700r4 Old vs New

[soltvedt]

I have heard that there is difference between the 1983-87 700r4 and the 88-92 700r4 transmissions.

Right now I have a 1991 Chevy half ton 2wd truck with a 305 engine. The stock 700r4 transmission is in it, but gears 3 and 4 are gone, and I'd like to install whatever replacement 2wd 700r4 I find first.

So I was wondering, if I can find an "old" 700r4 to put in it, is there any modifications I will need to make to go back to the "old" version of the tranny? (Wire plug style, speedo hookup, tv cable length & bracket, housing style & gasket, drive shaft length, etc.)?

Or will everything be TOTALLY interchangable, and be able to be bolted right on?

I understand that the stock "new" style is more reliable than the stock "old" style, but I'm not concerned about that. I just want to know (for instance) if I find a good 1985 2wd Suburban tranny, if it will go right into my 1991 2wd half ton truck without any mods at all.

[Crosley.In.AZ]

I have heard that there is difference between the 1983-87 700r4 and the 88-92 700r4 transmissions.

Right now I have a 1991 Chevy half ton 2wd truck with a 305 engine. The stock 700r4 transmission is in it, but gears 3 and 4 are gone, and I'd like to install whatever replacement 2wd 700r4 I find first.

So I was wondering, if I can find an "old" 700r4 to put in it, is there any modifications I will need to make to go back to the "old" version of the tranny? (Wire plug style, speedo hookup, tv cable length & bracket, housing style & gasket, drive shaft length, etc.)?

Or will everything be TOTALLY interchangable, and be able to be bolted right on?

I understand that the stock "new" style is more reliable than the stock "old" style, but I'm not concerned about that. I just want to know (for instance) if I find a good 1985 2wd Suburban tranny, if it will go right into my 1991 2wd half ton truck without any mods at all.

The major changes were introduced in mid 1987.

You will need to swap your internal wire harness with lockup solenoid from the 91 truck to the earlier tranny IF that is what you find.

You will need to swap the reluctor ring pressed onto the output shaft  for the 1991  electronic speed-O from your trans to the earlier unit.

I'd be careful on how early a trans you find..... early units(82-84) had a 27 spline input shaft. You can NOT inter change the converters from 27 spline to 30 spline input shafts.

Early trannys from diesel powered vehicles will shift too early for a gas powered engine. The diesel torque converter is too low stall RPM for the gas engine

[soltvedt]

Thanks Tony!

I'll look out for those things once I take a look and see what year tranny I picked up last night. I found out how to identify the tranny here:

http://p210.ezboard.com/f7387chevytrucks88686frm2.showMessage?topicID=1067.topic

I'll look at my numbers and count the splines, and if I find out that it's a really old one (83-84), then I may have more questions, but until then, thanks a ton for the feedback!

[soltvedt]

Well, it turns out I got an "early" unit. The 700r4 I got is stamped as an 1984 model, and the torque converter from my 1991 was NOT interchangable...just as Tony warned me about. (The the transmission's shaft has 27 splines instead of 30.)

So, I had a friend stop in at the local "Advanced Auto Parts" store, and according to the guy there, they don't believe that simply ordering a 1984 torque converter (with 27 splines) will work because they said that it will not bolt up to the 1991 the flex plate. And on top of that, they also said that swapping out the flex plate will not help either because the "button" on the torque converter will not fit into the crank on the engine.

Does this all sound correct? Or is there a custom torque converter out there that someone builds that will fit? Or do I have any other options (other than changing the shaft in the transmission)?

[rooster]

Well, it turns out I got an "early" unit. The 700r4 I got is stamped as an 1984 model, and the torque converter from my 1991 was NOT interchangable...just as Tony warned me about. (The the transmission's shaft has 27 splines instead of 30.)

So, I had a friend stop in at the local "Advanced Auto Parts" store, and according to the guy there, they don't believe that simply ordering a 1984 torque converter (with 27 splines) will work because they said that it will not bolt up to the 1991 the flex plate. And on top of that, they also said that swapping out the flex plate will not help either because the "button" on the torque converter will not fit into the crank on the engine.

Does this all sound correct? Or is there a custom torque converter out there that someone builds that will fit? Or do I have any other options (other than changing the shaft in the transmission)?

Sounds like Murphs Law Has rested upon you! Keep looking, you will win.
Good luck
Denny

[Crosley.In.AZ]

Well, it turns out I got an "early" unit. The 700r4 I got is stamped as an 1984 model, and the torque converter from my 1991 was NOT interchangable...just as Tony warned me about. (The the transmission's shaft has 27 splines instead of 30.)

So, I had a friend stop in at the local "Advanced Auto Parts" store, and according to the guy there, they don't believe that simply ordering a 1984 torque converter (with 27 splines) will work because they said that it will not bolt up to the 1991 the flex plate. And on top of that, they also said that swapping out the flex plate will not help either because the "button" on the torque converter will not fit into the crank on the engine.

Does this all sound correct? Or is there a custom torque converter out there that someone builds that will fit? Or do I have any other options (other than changing the shaft in the transmission)?

the parts guy is full of crap.  Converter has the same bolt pattern 1984 to 1991.... and later too.

The crank hub on the front of the converter is the same too.

Where do they get these idiots at?

[tom36]

the parts guy is full of crap.  Converter has the same bolt pattern 1984 to 1991.... and later too.

The crank hub on the front of the converter is the same too.

Where do they get these idiots at?

Don't hold back Tony      
 Tom...

[Crosley.In.AZ]

the parts guy is full of crap.  Converter has the same bolt pattern 1984 to 1991.... and later too.

