'75 Six Day

[brian kirby]

quote:Originally posted by Dwight Rudder

Brian, You can't use a 1975 frame for Sportsman Vintage. It is illegal. It is more than just a swingarm change. It is an entirely differnt frame design.  So just getting the travel right is not legal. It will be still in the Post Vintage Historic Class.  If you want to build a 100/6D that is not the problem. It is the frame is a long travel frame.  I am surprise you weren't protested with your other bike with the modified swingarm. Rules state you must mount the shock in the middle hole on the CMF frame swingarm . Yours is moved way forward of that.
Just say'n,
Dwight

Dwight.

First, I am aware the '75 is not legal for AHRMA vintage, where did I ever say I was going to race it in an AHRMA event? This bike will be for the Marty Tripes 100  vintage class which allows any kind of rear shock configuration limited to 7" of travel.

Second, the RULES never said anything about what place to mount the shocks, it was in the "cheat sheet" Dave Boydston put together with the shaft travel lengths for different bikes. If you go to the "member resources" page on the AHRMA website it is at the bottom of the page. On the Penton the visible shock travel had a note that said "middle hole, always check". It was NEVER in the rules.

On my other bike, it has 4" travel (a little less actually). I pointed out the modified shock mount at tech the first time I took it to James Smith so he would specifically measure it differently than a stock CMF frame. My bike is no different than putting a Mag swingarm on an older Husky or older Maicos with frames hacked up to do the "Wheelsmith" mod like the 74.5s. It is completely legal and if someone wants to protest the bike, fine by me, they will lose their protest deposit.

Brian

[Larry Perkins]

Dwight "Half Cocked" Rudder.  Just teasing Dwight.  Brian is right on this one but it brings up the point once again of AHRMA's analness on some things like a 1/4 inch too much travel and looking the other way on engine mods and pipes that could never have existed in "The Day".  AHRMA is the NASCAR of Vintage motorcycling as far as rules go.

Larry P

[Dwight Rudder]

Brian " Second, the RULES never said anything about what place to mount the shocks, it was in the "cheat sheet" Dave Boydston put together with the shaft travel lengths for different bikes. If you go to the "member resources" page on the AHRMA website it is at the bottom of the page. On the Penton the visible shock travel had a note that said "middle hole, always check". It was NEVER in the rules."

I knew I had read it somewhere as it has been brought up before. Thanks.  If you plan on racing it only in the Marty Tripes 100 series that would be no problem. Only would be if raced in AHRMA Vintage 100 or any other Vintage class. You should have said so to begin with. As for your other bike,  I might have to see that measurement myself. LOL. Remember on a setup like that 3/4 of the bumper is counted as travel. Not just the 1/2 bumper as on the stock bike. Besides. I don't think I have ever seen a swingarm like that used back in the day. The other swingarms you mentioned were stock but on another frame. So, What was your point on modifying it ? What were you trying to accomplish ?  I have seen others go to longer travel shocks for more control but move the mounting to the rearward hole so the travel at rear wheel would be legal. But you would have to shorten the shock travel to be legal ? Just wondering. Maybe something I need to do myself.

[Dwight Rudder]

quote:Originally posted by Larry Perkins

Dwight "Half Cocked" Rudder.  Just teasing Dwight.  Brian is right on this one but it brings up the point once again of AHRMA's analness on some things like a 1/4 inch too much travel and looking the other way on engine mods and pipes that could never have existed in "The Day".  AHRMA is the NASCAR of Vintage motorcycling as far as rules go.

Larry P

But that is the point. AHRMA is right in trying to preserve the vintage racing and not turning it into a competition of modifying all the old bikes into more modern bikes. I just don't understand what some mods are trying to accomplish. Others we can obviously see and they are bending the rules to the limit and then some.
Dwight

[G Ellis]

I think AHRMA should have a rule of only one brand of bike allowed.  This way even playing field for all involved.  This would be the right thing to do, in this political correct  world we live in today. Then it would come down to the rider.  My vote PENTON would to be the brand.  later Gary

[brian kirby]

quote:Besides. I don't think I have ever seen a swingarm like that used back in the day. The other swingarms you mentioned were stock but on another frame. So, What was your point on modifying it ? What were you trying to accomplish ?

