2003 Tahoe 4l60e sloppy 1-2 shift

[JP_Property]

Hello. My new to me Tahoe has 168000 miles. The 1-2 shift seems to be sloppy shift flare and a little bump. It shifts better in tow haul faster and firmer. Should I change 1-2 accumulator?? Any harm in running tow haul all the time?? What should I do to prolong the life of the trans other than fluid change?
Thanks

 

[slacktide_bitog]

If your transmission doesn't have a drain plug, get an aftermarket pan that has one. This will make future ATF changes much easier

 

[JP_Property]

Thanks. I will look into that.

 

[xxch4osxx]

Sounds like the common "slide bump" that those transmissions are known for. I was told it is an easy fix, something you need to replace in the valve body if I remember correctly. Clinebarger would be able to explain it much better.

 

[maxdustington]

4L60: Legendary 1-2 upshift.

 

[clinebarger]

The 2-4 Band probably has quite a bit of excessive clearance & the Line Boost system is a little weak.

****If you decide to use my correction system.....Follow every step!****

Parts list......
TransGo separator plate part# 46-PLT-96
Corvette "093" 2nd Servo......HERE
Sonnax "long" Band Apply Pin.....HERE
GM Inner Servo Cushion Spring 8681195.....HERE
GM 2nd & 4th Accumulator Piston kit 24221919......HERE
GM 2nd Accumulator housing outer spring 24219942.....HERE
GM 2nd Accumulator housing inner spring 24220146.....HERE
Sonnax Line Booster Kit (.490" Boost Valve) Part# 4L60E-LB1....HERE

Directions & info to follow.....

 

[JP_Property]

Hello Clinebarger. I see you are in Fort Worth. I'm in Arlington. Do you have your own shop here in Fort Worth??

 

[clinebarger]

The object here is to Increase Clamping Power applied to the 2-4 Band during a 1-2 shift while getting rid of the "Slid Bump".....It's a delicate process that took several different combinations for me to get right on GMT800 4.8L/5.3L trucks & SUV's.

*Remove the 2nd & 4th Band Servo from the side of the trans case, I'm sure there are several videos on Youtube for this!
*Clean the dirt/debris out the bore, Mainly where the snap-ring rides in the case with a lint-free cloth/towel.
*Disassemble the Servo Assembly by removing the small E-Clip & spring on the end of the apply pin.
*Drive the Apply Pin through the 2nd Piston, Don't worry about damaging the piston as it will not be reused....The 4th Piston likes to "mushroom" the shoulder of the pin.
*Using a Vise & shallow 3/4"-19mm socket, Remove the snap ring from the 2nd Piston with an Awl or small flat blade. I use the socket against the steel cover with the apply pin removed instead of how it's shown in the below TransGo instruction sheet.
*Retain the Small Spring, E-Clip, Washer, Steel Cover, 4th Piston, Case Cover, Large Cushion Spring, And the Return Spring shown to the Left.

Servo Apply Pin Fitting.....
*Grind/Mill 4 oil exit notches in the Steel Cover as shown, This keeps oil from hydro-locking between the Cover & 2nd Piston rendering the Cushion Spring ineffective, Also helps 3-2 downshifts stay clean!
*Install GM 8681195 Inner Cushion Spring inside the original Cushion Spring with the Small end of the spring facing the steel cover.
*Using a vise.....Assemble the steel cover & 2 cushion springs into the Vette/093 2nd piston & install the snap ring.
*Using the instructions with the Sonnax Apply Pin as a guide....Grind approximately 1/8"-.125" off the tip.
*Assemble the Apply Pin to the 2nd Servo Piston with the small spring/washer/E-Clip.
*Assemble & Attempt to install the entire Servo Assembly MINUS ANY seals at this time! You can also omit the Return Spring for now!
*IF your able to get the Wire Retainer to seat into it's groove......
*With the trans in neutral, Try to rotate the drive shaft in BOTH directions, The direction with the most drag Overruns the Reverse Input Drum that the 2-4 Band rides on. You may need a strap wrench for this if you lack upper body strength.
*If you cannot install the Wire Retainer AND/OR you cannot rotate the drive shaft.....Shorten the Apply Pin in .030" increments 'til you can.
*You want about .060" band clearance, Which is very difficult to verify with the trans installed! I developed this procedure specifically for repairing 4L60E's "In Chassis"

Final assembly of the 2-4 Band Apply Servo.....
*Remove the Apply Pin from the 2nd Servo Piston.
*Install the Large Diameter scarf-cut sealing ring onto OD of the 2nd Servo Piston using Trans-Jel as a tacking agent to adhere the seal to the piston.
*Fit the JUST 2nd Piston into the Servo Bore to seat the the sealing ring.
*Fit the small sealing ring to the 2nd piston & slide the Housing over the sealing ring.
*Fit the RED O-ring into the OD groove of the Housing.
*Refit the original sealing ring onto the 4th Piston.
*The Blue O-ring goes on the Servo Cover.
*Hang the Return Spring on the "Knob" at the bottom of the Servo Bore in the case.
*With all sealing rings/O-rings having of liberal coating of Trans-Jel.....Install the Assembly & install the Wire Retainer.

More to follow......

 

[clinebarger]

Originally Posted by JP_Property
Hello Clinebarger. I see you are in Fort Worth. I'm in Arlington. Do you have your own shop here in Fort Worth??


I work for a independent General Repair Garage at the moment & do Transmission rebuilds at home as a side business out of my garage. I'm in the middle of having a shop built & will be opening my own repair facility in @18 months.

