GM Guys, School Me On Torque Converter Replacement

1995 Chevy G30 1-ton van, 350, 116k original miles, 60k on re-manufactured transmission replaced under warranty. I've owned it for the last 6 years and put 46k trouble free miles on it. Has developed a "shudder" about 50-60 mph or so, like driving over rough road when I'm not. Seems to be getting more pronounced. Leads me to believe torque converter. 4L80E transmission (17 bolt pan).

I am fairly mechanically savvy, but have never replaced one, or r&r'ed a transmission before. Cannot afford the labor to pay someone else to do it. Would appreciate any tips, suggestions, warnings, advice you can offer before I tackle the job. I am also uncertain of what converter to get. They seem to range in price from $99 to over $1K, I'm lost on this.

Thanks in advance.

 

Let’s talk about how you determined it to be a converter? I would imagine it would be RPM dependent and not road speed dependent if that was true. Also something that you may or may not know is that some of those older trans have electronic lockup converters. I’m not sure how it determines when to lock it but probably RPM and load. If it’s afting funny I think you would experience a shudder like you describe.

 

Should have worded my post differently. After researching the symptoms, I believe it is the torque converter, but not sure. This is a lockup converter. Thanks.

 

Sounds like a lockup clutch issue.
Have you tried driving it and when the shudder happens touching the brakes? If it's an electronic lockup usually they unlock when the ECU sees brake signal.

As for removing the tranny, a good manual or YouTube videos will help.
Get the thing up on blocks as high as you can. Unbolt driveshaft and get it out of the way. Unhook all the wires and mechanical linkages.
Support tranny with jack. Remove the bellhousing bolts. Remove rear mount and crossmember.
The hardest part is usually so PITA to get to bellhousing bolt.

Also you may want to check and drain your fluid. Drop the pan as well. If the clutch is really coming apart bad the tranny guts need cleaned. Maybe Best to look for new one.

 

Being an old van this should have a nice big dog house to remove and get those bell housing bolts. Only thing I'd add to this is the exhaust might be troublesome. IMO sometimes it's easier to just sawzall off a chunk and rewelded it (I have a welder so easier for me then if you don't) then to try and fight with rusted/rotted bolts.

 

Never seen converter shudder on one of those....Typically they only shudder for a breif time as they lock up and not for a sustained period of time.
If it is it will go away if you touch the brake with your left foot while maintaining with your right foot....
Make sure the ujoints and carrier bearing are okay....

 

It is an electronic lockup converter, get a schematic and snip the wire for it (if it's not on its own molex) and test drive. No shudder, bad lockup clutch or hydraulic circuit (could have a bad solenoid in the transmission that's not opening fully or quickly enough to give full fluid pressure to the lockup circuit).

 

Awesome. Will do some more diagnosis and see what I find. Thanks for all the replies!!

 

Also, if it is converter shudder it also needs valve body/ and pump updates or the new one won’t last. The valves and end plugs in the pump wear and cause pressure loss in the tcc oil circuit causing the clutch to slip/ shudder.

 

I'd snip the TCC wire and leave it as is before I'd stick that much money into a 95. Fuel mileage will go down a little but unless your driving across country who cares? The TCC is there to solidly lock the engine and transmission much like a standard trans does, by removing this you'll have a little more viscous slippage and thus will run a bit higher rpm whist cruising, maybe a few hundered RPM. Like I said, IMO it's not worth the hassle. If you determine this is the issue, try it disconnected for a little while, you might be able to make a more informed decision from that observation.

 

There is a band-aid additive you can put in the ATF that reduces shudder.

<edit> I found the tube I have. It is Lube Gard Instant Shudder Fixx.

A '95 van has the computer-controlled transmission.

 

That is what my transmission guy told me a couple of years ago, and he has probably worked on every type of A/T that has been sold in the US.

 

It will overheat the transmission though if you cruise on the highway with the converter unlocked. Not a good long term solution.

 

On both the 700R4/4L60E and 200-4R the fluid level is cut way down in 4th gear. Driving withoutthe TC locked up with overheat the gears quickly and burn your trans. Im not sure on the 4L80 but I wouldn't risk it. Simply holding the brake pedal a bit while driving will keep the TC unlocked to diag without killing the trans in the process.

 

You've obviously never met a WERA Vintage racer then...

 

You might find a shop that will run a BG transmission flush. The machine flushes your transmission while your car’s in the air, with your engine running and trans in gear. Cleans everything inside including torque converter. I’ve had transmissions behaving badly fixed by this.

 

Who fed you that Line of crap???
Driving without the converter locked up damn sure won’t hurt a trans. Hell it is actually better for it as rpm is up and so is line pressure. The big killer of those tranmissions is lack of line pressure at low RPM from locking the converter up and going into high gear at 1200rpm!!kills the three/four clutches.

 

Sorry guys have to chime in here.
Cutting the lockup wire will burn uour unit up. It completes the lube circuit
Now on a 4l80e chances are you may get lucky and it only be converter but the solenoid for lockup cause these issues as well.
Also low pressure can also.
And these units have Pressure regulator issues in pump.
So getting a ban aid fix may cost you more in long run.
Now i do know some are just wanting to help out here.
But some of adivce is just bad advice.
And never let them flush a unit.
Its used to polish off the unit so it can be sold for a rebuild.
Remembr this 1 thing if you never remember anything about transmissions.
Nobody ever does anything to a transmission until they are having issues.
90% of the time its too late to fix.
But there are a few that will be simple but shops dont make money doing easy fixes.
No money in it.
Any questions just message me.
Steven
Advance Tech Transmissions
281 536 3330
In bussiness since 1987

 

If you really think the couple hundred rpm gain with a stock converter being unlocked really gains that much line pressure then ok, but line pressure doesn't mean anything when the planetary fluid circut isn't complete. That's why they sell lube valves, and it requires a non-lockup converter to be used as well.

 

Plantetary Fluid Circuit?? I’m guessing you are talking about the lube circuit. That has nothing to do with the TCC circuit on a 4L80. Saying that driving with the TCC solenoid always off will cause issues is wrong. What is the first thing that happens when you put one of those trnnsmissions in tow mode? Any idea?