Hi guys,

I have a 2004 5.3 and a 4L60E that I just rebuilt (first time rebuilding an auto).
The problem is that right after the rebuild the 2-3 shift feels like a bump that jerks the car forward.
There are no problems with any other shifts, 1-2 feels nice and crisp.

The hydraulic part is mostly stock other than the sonnax line pressure booster kit.

From what I have read, it could be 3-4 clutch engaging while the 2-4 band is still engaged.
How can I fix this?

I have a corvette servo installed.
Servo travel is 0.080".
3-4 clutch clearance is 0.043" (borg warner 7 friction pack)

 

Did you leak check the accumulator capsule?
What is your 3rd feed orifice size?

 

I replaced the capsule when I rebuilt the trans. And I checked it after I installed it - no leaks.

No idea on the orifice size, I installed a new separator plate (GM 24241783) without any modifications.

 

band clearance and 3/4 clearance is fine.
A line pressure test would be a good idea.
With the corvette servo and that separator plate, I think you'll need to open up 3rd feed for best result.

 

As a side note...if you installed sonnax part # 77701-076, take it out and throw it in the trash.
That causes issues like this more than it solves any other issue

 

I ordered a pressure tester, hopefully will be able to do a pressure test in a couple of days.

What is the preferred size for that 3rd feed hole? I have a stock truck torque converter.

No, I did not install it.

 

Stock converter and corvette servo I would leave the 1-2 hole stock
2-3 to .110
band release to .093
3-4 to .110

 

Ok, thanks, will try to modify the separator plate.

 

MaroonMonsterls1 needs to confirm, but I think that leaving out the inner springs on the servo could also cause a bind. Presumably you did not leave them out and they aren't overly weak; just pointing that out.
Here are the drill bit sizes close to .110 and .093:
7/64 = 0.1094
#35 = 0.1100
3/32 = 0.0938

 

I didn't leave them out, but I'm not sure how to check if they are weak or not.

Thanks, but I'll be using metric drill bits anyway. Getting inch drill bits here is next to impossible.

 

Stock converter and corvette servo I would leave the 1-2 hole stock
2-3 to 2.8mm
band release to 2.4mm
3-4 to 2.8mm

 

I drilled the separator plate to the specified sizes, but the 2-3 bump is still there. Maybe it got a bit softer, hard to tell. Also noticed that 3-2 downshift is very quick and somewhat harsh.
I tested the pressure at idle and got 90 psi at "D" at idle and 110 psi at "R" at idle.
Looked at hptuners logs and they show that "Force motor current" is 0.96A at "D" and 0.98A at "R" at idle (both desired and actual).
Trans fluid temp was 180F.
Any ideas on what to check next?

 

Test pressure.
Need all ranges, at idle and at 1500-2000 rpm brake stall

 

I tried to test the pressures at higher RPM, but I can't get the RPMs to 1500 because the brakes won't hold and the tires start spinning (probably because of the 4.89 gear ratio). The max RPM I can get to is 1200-1300.

Here are the results (at idle)
P 85
R 115
N 85
D 85
3 85
2 85
1 85

At 1200-1300 RPM:

P
R 250
N
D 190
3 190
2 180
1 190

When the tires start spinning in "D", the pressure seems to spike to about 250 psi.

 

Did some experiments with hptuners. Gradually lowered 2-3 shift pressures at light to medium throttle until there's no more bump. However, if I drive with the windows open I can hear a clunk on 2-3 shift. Is that clunk normal?

 

I'd be watching the pressure gauge while driving to make sure you're not risking the life of the trans.
Lowering the pressure seems to be masking a mechanical issue.
With those feed sizes, I don't have any tie-up issues.
I would not be surprised if you had a decent leak in the valve body skewing your issues.

 

Thanks. I'll try to make a longer hose for the pressure gauge to check it while driving.
What is the expected pressure for a 2-3 shift at light throttle?

Valve body is a GM remanufactured one. I actually have an old valve body that I removed when I rebuilt the transmission, I can swap it in to see if the issue is still there.