4L60 4L60E 4L65E 4L70E Transmission 2nd Gear Super Hold Servo Kit Sonnax

I had lost second gear entirely, a quick Google search showed to install this kit to try to temporarily repair a stretched band. Straight forward setup and I’ve been running it for months HARD and I’ve got zero complaints. It’s definitely not a forever fix but I’m very glad I’m able to get more life out of the stock 200k mile transmission. I set the clearance up a bit tight so the shift feels super firm. Love it.

Bought this with the Sonnax 4th Gear Super Servo. Install not too bad with proper tools and if you install it in proper order!!!! Follow the instructions, no matter how many transmissions you've done. Once I reinstalled 2nd gear piston in the correct direction, everything went in easily. BUY A OEM SERVO COMPRESSION TOOL. It will make your life MUCH easier. Hardest part was lowering trans enough to get servos in and out. Most time consuming is filing the apply pin. Use a digital caliper, and use a Dremel with the cupped grinding stone. Grind, measure, grind, measure. Had a 2-3flare after I had to replace Super Dupper, made in China wide band. Put a Borg Warner in and had a 2-3 heavy part throttle flare, 100-200 rpm. Also remove first Sonnax 4th Super Servo, because I thought it might have broke band, which was NOT the case. Installed this with new Sonnax 4th, and I am soooooo very happy!!!! 2-3 flare is gone, trans shifts very positively, 4th is holding better also. Makes the car feel like it is getting more power to the ground because of the positive shifts. These two servos should have come from the factory!!! Very, very nice shift feel. Not banging, tire chirping shifts, but firm, push in the back shifts. No lag between shifts, just shifts instantly in next gear.

I ordered this kit with the Sonnax super hold 4th servo and the Sonnax boost valve kit. This was installed in a Caprice wagon with about 80k miles on the transmission. I installed them all at the same time, so I don't know how much of the improvement came from each of these parts. The shift improvement was noticeable to me, but definitely not harsh. My wife did not seem to notice or at least did not complain. So if you're looking for neck snapping shifts from your 4L60, you will need to do more than just these 3 parts.In vehicle installation for this and the 4th super servo was not easy. I had to remove the trans crossmember and lower the transmission as far as it would go. I also pulled the passenger side cat. Clearance was still very tight and this was not an easy install. Installation in a transmission removed from the vehicle would have been pretty simple.

Great upgrade for any 4l60e transmission. Nice firm 2nd shift and more holding power. Sonnax FTW

My older Avalanche runs great but the 1-2 shift was a little slow and soft. I installed this kit in about 30 minutes on my back at home. Granted I have 20 years in the business but it was a simple install. For the novice it could use a set of directions but without them just install the seals in the logical places and swap springs. One note is that the kit doesnt come with the servo cover seal. It is much easier to cut and pull out the seal to remove the cover but without it you cant do that. Order the oring seal and its simple.Trans now shifts perfect. Not race car hard but more like its in Tow Haul mode.

I understand for best performance adjustments may need to be made, however I did expect a part for a GM transmission would be a direct fit as well, there are like 4 billion of these transmissions out there.

very smooth but firm and precise shift i had a 2-3 flare before i installed this now its perfecthad to drop trans down a little to get new longer pin in

Used during 4l60e rebuild along with complete Sonnax Servo performance pack and HD 2-3 valve. It may seem pricey but it seems to have hell of a lot of holding power. Converter lockup now is unreal. No flair during shifts.Shifts are firm and noticeable from 1-2 but the rest are quick with no flair or lag. I’m very pleased with complete package.Items were Installed on 1/2 ton 4x4 suburban.