1984 Chevrolet k10 700r4 id help

[Matthew Smith]

Hey I have a 700r4 that came stock with the truck, but I'm not positive that it's the original. I will post a picture of the ID tag hopping someone more well versed with these transmissions can tell me more info about it. The truck is a 1984 Chevrolet k10 Silverado short box, from the RPO the transmission is correct, the motor is now a 350. From what I've gathered so far this truck uses the TV cable for shift points and line pressure, it has the break pedal switch to take it out of lock up, and uses the tip in switch for... I want to say telling the computer that it's okay to go into lock up I think, not 100% positive tho.

I'm reaching out to see if someone can help me with the ID tag, and want your opinions on whether or not I should keep the stock transmission converter lock up set up or should I go with B&M or some other aftermarket kits to fully control the 700r4's shift points and TC lock up. My shift points are way to early doesn't kick down when it should and just giving me overall poor performance with the current setup. Would love to hear something advice or solutions to better improve the driveability and overall performance. Thank you!

 

[HotRodPC]

Hard to make out that tag. Maybe my monitor, I don't know, but I can't make out most of it. If I had to guess, it may be an 86 transmission which means it's not the OE transmission. Just due to time, I'd guess that's it's not. 82-84 were the worst 700r4's and not even good cores. If you're looking for another core, try to find an 88 or later. 87 is doable too, but 88 and up have the most changes and updates and finally started getting a bit more relaible by that time.

 

[legopnuematic]

A 700r4 should have the original partial vin stamping on the passenger side rear above the pan rail.

If it has a tag adhered to it that would, to me suggest its been replaced/rebuilt at some point.

 

[Finkaire]

May just be a matter of adjustment

 

[Matthew Smith]

Unfortunately it looks like someone took a grinder to it

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[NickTransmissions]

Need to clarify some of your understanding of how these transmissions work based on your OP.

Governor controls the shift points; the TV cable's tension can make the shifts a little bit later or earlier but the governor is the locus of control for shift points. Purchase the Superior Tech governor weight and spring kit to make adjustments to the shift points.

Aftermarket TCC lock up kits, depending on how sophisticated they are, only control TCC lock up timing. The B&M kit gives you control over exactly when to lock up the TCC at whichever road speed you want once you're in forth gear.

 

[HotRodPC]

Unfortunately it looks like someone took a grinder to it

You must be registered for see images attach

It's very possilbe it was a factory reman unit. Most of those units failed they were so bad. So many got to go back to GM for warranty, some remanned with some fixes and then a sticker was put on them that's probably been washed or worn away by now. Those were so bad in 82-84, if the owner wanted it for the reliablity factor, GM was converting them back to Th350C transmissions which many times was just fine since many of those 1/2 ton trucks back then had 2.73 or 3.08 rear gears and didn't even need the OD. They may have even held up a bit better if GM would have ran 3.73's on the rear gears. The 700r4 was just junk. There was many changes made every year, after year and many parts were not backwards compatible, or if they were, you had to change other parts to support the changed part. By 87 and 88, they started getting better. The 88 and up also among many of the updates, has a tiny secondary valve body and why the 88 and up cores are the better ones to find and use for rebuilds.

 

[HotRodPC]

BTW, there was so many changes and updates to the 700r4, that ATSG makes a manual just for the updates and changes. It's a good book to have on hand if you're a builder. The book takes every year, by year and talks about what changes were made that year, and if it was a half year or not. So like a change may have been made to late or 86 and half year model units. The book also talks about which updates are backwards compatible and what other parts must be used if you do the update, and how to identify if it's an updated part or not. It could be something as simple as a clutch drum pressure plate that's an update, and you need to know how to ID the updated plate from the OE plate they want you to throw away and not use. This comes in handy if you're building one and then you know if it's been previously rebuilt and if the update was made when it was rebuilt.

I just simply won't even waste my time with an 82-86 700r4. And something else to note, 82-84 had a smaller spline input. So you have to be careful and get the correct torque conveter if using the smaller spline input shaft. Most of those have probably been updated to the bigger input shaft by now I'd think, but never know. Some people aren't aware of these things, so they don't know to update them.

 

[NickTransmissions]

The particular year isn't as important as vintage (version) of 700R4 that you may have. There are five different vintages of 700r4 - they and their differentiating characteristics are as follows:

> 1982-E1984: Non-aux valve body; 27 spline input shaft w/narrow bore pump stator; VB provisioned for TCC mechanical control
> L1984-1986: Non-aux valve body; 30-spline input shaft with wide bore pump stator; VB provisioned for TCC mechanical control
> 1987: Aux valve body, 30-spline input shaft, wide bore stator, updated input drum; VB provisioned for TCC mechanical control
> 1988-1992: Aux valve body, 30-spline input shaft, wide bore stator, updated input drum; VB no longer provisioned for TCC mechanical control
> 1993 (pass cars only): Aux valve body, 30-spline input shaft, wide bore stator, 3rd check ball in VB for reverse input


If your transmission is original to the vehicle, you may have either the first or second vintage. The second vintage is a stronger transmission owing to the design improvements to the input shaft and pump stator. The strongest, most reliable overall are the final two.

 

[Broken85]

I have the same truck and powertrain. Yours probably came stock with a 305 as well. OD transmission, lock up TC, 5.0liter motor and who can forget the rock-crushing 307 axle. They were built for fuel economy, and at that in my opinion, they failed. Around 55mph around town, they constantly go in and out of lock up. 700R4 is a good transmission. They even used them in the K and C20’s. If you are looking at what to invest in, I would try to change axle gear ratio first (if the transmission is working well). 342 or 373 (maybe the later) will make you a lot happier and likely improve mileage around town.

For shift points, do a pressure test on the transmission and try to better dial in the TV cable. It is the most cost effective first step. Pressure test kits are $25 on Amazon. You might tighten it up a few clicks and be much happier with it.

Good looking short bed!