doninmedford

I have been searching all the 4l60e transmission information here, a big thank you to all that have contributed that, it's already helped me learn a lot. The information in the forum here spells out what needs to be done pretty clearly so no use to repeat all that, but when it's done I have no idea if OD is safe to use when pulling a car and trailer or not.

I read that towing in OD is not supposed to happen if towing over 4000 lbs in some factory towing literature. This is what my question is about. I have searched and get mixed answers. Some say as long as the transmission is not up and down shifting between 3rd and OD, some say no never means never. Some say if you build the trans and put in a billet 4th servo and other modifications it's fine. I noticed though a lot of "towing" 4l60e offered by various suppliers have nothing more exotic than the corvette servo and most of the basic updates suggested here. I have no Idea if a billet 4th servo is necessary to allow safe part throttle towing OD. I don't think WOT in OD will ever be needed towing, if your having to push that hard the trans will already be in a lower gear. With the mountains here in Oregon, I doubt I will need to use OD that often but knowing if it's safe or not once the rebuild is done would be helpful. I did change the rear differential to 4.11 and that's been the biggest towing help so far, but I do use OD more often now when not towing. With the 3.26 gears the transmission spent a lot of time in the lower gears just moving the van up and down hills.

07NBSChevy

iTrader: (1)

You can tow in OD, as long as its on a flat surface and the transmission will hold that gear. Once you get up to speed and are able to maintain that speed on a flat highway, go ahead and place in OD. If it shifts back and fourth than place in 3rd.

wht/73

My 04 1/2 ton Z71 Suburban's been pulling my 1700lb car trailer with dirbikes,quads and When I go to the track, my 3500+ Nova for 13yrs now.
When I tow, in OD, It's ALWAYS been in tow/haul mode.
Hills,flat didn't matter. 70/80 mph.
150K and counting.
Now that I said that it's going to puke on me!

coryforsenate

iTrader: (1)

wht/73, what sort of setup does your 4l60e have?

wht/73

Whatever GM put in it in 04.
3.73's and the "towing package"

07NBSChevy

iTrader: (1)

I have towed close to 8,000 lbs with mine through some steep grades and do this every 2 weeks when I take my travel trailer out. This is a list of my mods I have done specifically for towing. It started life out as a stock GM Crate 4x4 4L70E, 0-miles when installing mods. I also use the stock 1600-1800 Stall Converter, I really want to try the Circle-D 300mm 2400-2600 stall but am afraid it may affect my towing.

-Any Seals/Gaskets/O-Rings replaced were OEM GM Only
-Used Sonnax Vanes for the 13-Vane Pump and set at the Minimum Required Clearance (Tight Clearances)
-Transgo HD2 (C) Kit
-Transgo Hardened Separator Plate, drilled according to Transgo in conjunction with other items used for build.
-Transgo 700 PKH unbreakable pump rings (For 5,500+ RPM)
-FLT Billet 13-Vane Pump Rotor
-FLT Billet Overrun Piston
-GM Corvette Servo (I recommend this over Sonnax due to hard shifts when towing, great for street/strip though)
-GM Aluminum 1-2 Accumulator (plastic ones will crack)
-GM OEM Deep Filter
-Tru-Cool 40k Cooler
-Mag-Hytec Deep Trans Pan
-Sonnax 4th Gear Super Hold Dual Servo
-Sonnax Servo Release Check Valve
-Sonnax Pinless Forward Accumulator
-Sonnax 3-2 Control Valve Spring
-Sonnax O-ringed End Plugs (All Locations)
-Sonnax Accumulator Valve Train Kit, used Medium (White) Spring, 77777M-K
-Sonnax Torlon Check *****
-Sonnax Forward and Reverse Abuse Valve Kits
-Sonnax HD 2-3 Shift Valve
-Sonnax Line Pressure Booster Valve (Boost Valve), 4L60E-LB2
-Sonnax HD Pump Slide Spring (Maintains higher pump pressure above 5,500+ RPM)
-Sonnax Stator Support Shaft Assembly W/ Wide Bushings, 300mm Reluctor
-Sonnax TCC Apply Valve kit, PWM Style
-Sonnax TCC Aluminum Solenoid Snout with Anti-Drainback Valve
-Sonnax Wiring Harness Connector Reinforcement Bracket

For internals, I am using
-Sonnax Smart-Tech Input Housing kit with Billet 300mm Input Shaft
-Sonnax SmartShell/HD Reaction Shell
-Sonnax Billet Output Shaft for 4x4 Models
-Borg Warner Hi-Energy Clutches (Reverse Input, Overrun, Forward, Low Reverse, and 8-Clutch Setup for 3-4 Clutches)
-Borg Warner Hi-Energy Band (Not Kevlar, to aggressive for towing)
-Borg Warner HD Extra Wide 29-Element Dual Cage Forward Sprag/Low Roller Clutch
-Borg Warner Low/Reverse Sprag

I am partial to Borg Warner if you cant tell, never had good luck with Alto Clutches, their band did ok tho. I honestly do not know what else I could do to the trans to beef it up more. I think this may be it, next step would be the 4L80E or even a 6L80E.

