Macht Schnell power pulley - steering issues?

[CamasM3e93]

For most S65 stock set ups, the accessory belt is double sided and the outside of the belt drives the power steering pump pulley, which is also grooved. The Macht Schnell power pulley kit swaps the stock PS pulley with a smooth surface, larger pulley and uses an off-the-shelf single sided belt. The overall effect as intended is to reduce the overall load on the drive/crank pulley and to reduce the rotational speed of the power steering pump for both power and steering feel benefits.

There's slightly more wrap of the smooth PS pulley surface than stock, but when the kit came out a decade ago there was speculation that the wrap of the MS PS pulley wasn't adequate for use of a non-ribbed side of the accessory belt and that the PS pump pulley would experience slippage at high RPMs. Knowing that theory can often not reflect reality, curious if anyone has experienced an issue on this. For those of you using this kit, have you had any power steering pump issues at high RPMs?

[darren p.]

I haven't had any issues like that but it does squeek a bit if I go full lock which I assumed was the belt slipping.

[Track/S]

On s65 there are 2 power steering pumps, one turns to the right and the other to the left, you can't make them work in reverse if the original pump works in the other direction.
Pump with smooth belt turns to the right and grooved belt on both sides turns to the left.

The Macht Schnell kit works only for one pump version.

[GinTonic]

No, there are not issues at high rpms. Just install it an enjoy. You're overthinking it.

[CamasM3e93]

Originally Posted by GinTonic

You're overthinking it.

Lol no surprise there!

[GinTonic]

If you don't like it, you can switch back. Takes anywhere from an hour to two hours to do.

[CamasM3e93]

Originally Posted by GinTonic

If you don't like it, you can switch back. Takes anywhere from an hour to two hours to do.

It’s in the car now, just buttoning up after a major project to remove the Harrop and various odds and ends. I didn’t pay attention when I ordered the MS kit and bought the m5 variant. I figured they were the same but the S85 kit uses shorter belts (same MS pulleys on both cars). So in the process of purchasing the correct belts I noticed the one sided versus two sided accessory belt detail and as you astutely pointed out, overthinking ensued.