anyone using 4L70E out of TBSS?

[Tango68SS]

Guys,

I have a 4L70E out of an '08 Trailblazer SS... It has a very soft shift pattern... What have you all been doing about upgrading this tranny or should I just trash it and start with something else? I know I can wake it up with a new higher stall converter, but what else can be/ should be done?



TC

[rocketrod]

Hey stranger! I am using one, but you know that. I have been wondering the same and curious to see what people recommend, although RPM Transmissions isn't far from so I will probably give them a call and see what they recommend. You may also want to contact Travis as I know he has had a few of these upgraded.

[Tango68SS]

Hey stranger! I am using one, but you know that. I have been wondering the same and curious to see what people recommend, although RPM Transmissions isn't far from so I will probably give them a call and see what they recommend. You may also want to contact Travis as I know he has had a few of these upgraded.

Right back at cha' Rod! How are you doing? How's your baby coming along? I have been driving the wheels off of mine! But lately I have come to realize that the tranny is the weak point... Though hindsight being 20/20 I should have gone with the T56... but, I love the convenience of the AT (especially with my bad knee) so I need to figure it out... Twist is right up the road from me in Daytona. I think it's time to take a ride to see Steve there...

TC

[MarkB]

The 4L70E is a good transmission when comparing it to a 4L60E. It has a input speed sensor that isn't really needed if your using most aftermarket controllers
The 4L60E can be built just as strong, but if we are only comparing OEM configurations the benefits over the 4L60E are:

* Increased horsepower and torque capacity (upto 400 ft lbs at the flywheel)
* Shot peened output shaft
* Heat treated spline on the pump stator
* Induction hardened input shaft
* Seven-plate clutch packs
* 5 pinion front & rear planetary gear sets

Weak points are as follows:
- Pump rotor & rings
- 3-4 clutch pack
- Input sprag
- Sun shell
- Forward & 1-2 Acc. pistons
- Input shaft to drum spline area
- Valve body needs a few calibration changes
- Clutch clearances refined for aftermarket applications
- Servo inprovements
- Along with a few other tricks
- If using a stock ECM a good tune with EPC adjustments is recommended or use a good stand alone controller to adjust to your preference.

They can be built, but have their limitations... They can be built to have a crisp & quick shift and handle more than the OEM 400 Ft lbs torque rating.

I hope this helps.

[Tango68SS]

Thanks Mark! It does! Trying to figure out if building this one or going with a -60E...sounds like this is a good candidate and there are a few "tricks" to making it viable. Again, I am not looking for a competition tranny, just a better, "firmer" one than I already have... gotta get the power-to-the-pavement!!

TC

[alocker]

http://www.tbssowners.com/forums/showthread.php?t=54565

[73z-6sp]

ybugtcv

[Tango68SS]

I too have the 4L70. It's the weak link on my build. I also wish I had gone with the manual t56 but...
Mine makes terrible noises but it shifts fine albeit soft like you said. It wants to shift too soon sometimes and too late other times. I'm still debating if I should get it built or wait and spend the money to swap to t56. I do love the cruise control that is so easy with this setup. And I also like the ease of auto shifting but sometimes I just want that better control of car that a manual affords. Keep us posted on what you decide?

Hey Aaron,

How've you been?! You've peaked my curiosity with your "cruise control" comment... Tell me more brother! That is one mod I definitely need to do!

TC

[rocketrod]

If you are not going to be running the car hard look at tuning the trans ecm shift points and line pressures adjusted. The tune the harness builder put on my trans ecm was for a 2008 TBSS, which does not shift correctly in a car that weighs 1200 lbs less.

[Tango68SS]

If you are not going to be running the car hard look at tuning the trans ecm shift points and line pressures adjusted. The tune the harness builder put on my trans ecm was for a 2008 TBSS, which does not shift correctly in a car that weighs 1200 lbs less.

Rod,

I did that last summer when I had the car tuned by Mike Norris... He did all the things you mentioned (see vid on ScreaminPerformance homepage)... I just think the tranny is going...

[73z-6sp]

hfjsfj

[70Uglybird]

I have a tbss, stock it sucked. A rpm trans spec type rebuild, tune, and converter woke it up considerably. They have. Better input shaft than a 4l60e. 4l80e is needed for big power.

[rocketrod]

I have a tbss, stock it sucked. A rpm trans spec type rebuild, tune, and converter woke it up considerably. They have. Better input shaft than a 4l60e. 4l80e is needed for big power.

What level trans did you go with, what stall and what kind of engine mods have you done?

[70Uglybird]

I went with level 6 I believe everything but the upgraded shafts. 3200 stall, and just boltons...4 inch fenderwell intake. Electric fans and brake duct tranny cooler. Really changed the truck with negligible effect on drivability.

The tbss's tear up these trannies at relatively low hp because they are so heavy.

[Tango68SS]

Well boyz,

Not sure what I'm going to do... On my way home today from work, the car went into limp mode due to "Powertrain" code P0641... Luck would have it, I had my trusty OBDII reader and app on my phone... cleared the code;got her out of limp mode; worked my way home... In a 15 mile drive, she went into limp mode four times! (frustrating)... Since the Chevy dealership is between me and home, and I have used their "best 'vette mechanic" before, I limped in... Now I sit here waiting on the "damages" estimate...

Luckily this dealership has a race team and LOVES my car (brought it here once for a weird code read on an injector)... They are going to flush the tranny and check the TCM to see if everything is kosher... hopefully this will keep her in drivable mode for a few months...

BL: looks like I now will be getting this -70E upgraded...

[73z-6sp]

ghfghsfh

[Tango68SS]

Hey! I'm good! Just busy with a 4.5 year old!

I'm not sure which harness you are using. I have the speartech harness with factory ECM and TCM. There are a few wires that need inputs to make the cruise work.
Attached is a wiring diagram.
Link and info I used:

http://67-72chevytrucks.com/vboard/s...ght=DBW+cruise


I used three relays to make mine work properly using the Dakota Digital cruise switch. One is because I have LED tail lights and without the third relay my cruise was not working correctly. Let me know if I can help with anything.

Aaron

Attachment 75264

EXCELLENT post Aaron! Thanks!

BTW, I got my car back from the "stealership" last night.... It turns out that it was NOT the tranny or TCM.. After four hours of diagnosing, it turned out to be a sensor (oil temp/press) was shorting-out against the bellhousing... New sensor and 'viola! car runs again without going into limp mode... Since I originally thought it was the tranny, they flushed and serviced it while in there... I really gotta get smarter on these "computer" cars...EXPENSIVE EDUCATION!!

TC

[73z-6sp]

gfhfghsfh