15mph Slip/skip/thump 06 GS300 AWD
 

Getting a thump skip feeling when accelerate to 15mph. Pretty sure it's in the transfer case. Any clues as to what might be happening? Still skips when locked into 1st gear, so it's not the transmission itself.

Also the 4wd wobble everyone complains about disappears after this clunk (come to find out it's the dis-engagement of the front drive portion of the AWD system inside the transfer case at the 15ish mph point so the transfer case doesn't destroy itself when front and rear axle spin ratio is different).

Uh - after reading about common issues with transfer cases I stumbled on tires of different circumferences causing issues. I then went out to my car and saw the idiots at Discount tire put different sized tires front and rear - which I guarantee is the issue. This all started after I got the new tires put on after installing new struts and CV axles... Now I'm wondering if there was any permanent damage done to my transfer case (which I would be holding them responsible for). It is a fairly violent clunk at 15 mph so I wouldn't doubt it caused damage in the past 2000 miles.

FML

Wow that's an impressively stupid mistake. What sizes did they put on?

And you may want to take pictures of the tires mounted to the car so there's evidence that they installed the wrong tires (I'm guessing that the receipt says you bought four tires of the same size, so once the tires are off, it's your word against theirs).

As for damage, the dealership will give you the best diagnosis.

I feel for you. Hopefully the damage is not big.

I took video evidence, and am considering a lawyer (pulled my remote start, detailed it, and was about to sell it with a "bad tranny").

They put 225/ "50" 17 on the rear and 225/ "55" 17 on the front. I didn't even look at them until I read articles of "symptoms of bad transfer case" via Google.

I was just baffled why it would start doing that after front struts, CV axles and tires...

A nice guy at Aamco transmission didn't think there would be much damage after only a few weeks, but to get the tires corrected asap.

BTW this guy's channel is great for detailed workings if you're bored:
https://www.youtube.com/user/WeberAuto

It's not ideal, but if your car isn't flashing an AWD error message it should hopefully be fine. That being said, how did they even end up on those tire sizes? Not only is it not correct to the 225/50/17, the tires aren't even the same rolling diameter. For example on my AWD, I have 225/45/18 on the front, and 225/40/18 on the rear and have no issues. I would suggest a drain and fill of both the front and rear diff and even the transmission (which is possible to do despite being "sealed"). I'm not sure if it would help with the shudder, but i assume it hasn't been done before and wouldn't be a bad idea on a 2006.

Yes - trans drain and fill, front and rear diff fluid change, coolant flush, and pvc oil catch can are next.

Can anyone confirm the AWD transfer case has it's own fluid? The guy at Aamco thought it was separate from the trans fluid, but wasn't sure.

This discussion seems to think trans/transfer case share fluid:
https://www.clublexus.com/forums/gs-...ase-fluid.html


Edit:
225 width is correct, but the '50/55' sidewall height is their error.

I'm fairly positive its connected to transmission, so theres no actual fluid exchange for the transfer case.

Dude you should take it to a dealership for a diagnostic and send the bill to Discount Tire. If they don't find anything, then you have peace of mind. On the other hand, there may be damage or excess wear that isn't readily apparent now, but will turn into a major issue in 20,000 miles. The dealer may be able to find evidence of excessive wear (metal shavings in the fluid, for example) and recommend you get these expensive components changed now, in which case recovering damages from the tire shop should be easy with a decent attorney. On the other hand, if you don't get the problem diagnosed for 20,000 miles, it'll probably be much harder (depending on how much you drive, the statute of limitations may have passed, and their argument that it's just normal wear and tear will be much more convincing).