Penton Owners Group

Any of you Pentonites interested in aluminum aftermarket swing arms?

My name is Dom Dominik and we at: //www.VMXpert.com
are getting ready to develop our next group of swingarm products.
I'm soliciting your input as to what Penton models would be candidates for aluminum swingarms.    Also, what swingarms are common to several models ... if any.
Last ... need POG expert contacts to answer questions.

Thanks

Dom Dominik
VMXpert Performance Products
//www.vmxpert.com
Longmont, Colorado

Dom

I would be interested in one for my 78 KTM MC400 ???

 

Dom, would an aftermarket swingarm on a '74 250 Penton run afoul of AHRMA rules?

Glenn

 

Silver paint would cover any infraction of the rules---HE HE.  Also,at VMD there was a Penton already running in the races with a trick looking alum. swingarm.

Edited by - metalkfab on 07/25/2002  5:50:54 PM

Hi Dom , I saw that swingarm, if that is yours, congradulations! Very nicely done. I am going to butcher this mans name, because I only recently started following vintage, it was Ballentine or Vallentine, sorry man. He definitely got my award for trickest Penton.  Dom, give us some details, like type of bearings, type of chain adjusters, I noticed it had only one position for shock placement. How much $$'s.  Make mine for a "75" 400. Thanks alot, Bob.

 

Hi Glenn, how's it going. Remember that DG and some others made after- market swingarms for the earliest el'snores & RM's. So if they use them, everyone can. Are you almost ready to fire it up? good luck, Bob.
 p.s. At first it seemed odd, on a Penton? You instantly lose the classic style.

Edited by - rob w on 07/25/2002  9:30:03 PM

Monty, Glenn, metalkfab, Rob
Thanks for your interest and quick replies.

AHRMA Eligibility .... both "DG" and "Crossup" had aluminum swing arms "pre 74" .... I have photos.

Rob ... thanks for the compliment  ... we spent 6 months in design and test.   Also, please read through the web site pages ... there are options for bearing materials from hard aircraft quality nylon to needle bearings.

As for the shock mount it was designed to allow for custom location.   Shock mount location flexibility was one of the "must have" design features for our swingarm products.

Currently we do not have a design to incorporate multiple holes along the swingarm.    However is the interest and commitment ($$$$) are there VMXpert is ready.

Again thanks ... I hope this info helps

TBC (to be continued)

Dom
VMXpert PP

Dom

Dom, my next project after firing up my '72 125 is a '74 250.  I'm looking for a swingarm for it, so maybe there's some of the demand you're looking for.  Please keep us Poggers posted on how you're going to proceed.  Thanks.  Glenn

 

Dom,
 can you supply replacement swing arm bearings for the orignal 72-74 100,125
Pentons?
 i know at least two in the group now are in need and none seem to be had in the states
John Durrill

 

I'd be interested in a couple for 72-74 Penton 125 and a 75 Mint 400 and a 76 Six Day 125 w/KTM motor.
Donny

OUCWBOY

...been watching this site for two days .... Your guys are obsessed!

.... I'll try to round up some 72 – 74 frames for measurements ... any volunteers?    I'll pay postage both ways.

Thanks

Dom


Dom

HI DOM
    There is also interest over here in the UK please keep me posted albeit for KTM's from early 70's
          MAX.

 

Hi Dom!
There is another person living in this house who calls it a sickness! I call it fun. Where are you located. I'm in Southern California so there may be someone closer. I would be willing to send a frame to you, I have about 3 or 4 not in use.
Donny

Dom,
boy do I feel stupid. I see that you are in CO.
Donny

Dom,

I got your phone message and I will call you back a little later today after your morning thing is done.  I have a NOS 72 frame and an NOS 74 frame.  These should help you get acurate measurements.

 

Does anyone have an NOS swingarm bushing  for the 72-74 100 ,125 Pentons that could be sent to Dom?
 he can produce a replacement for us.
 I will buy 2 sets of the replacements. anyone else?
 Larry would you have 1 you could loan him long enough for the measurements to be made?
John & Peter


 

I spoke with Dom at length on the phone last night and I am sending him 4 frames and a swingarm bushing so that his tech work can begin.  I think you guys will see cool things come from this guy.  Let's all remember that when his product comes up for sale.  He is definitely doing this as a labor of love and won't get rich off it.  Just remember love only goes so far.  Anyway this should fix him up with all the product he needs to put the calipers to it.

 

Thanks Larry.

 

Lets not forget the the 76 and 77 year bikes, Word champion MX 250 and 400 MC-5s.
Thanks, Dan.

Posting 07/2002
Yucaipa CA.
Age 49, maintenance mechanic, two 77 Pentons, 250,400 MC-5s.

Dom has located some local guys with frames so that will cover that part without shipping.  I am sending bushings to him today so he can work on that part.  His plan is to also do 76 and 77 bikes but will do the 73 style and 74 style first because of more demand.  I too will be a player on both he says he will do this in stages.  From what I have seen and heard from him it will be worth the wait.

