rjshull

Hey guys,
I have an 88 formula 350 with the 700r4 in it. The tranny was fine up till a few days ago, after driving the car for about an hour the tranny was just fine I pulled up to a stop sign and stopped when I went to take back off the tranny would no longer shift into 3rd so I limped home. When I got home I jacked the car up to check the vacuum line going to the modulator valve and found out that this tranny does not have one. What do I need to do to fix this tranny?

Also, when I jacked the car up I noticed that I have a massive tranny leak. The front edges of the pan are wet, does not seem to be the front seal as it is dry behind the converter. Also I noticed that when the PO changed the tranny he cut off the mounting bracket for the dip stick tube and the front of the tube is about 3/16" about the top lip of the hole. Would this cause a massive leak?

Any help is appreciated.
Thanks

SLEEPER 86

low fluid will definitely make a no-go situation.
are you saying he cut the whole dipstick tube off? or is it not connected to the tranny?
either way there is potential for leakage. was the motor from a scrap yard? they often torch anything in their way.
if it was me, i'd start looking that car over VERY carefully.
Eric B

rjshull

While I do have a fluid leak it is not the culprit, or at least I dont think as i have put more than enough fluid into to make it work and still nothing. The dipstick tube is there just not the support bracket which is allowing the tube to be loss and not seated in completely. The motor is stock (not for long) and has caused me no problems in the past. In a 700r4 what controls the shift points like a modulator valve does in other trannys? I think my problem is that but i may be wrong.

Also, where can I get the gasket/oring for the dipstick tube

Rolling Thunder

Well on a 700r4 there is no vacuum modulator. On the 700r4 they have a TV cable. It accomplishes the same thing though just using different means. If you have a massive leak i would definitely chase that down. It may have been overheated or damaged from run low on fluid. However again start with the leak and well go from there.

KNBlazer

your governor controls your shifts...

rjshull

ok one more question for you guys. Is there a build code on the tranny and if so where is it? Tomorrow i am going to drop the pan and check it out, hopefully I will see a clear pan but I don't think i will be that lucky and if the pan is full of metal shavings i will need to know the year in order to get a rebuild kit.

Governer, just another reason to go old school and rip out everything.

If I do need to rebuild it, what kit should I get? I am only looking for this tranny to last at most a nother year as once I get the engine done I am going to drop in a th400.

KNBlazer

well if you have metal shavings.. it won't be as easy as just ordering a kit... you will have to visually and carefully inspect each hard part and then go from there...

http://www.shinseiauto.com/japanese/...gmth700r44.pdf

Rolling Thunder

Well just incase your confused its not a govenor in the typical sence that it limits speed. The way it works is the shift is controlled by the govener is like a small pump. It pressure is built up against the TV valve in something like a game of tug of war to determine when the shifts will happen. The governor is kind of like a speed sensor and the TV cable helps determine the load (the more load the later the shifts). Even a th400 would have something similar but with a vacuum modulator instead of a TV cable. As for the rest of your question it wouldnt be worth it to rebuild it to last a month it would be cheaper to just buy a 700r4 off craigslist or from a junkyard if all you need is it to last for a month or you could just wait. There is a date code on the passenger side of the trans just above the transmission pan in the rear corner but again not worth rebuilding if only for a month even if it was just in need of a basic overhaul.

KNBlazer

he wants it to last a year, not a month... I say overhaul, but then again it's just me...

rjshull

Like KNBlazer said, i need it to last for another year. I dropped the pan and it is clean, no metal shavings. What do i need to do to fix this tranny?

Rolling Thunder

Yea my bad i dont know why i kept saying month lol. Its still not worth it though. Its probably going to cost atleast $200 to get a decent quality stock rebuild kit. This is assuming no "hard parts" are bad which there is a good chance there may be adding to the cost. This is just the price of the basic you will need parts. This does not include the tools that will be needed or the documentation you will need to take this on which will be pretty pricey it will likely add atleast another $150 if you can find good deals on ebay on used tools and such. Then theres time to learn how to do this as this isnt exactly the kinda project you just jump into your really have to have a good idea as to what needs to be done how it should be done. The 700r4 is one of the more complicated transmissions that even transmissions shops screw up if not experienced. Its not like the th350s which although not simple are definitely a less sensitive trans. It would be one thing if you meant to keep it but you can get a trans with a guarantee from the junk yard for less than the price of the parts to rebuild your trans. Or you can be a little risky and get one for even less on craigslist. I usually am the first to say have at it anything can be done but in this case i just dont think its worth the money or the time for a temp fix.

KNBlazer

no it's not an easy task... my mechanic that does the things I'm too lazy to do will work on a 350, but will refuse to work on a 700r4... or any other transmission for that matter...

KNBlazer

I think you should take it to a transmission shop or have someone that knows these transmissions, if the fluid looked clean, chances are you don't need an overhaul, perhaps you just need to replace a small 5 dollar part...

TZFBird

I had my TV cable adjusted wrong and burned up the 3-4 clutch pack on my first run of the rebuilt transmission. If you are comfortable pulling the trans and investigating I'm pretty sure you'll find that just those clutches are burned up. I've done a few "cheap'o" rebuilds for people who can't afford getting a properly rebuilt transmission and I've just replaced a burned clutch pack(due to fluid level getting low and starving pump of oil).

Here's a link to the 700R4 3-4 clutch frictions. They have a $13 minimum shipping charge, but it's better than a $50 kit for a few parts.
https://www.wittrans.com/SchematicPa...4&LinkCode=100

When I burned up my clutches I limped about 10 miles at 25mph on the highway to get back home. The fluid was still clean and red. The clutches must have just glazed quickly because they didn't release any material into the fluid.

This is just a suggestion if you are needing to get by for a while until everything gets done properly. But I'd consider all other possibilities of what caused this before you even that work only to have it fail again.

86GMC

hey guys,

i have a question bout the 700R4 tranny. my truck wont shift out of first gear by its self, when i reach about 15 mph i have to let off the gas pedal then re-push it for it to shift into second gear. now i have read some of the posts on here about there not being a vacuum module on the 700r4's. so any ideas on what could be causing my tranny to make me do this. the tranny has full fluid. been wanting to change tranny but don't have the money to yet. if anyone knows plz let me know how to fix this situation

1992Vortec

Check the TV cable to make sure it is properly "SET" you can find a bunch of info on who to set it... Push the big button and slide the plastic adjuster all the way in "towards the fire all" then rotate your throttle body to WOT you're done. That is if you have a OEM style TV cable.

86GMC

ok, so i found the TV cable, but dont see a way to "adjust" it. can any one help me out? new to doing tranny work so any suggestions will help greatly. thank you

Scorpner

iTrader: (4)

There's a "D" shaped button you push in to reset it. While it's depressed, you can move the cable in to take out slack for the next step. Then release the button.
Then either move the throttle lever all the way out, or some people push the pedal all the way down from inside of the car to make the adjustment. It should click as it's doing so, but most importantly, the cable should be tight at the full extension of the throttle. I sometimes disconnect the TV cable at the throttle lever and compare it's position with the throttle lever retainer at full extension. If it isn't adjusted correctly it can ruin your transmission.

A couple of vids to show it.


@ 1:37> http://www.youtube.com/watch?feature...VrTVwcVn4#t=97

@ 2:00> http://www.youtube.com/watch?feature...n4OzneCM#t=122

More info:
https://www.thirdgen.org/forums/tran...djustment.html

http://www.tvmadeez.com/article/index.php