From dust to dust

[michael2e]

Well I finally decided to address those magnesium cam gear covers on my S2. As you may/should know the magnesium disintegrates over time turning the covers to dust. Ian at 944 online (no affiliation) ran a black Friday special on those masterpiece marvels of engineering from Travis at RennBay for $335. They're made out of aluminum and normally run much more than that. Which is why most of us keep putting it off despite the horror stories. At the same time I kept reading that many who replaced the covers claimed much improved idling and drivability which frankly seemed a bit far-fetched.

Dug into mine recently and was pretty shocked to see how bad they were. Nearly all the fastener points were disintegrating so I have no idea how the distributor cap and the Hall sensor for that matter were able to function as well as they did. I wasn't aware that even the small Allen bolts that hold on the Hall sensor could become impacted. One of my bolts was missing so the sensor was only held in place by one bolt and that was starting to go also. The new covers from Travis were so well-made they fit perfectly, included zinc plated mounting hardware and were straightforward to replace. And I have to say the idling and drive ability indeed are much improved. Don't wait any longer before yours return to dust also. Cheers and happy new year!

[michael2e]

Check out the hall sensor mounting points

And the finished product!

[Sansho]

Was it difficult to remove the camshaft timing gear? Any observations or insights? Thanks!

[michael2e]

I used a harmonic puller with 3 M5x80 bolts threaded into the rotor mount bolt holes directly in the cam gear. That also serves to maintain the timing relative to the camshaft. Mine was on pretty tight so I was unable to pry it off. There isn't room for a regular 3 jaw puller so this technique worked well.

[michael2e]

Ok so for a little more clarification on pulling the cam sprocket- Unlike the 951 the S /S2 cam gear is comprised of 2 parts: the toothed cam sprocket driven by the timing belt and an inner 3 lobed gear that articulates precisely to the camshaft by a woodruff key. The main cam sprocket is adjustable relative to the inner gear utilizing slotted mounting points and is designed with a wider woodruff key slot to accommodate adjustment. check out this photo which shows the wide alignment slot on the cam gear relative to the narrower more precise slot on the inner Tri-lobed gear. The wider slot thus allows for adjustment only to a point.

So the meaning to all of this is that assuming your timing is correct - the cam sprocket and inner gear are bolted together and precisely set at TDC - then if you don't secure the relationship of the 2 gears when you release the cheesehead bolt and go to pull them then you'll lose the timing. The solution is to place locking nuts on the 3 M5x80 bolts used in the harmonic puller and tighten them against the cam sprocket so it won't move relative to the lobed gear that the bolts thread into. See the previous picture for detail.

Per FSM the optimal timing is achieved for an S2 when the intake valve of cylinder 1 is open 0.75 mm +/- 0.1 mm at TDC For the S model it is 1.4 mm.