tranny swaps

[Texas_Hale]

I want to replace my 700R4 in my Suburban with a manual 5 or 6 speed, or perhaps an allison tranny. Do you have any recommendations as to what tranny would fit? I forget which transfer case I have, it's the chain driven front output, that is supposed to be bullet proof. Thanks!

[CleviteKid]

Hey Rusty:

If you are considering the Allison, then you must not have anything against the concept of an automatic transmission in your truck.

The Allison needs a computer that talks to a Duramax engine computer. Don't count on putting an Allison in.

The NV4500 fits, and has been installed as an upgrade by some of our members.

The 700R4 will work just fine behind a diesel, if built correctly by a quality shop. I just had a newly rebuilt 700R4 put in my truck, and it works great. Look at the 6.2L Forum for discussions of 700R4 trannies. The consensus is to stay away from Raptor transmissions.

Dr. Lee

[Texas_Hale]

Well, actually, I haven't had good luck with 700R4s. Rusty (which is my pickup) has had his 700R4 rebuilt with a shift kit and a cooler. It has less than 10K miles on it, and it's slipping between shifts. My Suburban which is in question has a 700R4 in it now, but the pump seal is gone and tranny fluid gushes out when its running. I would LIKE to have an automatic, but I am leary of them now. Of course the tranny was built by a local shop and here in El Paso no one is interested in providing quality. Every job is sure to be the crappiest job that can be done. How many gears does the NV400 have? Is it a 5 speed?

Thanks a lot, Mike

[britannic]

The 700R4 is very sensitive to the TV cable set up and if not adjusted to the correct base pressure will self destruct very rapidly (check out www.tvmadeez.com).

Here is an excellent 700R4 forum: 700R4 Discussion

Properly built, maintained and adjusted, 100,000-230,000 plus miles can be realized. The key is in the upgrades. A shift kit is only a tiny piece of the story. I have a pressure gauge permanently plumbed into my 700R4 system pressure along with a temp. gauge to monitor it's health.

I won't drive it with less than 75psi at idle in drive with an immediate rise to 125psi at 1250rpm as I pull away. Anything less results in slippage.

Another hot tip, change the tranny fluid at 20,000 miles (use Dextron III) and get an auxiliary cooler to extend the life by keeping average temps under 160F.

It may be more expensive to convert to stick shift than installing something like this:

Extreme Duty Street/Strip 700R4
High Performance Street 700R4
BowTie Radical Street/Strip 700R4

[ 08-24-2003, 11:30 PM: Message edited by: britannic ]

[Texas_Hale]

I am running Amsoil synthetic. They say that's what the Border Patrol uses in their rigs. I did have a cooler installed as well. TV Cable has been set.

[britannic]

Temporarily install a 0-350psi pressure gauge into the system pressure tap above the selector clevis and check for a minimum of 75psi in drive @ idle. Then see what pressures are recorded for 750, 1000, 1250 and 1500rpm in drive with the brakes chocked.

Here's a list of recommended pressures for a stock system (the first number is minimum TV and the second at max TV):

P: 75-85 166-203
R: 100-140 180-340
N: 75-85 166-203
OD: 75-85 166-203
3: 75-85 166-203
2: 160-245 160-295
1: 160-245 160-295

[ 08-25-2003, 09:48 AM: Message edited by: britannic ]

[NH2112]

Consider a 4L80E with stand-alone computer, that monster will definitely handle the torque.

If you decide to drop your Sub's 700R4 to replace the pump seal, carefully inspect the torque converter where the pump drive meets the housing. My 700R4's converter was cracked here and was slinging fluid like no tomorrow.

I ended up swapping in an SM465 4-speed, and it was a very simple swap. Get a donor truck, or at least get all the parts you'll need from one truck, and it'll cost quite a bit less than a built 700R4. The NVG4500 is a little harder from what I've been told because it was never offered in our body style trucks and might require a bit of trans tunnel reshaping (or a body lift.)

[Texas_Hale]

Thanks Phil. Actually, I don't know 100% that it is my pump seal, it could very well be the tourque converter, I will inspect it real well. Do you think that I could get away with just doing that much on the tranny? What about the other gaskets and seals?

Also, that SM 465, is an overdrive unit? I really would like more gears acutally, even on an automatic.

[G. Gearloose]

Then you might not like the 465. 465 is a 4 speed. 1:1 top gear. Only three of which you use normally.
You could use first gear, high gears and big tires to get some OD effect, but the step between gears is large, and first gear in not synced i believe..
but built like a iron $hithouse, no doubt.

IF you don't mind the engine singing at high rpms, its great. Some of the best milage I got was 22 mpg on a 4.10 K20 with 235R75 tires..

[7dcuda]

I used a TH-350 in my Sub and have about 130k miles with out a problem. You'll need a kit that has an extension on the rear of the tranny, new gear selectors for the dash, a dipstick tube along with the kickdown/TV cable. I don't remember where the Conversion parts came from but this swap was one choice for the gas vehicles. I wouldn't think it would take to much time to find one. As I recall I spent about 650 for a rebuild kit converter and flex plate intalled by me about eight years ago.

[britannic]

You'll really miss that .70 OD ratio. If the 700R4 has the requisite upgrades, transmission cooling and the TV is properly adjusted, it will last and last. Other members have reported in excess of 100K. Check out 700R4 Forums.

Also BowTie Overdrive Transmissions have very nicely specified 700R4s and an excellent website.