Corvette Servo Installed

Rolling · April 11, 2009

I dont know why this is just recently something I found out about!!!!!

My truck is a 2007 GMT900 Crewcab with 3.42 gears being pushed by a 'lil 4.8L Kinda doggy when it shifts into second, but holds second forever!

I had my doubts when I first got the 4.8, but after driving it, and putting a CAI and opening up the exhaust, it has plenty of poop to get the truck around, and even moves some pretty heavy trailers without sweating too much. I have confidently towed 5k with it, plus 3 more adults and gear. No probs.

But that lazy second gear shift just nagged and nagged and nagged. Seemed the absolute weak spot, even downhill with a tailwind. At WOT, it just would not shift worth a crap. I looked at timing charts, shift interval charts, shift delay charts, computer control charts, I looked into programmer tunes, I even considered changing the diffs to 3.73s. ( This still might eventually happen...) I thought for the longest time telling the computer to tell the tranny to shift the freaking truck would be the only way to get this pig to keep the little engine that could in the power band through the gears.

then I read about this wonderful little CHEAP tranny swap that would do great things to a 4L60e tranny.

I read everything there was to read here, looked at other sights, watched videos, called local tranny shops and finally decided to do it. It honestly took longer to convince myself to do it than the job actually took. And after everything said and done, all I gotta say is WOW.

Normal light pedal driving attributes are just that..normal. Every once and a while you will feel it 'bump' a little more when it shifts around town. Otherwise it runs and shifts normally.

But when you mash the fun button to the floor... it feels like the trans engages a little crisper than before. Any water on the tires and the traction contol light starts flashing before you get rolling more than a few feet. This would happen before, but now it seems even more exaggerated. Not bad, and its only becoming an issue when I am slamming the throttle at a dead stop when all the snow is melting all over the roads.

1-2 shift at WOT used to lose almost 2500 rpm from the tach, almost completely wasting all the forward momentum the truck gained off the line. Now it is just a quick bump into second, and barely loses 1500. Of course, the stock cluster is probably slow as frozen crap, but according to the tach, it is not losing as much RPM. Which is felt very confidently in the never wrong Butt-Dyno.

2-3 shift was always way up in the band with such tall gears, but when it used to shift again, it had to regain the rpms to continue pulling all the way to Uncle Sams safety device.. 95mph. Now it surges into 3rd at just over 85, and continues to pull hard till it hits the governor.

From a rolling start, the truck will downshift much more positively into the gears, not quite a violent slam but it wastes no time establishing what gear it needs to be in and then pouring the coals to the fire. 60mph steady followed by mashing the pedal results in a 2nd gear down shift which will hold solid till about 86ish with the quickness!!

Never before have I wanted to compliment upgrades with a programmer as I do now. I can't wait to put a few thousand pounds behind the truck now, as I am sure it will perform much more responsively on the highway when I hit the go pedal to pass or just get up to speed.

My kit was purchased locally at one of my trusted tranny shops for less than 20 bucks. I reused the pin and springs, only swapping just the servo pistons. On my GMT900, the assembly was able to be removed from the transmission as an assembly, I broke it down and completely reassembled it on the bench and then put the entire thing back in the trans followed by the cover. If you have the ability to run your (especially 4x4) truck in the air, be prepared for 'service Stabilitrak' and 'service Traction Control' to be displayed, its caused by having the rear wheels off the ground spinning without the fronts matching speed. This will correct it self very quickly when you drive the vehicle and all the wheels spin at the same speed.

If you are contemplating this performance oriented upgrade, DO IT!!!! Its cheap, easy, and nets very noticeable improvements. Lots of guys have been running it problem free for many many miles. If you already have, you know exactly what Im talking about.

After doing this to my truck, I special ordered another 4 kits and have a good number of friends on waiting lists to do this to their trucks.

alaska511 · April 11, 2009

Great info, Jared. Who did you get it from? Do they have them on the shelf?

