700r4 tranny experts
Thread Starter
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
700r4 tranny experts
I have an '88 700r4 tranny in my '72 vette, hotrod....
just now, I think I blew something critical...there is NO third gear, just freewheels, forward or backdown, engine freerevs...1st and 2nd with lockup are normal.....goes into gear fine....move lever to 2nd to keep car going uphills...
any ideas??? tranny fluid is full of bubbles on dipstick, runs at 178F in temp...and appears normal, not scorched or burnt/anything....tranny was redone allmost 5 years ago and in car fine since then...this happened just today all at once on a blast down the road....engine revved way up...I lifted....
please, this is an emergency poopieuation....
GENE :D :D :rolleyes: :mad :confused: :eek:
Burning Brakes
Joined: Mar 2001
Posts: 1,211
Likes: 5
From: Nashville TN
Re: 700r4 tranny experts (mrvette)
Sounds to me like you blew up the third gear clutch pack. A notoriously weak element in that transmission. You probably lost just enough clutch material to prevent third gear from grabbing. When you loose third gear you automatically loose 4th. Lock up and reverse still funtion normally as do first and second. Hate to be the bearer of bad news but you are looking at a transmission. My fluid did not look that bad, nor did I smell anything burning.
If yout TV geometry is not correct this will be one of the first things to go. One of the common modifications to this trans is to use a 9 disc clutch pack as opposed to the factory 6 disc setup. What are you using for a carb ?
If yout TV geometry is not correct this will be one of the first things to go. One of the common modifications to this trans is to use a 9 disc clutch pack as opposed to the factory 6 disc setup. What are you using for a carb ?
Thread Starter
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Re: 700r4 tranny experts (Ingar, Norway)
Well I let it cool down a bit, will try it im the morning. but I suspect you all are correct,....I fiddled with the TV cable, will drive in AM and see...
last time the TV unstuck itself over nite, when cold....
it's a listed failure in the GM '87 vette repair manual....
so if it's a 3/4 clutch pack, what does one typically cost and I mean 9 dick heavy duty....and what other parts am I likely to need, hope it's not a whole rebuild kit....I need find in the manual here where that pack is located...I heard it's in a drum of some sort....
also supposed to be a one way sprag set in there, and it's famous also...
Anybody know what it takes in way of tools to get to this clutch pak???
I have a set of internal/external snap ring pliars...anything else special???
GENE
last time the TV unstuck itself over nite, when cold....
it's a listed failure in the GM '87 vette repair manual....
so if it's a 3/4 clutch pack, what does one typically cost and I mean 9 dick heavy duty....and what other parts am I likely to need, hope it's not a whole rebuild kit....I need find in the manual here where that pack is located...I heard it's in a drum of some sort....
also supposed to be a one way sprag set in there, and it's famous also...
Anybody know what it takes in way of tools to get to this clutch pak???
I have a set of internal/external snap ring pliars...anything else special???
GENE
Burning Brakes
Joined: Mar 2001
Posts: 1,211
Likes: 5
From: Nashville TN
Re: 700r4 tranny experts (mrvette)
When my 700r4 went I thought about just trying to do a third gear clutch pack. Once I got into the tranny I saw a few other things that just didn't look good. I took it to a tranny guy and he found a bunch of stuff that was not in good shape. There is also a lot of debris probably floating around in that unit. It should be taken down and cleaned out. You might want to give thought to redoing the whole tranny as long as you are going in there.
Melting Slicks
Joined: Oct 1999
Posts: 2,581
Likes: 14
From: Tolar Texas
Re: 700r4 tranny experts (mrvette)
Here's another vote for "3-4" clutch-pack failure. Could be something else (stuck valve) but the symptoms sound like what I experienced with my 700R4. Low line pressure is what caused my transmission to fail.
I'm told that there is more than one way to prevent this particular weakness.
Good luck on the rebuild. Hopefully it will turn out better than ever before.
I'm told that there is more than one way to prevent this particular weakness.
Good luck on the rebuild. Hopefully it will turn out better than ever before.
