Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum banner

1 - 20 of 34 Posts

·
Registered
2007 gmc envoy_denali
Joined
·
15 Posts
Discussion Starter #1
Just put one in my 07 Sierra Denali and am VERY pleased with the results. Anyone try this on their Envoy Denali? This corvette servo is good for all 700R4's, 4L60E, 4L65E, etc. transmissions...Any clearance issues with the install while the transmission is in the car. I haven't crawled up underneath it to see how much clearance it has in order to swap it out....obviously it won't be worth it, if I had to remove the transmission from the car. In the trucks, there is enough room to do it without removing anything but a heat shield.

I haven't seen very much on this topic in this forum after searching through the transmission modification threads...

Thanks!
 

·
Registered
2002 chevy trailblazer_ls
Joined
·
1,433 Posts
I have one in my Trailblazer (along with Sonnax pinless accumulators and a transgo SK-4L60E kit). I did not have to remove the trans from the vehicle, just lower it a bit to gain some clearance. It was tight, sure, but in vehicle is possible. I was using a lift at my friend's work however so that made it easier than trying it in the driveway.
 

·
Registered
2003 gmc envoy_sle_xl
Joined
·
141 Posts
i just got mines for my envoy but i wont install it until maybe thursday! i dont have a garage so i will be doing it in my backyard,i havent look under my truck yet to check for clearance so i will post when i get it on and will try to video it !the before and after the servo.:thumbsup:
 

·
Registered
2003 gmc envoy_slt
Joined
·
280 Posts
can someone explain what this servo does? also what I would gain by adding it before having my pcm tuned? I keep reading about it but have no clue what it accomplishes.
 

·
Registered
2006 chevy trailblazer_lt
Joined
·
84 Posts
so if a person does this mod and already has a tune that firmed up the shifts to say level 2 through pcmforless.. how does that affect everything as whole? any possible damage from having both done?
 

·
Registered
2006 chevy trailblazer_lt
Joined
·
314 Posts
so if a person does this mod and already has a tune that firmed up the shifts to say level 2 through pcmforless.. how does that affect everything as whole? any possible damage from having both done?
i got level 3 and the servo.... pretty stiff shifts. tolerant... but stiff. youll enjoy it. just hope your not a bumper to bumber traffic driver... or youll hate it! stiff shifts even at 5% throttle.
 

·
Registered
2006 chevy trailblazer_lt
Joined
·
84 Posts
after i posted the question i googled it and found on other truck forums where they had done the same thing and after only 25k miles or so blowing apart the sun burst... honestly i have no idea what that is but they said it involved a rebuild.. think i'll just stick with the tune
 

·
Registered
2002 chevy trailblazer_ls
Joined
·
1,433 Posts
I noticed a bit faster/firmer shift on mine, noticeable but it doesn't feel that much different. The main reason for all the stuff I installed in my trans was to help improve durability and lifespan. Bit quicker shifts and more holding power mean less slippage (and therefore less wear) on shifts.

Vette servo speeds up 1-2 shift and has more holding power.
The Sonnax pinless accumulators replaced the factory plastic accumulators that can crack (though I didn't have that issue in my previous car with a 4L60E which had 161k miles).
the Transgo SK-4L60E kit replaces some springs to again stiffen some of the other shift points for less slippage and less wear. It also replaces the infamous TCC valve that half the 4L60E transmissions have issues with, which results in the torque converter not staying locked at highway speeds causing decreased mpg and increased transmission temp and wear (my old car had that problem which this kit fixed instantly, my Trailblazer did not but I did it as a preventative measure).

From all this, I think the most noticeable thing is 1-2 shift is a bit firmer and the TCC lockup is quicker. Before it would do a slow, smooth lockup which was rather soft (and I'm sure that would cause more wear). After the install, the lockup almost feels like shifting into a 5th gear because it is so quick and precise. But all of it is far from being harsh. I've seen people combine these with a tune shift level 2 without issue (though I don't know if I'd want to as I don't want it too firm/harsh just for driving comfort).
 

·
Registered
2003 gmc envoy_slt
Joined
·
280 Posts
I noticed a bit faster/firmer shift on mine, noticeable but it doesn't feel that much different. The main reason for all the stuff I installed in my trans was to help improve durability and lifespan. Bit quicker shifts and more holding power mean less slippage (and therefore less wear) on shifts.