LAGA · April 11, 2009

I too installed the Vette servo last weekend. I have a 07 VMAX with a Blackbear performance tune. I am really happy with the difference it made in the shifts. There is not a lot of difference at WOT but at slower speeds it makes the shifts faster but not harsh. For under $20 and less than a hour install it is well worth the effort. P.S. If I ever do it again, the install can be done in 20 to 30 minutes. I just took my time since it was the first time doing it.

bigredmariner · April 11, 2009

I did a few weeks back also, and it took me longer to convince myself to do it than it did to do te job. Oregon Performance Transmission had the thing shipped to my door fast, 20 bucks and all the stuff was there. I agree with most everbody that has done this, it's the best $20 I've spent. Installed my exhaust 2 weeks ago, CAI is next once I decide which one to get. Then get the tune.

jvmorgan · April 11, 2009

I installed mine this week and it really firmed up the shift from 1st to 2nd and 2nd to 3rd. I am very proud of it, I was very unhappy how 2nd was holding also. I purchased mine off eBay from Oregon Performance Transmission for $18.00 shipped to my door. The cheapest and one of the most beneficial upgrades to the power train. Easy to install took about 30 minutes to install. Good choice!

Justin

1990ss · April 11, 2009

I too installed the Vette servo last weekend. I have a 07 VMAX with a Blackbear performance tune. I am really happy with the difference it made in the shifts. There is not a lot of difference at WOT but at slower speeds it makes the shifts faster but not harsh. For under $20 and less than a hour install it is well worth the effort. P.S. If I ever do it again, the install can be done in 20 to 30 minutes. I just took my time since it was the first time doing it.

So this can be done to the VMax's 4L70e transmission?

CHEVIN · April 11, 2009

great info cant wait to do mine

nonotme42 · April 11, 2009

Second is barely even holding anymore with mine, and obviously that isn't helped by it being between a 5.3 and nearly 3 tons.

Anyone have a link to a writeup on how to take care of it? I'm hoping its not too late to firm up my shifts, because, damn that 1-2 and 2-3 is HORRIBLE.

I'm not exactly a novice to most of this, but my tool collection has recently taken a serious dive...so does anyone know what a shop would probably charge to throw it in?

LAGA · April 11, 2009

I too installed the Vette servo last weekend. I have a 07 VMAX with a Blackbear performance tune. I am really happy with the difference it made in the shifts. There is not a lot of difference at WOT but at slower speeds it makes the shifts faster but not harsh. For under $20 and less than a hour install it is well worth the effort. P.S. If I ever do it again, the install can be done in 20 to 30 minutes. I just took my time since it was the first time doing it.

So this can be done to the VMax's 4L70e transmission?

That`s what I have.

svensk · April 11, 2009

Second is barely even holding anymore with mine, and obviously that isn't helped by it being between a 5.3 and nearly 3 tons.

Anyone have a link to a writeup on how to take care of it? I'm hoping its not too late to firm up my shifts, because, damn that 1-2 and 2-3 is HORRIBLE.

I'm not exactly a novice to most of this, but my tool collection has recently taken a serious dive...so does anyone know what a shop would probably charge to throw it in?

Get a custom tune done and thy will firm up your shifting. My transmission has 160,000 miles on it and it was slipping quite bit until Justin bumped pressure. It actually will probably extend the life of it for me.

ajswenson · April 11, 2009

I too installed the Vette servo last weekend. I have a 07 VMAX with a Blackbear performance tune. I am really happy with the difference it made in the shifts. There is not a lot of difference at WOT but at slower speeds it makes the shifts faster but not harsh. For under $20 and less than a hour install it is well worth the effort. P.S. If I ever do it again, the install can be done in 20 to 30 minutes. I just took my time since it was the first time doing it.

So this can be done to the VMax's 4L70e transmission?

I put one in mine and it is great!

Rolling · April 11, 2009

Scott, I got the kits from Butch at B&B Transmission on Dimond, right here in Anchorage. Yes, they had them on the shelf. I paid around $15 for the kit with my business discount. Im sure these retail locally for around $20 or so.

alaska511 · April 11, 2009

Scott, I got the kits from Butch at B&B Transmission on Dimond, right here in Anchorage. Yes, they had them on the shelf. I paid around $15 for the kit with my business discount. Im sure these retail locally for around $20 or so.

Cool, thanks Jared.