700R4 Mods & Tips
Install the Billet 2-4 Servo, It has 35% more apply surface as the Corvette servo. And the servo cushion spring is deleted for a harder 1-2 shift.
Put the .500 or .521 TV boost valve in. This is one of the biggest shift modifiers due to higher line pressure bias. More pressure means exact hard shifts without slippage. Less slippage means less wear and hard apply of the clutches and TCC lockup. This will help save the 3‑4 clutches on WOT shifts.
Put the hardened pump rings. These are needed when you start running high pressure from you pump. Use your stock springs in the pump if you are using a Syclone 4L60. They are the strongest available
A Fiber 2-4 band with the anchor pin hole weld reinforced or weld a heavy washer to the anchor hole collar, and drill it out a bit for the pin if needed. Otherwise, the huge 2-4 Servo will rip it by hitting it so hard. Use the fiber 2-4 band if you are using a used reverse clutch drum. Only use a Kevlar band if you what to replace the reverse input clutch drum for a new one. A fiber band will conform to the used drum's grooves where a Kevlar one won't. They both give great apply when they are used properly.
You want Type F fluid for firmer shifts. You will have to change it every 5000-7500 miles though. Trick Shift friction modifiers aren't needed, Trick Shift is Type F dyed blue. Always supplement your fluids with LUBEGUARD. A Few people have had problems with Type F if they haven't rebuilt and used Scotch Brite on the valves to ensure valves are clean and free moving.
Grind the land down on the pressure regulator valve. Two helped, when in 4th gear and the TC unlocks while throttle position starts to drop, the planetary gears get starved for oil. This will increase the flow to the TC lockup clutch for better apply pressure and better flow out of the cooler lines. This willdrop line pressure by about 50 lbs. but the bigger .500 or. 521 TV Boost valves more than compensates for this drop.
Planetaries are weak and expensive to replace, the other reason is that it makes noise sometimes when it passes by the valve. You can modify the sun gears to aid planetary lubrication buy cutting a slit in the gear surface that rides against the Torrington bearing, Cut a small slit in the edge 1/16" deep and then cut another slit 180 degrees (basically straight across on the same surface). Do this mod to both sun gears. If you do this modification, be sure to set your end clearance to .005 - .010." A #72 selective washer usually does the trick. This washer is included in the thrust washer kit. If you don't set end clearance to this range, the torrigton bearing may fail.
The TECKPAK Orifice cup plug reducer on the reverse input piston prevents that hesitance when going into reverse after it has sat for a couple of hours. It's called TC drain back.
If you are bending the tangs on your 3-4 clutch apply ring due to high pressure, get a 3-4 clutch apply ring from a 96 and up 4L60E at your Local GM dealer if you don't already have the better apply ring. It will have a "7" stamped on it. Our trannys should already have them, most don't. This Apply Ring is the strongest available. If you want to make it stronger, TIG weld reinforce the 3-4 clutch apply ring with 1/8" plate steel pieces about 2 V.-" long so they just fit inside the fingers. Drill three holes equidistant in the in the middle down the length. TIG weld at these holes, the greater pressure will cause this ring to balloon out in the middle of the flanges.
Make sure to machine and mic the pump and vanes if they need it for better tolerance and higher pressure. Check to make sure your faces are flat. Check this by using a straight edge and running it over the complete surface of the pump body and the stator body. Flat file it if it isn't flat.
Check the face for flatness. Do the same thing as the pump if it isn't truly flat.
Seal the 3-4 bleed hole on the input drum. They leak too much and it causes the 3-4 clutch pack to bum up sometimes. It's better to just weld, epoxy it shut. I use JB Weld. No more mysterious 3-4 clutch-pack burn‑ups.
Always use the solid Teflon seals on the stator shaft instead of the standard scarf cut seals. '93 4L60's and up should already use them so replace them with the same. The solid seals will hold up to the pressure better and allow for more consistent shift characteristics.
Scotch Brite all servo and accumulator bores.
When you have the reverse clutch drum out, look to see that the area the 2-4 band rides on is shiny and smooth. 400 grit sand paper will help this if needed. Adjust the band to 1/ 16" to 1/8" for the best clearance. Check this by assembling the servo and putting the cover on without the seal at first. Now press in on the cover and check the travel by measuring the clearance between the cover and the snap ring with a feeler gauge. Once you got it correctly pull it out and put on the seals and reassemble.