Diff Question.

[Bmw.wp]

Hi Guys

Will it hurt your diff, if driving with 1 18inch mag and a 1 16inch mag at the rear.?

Or any different size mags at your rear when using your sparewheel.?

 

[applehero]

I would say what is more important is the rolling radius of the rear wheels is the same (if we are talking about a rear wheel drive car). If the car is four wheel drive, you will have a problem if the rolling radius's arent the same. Also, if you have an M car - so likely a limited slip diff, this may be a big problem.

Rolling Radius is the distance from the centre of the wheel to the ground, with the wheel on the car and the full weight of the car on it.

 

[Philip Foglar]

It also depends on how long and how hard the car is being driven - the diff's function is to deal with this anyway, just it is seldom that you are stuck going around a traffic circle.

Now play with this scenario - you are driving an E90 (or any of the cars with RFT's and no spare) and you have a rear puncture. You have no choice but to drive to your destination, albeit at no more than 80km/h - the diff is then also being put to the test from a load and difference in diameter situation.

 

[applehero]

It also depends on how long and how hard the car is being driven - the diff's function is to deal with this anyway, just it is seldom that you are stuck going around a traffic circle.

Now play with this scenario - you are driving an E90 (or any of the cars with RFT's and no spare) and you have a rear puncture. You have no choice but to drive to your destination, albeit at no more than 80km/h - the diff is then also being put to the test from a load and difference in diameter situation.

Yeah, agree. Two wheel drive with an open diff, not really a problem. Four wheel drive or limited slip and wrong Rolling Radius's I wouldnt recommend!

 

[P1000]

Yeah, agree. Two wheel drive with an open diff, not really a problem. Four wheel drive or limited slip and wrong Rolling Radius's I wouldnt recommend!

diffs - even open ones - wear out surprizingly quickly when they are driven constantly with different output speeds.

 

[Philip Foglar]

Yeah, agree. Two wheel drive with an open diff, not really a problem. Four wheel drive or limited slip and wrong Rolling Radius's I wouldnt recommend!

diffs - even open ones - wear out surprizingly quickly when they are driven constantly with different output speeds.

Well, makes me wonder with some E90's that have mysteriously developed noisy diffs - I remember Colin (Herr BMW) had that happen. So in other cases, I wonder if this may not have been caused by driving with the scenario I mentioned above.

 

[Bmw.wp]

Thanks Guys. :ty: