Hey guys. Once again my car is back at the dealership. This time it is for the center diff. There was a rattling noise coming from the rear when turning the car or making a u-turn. Now I'm being told the center diff is going bad. Background: The rear diff was replaced because one of the rear tires which i replaced had a greater circumference of an inch compared to the other side. The tire was on the car for less than 300 miles. This caused a whining noise in the rear diff, so i replaced it with a brand new one from subaru. My question is would the tire i had that caused the rear diff to go make the center diff to go as well? Would the center diff only show problems after the rear one is replaced? I'm trying to understand how the center diff would be affected so badly by the tire. since subaru did an inspection on the diffs, shouldn't they have disclaimed the first time that the center diff might possibly be failing due to the tire? Never did anyone say anything about the center diff. I was told the center diff was fine, and then after getting the rear one replaced the center one is all of a sudden showing problems? It doesn't make any sense. Any ideas guys?
I am sure that they will blame it on the tires.Customer pay is were they make their $$.warranty usu. pays squat for repairs.It would seem funny that a diff tire diameter would destroy both diffs in less then 300 miles. did you have a completely wrong size??or just a worn or dif. brand.?
That really stinks but doesn't surprise me at all. In my experience it sounds like a pretty reasonable occurence, I don't believe you're being jerked around by the dealer. Many cars w/AWD or LSD are VERY sensitive to tire circumference differences and the damage to the center diff just wasn't apparent at the time of the diff swap.
Of course they are going to blame it on the tires when the damn tires are at fault! I don't think they're trying to rip him off, I think that it was just plain and simple the off-size (by an INCH apparently which is a hell of a lot) tire that f'd everything up. Nothing weird there. PS: tin foil hats went out of fashion a while back
Good god never what have thought a slight difference in circumference would cause such a big problem. An inch is one thing but I think we have another member that was FAR less. Looks like I am headed outside with the cloth tape measure to make sure I do not have one really worn tire.
the tire was the the same size as the rest, but the brand was different (falken). I learned with my last post on the rear diff that even though they were the same size that different manufacturers vary tire size. I know the tire probably is the cause, but i just wanted second opinions. I don't wanna get jerked around if i don't have to.
If you did put a off sized tire on there it would affect both the center and the rear diff's. Just compare it to being towed from the front two wheels that would fuck all diff's up. But what i would do is look at the diff plates. That would tell you if it was abuse or defect. Personaly i dont think that 300 miles would cause it to go bad. I know plenty of people that done worse and had no problem.
He did not use different size tires... just different brand which seems pretty weird to have 1 inch difference... Good luck with everything Dusty.
well guys yes the different tire manufactors sizes are a little off but a 245/45r17 with the same profile is not going to be that much different. if it was then they will have to be completly different tires sizes. also your car has abs, which monitors wheel speed that will activate abs when needed. so if the tire size was that far off to destroy diffs then that means all the wheels are moving at different speed( smaller wheel rotates faster than a larger wheel etc...) and the abs light should have came on at some point, either while accelerating, stopping, or even maintaining the same speed for a long time.
If one goes out...doesn't that mean the other may be failing??? And different brands may have different diameters. Dusty...sorry to hear your having this problem and I hope its the last!
In order to be off by an inch circumference, it just needs to be off by an inch / pi diameter wise. That's less than 1/3 of an inch. Let's do some fun math. A 245 tire is 245/25.4 inches wide. Roughly 9.646 inches. 45 profile = sidewall height is 45% of width. 9.646 * .45 = 4.341 Multiply times two, add in a 17 inch rim: 4.341*2+17 = Oh, around 25.68" Now let's switch to a 40 profile tire. 9.646 * .40 = 3.858 3.838 * 2 + 17 = ~24.72" So between a 40 and a 45 profile you have almost a full inch DIAMETER difference. And you're telling me 1/3" worth of slack BETWEEN TWO DIFFERENT BRANDS--this more clear now??--(meaning both could be off by as little as 1/6") isn't likely or possible? The more you know!
ok guys, its not that he had different sized tires as in a 40 or 45 series sidewall. they were all the same 225/40r17. the thing is that he had a blow out on the right rear and went to some aftermarket shop and they put a brand new falken tire on and he still had his original factory reo70's with like 17,000 miles on them. and we all know that reo70's treadwear doesnt last that long. so with the brand new tire and the 17,000 mile original tires there was about 1 inch differance in circumferance. and yes this information is in your owners manual. you must use the same size tire, same manufacturer, and same tread pattern. and the tires have to all be within 1/4 of an inch in circumferance or else you can have problems. also it depends on how hard you drive your car on how soon you will notice problems. also pulling your e-brake around turns (drifting) will fry your center diff too.
FFS, I just went through explaining this a post above yours. I illustrated that with the difference between a 40 and a 45 being almost a full inch diameter (3+ inches circumference) it is not unreasonable that the variation between different tires of the same profile/stated size would easily be within the range of ruining your diff.
Didn't even think about the worn down stock tires. It makes more sense now. Thanks for mentioning that...
thanks for explaining the tire size thing kingwrex. Moose i appreciate all the input and calculations. We all now know what not to do if you blow out one tire. Just replace all your tires and you'll be ok. Trust me its a lot cheaper and will avoid a lot of headache. I'm still working with subaru of america. They actually have been really helpful through all of this. I have nothing bad to say about them. I'll post again when everything is resolved. Thanks again guys for the input.
An option to replacing all 4 if the remaining 3 are still in good shape is to buy one of the same brand/model/size and have a place shave it down to match the rest. Not worth bothering with unless your other tires have a lot of life left in them though.
Since all new Subaru's sold in America are: 1) AWD vehicles 2) Require their tires to be at a near identical outside diameter to keep various drive-train components from breaking. Wouldn't it make sense for dealership service departments to save a few stock tire pull offs of different tread depths and or have a tire shaver so that customers won't have to buy a set of four tires due to the blowout of a single tire?
Finally got the car back a few days ago. Props to classic and to stephen. Sorry you had to do 2 diffs. lol.
:rofl: I used to do that in my Mistubishi Gaylant. I wouldn't dare do it in my Suby though, that's a big no bueno!
ah crap, i just replaced my front tires with two kumho asxs...and the backs are dunlops. I had to replace because of a bubble up front. The tire sizes are the same, and the thread depth is the same. Should i buy 4 new tires??