The Independent American Magazine for all Mini Owners
Issue link: http://mc2.epubxp.com/i/33538
An exploded view of the ATI Super Damper (www.atiracing.com). Rebuilding is done by replacing the o-rings in the inertial weight. the longest crankshafts of mainstream engines. Very short crankshafts (such as those used in our compact inline four-cylinder engines) tend to have less of a problem with crank oscillation. And as the power or redline in any given engine increases the amplitude of the crank oscillation increases too. The stock harmonic damper is also the crank serpentine belt pulley, basically serving a dual purpose. But it’s not conventional in design: it actually has two elastomers in it: one is for the conventional harmonic damper; the other is a softer “shock absorber” on the serpentine belt. While no one has confirmed this for me, I think the second elastomer is to soften the pulsing of the supercharger drive. It’s interesting to note that this is the rubber part that fails in the first generation supercharged cars. But when it fails, it fails big! As you can see in the picture, the two parts come completely apart. So, what does the aftermarket have to offer? There are four options that I know of: The stock part will last you for quite a while, and really, changing this part out once should get you to 200k miles or more. There are lots of companies that make a non-damper pulley. Designs vary, but all of them are very light and have no harmonic suppression capabilities at all. While they do save weight, you will never find one on my car, even with the very stiff, short crank used in our compact engines. But many have been bought, and there are many happy owners out there. To each, his (or her) own! But to my mind, looking elsewhere to reduce the spinning mass of the driveline is a better way to go. As far as aftermarket harmonic dampers go, both Fluidampr and ATI Performance Products make options for the MINI. Waylen Hudsucker of Way Motor Works has worked with both, and he prefers the ATI SuperDamper, a rebuildable unit. What’s interesting here is that they use different energy dissipation mechanisms. The ATI uses precision elastomer, and the Fluidampr unit uses a silicone liquid, like what’s used in shock absorbers. What’s more ATI crank dampeners are the only ones used in NASCAR competition, which speaks volumes to their reliability and the company’s credibility. I dug into this a little deeper, and found out some interesting information. The use of elastomer results in what is known as a “tuned 36 MC2 Magazine www.mc2magazine.com damper.” This means it works best at certain frequencies, and less well at others. The fluid based units don’t have this limitation. But what’s interesting is that if you get into the nitty gritty of all this, while the fluid based units aren’t frequency dependent, they do allow a larger amount of crank twist than the elastomer units, both on and off the designed frequency! (For you nerds out there, see “A Practical Treatise on Engine Crankshaft Torsional Vibration Control. SAE Paper SP-445” by R.C. Bremer Jr.) Replacing The Damper In theory, replacing the damper is a pretty easy job. But then, the real world is often different than theory. First off, you need some special tools to do the job. You need a belt removal tool, a harmonic damper removal tool, and a special pilot gizmo (Thanks Way, for lending me one of yours!) so that the harmonic damper removal tool can do its job. Also an air wrench or large breaker bar, and the standard sockets and the like will be needed. The task is similar on all the cars, so if you have a first generation Cooper, or a second generation car, make sure that you read up on the different details for your car before you start. The generic harmonic damper removal kits have lots of bolts, just not the right ones for our cars! So off to the hardware store to get some M8-1.0 bolts that thread into our harmonic damper. Now I had everything I needed to get the job done (so I thought) and I set to work. It starts easily enough: Jack up the front end and take off the passenger side wheel. First, I took off the fender liner. This is a pretty easy job, on my ‘02 S, the liner is held on with some plastic fasteners and two Phillips head screws. Just don’t forget the two you get to from the bottom of the car. One is up by the bumper lip, and one by the side molding. Now the crank pulley is exposed, and it’s time to spray some rust remover onto the threads. You see, this part gets exposed to the elements, and it rusts like crazy. Little did I know that this build up of corrosion and crappy hardware store bolts were the beginning of my undoing... Now I use my belt tensioner tool and an unbent wire hangar to take the tension off the serpentine belt. Once the tension is off the belt, it’s easy to slide it off the idler pulley and then it’s easy to remove from the