1999 transmission and towing question

AdamG · May 25, 2004

I am considering trading in my 99 sonoma on a 99 1500 I found at a mega dealership tonight.

I went to carsurvey.org to get a basic idea and found alot of negative comments about the trans.

I am also looking to buy a 25ft 5th wheel (about 4k pounds) so I am curious as to the specs of towing from a 5.3 w/auto trans on a 1500 w/65k miles.

Oh yeah, and average mileage? I'm guessing 15-18 on highway, how far off am I?

1999 CHEVROLET SILVERADO - Stock #XE181321

the link

Cop_Dodger · May 25, 2004

It's got the same transmission you have in your current truck.

ShadowJ · May 25, 2004

I have a 99 Silverado with 76,000 miles on it and I am now replacing the valve body for the transmission. It has the 4L60E. Problem is shifting from 3rd to 4th. Its starting to slip. Not a big deal really, I am getting a reman valve body from GMPARTSDIRECT.com and I am putting in a TransGo shift improver kit to keep this from happening again. All totaled I am spending under 400 dollars and doing the work myself. Its a bit of a pain but I still wouldn't trade my truck for any other!

Good luck

Ben · May 26, 2004

Any 1500 towing above 4K lbs is on the heavy side. Bigger the 1500 TV, the higher loading on the 4L60E.

Also the diff is weak link for towing. 10 bolt and 12 bolt both weak.

Not that they are "bad" comopnents. They are very good, but undersized for todays towing loads.

On top of that, things got worse for them with 2 other things. 1) larger tires, which effectly reduces the diff ratio. Standard pickup truck tire dia for a 1500 used to be approx 27 inch dia, now it's 30 inch dia. Even larger on some after market. 2) Heavier everything. From the options put into the TV to the TT.

If your fiver truely weighs in at 4K lbs, it should be fine **IF** the 1500 has 30" dia tires, min 3.73 diff ratio (higher numeric the better for towing), tow package, flush fluids often and no suspension lift (reduces HP delivered to pavement...higher U-Joint angles).

Think you maybe using the sales baited: "DRY" weight, which is the stripper model with no options. No spare, no propane, no microwave, no TV, no liquids, no upgraded interior, etc. Plus no cargo (food, water, drinks, fire wood, luggage, clothes, gold clubs, bicycles, lawn chair, etc).

Check your PIN & hitch weight plus any cargo you'll load in the TV, as a 1500 with this sized TT will quickly exceed it's rear GAWR.

Think you'll need a 2500, but don't really know till you have the fiver weight (not the "dry" weight but the true weight).

intruder217 · May 26, 2004

Just returned from my first long distance haul. The truck is a 99 Suburban with the 5.7 Vortec and the 4L60E, axle is the 3.42 and the truck has all the "heavy duty" tow options. I pull a steel two horse trailer that is extra tall and extra wide. It weighs 2600 lbs empty. I put a 1000 pound horse in it plus 4 bales of hay. In the truck were two adults, tack and gear for four days. I was skeptical about the 4L60E and was prepared to have to hold it down into 3 to get any performance. Turns out the transmission knows how to shift, I left it in OD, and didn't shift up or down excessively. Engine temperature stayed in its normal position, we even ran the AC as it was a warm humid day. We went about 180 miles. Got close to 11 MPG. Oh, BTW, it has a Westers 87/91 dual tune. I did not tow before the Westers so I cannot say how it was before.