How to Identify a 700r4

[HotRodPC]

That's a 700r4.

I am sort of slapping myself with my purchase every time I find out something that the seller told me that is wrong....

I thought I had a TH350... hell 3 gears only worked and then I somehow "broke it" and only had 2 gears. Tranny wants to drop out of gear and coast when I hit 40mph+... unless I have it in a lower gear and it locks up.

So I think it's a 700r4, which is bitter sweet because I like the fact it's 4 spd as I don't plan on hot rodding it too much. I prefer the everyday drive ability.

So I bought a Modulator valve and governor gear... aaaand it's not even a TH350!!

I finally crawled under there tonight and wondered for a few minutes why there was no vacuum modulator!!!

Can anyone confirm??

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Have you got a pic of the pan? It's appears to be missing a letter to be a 700r4. They do get stamped wrong at times though. 1FY? If it's a 700r4, it's likely from a Camaro or Firebird originally as in F Body car and the 1 would suggest a 1991 unit which is much more desirable over the 86 and earlier units.

 

[krautmeister]

That's a 700r4.

Have you got a pic of the pan? It's appears to be missing a letter to be a 700r4. They do get stamped wrong at times though. 1FY? If it's a 700r4, it's likely from a Camaro or Firebird originally as in F Body car and the 1 would suggest a 1991 unit which is much more desirable over the 86 and earlier units.

I'll get a picture later but it's rectangular and doesn't have the chamfered corners.

I'll have to post up in the general thread on diagnosis of the shift issues. Only uses 2 gears.

 

[HotRodPC]

I'll get a picture later but it's rectangular and doesn't have the chamfered corners.

I'll have to post up in the general thread on diagnosis of the shift issues. Only uses 2 gears.

Yeah it's a 700r4. Sounds like you lost the 3/4 clutch pack. So you've got 1st and 2nd and that's it.

 

[HotRodPC]

On 2nd thought, you said it had 3 gears for awhile, now just 2? You might have a broken sunshell and lost 2 and 4th. You'd know for sure if you lose reverse.

 

[krautmeister]

On 2nd thought, you said it had 3 gears for awhile, now just 2? You might have a broken sunshell and lost 2 and 4th. You'd know for sure if you lose reverse.

I have Reverse fine. I'm totally new to this whole animal of GM trans/engines... but the TV cable is a mess as I've been going through research. It was pretty butchered and I found it disconnected with a rigged connector after I "lost" 3rd. The truck lurches pretty hard when engaged into D, L1, L2.... maybe the line pressure is high? Need a new TV cable just because I have no idea how this rig has been worked on...seems a lot of corners have been cut.

 

[74 Shortbed]

That cable has to be dead nuts or nothing works right, be a good idea to hook up a pressure gauge to monitor the pressure through the range.

 

[HotRodPC]

I have Reverse fine. I'm totally new to this whole animal of GM trans/engines... but the TV cable is a mess as I've been going through research. It was pretty butchered and I found it disconnected with a rigged connector after I "lost" 3rd. The truck lurches pretty hard when engaged into D, L1, L2.... maybe the line pressure is high? Need a new TV cable just because I have no idea how this rig has been worked on...seems a lot of corners have been cut.

That right there answers the question for me. Your 3/4 clutch pack is toasted so you only have 1st and 2nd. One thing about a 700r4, That TV cable not only sets shift points and passing gear, it also regulates fluid pressure via the Throttle Valve, hence TV cable. If that cable was disconnected or not right, then TV valve never raised the fluid pressure to hold the clutches tighter for more throttle and they slipped until they burnt up. Light throttle means less pressure, More throttle means higher pressure. TV cable has to be adjusted right or the transmission dies a quick death. Unlike a Tubo 350, where if the cable isn't hooked up or adjust right, you just get crappy shift points and no passing gear if not hooked up but it won't kill the transmission in a short period of time like a 700r4. If while the cable is not hooked up on a 700r4, and if you're driving it hard, you can toast them clutches in less than 100 miles. Hooked up but a loose adjustment you can cook it in less than 500 miles.

 

[86suburbanNJ609]

My transmission has the code 3TK1LON

I cannot get any information on these numbers just wondering if this is the original to the truck or not.

 

[NejiDannii]

I’m new on here and we’ll my transmission went out won’t go on reverse when on gear just a rattling noise so I’m guessing I need a new transmission and I don’t know what type of transmission I have it’s a 84 C10 Silverado with a 350 Engine and it’s automatic. Please help

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[4WDKC]

hard to tell from the pic but looks to be a 700r4, get a pic of the pan

 

[HotRodPC]

I’m new on here and we’ll my transmission went out won’t go on reverse when on gear just a rattling noise so I’m guessing I need a new transmission and I don’t know what type of transmission I have it’s a 84 C10 Silverado with a 350 Engine and it’s automatic. Please help

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A pan pic would be best, but that's looking like a 700r4 from what I can see. I won't swear to it until I seen a pan pic.

 

[HotRodPC]

4WDKC beat me by a second or 2.

 

[NejiDannii]

Hopefully this will help

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[4WDKC]

looks to be a 700r4

 

[82Diesel]

Are the 700r4s built for the 6.2 diesels any different than the ones used for Gas?
That was one thing I am curious about... Mine is the 1982 Chevrolet k10 first year for 6.2 diesel and 700r4.

trying to find out production year.