Standard torque converter lockup issue questions

[Mounce]

SO, torque converter solenoid or something is failing. Cruising at 60 it goes in and out of lockup needlessly or doesn't lockup at all. Slippage shown from watching lockup values shown on torque, even when it does lock it still slips 30-100 rpm it seems unless you let off the gas. Can also feel/see rpm differences when it goes in and out. I don't know a whole ton about the torque converter side of the trans so here I am.

I know everyone recommends the shift kit "code buster" whatever they call it avail from eBay that also removes tcc pwm / fixes lockup issues.

However, I DO NOT particularly want a shift kit or any mod to how the trans shifts or anything. This is, after all, my mom's car and a family vehicle as most of the regulars know, I just work on it and drive it here and there.

How do you go about fixing a lockup issue by itself? I can't find much info online about the issue other than people complain of the issue without much about the fix.

Now for a while the 1-2 shift has been harsh when cold. I imagine the "shift kit" will fix that but I'm mostly worried about the lockup issues at the moment. If the harsh 1-2 is as big of an issue as the lockup and needs addressed immediately I am open to ideas on that.

*service history: trans "diy flushed" at 113k and cooler installed same time.*

 

[Capote]

Driving it and lightly tapping on the brake while keeping your foot on the gas at a steady speed will confirm if there's a lock-up issue. Your RPM's will drop and then rise back up. You done this test to further your suspicions?

 

[Sparky]

The kit does not turn it into a tire chirping monster at all. Just slightly firmer maybe, but that's it. It isn't a performance shift kit, just a "fix the bad stuff" kit.

A snappier 1-2 shift when cold isn't that uncommon, mine always did that for the 100k I had it (both before and after the kit, no difference).

The only way to fix it is to repair/replace the TCC valve/bore. You could get the kit, and ONLY use the TCC valve pieces, and leave the rest alone I suppose. Just seems a waste to do that.

 

[Mooseman]

You could contact the eBay seller of the kits (name escapes me right now) and ask if they have a kit only to fix the TCC issues and also the 1-2 shift. I think they do have one that has the same as the big kit minus the Vette servo.

 

[Sparky]

You could buy just the Transgo SK-4L60E kit (it has the TCC valve repair stuff) and the proper separator plate and seals if you like. Just don't try to reuse your current plate/gaskets because the gaskets will tear and if you're in there it can't hurt to put the new plate in while you're at it.

I guess Sonnax has a TCC valve repair part, but it sounds way more involved to install (something about reaming out the bore, installing a sleeve, etc). Some say it is the proper way and the Transgo is a "quick fix" that shouldn't last, but, my experience is the Transgo is easy and does indeed last just fine.

 

[Mounce]

Driving it and lightly tapping on the brake while keeping your foot on the gas at a steady speed will confirm if there's a lock-up issue. Your RPM's will drop and then rise back up. You done this test to further your suspicions?

Oh yeah. Plus can watch / feel / hear rpm changes when it goes in and out. That prompted a ride with torque running and confirmed the lockup issue.

Thanks for the input guys, will do some more reading.

 

[Reprise]

You could buy just the Transgo SK-4L60E kit (it has the TCC valve repair stuff) and the proper separator plate and seals if you like. Just don't try to reuse your current plate/gaskets because the gaskets will tear and if you're in there it can't hurt to put the new plate in while you're at it.

I guess Sonnax has a TCC valve repair part, but it sounds way more involved to install (something about reaming out the bore, installing a sleeve, etc). Some say it is the proper way and the Transgo is a "quick fix" that shouldn't last, but, my experience is the Transgo is easy and does indeed last just fine.

^^^ This. Sparky nailed it. As he said, don't expect much difference in the 1-2 shift, unless you optionally drill out the separator plate to make it firmer, per the Transgo instructions.

Here's the link to the kit / vendor on eBay (1996-2006; I can't tell what year the OP's truck is from his profile page). This one has the HD separator plate, gaskets for same, and the good Sonnax pinless accumulator / forward pistons. It doesn't contain the Vette servo or the shift solenoids, and doesn't have the ATSC manual (the TransGo instructions are pretty good; just read through them a couple of times before you start, and reference them while you're working.) Skip the section on '2nd piston upgrades', unless you want to remove the 1-2 servo.

If you 'destroy' the original instructions (grease, fluids, etc.), there are copies online that you can d/l and print (or, make a copy of them before you start.) I 'dog-eared' mine pretty well when I did mine, going back & forth. It's not terribly hard - just take your time and figure on the better part of a weekend, if you don't run into any issues w/ breaking off pan bolts, etc.

I also second Sparky's rec on the TransGo vs. the Sonnax TCC valve remediation. The TransGo can be reversed / uninstalled. The Sonnax is a one-way operation, and it's way more difficult. Not to mention that the reamer is kinda expensive, and you only will use it once (the real value is if you are a shop / mechanic; then you can reuse the Sonnax kit on multiple 4L60s).

The one thing I fear is if the TCC bore has been excessively worn, which might be the case, given the description of the symptoms. You'll see when you get it apart, and you can head right to that section to check, once you get the VB removed (IOW...before you install the rest of the TransGo kit and discover that the TCC bore is worn (the valve should slide easily through the bore, but not rattle, and it should not be out of round). You could even check this before ordering the kit I linked above - although the truck will be down longer as a result (and you'll need to be careful not to damage the lower plate gasket, if you put it back together to drive, while you wait for your parts.)

If the bore is worn - then your best options are the Sonnax kit (b/c the bore is already larger), or to get a new VB - you can get rebuilt ones online, and some will have the Sonnax oversized TCC valve installed (this is the best way to go, I think - I'd rather have a shop install the Sonnax valve, if I went that route).

Finally, you may find others' kits cheaper on the Bay - the one I link above is about $130. It's well worth it to get everything you need in one kit, I think (e.g.; I'd pay a few bucks more, but not 100% more for the same parts). CTPowertrain is the vendor we've been getting these from. 'Orange' box is the one you want to correct issues - the 'Blue' one is the 'performance' shift kit.

If you really want to go 'all out', you can replace the steel checkballs w/ Torlon ones (they're cheap). But you'll have the hardened separator plate, so the steel ones can be reused (unless you find one has punched through your existing plate, which I *don't* think will be the case; your issue seems to be solely with TCC lockup).

 

[Sparky]

Even with a worn bore the Transgo fixes it. That is what causes the problem in the first place, and the Transgo fixes that. My 4L60E in my Camaro couldn't even stay in lockup anymore, but it still wasn't out of round and the Transgo fixed it. I doubt his is out of round at this point as it still works, just kicks in and out.