My trans temps do not exceed 170 degree's when outside temp is around 115+ when not towing. I have never exceeded 205 degrees when towing. I use AC Delco Dexron VI and may switch over to Amsoil, I heard it works very well.

wht/73

Wow, you bought a new 70 and put all that in it to tow or am I misunderstanding ?
If so, that had to have cost a bundle. I get the pc of mind thing tho.
Wouldn't a 80E have been a more cost effective route?
Unless you really need the 3.06 1st
I can see doing some upgrades towing 8k that often with a travel trailer tho.
Kind of like towing a parachute!

wht/73

Don't do the 6 speed. I have it in my current work van and don't care for it over the old van with the 80E that weighed 7k+ with a pathetic 4.8

I never take this van out of od...because you can't with the 6spd.

07NBSChevy

iTrader: (1)

I picked up the 4L70E because my 4L60E grenaded itself. The trans is a special order only and someone ordered one at the dealership, and never picked it up. The dealership needed to get rid of it and I picked it up for $1,600, retail was $2,800 I think. Even a rebuilt 4L60E here locally was $1,200, So i Couldn't pass up the 70E. I used the Sonnax and Transgo parts I had in my blown 4l60E so I saved a bunch a money that way.

I drove it for awhile then added the rest. All the failures to my trans were at the drag strip and not actually towing. Since those upgrades she has been holding together nicely.

I personally like the 6L80E. My work is a 2010 5.3/6-Speed and we tow a 5,000lb trailer and I like the way it maintains the right RPM.

The main reason I didn't do a 4l80E was my truck is my daily driver and I didnt have time to mod a crossmember, re-pin the harness and take a chance with a used 4L80E only to find out it slips or something. I only had a day and a half to get it back up and going.

wht/73

I get the used thing.
I bought my 80 and handed it to my trans guy to get rebuilt.
I felt the same way.
The 5.3 is MUCH better then the 4.8 so the 6spd is probably better with it.
The 4.8 is useless and shouldn't be an option in a 3/4 work van.
Put the air on...and it only gets worse.
With the 80e and the 6spd.
I could probably beat it with my Suburban towing my car in a drag race.
So to the OP, I think he'd be fine towing in tow/haul mode.
Just don't drag race with it!

I have to say, my switch to an 80E is awesome, but reading all these horror stories about overdrive trans's blowing up has me nervous.
It makes me miss my th 350 and treemaster converter.
I had beat on it for 16yrs with only a rebuild and a shift kit.
3 engines, 4 torque converters.
50mph rolling burnouts in drive with no kickdown hook up and 1.45 60' off idle at the track.
ZERO issues. It now resides in my sons malibu replacing the pos 200.
I don't beat the 80 in OD.
3rd or below and we'll see how my 406 hit's it at the track.
It is very nice to drive on the freeway now tho!

07NBSChevy

iTrader: (1)

Yes, the 4L80E is an awesome brute of a transmission, even in stock form. I would of liked to have done the 4L80E swap but was somewhat concerned on how it would tow the weight with the higher/longer first gear ratio. The good thing is, you can just throw it in drive and not have to worry about your 3-4 clutches melting, The 80E will hold up well in OD. Though you should still place it in D3 (3rd) when beating on it.

I do not understand why they used the little 4.8L in the Express vans, even in the 3500 Cargo, the 6.0 should of been Standard. I see for the 2017 models they offer the 4.8, 6.0 and now the 2.8 Diesel from the Colorado. They used to have the 6.6 Duramax but looks like they decided to use the smaller 2.8L with the 8-Speed and 3.42 gearing. I bet the little 2.8L Duramax (181-Hp at 3,400 rpm. 369 lb-ft of torque at 2,000 rpm) would out perform the 4.8L.

doninmedford

Thank you for the information! I had posted three or four transmission related posts here two months ago and for some reason they kept getting deleted or not ever posted so I never came back after a few weeks. I started looking for more info on google and my old post popped up with info! On Gearhead-Efi a former GM transmission calibrator was very helpful. He said the 3rd gear when towing was mostly to get the pump volume up and this was important for reliability. He also recommended a 4l80e if towing more than 5000lbs for reliably. Unfortunately all this info came last week after I had already purchased most of the parts to rebuild the 4l60e. About 4000-6000 lbs is what I need to tow reliably so I am right there to need to swap the heavier transmission in.