Or this. Available at most any local auto parts store for a lot less cost.
http://www.autozone.com/shop-and-garage-tools/valve-grinding-compound/permatex-valve-grinding-compound/526806_0_0/?checkfit=true Rick Brass Washington, NC From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Brian Davis via CnC-List Sent: Tuesday, May 10, 2016 8:47 AM To: cnc-list@cnc-list.com Cc: Brian Davis <brianwdavis...@gmail.com> Subject: Re: Stus-List Soft thumping/banging when in gear at low-rpm? Hi Dave, Is the lapping compound you used something like this? http://www.brownells.com/gunsmith-tools-supplies/metal-prep-coloring/abrasives/lapping-compounds/lapping-compounds-prod1137.aspx Regards, Brian 1980 Landfall 38 On Mon, May 9, 2016 at 9:24 PM, Dave via CnC-List <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com> > wrote: I replied earlier in haste, but another clue here is the forward-reverse thing as well as the low rpm banging only. The shifter moves a bronze clutch back and forth, this has a conical surface on each each end that mates with one mating female cone for forward, and the other mating female cone for reverse. In neutral, the conical clutch sits between both and engages neither. Forward is used a lot more, therefore it glazes first. As to rpm- these boats do not have thrust bearings so the prop thrust pushes forward on the engine/trans and ultimately the mounts. It does so via the trans, so the thrust overcomes the slip at a certain point and the banging stops. Before long it will slip irrespective of rpm, and get so bad that you will think the strut will be sheared off the hull. Per instructions in the internet I used valve lapping compound. Did not rebuild the gearbox, only lapped the cones. the halves use no gaskets, just silicone. I used a punch to mark the orientation of the cone and any other parts and was very careful to clean any residual lapping compound out of the transmission. Worked perfectly. Make sure you secure the prop shaft so it can't fall out. Dave. Date: Sun, 8 May 2016 15:40:53 -0700 From: Andrew Means <andrew.cnc...@gmail.com <mailto:andrew.cnc...@gmail.com> > To: cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com> Subject: Stus-List Soft thumping/banging when in gear at low-rpm? Message-ID: <etPan.572fc098.5095526e.13b@worsley.local <mailto:etPan.572fc098.5095526e.13b@worsley.local> > Content-Type: text/plain; charset="utf-8" Boat: 1977 C&C 34 Engine: Yanmar 3GM30 (F) Prop: 3 Blade Max Prop Recently I noticed that when engaged in forward-drive, at low RPM, it almost feels like something is banging against the bottom of the hull, like a piece of kelp or rope tangled in the prop. Once the RPMs get above 1400 or so the roughness goes away completely and everything feels very smooth. Sent from my iPhone _______________________________________________ This list is supported by the generous donations of our members. If you like what we do, please help us pay for our costs by donating. All Contributions are greatly appreciated! -- Brian Davis 1980 C&C Landfall 38 "Nina" <https://docs.google.com/uc?id=0BxaAN3B_Cl8LcHZVUWJZOFptWndLaDd6UjYtN1F4cDlXTk1R&export=download> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=icon> Virus-free. <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=link> www.avast.com
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