Installing Corvette Servo

[misterp]

...Mr P has blown his...

This is the 3rd time I've had the transmission out of my truck. First time was my fault, I made a mistake installing the Vette servo and the tranny had to come out to correct the problem; second time was 6-months ago; and now three weeks ago.

 

My advice: the transmission is THE problem component in this truck, and if you plan on keeping the truck for any length of time (like more than 3-4 years IMO) then I highly recommend you spend the money and buy the best damned transmission you can afford from a proven 4L60 builder. The 4L60 transmission is very unforgiving, you've got to have all the right components just so or the thing will not last; and there are only a handful of people I've seen in the last 3 years that have proven they can deliver a 4L60 which can take the punishment especially in the AWD trucks (which are like driving on drag slicks all the time, 100% traction).

 

Factory deficiencies that must be addressed are 3-4 clutch pack failure (which is rampant btw), improved reaction carrier/shell and other hard parts, improved band & clutch materials, correct recipie of shift kit valving & servos... I am confident this time in my own build that I've just about overcome all the gremlins in my 4L60 buildup but it took several tries and admittedly a couple tranny builders as well. At this point my transmission has consumed $5K and 4-months of downtime (in 3 years) and if I had realized that up-front I would have just bought a top of the line 4L60 to begin with from a proven professional that specializes in 4L60 builds since they are so different from other tranny builds; ideas that work in a 4L60 do not work in a TH350/400, C6, Torqueflight, etc and vice-versa, the 4L60 is a 'different animal'. Another thing to consider - even after you have a 'bulletproof' 4L60 expect to have it out of the truck every 2-3 years for new clutches anyways as normal wear & tear; don't think that you will get 100K-miles out of it between rebuilds, that's not realistic for a 4L60 working as hard as these ones have to in order to cope with the weight/power of these trucks.

 

People I've personally judged know what the hell they are doing with a 4L60: Rossler, Chris Kokkonis (CK Performance), Art Carr, Zippy, Toy Shop. People I'm still on the fence about - FLT, PATC. BManSS and I have been learning together on my tranny and I think we've figured out a workable build via experimentation but we've largely gotten our results from BMan's prior experience (himself a tranny builder) combined with in-depth support/knowledge from Chris @ CK Performance. Also for you DFW guys Sprayed99 and his father (a local professional tranny builder) are also very knowledgeable on 4L60s and I understand they have pretty good success with them...

 

RE your question about shift kits installed in the stock trans - the guts of the 4L60 are basically designed to handle about 375 lb-ft of torque; I'm talking the input shaft to the output shaft and everything made of metal in-between. So in real-world terms what this means is that the single most important thing that your tranny must avoid is banging into 2nd, this is critical as you WILL shatter the input drum eventually but OTOH it's gotta grab like hell too. Even after you get the shift behaving correctly you will still have the internal factory deficient 3-4 clutch setup which will glaze over in time because the piston acting on that clutch pack does not bleed down (release) fast enough, in fact it takes almost 10-seconds (!) for that to happen as built by the factory and that is one major factor why the 3-4 clutch pack gets baked; this is just one example of an issue inherent in 4L60s that cannot be solved with *any* shift kit, you gotta tear down the tranny to mod the piston to solve this issue and this is the kind of knowledge only a few tranny builders have ever taken the effort to tackle and solve (considerable effort I might add). So my point is this - a shift kit & servos will help your tranny last longer yes this is true but if you are going to do more than add CAI, catback, and headers to your engine then past history shows you will be deep into the bowels of the tranny in time anyways.

 

About tranny heat - short answer: you want Dex-III ATF to be 165-175 degrees working temperature; synthetic can take a little better temperature spread than that (like 150-180, I prefer 155-degrees). IMO if your ATF is working outside these ranges do whatever you can to get it under control.

