ibidu1

iTrader: (1)

I IMO believe it comes from worn out front cv axles on the AWD system. Because it only vibrates under throttle load, when you let off the gas the vibrations stop.

MnGs3xx

Its the torque converter in the tranny..... needs a new tranny my has same symptoms and it was diagnosed through Lexus of Maplewood in Minnesota. Highly reputable, the torque converter engages between 20 to 50mph thats when the shutter/shake happens

Steve2424

I think CV axle as well because the wobble is still felt on my car even when coasting -- foot on or off the pedal -- slightly. It's more noticeable in the 20-30/35mph range and then is fine. If I apply more pressure to the gas pedal the shake/shudder is not noticeable when going thru this MPH range.

Why a whole new tranny? I'm sure a reputable transmission shop can source the part and install it. My previous car was an '01 Maxima and the torque converters were notorious at failing on those cars and was something that alone can be replaced. Are the GS's transmissions not designed to have components replaced?

The transmission shifts fine otherwise with only this range of speed being affected if the throttle is applied slightly, but when added pressure is given it shifts fine. For a while I've been hearing a wobble noise and like a "whoom, whoom, whoom" noise when driving. The wobble I can probably cough up to a strut/cv axle, and the latter noise most likely a worn wheel bearing -- symptoms I know all too well from my last car lol. I changed the axles (2x), control arms, struts (3x) and only my driver's side wheel bearing. The symptoms before all those parts failed are what I'm experiencing now with my car when going over rough surfaces and the occasional uneven road surface. If a CV axle is faulty/blown, wouldn't it also affect how precise the shifts are when being transferred to the wheels, as well as the car feeling "planted"?

Side Note: when my mechanic had my car on a lift the transfer unit was audible upon rotation of either of my front wheels which also made the rear wheels spin. Car was not on and all he was doing was turning the front wheels to check for any components that would have an easy tell tale sign of wear. Is this bad? Not audible like "oh my god that's not music to my ears," but like a bat swung and the wind behind it kind of sound.

PS -- My gf's dad has an '08 IS250 AWD with 130K+ miles. The EXACT symptom up for discussion is felt on his car as well in the same EXACT mph range. The suspension on that car you can hear into the cabin when hitting certain road surfaces, yet the tranny shifts fine. It most likely never had fluids replaced aside from oil changes and the other fluids but doubtful on any tranny fluid -- unless their unit isn't a "sealed, lifetime" unit like ours and Lexus has some maintenance schedule for it different from ours.

It's such a PITA because the Lexus dealer near me refused to perform any transmission service with respect to a drain and fill since the unit is sealed, and has a lifetime 100K expectancy according to the service manager who I had take my car in. A statement I expected since a lot of people here mentioned it. Basically no shot at even getting it taken into consideration was the jist I got.

I would love for someone who works for Lexus as a tech, and has worked on these cars specifically to chime in and weigh on the build quality of these cars. I can wish right? lol

Kashill

Issue solved. The transmission shudder (jerking/ hesitation) we have experiencing is due to a faulty operating torque converter, not because the converter is bad, but because the trans fluid is depleted.

GOOGLE how a lock-up torque converter works (the additives in the trans fluid is paramount here). How did I prove this? I took my car to the dealer to flush my transmission immediately after experiencing this issue to rule out the trans fluid but the shudder was still there, however, I did not realized that all the dealer did was to drain and fill (3.8 qrts). I then started down the path of looking for an used low mileage trans until I saw a post from another member about the success he achieved with a trans additive by Lubegaurd. I did a little homework on the additive he used and how transmissions work and figured I did not have much to lose by draining and filling my trans a few more times and give the additive a shot but after the second drain and fill (one by the dealer and one by myself), my shudder was gone completely for over 300 miles and I tried my best to make it shudder with no luck (bad luck for that matter). So for good measure, I went ahead and did a third drain and fill. I'm now going on 200 miles since the third drain/ fill with no issue. I did not include the additive but from my homework, it is a good product and will not hurt if decide to include for good measure.

My car had 130,xxx miles when I bought it and based on the maintenance history, the trans fluid was never changed.

Bottom line, we should be draining and filling our trans at least twice a year until we figure out a way to do a true flush.

storms71

Glad to hear this Kashill! I started this thread a few years ago and your post confirms what I have been telling everyone. A Drain and Fill will make a BIG difference. Unfortuately, the shutter has come back to my car recently, so I had the dealer drain and fill the transmission and Voilà! The shudder is almost non-existent! A word of warning though, be careful about a transmission FLUSH, the service manager at Classic Lexus refuses to do a Flush on a 100,000+ mile transmission and said it would only cause problems and likey kill it. Apparently a Flush will disturb a lot of crud that's lying at the bottom of the transmission, but a drain and fill doesn't do that. So he agreed to drain and fill and it has made such a big difference! No more shudder! I agree Kashill, a drain and fill twice a year will keep the shudder away. Only wish I could do it myself as it cost $180 a pop!