There's a little confusion here because some of these guys are talking about 2nd gens. Those VB's can be made to auto-lock in 2nd when the switch is flipped at the line. The later 48RE VB's can't be made to do that, so you have to manually lock it up in 2nd.

I've taken back-to-back runs with it unlocked all the way and with it locked up in 2nd. Even with my tight converter it still made a .3 difference by locking up in 2nd. Unlocked = lost power and extra heat.

 

Jrussell, by later you mean 05+?

 

I think all 48RE's are like that, but not 100% sure.

 

mine will not lock in first, anymore...its a 47/48 hybrid

 

48RE valve bodies will lock in first if you put a switch on it. 47RE trannies will lock up in second with the switch. You can make the 47RE valve body lock up in first by doing a little work to it. You can put a 48RE valve body in a 47RE and it'll act like a 48RE.

 

all true, you can put 47RE stuff in a 48RE as well.

 

I guess it depends on how loose the conveter is and how much power you are making. When I had my 97, I'd lock up in 3rd and shift to 4th locked. I tried locking in 2nd, but I only gain 1mph and it wasn't really worth the risk. But when I locked up in 3rd, I had a 1000 rpm drop, sounded really cool, but the poor little single disk DTT converter couldn't handle it for long. I totally smoke the single disk on my 11.86 at 114 pass, so much for unlimited power warranty.

 

Wait, ask some guys, they say and you cannot break the single disc DTT. DTT is the best ?? Right??

 

do you leave yours locked for the entire run? 3 tenths isnt bad at all for just a lockup switch. how hard is it on the trans leaving it locked 2-4

 

Locked in 1st here @17mph

 

HAHAHAHAHA!!!

 

Yep. Locked as soon as it shifts to 2nd and stays locked until I slow down. It's pretty hard on the TC clutches and tranny shafts. I wouldn't think about doing it with stock input/output shafts.

That .3 was with a pretty tight and efficient Goerend TC too. You would notice an even bigger difference with a stock TC...assuming the tranny stays together.