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Thread: Donuts for Retro Fronts

  1. #1
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    Donuts for Retro Fronts

    To all of you who rerubber your fronts. What donuts do you use?
    Anything worth doing is worth overdoing

  2. #2
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    Oct 2012
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    Don Alpha hard or x-hard.

  3. #3
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    Thanks Greg.

    I don't see those at my usual on line supplier. I'll look further. I'll see if Mimi wants to get them this Saturday at The Track.

    Too bad it has to be sponge rubber. Black Delrin would sure hold up.
    Anything worth doing is worth overdoing

  4. #4
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    Post

    Be careful what you ask for. The delrin may not wear out but it will definitely upset the handling of your car besides being Very Noisy. While wonder rubber is the default rubber currently used on fronts there has been some testing and race use of softer rubber with great results on some tracks and car types. Softer than wonder fronts will settle a F1 down in many instances. I have used Alpha treated donuts for fronts with very good results for several years. The one down side is they do wear faster than wonder, the "cost" of pushing the boundaries. Your results Will Vary, as mine do.
    Tom Hansen

    Our Gang Racing
    Cukras Enterprises

    Team Camen


    Keep on Keeping On

  5. #5
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    Cool Tom . That's the kind of info I was looking for. I'm newly experimenting with fronts.

    I'm turning out some white Delrin wheels. Next question: will the 3M yellow snot adhere to Delrin?
    Anything worth doing is worth overdoing

  6. #6
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    Quote Originally Posted by dlatch View Post
    I'm turning out some white Delrin wheels. Next question: will the 3M yellow snot adhere to Delrin?
    Delrin is notoriously difficult to bond. If you're going to try 3M 08001 Yellow Super Weatherstrip and Gasket Adhesive (yellow snot?), proper preparation may make all the difference. First, scuff sand the bonding surface (Scotchbrite 7440-Tan pad or 120/150 grit sandpaper), then clean with 98% isopropyl alcohol or lacquer thinner - donuts also. Allow to dry completely. Then coat both bonding surfaces with a thin layer of adhesive and allow to dry. Dip both tire and donut into lacquer thinner and quickly assemble. Clean off any excess adhesive, and set assembly aside to dry.

    I'd only build one set of front tires to test the 08001 adhesive - it it doesn't prove successful, you may have to switch to epoxy or cyanoacrylate types.

    Cheers!

  7. #7
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    Many years ago, I used some delrin fronts from England for 1/32 Euro cars. The NOISE they made on they track was totally annoying. I found neoprene tubing that I could lathe tire donuts from and glue to the rims. Noise was gone and the extra hardness was also eliminated - the 'prenes are soft enough to absorb SOME shock of the roadbed and not wear like foams can. BUT if the rules say "foam" then neoprene could be illeagal like multiple O-rings.

    JK Products lists donuts for all rubber types including three size of hard foam fronts.

    ADHESIVE: The aromatic countertop glues that are commonly used in braiding tracks is also used for bonding tires to rims. the portable tube of 8001 weatherstrip (yellow snot) is just as good as opening the big can for quikies.
    Last edited by Ramcatlarry; 01-10-2016 at 10:27 AM.
    l.d. kelley, M.A. Ramcatlarry@aol.com

    60 year pin 1959-2019
    Racing slot cars in America
    USRA 2019 member
    IRRA, ISRA/USA, Hardbodies 1/24 &
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    retired raceway owner 1992-2007
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  8. #8
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    Rigid (delrin) will not be as fast as softer, though as far as I know no one has worked out the optimal degree of softness. Current Horky 1/32 F1 fronts are about the softness of soft wonder rubber, I think. (I don't race retro, but we have the identical issue in 1/32 F1 Eurosport.)

    Greg

  9. #9
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    I wasn't serious about delrin as the actual tire since, as I said, it has to be sponge by the rules. But like to experiment and I figured the comment would flush out some good info as it has. Thanks all. (generally...by the time I think of it...its been done.)

    After Hermits cautions I figured I'd stick to aluminum. BUT (I'm new to Retro) I just noticed the Bartos Fronts...sure looks like black Delrin. Or is it Acetal? Surely at 25 bucks a pair someone is re-rubbering them.

    I have both materials. The black is Acetal the white is Delrin. I know there is a difference but I don't know what that difference means in terms of yellow snot-ability.

    Give me week to get the donuts and I'll have an opinion.

    (i don't mean to reinvent the wheel...I just like scratch building and I have a small lathe)
    Anything worth doing is worth overdoing

  10. #10
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    You might want to check out a pair of ARP/Chubby fronts. The rim is large so there is less rubber. In tests they made a detectable difference compared to ones with softer.taller rubber. They are made in all three IRRA sizes.

  11. #11
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    Acetal copolymer is the generic name that Dupont has as the trade name "Delrin"
    l.d. kelley, M.A. Ramcatlarry@aol.com

    60 year pin 1959-2019
    Racing slot cars in America
    USRA 2019 member
    IRRA, ISRA/USA, Hardbodies 1/24 &
    1/32 - Great Lakes Slot Car Club
    retired raceway owner 1992-2007
    Omni/Cidex service center

  12. #12
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    The ARP fronts look just like the Bartos. Black plastic. Has anyone re rubbered them? Does the adhesive adhere? I guess Chubby or Bartos would know. I guess I'll find out when I try it.

    I couldn't get CA glue to hold a smooth magnet to the black stuff.
    Anything worth doing is worth overdoing

  13. #13
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    Pretty sure they use 3M contact cement.

  14. #14
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    Click image for larger version. 

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    I went straight to plastic bonding Loctite epoxy. At the website it names Delrin as one of the plastics it is supposed to work with. However, the epoxy that got on the face of the wheel was easily scraped off with my fingernail so, we shall see if they hold up to actual track time. They are alpha hard wonder yet, not as firm as JK extra firms.

    I'm new to building retro and wanted to try a wide support front end so I turned my own wheels. No ball bearings, no set screw, minimal hub, drilled. Total weight 1.0 gram. And white looks better than black I must say. I did have to make a special fixture to hold them on the Hudy. Hopefully a wide support front can work.

    Picture link posted twice...I'm rusty at posting images
    Anything worth doing is worth overdoing

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