I didnt modify it, the swingarm was modified by the original owner "back in the day" in SoCal. Paul Johnstone bought the bike from the original owner, then sold it to me. I have not changed a single thing on the bike, it is exactly as the original owner raced it in SoCal in '72. I have no idea what the original owner's intent was modifying the lower mount, but I am not going to change it since its the textbook definition of a "period correct" mod.

James has a computer at tech with a program he enters the measurements from swingarm pivot, top and bottom shock mounts and rear axle, it then tells him how much visible shaft travel is allowed on custom mount setups. The shocks I'm running measure out at about 3.9" of travel when mounted on my bike, James did it himself. Just for my own curiosity, since I've never actually done it, I am going to take the spring off a shock and do the "actual travel" measurement to see what it has.

Brian

[Lloyd Boland]

Brian, interested about the program. Is it available somewhere or is it a program he wrote?  I haven't raced an AHRMA race for several years, but I remember they had some kind of conversion chart for many of the standard bikes and modifications.  But if you had some sort of custom modification, the chart did not work.  I remember riding for Mid-Valley CZ in 1973-4, we cut the frame, move both the upper and lower mounts, etc.  These mods were done in 1973-4 time frame.  No way could the charts AHRMA had be able to accurately give me a shock travel distance to equate for wheel travel because of these mods.  They made me remove the springs and did an actual measurement at Tulare.  Again, this was several years ago, maybe 10 or more.

I haven't checked the rule book lately, but I think it is still WHEEL or AXLE travel, not shock travel.

Good luck with the 100.

Lloyd

[brian kirby]

Lloyd,

I'm not sure where the program came from, but it is a simple triangulation program, all you do is plug in the distances from the various points and it calculates the theoretical travel at the rear axle. James' sister is a programmer, so she might have written it. The have it specifically for custom configurations that dont fit the chart so they dont have to make people take their springs off like they used to. James is a smart guy, you are not going to slip anything by him at tech. You are right though, if there is any further doubt, actual travel as measured at the rear axle is the final say.

Brian

[brian kirby]

AS a side note, I would guess my setup would be close to a Falta CZ, Mag Husky, or 74.5 Maico. In the chart from AHRMA the Falta CZ and Mag are listed as 2 3/4" and Maico is 2 1/2", mine shocks measure 2 3/8".

Brian

[gooddirt]

If I'am not mistaken bill cappel ran his 1975 and won the national ahrma series 125 classic class, or at least he ran it a year or two.

[pakala]

Baby Brian,
Here's what you missed at Diamond Dons. Fun Fun Fun!
 http://www.youtube.com/watch?v=FwCdTF5ych8&feature=youtu.be
    See ya next trip! Pablo

[Dwight Rudder]

[/quote] I didnt modify it, the swingarm was modified by the original owner "back in the day" in SoCal. Paul Johnstone bought the bike from the original owner, then sold it to me. I have not changed a single thing on the bike, it is exactly as the original owner raced it in SoCal in '72. Brian
[/quote]

I can promise that he didn't race the bike that way back in 1972.  Maybe in 1975-76. Nobody changed lower mounts till 1975

[Larry Perkins]

Dwight,

Nobody is a lot of people.  I had a older Berkshire in early 1974 that we forwarded mounted the shocks on but bent the swingarm from no gussets and went back stock.  We did it in about April after getting in one of the 74.5 model Pentons which had forward mount and laydown stock from the factory.

Larry P

[firstturn]

I am glad to know someone else bent a swingarm back then[].

Ron Carbaugh

[Larry Perkins]

Ron,

My Mother didn't call me "The Flying Monkey" for nothing.

Larry P