So I'm at 74,000 miles on my M and have well over 10,000 hard track miles on my car since installing my first ESS Vt-1 kit. As any car guy would I noticed a distinct change in sound quality of my motor since upgrading to the 525 kit a few months ago, and the car just did not pull like it should with 525 hp. (My evidence of this was my 60-130 time of 10.4 sec, only 0.3 sec faster than my car in VT-1 trim). I knew I was making the appropriate boost and wasn't having belt slip with the proper belt and pulleys installed, and my temp stays is excellent with my new 34 row Setrab cool upgrade. At any rate I thought a few things needed addressing at this point motor wise.
1.) Vibrational damper: At over 70,000 miles the rubber in this was quite brittle from track day heat and I know of motors that have blown on track from its failure so this was a no brainer.
2.) VANOS and exhaust hub replacement. This was softer call but a failed vanos /loose bolts/broken vanos exhaust hub can also grenade a motor on track. Also i had a hypothesis that it may be the cause to my car not running as strong as it should.
3.) Clutch /flywheel replacement: This was easy at my torque levels I wasn't having slippage with track use but the clutch felt like it was down to a very thin layer of active material. Clutch travel was also extremely light and very deep to the engagement point. I decided to go with the Sachs HD/ JB racing aluminum flywheel combo that Turner motorsports sells. It is OEM quality and durability , (which is key since it will be seeing 150 gps and 8100rpm every lap at my favorite track), and the flywheel was specifically engineered and tested with this sprung hub clutch. (a sprung hub clutch greatly reduces flywheel noise and rattle). The upgraded pressure plate is rated to hold 50 wtq more than the stock clutch and combined with the OEM organic lining would give OEM clutch control, i.e. not be an on /off switch. Here are the pics from the install including shots of the OEM clutch and flywheel. I think it shows just how stout or stock clutch is after 72k and 10k track miles , and that proper heel toe downshifting is really kind to your clutch
.
Review after the install:
1.) VANOS/flywheel: The car pulls much harder now and is more eager to rev at the top of the rev range. Certainly the 12 pound flywheel helps this but I believe the VANOS has improved midrange and top end output considerably as well. The car idles much smoother now(0 idle hunt).The car now will spin 285 r comps from a roll in 2nd gear from 5k upwards, and on a quick WOT 2-3 shift will spin through the majority of 3rd gear as well. It was not this strong before. Then there is the sound of the flywheel at 8100rpm.....
Sweet Jesus it sounds like a proper race car now. I'll post some in car vids from the track next week when i head back to Roebling. Surprisingly their is very little rattle , even next to building from the flywheel( my GTR flywheel was much louder). Also the car has plenty of torque output so stalling even in stop and go driving is not an issue.
2.) SACHS HD clutch. MY favorite mod I've done period. Transforms the car, it feels like a GT3 clutch now and that is a compliment. Yes the clutch effort is more substantial , but I can feel the engagement point now and it is much , much higher up . Way easier now to rev match than the worn stock clutch, even with the 12 pound flywheel.
I will be putting it back on the dyno next week before the track and will rerun the 60-130 as well.
George