Alright...
My next mod (well, after I get my tune in a week or so).... what should it be?

I'm looking @ a cold fusion wet kit that some say is pretty good for only $460. I wasn't planning on spending that for a stall, but I guess I might would go ahead and do that now.

Traction is an issue!
I've got stock 255 rubber on there now (though I do have 3.42 rear) and I have some traction problems with my mods below and stock pcm! (Though that may be b/c I've only tried to actually hook and go a few times).

A limited slip or fat tires aren't in the budget quite yet. I'm thinking with the stall I will have to baby the throttle too much to get it to hook, but with the nitrous I'm thinking I could have good traction before I started to spray. And, for further info... I was looking at doing a 75 shot but will probobly do a 100 for when I take it to the track (hey, its adjustable anyway).

Alright, so its kinda between a TCI Street Fighter (they claim 3500-3800 stall speed - and again, traction is an issue) and a 75 or 100 shot wet kit.

Alright - so which should come next considering I want to be able to go fast @ the track and play some on the street, but I want to do it with traction. Tranny longevity (its at 80k) is a "semi-issue" so I would like to know the effect both will have on my tranny with a vette servo, b&m cooler, and upped line pressure.

Which offers better track results?

Sorry for the long post and thanks for any advice!
-Derek

 

i would do the nitrous. with your traction woes you'll probably end up slower. by the gas and have fun.

 

If the point is getting down the dragstrip, go for the nitrous. Intant, but short-lived happiness.

If something that you can enjoy every time you drive your truck is more to your taste, do the converter swap. The converter is going to cost more up front than the nitrous, but I think it would be a lot more fun.

The servo firms up the 1-2 shift. The band in the 4L60-E is not the weak point and making the band engage too hard will shorten the service life of the hard parts and make the driveline sloppy as time goes on.

A higher stall torque converter has both positive and negative effects on the trans.
First the negative - they make heat, lots more than the stock converter. The also put greater stress on the transmission and rear end due to greater torque multiplication at maximum stall.
The nice thing s that you can firm up shifts with a shift kit and the higher-stall converter will soften the blow. Basically, the higher stall speed will dampen the jolts of the clutches and band engaging faster.

Getting firmer shifts from line pressure increase with a 60 is not good practice. It robs the lube circuits of fluid and creates excessive wear on the trust washers. It's not the WOT pressure that matters as much as prolonged higher pressure at cruising throttle. Better to get the desired firmness from a shift kit or the combination of a shift kit and exotic band and 3-4 clutch pack.

 

What if I had the tuner jsut barely increase the line pressure at part throttle (where I'm at 99.9999% of the time) and just have him really go to town with the WOT line pressure?

James B - do you think traction would be an issure for me or not if I go with the stall?

Thanks for the info - keep it coming please!

 

I have all what you have mentioned (Eaton LSD, TCI 3000, NX wet)and I will tell you without a limited slip... forget about a stall and nitrous.

If you are considering nitrous, I would HIGHLY recommend nitrous express. Nitro-Dave is a great sponsor and he can help you out with choosing the kit and all the accessories. NX comes with a lifetime warranty and you can't beat that. I have a friend locally who has the cold fusion kit and has had several problems. I would stick with a bigger name such as NX. I bought my used kit for 300 bucks.

Stall converters. I have the tci-3000 and its a great street/strip stall. You will barley notice that its an aftermarket stall until you nail it... then you will be painting black stripes behind you.

If you plan on eventually spray and use a stall, choose somthing that isn't too radical. I think the 3000 2.2 str is perfect because nitrous makes alot of torque and wraps up those RPMs fast. Using a mild stall like a tci3000 will let the nitrous work its magic through most of the powerband.

But even with my eaton posi, and the tci 3000 stall.. from a dead stop I will fry the tires. One time I tried hitting the nitrous outta the hole on a 125shot, my 3000 stall, 4.10 gears, and street tires. My speedo was instantly at 40mph and I let off cause it reved so damn fast I didnt want to hit the limiter.

 

Wow!
How much did you pay for your tci 3000 and where did you get it?

The only tci verters that I've seen are on summit... and one is a 2400 "breakaway" and the other is a 3500 "street fighter."

And are you sure I can't just wait till like 20 to spray and hopefully grab traction?

What problems did the guy have with that nitrous kit?

