Repair-It

Here's one of those potentially satisfying adjustments that has a great ROI.

Evidently as the supercharger clutch wears the gap can change. Gaps that are too small or too big can cause issues including engagement jerks. I have a pretty annoying engagement jerk that happens when the supercharger clutch engages (it engages above a certain threshold, not sure if manifold pressure, throttle position, calculated power or what). It is the harshest in first gear as you'd expect (because torque multiplication) and can be followed quickly by a harsh 1-2 when warming up so it just ends up feeling quite unrefined. This promises to fix the supercharger engagement jerk which at least would remove one of them.

The supercharger apparently disengages next time you come to a stop and will re-engage using the same criteria. I have proven this because if I coast down to almost stopping but not quite (meaning I don't let the supercharger disengage) the jerk does NOT happen when I get on the throttle.

Here is a perfect video that explains and shows what this is all about.
https://www.youtube.com/watch?v=n0f7pNA_tNI

Hardest part is holding the supercharger from turning. I may have to buy a big hose clamp or improvise based on what I have laying around.

I went outside to measure mine. It is in excess of 0.68mm which is somewhere around 1.8x higher than spec. Wow.

Here are some interesting comments.

erikkaju
1 year ago (edited)
My M113k@G55 lost quite some torque over time. As it is my primary daily ride, I couldn't tell if I am just getting so used to the car or it is not fast anymore.
I followed the recommendation from this video and found out that my gap was 0.6mm.
Just got one of spacers removed and now the gap is 0.33. It's ridiculous how big the difference is from simply removing a tiny little spacer

Sensational feeling of sharp kompressor torque is back now. Loving it!

Martin Huusfelt
2 years ago
Howdy mate. Still driving UR E55? In hope so me to and found my way back to your post
So I recently noticed my boost "BOOST"
Is low can't get past 9 PSI and feels sluggish all is good but then remembered your super nice guide here and guess what I got 0.50mm gap is way to much right and also found 4 shims in nine hmmm can't believe it but is of will test tomorrow got a bit late bit will get back with results can't wait but what would u say happy a with such a large gap? How would car behave?

Martin Huusfelt
2 years ago
@Modify Or Die OOOOOH YEA BOOST:)
So removed 1 shim clearance now = 0.375 my sweet spot Boost went from 9 to 12 what an improvement I was shocked now it again pulls like a frk freight train and then 30 min into my drive an insane rattle tonight piston rod was broken but it seems my left front prim cat is in need of surgery really strange it sounds bad really bad and power loss until engine has cooled noise went away and power back = backpressure lol until drive for a whole story really odd it is not constant but was told by my AMG it looks like It has been modified who knows but will go for E55/CLS55 XSP Longtube headers

We'll just ignore the bad part there. But yeah this looks really promising. Hopefully I can simply remove a shim or two and get down to spec.

I went outside to check my bearing because it seems like this would be the ideal time to change that if mine was worn out.

I loosened the tensioner, slipped the belt off and spun the pulley. At first it was silent but I spun it faster and did hear some noise. Hmm. Then I grabbed the pulley and tried to rock it and....it rocks. It also moves in and out a little. This is no good. So I need a pulley bearing. Good news: https://www.ebay.com/itm/124190398837

They are only $45 for a genuine Japanese bearing (or so the description says). I have to wait another week but there is no point to adjusting the gap if the bearing is worn out. This may also decrease the gap a little which would be good. Excited to get this done and happy I checked. This is common and again with the prospect of driving 1,500 miles in a week, makes good sense to keep in top condition.

Got my bearing.

Did this today.

It was all fairly easy. I did have to buy a few things first. And from Harbor Freight I bought some stuff. I thought I bought a bearing installer but I bought the seal installer instead. No good for pounding out a bearing. SIgh. They were out of the bearing installer tool.

This morning I remembered to put the new bearing in the freezer.

And before I did this I did try slathering some valve lapping compound into the pulley gap to see if the surfaces could mate or something. This actually seemed to help. But the gap was still too wide so I had to do the bearing and set the gap next.

Pulled belt, slapped on the big hose clamps to hold the clutch hub, and was able to loosen the bolt without too much issue. I had the pulley off in 5 minutes, I kid you not. I found 4 shims installed. I was worried there would be less and I'd be out of adjustment, so that was good. They were not all the same thickness. One was on the thicker side but the rest were like 0.005" and 0.006" which is quite thin.

Getting the bearing out was also easy. I was worried about this. I was going to use a bearing installer but some people use a big bolt with some washers stacked. I didn't want to run back out. Fortunately I engaged my brain and realized I have some large 3/4" sockets which means....I have a bearing removal tool. First I pounded on it just flat on the wood because I didn't want to rest it on the lip of the clutch and I read the first movement is the hardest. So I pounded without too much worry and the bearing started moving just like it should. When it got to flush with the pulley I switched to supporting the lip with wood and the bearing came out the rest of the way with no issue.
Next I had to clean the pulley which was simple. Then I placed the pulley in a 200F oven for like an hour. When that was done I brought the bearing up to the kitchen and unpacked it, removed the pulley from the oven, placed it on the floor, and pushed the bearing right into it. At first it seemed to get hung up and I was all stressed. But I tried pushing and it slid right in, to the bottom of the pulley. Then I reinstalled the snap ring. Easy so far.
Now I had to tackle the shim situation. First I got a baseline with all shims. Definitely still had to remove. I tried removing stuff randomly and then realized I needed to measure the shims with my micrometer. This helped because I was able to estimate the combo of shims to get to the required gap. I got it right in the neighborhood, in the 0.35 to 0.40 mm range (yes I had to convert into and out of metric a couple times).

Road test revealed....still jerky engagement. Sigh. Ended up removing the pulley again, slathering some valve lapping compound onto the clutch hub and reinstall (loctite and torque again). The first engagements seem good but then it goes back to being jerky. I think it is better than it was but I was kind of hoping for perfection. It is what it is, but at least the bearing is good and the gap is adjusted properly. I'll put some miles on it and assess.

Might as well......get a bigger supercharger.