Timing Gears

[dick campbell]

What back lash should there be between the crank and camshaft gears?

[gordon higginbotham]

Dick,
I see that the STD forum has come up trumps again with Jim"s answer! I am trying to find an answer for the 14/45 as I suspect that it would be similar to the 105 but no luck so far.

[gordon higginbotham]

I was in touch with Martin Lawrie and he has a new timing gear he has fitted and reports that the backlash is .008" - within the range quoted by Jim.

[dick campbell]

I agree....0.008" it will be.

[Martin Lawrie]

....and I can now report that the 0.008" provides silent running with the steel gears provided by Foppe de Hane.

[Doug Reid]

If it helps, below are the notes I made when trying to work out the backlash between the crank timing gear and fabroil cam gear. Tests were done with Vinnie Rawlings: -

Backlash – camshaft gear on test rig (18HP)

Measured at gear o/o

Unused Roots Fabroil gear 0.020”
Doug Reid's OE Fabroil gear – 68k miles 0.040”
New Fabroil gear (Foppe D'Hane) 0.047”
New Fabroil gear (Vincent Rawlings) 0.024”
__________________________________________________ ____________

Test rivet length 1.030”
Hub assembly thickness 0.910”
Rivet protrusion 0.120”

Basic rivet length 1.030”
+ 0.030 parallel at 3/8” diameter 0.030”
1.060”
Drilled letter B 0.238”
Rivet diameter 0.238”