Towing a trailer

[Bigburb3500]

I towed a 7000-lb trailer with a half-ton Suburban. I broke stuff. The rear axle. Several times. While on vacation.

The weak link in these half-tons is the rear axle. It's, frankly, just weak. It doesn't like to be at max load, and it gets hot if you're on a long trip.

Are you going to be towing 60 miles up to the lake? Go for it. Or are you talking about cross-country road trips? That would be a big "no."

Unlike a pickup, the SUVs have a lot more weight on the rear axle - lots more body and glass. This in turn ends up overloading the rear axle before you get anywhere near the vehicle's "tow rating." Don't forget, people, pets and gear also add to the rear axle weight.

Look for "half-ton towable" trailers. They'll be light enough that you'll be less likely to overload that rear axle. Personally, I'm less concerned about the length, because there are hitch setups like the Hensley Arrow that eliminate sway, as opposed to a simple friction sway brake.

Last thing - more tongue weight means more stability and less sway. Of course, that runs completely afoul of trying to keep from overloading that rear axle. So it's a bit of a tightrope walk. The main reason I upgraded to my 2500 is because the rear axle can carry DOUBLE the weight of the half-ton trucks. As opposed to being the WEAKEST link on the half-tons, the rear axle is the STRONGEST part of the 2500 powertrain.

Thank you for commenting, I couldn’t remember your handle as I knew you would have great insight!

 

[j91z28d1]

curious what broke in the rear end?

 

[intheburbs]

curious what broke in the rear end?

First time it threw the pinion bearing. Partially my fault. The trailer brakes were not operating at 100% and I was downshifting whenever I needed to slow down. Came up to the Ohio Turnpike toll booth near Youngstown and just as I was downshifting to first we hear a loud bang and then what sounds like bolts in a blender. Got to spend 3 days in Youngstown instead of Washington DC.

Second time was a catastrophic failure from overheating. I don't know if the axle oil cooked off or sprung a leak, but the rear end went into nuclear meltdown and seized just outside Mitchell, SD. Again, got to spend 4 days there instead of Yellowstone and Rushmore. Had to truck in a new axle from Minneapolis. Ended up traveling the rest of that trip at night to keep axle temps down.

Fortunately, we have AAA+rv, so the costs of towing (flatbed for Suburban, pickup for trailer, up to 200 miles) were zero.

That was the gift that kept on giving. I didn't want to waste another day breaking in the new rear for 500 miles before towing. We hitched up and drove away. A year later the axle started chattering and grinding. We replaced the axle under warranty, but labor was not covered.

So that truck just rolled 300k miles earlier this year, has the original engine and transmission, but is wearing rear axle number 4.

 

[j91z28d1]

wow that's pretty amazing. sounds like a miserable time for it to happen too.

I'm not up on the different rear ends, just that there's a small and a bigger 14bolt I think it is? does the 3500 have a even bigger rear end?

 

[Foggy]

Until this thread, I didn't even know that a late model suburban was even
made in a 2500/ 3500 platform.. That would have been my first choice
5+ years ago... Maybe they were just out of my price range so i never even looked

 

[Bigburb3500]

wow that's pretty amazing. sounds like a miserable time for it to happen too.

I'm not up on the different rear ends, just that there's a small and a bigger 14bolt I think it is? does the 3500 have a even bigger rear end?

The 3500 have the 14bolt rear end off a 3500 Silverado. It’s not apples to apples but it’s beefy. If I’m not mistaken I think the rear ends in 2500/3500 Silverados are identical as well, biggest difference is suspension which allows for the higher capacity rating.

**over simplification

The biggest difference with a 3500 is the engine is old school - 6.0 Vortec and the trans is the HD 6L90. Lots of cooling too. They are hard to find but out there if you are patient.

 

[Bigburb3500]

Until this thread, I didn't even know that a late model suburban was even
made in a 2500/ 3500 platform.. That would have been my first choice
5+ years ago... Maybe they were just out of my price range so i never even looked

2500 Suburban production ended in 2014 and 3500 ran 2015-2019.
2500 you could buy at a dealership but not many stocked them. They were substantially more than a normal Suburban (also could get a GMC Yukon version too).
3500 were for fleet buyers only. You could not roll up and order one as a normal buyer. Most applications were for aftermarket upfitting with bullet proofing or for the railroad to add the attachments to drive on the tracks.

 

[strutaeng]

Yeah, the 10 bolts have always been a weak link in the GM trucks until recently. They'll survive an overload over the weekend hauling or loading, but push them ******* on a daily basis and they'll let you know when they break.

Once upon a time I had found strength numbers for the 10 bolt, the 14 bolt 9.5" and the 14 bolt 10.5" axles and the numbers told the story. I'll see if I can find that source. These were the older GM axles. I can only assume the newer HD axles are even stronger.

Edit: WTF?! h-a-r-d got edited out! LoL

 

[strutaeng]

Ok, here are the numbers I had found:

10 bolt:
8.5" ring gear 3,800 lb ft

14 bolt:
9.5" ring gear 5,000 lb ft
10.5" ring gear 6,242 lb ft
11.5" ring gear 8,321 lb ft

@Bigburb3500 Isn't your rear axle some monster like 12" ring gear axle? I know the newer axles are even bigger than these I posted.

Also, this says 8.5" for the 10 bolt. Essentially, a 8.5" and 8.6" are the same. The ring gears/pinions are even interchangeable. They are commonly listed as 8.5/8.6.

You can even do some basic multiplication of your engine torque times transmission gearing and axle gearing to see what your theoretical torque is at your wheels (assuming no frictional losses).

 

[Bigburb3500]

Ok, here are the numbers I had found:

10 bolt:
8.5" ring gear 3,800 lb ft

14 bolt:
9.5" ring gear 5,000 lb ft
10.5" ring gear 6,242 lb ft
11.5" ring gear 8,321 lb ft

@Bigburb3500 Isn't your rear axle some monster like 12" ring gear axle? I know the newer axles are even bigger than these I posted.

Also, this says 8.5" for the 10 bolt. Essentially, a 8.5" and 8.6" are the same. The ring gears/pinions are even interchangeable. They are commonly listed as 8.5/8.6.

You can even do some basic multiplication of your engine torque times transmission gearing and axle gearing to see what your theoretical torque is at your wheels (assuming no frictional losses).

I think so. I believe it’s the 11.5” ring gear but don’t quote me on that.