Our headline pretty much tells our story in a nutshell. We began testing on our bone stock 1994 Camaro Z28 automatic on January 27 of this year and it's been a race against time to get our mods completed and drag tested so that we (and our participating manufacturers) don't look like complete idiots. As the weather warms and air density decreases, we've found it increasingly difficult to see an improvement in ET, but we're marching forward and seeing some modest improvements nonetheless.
This latest batch of mods consists of a Precision Industries Vigilante torque converter (2800-rpm stall, retail price: $699), a TransGo shift kit ($109.99, street price) and a complete Hi-Pro trans overhaul by GM overdrive expert Eric Schertz of Countyline Transmission.
Before we jump in, we need to give Eric Schertz a big thanks. GM guys who hang out at Englishtown know Eric is a fixture there with his 9- and 10-second turbo Buicks. He's also a hardcore Impala SS man who knows his overdrive trannys. As a long-time GMHTP fan, Eric has been nagging us for years to build us a Hi-Pro transmission, and we finally took him up on his offer. Boy, are we glad too! As the resident ET junkie at Countyline, Eric has developed a range of performance-oriented overdrive transmissions he calls the Hi-Pro line, which distinguishes them from Countyline's standard mom 'n' pop rebuilds. When we started to see smoke from burning trans fluid, Eric came to the rescue and freshened our 4L60E with a Hi-Pro upgrade. Turns out a bushing on our pump was worn and puking fluid on our exhaust. It looked worse than it was, but we would've been in for a AAA tow before long.
Like we said, Eric works at Countyline Transmission out on "The Island." Over the years he has garnered the reputation of being one of the most respected GM overdrive trans experts in the tri-state area (that's New York, New Jersey and Connecticut for you left coasters). This made him the perfect guy to handle our converter and shift kit install. In fact, Precision Industries and TransGo happen to be some of Eric's favorite vendors for high performance GMs (he says, "Both make my job easier..."), so Eric had absolutely no problem with our choice of converter and shift-improver kit.
Our Vigilante converter, a favorite among hardcore F-body racers, was designed to stall at 2800 rpm. That's a fairly common size due to the fact that computer-controlled 4L60E transmissions in '94 - '95 F-bodies seem unable to shift properly with stall speeds above 2800 rpm (on a hard launch-usually your best-the engine tags the rev limiter in 1st, requiring the driver to lift throttle to shift into 2nd). Nobody we've talked to knows exactly why, but later ('96 - up) F-bodies can get away with more stall with minor (or sometimes zero!) tweaks to the calibration. As a side note, prior to this, we had installed Vigs in both our 1988 Firebird Formula ("Chippin' Away," July 2001) and Jay Heath's '96 Trans Am ("Stall Tactics," Nov. 2000). Like a charm, the Vig knocked five tenths and four tenths, respectively, off each car's ET.
In our research, we found pretty much the entire world recommends a TranGo shift kit along with a Vigilante converter. Even Precision Industries gave the TransGo kit the hearty thumbs up. One of the main reasons they complement each other so well is that any high-stall converter tends to soften gear shifts and the TransGo kit firms them back up. They go together like peanut butter and jelly, especially on a dual-purpose street/strip car.
If you are doing any of this at home, we should mention that the TransGo shift kit comes in two forms, one for the professional rebuilder, and the other (it's a few bucks more) for the DIY guy. The difference is that the "home" version includes a very thorough video tape of the 4L60E installation. Providing you have the right tools and follow along closely, the TransGo shift kit is a piece of cake. With the converter install, it's pretty much a menial labor job of pulling the trans out and swapping converters. The key thing here is to make sure all the splines are engaged in the hub. You'll know it's right if after you bolt the trans back on there is plenty of clearance between the converter hub and the flexplate. You should have to slide the converter towards the flexplate to bolt it up. If you've got an interference fit between the converter and flexplate, you do not have all sets of splines engaged! Lastly, we suggest you leave any trans rebuild to an expert, or risk major carnage. This is not a job for the inexperienced-even with the proper shop manuals. Our suggestion is to give Eric Schertz a call and leave it to him!
After completing the installation at Countyline, we scheduled a day at Englishtown Raceway Park. By this time of year, the weather had kicked up another notch and ambient temperature was now in the high 70s with a stiff headwind. We made a series of runs, all in the 13.60s, with a best ET of 13.606/97.40. This compares favorably to our previous best of 13.761/98.31 which had been accomplished in brisk March air. Our average ET improved by .165 seconds, which is perhaps the most indicative stat of the bunch (see "Track Results" sidebar).
An ET improvement of .165 seconds is off about a quarter second from what we expected, but it's not unreasonable given the track conditions that day. We are not disappointed by this because we anticipate picking up that quarter second in comparable conditions this fall when the air density improves.
Even more importantly, we expect the air density and track conditions to deteriorate more as we push into the summer heat. That will likely impair our track results for our next round of mods too (a pair of Hooker shorty headers, Corsa cat-back exhaust, Dynomax super cat, and MSD wires installed at Classic Restoration in Sloatsburg, N.Y.). But as they say, that's racing.
Another item of note is the drop in trap speed over the quarter-mile. We lost .755 mph in trap speed which equates to a loss of about 8 hp. This is a normal occurrence when stepping up to a high-stall converter such as the Vigilante. Previously, we had lost 1.28 mph from our stock baseline due to a switch from stock radials to ET Streets. Like the converter, this loss of trap speed is normal when changing to a wrinkle-wall slick-type tire from a street radial. Nevertheless, our ET continues to move in the right direction in spite of the fact that TGOW is a full 2 mph slower through the traps.
