Sorry, the title should have read Destroyed Rear Differential.

I had rear tires put on after a blowout and just before rebuilding the top end of my motor. My rear diff destroyed itself a week later. I finished installing a new diff tonight and I am getting a whirring noise on engine braking. The noise goes away if I match revs. I checked the tire size and found that I had 225/75/16s on the front and the tire guy put 245/75/16s on the rear.

Would this cause my problem?

It is a 2003 Disco

Thanks.

 

I would have thought having different tires front to rear would have taken out your transfer case, but hearing how bullet-proof these transfer cases are, I suppose the differential might be the weakest link.

While I do not know for sure the different size tires caused the differential problem, I cannot stress enough how important it is to have the SAME sized tire all around. These are full time 4WD. Different sized tires rotate at different speeds. Having your front tires turn at a different speed than your rears on a 4WD vehicle is a recepie for disaster!!!!!

 

Ditto, and it could also be one of the bearing sets or a misaligned ring/pinion gear.

 

Thanks Mike. I was hoping you would chime in.

 

Having different size tires on the rear from the front wouldn't cause your rear diff to self destruct. The axle diffs only function in relation to the two wheels on that diff's axle.
It could cause issues in the center diff when locked.

It's coincidental.

That said, you should go back to the tire dealer, and unless you specifically asked for that size or they told you they were different from the front, have them replaced them with the correct size for nothing more than the price difference of the correct size, no other charges.
If you asked for that size or they warned you about the difference in size, then you'll need to eat the mounting and balancing charges too.

 

I'm confused. if the front wheels are turning faster than the rear wheel, which would be the case here, why would there not be the possibility of damage. The splines on the axels were fine but the other gears were what were destroyed along with their shaft whis is the pinion I believe. The new diff is still making noise so I think we can rule out ring and pinion misallignment.
The bearings are fine. What other variables are there. Recent top end rebuild. That should have no affect here.
The whirring noise is still going on so the problem that caused the rear diff to fail is still present.
Please let me know if I am wrong here but the problem has to be coming throuhg the transfer case which would lead to the front diff and the trans. The trans seems to be fine so it would lead me to believe that it is wheels or transfer case. Correct?