4l60e wont shift into second at WOT
08-12-2013, 11:09 PM
#1
4l60e wont shift into second at WOT Let me explain my problem and tell you what I've done.
I've built a bunch of 4l60's being a GM trans tech for several years and never had a 4l60 come back with a problem so I know what I'm doing (I think, not sure now)
I have a 99 s10 with an ls1 swap with a trans that I just built. I used to have the original 4l60e behind it but knew it wouldn't last long. I'm going on drag week with the truck so thought I would upgrade to 4l70e. I found a 2002 trailblazer 4l60e and took everything out and bought GM 4l70 planetaries, sonnax smart shell, and sonnax sun shell, hardened output reman valve body, new clutches and zpack, new trans harness, solenoids, band, drum, Vette servo, and Yank 3600 converter.
When I drive it normal it shifts fine. When I floor it, it will not shift into second without going off the rev limiter several times. Also when going 55 or so and mash it, it goes off rev limiter again. I pulled the trans and see no sign of anything burning, everything still looks new. The 2-4 servo pin is the proper length and I double checked the seals in the 2-4 servo.
Took it to a buddy of mine who has been building race units and also a trans tech for GM and he looked it over and thought a valve was sticking, so we cleaned the valve to where it slid good, re air checked everything while it was apart and all was good. I put it back in and same thing. Next, I put in the valve body that originally came with the trans and still same thing happens.
I have a friend who tunes and he tuned it. He uses HP tuners and set the shift point at WOT to 33 mph and 5000 rpm and set it to shift off of rpm to see if it made a difference and it didn't. Rev limiter is set to 6500. Tire size and rear gear is correct in HP tuners. You can see it commanding 2nd when logging in hp tuners but nothing happens
I did unplug the maf and it made no difference either. My next step I guess, is to test line pressure.
Anybody have anything similar to this? I'm going NUTS. If its not working first of next week I guess I'll order one with a guarantee. Drag week is coming quick and I'm still planning on doing heads and cam.
I've built a bunch of 4l60's being a GM trans tech for several years and never had a 4l60 come back with a problem so I know what I'm doing (I think, not sure now)
I have a 99 s10 with an ls1 swap with a trans that I just built. I used to have the original 4l60e behind it but knew it wouldn't last long. I'm going on drag week with the truck so thought I would upgrade to 4l70e. I found a 2002 trailblazer 4l60e and took everything out and bought GM 4l70 planetaries, sonnax smart shell, and sonnax sun shell, hardened output reman valve body, new clutches and zpack, new trans harness, solenoids, band, drum, Vette servo, and Yank 3600 converter.
When I drive it normal it shifts fine. When I floor it, it will not shift into second without going off the rev limiter several times. Also when going 55 or so and mash it, it goes off rev limiter again. I pulled the trans and see no sign of anything burning, everything still looks new. The 2-4 servo pin is the proper length and I double checked the seals in the 2-4 servo.
Took it to a buddy of mine who has been building race units and also a trans tech for GM and he looked it over and thought a valve was sticking, so we cleaned the valve to where it slid good, re air checked everything while it was apart and all was good. I put it back in and same thing. Next, I put in the valve body that originally came with the trans and still same thing happens.
I have a friend who tunes and he tuned it. He uses HP tuners and set the shift point at WOT to 33 mph and 5000 rpm and set it to shift off of rpm to see if it made a difference and it didn't. Rev limiter is set to 6500. Tire size and rear gear is correct in HP tuners. You can see it commanding 2nd when logging in hp tuners but nothing happens
I did unplug the maf and it made no difference either. My next step I guess, is to test line pressure.
Anybody have anything similar to this? I'm going NUTS. If its not working first of next week I guess I'll order one with a guarantee. Drag week is coming quick and I'm still planning on doing heads and cam.
08-12-2013, 11:54 PM
#2
Moderator
My first thought was the servo pin length, but you say it is correct and you obviously have built a bunch of these. A quick check is to put a crowbar on the servo cover and measure/estimate how much it can move in. About .075 is perfect, much over .150 and the band might start to slip.
Next, I wonder about the boost valve, especially because you have mixed parts from significantly different years. If you take a boost valve from a 2007 and stick into into an earlier trans, the pressure will be very low because the 2007 boost valve and sleeve are shorter. Look up the Sonnax 4L60E-LB1 and -LB2 instructions to see details.
If the boost valve is the correct one for the pump year, I would also next hook up a pressure gauge, and check the pressure when the shift occurs.
Next, I wonder about the boost valve, especially because you have mixed parts from significantly different years. If you take a boost valve from a 2007 and stick into into an earlier trans, the pressure will be very low because the 2007 boost valve and sleeve are shorter. Look up the Sonnax 4L60E-LB1 and -LB2 instructions to see details.
If the boost valve is the correct one for the pump year, I would also next hook up a pressure gauge, and check the pressure when the shift occurs.
08-13-2013, 12:13 AM
#3
Forgot to mention the boost valve. I put in the .500 boost valve that came with the vette servo kit. I used the Jtool on the servo pin and it was on the tight side of the hole. I'll check the boost valve and make sure it's the correct one they sent me.
08-13-2013, 05:36 PM
#4
Moderator
Here are useful illustrations for the Sonnax boost valves:
http://www.sonnax.com/system/instruc...LB1-LB2-IN.pdf
Notice that the newer style pump (iirc 2007+) takes a shorter boost valve. If you use the shorter boost valve in a pre-2007 pump, you will have very low line pressure.
Also the Transgo boost valve comes with a thick aluminum spacer. If you forget the space in a pre-2007 pump you will have very low line pressure. Conversely, do not use the spacer in 2007+ pump or pressure will be too high.
http://www.sonnax.com/system/instruc...LB1-LB2-IN.pdf
Notice that the newer style pump (iirc 2007+) takes a shorter boost valve. If you use the shorter boost valve in a pre-2007 pump, you will have very low line pressure.
Also the Transgo boost valve comes with a thick aluminum spacer. If you forget the space in a pre-2007 pump you will have very low line pressure. Conversely, do not use the spacer in 2007+ pump or pressure will be too high.
08-13-2013, 06:58 PM
#5
Small update, hooked up pressure gauge and pressure stayed at 70 psi. In gear, reverse, park neutral, d1, d2, d3 etc.. Revving in gear got same pressure didn't matter what I did same pressure. Pulled trans connector same pressure. Looking like pressure control solenoid or pump issues. Picked up epc at work and will go out now and put it in and check length of boost valve while Im there.
08-13-2013, 10:52 PM
#7
Moderator
Glad to hear that you got it working!
Interesting that you tried two valve bodies, but perhaps you used the same defective EPC with both.
There have been quite a few threads here about problems caused by defective EPC solenoids. I know some builders replace them before anything else.
Interesting that you tried two valve bodies, but perhaps you used the same defective EPC with both.
There have been quite a few threads here about problems caused by defective EPC solenoids. I know some builders replace them before anything else.
