Twitchy steering with a big travel trailer (rear sway bar help?)

[txaggie]

Howdy all,

My 85 suburban has a 2” static drop (shackles rear, coils front). We replaced all steering and suspension components up front, new control arms, tie rod ends, borgeson quick ratio box, etc). We installed helper air bags for the rear when towing and it helped tremendously but when I tow my 33 foot trailer 8500-9000 lbs, my steering is twitchy as hell. Could this be due to the quick ratio box?
Would steering dampeners help? Also, no rear sway bar is present. Would a Hellwig bar help too?

 

[HotWheelsBurban]

Do you have a weight distributing hitch on the trailer with sway control? On a trailer that long I'd definitely recommend it if you don't have it. Rear sway bar on the Burb will help but squares didn't have them except for the duallies. My OBS Burb has a factory reset sway bar and it does help when driving and towing, but all I tow with it is an enclosed U Haul trailer (not near as big or heavy as what you have).
Also you want to look closely at how the movable stuff in the trailer is loaded. If there is too much weight bias past the axles it will be "tail heavy" and that will aggravate sway issues.
I've never driven anything with a quick ratio box, but I do know you need a steady hand when towing. How bad or rough are the roads where you're driving with the trailer? That can be a factor too.

 

[TotalyHucked]

^Agreed on the weight distribution hitch. Throw a picture up of your setup when loaded. Does the 'burb squat real bad?

 

[fast 99]

Tire brand, air pressure and incorrect load rating can contribute to unpleasant driving experience.

Assume alignment especially caster and toe is within spec. On 2wd toe changes with frame height change.

 

[Ricko1966]

If you don't have enough weight in the front of a trailer,it is very twitchy and can be very scary.

 

[txaggie]

Do you have a weight distributing hitch on the trailer with sway control? On a trailer that long I'd definitely recommend it if you don't have it. Rear sway bar on the Burb will help but squares didn't have them except for the duallies. My OBS Burb has a factory reset sway bar and it does help when driving and towing, but all I tow with it is an enclosed U Haul trailer (not near as big or heavy as what you have).
Also you want to look closely at how the movable stuff in the trailer is loaded. If there is too much weight bias past the axles it will be "tail heavy" and that will aggravate sway issues.
I've never driven anything with a quick ratio box, but I do know you need a steady hand when towing. How bad or rough are the roads where you're driving with the trailer? That can be a factor too.

thanks!

^Agreed on the weight distribution hitch. Throw a picture up of your setup when loaded. Does the 'burb squat real bad?

I have a weigh safe heavy duty distribution hitch that helps me dial in perfectly by weight. The squat is good with the rear air lift air bag system at 65 psi. I’m running some pirelli scorpions at 45 psi (Max 50).

 

[idahovette]

Could be tire squirm....Don't think those tires are stout enough for the load??

 

[DoubleDingo]

Howdy all,

My 85 suburban has a 2” static drop (shackles rear, coils front). We replaced all steering and suspension components up front, new control arms, tie rod ends, borgeson quick ratio box, etc). We installed helper air bags for the rear when towing and it helped tremendously but when I tow my 33 foot trailer 8500-9000 lbs, my steering is twitchy as hell. Could this be due to the quick ratio box?
Would steering dampeners help? Also, no rear sway bar is present. Would a Hellwig bar help too?

Ditch the passenger tires and get E rated tires that are meant to be used on 3/4 ton vehicles.

 

[DoubleDingo]

Could be tire squirm....Don't think those tires are stout enough for the load??

NOPE!

 

[txaggie]

I wonder what e rated tires are out there that are lower in profile?

 

[fast 99]

Those would be passenger or SUV tires. Will never work. No reputable tire shop would install P rated in the place of LT tires on a 3/4 ton vehicle, liability. Look at the load capacity on the sidewall.

 

[AuroraGirl]

I wonder what e rated tires are out there that are lower in profile?

Lower profile tires are easier to make E rated because the sidewalls are shorter , thats much less that needs stiffening. What size is the tire (the P-metric numbering (P225/65/16, for example)
Depending on how your trailer axles are setup and how you load it, those tires are either under-spec or severely dangerous in this situation

 

[TotalyHucked]

Agreed with the others, it's the tires. That's def not a heavy enough tire to be putting all that weight on

 

[AuroraGirl]

Also, get your caster angle measured or show us what your alignment (last one you had)
You have modified the height of your truck. Increasing caster , but it must be even side to side, will improve squirm and returnability , making it more confident handling


Also, having a power steering pump with the control valve sticking in the bore of the pump can cause you to have over pressure, over pressure will make the issue worse (wotn cause it, amplifies it)


I bring these things up because rear sway may be because your steering is darting around, causing your body and frame and axles and tires and thus trailer to swing around too. Its usually noticeable, but sloppiness from rag joints and worn boxes can hide these inputs and may be only noticeable with the trailer.

I think your tires are the first thing to address, and show us the trailer and explain how you load it will also be helpful. Using a hitch placing the trailer level with the truck with the new tires will be a good thing too
Edit: I see your title was asking about a sway bar, but your steering is the issue. So what I say applies, tires are still a big deal, because the tires you have will flex and influence the direction of the truck more than LT tires (Even a smaller load range than E but still LT will have less issues)

 

[AuroraGirl]

Howdy all,

My 85 suburban has a 2” static drop (shackles rear, coils front). We replaced all steering and suspension components up front, new control arms, tie rod ends, borgeson quick ratio box, etc). We installed helper air bags for the rear when towing and it helped tremendously but when I tow my 33 foot trailer 8500-9000 lbs, my steering is twitchy as hell. Could this be due to the quick ratio box?
Would steering dampeners help? Also, no rear sway bar is present. Would a Hellwig bar help too?

Id also like to see your steering geometry , and what box did you use? quick ratio (as in, less turns to full lock?) Will amplify the issue yes
not that you wouldnt have it with a stock box ratio, but it could be a factor. And what kind of shocks do you use?

If you want to keep your pirellis (look new) for ride comfort and use another set for trailing, you can save A LOT of money using 16s (perhaps the original wheels your truck had?) and purchasing tires for that size wheel. The original wheels or aftermarket 16s could even be made to look likeyour aftermarket wheels with your same factory hub caps

How heavy of springs are you rear springs? YOu have a light duty 3/4 ton is the reason I ask, if you didnt use new springs they may be slightly undersized for such a heavy (presumably) tongue weight