That is my question. I've recently changed to a Trak cam and 4:10 gears. My present t/c stalls way below my peak tq numbers and is a dog off the line using slicks. I've talked to mfg of my present t/c and they said that since I drive minimal street and race at the track occasionally that I should go with a 4000-4400 non-lockup t/c in my 4l60e. Less rotating mass and will save me around $300. I need to hear some opinions from you guys.

 

I wouldn't go with a non-lockup just because when you do drive it on the street, it might get a little annoying, not to mention they're not easy on the fuel economy... But if you rarely drive it on the street, then go for it.

 

i'd go lockup. you're pretty much damning the car to the track with no lockup. it's nice to be able to go out and cruise without beating the **** out of the engine, tranny and your wallet from the high rpm cruising.

lockup like you need it to breathe!

 

When you say "limited street" driving, are we talking in town or on the highway? You're rarely locked up during city driving, so you wouldn't be hurting at all there. You for sure won't want to drive a non-lockup converter that big on the highway though. If you can keep it on city streets and the track, I say no lock-up. Any highway driving at all and you'll wish you had it.

 

I do drive some highway now with my 3500. When it locks up the rpm only drop 200-300 rpm. That isn't so bad is it. Also these things don't lock up at WOT anyways do they?

 

You are correct, the converter doesn't lock at WOT. With a 3500 stall, I'd think you should be dropping more than 200-300 rpm when the converter locks unless you've barely got your foot on the gas. My 3600 stall drops from ~3000rpm under light acceleration at 70mph to 2200rpm when it locks.

 

It isn't just the RPM with regards to mileage, but the stress on the transmission. I spend a good portion of my city driving locked up and i'm sure it helps keep the tranny temps down.

 

+1

If they are only dropping 200-300, something is wrong with your shift points or TCC lockup settings. Swing by and I'll look at the tables. I got mine dialed in nicely. It just takes time and a bit of tweaking to get it where you will like it.

 

I decided to make my car a limited street car and now mostly use it for track but I still drive it there and I have a 4000 converter and I think lock up is a must this converter its real loose and im sure it heats the tranny up like crazy I actually usually drive in the city in 3rd gear so the converter locks around 30 mph this way it saves trans heat by being locked up. So I would prob get a lockup converter.