Vette servo speeds up 1-2 shift and has more holding power.
The Sonnax pinless accumulators replaced the factory plastic accumulators that can crack (though I didn't have that issue in my previous car with a 4L60E which had 161k miles).
the Transgo SK-4L60E kit replaces some springs to again stiffen some of the other shift points for less slippage and less wear. It also replaces the infamous TCC valve that half the 4L60E transmissions have issues with, which results in the torque converter not staying locked at highway speeds causing decreased mpg and increased transmission temp and wear (my old car had that problem which this kit fixed instantly, my Trailblazer did not but I did it as a preventative measure).

From all this, I think the most noticeable thing is 1-2 shift is a bit firmer and the TCC lockup is quicker. Before it would do a slow, smooth lockup which was rather soft (and I'm sure that would cause more wear). After the install, the lockup almost feels like shifting into a 5th gear because it is so quick and precise. But all of it is far from being harsh. I've seen people combine these with a tune shift level 2 without issue (though I don't know if I'd want to as I don't want it too firm/harsh just for driving comfort).
Thanks for the response. So if I put the servo on before getting a tune, what level should I get tune at? Dont think I'd get a 3 like you since Im not really an aggressive driver, rarely go over 2500-3000 range when driving. Im just looking for a better shift 1-2 and if I can accomplish that with the servo mod and improve the durability of the trans. My goal is to have the smoothest ride possible while having the power a tune provides and getting rid of that sloppy throttle response.

:hijacked sorry I did this OP
 

·
Registered
2006 chevy trailblazer_lt
Joined
·
84 Posts
i myself would love to go with the transgo kit... but i am far from comfortable doing it myself. i know i'd create problems from forgetting something.. not to mention the driveway would be zero fun for doing it as well.
 

·
Registered
2002 chevy trailblazer_ls
Joined
·
1,433 Posts
Become buddies with a guy at a shop, that's what I did :D

No actually, we were buds before he got that job. Just was very convenient when he started working there as that gave me access to a lift. He also knows what he's doing so I feel much more comfortable delving into something like that when he's around to help out. I probably wouldn't have done it by myself, especially in a driveway.
 

·
Registered
2002 gmc envoy_slt
Joined
·
3,203 Posts
after i posted the question i googled it and found on other truck forums where they had done the same thing and after only 25k miles or so blowing apart the sun burst... honestly i have no idea what that is but they said it involved a rebuild.. think i'll just stick with the tune
That's because GM used a pretty wimpy sun-shell in the 4L60s, some years are worse than others. Nearly all the shops know to install a HD sunshell during a rebuild, particularly if the trans is for a truck and not an under 3000 lb car. - The built transmissions on-line usually have a HD sunshell and corvette/performance servos in them. The heat caused by slippaging during shifting can harm the trans more often than a failed sunshell.
 

·
Registered
2003 chevy trailblazer_lt
Joined
·
31 Posts
I just got done installing the corvette servo, accumulator pin, hardner spring,and The .490 boost valve. Shifts harder obviously, other then that all seems the same. But it has been literally and hour since the install was completed. If nothing else trans was due a filter!
 

·
Registered
2003 chevy trailblazer_lt_ext
Joined
·
8,770 Posts
What's the difference between the 0.490 and thr 0.500 boost valve? Also, there's a 3-4 servo too, and I think they have kits on ebay that come will all 3 parts (1-2, 3-4 and boost valve). Would that make my trailblazer shift like my housemate's e90? :undecided

 

·
Registered
2002 chevy trailblazer_ls
Joined
·
1,433 Posts
Not sure, I don't recall messing with any boost valve. Unless my Transgo kit came with a replacement... But I'm pretty sure the only valve it came with was a replacement TCC valve.
 

·
Registered
2002 chevy trailblazer_ls
Joined
·
1,433 Posts
You're also talking a lot more money there compared to a vette servo.

By the way, you sure the LS1 fbodies came with these? I know my V6 Camaro didn't (but duh it was a v6), but I was fairly sure there were people upgrading to the Vette servo in their LS1 fbodies. I could be wrong...
 
1 - 20 of 34 Posts
Top