Ok 6.2 Tranny Guys

[ZZ]

Would someone list all of the GM automatic transmissions that will bolt up to a 6.2L and run in a 1990 GMC Sierra 1500 XC 4X4?

I'm still running the screwed up 700R4 that the local tranny shop rebuilt for me. It works perfectly here in town, but I lose overdrive & the lockup TC on the highway. The warranty went out in Dec. They evidently rebuilt one out of a gasser and the pressures are wrong. They can't locate a 700R4 case out of a diesel and I'm tired of not being able to drive my truck much distance on the road.

I don't have the funds to really do this thing right. I can only get about a $1,000 right now. I asked the shop to quote me an installed rebuilt TH400. They are supposed to let me know Monday.

I wish a little TH200 would fit. I had several of them and never had a problem with them in my 5.7 Diesel car days. My truck is used more like a car than a truck.

[jbell]

You want a th-400? I have everything you need. I pulled out my th400 and put in a 700r4 from another diesel burb. It works flawlessly.

I have the original metal vacuum line for the shift modulator, the flexplate (they're different 700r4 vs th400) the torque converter, and the trans. I was told that due to my burb being a 'trailer special' that this trans may be known as a th475 (heavier duty th400??)

Anyway, it's yours cheap if you want it, and want to pay to have it shipped from KS.

Let me know.

[ZZ]

Thanks, but I'm afraid the shipping would be too cost prohibitive. You could check though. My Zip code is 63857

[jbell]

The cheapest fix, is to make your 700r4 work right.
My guess is that the governor springs / weights are all wrong.

I'd head to my local gm parts counter, make them look up a diesel pickup with a 700r4, and order the correct springs/weights. The valve bodies shouldn't be much different gasser vs. diesel.

Pressure is key, and adjustment of the TV cable is a must. I'd hook up a pressure gauge and a length of hose to the pessure port of the 700r, and go driving. If the pressures are wrong -- it's most likely either governor or tv cable.

You can also tell just sitting idling, if you pull the tv cable, pressure should go up. Somewhere I have all of the pressure stuff written down -- I'll go look. Also you should NEVER loose TC lockup. All you need is +12. If you have the computer, Throttle position sensor, etc... lose them. run +12 directly to trans (through a break interrupt switch) and have a defeat switch in the cab for city driving. Depending on the internal wiring of the 700r, you can put an idiot light in the cab to indicate good lockup.

[Dominique]

Check out this 700r4 on ebay item #7919344053 I'm getting one for my burb.

[jbell]

I've talked with lou -- good guy. MAKE SURE he knows you're talking a diesel setup, don't just bid on the ebay listing. He'll add the beast sun shell, and a couple other things. He'll also set up the govenor different. Ask him to make it lockup in 3 or 4 only. Also have him wire it for 3 wires (3rd wire is for your lockup light in the cab) 2nd gear is the the gear that typically gets ripped out of a 700r4, and gm made it lock in 2,3,4. Also, there is a police cruiser caprice torque converter (added $$$) that is well worth it.

All in all, lou's a good guy, I trust his tranny's. Search this site, you'll see report after report of other 'bulletproof' 700r4's that can't make it out of the parking lot.

[mhagie]

I have an extra 700R4 but I don't think you need one by the description you give.
First you say it works in town,does that mean you get lockup and od or just od?
You should have three shifts plus lock-up which feels like a shift, if you have all this in town and not on highway I can't believe it is anything but electrical.
Merle

[ZZ]

With the Questions coming up here I'm going to paste a post I made a couple of months ago about these problems...


As some of you know, I have had 700R4 problems now for over a year. This started in 12/03 when the original went out. I was in a big hurry to get it back on the road with my job at the time. The tranny shop offered to rebuild a gasser 700R4 with a new diesel TC. The warranty for it was 1 year. When I got it back it shifted too late and too hard for my liking. The only way that they got it to my liking was to somehow modify the governor. It worked well here in town, but it was squirrley shifting up & down between 3rd & OD on the road between 32 - 45 and then the TC wouldn't lockup after a few highway miles. It lasted like this for about 7 months and then started slipping.

The shop worked it some in June and then they did a complete warranty rebuild last July. They claimed that they put in a new low stall diesel TC. They used the same modified governor this time. They also wired the TC lock direct to ground to bypass the electronics. It seemed a lot better, but it is still shifting squirrelly between 3rd & OD on the highway.

The warranty expired 12/18/04 and then it went crazy earlier this month. One day I was on the road at 65 /w cruise and it dropped down to 3rd for no reason. It went back to working again after it was parked for awhile.

[jbell]

My 2c (didn't know about earlier posts) is that the govenor springs/weights are the issue. Shift points are a balance of pump pressures vs. govenor springs/weights. I really believe that if you get the original gm diesel springs/weights, and then tune the tv cable (pressure) to shift at the appropriate time -- you'll be good.