Thanks,
Derek

 

That's really a compromise. The most critical shifts are the 2-3 upshift and 3-2 downshift. Both of these are double-event shifts. Raising the line pressure doesn't have the effect a shift kit does on these shifts. It's a little hard to explain, but basically, during the 2-3 shift the band has to let go and the 3-4 clutch has to engage. If the 3-4 clutches engage too soon it will bog for a moment because you'll experience a little bit of fourth gear between 2 and 3. If the 3-4 clutches engage too late you'll feel a little bit of first gear between 2 and 3. The whole process gets more complicated when the downshift timing must also be considered. Shift kits change the accumulator springs and recalibrate the feed holes in the separator plate. Certain valves are swapped out too (boost valve most importantly, which handles line pressure) for a BALANCED upgrade. All these recalibrations work together to keep all these shift events timed right. Line pressure adjustments are no substitute for a true shift kit.

Well yeahhhhh... of course traction will be an issue with an open differential!

Even WITH a Posi AND the phattest tires you can fit under there, traction will always be a lingering problem if you've got the torque. Case in point : http://james.jaguar.net/pics/launch4.mpg

 

I paid like $454 from summit for the converter. If you are doing a converter, get a transgo, servos, and cooler while your there. Everything said and done will be about 1 grand.

I am sure that if you hit your nitrous in 1st gear (street tires) you will burn your tire(s). Before my stall converter, I'd launch and at about 3000 RPMs hit the spray, and I would just fry the tires. And at 3000 rpms in 1st gear, Im around 20-23mph. So yea.....

My friend had problems with the jetting with that kit. He had many different answers as to what jets to use, etc. They are suppose to be based off the NOS super powershot noids. They are pretty small, especially compared to the NX. He eventually connected a NX shark nozzle and used NX's jets. Works alot better now.

 

[QUOTE=James B.]

The servo firms up the 1-2 shift. The band in the 4L60-E is not the weak point and making the band engage too hard will shorten the service life of the hard parts and make the driveline sloppy as time goes on.
QUOTE]

How does this make the driveline sloppy?
I have a 99 ECSB with 75k miles. Its dropped 4/6 and I am installing a carrier bearing bracket thursday because of driveline vibration. I never thought of something inside my tranny being the problem......

 

There are a lot of close-tollerance mechanical junctions in the driveline. In the torque converter there are splines between the turbine and input shaft and between the stator and stator shaft. In the transmission every steel clutch plate is splined to its drum and every friction plate is splined to its hub. In "drive" the forward clutch pack is engaged all the time and the 3-4 clutch pack is engaged in third gear and overdrive. There are two planetary sets, each with four (4L60E) or five (4L65E) planet gears, each with a sun gear splined to a shaft. From the transmission you have the Slipyoke splined to the output shaft. The yoke has u-joint, each with needle bearings. If the truck has a transfer case add all those mechanical junctions. If the truck has a two piece driveshaft there is a slipyoke and splines there with another U-joint. At the rear end it goes through another u-joint to the pinion shaft. The pinion yoke is splined to the pinion shaft. Then there is the pinion to ring gear lash. inside the differential there is tollerance between the spider gears and their shaft, and lash between the spider gears and axle gears which are splined to the axle.

The point is, there are dozens of places where torque moves from one part to the next connected only by the tollerances between the parts. Setting up the shifts too firm is like turning the driveshaft with an impact gun. Inside the trans you have aluminum clutch hubs and drums splined to steel clutch packs. These aluminum parts do not handle instantaneous torque spikes such as those experienced during jolting shifts. Secondarily, jolting shifts also affect your belt tensioner's life, motor and trans mounts, suspension bushings, and belt life. With violent upshifts the motor drops RPM so rapidly that the accessories overrun the crank with great force. If you could watch the serpentine belt during a jolting upshift you would see the tensioner bottom out to its maxed position and the belt ride up in the groove of each pulley. the accessories will slip on the belt as they overspin it.

The more thrashing the driveline takes the more quickly all these tollerances between parts will losen up and get sloppy. The rear differential and axle splines are the first to suffer since the pinion and ring gear are multiplying the torque from the driveshaft by a factor of the gear ratio.

I don't like alot of play in the driveline. The best way to keep it that way without sacraficing the way you want to drive is setting up the WOT shifts to be civilized and not jolting.

The band in the 60 is wrapped around the reverse input drum. It is engaged by a pin with two pistons, one for second gear and one for fourth (OD) gear. Installing the "Corvette Servo" affects only second gear since fourth is handled by a different piston. Bands are semi-self-energizing. Trying to engage them too quickly will result in violent grabbing and a jolting shift. Some people are amused by the tire barking this causes during the shift, only because they don't understand what an absolute hell this is on the parts. This limitation is one of the factors that holds down any trans that uses bands to shift from smoothly scaling up to higher power-handling. (Incidently, TH400 and 4L80-E transmissions do not shift with bands, they use all clutch packs. Bands in those units are used only for manual overrun or reverse.)

I will always cast my vote for a smooth but firmly shifting trans calibration over a solid jolting setup. Everything will simply last longer and provide a better ride.