The owner manual says not to exceed 55 mph while dinghy towing or damage to the transfer case can happen. Does anyone know why? and what can be done to get around this?

 

NOTE: I didn't understand the term "dinghy towing" and none of this answer applies to towing the Blazer with all 4 wheels on the ground.

You read the manual?

If I had to guess, the weight of a trailer will make the "rolling radius" (distance from the center of the wheel to the road surface) of the rear tires smaller than the front tires. The extra weight "squishes" the back tires more. That causes the rear tire spins to just a little further (angle) than the fronts to cover the same distance, which makes the center differential gears spin constantly and puts a constant load and heat from friction into the center diff.

That's also why you should always run 4 identical tires on 4wd vehicles. Don't ever mix manufacturers or types of tires. And keep the tires rotated at the specified interval so they all wear evenly.
Don't tow a dinghy?

If you're towing a heavy load without an equalizing hitch (you're messing up already, but I'll go on), pumping the rear tires up close to the "maximum" pressure on the sidewall might help some. That way, the "squish" or flat spot at the bottom of the tire will be the same, front and rear, and the "rolling radius" will be the same and the tires will turn the exact same number of revolutions to cover a mile.

If you have an equalizing hitch, be sure to tighten the chains enough to level the tow vehicle. That distributes the weight more evenly.

 

Dinghy towing refers to towing a vehicle with all 4 of it's wheels on the ground, let's say behind a motorhome.

 

Can you remove the front driveshaft and reinstall it when you get there? Just a thought. Do you have a 4 button transfer case?

 

Allrighty then.

I learned something.

Of course, nothing in my first answer applies to that.

Do you put the transfer case into neutral for towing this way? That would seem to be required for towing with the wheels on the ground, to keep from spinning transmission internals from the wrong end, without the pump turning and providing fluid to the bearings.

 

Yes I have the 4 button transfer case. The owner manual says to put it in neutral but not to exceed 55 mph when towing. It doesn't say why it just says it will cause damage.

 

Yes I can put it into neutral, and that is what they say to do but not to exceed 55 mph.

 

The 4 button, (NV236) Auto transfer case has an oil pump and a clutch pack. When being dinghy towed, even with the case shifted to neutral, the driveshafts still turn the "internals" of the transfer case, but not the oil pump, leaving the clutch pack with insufficient lubrication. The work around is to dolly the fronts, and remove the rear driveshaft.

 

Or, even easier and better, a drive on trailer, all 4 wheels on the trailer.