700R4 Again?

[Subzilla]

I'll try not to make this too long. My '83 with the rebuilt 700R4 is misbehaving again with only 16,000 miles. It shifts through the gears to overdrive but then only half way goes into final lock-up. I say half way because the rpm's jump when I hit the brake pedal (unlocking) and at cruising speed the rpm's fluctuate with pedal position, in other words, it's slipping. Where before in lock-up mode, there was no change in rpm's with pedal position unless a downshift occurs or the vehicle changes speed. I had a long debate with the local transmission shop, the best in town, about this (I bought the transmission from them). They say it is locking up and when I press the pedal, the rpm's are suppose to raise. I say the rpm's won't change this much and it wasn't doing this 3 days ago. They also say there is no way it can slip in final lock-up; it is either locked up or not - no in-between. I'm not trying to make them warranty this and I told them I would pay them to fix it but they just don't think there is a problem. It was left at I'm the psycho customer that they don't believe but they would call GM to see if something like this could ever possibly happen?!? I'm suppose to call them back this afternoon. It's funny how some shops think they know so much more than any customer could possibly know, especially about their own vehicle.

Any suggestions as to my problem - with the transmission and not the shop! Oh, the Amsoil syn. trans. fluid is bright pink and the problem occured after 10 minutes of driving the first few times but now is constant.

[Subzilla]

Adding to my post: I replaced the IP in March and just re-installed the TPS in the same location. No change in shift points but I did notice the transmission now stays locked while coasting where before the rpm's would drop back close to idle while coasting. Could a malfunctioning TPS or the brake switch be sending half a signal to the transmission?

[Salemone]

It seems your torqe converter clutch might be glazed. It is a common problem. Before you do anything drastic put a pressure gage on the trans
and drive it around for a while. Make sure it gets hot. Any 200lb gage will work--use 1/8 copper
tubing temporary thru the door seal for the gage.
I have permanant gages in all my cars. If the pressures are good then its the converter.I am very familiar with this problem. My phone # is
(909)947-9916-- John

[CleviteKid]

You probably have just two wires going to the 700R4 on the left side. Splice some leads into these and bring them into the cab, along with the tubing for the pressure gage. Then put either a voltmeter, or a 12v light bulb between the wires. You should see about 13V, or a brightly lit bulb, when the lock-up signal goes to the tranny, and 0.000 volts, or a dark bulb with no signal. Anything inbetween is not allowed, and would indicate an electrical problem.

If the electrics and the pressure is good, you may indeed have a fried converter clutch.

Dr. Lee :cool:

[mhagie]

The tps switch is probably slightly out of adjustment, or it would still unlock the converter when throttle is in idle position.
Personaly on my truck I jumpered the wires together to keep converter locked untill downshift I don't like the idea that every time you let up on throttle the converter unlocks.
Merle

[Subzilla]

UPDATE:
With a "neverending willingness to help" attitude of one of our California members named John, I was able to diagnose and repair the culprit to my slipping torque converter lock-up. It turned out being the converter itself, not too big of a suprise. Pressure and electric stuff was all checked and OKed before R&Ring the converter (lots of fun). John assisted me through many, many of my phone calls and even told me the exact place to purchase and the exact part number of a more suitable, durable TC. Subzilla runs as it did before with the locking TC but I've got some shift point tweaking to do with a governer recalibration kit. Again, my DP membership paid for itself, financially and mentally, through a coast-to-coast (NC-CA) relationship with "Dr. 700R4". I did appreciate the other responses and advice received. My wife thanks you too as she is tired of my grumbling about the local transmission shops!

[jcomp]

So what where was the place and what was the part number? smile.gif

[jcomp]

Um... ignore the first "what"... :rolleyes:

Are posts editable after submission?

[john8662]

yes, you can edit a post after it is posted, just click on the paper and pencil icon at the top of just your post, it'll take you to an edit box. Thats it!

[Subzilla]

Got it from ATC, a national transmission parts chain. I think they are changing thier name to something like Axiom Automotive. The TC was a GM33 - it's a non-woven carbon fiber type built for a police caprice. They (ACT) raised an eyebrow when I told them what I was putting it in but this particular counter person seemed to be more of the "look it up in the application book" variety and less of the "first hand knowledge about the specific part" variety. I'm relying on John's research and expertise for this selection as I am by no means a transmission expert.

[jbell]

I'd like to upgrade mine, but couldn't find any info on gm33 on the internet. Got additional info?