SPRAYED 01

iTrader: (22)

Im cant figure out if i want to spend the $385 while my converter is at vig getting restalled to get a 3 disc clutch. I would only be getting it to lock it up in 3rd at the track to have a true 1:1 and gain some et and mph.

Who is doing this? Does it require my tuner to be at the track with me in order to figure out the best time to lock it?

School me on this one

Alex.

SPRAYED 01

iTrader: (22)

Come on you crazy auto guys!!!

SPRAYED 01

iTrader: (22)

Okay my tuner said he could do it. He would just need to know what rpm to lock it in in 3rd. Any input on this guys.

XS HP

The best way to figure out the locking point is to overlay two dynos of your car with the converter locked and unlocked. When placed over one another, the hp curves should intersect at a point high in the rpm's. That would be where to lock it, as the locked hp would begin to pull away from the unlocked. Or, at least at the point where hp increases at a higher rate when locked. I ran the time in my sig with the verter locking around 61-6200 rpm. it should be noted that i now run with the converter unlocked at wot as it puts much less of a strain on the tranny. i have yet to run it at the track and see if there are any differences (yank recommended I run it unlocked the whole way-and said I would pick up et)

SPRAYED 01

iTrader: (22)

XS HP,

Thank you for the reply. I now have a plan on how to do this. Curious,did you decide it would be too much stress of the trans because you dont have a 3disc lock up clutch?

ChevyGoldfinger

Sprayed 01,
I've determined that the locking up in 3rd trick is usually only used by tuners on the dyno to get a higher/more consistant HP number out of the car. Ask your tranny builder about doing it at the track, and I will bet he tells you not to do it.
I had a very similar trans/converter/rearend setup in my car not long ago. With the Vig 3800 single disk vert in the car I could make 507rwhp/503rwtq with it locked up in 3rd on the dyno and no problem. However, going with a 150 shot on the same setup, it created a "blow through" condition where the converter with the single disk just could not hold the power. Had to send the converter in and let Jack build me a 3 disk vert and with my race weight he tightened it up as well, (3300/ 3500 area now). Got it back in and no more blow through! Put down the numbers in my sig on a 150 shot. Took it to the track and promptly ate the 3/4 clutch pack in the "race prepped" 4L60E again.
I got pissed off and went with the TH400 conversion.

BTW, I still have my Vig 3 disk that only made it to the 1/8 mile one time. Haven't put it up for sale as yet, but it cost me just what you mentioned to upgrade it from single disk. Has 17 miles on it plus that 1/8 mile. lol I have $1000+ in it, can give you the serial number on it so you can check with Jack about it if you might want it. LMK in a PM if you do.

Just a heads up for you when you go with a bigger turbo, because you are about the same race weight as me and also you are right at the threshold of the HP/TQ numbers that will cause you to be replacing 3/4 clutch packs until you get sick of spending good money after bad.
Good luck.

Circle-D

iTrader: (21)

Locking it up the track is a very interesting topic. First you have to have a converter that can handle the power. Second you have to have the torque curve to overcome the big RPM drop. Third the trans has to be strong enough to hold the extra power. Typical RPM for bringing on Lock up is 6000+ in 3rd. It is a little different for each car. It also depends on how your torque curve is if it will even make you faster. In a NA car it will bring you out of the power band and slow you down. Turbo cars are a little different, they like the extra load and will usually power through it. It really takes some TNT to fine tune it. But like mentioned, you might be pushing the limits of the 60E.

Chris

performabuilt

iTrader: (25)

like circle D says there are some drawbacks to locking he converter at WOT the converter interestingly enough particularly high stalls has a cushion affect in the drive line. lessening the impact on the hard parts particularly the input shaft and drum. However locking it up at the top of third and NOT ALLOWING A 3-4 SHIFT WHILE LOCKED since the converter should not be to far from 1to1 in that state it might not be so bad. However never let a converter be locked during a shift this is asking for disaster to happen.
I have seen stock cars where the TCC solenoid would be stuck on and the car would go into lockup immediately on the 1-2 shift and boom normal driving snap the input shaft in two

jimmyblue

iTrader: (11)

The only good reason, is if you would do the 3-4
upshift before the trap. Otherwise you are ahead
on RWT, leavng it unlocked.

SPRAYED 01

iTrader: (22)

Very interesting.Thanks for all the replies. Im having 2nd thoughts of even spending the $385 on the 3disc upgrade. I was not under the impression it would be alot more stressful on the entire trans to lock it up in 3rd.

12secSS

iTrader: (30)

You actually want to plot the dyno graphs (locked versus unlocked) with the X-Axis displayed as MPH, not RPMs. This is because the TCC is applied based on MPH. I made a post about this (kind of) a while ago, see thread for images and discussion.

https://ls1tech.com/forums/automatic-transmission/828032-b-m-ls1-converter-efficiency-dyno-results.html

koolrayz

iTrader: (26)

+ 1 on the stock PCM using MPH to lockup NOT rpm.
I have done it on and off for years. The advantage is if you are a little under geared on the big end and want to keep the rpm in the powerband. As the others have stated you have to dyno to know your powerband or TNT to see if there is an advantage. Im not much of a dyno fan so I do it at the track.
I always lockup on the street, gives me some extra MPH before I tach out.