The crank hub on the front of the converter is the same too.

Where do they get these idiots at?

Don't hold back Tony      
 Tom...

I probably should not blame the parts people..... they simply read a computer screen  for information.


:)S(

[soltvedt]

Thanks Tony.

I kinda thought that it sounded fishy. I never talked to the parts guy myself, but I was totally baffled when I heard the false news that it would not fit.

So, based on this forum's feedback, I ordered up a converter for an "early" 1984 700r4 transmission (27 spline), and I'm gonna give it a shot.

Tony, your advice has been right on the money up to this point, so I have high hopes.

Nice having you guys around! I'll keep y'all updated on the progress.

[homer]

I bet he forgot to ask you what color the seats were.

Homer

[Crosley.In.AZ]

Thanks Tony.

I kinda thought that it sounded fishy. I never talked to the parts guy myself, but I was totally baffled when I heard the false news that it would not fit.

So, based on this forum's feedback, I ordered up a converter for an "early" 1984 700r4 transmission (27 spline), and I'm gonna give it a shot.

Tony, your advice has been right on the money up to this point, so I have high hopes.

Nice having you guys around! I'll keep y'all updated on the progress.

it's almost like I have done this tranny thing for a decade or 3 .

:ha)

[tomslik]

Thanks Tony.

I kinda thought that it sounded fishy. I never talked to the parts guy myself, but I was totally baffled when I heard the false news that it would not fit.

So, based on this forum's feedback, I ordered up a converter for an "early" 1984 700r4 transmission (27 spline), and I'm gonna give it a shot.

Tony, your advice has been right on the money up to this point, so I have high hopes.

Nice having you guys around! I'll keep y'all updated on the progress.

it's almost like I have done this tranny thing for a decade or 3 .

:ha)

same tranny?
you'd think you could get it right one of these days

[soltvedt]

UPDATE:

Great news!

The 27 spline torque converter fit perfectly onto the transmission, and onto the flexplate, and into the crank.

I swapped the transmission tailsections to make the speedometer swap easier. I ended up having to melt the brazing that was holding the metal speedometer gear onto the output shaft, and re-braze it onto the other transmission since they were different styles. (One was plastic, one was metal.)

All things considered, the swap went perfectly. Everything was completely interchangeable.

And guess what
THE $50.00 1984 TRANSMISSION WORKED WITH NO REBUILD!!!
This absoluely blew my mind. I thought for sure I'd be pulling it out and rebuilding it.

Not only did I get my 3rd and 4th gears back, but it will actually drive in 4th gear at 40-45 mph. Never had that happen in 4,000 miles of driving with the old tranny. Before, I could only occasionally get it into 4th gear, and I had to really get it up to speed before it would go. That is, if it would go.

Now, onto the supposedly highly important "TV cable" adjustment. I have questions.

I left the same cable that was on the 91 truck on there, I didn't swap it out. After hooking it up to the 84 transmission, I then hooked it up top. I decided to just leave the slider right where it was...without "pressing the release button" on the adjuster. When at full throttle position, I checked the exposed metal cable by pressing on it, and there wasn't any obvious extra cable slack to be pulled. This is how I've ran the transmission so far, and when on the road during the initial tests, the shifting and downshifting "feels right".

So, my question is, if everything is shifting and downshifting at what "feels to be" the right places, is everything ok? Or what mandatory things should I check for so I don't ruin the transmission? Does anyone recommend "pressing that adjuster button" and setting it (by opening the throttle all the way) to "set" it properly? Or is that not necessary if it's currently running right?

Another rumor I've heard is that it is better to have the TV cable to tight than too loose to be "safe". What exactly will an adjuster setting of too tight "feel like" when driving the truck during downshifts? (Or what will too loose "feel like"?)

Am I just paranoid about the TV cable?

[1FATGMC]

UPDATE:

Great news!

The 27 spline torque converter fit perfectly onto the transmission, and onto the flexplate, and into the crank.

I swapped the transmission tailsections to make the speedometer swap easier. I ended up having to melt the brazing that was holding the metal speedometer gear onto the output shaft, and re-braze it onto the other transmission since they were different styles. (One was plastic, one was metal.)

All things considered, the swap went perfectly. Everything was completely interchangeable.

And guess what
THE $50.00 1984 TRANSMISSION WORKED WITH NO REBUILD!!!
This absoluely blew my mind. I thought for sure I'd be pulling it out and rebuilding it.

Not only did I get my 3rd and 4th gears back, but it will actually drive in 4th gear at 40-45 mph. Never had that happen in 4,000 miles of driving with the old tranny. Before, I could only occasionally get it into 4th gear, and I had to really get it up to speed before it would go. That is, if it would go.

That is great :!:  :!: .   I got a free 200R4 from Hooley a couple years ago and John (WZJUNK) helped me put it in when I was in their area and my transmission went south in the old Buick we have.  I worried about it as Hooley got it from someone else and we had no history on it.  Since then it has been back to Mich. and to Calif.  with no problems.

Am I just paranoid about the TV cable?

You can adjust it/check it with pressure or set it like I've done on this link.  I'm too tired to type it all in so just go to the first page on the link below and read it.  I can't remember how you have it hooked to the carb (running a carb??), but the geometry there is as important as the adjustment.

700R4 Info HERE  

c ya,

Sum

[Crosley.In.AZ]

  I can't remember how you have it hooked to the carb (running a carb??), but the geometry there is as important as the adjustment.

700R4 Info HERE  

c ya,

Sum

a 1991 truck should be EFI