2004r Servo

Transmission to Rear-end

Moderator: Team

Post Reply
wilson1970
Member
Member
Posts: 82
Joined: Sun May 14, 2017 3:29 pm

2004r Servo

Post by wilson1970 » Thu Jul 12, 2018 6:49 am

Does anyone have any experience with adding a Sonnax Servo on a 1987 monte carlo ss 2004r transmission? Trans works fine now, thinking of adding one to help life down the road.

fastblackracing
Member
Member
Posts: 81
Joined: Sun Feb 15, 2015 12:13 am

Re: 2004r Servo

Post by fastblackracing » Thu Jul 12, 2018 1:37 pm

In GN 200r4 trans yes......years back we used servos out of older 200c trans with
good success. Some of the bigger servos are adjustable from the outside which
helps with the set-up.

I will tell you that the increased apply area from a bigger servo is only part of the
equation here.....The clearances of the band apply pin...the stroke movement if you
will and the 3rd gear clutch pack internal stack up clearance are key to getting the
1-2 and the 2-3 shift firmness and timing of the band release and third gear apply
correct without the free-wheeling effect that can happen when shifting from 2-3.

Second gear hit is largely from the added apply area of the bigger piston.
You may also need to open the 2nd feed restrictons to help feed the bigger servo
and the direct as well.

220-230 max tv line pressure at WOT helps too going down the road....
If you have a true SS trans the factory calibrations are decent but not as good
as the 86-87 GN trans were.....these trans are very sensitive to being messed
with unlike older 350/400 trans.

Amsoil supershift fluid is good in these trans on hi power cars....

CK performance has a good book on these trans with a wealth of info.....I bought
one for reference a few years ago but around 20 years back we went thru 14 trans
build iterations one year to get to where we needed to be with our power level.....
lots of good info on his website plus he is good to buy from.

If you are not careful you can do damage to the 2nd gear band, and or the 3rd
direct clutches easily because the servo also affects 3rd gear apply....when the
2nd gear band turns off you are also applying the 3rd gear clutch pack at the same
time on the 2-3 shift.

I am not a pro builder but can do these trans and worked very closely with my
builder over the years and got somewhat intimate with these things.

[urlhttp://www.ckperformance.com/View/GM-2004R-TECHNICAL-MANUAL][/url]

wilson1970
Member
Member
Posts: 82
Joined: Sun May 14, 2017 3:29 pm

Re: 2004r Servo

Post by wilson1970 » Fri Jul 13, 2018 5:32 am

Ok thanks. This is a stock original 90xxx mile car. Was trying to prolong the life of the trans without the costly rebuild. All is fine so far fluid is good and shifts fine. I haven't stuck the other 450 HP small block with converter in it either as of yet.

lefty o
Guru
Guru
Posts: 1092
Joined: Tue Oct 15, 2013 8:50 am

Re: 2004r Servo

Post by lefty o » Fri Jul 13, 2018 10:30 pm

best thing to do, is not abuse it, keep good fluids in it, and make sure the tv cable is set properly. a good quality 2004r build will take a bunch of power, but stock or normal rebuilder specials, are weak to say the least.

Post Reply