Need Help With Corvette Servo and Billet 4Th Servo

D68enny · Post by **D68enny** » Mon Nov 27, 2006 7:40 pm

I just installed a corvette servo and a billet 4Th gear servo and a longer pin. Now when I floor it 1st gear holds until redline unless I let off the gas a little then it will shift into second. Then when I am cruising at about 35 and floor it, it does not feel like I am shifting into 1st gear or the highest gear it should be shifting in. It feels like maybe 2nd. I am still accelerating, but not like it should be.

Any ideas on what could cause this? Could the pin tolerance be incorrect. I did not check to see if it had the amount of clearance it should. I just put the stuff back together. I would appreciate any help. Thanks.

Post by **HenryJ** » Mon Nov 27, 2006 7:56 pm

This modification will not change the rpm of the shifts. It will shift faster and will hold the bands with more pressure. The shifts will be quicker and firmer.

The shift points are controlled electronically, as is the kickdown. Those should be unaffected by the changes.

To alter the shift points you will need to use a programmer, or have the computer flashed.

Mine too held shifts way too long, IMO. This was even stock. Adding the servos and pin helped with the speed of the shifts, but I still had the problem of late shifts. That is where the HPPIII was used to lower the shift points.

D68enny · Post by **D68enny** » Mon Nov 27, 2006 8:24 pm

I also have a HPPIII programed in there with the firmest shifts. I am very unfamiliar with how these servos work. I do have firm shifts when just driving normally, but if I step on it from a stand still it will stay in first gear until it redlines and the fuel starts to cut out if I don't let off the gas. My CC shifted fine at the right RPM's before this mod, or at least points I liked. I have read that you can't over do it with the better servos, longer pin , HPIII, and even a bigger reverse boost valve kit (which is not installed), but something is not right. The only thing I did not check was that pin. I figured since it was a new GM part pin the amount of space it needed to travel which is only.125" would be there.

If that pin was to long what would it do to the servos?

20Blazer00 · Post by **20Blazer00** » Mon Nov 27, 2006 9:49 pm

You should back off on the HyperTech shift firmness settings. I have browsed a lot of forums on this subject, and I believe that s-series.org has your answers. There is a "Sticky" on the 4l60 trans and the short of it is. Is that if you install a mechanical shift firming kit then you should not firm the shifts electronically since that will be more than the tranny was designed/programmed for...some even suggest that all you really need is to install the corvette servo with the longer pin. Then when the trans needs rebuilding then you add additional clutch disks to upgrade it to 1/2 ton or full size specification.

F9K9 · Post by **F9K9** » Tue Nov 28, 2006 3:49 am

I don't think Brule was referring to shift firmness with the HPP III. Dropping what speed that each shift is performed at WOT is a nice feature of the programmer.

Post by **HenryJ** » Tue Nov 28, 2006 4:06 am

Does it shift ok under normal driving conditions?

I am running the shift firmness. The added pressure is controversial. There are several that say it is bad. I disagree. The pin should be just fine. The added length reduces lag and holds the band. I really don't know why you are noticing a difference. Perhaps the shift point was too high before? Maybe something did change the affected it? I don't know if something could have been damaged or incorrectly installed and cause you problems. Mine all went in and worked just fine.

This thread has some shift points that others have used - Modifying shift points

What are you running now?

HenryJ wrote:My settings may not work for everyone. The addition of the corvette servo, billet fourth and longer pin do change the way the transmission shifts and holds.
6/10/2006 pm
87 octane tuning , 5600 rpm limiter , 128 mph , 32.75" tires , 1-2 shift -2 , 2-3 shift -8 , 3-4 shift -10 , shift firmness

The first to second shift was about right at 5200 rpm. The second to third shift was too high it almost hit 5500 , so That is why I dropped the MPH on it to get the rpms down closer to 5000.

I would spend some time lowering the shift points. I know that at WOT there are some parameters that change. It will not shift to overdrive at WOT.

You might also want to check out the thread on tuning the throttle position sensor. Adjusting it properly might be of help?

Other mods can affect the way things shift. I know I have had to change mine a few times. Tire size, engine mods, etc.

