4WD car, do tires squirm on pavement on a turn?


#1

I’m curious: My 2005 Subaru Forester 2.5 X has 4 wheel drive. When I make a turn right or left, in which the front wheels run on a turn radius larger then that of the rear wheels, is there some limited slip between front and rear differentials, or do the tires have to experience squirm?

Thank you

Joe


#2

Google differential. The short answer is there is a mechanism for making sure the tires do not “squirm.” As long as its doing its job, the wheels will rotate at their own individual rates. This very well might be covered in detail in the owners manual as well.

P.s. it has all wheel drive


#3

I will add that in order to preserve the proper functioning of the AWD system, it is essential that you do the following:

Rotate the tires every 5k or every 7.5k miles, in order to equalize tread wear.
If you experience a flat tire, use the temporal spare only until you can safely reach a tire repair facility.
If a damaged tire cannot be safely repaired, be prepared to replace all 4 tires.
(If the remaining 3 tires have more than…let’s say…10k of wear on them, the difference in circumference between those old tires and a new tire can be sufficient to cause damage to the AWD system. The only alternative to buying 4 new tires is to have the one new tire “shaved” in order to match the circumference of the 3 old tires.)

Failure to do what I listed above will result in “tire squirm”, and will also result in expensive repairs. If you are not prepared to do these things, then you should not be driving an AWD vehicle–of any make.


#4

Subarus, and all current 4wd/awd cars, have 3 differentials, one for each axle and one between the front and rear axle, so no tire squirm occurs. The center differential can be of several designs, but all do basically the same thing.

Older designs with ‘part time 4wd’ do not have the center differential, and should only be engaged in slippery conditions.