the bucking is caused by the trailer.

Two things I can think of is first grease on the brake shoes or out of round brake drums.

Integrated GM controller. Set at 6.5

Low gain for low speeds, high gain on the highway.

What controller do you have?