 

Do the MC5s! help Pentons retain AHRMA dominance!

Chilly Pepper
Historic 500 nat'l champ

 

I find it strange that POG members would even consider putting a foregn ( aluminum ) swingarm on a Vintage Penton. It would ruin the collectability of the bike. Save the after market trick parts for modern bikes. Leave our Vintage bikes vintage.
IMO
Dwight

7 time ISDT / E medalist
7 time National Enduro Class Champion.

Quotequote:
I find it strange that POG members would even consider putting a foregn ( aluminum ) swingarm on a Vintage Penton. It would ruin the collectability of the bike. Save the after market trick parts for modern bikes. Leave our Vintage bikes vintage.
IMO
Dwight

7 time ISDT / E medalist
7 time National Enduro Class Champion.

 

Collectability and AHRMA racing are two different animals.  A early 1972 Jackpiner came with an Amal carb but if I was going to ride or race one I would not be caught dead with it.  In racing trick has always been a path some have followed and AHRMA and the spirit of winning insures that will continue.  I agree with Dwight if you want to keep the $$ value in collecting then original is where it is at.  If you want faster and lighter for the sake of victories then trick is where it is at.  This is a good example of two different trains of thought that exist in the POG and Vintage.

 

Larry, Dwight,
There is also a middle ground between the two ends of the spectrum, and it is actually fairly wide.  AHRMA MX is there "to preserve, use and show the machines.... preserve the feel, sight and sound..."  (Dick Mann's words in AHRMA rulebook).
My middle ground is stock major parts and modifications commonly available in the era - a little (not much) tougher than the rulebook standard, but that's where I draw the line.  Hence I have Ceriani and CZ forks and hubs (both available in '65) on my Premier bikes. My Buls and Pentons are pretty much bone stock (but tuned).  I try to keep the bikes and my outward apppearance "vintage", because I really love the old bikes, the racing, and the crowd that does this stuff!
Point is, you can be competitive and live within the spirit of the rules, primarily because about 80% is rider anyway.
My humble opinion.
dave

 

I would honestly like to know what the real weight difference in aluminum and chrome moly swingarms would be. I would bet there wouldn't be enough difference to count. I don't believe too many folks used aluminum swingarms in 1974 so I also feel this goes against the spirit of things. If you want trick go fast parts that weren't used in 1974 , then I don't think that Vintage racing is right for you. I don't think an aluminum swingarm will make any diffence in who will win. Now if you want to make a replica of a swingarm that was used then to replace a damaged one I say GREAT.
IMO,
Dwight

7 time ISDT / E medalist
7 time National Enduro Class Champion.

Dwight,
I'm strongly with you in spirit. I raced in CA, TX and FL in the early seventies and there were a very few aluminum swing arms on a scant few bikes, but I don't remember seeing any on Pentons ( I could be wrong - memory is the second thing to go).
Your statement that "If you want trick go fast parts that weren't used in 1974 , then I don't think that Vintage racing is right for you " - I agree with you 100%!
AHRMA has made it legal for some (since some bikes did, in fact need and use the aluminum awing arm - thus it is "of the era"),  but this has made it legal for all - not necessarily wrong - just a lot more than we had then.  
I'll still stand by the statement that the rider makes all the difference.  You could ride a tricycle and beat me Dwight.  I guess it comes down to the level of tradition and history we want to re-live and recreate.  
An unabashed traditionalist,
dave

 

I basically agree with you guys, but not completely.  In forward mount position 74 and 75 Pentons will eventually bend the swingarm and I believe the extra rigidity of aluminum might help this.  I love Post-Vintage even more than Vintage and my MC 5 back then and now can and will bend a swingarm.  Granted I am the guy that got his pic in Cycle News last year at the Berwick National 15 feet off the ground doubling 30 feet on the back straight but that is PostVintage and there were four or five big doubles at I think Portland also.  I love the air but a better swingarm would help that bike and there were alot of them by 77.  I won both those Nationals because I doubled and the other riders did not.  I guess then the rider part comes in but if I broke my swingarm I would be screwed.  The rider can't go too fast with the bike in two pieces.  I can vouch for that from personal experience.  I did break a footpeg at Portland on the 400 and had to limp around the second moto like an old lady.  Therefore I now use stainless steel footpegs that are wide like modern pegs.  

Anyway trick is often mental too and I believe in the principle that sooner or later the that wins is the one that thinks he can.

One place I will not compromise to Vintage standards is in safety.  In 74 there were no body shells, neck rolls, high tech boots, titanium knee braces, and lightweight full coverage helmets.  You won't see me race without them though.  If I spill I don't have the body I had in 74 so I want the protection of 2002.

Isn't debate fun?  Next.

