I FINALLY went with a different Torque Converter (pick yerself up off da floor)
For those not knowing me... when it comes to mods, I don't necessarily look for a "percent of change". Instead I start out with a goal, and then do what it takes to reach that goal. And that most of the time I take an unconventional approach. Now that I have covered how weird I am...
An example; when I upgraded to the 3.42 ratio from the 3.15; many will say it's too small a jump (and they are correct in that is is a small change). But I had a goal, and the 3.42's took me exactly where I wanted to be. It didn't matter how far away or how close I was to the goal; I zero'd in on the goal because I knew exactly where I want to end up at.
My 2002 LS1 A4 developed a transmission seal leak, and the rear transaxle would need to be dropped for the repair. I've already done the carrier swap myself, but didn't want to take it all apart again (gettin' old... ) and a trusted Corvette mechanic had recently opened up a local shop. With the car up on his rack, he asked me if I had even considered a higher stall converter... especially since he would be in that area of the car anyways (it would make sense to do the converter upgrade at the same time).
I said no... that I was not interested in a high stall converter. He asked me why, and I gave him "the list":
a. prices of aftermarket stall converters are rediculous.
b. I don't want to add an external cooler (almost mandatory with most aftermarket converters).
c. I don't like the feel of a high stall converter during normal driving.
d. Since I personally will always have run-flat type tires on this car, I didn't want to lose all hopes of usuable traction. I like my Corvette to be a no-brainer to drive.
e. Presently, I could only powerbrake up to 1400rpm; that I would like to increase that.. but no more than a couple hundred RPM increase (because of requirement "c").
I knew this would stop my mechanic dead in his tracks... as I was being too picky, and that there was no way in hell he'd be able to sell me anything.
But he threw me a curve ball; he said there was a GM converter in their truck line that would give me exactly what I just described. He said the STR was slightly higher; the stall speed was a few hundred RPM more, and that it didn't need an external cooler.
I thought he was joking at first; but he had done this about 5 times before for people that were concerned about high stall converters, and that every one of them just loved this TC. We discussed prices and he said if I didn't like it that he would switch back to my original converter at his expense. How could I turn this down ???
Once installed, on the drive home I couldn't notice any difference in the way the car drove with normal driving... ZERO difference. The following day was warm and sunny, so out again for some street testing. From a stop, I could spin the tires a lot easier than before (remember that I'm still running the original factory GY EMT's) and I got a much more meatier chirp with the 1-2 WOT shift. Heck, I even got a little 1-2 chirp during moderate acceleration The car was definitely pulling harder (due to the higher STR).
But today I thought I was noticing a small difference in the normal driving feel. It was so slight that I could of just been imagining it. What I discovered is that the exhaust note during acceleration had changed just slightly enough for me to notice something was different. Keep in mind that the day earlier (when I had the car all shut up due to the cold) the actual "feel" of the car was unchanged.. but this next day my ears were able to detect a difference.
Long story short, there is a slight stall speed change during normal driving.. but soooo slight that only my ears could detect it. Yvonne drove the car yesterday and she said she couldn't notice any difference in normal driving. She questioned if anything had really been done (she wasn't up to doing any spirited driving ).
Then last Thursday I went to the track. My previous best with my 2002 was 12.93 with a 1.96 60'. And this was during super-ideal conditions... (perfect track prep and 60 degree air temps). That was a fluke run, but one that made my day because it was finally under that 13 second mark. Since that run, I have never been able to get into the 12's again ... mainly because of either the heat or poor track conditions. But I could consistently cut 2.00 60' times and 13.0x 1/4 times even during the bad days.
Air temp was 85 degrees, and the track had a lot of rubber pieces laying around. I ran 7 times total. 4 times within 10 minutes ... then I took a break - hoping that the air temp would drop (which it only did to 81 degrees) and ran 3 more times.
I could now powerbrake to 1900 RPM; 2000 if I pumped up the brakes right before staging. Of the 7 runs, I blew the launch twice ... which was interesting because I was never before able to "blow the launch" at the track. Of the 5 runs that the launch went fine, all runs were in the 12's
Here's my best run of the evening:
I truly believe that when another ideal track day comes along, I can get in the low 12.8's or even 12.7
Here's my original list again:
a. prices of aftermarket stall converters are rediculous. the GM part number for this converter is #24208645; you can find it online for around $180
b. I don't want to add an external cooler. With constant highway driving @ 70mph on an 80 degree day, tranny temps never got above 180.