Racer
Joined: Apr 2000
Posts: 499
Likes: 0
From: Kristiansand
Re: 700r4 tranny experts (mrvette)
Gene:
You should get the Haynes manual. This has pictures of every step in a rebuild. As far as I can tell the only special tool needed is a spring compressor (which you can make yourself). And bushing tools if you are going to replace bushings (also possible to make).
The ATSG manuals are also good as a reference, but don't have all the pictures.
The experts at thirdgen.org recommend to install these parts:
TransGo shift and pump kit (the shiftkit solves the stuck TV problem among others), 4L60E 3-4 pack and input sprag assy, (they seems to prefer Borg Warner clutches), teflon front bushing, Corvette rear planetary gear and new GM Sun Shell, Corvette 2-4band servo, .500 TV boost valve, .296 PR boost valve. Minimum endplay settings.
Aux cooler (bypass radiator).
You should look at the different options at the probuilt website http://www.pro-built.net
http://www.transonline.com is the best source I've found for rebuild information.
And there is a lot of info in the thirdgen.org archives.
[Modified by Ingar, Norway, 11:44 AM 4/28/2002]
You should get the Haynes manual. This has pictures of every step in a rebuild. As far as I can tell the only special tool needed is a spring compressor (which you can make yourself). And bushing tools if you are going to replace bushings (also possible to make).
The ATSG manuals are also good as a reference, but don't have all the pictures.
The experts at thirdgen.org recommend to install these parts:
TransGo shift and pump kit (the shiftkit solves the stuck TV problem among others), 4L60E 3-4 pack and input sprag assy, (they seems to prefer Borg Warner clutches), teflon front bushing, Corvette rear planetary gear and new GM Sun Shell, Corvette 2-4band servo, .500 TV boost valve, .296 PR boost valve. Minimum endplay settings.
Aux cooler (bypass radiator).
You should look at the different options at the probuilt website http://www.pro-built.net
http://www.transonline.com is the best source I've found for rebuild information.
And there is a lot of info in the thirdgen.org archives.
[Modified by Ingar, Norway, 11:44 AM 4/28/2002]
Burning Brakes
Joined: Mar 2001
Posts: 1,211
Likes: 5
From: Nashville TN
Re: 700r4 tranny experts (Ingar, Norway)
When talking transmission cooling. You should never bypass the fluid cooling. It is the most efficent means of removing heat from the transmission fluid. The best practice is to install a air-fluid cooler after the fluid exits the radiator. This will allow maximun cooling.
Depending on what carb you are using you might want to consider one of these:
http://www.powerglide.com/parts/parts/AS2-02K.htm
http://www.powerglide.com/parts/parts/AS3-03K.htm
I put one on my edelbrock carb and it made a world of difference.
Depending on what carb you are using you might want to consider one of these:
http://www.powerglide.com/parts/parts/AS2-02K.htm
http://www.powerglide.com/parts/parts/AS3-03K.htm
I put one on my edelbrock carb and it made a world of difference.
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Racer
Joined: Apr 2000
Posts: 499
Likes: 0
From: Kristiansand
Re: 700r4 tranny experts (mrvette)
Derek:
Do you know the total TV cable pull-length with the Edelbrock adapter?
Regarding cooling, yes, I know people have strong and different opinions on this.
If you have a well designed cooling system with sufficient overhead, using the radiator should be ok.
But if you, as many on this forum have been reporting, have a system that operates on its limits, bypassing the radiator might be better.
Heat convection is much better to water than air, but it doesn't help if the water is too hot. (near 150oF which is the max recommended trans temp.)
Also, your clutches are history if you have a leak and get antifreeze in the transmission.
I'm only using the radiator cooler and the trans haven't been above 70oF, even on long trips. But I live in a tempered climate.
Do you know the total TV cable pull-length with the Edelbrock adapter?
Regarding cooling, yes, I know people have strong and different opinions on this.
If you have a well designed cooling system with sufficient overhead, using the radiator should be ok.
But if you, as many on this forum have been reporting, have a system that operates on its limits, bypassing the radiator might be better.
Heat convection is much better to water than air, but it doesn't help if the water is too hot. (near 150oF which is the max recommended trans temp.)
Also, your clutches are history if you have a leak and get antifreeze in the transmission.
I'm only using the radiator cooler and the trans haven't been above 70oF, even on long trips. But I live in a tempered climate.
