4L70E no second gear *update #2 Fixed!*
4L70E no second gear *update #2 Fixed!* First of all I'd like to thank the people who took the time to read my post ! Now to the main topic. It is a 2006 TBSS drove it home fine then after start up I went on a run to the store and notice that 1st revved to 4k then shifted. After the vehicle warms up it shifts around 3k or 20-25 mph but noticed that it hangs in 1st til 3-4k RPM then shifts straight to 3rd. I can manually select 2nd and it acts just as if I apply it to go in neutral it just revs up no slip what so ever. Trans shifted perfect before this happened. Trans has every gear besides 2nd. Reverse is great and 4th holds very strong under WOT top speed rolls from 65+. Talked to a few shops and TBSS owners and most say it's something with the 1-2 accumulator but never messed with Autos I've only owned t56 mounted cars.. Any help guys !? I will drop the pan and see if I can locate a cause for the issue within the next day or two. Thanks!
Last edited by 427TTA4; Oct 30, 2014 at 08:10 PM.
TECH Junkie
Joined: May 2012
Posts: 3,050
Likes: 716
From: Poplarville, MS
Once you have the pan off you can remove the 1-2 accumulator housing and check the piston and springs. The plastic pistons break all the time. You can also check the band apply servo pin travel. This is on the right side of the trans, just behind the bell housing. Too much travel indicates the band is worn out. You can lengthen the pin or replace it with a longer one and get a few more miles out of it.
Check out this thread.
https://ls1tech.com/forums/automatic...cond-only.html
Check out this thread.
https://ls1tech.com/forums/automatic...cond-only.html
Moderator
Joined: Aug 2010
Posts: 7,323
Likes: 529
From: Ann Arbor, MI
Drop the pan the remove the "dome" shaped 1-2 accumulator which only requires removing three bolts. A severely cracked piston could cause loss of 2nd gear.
A bad seal on the 2nd servo piston could also be the culprit.
From what you have said, it doesn't sound like an internal/major problem that would require removing the trans.
A bad seal on the 2nd servo piston could also be the culprit.
From what you have said, it doesn't sound like an internal/major problem that would require removing the trans.
Thanks for the quick reply guys! I'm actually going to pull it today in about a few hours from now. Will keep everyone updated on what happens later and what was the cause "If I can find it". Hopefully it will help someone else in the long run hate seeing all these treads without comming to a conclusion to the problem!
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Verdad Gallardo Moderator
Joined: Aug 2010
Posts: 7,323
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From: Ann Arbor, MI
You probably should follow bbond105's advice and measure (at least estimate) the end play of the servo by pressing on the cover to determine how much it moves.
installed a Sonnax servo pin #77787-02K and a corvette servo while I was in the process and now 2nd shifts fine !!! Goes all the way to redline with no problem but I will stay off of it. I know I am on borrowed time mean while I'll try to build my 4l70e or if I get convinced enough I'll swap a 4l80. Big thanks to all of your help ! I also installed a billet acumulator cover while I was inside but I doubt that was what fixed the issue!!!!
I actually installed it and tried to see how much play it had and is was around an 1/8 so I left it as it is...I had around 1/4 or so of play before the pin swap.
Moderator
Joined: Aug 2010
Posts: 7,323
Likes: 529
From: Ann Arbor, MI
And congrats on getting your trans working.
I'll bet you learned a lot and are much more comfortable with these beasts now.
Thanks!! I actually did learn a lot since I only owned and worked on 6spds... If an auto started to act up for example slip or just not go in a gear I'd call it done ! And get a new one.. but not anymore !! Thanks again sir and the rest that helped !!!