Andrews R5 Cams End Play

[JW113]

I picked up a set of Andrews R5 cams, and tried to install them yesterday. Everything went well until I checked the end play. Cams 1, 2, and 3 all had about .030" (no shims) with just the end plate. Cam 4 however has zero end play. In fact, less than zero, as when I tightened  the gearcase screws (hand snug), the cam binds up. WTF?

The end plates are .063" thick. I don't know if they have thinner end plates, don't think so. Measuring the end to end thrust surface on these cams is kind of a pain, need to figure out a way but it doesn't really matter, #4 is too long.

Maybe use individual thick shims instead of the two end plates? But then the shims would wear against the aluminum case. Plane the front endplate down at #4 cam? Chuck the cam in a lathe and cut the inner thrust surface back?

Anybody ever run into this? Guess I could call Andrews.

-JW

[Buglet]

   If ever thing checks out OK and nothing else is causing the problem, have someone with a surface grinder grind the end plate. Been there done that.

[JW113]

Using a fiddle maker's caliper, I found the thrust surfaces on the are different:

P Cam:    2.420"
Andrews: 2.460"

All the other cams (#1 - #3), the thrust surface measurements were essentially identical.

However, looking a little closer, this vintage of cams has a press on tachometer drive gear, which is where the outer thrust surface is located. And doing some measurements with the dial caliper, I found the thrust surfaces different between the two cams.

Gonna pop the tach drive gear off the P cam, and put it on the R5. Hopefully that will be the culprit.

-JW

[JW113]

OK before anybody beats me to it...

Yes, that was some STUPID logic! NO, the tach gear is not the thrust surface. Sheesh.

However, pushing the tach gear off did reveal the root cause of this problem. Since the thrust surface of the cam is down below the rim of the tach drive gear, I could not see exactly what was going on. With the gear off, and comparing the stock cam to the Andrews cam, the end of the Andrews looked kind of "funny". With the help of a magnifying glass, I could see there were SHIMS on the end of cam! A little stack of them, all glued on the cam. Using an X-acto knife, I pried them off.

I'm pretty sure it's going to work now. Doh!!


-JW

[JW113]

 

Fixed.

-JW

[Buglet]

  That is why its good to check things out more then once before moving on to the next step. Glad you found the problem.

[JW113]

I think I would not have found the problem had I not removed the tach drive gear. Those shims were stuck pretty tight to the cam, almost as if they were glued. Also they are down inside the tach drive gear, very hard to tell just by looking that they were not the end of the cam.

-JW