grasshopper645

I am doing my own rebuild on a single piece 4l60e 1997 model from a z28 camaro (broken drive shell, no other issues). I have done extensive research and taking months to do it, I have a couple of questions regarding the TCC regulator fix.

1. At approx. 130k miles, would you say its a smart move to do a TCC regulator fix even though I've had no symptoms of failure or p1870 codes occur.

2. Can someone please explain the negatives of doing the spring mod as opposed to using the reamer and oversized TCC regulator. I understand I will loose the partial lockup feature, but I don't quite understand what this means. The torque converter lockup is on/off as opposed to partially engaged? - What are the disadvantages of this? worse fuel economy? worse shifting? Will I get any fault codes as a result?

3. If I do the proper repair and use the reamer with oversized TCC regulator, what happens when the boar wears out a second time? will the valve body affectively need to be replaced when the transmission eventually fails again? (hopefully 20+ years from now but still curious)

TIA

sjsingle1

iTrader: (1)

i have never had the dreaded p1870

but i bought a reamer and put in a over size sonnax valve in all my trannys.....its not a question on if you will get 1870.....but when

the oversize valve keeps excessive leakage past a worn valve bore

i always like to do it right the first time....the right way

i am no tranny expert ....but i did stay at a holiday inn express last nite

MaroonMonsterLS1

Best bet for simplicity sake is to get a transgo SK4l60e kit and use their TCC regulator valve. its about .0005-.001 larger in diameter than the stock valve. Usually slips right in the bore and cures the leaks.
I would also use a set of sonnax o-ring'd end plugs to help cure leaks.

As for the "spring mod" you are just blocking the tcc reg. valve outboard. You can do this with a coil-bound spring, a spacer of some sort (copper tube), etc. How the regulator valve works is not all that complicated, but the gist for you to know is that by blocking the valve outboard, you are forcing max pressure to the Torque converter clutch whenever the TCC solenoid is "ON" essientially bypassing the PWM valve for tcc. So, you turn the lockup to just "OFF/ON" rather than the smooth (read: slipping) engagement with the pwm valve.
Blocking the valve outboard is the best method because it eliminates the valve oscillation which is the root cause of the bore wear. So once the valve is blocked, it will never develop any more bore wear because it can't move.

MaroonMonsterLS1

I should go on to mention, that some builders that do this have expressed issues with TOO MUCH pressure in the torque converter clutch piston. This can cause it's own issues. (Cracked TCC piston, accelerated wear, vibration, rough engagement, etc)
I personally have not had those issues but I want to, in the interest of full disclosure, give you the info so you can do your own research and make your own decision.

PBA

I use the TransGo PWM eliminator valve in everything that I have built and in all of my rebuild kits. The PWM eliminator valve changes if from a pwm to a on/off setup as in the 1993-1994 4L60E's and all 700R4's. Easy to install and no special (expensive) tool required for installation. So far I have not had a complaint in the last 20+ years since I've been doing this.

MaroonMonsterLS1

This is the valve that comes with their SK4L60e kit correct? And also the HD2?
Blue spring inboard, new valve outboard.

grasshopper645

Thanks very much everyone! This has helped me greatly. I am thinking that I will retain the PWM feature, and in 20 years or so once the boar wears again I will either do the spring mod or obtain a new valve body..

One other question, does the PWM feature require any sort of special torque converter? I am looking at purchasing a new one and trying to work out if I need to look for anything specific or weather any generic 4l60e compatable torque converter will work.

MaroonMonsterLS1

The clutch linings do change for PWM vs non PWM

Just make sure to discuss with whoever/wherever you order your converter.

PBA

For the price of the damn tool that you need to do the Sonnax stuff, you could buy another valve body and/or install the complete TransGo kit with the pwm eliminator valve for less, and you can use any type of clutch material for lockup in the torque converter. Yes, that valve comes in all TransGo kits. Install blue spring first, then the valve.

sjsingle1

iTrader: (1)

yes that tool is pricey !!!! .....and the cheaper of all the reaming tools they offer

grasshopper645

I agree its stupid expensive, but I want to retain the pwm feature for better fuel economy and smoother engagement. You can buy used valve bodies but you really don't know how warn the bore is which means i'd be in the same position I am now..No issues with the valve body but the 'what if' and most trans specialist saying you should do one of the repair options or you'll be pulling the valve body again.

coryforsenate

iTrader: (1)

I paid a transmission shop $10 to ream my TCC bore to use the Sonnax P1870 fix where PWM is maintained. No way was I going to spend over $200 for the two reamers required to install the Sonnax kit.

To be fair, Sonnax does say they're really intended for shops who will use them regularly and not the guy who'll use them once or twice in their life.

MaroonMonsterLS1

You'll be the first guy I've ever heard actually WANT the pwm for tcc. It raises temps, increases wear, and feels soggy.
But to each their own. If it were me, I would call local shops and see if one of them would ream the bore for you so you can use the sonnax valve

coryforsenate

iTrader: (1)

I made the call when I was first learning about transmissions during my first rebuild. Figured it's my daily driver, let's keep it kinda close to stock. Today, I'd probably go to on/off for TCC.

grasshopper645

Hmm really? At the end of the day i'm just a complete amateur but have not really had any decent pros of switching to on/off pwm aside from 'its cheaper' (which is a valid reason obviously)

grasshopper645

This is the exact situation i'm in, thinking to keep it stock. Why would you go on/off now?

bbond105

It raises temps, increases wear, and feels soggy that's why.

coryforsenate

iTrader: (1)

I've been a part of this forum three years now and I respect the opinions of the experienced builders that I've interacted with on here, like pba, maroonmonster, mrvedit, and bbond. I think all but mrvedit actually make their living doing transmission work. If they say having the TCC on/off is a better call in pretty much every situation, I trust them.

grasshopper645

OK so slightly reduced fuel economy is the only real disadvantage then? I wont get any PCM codes? Is a PWM torque converter backward compatable?

grasshopper645

This is as good a reason as any for me