According to the guys at Power Engineering, the front and rear rollers are independant. With my car on the rollers, the rear wheels are visibly turning much faster than the front.
Apparently its fine on the road where everything turns at roughly the same speed.
The difference between the axle speeds on the RR would fook it up completely.
I've been having a chat today with a 4wd rolling road operator, and there are some points of interest.
When doing a power run you will dial in fixed load conditions, which supposedly replicate vehicle weight, "steepness of hill" you'd like to climb, etc.
There is no facility to input torque split at the centre diff.
If a high enough load is dialed in, then theoretically you could quite possibly beat the VC.
When doing a speed hold, apparently you dial in a speed that you don't want to exceed, and the roller retarders do just enough to keep to that speed. This, apparently, is not so hard on the centre diff.
The trouble with a rolling road, as opposed to the real road, is that in the real world your 65% rear bias is helping to push the car up the road, so taking a lot of the load off the front. I don't know that 4wd rolling roads can replicate this.....
I would be interested to hear any input from RR operators.
Incidentally, the guy I spoke with has sent me several VCs over time, and the ones he sent were knackered through old age. As I said earlier, I see many that have been condemmed by a rolling road, only to find nothing wrong with them.
Interesting topic this
