Upgrade towing Capacity??

ace3166 · April 23, 2004

Have a '99 Suburban K1500 3:42 gears. Besides upgrading to the 3:73 gears what else can I do? Power programmer?? Suspension upgrade??

Not going to tow this weight on a regular basis, maybe 1 to 2 times a year for 400 miles or less.

PFarkas · April 23, 2004

No matter what you do, you will not be able to change the vehicle's Gross Combined Vehicle Weight rating. This rating comes from the factory. If you exceed it and get caught for any reason, it's all on you.

If you are not concerned with that, I would think that you should start with upgrading the brakes and work your way towards the engine, making a point not to skip the suspension.

What you propose is not cheap.

For a one or two time a year towing job, <400 miles, it would be cheaper for you to rent a pickup that's already able, mechanicly and legally, to do the job.

SilveradoWV · April 25, 2004

5000lbs seems really low to me for a Suburban?? In 99 were they still the old style?? If so it must have a 350, so the towing capacity loss must be in the suspension due to the large vehicles weight already??

Ben · April 25, 2004

[/b]1500 Suburbans are just streeeeetched 1500 Tahoe's. Same einge, tranny and diff. Same body but streeetched. Same base frame, just streeetched.

Known weak components of all GM 1500's is the auto tranny and diff.

The tow ratings of all manufacturers are based on "curb" weights. "Curb" weight is a stripper model with no options. Fine print on all towing guides, brochures, etc list one 150 lb driver and "necessary" options to tow.

This means that unless you have a stripper model, it has LESS tow rating or that "max trailer" weight is less because yours has options, which subtracts pound for pound. Usually around 500-800-1000 lbs worth. Things like: AC, Read AC/Heater, 2nd/3rd row seats, stereo, upgrade interior, roof rack, etc.

Typically 1500 Suburbans are only good for around 5,000 lb TTs. Any more and they risk burning up the auto tranny and/or diff.

Also, 1500's come with "P" rated tires, which are passenger tires, not truck tires. LT tires are recommended when towing heavy. P rated tires used in LT applications must be DE-RATED min 9% of their max weight rating, while kept at max pressure.

Larger dia tires reduce effective diff ratio same percentage difference in dia from OEM's 30".

Here's GM Towing Guide, 2001 version. Notice fine print that it's based on "curb" or "base" vehicle and one 150 lb driver.

ace3166 · April 25, 2004

Well I found a GM mechanic that will change both the front and rear gears to the 3:73's for $750 complete. Also I already have the LT tires, load range "E". Travel trailer is 6250lbs. Will just see how it pulls after that. If no good, I'll just trade it in for an Excursion. That way I can get a bigger travel trailer too. We'll see.......

steiny93 · April 25, 2004

If it were me,

I'd just hook up and see what happens.

Your only talking about 1500 lbs, take it easy and be careful.

Someone pulling 5000 lbs in your rig can be much more destructive then someone pulling 6500 lbs.

If its only 400 miles take it easy and save the cash for fuel.

my 2 cents

Shaners · April 25, 2004

Good idea swapping the gears... Make sure you have a good tranny cooler, and it would be a good idea to "add-a-leaf" to the rear suspension. I'd also use a weight distributing hitch.

Install a quality electric brake controller, because your "burb" doesn't have what it takes to whoa a load like that!!!

I'd also tow in "3" instead of OD.

redvett · April 25, 2004

[/b]1500 Suburbans are just streeeeetched 1500 Tahoe's. Same einge, tranny and diff. Same body but streeetched. Same base frame, just streeetched.

Known weak components of all GM 1500's is the auto tranny and diff.

The tow ratings of all manufacturers are based on "curb" weights. "Curb" weight is a stripper model with no options. Fine print on all towing guides, brochures, etc list one 150 lb driver and "necessary" options to tow.

This means that unless you have a stripper model, it has LESS tow rating or that "max trailer" weight is less because yours has options, which subtracts pound for pound. Usually around 500-800-1000 lbs worth. Things like: AC, Read AC/Heater, 2nd/3rd row seats, stereo, upgrade interior, roof rack, etc.

Typically 1500 Suburbans are only good for around 5,000 lb TTs. Any more and they risk burning up the auto tranny and/or diff.

Also, 1500's come with "P" rated tires, which are passenger tires, not truck tires. LT tires are recommended when towing heavy. P rated tires used in LT applications must be DE-RATED min 9% of their max weight rating, while kept at max pressure.

Larger dia tires reduce effective diff ratio same percentage difference in dia from OEM's 30".

Here's GM Towing Guide, 2001 version. Notice fine print that it's based on "curb" or "base" vehicle and one 150 lb driver.

Quote:1500 Suburbans are just streeeeetched 1500 Tahoe's. Same engine, tranny and diff. Same body but stretched. Same base frame, just stretched.

I will have to disagree with BEN, The Suburban is not a stretched Tahoe. #1 The Surburban has been around since the 1930's and #2 When i was involved (retired GM Engineering) in the Tahoe in 1995-6 it was all made out of a shorter Suburban. The Suburban was first @ #1 and the Tahoe is smaller and lighter.

robsawatsky · April 26, 2004

[/b]1500 Suburbans are just streeeeetched 1500 Tahoe's. Same einge, tranny and diff. Same body but streeetched. Same base frame, just streeetched.

Known weak components of all GM 1500's is the auto tranny and diff.

Quote:1500 Suburbans are just streeeeetched 1500 Tahoe's. Same engine, tranny and diff. Same body but stretched. Same base frame, just stretched.

I will have to disagree with BEN, The Suburban is not a stretched Tahoe. #1 The Surburban has been around since the 1930's and #2 When i was involved (retired GM Engineering) in the Tahoe in 1995-6 it was all made out of a shorter Suburban. The Suburban was first @ #1 and the Tahoe is smaller and lighter.

I'd have to agree with the negative on the "stretched" Tahoe = Suburban.

It's kind of like saying a 1500 extended-cab short-box is a stretched regular-cab short-box; or a 1500 extended-cab long-box is a stretched regular-cab short-box.

Well, they are longer but the frames and bodies aren't just the smaller versions cut apart and a piece welded in the middle, they're individually designed and fabricated.

The reality is that the Suburban 1500 has the same basic drivetrain as a 1500 pickup (as does the Tahoe). But, due to the body, it has a bit more starting weight than the pickup, which cuts into towing capacity. The 3.73 gears in the axles will be a definite improvement. The 3.42 gears were notorious for not standing up to much of a load.

The 4L60E should be OK if not abused and kept nice and cool but still is substantially weaker than the 4L80E found in the 2500's.