D68enny · Post by **D68enny** » Tue Nov 28, 2006 3:23 pm

Ok now my problem has changed a little. First gear still holds at real high RPM's even at normal driving take offs. Now it slips into second and the transmission is not locking up all the way. It slips in 2nd, 3rd, and 4th. I put it into first and it is fine. Something has to be wrong with the install. I reprogrammed it back to factory settings with the HyperTech. The only things I did not do that the instructions said were to see if the pin moves back and forth about .125" and I did not put some grease on the big washer just under the big spring and the end of the servo pin. The servo pushes back out when I push it in, so I would assume the spring is in place and working. Looking back I remember putting the servo back together properly, but maybe I am wrong. I will take it apart again as soon as it cools down. The part that sucks is that outer clip on the servo. I cant get it back in by myself. I'll have to see what the wife is doing tonight and try and talk her into holding the pry bar tight to get that clip back in.

D68enny · Post by **D68enny** » Tue Nov 28, 2006 4:42 pm

Ok I am embarrassed to say this but I had the second apply servo in backwards. I usually don't make stupid mistakes like that. People have told me though that your mind will change when you have a child and my kid is two and a half now. He wears the mind out sometimes. I want to thank everybody for all the help. I hope it works now. I have to wait for the wife to get home to hold the servo in and finish it up. I tried to get my boy to help but there is only so much a 2.5 year old can do. He was very excited to crawl under the truck and help out though. That's what counts. Thanks everyone.

F9K9 · Post by **F9K9** » Tue Nov 28, 2006 4:44 pm

Good luck!

killian96ss · Post by **killian96ss** » Tue Nov 28, 2006 5:12 pm

Lot's of confusion here.

There is NOTHING wrong with using the HPPIII shift firmness option with the Corvette 2nd gear servo and 4th gear billet servo.

You DO NOT want to use the shift firmness option if you have installed an aftermarket shift kit.

Changing the shift points with the HPPIII will do NOTHING for part throttle shifts which is where most people spend their time. Changing the shifts points ONLY works for WOT shifts. I have a feeling that people are adjusting their shift points hoping to change how the transmission shifts during normal driving.

How many of you actually floor it every time you take off?

If you do it's really not a good habit to develope.

Steve

Post by **HenryJ** » Tue Nov 28, 2006 7:49 pm

D68enny wrote:... I had the second apply servo in backwards.

Glad you got it figured out!

I was really grasping at air trying to think of something to check.

Good to know what happens if you do that. Thanks for letting us all know

D68enny · Post by **D68enny** » Tue Nov 28, 2006 9:01 pm

I still have problems. Even after turning the 2nd apply servo around I still have 1st gear with a long hold and then after that my transmission just slips in the other gears. I have red on the fine print of the Sonnax 4th gear super servo that it is compatible with original equipment 2nd apply servos, and if you use any other type of 2nd apply servo clearance for the outer diameter of the Sonnax (4th gear servo)steel washer over the full travel of the apply pin must be verified.

This I do not understand. What are they talking about? This is very hard to describe without visual aids. That washer will not travel along the servo pin at all because there is a retaining clip right below it, so it will not travel at all along the pin. I am going to try and find the instructions online for each servo and see if a can get a link to them to make this easier to understand.

D68enny · Post by **D68enny** » Tue Nov 28, 2006 9:26 pm

Here is a link for the Sonnax 4th gear servo. http://www.powerglide.com/parts/parts/77767K.htm

I cannot find the directions online for the Superior Super Servo #k012.

I guess I will call both companies tomorrow and see if the is a compatibility issue with these two parts.

I thought when I found the backward servo i was home free.

Griff · Post by **Griff** » Wed Nov 29, 2006 3:34 am

I'm running a Corvette Servo w/Sonnax Super-Hold 4th Gear Servo and Long Pin and haven't had any problems with shifting.

D68enny · Post by **D68enny** » Wed Nov 29, 2006 2:41 pm

Griff,

Did you have to grind the washer down for the sonnax to fit properly, or is the corvette servo still considered an OEM item?

I think I screwed something up in my transmission. I now have 1st gear and 2nd gear working ok. Firm shits, normal shift points, but when it gets into third it slips unless I have the engine speed the same as the transmission speed the it grabs. I cant give it gas because it then starts to slip again. I must have messed something up. I wish I knew what it was.

This was supposed to be something fun to do to get my mind off of being laid from my job. Then to top that off last night when I thought ok maybe my truck is fixed I was pulling out of the garage and out the driveway and I had saw that some of the Christmas decorations had fallen over into the driveway a bit. I stopped about to get out to fix them, but my curiosity about my truck took over and I said I will just go around them and fix them when I come back. At about that time I feel metal and plastic grinding together. My wife for some reason parked the her van into my lane about a foot more that normal and while I was paying attention to the candy canes laying in the driveway I smacked her car. Was not a good day yesterday./

Post by **HenryJ** » Wed Nov 29, 2006 4:25 pm

It all has to get better

Did you by chance, service the transmission?
I am just wondering if there are any chances that something else could be a problem too.
I know one member who was a little rough reinstalling the pan and damaged some servos. I am pretty sure the same guy pulled the wires on the PCM during the bodylift and had to have the dealer make some repairs there as well.

