where to find good donor for 700R4?

[63frankintruck]

I have read lots of info on putting a 700R4 in 63 C10 pick ups, but have not stumbled where to start looking for a donor?
Is it only in the 83-87 C10 trucks?
I want a good strong trans. Just wondering were to start looking.
Thanks for any help in advance.

[68c10owner]

Try to find a 1987-up trans. The earlier ones have a smaller input shaft and have weaker internals than the later ones. And you have to be careful what you pull it from because some vehicles had a electronic speedo and might not have a mechanical speedo drive. This can be converted but its a added expense that can be avoided. There are several places that sell the 700R4 outright so that might be a option for you.

[63frankintruck]

87and up to what? What year did they go to the electronic version of OD?

[D13]

Up to 93 MAY be cable. 91 up were electronic speedo. Also came in cars. 87 up had many improvements, cases with a K cast in are considered the best.
Unles you rebuild these yourself, it might be easiest to pick up a cmplete unit from TCI/Monster/Phoenix etc. Any used one is pretty much a crap shoot. Most have been rebuilt at some point in their life (remeber these are 20 years old!) and it's hard to tell what internals they may have. Stay away from V6 units (less torque capability) and be aware that 2.8 S10 units have a different bell housing that doesn't bolt up, 2wd and 4wd have same cases but different outputs.
Trans also came in Caprices, in 350 powered cop cars in the 80's and all once they went to the round body. Also Vettes and Camaros.

[Bigdav160]

The 700R4 was available in trucks, vans, Camaro, Corvette and Caprice as long as it had a Chevrolet engine. In many xases it was the "optional" transmission. 3 speeds were still common. Most of the big cars didn't get a Chevrolet engine until the middle 1980's instead they had Oldsmobile/200-4R engine transmissions.

Electronic controls didn't happen until 1993 (trucks) and 1994 in cars.

The earlier models don't bother me. There's not as much difference as people like to believe.

[Clyde65]

Give a holler to Clinebarger here on the forum. He works at Larrys Speed in Ft Worth and do engine swaps down to oil changes, including transmissions. They will treat you right and you will get some great quality.


http://larrysspeedcustom.com/

[jjzepplin]

I bought mine from a junk yard as a core for $50- Bought a B&M rebuild/upgrade kit for $300 and a $20 video. 1989 truck trans. I took apart the earlier one I had (1984) and was talking to the B&M tech and he suggested I start with the later version. My first trans rebuild and all is still good 14 or so years later. I really got a good knowledge of how these things work by building it myself and made the setup easy. Cable setup is crucial to longevity in these. I have the vacuum style lockup kit OH! And be sure to get a GOOD converter. My first TCI exploded and had to get a custom one.

[68c10owner]

Originally Posted by Bigdav160

The earlier models don't bother me. There's not as much difference as people like to believe.

GM decided there was good cause for a change but please enlighten us as to why there isn't much difference.

[68c10owner]

Originally Posted by 63frankintruck

87and up to what? What year did they go to the electronic version of OD?

87 and up transmission. As mentioned they came in many vehicles, not just trucks. Starting with a 1987 and newer unit is your best bet.

[Bigdav160]

Originally Posted by 68c10owner

GM decided there was good cause for a change but please enlighten us as to why there isn't much difference.

Off the top of my head, Up through '84 the input shaft was the same size as the 200-4R. The biggest improvement in the early models was a simplified forward sprag and improvements to the pump to make it more reliable.
1986 the low roller was strengthened from the previous TH350 piece it was using.

1987 Hydramatic redesigned the case to accept a forward accumulator system to cushion shock going into drive. Some one-piece seals replaced scarf cut seal previously used and the pump vane count was increased again.

There were other minor changes made through the years. Many of the changes retrofit to earlier models. Some items, do not retrofit backwards but I don't see them as a big deal.

[68c10owner]

Originally Posted by Bigdav160

Off the top of my head, Up through '84 the input shaft was the same size as the 200-4R. The biggest improvement in the early models was a simplified forward sprag and improvements to the pump to make it more reliable.
1986 the low roller was strengthened from the previous TH350 piece it was using.

1987 Hydramatic redesigned the case to accept a forward accumulator system to cushion shock going into drive. Some one-piece seals replaced scarf cut seal previously used and the pump vane count was increased again.

There were other minor changes made through the years. Many of the changes retrofit to earlier models. Some items, do not retrofit backwards but I don't see them as a big deal.

They used a 27 spline input shaft until 1986, after that was a 30 spline input shaft. Every thing you mentioned makes the 1987-up models that much better because every one of those increased the performance of the transmission. There is no reason to use a 81-86 trans for any kind of a performance build unless thats what you have and you do the upgrades. My stock 305 killed a stock 1985 700R4 so I would think a performance application would have a much shorter life. Mine was rebuilt with 87-up internals. Not only are they stronger but a lot of the rebuild parts arent available for the early transmissions. The way I see it is if they arent a "big difference" to the performance of the transmission GM would never have changed it.

[63frankintruck]

Ok well I have chance to purchase a 84 C10 with "supposedly rebuilt" trans
Guess it's a crap shoot

[68c10owner]

Originally Posted by 63frankintruck

Ok well I have chance to purchase a 84 C10 with "supposedly rebuilt" trans
Guess it's a crap shoot

There is nothing wrong with the early units but I would not use them in stock form for any performance. If its rebuilt it should be fine. I bought my 85 GMC in Sept and in Early November I was having the tranny rebuilt. I called several shops who told me the same thing, the early ones are harder to find parts for so they just upgrade them to the 87-up internals. Try to get records of the transmission repairs if possible.

[Bigdav160]

They used a 27 spline input shaft until 1986, after that was a 30 spline input shaft.

I used to be a GM transmission tech. I've probably rebuilt 1000 or more 700R4's

I lot of time has passed but I do not think that is correct.

[68c10owner]

Originally Posted by Bigdav160

I used to be a GM transmission tech. I've probably rebuilt 1000 or more 700R4's

I lot of time has passed but I do not think that is correct.

Why do you not think its correct? Most people know they were 27 spline until they changed to 30 spline in 1987. Hell, my 85 700R4 was a 27 spline and when it was rebuilt it was changed to a 27 spline. For someone who claims to have built 1000 or more I would expect you to know a little more about the transmission.

[68c10owner]

You know, Ive been doing this for almost 30 years and I`ve always known the 700R4 to have a 27 spline input from 1981-1986 and 30 spline starting in 1987. Even my transmission friends who are GM techs of 30+years have told me this and the guy who built mine told me as well. I did a google search and saw several places that say 1984 was a mid year change to a 30 spline input. Looks as if I may have been wrong on the input spline count but there is still no reason to use a unit earlier than 1987 unless you already have it.

[63frankintruck]

Thanks guys for all the feedback. As it turns out the donor truck I went to check out would not stay running long enough to get a good test drive out of it.
I think I'm leaning toward going to Phoenix Trans or the like and just biting the bullet. (my 63 was supposed to be a budget build...........but then I think the only real way to do a budget build is after you have built the first vehicle)
(then you know all the little ins and outs for the next one)
Long story short, unless I just run across a great condition donor at a fair price, I will purchase new.
Thanks again for the advice and help!

[clinebarger]

The 30 spline input came out late in the '84 calendar year....Early '85 model year vehicles still got the 27 spline. So it was a running change during the '85 production run.