Too weak of springs / low pressures will give very erratic shifts. Too strong of springs / high pressure will result it very harsh / late shifts. My guess is that they went from stock gasser springs to something that was too weak, and consequently too low of pressure to balance out shift points.

If anyone knows 700r4's it's gm -- stick close to their oem specs on governor.


I went through a large number of these things in the 80's -- always considered them junk. However gm, and the rest of us have learned, and they can be good.

[garysleeman]

I've been running a gasser 700r4 behind my 6.2 for a couple of years (actually my truck was a gasser and I swapped in the 6.2). I had problems with the lock-up and shift points. I read many 700r4 articles (read Dr. Lee's) and looked at many web sites. I found my shift problems were related to the TC cable adjustment and the only way I got it right was to drop the pan and do a visual check. I purchased a lock-up kit from bowtie overdrives and that solved my lock-up problems. I am running without a computer and I think that is the only way to go with a 700r4.
Good Luck.

[ZZ]

Does any of the TH350 or TH400's use the locking torque covertor?

[Robyn]

The 350 C had a lockup but you will need an adapter to put it in place of the 700
As was mentioned earlier the 700 is the only way to fly. The 700 is not hard to rebuild but does need some attention to details. A good transgo shift kit is an esential must have. The TV cable adjustment is no big deal. Slide the adjustment slider back toward the firewall all the way and then mash the throttle all the way to the floor. The cable will self adjust. To tell if you are good to go drive the truck at light throttle and as soon as it shifts from 1st to 2nd mash it hard and it should drop to 1st again. If it does not you need more TV pressure. If you are having slipping problems the tranny is already most likely toast. The shift point issue is a matter of valve body springs and the governor. You can get a new diesel governor at the GM parts counter and simply put it in. The round cover on the side of the tranny is a friction fit and will pop off with a few taps on a screw drive placed at its edge. Pull the old governor out and stick in the new one. Put the cover back onmaking sure the seal is ok and you are done.
With the symptoms you are describing though your 700 is in trouble and needs to be benched and gone through. I rebuilt mine back in December and did the works to it. I bought most of the good parts off of ebay. If you have never done a 700 dont panic if you can get the tranny out you have got the hard part done. You can do a real nice job yourself on this box for about $700
get a good 700 tranny book and this will get you through the basics of tear down and rebuild. Order a complete rebuild kit and this will get you all the hard parts. Order a transgo shift kit its called the 2-3 kit. Follow the instructions to the letter and your little 700 will put a smile on your face. If your oils is burnt smelling you will need to flush the convertor. Alway put a return line filter in the cooler circuit to catch any junk coming back from the cooler. If you dont know which line is the return disconnect both and see which one does not have oil coming out when you start the rig. Just put a hose on them both and stick them in a bucket and have a helper start the engine (tranny in N) shut off quick as oil comes fast. If your oil is not to badly contaminated you can just drain the convertor by placing hub down over a bucket and let sit overnight.
Dont be scared by all the talk of how complex a 700 is cause it BS just lay everything out in order as you take it apart. place the valve body aside and do it last after you have the box back together. You will needa puller to get the front end (pump) out but a good garden variety puller and a c clamp to hold the jaws on the stator support will work. The book will call for some seal installers, yes you will need these as if you dont use them you will ruin some lip seals and the trany will not work right. Snap ring pliers are a must but most tool boxes have a couple pairs floating around. Just be careful and your tranny will work fine,
Let me know if I can help and I will talk you through this thing. Be happy to do a phone rebuild with you. :0)
Robyn

[ZZ]

Thanks for the offer, but I am physically unable to try to work on it myself.

I think I have narrowed the problem down a bit. I forgot about hooking up a toggle switch for the locking TC last year. If I leave it turned off the erratic shifing between 3rd & OD stops at 35 - 45 mph and it will stay in OD on the highway. Otherwise it will drop back down to 3rd after 10 to 15 miles if the switch is on.

I also experimented with TCC cable all through the length of the adjustment. It still has these problems if the TC is powered at highway speeds.

[ZZ]

I still don't understand why the shifting problems go away with the TC lock turned off.

Is the tranny apt to get too hot with the TCC lock off if I drive about 60 mph or lower? I do have a guage I can watch. I also have a mid-duty cooler installed.

[ZZ]

I was hoping to get a final response on the last question I asked in the last post above this one.

This will be last question about this problem

[Brianlar]

The only way to be sure is to drive it, and watch the gauge. The common logic is that it will run cooker with the lock engaged. My 700 is also not locking up. I am trying to figure out how to wire a direct switch to engage it.

[ZZ]

I was thinking the same thing about driving it and watching it. I just wanted to make sure it isn't a guaranteed burnout.

I know the best thing to do is to have it fixed right, but funds are not available as of now.

I'm going to try to get by with it till October. We'll have my wife's car bank note paid and then I plan on getting for me a late 90's 6.5 and then my wife wants to bounce back & forth to work in this truck.