Recommended 4L80E HD/Towing Mods?

[Duncan Sterling]

Hello All,

I've got a '91 R2500 Suburban (fleet model, ex NYC fire truck) with an NA J motor and a first year 4L80E (no tow/haul mode, and just a regular 'P R D 2 1' shift indicator), and a 3.73 rear end. Roughly 126K on the clock.

If you believe the factory VIN decoder, this truck is rated for #9000, which says to me about #6300 max towing, realistically.

I've just picked up a #6000 boat which I'll be towing this summer. So aside from the obvious engine mod questions (I've already posted in the 6.2 forum, http://www.thedieselpageforums.com/t...d.php?t=26481), I've got some questions about my 4L80E, and what I need to do to prep it for hauling #6000 on a regular basis.

1) Do I need a shift kit? If so, whose? Transgo? B & M? And which kit (if they offer more than one)?

2) Should I replace the factory trans cooler with a larger model and a dedicated fan?

3) Do I need to get a higher capacity, finned oil pan?

4) Should I pick up an electronic shift controller to add a tow/haul mode to this trans? If so, whose?

5) I'm thinking a trans oil temp gauge is a must here, so I don't fry this thing, right? If so any recommendations?

What else might I be missing here?

TIA for all replies,

--Duncan

[rustyk]

I have an HD (rebuild) 4L80E in my motorhome. I did replace the pan with one from Mag HyTech http://www.mag-hytec.com/Transmission_pans.htm

and it helped with cooling - partly because it increased the capacity. My motorhome generally runs at 16 K lbs.

A transmission temp gage is worthwhile, IMO.

[DA BIG ONE]

There are problem areas in the older 4L80e's which can be identified through folowing site; http://www.transhardparts.com/

Sonnex is the #1 upgrade for all transmissions w/issues from factory.

A quality bullet proof HD off road 4L80e can get costly quick, if truck is keeper then the $$$$ is worth it.

[carco]

If you need a good replacement @ a good price check Jasper. We have very few warranty problems. For a very good production transmission with an excellent warranty find Jasper Engines and Transmissions on the web. Trans warranty is 3 yeras 75000 miles most applications. Jasper updates to all the latest factory specs and also works with several OEM's to improve life of their products.

[DickWells]

My 95 Suburban came with the large factory cooler. I put on a deep finned pan, but I never thought that I needed it. I did put 3 gages in a pillar pod. A good idea, having a transmission temp gage.
I towed around 6000 lbs for maybe 60 K, before I extended the tongue on my trailer and added about 1200 lbs to it, in the process. I put on another 40 K after that and never saw more than 230 deg temp. Usually saw less than 180. But, I did have that big cooler up front, so I don't know what to say about your rig, except to put a big cooler up there and a gage in the dash. Pretty good idea to change and flush the fluid. With these few things, I bet you would be good to go.
DW

[TJ Moose]

Next tranny fluid change - put in synthetic too. It'll give you another 40 so degrees of heat tolerance to the fluid if you heat it up.

[Craig M]

I think the Synthetic ATF will be one of the best things you can do. Mobil 1 or Amsoil come to one mind. $120 of Mobil 1 will go a long way to helping your transmission. Increased capacity of the ATF cannot hurt. The 4 quart pans add about 25% more volume to the system. Have yet to see any real data on aluminum pans vs steel pans in relation to ATF temperatures.