Author Topic: Any interest in RC style swingarms? (Read 4011 times)

Turbogrimace · « **on:** October 19, 2009, 09:09:05 AM »

I have been tossing around the idea of getting a few RC style swingarms made, but I wasnt sure how much interest there would be. I am referring to the RC drag swingarm with the three axle positions and the three shock angle positions. There's more room for a wider tire, extended wheel base, and shock adjustments.

I wanted to see how much interest there was before I got into it. How many of you have been looking for, or have been interested in an RC swingarm? If there's enough interest, I can get a price quote out pretty quickly.

Thanks fellas.

oldfett · « **Reply #1 on:** October 19, 2009, 05:24:52 PM »

To be perfectly honest I didn't even know RC made swingarms! Any chance you could throw up a pic (I'm assuming you have one)?

bucky katt · « **Reply #2 on:** October 19, 2009, 05:56:28 PM »

perhaps one a hair shorter for quicker handling?

MCRider · « **Reply #3 on:** October 19, 2009, 06:01:58 PM »

There have been some pictures of one kicking around here but I don't remember where. Maybe it was on satanicmechanic.com?

Anywho, it was rectangular stock. The ends had the 3 positions laid out and a ractangular block slid into the ends and could then move back and forth for chain adjusting purposes. I think the first position was slightly shorter than stock, or it could easily be made that way, and could be adjusted into the stock length. The next 2 axle positions were then longer. The 2nd positon would be good for touring and the 3rd for the strip.

Turbogrimace · « **Reply #4 on:** October 20, 2009, 05:29:43 AM »

MCRider's got it. It's a really nice piece. A friend of mine builds race chassis and is about to lose his shop. He needs a few projects to stay afloat and something like this would be pretty easy for him. I'll see if I can get a picture of one for you guys. Thanks for the responses.

Actually, here's a picture of one on my friends bike.

fishhead · « **Reply #5 on:** October 20, 2009, 05:47:13 AM »

Heres 2 pics.

MCRider · « **Reply #6 on:** October 20, 2009, 06:14:29 AM »

Is the front position shorter than stock?

ColinMc · « **Reply #7 on:** October 20, 2009, 06:31:14 AM »

I'd be interested but it would be VERY dependent on price...can you give a ballpark figure just so I can know if this is way out of my league or not?

I am also curious if the shortest position is either equal to or shorter than stock...?

Turbogrimace · « **Reply #8 on:** October 20, 2009, 06:59:42 AM »

I'll have to take some measurements and the price would be dependent on how many people were interested. I would like to say about 300 for a ballpark.

MCRider · « **Reply #9 on:** October 20, 2009, 07:09:03 AM »

Quote from: Turbogrimace on October 20, 2009, 06:59:42 AM

I'll have to take some measurements and the price would be dependent on how many people were interested. I would like to say about 300 for a ballpark.

There are a few downsides. One must fuss with splicing in chain sections. Or have multiple chains and masterlinks to do it right.

Also, fender clearance front to rear becomes an issue at the extremes.

Not so much for an open tail racer, but a street bike.

Room for a wider tire is nice, either for looks or purpose.

kos · « **Reply #10 on:** October 20, 2009, 07:31:38 AM »

From the RC Engineering catalog (1974) here is the description:

A fully adjustable, lightweight arm designed for road racers, cafe racers or street class drag bikes. Made of 4130 Chrome-Moly tubing, this unit is 30% lighter than stock and twice as strong. It features an exclusive R.C. 3-way axel location that allows for standard wheelbase, 1 1/2 inch extension, or 3-inch extension mounting. 3-position shock mounting is also provided. Due to its light weight and added rigidity, this unit is ideally suited for use on pro-stock dragsters and by weight conscious cafe racers. retail was $129.95

Mark McGrew
M3 Racing USA

kos · « **Reply #11 on:** October 20, 2009, 07:39:48 AM »

BTW...
If someone were to start making these type of swingarms...should make the "clubfoot" style. That is where on the left side of swingarm (when sitting on bike) the arm that comes from the rear splits right before the frame tube and attaches to the outside, as well as inside of the arm mounting point. This is the area of most load as the chain is puling on left side of arm much more that the right.

Just and idea.

