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Engine basics => Engine set up tips => Topic started by: louie klein on February 14, 2012, 08:27:50 AM

Title: Mylar disc readhead replacment
Post by: louie klein on February 14, 2012, 08:27:50 AM
Hey buds, I got hold of two 35 Redheads and I am taking them apart to clean up. I have noticed that the mylar disc on the conecting rod is shot. I have mylar but my question is how do I keep it on the rod? Is zap good enough to hold it if it is clean? Thanks.---LOUIE  H^^ H^^ D>K
Title: Re: Mylar disc readhead replacment
Post by: Jim Kraft on February 15, 2012, 07:26:00 AM
Louie; If you are talking about the Teflon button that goes in the crankshaft, they are held on by the back plate. The part that goes into the crank is long enough that it won't come out. Its main purpose is to keep the steel crank from wearing on the back plate.
Title: Re: Mylar disc readhead replacment
Post by: louie klein on February 15, 2012, 09:04:02 AM
Okay Jim I get it now. It has a shoulder. The three I have apart are worn flat, hense my confusion. Thanks.---LOUIE  H^^ H^^ D>K
Title: Re: Mylar disc readhead replacment
Post by: Jim Kraft on February 15, 2012, 04:50:58 PM
Louie; I think yours are OK. They originally are very thin and flat. McCoy Red Heads have quite a bit of play fore and aft in the crank, and unless they have had an electric starter used on them, the button does not even wear on the back plate. The crank is always pulled forward with the prop.
Title: Re: Mylar disc readhead replacment
Post by: louie klein on February 16, 2012, 05:58:06 AM
More good news! Thanks Jim.---LOUIE  H^^ D>K
Title: Re: Mylar disc readhead replacment
Post by: Chris Wilson on February 16, 2012, 04:50:30 PM
The crank is always pulled forward with the prop.
And the rod tends to migrate backwards to the back plate primarily through crank pin flex and secondly through the intake charge being directional.

The best fix for this problem, if indeed it is one, is the use of a hardened steel disc attached inside of the back plate.