sonnax 4th gear servo issues
07-27-2014, 09:17 PM
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sonnax 4th gear servo issues
I am dealing with a mind boggling issue with my suburban.
We had a 4l60e built up, and we were using a Sonnax 4th servo.
So it was installed. All is great for a few weeks. We are driving down the freeway one day and we starting to get some surging in 4th. I originally suspected a the TCC was slipping because we also threw a P1870. We end up driving home (60miles) in D3. Throw on HP tuners, seeing 0 tcc slip with converter locked in 3rd. Seeing 200-300RPM slip converter locked in 4th.
So I am super busy, I drop the truck off at chpspecial's house because they built it. They pull the servo out and see one of the orings looks suspicious..
They drop in another 4th servo that is known good. We picked it up again.. Everything good. Confirmed no slip.
We drive it around the city for a week (every day). We make the freeway drive again and it ***** up again. Slipping 4th.
So i was reading that sometimes if the pin is not long enough there will be a no 4th condition (which is weird because I had 4th). We are using the stock pin and a vette servo. I pulled the servo assembly out of a trans I broke the output shaft on that was in my silverado. Measured out the pin and it was slightly longer. So I dropped that vette servo + the 'new' 4th servo back in since the seals looked in, wasent seized up etc. Go for a drive, still no fourth.
I put the original vette servo and the original pin back in and drop in a stock 4th piston.. and now 4th is much firmer than the sonnax servo ever was and no slip.. I am probably going to leave it like this.
Really confused. Maybe I need a much longer pin? The pin travel seems to be in spec with the vette servo.
Can someone confirm the 'correct' location for the washer. It was after the eclip up against the servo.
I am planning doing a sonnax servo on my new 60e build that is going behind my 6.2 swap in my silverado and I want to get this right.
We had a 4l60e built up, and we were using a Sonnax 4th servo.
So it was installed. All is great for a few weeks. We are driving down the freeway one day and we starting to get some surging in 4th. I originally suspected a the TCC was slipping because we also threw a P1870. We end up driving home (60miles) in D3. Throw on HP tuners, seeing 0 tcc slip with converter locked in 3rd. Seeing 200-300RPM slip converter locked in 4th.
So I am super busy, I drop the truck off at chpspecial's house because they built it. They pull the servo out and see one of the orings looks suspicious..
They drop in another 4th servo that is known good. We picked it up again.. Everything good. Confirmed no slip.
We drive it around the city for a week (every day). We make the freeway drive again and it ***** up again. Slipping 4th.
So i was reading that sometimes if the pin is not long enough there will be a no 4th condition (which is weird because I had 4th). We are using the stock pin and a vette servo. I pulled the servo assembly out of a trans I broke the output shaft on that was in my silverado. Measured out the pin and it was slightly longer. So I dropped that vette servo + the 'new' 4th servo back in since the seals looked in, wasent seized up etc. Go for a drive, still no fourth.
I put the original vette servo and the original pin back in and drop in a stock 4th piston.. and now 4th is much firmer than the sonnax servo ever was and no slip.. I am probably going to leave it like this.
Really confused. Maybe I need a much longer pin? The pin travel seems to be in spec with the vette servo.
Can someone confirm the 'correct' location for the washer. It was after the eclip up against the servo.
I am planning doing a sonnax servo on my new 60e build that is going behind my 6.2 swap in my silverado and I want to get this right.
Last edited by stevenc; 07-27-2014 at 09:23 PM.
07-28-2014, 12:11 PM
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Any inconsistencies related to the servo and 4th, are almost always due to pin length being too short. Your best bet is to follow the instructions for 2nd servo 77911-03K https://s3.amazonaws.com/sonnax-dev/...911-03K-IN.pdf
Gregg Nader
Sonnax Tech
Gregg Nader
Sonnax Tech
07-28-2014, 12:35 PM
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Gregg,
My biggest confusion is why we had 4th, and then it randomly stopped working twice. When it stopped working, it was abrupt. 70MPH cruise, and then bam no 4th and it would start surging in and out of 4th.
Its been solid with the stock piston on some long drives so far.
My biggest confusion is why we had 4th, and then it randomly stopped working twice. When it stopped working, it was abrupt. 70MPH cruise, and then bam no 4th and it would start surging in and out of 4th.
Its been solid with the stock piston on some long drives so far.
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