99svtvenom

Have a 98 LS400 with about 80,000 miles on it. When the car is cold it gets harsh shiffting. Even when its completely warmed up it does this sometimes. Transmission fluid is full. Its like it sticks between gears for a fraction of a second too long when shifting causing the revs to go up a tiny bit then engages the gear causing a jolt between shifts. Any ideas? I pray to god this is not the transmission going bad. This car has only 80,000 miles on it and it has already had a replaced starter, and a bad grinding issue with "new brakes"!

PureDrifter

iTrader: (10)

check this first, its a 1st gen problem but is possible.
http://www.lexls.com/tutorials/lighting/bulbout.html

you do realize its supposed to be a little harsh until it warms up right? every 98-00 LS i've ever driven does that when cold, only when you're stomping the pedal and revving the motor before letting it warm up...

atoyot

funny thing is mine sort of does that. Even if it's completely warmed up, i have noticed when i am creeping in say a parking lot, and i'm about to pull into a parking space, some times my transmission feels like it will slam into 1st gear. It only does it every once in a while.

99svtvenom

I know it supposed to do it to an extent when its cold but even when it was at full temp it was doing it every once in awhile. yeah thats what mine does. It feels like it has a shift kit in it when your at lower speeds because it will just grab real quick out of nowhere and cause a jolt. would a fluid change help with this?

PureDrifter

iTrader: (10)

a type-iv change could help if it has the wrong fluid or old fluid in it.

99svtvenom

I will try a fluid change and post an update thread once I get that done. I will let you guys know the difference if any, once completed.

damon

Not sure what the total capacity is but it is around 9 quarts of T-IV.

BTW, Sewell Lexus sold me a case @ $4.15 a quart the other day.
----------------------------------------------------------------------------------
"For each drain and fill process (drain the ATF, refill with 2 quarts, drive around town for at least 5 min to mix the new and old ATF), here’s how much of the old ATF fluid remains (the GS400’s A/T capacity is 9 quarts)":

Percentage Old AT Fluid Remaining after a ATF Drain and Refill Process, and subsequent Drain and Refills
(1) 77.8%
(2) 60.5%
(3) 47.1%
(4) 36.6%
(5) 28.5%
(6) 22.1%
(7) 17.2%
(8) 13.4%
(9) 10.4%
(10) 8.1%

atoyot

i was thinking it was low on fluid, so i checked it. Mine was full and the fluid looked great. i may do a fluid exchange anyways.

MEANDAFAKA

better be safe than sorry

PureDrifter

iTrader: (10)

oh, and the rear trans mount is prolly toasted as well.

atoyot

why do you say that? I only have 48,000 miles on the car. It was owned by a 80 year old couple before me and i have babied the hell out of it.

Are you saying that because of age and the rubber mount dry rotting?

ffcgary1

Yep, jap rubber does not tend to last long due to the nature of the ride that they tried to get, ie super smooth. The rubber also gets a hammering due to the forces placed on it and also the hot/cold weather you guys get.

PureDrifter

iTrader: (10)

rubber deteriorates with both time AND use.

not just one.

atoyot

I understand that.

I really don't think mine is a mount issue. Maybe, but it doesn't feel like it. It's almost as if the shift sensor, cable, whatever it is that controls the shift points is off just a hair. Honestly, i think i'm splitting hairs here so to speak because it's not bad at all. THe low RPM shift only happens once in a while.

I wish i had a garage so i could fool with some of these things. It's getting pretty cold outside, and dark by the time i get home from work, which leaves little to no time to play with wrenches.

atoyot

i have been thinking about this over the weekend.

Does the LS transmission have a torque converter? If so, do you think the torque converter is locking up prematurely?