700R4 Slipping Bad!!!
Thread Starter
Heel & Toe
Joined: Jan 2012
Posts: 19
Likes: 0
700R4 Slipping Bad!!!
Hey Guys I've got a 1988 Corvette with 70,000 miles and the L98 and the 700R4 transmission in it. When I bought it about 7 months ago it had been sitting for a year and a half in this lady's garage after the death of her husband. I drove it and only had minor problems pop up for several months until about 3 weeks ago when the transmission started slipping so bad it barely pulls itself even if you run the RPM up. I had just left the parts store and it pulled great and I went about a 1/4 mile, stopped at a traffic light and when I tried to start off it was like it was in neutral. It was my daily driver before this and had been working great. I didn't baby it but I also wasn't trying to spin the tires every time I took off. (They cost too much!! lol) I changed the fluid and filter but that didn't change it any. There wasn't any metal shavings or debris in the fluid and the magnet in the pan only had a little grey sludge built up on it. I'm wondering if the front pump or the torque converter might be the problem and if anyone can tell me how to determine if either one is? If I rev it to 2800 - 3000 RPM it will pull a little but no enough to drive. Any ideas or suggestions?
Thanks,
Chris
Thanks,
Chris
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
Check the TV cable, Mine slipped and I had to keep adjusting it till I got a new one.
Look at the side of the throttle cable. One of them looks kinda like a backwards D with a blackish or whitish center.
Look closely at the black plastic jacket around the cable. You will see a wear mark on the tubular black plastic jacket if the adjuster slipped.
To adjust it, push in the white (or blackish) center, and slide the black jacket (on the cable) towards the back of the car, so it goes inside the cable housing, and with the engine off, push the whitish center and pull the throttle to full throttle.
The center black jacket will come out of the adjuster to the wear mark.
That should be adjusted.
Now when you adjust the cable, you adjust the pressure in the trans.
If it still drives the same, pull the adjuster farther, and see if it changes. If it changes slightly, you may have an internal problem in the valve body with a leak or worn valve body plate, but the pump is mechanical, and I would think that it would give about 100 miles of trouble before it gave up.
Look at the side of the throttle cable. One of them looks kinda like a backwards D with a blackish or whitish center.
Look closely at the black plastic jacket around the cable. You will see a wear mark on the tubular black plastic jacket if the adjuster slipped.
To adjust it, push in the white (or blackish) center, and slide the black jacket (on the cable) towards the back of the car, so it goes inside the cable housing, and with the engine off, push the whitish center and pull the throttle to full throttle.
The center black jacket will come out of the adjuster to the wear mark.
That should be adjusted.
Now when you adjust the cable, you adjust the pressure in the trans.
If it still drives the same, pull the adjuster farther, and see if it changes. If it changes slightly, you may have an internal problem in the valve body with a leak or worn valve body plate, but the pump is mechanical, and I would think that it would give about 100 miles of trouble before it gave up.
Last edited by coupeguy2001; Aug 7, 2012 at 03:16 PM.
Thread Starter
Heel & Toe
Joined: Jan 2012
Posts: 19
Likes: 0
I checked the TV cable and it's good. Since the transmission was pulling and shifting good prior to this and it suddenly stopped pulling I'm thinking the torque convertor and/or the front pump failed. I'm open to anymore suggestions or ideas.
Team Owner
Joined: Sep 2003
Posts: 20,179
Likes: 673
From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
Check the fluid for color and smell.
Color - clear red=OK dark red=NOt OK
Smell - funky oil smell=OK burnt like an old clutch= NOT OK
IMO find a reputable trans shop and have them install an overhauled unit with a warranty.
Or buy one and install it yourself.
Color - clear red=OK dark red=NOt OK
Smell - funky oil smell=OK burnt like an old clutch= NOT OK
IMO find a reputable trans shop and have them install an overhauled unit with a warranty.
Or buy one and install it yourself.
Last edited by JrRifleCoach; Aug 8, 2012 at 12:06 PM.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
Have a transmission shop connect a pressure gauge and check the pressures. That will tell you a lot about what's going on.
You need good line pressure to keep the frictions clamped tightly. If the line pressure is low the frictions will slip and eventually burn.
You need good line pressure to keep the frictions clamped tightly. If the line pressure is low the frictions will slip and eventually burn.
Thread Starter
Heel & Toe
Joined: Jan 2012
Posts: 19
Likes: 0
Bowtie Overdrives has a site that shows you where the port is on the left side of the transmission for pressure checks and how to do it. Thanks for reminding me. I'm a big DIY guy and hate to pay someone else to do something I can do myself. Sounds like my weekend project this coming weekend.
http://www.tvmadeez.com/press_gauge/pressgauge.html
http://www.tvmadeez.com/press_gauge/pressgauge.html
Racer
Joined: Apr 2000
Posts: 299
Likes: 5
From: East Haven, Ct
Trans slipping
Good site I found looking at torque converters.
http://www.transdepot.net/4L60E_c_22.html
http://www.transdepot.net/700R4_c_9.html
http://www.transdepot.net/4L60E_c_22.html
http://www.transdepot.net/700R4_c_9.html
Last edited by LUDS 96; Aug 10, 2012 at 11:43 PM. Reason: add link
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