Of my 4 dragstrip runs within 10 minutes, the temp climbed to 199 degrees. I am satisfied that an external cooler is not needed
c. I don't like the feel of a high stall converter during normal driving. could not feel any difference with normal driving
d. Since I personally will always have run-flat type tires on this car, I didn't want to lose all
hopes of usuable traction. I like my Corvette to be a no-brainer to drive. car is still controllable, but just over the edge of being a no-brainer with factory tires. I now can get the tires in full spin mode... but you have to try to do it - by smashing the pedal down at a stop.
e. Presently, I could only powerbrake up to 1400rpm; that I would like to increase that.. but no more than a couple hundred RPM increase (because of requirement "c"). I can now controllably powerbrake to 1900rpm
Am I happy with this new converter... you're damn right I am. Nothing like making a goal, and being able to reach all aspects of it. IMO; this GM #24208645 converter is a good comprimise TC. Serious dragstrip guru's know it doesn't go far enough; but for non dragstrip types... it just may be what you've been looking for.
All credit goes to Dale Clark at TachItUp Motorsports
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This is just the converter I've been looking for! With my 112 lsa baby cam my stock converter is "chopy" coming to a stop. I need a slightly looser unit.
Damn! and the price!
Thanks, Bob
Mike, do you happen know which GM vehicles use this part # ?
I expect someone to come on here (no-doubt asked by an aftermarket TC supplier because of the price) and find a way to bash this discovery. But my mechanic had already done this on C5's for years now... with no problerms. At the track last Thursday, I gave this car holy-hell and everything went perfectly
Again, with my testing... this TC is not a hard-hitting racing type converter. It's simply one notch above factory; and enough of a notch to get a SOTP improvement... and a verifyable difference at the track... with no external cooler needed.
Cool, definitely sounds like a good "old man" TC. Now you need an "old man" cam and some ported heads and and and and
Sounds like you got exactly what you wanted. I'm kinda like you to an extent, I still want my car to be very streetable because well...it's street-driven 95% of the time!
In my old A4 car I went with a Yank3000 (2.0 STR 3000 stall) and I thought that was a pretty good compromise. I probably would have gone as high as 3500 with a higher gearing (had the stock 3.23s at the time - maybe with 3.73s it would have been fine). So, same idea but a little more "extreme". Some people are fine with 4000+ stalls. For me? Forget it.
I just put in a 3000 stall with 342s, and I really don't like the bog/slip when it shifts. It is so far from the factory feel, that I am going to call the installer after the holiday, and ask if it is working correctly. I actually assume that the loose feel is something I have to live with. It was only a $1500 experiment.
I think your way is better. Even a 3000 stall has a trade off from the factory setup.
Good write up. I wish you did it a few weeks ago, I may have gone another route.
I just put in a 3000 stall with 342s, and I really don't like the bog/slip when it shifts. It is so far from the factory feel, that I am going to call the installer after the holiday, and ask if it is working correctly. I actually assume that the loose feel is something I have to live with. It was only a $1500 experiment.
I think your way is better. Even a 3000 stall has a trade off from the factory setup.
Good write up. I wish you did it a few weeks ago, I may have gone another route.
Interesting. I actually preferred the smoothing out of the shifts, especially during normal driving. Of course, under WOT it would shift even heavier so it was the best of both worlds (for me).'
So would you estimate that the difference between stock and this converter would be 500 rpm?
400 to 500.
I could powerbrake the original at 1500 rpm, but I couldn't always hold the car... and it would creep forward and I'd red-light. So later I learned to just go to 1400rpm for a confidence factor.
The new converter is 1800 to 1900 for the same confidence factor.
Hellooooooo high elevens and it would drive perfectly....get better mileage as well.
Great write-up Mike....Converters are everything to a good A4 set-up and represent some of the largest gains at the track without actually doing any engine mods. Sounds like you really nailed your goals and got a nice performance increase at the same time.
Very interesting....
I wonder how this TC would work with my '97 A4 3:42 that has a 224/224 .567.567 LSA114 cam with Patriot heads.
What do you think?
Thanks,
SLPRC5
PS
I also have LT heades, X pipe and Ti exhaust.
Very interesting....
I wonder how this TC would work with my '97 A4 3:42 that has a 224/224 .567.567 LSA114 cam with Patriot heads.
What do you think?
Thanks,
SLPRC5
I have a simular setup w/ LG LTs and would like to know as well!
Location: Marlton. Increasing performance one speeding ticket at a time! NJ
Quote:
Originally Posted by Mike Mercury
that would be a nice upgrade; but I'm done for the year...
Nice upgrade.
Quote:
Originally Posted by DJMRTS
I have a simular setup w/ LG LTs and would like to know as well!
My guess (and I'm far from an expert) is to get the best gains, a higher stall such as 3600 would be best since the cam puts the powerband at a higher RPM.
However, any improvement over stock is welcome!
I FINALLY went with a different Torque Converter (pick yerself up off da floor)
) and a trusted Corvette mechanic had recently opened up a local shop. With the car up on his rack, he asked me if I had even considered a higher stall converter... especially since he would be in that area of the car anyways (it would make sense to do the converter upgrade at the same time).
).
... which was interesting because I was never before able to "blow the launch" at the track. Of the 5 runs that the launch went fine, all runs were in the 12's 
I have a simular setup w/ LG LTs and would like to know as well!
