LS1TAUTO

iTrader: (1)

Car is not tuned yet seems to lock up fine at 40 mph then horrible vibration underneath car almost feels like driveline is vibrating bad, car also feels sluggish in lockup like it's bogging...can a tuner lift the lockup speed a little higher?!?! Cuz it seems like 40 mph is just to low car has 3.23s gears also spoke with stunner that said he will not lockup the tranny?!?!? What's that about?!?!

nj02z

iTrader: (6)

I lock mine up at 55 and that is with 3.89.gears.

FirstYrLS1Z

iTrader: (4)

I have Yank SS3600 with 3.23s'. My lockup occurs at about 40mph. RPM after lockup with virtually no throttle applied puts rpm at about 1100-1200. Doing a very slight throttle increase at that situation without dis-engagement of lock-up does produce a sensation of vibration. You're asking the engine to slightly accelerate while in locked-up non-slip overdrive.More throttle will cause the lock-up to unlock and the 'vibrations' will go away due to the engine being able to operate at a higher rpm due to natural convertor slippage.

gto65lvr

iTrader: (8)

tune the trans lock up points to occur at a slightly higher MPH and retest. If I had my log up I would post where it works great for DD and to eliminate the vibration with the stall converter. Also if its a DD you probably will want to set it so it does not lock up in 3rd to reduce wear on the converter clutch. kinda hard on them in perf. converters going in and out of lock putzing around town.

farmington

iTrader: (14)

always love the posts about problems driving BEFORE a tune. Get the tune first

high n dry

iTrader: (18)

X's 2 on that!

Siciliano15

iTrader: (7)

lol welcome to the well known world of crappy lockup clutches on the yank converters. do yourself a favor, sell that thing on ebay and get yourself a vigilante. had the same issue on mine. yank told me it was my trans. never had a problem on the stock converter. mailed them their converter back so they could look at it and the tracking number said it got rejected by the addresse and was marked "return to sender" well, i never got that thing back and lost out on a lotta money. ended up buying a vigilante converter and guess what? no more problems lol. we are just a couple of many many people with yank converter lockup issues. google it.

mrvedit

The stock 4L60E has a PWM lockup clutch which provides a gradual lockup so that Ms Daisy doesn't doesn't feel a jolt when the lockup engages. Over time the lockup clutch valve gets looser and looser which then lowers the fluid pressure to the clutch. Eventually you get a P1870 code when the PCM detects the lockup clutch slipping.

Many aftermarket converter companies prefer to have the PWM lockup clutch replaced with a on/off clutch so that the fluid pressure is either on or off and not half-on. The Transgo HD2 and Sonnax Performance Pack shift kits do exactly this, as does the Fitzall valve.

I don't know but perhaps the Yank lockup clutch is more sensitive than others to a worn PWM valve.
I have read every 4L60E related post here for several years and do not recall a single other complaint about Yank converters.
I have been very happy with my Yank SS3600 converter, although I recently bought a CircleD 3600 triple-disk just to try something different.

mrvedit

I do think you need to get a tune first and likely raise the lockup speed.
If that doesn't fix it, look into replacing the troublesome PWM lockup valve with something like the Fitzall. This does require dropping the valve body, at which point you might want to install a shift kit.

Siciliano15

iTrader: (7)

youre definitely right about the PWM stuff and a tune could help. in my particular situation even with eliminating PWM in the tune, and altering the governor pressure, tcc duty cycle, and force motor current, those things helped a little bit but didnt cure the problem. i think you may also be on to something that maybe the yank lockups are more sensitive than others. i dont remember if i saw posts on this particular site about it but i know they were on a forum. maybe ls1.com or ls1-lt1 or one of those other sites.