 

Technically any transmission modification outside of a routine filter/gasket/ATF change will void warranty, and not only on the tranny but also the axles; likewise any change in torque converter will void warranty on engine short block, tranny, and axles. That said, no GM dealer or tech in the last 4 years has ever been able to discover a shift kit or vette servo install (provided it was done right and the truck does not bang into 2nd) nor has any dealer discovered a TBTC install (it looks factory). A billet 4th servo is easily spied; a more experienced tech will also know if he's driving a truck with a looser converter although they will have to remove the inspection plug to check for a converter swap; likewise the dealer tech would have to disassemble the servo housing or drop the pan to see if a billet 2nd servo was installed or a change was made to the 2nd accumulator.

 

Sorry for the big knowledge dump...

 

When you say "I've blown 2 trannies" exactly what kinds of failures are you seeing? and what parts are in the tranny now? Or were both stock GM units?

 

Mr. P.

[Badkarma]

Great post Mr P, as always. Now Im just worried about my trans, Im gonna start having nightmares lol

[04blacksss]

damn good post much more knoledge about this stuff now.. but the first time i blew my tranny i blew 2nd and 3rd gear to bits. the second time i blew second and did somethin to the clutch. but the good thing is the second time was 100% free due to the free one year warranty on the tranny i blew the first time..

[04blacksss]

i stopped by a local trans shop that has done a few of my buddys trans on their big trucks. i asked how much for vett servos and shift kit and he priced the shift kit at 350 and the servos 2nd and 4th gear installed 400 bucks soo around 800 bucks total... what u think?

[misterp]

i stopped by a local trans shop that has done a few of my buddys trans on their big trucks. i asked how much for vett servos and shift kit and he priced the shift kit at 350 and the servos 2nd and 4th gear installed 400 bucks soo around 800 bucks total... what u think?

You're getting rooked by someone that has no f'n clue what they are doing. You can get all the parts off eBay for $200; the zippy kit is $250-300 (has billet servos). My suggestion is that you get in touch with the Toy Shop; at least you'll be dealing with knowledgeable people and at that rate it'll probably be a lot cheaper too.

 

Mr. P.

[04blacksss]

ya i think ima go there this weekend and see what their price is to do the same,,, so your saying buy the servos and shift kit off e bay and take it to the toy shop or just have the toy shop do every thing encluding buyin the parts from them/

 

 

You're getting rooked by someone that has no f'n clue what they are doing. You can get all the parts off eBay for $200; the zippy kit is $250-300 (has billet servos). My suggestion is that you get in touch with the Toy Shop; at least you'll be dealing with knowledgeable people and at that rate it'll probably be a lot cheaper too.

 

Mr. P.

[rclnc123]

ya i think ima go there this weekend and see what their price is to do the same,,, so your saying buy the servos and shift kit off e bay and take it to the toy shop or just have the toy shop do every thing encluding buyin the parts from them/

 

 

 

Mr. P - good tranny info..

 

you got me wondering. I have a Crew Cab with the 4L60E on a 5.3 supercharged set up.. I have a 9 1/2" 3000 stall T/C ; with 3.73 gear. GVWR of 6850 lbs.

 

Currently running the stock trans cooler. I run Royal Purple in the tranny . My trans temperature averages 180 degrees. Is this too high or about average and Ok. ..was thinking of adding a small pusher fan in the area in front of the s/c intercooler and stock trans cooler.

 

I just recently went through one of the $4500 headache tranny rebuilds and that's because the guy was a well recommended LS7 corvette & drag car trans builder.

 

I'm Living in Houston, Tx. With the current hot weather of 102 degrees. I have the 160 thermostat on the engine.

[04blacksss]

what is 160 thermostat ????

[misterp]

what is 160 thermostat ????

The thermostat is the calibrated mechanical regulator installed in the engine coolant inlet (lower radiator hose attaches to this) and keeps the cooling system's temperature near a desired setpoint temperature; it does this by controlling the flow of water entering the engine. The factory thermostat will keep the engine at a running temperature of 205-degrees, and a cooler thermostat will allow you to tune the PCM of the truck to allow more spark advance.

 

Mr. P.