Just trying to make sure that the servos are the only changes that were made.

D68enny · Post by **D68enny** » Wed Nov 29, 2006 8:15 pm

The servos were the only thing I messed with. I am going to put everything back to stock and see what that does. The last thing I did was put the stock 4th servo back in and kept the super servo in, but had the same results as above. I will go back to all stock and see what happens, but I think the results will be the same. I am stumped as to what I did.

Post by **HenryJ** » Thu Nov 30, 2006 3:52 am

The only thing that sticks in my memory was that spring falling down. I couldn't see up in there, but had to make sure it didn't fall.

HenryJ wrote:Before sliding this all back up into place, check to make sure that the inner spring is still in place and has not fallen down-

Corvette servo

D68enny · Post by **D68enny** » Fri Dec 01, 2006 12:52 pm

I put the sprind on the pin and slipped it on. I have had the servo in out out with different configurations of new and old parts and nothing has changed. I just put everything stock back in and still no go. I was wondering if the servo pin could have been pushed in to far with that one servo being backwards causing it to push the band that drives 3rd and 4th off so the pin is not engaging?

Post by **HenryJ** » Fri Dec 01, 2006 1:00 pm

I don't think you can just put the spring on the pin. It needs to sit properly on the seat in the housing. See how it hangs on that in the picture above.

That may be your problem?

D68enny · Post by **D68enny** » Fri Dec 01, 2006 7:33 pm

I'll give it a shot. I am hoping that that could be it. I feel the spring just sat in the right position, but I would love to be wrong. I will tell you on thing. I am one servo changing mo fo now. I can pull it out re-configure it and put it back in by myself with a prybar and screwdriver in 10 minutes. Great talent to acquire.

Post by **HenryJ** » Fri Dec 01, 2006 7:44 pm

NOT something you really want to get good at

I can't believe you have been able to reuse the o-rings! That is a talent. I ruined at least one every time I disassembled.

D68enny · Post by **D68enny** » Fri Dec 01, 2006 8:52 pm

I tried the spring trick and no luck. Is it just the servo cover O-ring that is supposed to be hard to get out? What about the other O-ring? I was able to get them all out ok the first time I took it apart. If the O-rings look good and feel good do you think they are ok to still use? I am trying to save the new ones for the new parts if I can get this figured out, but in the mean time I have been using the original O-rings on the stock parts. They should be ok. I put a thin layer of grease on top of them to get a good seal. They all feel smooth and same thickness all around. I am trying to hit everybody up on the other sites also to get some suggestions or answers, but not much knowledge in this area.

Post by **HenryJ** » Sat Dec 02, 2006 4:02 am

As long as the o-rings are pliable and intact, you are ok to reuse them.

Do you have a good , local transmission shop? I would ask some questions.

Sorry , I am at a loss as to what happened.

D68enny · Post by **D68enny** » Sat Dec 09, 2006 3:04 pm

Well I figured out what happened and it was not good. I burned up the 3rd and 4th clutch packs. They burn out quick when something is not right. I only drove the truck like 1.5 a miles total from the first servo install to about the tenth time I reinstalled it trying to figure out what was wrong. The damage happened with in the first 1/10 of a mile. My uncle told me clutch packs right away, but I wanted to ignore that and try everything else to see if I could fix it. Deep down I new it was the clutches because of the dark transmission fluid, but I kept telling myself the could not have burnt out that fast.

The total damage was $2300 bucks through GMC, but the good news is my uncle owns a very reputable car repair shop in the area and is always doing favors for the dealers around here, so he asked the GMC shop manager what he could do for him and it ended up costing me $100. Christmas came early. I got the truck back and put the servos in and man that is a great upgrade.

Shifts are nice and firm and to the point. It sort of reminds me of adding a short throw shifter in a manual transmission. The shifts are very quick, no hesitation. I like it a lot.

Post by **HenryJ** » Sat Dec 09, 2006 3:14 pm

That is a real bummer that you had to rebuild the transmission

Good to hear that Santa was good to you this year though.
At least there was a solution to your problem. This time the worst case scenario was the right answer