At the end of the day, the only thing that really matters is ET. And as far as ET goes, the sole contributor to our ET improvement this month is our credible .141-second average improvement in 60-foot time. That's a difference you can feel, and it's not a small one either. We attribute this almost entirely to the Vigilante converter and its class-leading 2.5:1 stall ratio.
That's all we have time for this month. Stay tuned for the January issue where we chuck our factory exhaust front to back for the good stuff and head back to the dyno and the track in quest of even more smog-legal horsepower.
Eric Schertz has been building high-performance overdrive GM transmissions at Countyline Transmission for seven years. In this time, he's learned a lot by building trannies for hundreds of Camaros, Firebirds, Grand Nationals, Corvettes and Impalas. He also owns and drag races several late-model GM cars, including this 1996 Impala SS and a pair of Turbo Buicks (one of them in the 9s with an overdrive 200-4R). We asked Eric some of the most commonly asked questions, and threw in a few we think people should ask.
Q: What is the most important thing for the beginner to remember when installing a new converter in an F-body?
A: Make sure that the converter is installed all the way into the transmission. There are actually three sets of splines that need to be engaged by the converter. If any of these doesn't mate, it will lead to pump failure in a hurry.
Q: Will I need any specialty tools to install the TransGo shift kit at home?
A: The only one an average garage mechanic wouldn't have is the internal snap ring pliers. All of the major tool manufacturers make them, even Sears has an inexpensive pair. You can do the job without them, but it's not worth the trouble.
Q: If I want the TransGo shift kit installed professionally, how much does it cost?
A: At Countyline transmission we get about $375 to install one. That includes the cost of the kit too. If you get our full Hi-Pro trans rebuild for $1,495, that's included there too.
Q: Do you recommend that anything else be done at the same time as the shift kit?
A: Just to change the fluid and filter. Make sure to get a new filter and plenty of fluid ahead of time to make the job easier. This is also a good time to look for any excessive wear or metal in the pan when you pull it down. If there's lots of junk there, the TransGo shift kit won't help. It should really only be installed on a good working trans, so it won't cure any problems.
Q: In a 700-R4 or 4L60E, is it better to shift manually in a drag race or to let the trans shift automatically?
A: In a street/strip application, the trans should be set up to shift automatically in the "overdrive" or "drive" position. When you manually shift it, there's a delay in pressure rise. You push the lever and it won't respond right away because there's not enough line rise. You can burn the trans out shifting manually because there's not enough pressure to hold the clutches.
Q: Do I need a trans cooler on my street car if I have a shift kit or a higher stall converter?
A: I would recommend an auxiliary cooler for any transmission, not just for transmissions with a high stall. The cooler the transmission temperature, the longer the trans will live. Overheating is the worst enemy of the automatic transmission. The Precision Vigilante converter is a very efficient converter so it won't produce any extra heat, but I feel the factory cooling is inadequate to start with for most transmissions.
Why The TransGo Shift Kit Works
To the untrained eye, a shift kit might sound like magic; drill a few holes, swap a valve, put in some different springs and, presto, pick up two tenths or more. Sounds too easy, right? Turns out, there's a strong engineering basis for why TransGo's Shift Kit works so well.
When your automatic transmission shifts, a well-choreographed series of events occurs prior to, during, and immediately after a gear change. These events are carefully designed into the factory shift schedule by GM engineers who have two conflicting design goals: maintaining problem-free operation during and after the warranty period, and to provide smooth, seamless shifts for passenger comfort. As we shall see, from an engineering standpoint, these goals are nearly at loggerheads and give engineers and accountants in GM's service organization real headaches!
In order to provide maximum customer comfort and the least number of complaints from owners, gear engagement during a shift is staggered, meaning for a short time two forward gears of different ratios are engaged simultaneously. A 2-3 shift for instance will slowly release line pressure from the 2nd apply band while the pressure for the 3-4 clutch is slowly engaged. From the cockpit, you feel and hear a gradual slide between gears and your 7-11 slurpee stays put in its cup holder. What your transmission feels is another thing altogether.
As the initial gear slowly releases and the next gear engages, they fight each other and create friction-heat energy. Any time you produce lots of heat energy in a transmission, it's because it was converted from mechanical energy, and that's not good because mechanical energy is what moves your car down the road-and down the track. Slow, sloppy shifts might keep granny's bottle of Geritol from spilling all over the back seat, but it will rob power from your engine like the Lucchese crime family hitting the Lufthansa air cargo terminal at JFK.
The TransGo Shift Kit attenuates or entirely eliminates this overlap between gears-depending on the level of performance increase you want. Under TransGo control, the initial gear releases quickly while the following gear engages quickly. There's less power lost during the shift occurrence and that means lower ET down the track. But wait, there's more. As a side benefit, there will be less friction and heat build-up in your trans which means better life for clutches, steels, bands and fluid.
The down side-if you want to call it that-is that depending on how much performance you want to pick up at the track, you will lose a corresponding degree of comfort in normal driving. We prefer the all-out "three-washer mod" which is the most aggressive setting for the TransGo 4L60E kit. Yeah, it's a little rough around town, but look on the bright side, the wife will never want to borrow your car again!-Johnny Hunkins
|Best All-Stock Run:|
|13.877||99.53||1.988||all stock, radials, Atco, NJ, Jan. 27, 2002|
|Previous Best ET (Round One Mods):|
|13.761||98.31||1.970||March 21, 2002 (SLP mods, ET Streets, Holley airfoil)|
|Previous Average (Round One Mods):|
|13.799||97.97||1.977||average of 4 runs, March 21, 2002|
|Round Two Mods:|
|May 10, 2002, Vigilante converter, TransGo shift kit, Countyline trans rebuild|
|2. 13.606||97.40||1.820||New Best|
|Round Two Average:|