I freakin' love it. Perfect in all aspects.
The body roll and understeer in the Mz6 is excessive to say the least. Tanabe NF210 springs helped a bit, but I really wanted to lock up the rear with a stiffer RSB to help the car through corners without adding harshness to the ride.
I kept reading about how people with the Corksport RSB get a bothersome clunking noise and some have reported it rubbing in areas. Did not want that. As much as I also didn't want a giant overkill bar, I picked up a used JBR RSB for cheap and gave it a shot. The car cornered absolutely flat, but the rear end was far too stiff for city roads. Out came the JBR RSB and in went the stock bar, sacrificing handling for comfort as any pansy would do.
the ride was still fairly stiff with the OE RSB -- presumably because I severely overtorqued
the brackets (and the bushings are not lubricated). The service manual calls for the nuts to be tightened to 16-19 ft-lbs
to just barely compress the rubber bushings. I cranked them down to probably 50-60 ft-lbs. When I went to remove the OE bar, it was so bound up in the bushings that I couldn't rotate it even with the nuts loose. I had done the same thing with the JBR RSB. Installer beware.
I found the Progress RSB
(see first post) and went about installing it this weekend.
I measured the two bars:
This was interesting since the Progress website
lists the OE bar at 18mm. It's super wimpy either way. The Progress bar is a monster comparatively. It felt very strong and the welds/brackets looked good. (It's a steel bar woo!)
Since this bar isn't marketed for the 6, I went ahead and overlaid it with the OE bar to make sure the dimensions were comparable. We good.
Compared the brackets. Digging the slotted holes on the Progress brackets. Made install much easier.
Note: I despised
the giant billet brackets that came with the JBR RSB. It was nearly impossible to get a tool in there to tighten the nuts. That's one of the reasons that I overtorqued them -- if they had come loose, I probably would have just put the car into a lake rather than deal with them again.
Compared the bracket placement. Everything looks good--into the car with you!
Now we get to the part where I overtorque the mounting brackets again NOT SO FAST
. These brackets have stiffer polyurethane bushings that don't need to be compressed. I was able to tighten the brackets all the way down without fear of binding the bushings. I believe ecstatic
is the word. I cranked the nuts down, locking the brackets onto the subframe, and could still freely rotate the bar. This was not the case with the OE or JBR bars. I would also not even consider describing it as "loose" since the stiff poly bushings don't compress like the rubber ones. They act more like a lubed up plastic sleeve than anything.
Clearance check -- all is well. I should note that I slid the brackets up/towards the front of the car before tightening the nuts to maximize the clearance for the ends to rotate. It looked like it would have been fine if mounted all the we down/towards the rear, though. No concerns about clunking here.
Perfection. The car rides better than I can remember. The bar is free to rotate in the poly bushings as the suspension travels over bumps, so no more jarring railroad crossings. The body roll is greatly diminished. The reduction in understeer is already comparable with the JBR tank barrel on the soft setting, but the firm setting may be even more fun. I installed it on the soft setting to start and will keep it there until I get my Koni FSD's installed & broken in.
I think that's all I have to share on this bar. It's cheap, well made, and functionally perfect for me. Very happy customer here.