I can provide drawings if needed. Perhaps someone has a pic of this type of arm? Or info on who made it?

Mark McGrew
M3 Racing USA

754 · « **Reply #12 on:** October 20, 2009, 08:14:13 AM »

Kos , KOSman made the arms you are talking about...

Chains are not a problem, 120 link will fit with a 48T at around 6 inches over.

I think the RC arms were built a bit so you can play around and try different lengths.. Swingarm usually looks cleaner to have only 1 axle position. Multiple shock mounts are handy.

I would say, set up a fixture and build exactly what folks want, as they will not all want the same..

kos · « **Reply #13 on:** October 20, 2009, 08:27:51 AM »

Sondro Kosman...he is the man!

I have to talk to him about rear spooled wheel for my Trackmaster SOHC 750 Hon so I will ask...perhaps he still has the jig?

Thanks for input "old timer"

KOS

MCRider · « **Reply #14 on:** October 20, 2009, 08:34:44 AM »

Quote from: kos on October 20, 2009, 08:27:51 AM

Sondro Kosman...he is the man!

I have to talk to him about rear spooled wheel for my Trackmaster SOHC 750 Hon so I will ask...perhaps he still has the jig?

Thanks for input "old timer"

KOS

I remember those swingarms. Kosman has the name for fine work. It would be neat if he still has the tooling or diagrams. That clubfoot idea is neat too, I've seen that on high perf dragsters. Requires a longer pivot bolt and another bushing I'd guess?

I have a front wheel for my HawkGT that was widened by kosman, piece of work. Of course all that stuff is a marvel to me. A hack saw and a vice are the extent of my machinist abilities.

754 · « **Reply #15 on:** October 20, 2009, 08:42:27 AM »

Usually if they are raced they use struts, on my 6 over arm, I just used pipe on the pivot end, bored it a bit to cleanup, then pressed in Aluminum bushings.. it never goes up and down.

MCRider · « **Reply #16 on:** October 20, 2009, 08:46:47 AM »

Quote from: 754 on October 20, 2009, 08:42:27 AM

Usually if they are raced they use struts, on my 6 over arm, I just used pipe on the pivot end, bored it a bit to cleanup, then pressed in Aluminum bushings.. it never goes up and down.

I see, a fixed postion would make it easy. (easier)

if I were to get one for me, it would have to go up and down.

ColinMc · « **Reply #17 on:** October 20, 2009, 08:51:40 AM »

I'd be very interested if at the most it cost 300....obviously less is better. I'd also love to just have the stock length but i'll take what I can get...Looks cool and keep us updated on what you find out.

NitroHunter · « **Reply #18 on:** October 20, 2009, 09:24:54 AM »

Back in the day, I had Kosman build one with the torsional brace for my SOHC. Had to modify his shock mounts so I could use my S&Ws, building struts was simple. No question it's a stout piece. It's the arm I have on my turbo bike.

bucky katt · « **Reply #19 on:** October 20, 2009, 03:20:50 PM »

i'd love to have one too, just no way in hell there will be any money for it for some time to come.

Bill/BentON Racing · « **Reply #20 on:** October 20, 2009, 03:28:15 PM »

Theres one on the bike in my avatar,used it w/needle bearing kit and 83 CB1100F shocks.It works pretty good.Have one more,probably use it on 1000cc kit bike.Bill

luhojs · « **Reply #21 on:** October 20, 2009, 11:40:19 PM »

I'm interested in the RC style swingarm. The original specs, as per the advert, appeal most to me.

Turbogrimace · « **Reply #22 on:** October 21, 2009, 05:20:38 AM »

So I've got two people interested? Are others interested in different versions of this? Perhaps one's with just a single axle position? Single shock position?

Thanks for all of the information guys.

Geeto67 · « **Reply #23 on:** October 21, 2009, 07:06:17 AM »

have you ever weighed an RC swingarm? I have one and that thing weighs a ton. If you were going to replicate it I would suggest you do it in aluminum instead (which means you need a thicker wall and an overall larger box section.

Turbogrimace · « **Reply #24 on:** October 21, 2009, 07:27:11 AM »

I havent weighed it, but it felt like it was decently lighter than a stock swingarm. Alum is an option though.

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Author Topic: Any interest in RC style swingarms? (Read 4011 times)