Ok, I'll admit I don't know jack **** about automatic transmissions. For my dad's bday coming up I'd like to order him a servo upgrade for his truck and install it for him. His truck is an 01 silverado 4x4 if that makes a difference. I want to know who makes the highest quality servo upgrade since they're all fairly cheap. I'm just hoping the servo upgrade increases the pressure enough to stop the little bit of slippage he's getting under WOT during the 1-2 shift only. Any info as to what brand servo to buy and where to get it would be great. TIA.

 

i got a transgo corvette servo from oregon peformance tranny for like 20 bucks and it definatly helped the 1-2 shift

 

look at 4l60-e.com

 

PM Zippy, he can sell you what you need.

Shift technologies makes good servos.

 

Do certain servo's grab harder than other servo's?

 

GM corvette servo is what i run... Do that in conjunction with upping the tranny shift pressure (2-4%) and lowering the shift times... Are the tranny pressures stock, if so i bet raising them a little bit will help...

 

I always use the Corvette unit from GM, if you go with a harsher one, it can break the band in the transmission (snaps the ear off where it catches the servo piston). Also, while you're in there swap out the 1-2 accumulator piston from the OEM plastic **** to a metal one (I use a Sonnax).

FWIW: All my GMC has with a 2600 stall is a Vette servo, upgraded acc. piston, and the shift points/line pressure done via EFIlive and it has stood the test of my right foot for 4 years with 0% torque management. No cooler, no shift kit, never even cracked the case open.

 

From the sounds of it, when in doubt use GM. I'll use a genuine GM corvette servo then. Corey, I've done all the tuning on the truck and it runs out hard BUT I was too afraid to mess with shift pressures (not knowing how high to go) or lowering any of the shift times. Do I do anything to the force motor current? Right now my dads tranny settings are stock, I just did engine tuning for the time being. How high can I increase shift pressures safely on a stock trans (I would scale the table by a percentage) without the servo upgrade? Otherwise what's the max with the servo upgrade?

 

Set the line pressure to the factory tow/haul settings. GM already did all the work in identifying the optimal shift pressures. Reduce the shift times to .300 across the board.

 

Use the base pressure tables (1-2, 2-3, or 3-4), raise it by small precentages, like 2% at a time, go drive and repeat if necessary... Log Delivered Engine torque to know which cell your in... Also log the same for the desired shift times... Supposedly 0.3 is a pretty good value to shoot towards...


Start with lowering the shift times, then start raising the pressures a couple % and see if it helps the slippage.