Built 4L70E AWD TBSS

[posenheimer]

I figured I would ask here on the forums for anybody that tunes built transmissions:

How do you guys set up your tuning? I have the torque converter stuff setup just fine, I was instructed by the Tranny rebuild kit sales company to zero out "shift firmness tables" looking at the tune, I returned all of that to stock, assuming that was what he meant. I put the shift speeds back to stock. I had 50% TM in the tune when it was stock, but the tranny still failed on me.

I assume the shift kit is doing most of the work of increasing the shift firmness via line pressure, Would shortening up the shift times hurt anything? I am half tempted to leave 100 percent of the torque management in the tune to make this bastard live forever. I have tuned 4lXE way more aggressively than I had in the TBSS but it still failed. Looks like it was not rebuilt correctly though. Accumulator bore was reamed without an oversized piston and it was sloppy in there from what the tranny builder is telling me.


Any advice / insight is greatly appreciated. Thanks guys and gals

[93camaro_zzz]

I would be interested in this too, as I have an AWD TBSS also. Mine is cam, LTs, custom exhaust, CAI, efans, LS7 MAF, and a 3600 stall. I left my torque management in the tune for sure, because I am so scared of this shitty 4L70e against the much increased power, pulling this heavy pig. I have a feeling I am on borrowed time with it. Luckily the wife mostly drives it.

[motorheadmike]

There has been absolutely no help in the matter, ever, on the forums. Those who claim to know don't share because it isn't profitable.

My TBSS has been sitting since early Oct 2016 thanks to a bunch of crap customer support:
http://www.tbssowners.com/forums/4l7...l-5-today.html

Your best bet is install a 4L80e and move on with your life.

[brandon6.0]

^^^ Yes exactly!! I love my 80e swapped tbss.

[93camaro_zzz]

Yeah, but I hear the 4L80e swap is a nightmare on the AWD models. And I am not one of those guys that convert their cars to RWD. Sorry about your luck with your trans motorheadmike. I would be just as pissed off, knowing how much those things cost.

[motorheadmike]

Yeah, but I hear the 4L80e swap is a nightmare on the AWD models. And I am not one of those guys that convert their cars to RWD. Sorry about your luck with your trans motorheadmike. I would be just as pissed off, knowing how much those things cost.

Being Canadian I don't like the idea of going without my AWD either, and I have done full business case for both options the costs are high regardless. However, if you need any further reason to run far far far away from the 4L70E: http://www.tbssowners.com/forums/4l7...ping-help.html

[9secZO6]

What specifically failed? What accumulator, 1-2 or 3-4? That unit can hold a lot of tq when built right, but will still suffer from 3/4 clutch failure after several hundred passes. Best you can do is use the Sonnax input drum with billet plate instead of snap ring, and use the trans-go vacuum modulator kit and shoot for 300psi line pressure with the hose off. I have units living for 2 years plus in mid 9sec f-body's that are around 3800#. Parts alone are close to 5k, so it does exceed the cost of a 4l80 conversion...

[posenheimer]

http://www.700r4l60e.com/store/produ...&cat=55&page=1

This is the kit I went with. I believe it was the 3 to 4 accumulator piston that failed. I added a 4th gear Sonnax servo for good measure.

[motorheadmike]

What specifically failed? What accumulator, 1-2 or 3-4? That unit can hold a lot of tq when built right, but will still suffer from 3/4 clutch failure after several hundred passes. Best you can do is use the Sonnax input drum with billet plate instead of snap ring, and use the trans-go vacuum modulator kit and shoot for 300psi line pressure with the hose off. I have units living for 2 years plus in mid 9sec f-body's that are around 3800#. Parts alone are close to 5k, so it does exceed the cost of a 4l80 conversion...

The root cause is still unknown as I have yet to tear it down. The trans had less than 12 passes on it. Thanks for the advice, but in a 5100+lb performance application it is fools errand to chase success with a 4L70E.