I installed the Powerflex urethane motor mount bushes that I purchased from George at Mini-Madness in Portland OR. Want to post my results.

Felt that I could detect definite torque steer with abrupt changes in the throttle settings. Also, saw the engine really twisting and moving when the car was on the dyno. Did the bush installation and tests sequentially. Started with the upper motor mount brace, drove the car a few days, then installed the others, etc. The upper brace motor mount bushes seem to make the biggest single difference in stabilizing the engine and reducing the already small torque steer that I noticed. I added a couple BIG steel washers to the large upper bush that mounts on the firewall. These washers allow the relatively narrow metal engine brace to bear on a much larger bush surface and probably reduces the bush compliance a little more. At least I feel better. The transmission bush was a bear to install and seemed to be the one that ended up giving me a low frequency vibration in first gear. I had to take the large cast aluminum motor mount completely off the chassis to get access to the transmission bush. With that motor mount off, the installation went peachy. I tightened that baby up real tight.

Overall, very very happy. Feel that there is no detectable torque steer with my overall chassis setup. The bushes have noticeably less compliance as measured by my at home durometer (pressing hard on the bush with a screwdriver) and with the bend test (bush in a vice and a screwdriver in the metal insert). Not an installation for the rank novice, except for the single upper stabilizer bushes. George is very helpful with installation suggestions. The Powerflex part numbers for the MCS motor mount bushes are: PFF5-104, PFF5-105, PFF5-107, PFF5-108.

Happy motoring,
John Petrich in Seattle

 

Are these replacements or additions? When I was at BMP, Al showed me some inserts that fit inside the stockers to tighten em up. Dont remember what brand they were tho...

 

i just put those same babies in my rig this morning.

they are two part: the two yellow parts sort of interleave with the existing rubber part of the chassis side of the mount, one above and one below. the engine side bush is more conventional, completely replacing the stock rubber bushing.

I also noticed a bit of low freq vibration at idle, but no biggie.

No clue about driving improvements yet.

I am interested in torque steer, something that has not been sufficiently explained to me for a fwd, transverse engine with equal length drive lines. They are not really equal length, only the part between the CV joints is the same length. If the overall shaft lengths are different, as they really are in the mini, you might get more torsional windup on one side cp to the other, but that is not an issue that would be corrected by stiffer motor mounts.

the engine tends to rotate on its long axis and is prevented from doing so by the stiffness of the motor mounts as min has located them. My guess is that a stiffer mount would let the motor not wind up due to the torque reaction to the application of power at the drivelines. This more limited rotation of the motor would reduce chatter upon power off and on and produce smoother traction.

 

Cheese and John (jlm),

Glad that others are interested in this question and maybe we can gather driving impressions and other observations that answer a few questions on this topic. John didn't specify whether he intalled both the large inserts that are applied to the chassis side of the engine stabilizers and the smaller bushes that are pressed into the mounts on the engine side of the stabilizers. I installed both the inserts and the bushes.

My comments on torque steer were possibly not correct. I was noticing a small amount of "torque steer like" directional instability under super maximum changes in engine torque. I was not always able to reproduce the phenomenon but when it did occur, it were an unwelcome surprise to say the least. I recognize that what ever is/was occuring is the result of my unique chassis setup and tire combination and hence I may be the only one noticing it. None the less, I zeroed in on the motor mounts as something I could stabilize in my car and see the results.

I don't understand torque steer in a FWD car like MINI at all. That said, there are two rotational components in a transverse engine car like MINI that need stabilization: the component about the longitudinal axis of the crankshaft and a component, normal to the crankshaft axis, about what ever passes for the pinion shaft in MINI's differential. I wonder if it is this second rotational component, around the differential, that theoretically might most affect steering with changing torque.

Hope others are motivated to report their observations.

John Petrich in Seattle

 

i installe them both, purple and yellow like an easter egg.