700r4 dies, should I rebuild or replace with a different kind of transmission

Hello All! I'm new here, and could use your help.



I have a 1988 Chevy G30 Cargo van that I use for personal cargo transportation.


I am a big fan of buying old industrial and commercial vehicles and souping them up. However, I have only a moderate level of transmission and drivetrain knowledge. This Van has a 700r4 in it that was recently rebuild by one of my dads friends. Well, I overfilled the tranny by accident, because i was in a hurry (I live on the texas coast, and was evacuating from hurricane rita) and then when i got to about 70 mph on the highway ( about the ONLY time i got to go that fast with the rest of the highway looking like a giant tailgate party) BOOM, and then it failed to go into gear. So I stopped, and fluid was pouring out of the overfill vent on the top of the tranny. I let that drain, and tried to go again. To my suprise, ,the transmission still worked, but only went up to peak of second gear and then lost the grip. I'm thinking that i blew the pump seal and now it wont get the pressure to shift into 3rd gear.

Anyway, I know enough to rebuild this tranny, so i want have to pay labor, just parts. But my skills with transmissions are only some general knowledge and the common sense that a kid would need to build a lego set. Nonethelless I can do it because i've done it before and did a good job if i do say so myself. I just make sure I do the research before i begin the project.


SO, Do I rebuild this tranny, or could i switch to a stronger tranny like the 4L80E (or the non-electronic version, whatever that is) or even the Allison, if possible. From what I understand the allison is pretty much the strongest you can buy and I know you can buy aftermarket, standalone computers for them if needed but i guess the question is, will it fit my bellhousing and will it fir the chassis?


What do you think?


Thanks

 

Well, I'm a moron. Um, the allisons only bolt up to the 8.1L and 6.6L Diesel Engines.

Nevermind



But the 4L80E (Im guessing the electronic version of the TH 400) is still a viable option.


Update: Well it looks like the engine is shot too son of a *****
I mean it runs fine but will pretty much need a complete overhaul to pass emmissions. That means this little loan i got to buy this vehicle was completely used on a vehicle which now needs an engine rebuild AND Transmission rebuild.

Im guessing probably a good $500 for the tranny rebuild (if I do myself) and probably a good $1500 for the engine because im sure I'll probably have it bored and get all new pistons and rings and such.

This does me alot of good because I have $0

I guess i gotta do this paycheck to paycheck



*sigh*

 

hate to say it but time to find a new ride from the sounds of it.

 

If you can do the trans yourself then you can save a ton of cash. Ive rebuilt mine in my truck that I race 22 times...no wait...I quit counting after 22 rebuilds. Anyways, a quality kit (I use transtar kits) will run you about $140. A new torque converter will run you about 200 bucks depending on who you get it from (I use DAACO).

With that being said a 700 isnt a build it with your eyes closed TH350 so definately do your research as well as pick up an ATSG manual (ebay ~$15) for the year 700 you have and follow it to the letter. You'll need some bushing drivers to install the bushings in the pump and case and a piston return spring compressor. If youre handy and have access to a lathe you can make the bushing drivers for practically nothing and the piston return spring compressor can be made with some allthread, few nuts/bolts/washers, and some scrap steel.

An 80E retrofit is going to be pricey...REALLY pricey. Ive retrofitted my truck with the 80E after I got tired of blowing up 700s and spent way more than I like to admit doing the retrofit but then again its nice to get more than one 1/4 mile drag strip pass in before having to rebuild the trans like I was doing with the 700. Off the top of my head I spent 800 bucks for the trans (96 model from a salvage yard), 1000 for a torque converter, 1400 for the controller to run the trans, and 400 for the rebuilt kit even though the trans only had 40k miles when I got it (figured Id rebuild it since I had it on the work bench ). However, once you do the math at what it cost to rebuild the 700 well over 20 times compared to no failures (yet) with the 80E Im actually saving money....sorta. In your case (unless youre drag racing your van ) Id say a rebuild of the 700R4 trans will make more sense from a cost stand point.

As for the engine... I cant help you there really since I refuse to work on vans. I did a R&R on a chevy van once due to the engine needing rebuilt and havent touched one since.

 

Th700R4's are a lot more difficult to build than a Th350 or 400, from what I have been told from numerous people. I wouldn't risk it, I'd have a shop rebuild it. IF you rebuild it, and it works fine then you saved a few bucks....you mess up and it doesn't work right....you are out your time, the money you spent on the rebuild kit that might or might not still be good, plus what it costs to have a shop do it the second time.

I'm not a guy that likes to "gamble" with stuff like that. Especially if this is some sort of commercial vehicle that is making money for you. It needs to get back on the road if it is a money maker.