suburban - shaking while towing...

[cfanto]

Hello,

I'm trying to isolate an issue I experienced this morning while towing my SeaRay 210 Sundeck to get it winterized. At approximately 30mph, the vehicle begins to shake pretty bad. It stops shaking when I drop her below 30mph. At first, I thought it may have been the road, but it's doing it on streets that I've driven on before. Thankfully, it was a short trip to the shop.

My 2003 Suburban never does this shaking when I'm not towing the boat... could it be the trailer? I was thinking that if it was my tranny, that it would be doing it all the time... regardless if I'm towing or not (right?). She was driving nice and smooth on the way home after having dropped the boat off at the shop.

I recently had the 30k mi. service performed on the Suburban & the shop didn't bring up any issues to my attention. The trailer was also recently serviced. Having had the trailer bearings repacked & its brakes serviced. The only thing yet to be done is the trailer tires... the treads look like they're good, but they're "spider-cracking" on the sidewalls... could it be the trailer tires?

The boat's dry weight is 3550lbs, add an extra 300lbs for gas., and then probably 1000-2000lbs for the tandem axle trailer (I'm guessing???). I don't believe I'm over-taxing my suburban (4x4) tow capacity.

Any insight would be appreciated...

thanks!

[EagleTalons]

Have your Burban tires been aligned lately?

[dwill3015]

Try towing something else to see if it reacts the same way.

[tbplus10]

It's the boats way of saying it isnt ready to be put away for winter, it still wants to run some.

I'd look at the trailor tires balance and pressure.
I would seriously doubt your overtaxing the truck. The loaded weight for that combo is around 5100lbs, (owned the same boat a few years ago) and shouldnt pose a problem for towing.

[tlperry68]

I would tend to think this has something to do with rotation. Let it be tires or trailer axles at 30 MPH there is enough mechanical vibration / harmonics to bring on the shaking. Can you tell if the trailer tounge is making a lot of noise like the trailer is tugging on the hitch ball?

[cfanto]

This is an old thread, but realized I never updated it with a solution...

Well, I'm just thankful that the issue was indeed with the trailer itself & not with the 'burban's drivetrain. After replacing all 4 tires on the trailer, the violent shaking went away.

[k.daddy1]

Have you had the U-joints in the drive shaft checked? They may not loose, but maybe dry. With no grease in the cup bearings the u-joints maybe binding under load.