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alternative throttle shaft bushings?

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don

Posts: 554

Joined: Fri Oct 01, 1999 12:01 am

Location: Spokane WA USA

Post Tue Feb 29, 2000 4:53 am

alternative throttle shaft bushings?

I'm rebuilding a linkert, and wondering how to improve the wearability of the brass throttle shaft to bushing, and seal it as well.
I have tried 1/8" round teflon packing rolled flat then spiraled in place of the steel bush, seals well, but i don't trust it. can envision it working it's way out on the road in the middle of nowhere.
I am leaning towards trying a teflon tubing, [tefzel],exellent mechanical resistance, good chemical qualitys, which comes in the correct O.D. but the I.D. is .230"- great if you have a worn shaft.
Any thoughts would be appreciated!
don
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dotman

Posts: 582

Joined: Fri Oct 01, 1999 12:01 am

Location: meridian, id. usa

Post Wed Mar 01, 2000 2:05 am

after ya put the teflon in ya might try putting a dab of clear epoxy on both sides (outside sides) to keep it where its suppose to be
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Cotten

User avatar

Posts: 2679

Joined: Thu Sep 30, 1999 12:01 am

Location: Central Illinois, USA

Post Wed Mar 01, 2000 3:43 pm

Retaining the bushings should be no problem, since the butt of the shaft retains the lower one, and the linkage clamp would retain the upper. I am sure you would want to lathe cut a continuous bushing rather than a split or rolled one; The whole idea is to prevent leaks as well as bear the shaft. There should be no problem cutting them from 6/6 nylon or any number of resilient plastics, but the problem is one of a perfect final fit. It would not be able to be hone fitted as a metal one would. Similar to this application I am working on a modern material replacement for the non-compliant brass manifold seals. I am sure that the carb bushings are just one of dozens of improvements in stock design that could be made with a simple modern material replacement.
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dotman

Posts: 582

Joined: Fri Oct 01, 1999 12:01 am

Location: meridian, id. usa

Post Wed Mar 01, 2000 3:53 pm

Actually teflon can be machined like metal if you use the proper grade or something like delrin which is a real hard hi temp chemically resistant plastic. cuts like aluminum
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Cotten

User avatar

Posts: 2679

Joined: Thu Sep 30, 1999 12:01 am

Location: Central Illinois, USA

Post Thu Mar 02, 2000 3:43 am

Dotman! The problem is in the honing; compliant 'plastics' embed the abrasive from most honing ('xept mebbe diamond)techniques. Reaming is usually inaccurate because the material will spring back tighter than what the reamer would normally cut out of brass or iron. This would make for a great seal, but it would be rough on your right wrist.
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dotman

Posts: 582

Joined: Fri Oct 01, 1999 12:01 am

Location: meridian, id. usa

Post Thu Mar 02, 2000 3:41 pm

Delrin is used for bushings in a lot of critical applications due to its machineability. but then again why not get some small steel tubing from the local ace hardware store that will pass the I.D. O.D. test and use a tube flare on the end that needs the flange then hone that to the size of the shaft?
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don

Posts: 554

Joined: Fri Oct 01, 1999 12:01 am

Location: Spokane WA USA

Post Thu Mar 02, 2000 4:29 pm

Thanks, found the Delrin hollow rod in the Mcmaster-Carr Cat. O.D. is 1/2" w/1/4" I.D. X 5'long. <$10.00
Should be easier to finish down the O.D. for slight interference fit, just have to come up with or make a decent 1/4" arbor for machining.
don
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Dusty-Dave

Posts: 887

Joined: Tue Oct 12, 1999 12:01 am

Location: Ojo Caliente,NM,USA

Post Sun Mar 12, 2000 5:09 am

Don:
Chuck Miles
RTE. 30A
Box 150
Sloansville, NY 12160
Phone: (518) 875-6745
builds teflon bushings for Linkerts. If you don't tell him that it's not going on an Indian you will probably save your self some abuse.
Dusty
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don

Posts: 554

Joined: Fri Oct 01, 1999 12:01 am

Location: Spokane WA USA

Post Sun Mar 12, 2000 6:59 am

Thanks Dusty!
I'll put some in my M-344 too!
don

[This message has been edited by don (edited 12 March 2000).]

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