"Double down or fold" - Part 2 ...

[Stryder106]

Mine came stock with 4.10s. I'm running 4.88s with 35" tires. Whatever shop refused the frontend re-gear - find another shop - it isn't that difficult. With the headers, gears, rerouted exhaust, S&B CAI tube with Sealed box, Superchips tune - I make most of my torque at 2200rpm now (rather than the stock 4600rpm). Also - the Flashpaq tuner corrects for tire size and gearing and reclaibrates your speedo based on what you select. At 64mph I'm doing about 2100rpm.

 

[ClovisMan]

Around my parts, there are literally hundreds of GMT800 Burbs and Tahoes in the Boneyards. You can probably grab a front and rear diff from one with 4.10s already installed for $100 each. Then it only costs you labor for installing them. It can be done in your driveway and the only specialty tool you need is the torsion bar unloader tool.

 

[Buddha.]

Around my parts, there are literally hundreds of GMT800 Burbs and Tahoes in the Boneyards. You can probably grab a front and rear diff from one with 4.10s already installed for $100 each. Then it only costs you labor for installing them. It can be done in your driveway and the only specialty tool you need is the torsion bar unloader tool.

+1

If you separate at the lower ball joint and lower with a floor jack you don’t need the tool.

 

[Martinjmpr]

Minor update - still running strong on the new transmission. We went on another multi-pass trip with the trailer, this time the trailer was "wet" with 30 gallons (~250lbs) of fresh water on board (but with no Kayaks and no bicycles on board so in terms of weight, probably a wash.)

The one thing I did differently (that I probably should have been doing all along) is that I kept the truck in 3 rather than D, to keep it out of OD. It seemed to handle the hills better (didn't run out of momentum as quickly on 3 as it did on OD) and surprisingly, my MPG actually went up a tick.

I don't recall the Chevy owners manual advising drivers to tow in 3 rather than D. I know on my previous vehicle (2007 4runner), Toyota specifically DID advise that the vehicle should be in 4 rather than D (A740 5 speed auto) when towing.

Trans temps were great. Highest temp while towing was 159 climbing a slow pass. Actually, the highest trans temp I saw all weekend was 168 and it wasn't even hooked up to the trailer, that was waiting in the mile-long line at the entrance of Great Sand Dunes National Park in Southern Colorado.

 

[Ducky's Dad]

On that trans, does leaving it in 3 prevent the torque convertor from locking?

 

[rayra]

I'll have to go dig up my manual but I'm pretty sure the 'Tow Mode' instructions say to put it in 3rd when that mode is switched on..

/might have been your trouble all along and why you've bogged so bad on steep inclines, leaving it in OD / 4th and with the torque converter locked up. That and holding it at high RPMs trying to strain upward in speed until the vehicle will kick back up a gear, too.

eta

went and dug up my manual, pgs 4-56,4-57, "You can tow in DRIVE (D). You may want to shift the transmission to THIRD (3) or, if necessary, a lower gear selection if the transmission shifts too often (e.g. under heavy loads and/or hilly conditions" [emphasis added]

and there's a bit about Tow Mode meant to really help in town, heavy loads, and when you are operating in a config where GCWR is over 75% of rating. Which for our 1500 Subs with 5.3L and 3.73 gears is a max trailer wt of 7700# and GCWR of 13,000#. And with 4.10 is 8700# and 14000.

Our factory Class III hitches have a data plate that says GCWR of 12,000#, IIRC.

So I'd say with your stout trailer setup and steep protracted grades you should probably by putting it in 3rd, as things are rigged right now.

I've towed cheap ski boats, pair of jetskis, 14' tandem axle enclosed uhaul crammed full of household goods, equipment trailers, a few thousand pounds of slumpstone block on an open rental trailer over the 4000' passes on the north side of L.A. and into the Sierras with our '99 and '05 Tahoes and the heavier stuff always in Tow Mode and in 3rd on the mountain grades and never had any bogging down troubles. In fact the tandem axle uhaul towed like it wasn't even there. But never at the much higher altitudes that Martin routinely drives.

I'm still thinking a tuneup and some sort of variable tuning ability to temporarily boost engine performance on the hard grades - as well as keeping it in 3rd in Tow Mode - ought to solve his bogging down issues. And thusly the potential harm to the new replacement trans.