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Reverse Gear Thump

2901 Views 3 Replies 3 Participants Last post by  blancofire
My IS-F has always made a "thump" when selecting reverse gear. This is particularly true when the engine and transmission have just be started cold.

We've just bought a new home with a steep drive down into the garage. When I reverse out in the morning everything is smooth and uneventful unless I pause on the incline. When I select reverse again there 's a loud thump ... or thunk ... at the same time the doors lock.

Most interesting, I notice the event is louder the higher the rear of the car is above the front.

Could this be the differential? I did change out the factory oil for Mobil1 75W-90 LS at 10,000 miles.

Year: 2008
Miles: 21500
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Surprise: It's Normal

I booked the IS-F in to the dealer and surprise, surprise ... the behavior is NORMAL!

Although the steepest grade at the dealership was about half that of my driveway, the car dutifully thunked its way into R from P. This occurs if the emergency/foot brake is NOT engaged and the car has rolled forward onto the transmission parking pin.

The service manager tried it on other vehicles and more surprises ... every Lexus did it! He even tried a LS ... same engine and transmission in many ways ... and it thunked too.

Most amazing to me, the Toyota Camry loaner I was given also thunked!

Try it on your IS-Fs but be warned: the steeper the grade, the more alarming the resulting thunk.
I do not have too much of knowledge but it could also be the clutch plate.. maybe..
I live in florida which has 0 inclines but I do notice the "thunk" every once in a while, but need not worry!
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