I would be happy to take-on the repair of your truck, But I will need TIME as I cannot do it at "work", The Garage I work for has their own "brother in law" deal worked out with a transmission shop. They are not privy to my side business or my plans to open my own full time repair operation.

 

[WyrTwister]

How long does such a repair usually take ?

 

[LeakySeals]

I've had some success with fresh fluid and LG making the 1-2 less stiff. But its still there depending on the day. Seems to appear more on warm days which makes me wonder about ATF viscosity, and maybe the ECU tuning.

I thought the corvette servo made the shift crisper, not smoother?

Is it possible to buy a valve body with all the upgrades mentioned above?

 

[dlundblad]

Is this almost like a jerk? Does it go away when hot?

This is what mine does. When it's cold, I will nurse it until I get to 3rd gear. If I have to get on it, I'll let off the gas from first to second while it shifts. Been doing this for since I bought the truck.

 

[clinebarger]

Next up is to pull the Valve Body, 2nd Accumulator Housing, And Separator Plate......

Valve Body Removal.....
*Remove the filter.
*Remove the Clip retaining the TCC PWM Solenoid with a pocket flat blade, Keep it from flying away!! Remove solenoid. It's the one on the passenger side Front of the valve body.
*Remove the 2 10mm headed bolts holding the TCC Enable Solenoid, Carefully pull it out of the pump Cover.
*Disconnect the rest of the solenoid electrical connectors & Tie the harness out of the way.
*Remove the 13mm headed bolt holding the manual detent spring.
*Remove all the 8mm & 10mm headed Valve Body bolts but 1 right in the middle, Slowly loosen the remaining bolt & allow the excess ATF to drain for a bit.
*Disconnect the Manual Valve Link from the Manual Valve while lowering the valve body.
*Remove Valve Body & sit it somewhere covered up to keep dirt/debris out of it.

2nd Accumulator & Separator Plate.....
*Remove the 3 8mm headed bolts from the Support Plate at the rear of the trans, Remove support plate.
*Remove the 3 10mm headed bolts from the 2nd Accumulator Housing, Remove housing & Separator from trans.

You do not need to remove the 2 bolts with red arrows next to them.
The Yellow highlighted bolts are the LONGEST of the valve body bolts.
The 3 Green highlighted bolts are where the 8mm headed valve body bolts go.
The Red highlighted bolts are the SHORTEST of the valve body bolts.
The rest are the same length.

 

[clinebarger]

Drill your TransGo plate as shown, If you have questions.....ASK before drilling!!!
Yes....The 2nd Clutch feed orifice is very small, 3rd & 4th Clutch feed orifices are large....This is by design!

 

[clinebarger]

2nd Accumulator......

*Remove the old Piston & both springs, You can remove the piston buy tapping the edge of the housing against a flat surface.
*Install the 2 new GM springs in the housing & install the piston just as the old one was with TransJel on the seal.
These Accumulator Spring I recommend here are calibrated for the 093/Vette 2nd Piston by GM!

You will read alot of debate about "Plastic" Accumulator Pistons.....Ignore it!!!

 

[clinebarger]

The 4th Accumulator piston is removed from the case by first removing the Pin from the center of the piston with a pair of pliers, Then remove the piston with the same pliers.

Lube the seal on the new piston with TransJel & reinstall in the case after reinstalling the Pin, The 4th Accumulator Spring will be omitted!!

 

[JP_Property]

Thanks for your input. One more question. Should I worry about or just wait until it craters. Seems like a lot of work to put into a transmission that is 16 plus years old with almost 170k. I assume if you rebuilt the transmission these repairs would be made anyway??

 

[clinebarger]

The Sonnax Boost Valve comes with decent instructions, But here is a couple tips....

*Insert the PR Valve & PR Spring (Larger of the two) into the Pump bore, Hold it with a Flat Blade.
*Insert a long 90° Awl on the back side of the Pump Cover & Into the Window highlighted in the picture. This will hold the PR Valve & Spring in.
*Place the Small Bumper Spring onto the Boost Valve using TransJel as a tacking agent.
*Using TransJel on the O-rings......Install the Boost Valve & push it in 'til the O-rings hold it in the bore by hand/finger.
*Install the Snap ring over the shank of a Flat Blade, It has a FLAT SIDE.....It faces DOWN away from the Boost Sleeve.
*Use the Flat Blade to push the Boost Valve to bottom, Use snap ring pliers in install the Snap ring.
*You may need to use the Flat Blade to seat the Snap ring in it's groove!!

 

[clinebarger]

Originally Posted by JP_Property
Thanks for your input. One more question. Should I worry about or just wait until it craters. Seems like a lot of work to put into a transmission that is 16 plus years old with almost 170k. I assume if you rebuilt the transmission these repairs would be made anyway??



I wouldn't wait 'til it craters, But.....Yes this & even more would be done during a full rebuild.

"Shoring-Up" the hydraulics, Increase clamping force on the Band/Shorten the 1-2 shift, Along with Cleaning-up the 2-3 upshift & 3-2 downshift can extend the life of a sick 4L60E up to 50,000 miles. Your mileage WILL vary!

Paying someone to do "In Chassis" upgrades at such a high mileage is ill-advised......

 

[clinebarger]

Originally Posted by LeakySeals

I thought the corvette servo made the shift crisper, not smoother?


If you simply throw a 'Vette/093" into a trans that's.....
1. Not calibrated for it.
2. Has loose/excessive Band clearance
The 1-2 shift will definitely firm-up....

What I'm outlining is a complete hydraulic re-calibration of the 1-2 shift!