Many owners of C5's with automatic transmission have no-doubt thought about upgrading their factory torque converter, either when upgrading the rear axle ratio.... of just to help the launch with stock gears.
But, I had previously installed a high stall converter ina 1971 Roadrunner (many... many years ago). Although it was great at the dragstrip... I hated it on the street. Was just too loose for my personal tastes.
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 3.42 rear axle upgrade myself, but didn't want to do that work all over again (gettin' old... ). A trusted Corvette mechanic had recently opened up a local shop. With the car up on his rack looking over the seal leak, 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. aftermarket stall converters are $$$.
b. I don't want to add an external cooler - which is recommended with most higher stall 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.
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 claimed to have performed this swap done this many times before for people that were concerned about high stall converters, and that every one of them just loved this TC.
Once installed, on the drive home I couldn't notice any difference in the way the car drove with normal driving. It was night and somewhat cool; so I took it easy on the drive home.
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 was still running the original factory GY EMT's then) 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 at launch (partly due to the higher STR as well).
But during this drive 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 relaxed normal driving... but soooo slight that only my ears could detect it. My wife drove the car 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 though ).
Then I went to the track... it was a warm day. My previous best with my 2002 was 12.93 with a 1.96 60'.
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:
![Image]()
Here's my original list again:
a. aftermarket stall converters are pricey.
the GM part number for this converter is #24208645; you can find it online for around $180 remanufactured, and about $265 for a new one.
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.
can 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
Hard-core dragstrip guru's will know that this TC doesn't go far enough; but for those like me who's Corvette sees 95% street driving ... it just may be what you've been looking for.
My mechanic was told about this converter by veteran Corvette racer Danny Pop. Here was a note send me by Danny:
GM Astro van convertors work great for your application and a trusted Hydromatic engineer I know turned me onto this along time ago.......Anyone that we have done this for has been very happy with the end result, except one and he chose one of these instead of what he needed ( GM "world challenge" camshaft...way too much camshaft for these TC's ). This works well with any of the 4L60E's or the 700R4's back through the C4's and late C3's. As a matter of fact, I would almost guarantee you that some of the dominate SCCA SS C4 automatic Corvettes of the mid 80's through early 90's were sporting this otherwise "undectable" TC.
It will never "grenade" in your application, I believe that torque convertor was tow-rated to 7500 lbs.
.
But, I had previously installed a high stall converter ina 1971 Roadrunner (many... many years ago). Although it was great at the dragstrip... I hated it on the street. Was just too loose for my personal tastes.
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 3.42 rear axle upgrade myself, but didn't want to do that work all over again (gettin' old... ). A trusted Corvette mechanic had recently opened up a local shop. With the car up on his rack looking over the seal leak, 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. aftermarket stall converters are $$$.
b. I don't want to add an external cooler - which is recommended with most higher stall 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.
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 claimed to have performed this swap done this many times before for people that were concerned about high stall converters, and that every one of them just loved this TC.
Once installed, on the drive home I couldn't notice any difference in the way the car drove with normal driving. It was night and somewhat cool; so I took it easy on the drive home.
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 was still running the original factory GY EMT's then) 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 at launch (partly due to the higher STR as well).
But during this drive 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 relaxed normal driving... but soooo slight that only my ears could detect it. My wife drove the car 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 though ).
Then I went to the track... it was a warm day. My previous best with my 2002 was 12.93 with a 1.96 60'.
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:
Here's my original list again:
a. aftermarket stall converters are pricey.
the GM part number for this converter is #24208645; you can find it online for around $180 remanufactured, and about $265 for a new one.
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.
can 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
Hard-core dragstrip guru's will know that this TC doesn't go far enough; but for those like me who's Corvette sees 95% street driving ... it just may be what you've been looking for.
My mechanic was told about this converter by veteran Corvette racer Danny Pop. Here was a note send me by Danny:
GM Astro van convertors work great for your application and a trusted Hydromatic engineer I know turned me onto this along time ago.......Anyone that we have done this for has been very happy with the end result, except one and he chose one of these instead of what he needed ( GM "world challenge" camshaft...way too much camshaft for these TC's ). This works well with any of the 4L60E's or the 700R4's back through the C4's and late C3's. As a matter of fact, I would almost guarantee you that some of the dominate SCCA SS C4 automatic Corvettes of the mid 80's through early 90's were sporting this otherwise "undectable" TC.
It will never "grenade" in your application, I believe that torque convertor was tow-rated to 7500 lbs.
.
