have a 2006 Toyota RAV4 with the following problem: When I back out
of my driveway each morning and place the transmission in drive, a
clunk is heard from the rear of the car. I donít recall hearing
the noise at any other time when driving. Iíve had this looked at
twice, and they were either unable to duplicate the problem or
thought it might be a normal sound. It has four-wheel drive and
around 83,000 miles on the odometer. Any suggestions?
are probably the most difficult thing for me to try to help with.
Lots of folks complain about clunking noises from the steering
column on your vehicle, but noises from the rear are rare. Since the
noise only seems to occur in the morning Iím wondering if the
combination of cold rear differential fluid and elevated idle speed
may be causing a brief jolt in your Active Torque Control coupling
within the rear differential. This is a magnetically applied clutch
pack that blends engine torque between the front and rear wheels.
The clutch plates are immersed in the 90w differential fluid and may
be a little cranky during the first engagement of the day. Limited
slip rear axles can be similarly affected when making sharp turns.
this: If youíre sure of the exact conditions bringing on the
clunk, try selecting the 4X4 button one morning prior to backing out
of the driveway. This should lock the clutch fully, and likely will
change or eliminate the noise, if Iím on track here. Be sure to
immediately release the 4x4 function as soon as youíve moved a few
feet forward, as you donít want to rough up your mechanisms and
tires driving more than a few feet on dry pavement this way. Another
thing to try is to note your cold engine RPM on the tachometer and
try to duplicate this same engine speed (one foot on gas, the other
on brake) as you exit your driveway with the drivetrain at normal
operating temperature. If the clunk is there any time of day, weíll
want to look for other more likely causes.
with a noise like this to have the vehicle inspected by a qualified
technician. Things to check are rear differential mounting bushings,
driveshaft universal joints, axle CV joints, suspension bushings and
shock absorbers, and exhaust tailpipe hangers. If the clunk can be
brought on more readily with careful throttle application this will
really help the tech identify the problem area.
looks OK, Iíd renew the rear differential fluid and add a 3-5
percent mixture of limited slip additive. There are many brands
available. These products are pretty good at mitigating differential
clutch noises, but should be used sparingly to avoid excessive
like to learn more about your Active Torque Control system, hereís
a nice description: