Lvangundy

About 3 days after I had the 3.76 gears installed my car has been lagging or not shifting into 5th gear. I'll accelerate from a stop and the car stays in 4th gear indefinetly (one time up to 70mph) until I manually put the gear shifter into 4th and back into 5th.

This doens't happen every time, so I'm not sure what's going on. Anyone else experience that?

rominl

iTrader: (4)

lee, you mean even with the rpm up to 4000 it still doesn't shift in to 5th?

FutureGS400

Not that I'm aware of! Sounds like you have a trans. problem or maybe a lock up clutch problem with the TC?
Don't know why the gear swap would cause this unless it's just coincidental. My trans shifts just fine. I assume you have not gotten any CE lights?

Lvangundy

I'll try to repeat the process again today, it definetly wasn't up-shifting properly.

I'm going to do a trans fluid drain/refill soon, but I don't think that will solve this. It seems like the computer is weirding out trying to figure out when to shift. 3 days seems like ample time for the comptuer to learn so it makes sense.

TeeLex

iTrader: (24)

I've had no problem with my car after the Torsen 3.76 LSD install either. The differential really should not have any effect on the transmission. As stated by FutureGS it may just be coincidental.

FutureGS400

Good idea-start with the easy and/or less expensive fixes first! Some have reported better shifting with a good synthetic e.g. Amsoil, Redline, Royal Purple etc. but it sounds like your problem is a bit more substantial.
Between your "slow" acceleration runs, and the trans problem it sure sounds like something unusual going on! Sorry can't be of more help....

rheiy

I've had my 3.76 for about 9 months now and just recently, I noticed that the shift from 4th to 5th is delayed sometimes. Or shall I say, it feels like the car is holding 4th gear longer when it should go to 5th. It only happens when the car is fully warmed up and it does not happen all the time. However, I don't have any lag in engine performance. Under wot, shifts from 1st to 2nd, to 3rd are perfect. (I have not tried any wot from 1st through 5th for obvious reasons of not wanting to get a ticket for doing 100+mph) Overall, I'm not sure if I should be concerned about the occasional 4th to 5th shift delay

bitkahuna

iTrader: (20)

Mine does the exact same thing occasionally. I can't imagine it's a real problem. I wasn't sure if it was the diff or maybe the precision torque convertor leaving the tranny occasionally a bit slow.

SoCalSC4

I'll look into this. I was talking to Ted at Dynamic Auto Service (Master Lexus Tech) about TCs and he told me not all of them have the ability to lock-up and won't go into overdrive.

Apparently, this is why the 430s throw a check engine light with TCs installed- the ECU is looking for the RPM to drop in overdrive, but they don't lock-up in OD and the ECU calls a foul.

chuckb

does Lvangundy have an aftermarket TC?

Lvangundy

no, stock.

the shift delay is rare, and doens't seem to be affecting anything, but it would be good to note this for other people who might get the 3.76 w/LSD.

chuckb

I wonder if this is a 430 thing only?

JBrady

Ryan, this is a SERIOUS as well as DANGEROUS PROBLEM...

There is NO time to loose. You are in mortal danger. You MUST remove the LSD immediately and ship it to a SAFE location to avoid catastrophe.

I will PM you my shipping address...

Lvangundy

Who's Ryan?

You had me there for a second.

bitkahuna

iTrader: (20)

As I said, it happens on mine once in a while (a GS400 with upgraded TC and 3.76 rear end)