C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Torque Converter thoughts?

Old 01-15-2017, 01:53 PM
  #21  
383vett
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Originally Posted by Gibbles
Good to hear, i really liked my 2400rpm stall on my vette, i would say that from the factory i believe the car had a 2000rpm stall.
i dumped the old converter before i found out it's written on the converter, so i never verified.

And i still have not committed to a new converter yet.

does anyone know if a 700r4 can support lockup in 3rd and second?

​​​​​​​If it can support it, i might spend some extra money on a better converter, and install a manual lockup override switch​...
I have been locking my my converter at the strip for decades, both 700r4 and now a 4l60e. I have made over 2000 runs doing this. A few years ago I broke a hardened input shaft of my 4l60e locking the converter up right after the 1-2 shift with my Rossler tranny. I now lock it up after the 2-3 shift and my billet shaft has not broken yet. Full throttle shifts with a locked up converter can take out a weak part of a tranny because there is no "give" during shifts. The drivetrain is locked up and it is tough on clutches and everything else. I have a 5 disk converter that is built for this abuse. For normal street driving, you won't have a problem.
Old 01-15-2017, 02:14 PM
  #22  
Gibbles
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Originally Posted by 383vett
I have been locking my my converter at the strip for decades, both 700r4 and now a 4l60e. I have made over 2000 runs doing this. A few years ago I broke a hardened input shaft of my 4l60e locking the converter up right after the 1-2 shift with my Rossler tranny. I now lock it up after the 2-3 shift and my billet shaft has not broken yet. Full throttle shifts with a locked up converter can take out a weak part of a tranny because there is no "give" during shifts. The drivetrain is locked up and it is tough on clutches and everything else. I have a 5 disk converter that is built for this abuse. For normal street driving, you won't have a problem.
Thanks!

I think it could be entertaining having lockup between gears, i mostly drive the car by manually moving the stick, so I'm thinking an on/off switch mounted to the shifter would let me make best use.

And "normal street driving" as in street tires shifting wot in stop and go traffic?

Last edited by Gibbles; 01-15-2017 at 02:16 PM.
Old 01-15-2017, 03:21 PM
  #23  
383vett
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Originally Posted by Gibbles
Thanks!

I think it could be entertaining having lockup between gears, i mostly drive the car by manually moving the stick, so I'm thinking an on/off switch mounted to the shifter would let me make best use.

And "normal street driving" as in street tires shifting wot in stop and go traffic?
That's right. You won't damage anything unless full throttle with a built motor on slicks. When my car was on the street, I used the lockup as a 5th gear on the freeway. I didn't use it much in 2nd and 3rd.
Old 01-15-2017, 04:17 PM
  #24  
Gibbles
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Originally Posted by 383vett
That's right. You won't damage anything unless full throttle with a built motor on slicks. When my car was on the street, I used the lockup as a 5th gear on the freeway. I didn't use it much in 2nd and 3rd.
Thanks,

I doubt my car will ever make it past 400hp, likely to stay right around 300-350hp.

At least for the next few years...
Old 01-15-2017, 06:46 PM
  #25  
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Originally Posted by Gibbles
I doubt my car will ever make it past 400hp, likely to stay right around 300-350hp.
Transmission durability is one of the few places where crankshaft torque is actually important (as opposed to power). If you have a TPI car that's making even 300rwhp, much less 350rwhp, it will be making prodigious torque. That will stress the t/c and trans as much as higher-winding engine making more power but the same torque at a higher rpm. I don't know how much safety margin there is in these things, so maybe it doesn't matter. OTOH, is it possible to "tune" the speed of the t/c clutch engagement to give a just a bit of slip and reduce the shock?
Old 01-15-2017, 08:49 PM
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Originally Posted by MatthewMiller
Transmission durability is one of the few places where crankshaft torque is actually important (as opposed to power). If you have a TPI car that's making even 300rwhp, much less 350rwhp, it will be making prodigious torque. That will stress the t/c and trans as much as higher-winding engine making more power but the same torque at a higher rpm. I don't know how much safety margin there is in these things, so maybe it doesn't matter. OTOH, is it possible to "tune" the speed of the t/c clutch engagement to give a just a bit of slip and reduce the shock?
The checkball and restrictor in the input shaft soften the converter clutch engagement to a certain extent. They are usually removed for performance applications. A slower converter lockup could fry the paper clutch material faster. It's not really the engagement of the converter clutch that will damage a tranny. It feels just like another gearshift. It is making a gear change with the converter locked up. Since there is no slippage from the converter, wot gearchanges can be hard on tranny components.

Last edited by 383vett; 01-15-2017 at 08:50 PM.
Old 01-15-2017, 10:30 PM
  #27  
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Originally Posted by 383vett
It's not really the engagement of the converter clutch that will damage a tranny. It feels just like another gearshift. It is making a gear change with the converter locked up. Since there is no slippage from the converter, wot gearchanges can be hard on tranny components.
Oh, okay. That makes sense. Thanks for clarifying.
Old 01-16-2017, 01:31 PM
  #28  
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Originally Posted by aklim
Here is my thought. Get a Precision Industries Vigilante. They offer a free restall within 2 years. That means if your pump blows debris into the system and thus the TC, you send it back and they will cut it apart, clean it and if you wanted a restall, so be it. Shipping of course applies. What this means to you is that you can go with their recommendations and if you don't like it, have them restall it after trying it for up to 2 years or if you make a serious mod then.
Originally Posted by 383vett
I've been beating on mine for years and it keeps on ticking; even with full throttle lockups.

Better to pay a little more the first time than to buy something twice.

My vig has been flawless!
Old 01-16-2017, 06:52 PM
  #29  
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Looking over the vigilante, it looks like it's priced inline with the fti srl line.
and looking at one site that has prices listed, a 3 disk lockup is priced at 899.
(probuilt site)
fti srl 3 disk converter runs about 1k

How important is a 3 disk lockup for my hp range?
​​​​

Last edited by Gibbles; 01-16-2017 at 06:53 PM.


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