 

Hummmmmmm.........Larry, somehow I don't remember Doubles back in 1974.
HEHEHE
Dwight

7 time ISDT / E medalist
7 time National Enduro Class Champion.

Dwight,

I was talking about my Post Vintage Historic bike which was through 1977.  Doubles in 74?  They were just showing up.  Seems like I remember a small one at the Second Superbowl of Motocross and I think that was 74.  My memory is foggy from then though because I had a hefty concussion that year from a trip over the bars.  What was more prominent on the National Circuit from 73 to 75 was the BIG jump.  Mid-Ohio had one that was like jumping off a house and the Peristyle in L.A. Coliseum was like falling into the abyss as was the Gravity Cavity at Lake Whitney Texas.  I broke a swingarm at Mid-Ohio in 125 practice but I can't remember when.  Somewhere between 73 and 75 I think.  Mickey Boone flew over that jump and you could feel the ground shake when Tripes landed off of it.  

Trick swingarm might have been good then but more travel is what was needed and of course just like History it came and came fast.

 

The main reason for using aluminum, to make a swingarm is not solely to lower the weight, but that you can use a larger tube and thicker wall material to achieve a much stronger, more rigid part at the same or lesser weight. The only thing about Dom's swingarms that may not look the era, is the finish (polished aluminum). Change that to some silver/grey paint and no one on the side lines is going to notice. In fact, for a 74 or 75 machine (sportsman class) I think they look very unconspicuous. Now if you were to install one on a 72, that might look a little out of place. What I think is wrong with some of the vintage classes, is that they are letting 76 & 77 bikes run with shock limiters in vintage sportsman. AS for the tracks today, COME ON!, why are people bitching about a jump here and there? I started racing in 71, and there were alot more jumps, and bigger jumps, and big whoops than these lame tracks I'm seeing today. I know we're all getting older, but I thought this was suppose to be moto-cross. Where are the good tracks? I don't see them. Thank you. Bob.

 

Hi Larry,
Good points and discussion - the "debate" is one of the best parts of our vintage disease (except when it gets personal).
Here's some more thoughts:
I agree that the forward mounts on many of the ~75-76 bikes need more rigidity for big air in the PV classes.  Unfortunately AHRMA let the camel's nose under the tent in the Vintage classes with some of the like design long travel 75-76 bikes (limited to 4") and moved up aftermarket swingarms on the pre-75s.  I tech them and keep it to 4" but you wouldn't believe some of the stuff guys bring to tech.  At Hollister two years ago, a guy brought a 350 Honda with a 5" extension welded to the swingarm (I saw some of those "in the day"  too.  I made a mistake safety-wise and let him ride (he swore he'd raced it previously).  It folded gracefully in practice with no injuries.  As you remember, even back in the vintage day we used to overtax the bikes and break not only swingarms, but steering heads,  frames and shocks. Remember the famous picture of Doug Grant "wheelbarrowing" his Stormer forks and wheel over the finish line at Indian Dunes?  Point is, reliability vs weight savings has always been an issue in MX bike construction and racing.  How hard you could push a bike has always been part of the equation.
Personal Safety.  Riding gear has come a LONG way.  Any compromise of safety has to be done with full recognition of the tradeoffs.  With the exception of full face helmets, almost all the high tech items you mention can be worn underneath vintage leathers and jerseys (I do this).  Several top quality boots can purchased in all black (or close to it).   I choose to race vintage MX with an open face Shoei with Scotts face protector, but I race vintage Flattrack/TT with a full face.
Tracks:  Lots of variety in opinions  here.  I raced (amateur) all over the country in the '70s and early '80s, and I've raced AHRMA nationally (although primarily in the west) since 1996.  Regarding "Vintage" tracks, we tend to have a lot more man made jumps now than then, but we also tend to have a lot less whoops and rough stuff.  If any of you disagree about the whoops, go get out your copy of "On Any Sunday", most of the MX stuff was filmed in 69-70.  I have to watch it now and then to remind myself how rough it was...  That having been said, realize that in addition to vintage tracks of the '70s and Post Vintage of the '80s,  AHRMA is trying to replicate the tracks of the '60s which were more rough scrambles, but often called MX after ~65.  A heathly mix of tracks is what I really appreciate.  
BTW, for any of you in the west who want to race a real '70s style MX track - try Honey Lake!  Larry Wosick runs it and it'll take you back in time.  I had more/different sore muscles after racing there... Dick Mann told me those were my "motocross muscles!."
Enough for now!
regards, dave

 

Dom, I would be intrested in an aluminum swing arm for my 75 mint 400 penton.      mark.

mark s seals

dom, thanks for returning my email. A 1976 swingarm will fit the 75 frame. Please keep me posted on progress of your product. I would be verry interested in seeing a picture of a finished swingarm, also how much i could get one for.  Thanks mark.

mark s seals

VMXpert...so, when are the '73-75 mx swingarms available?
No word since August, any update?

CR

 

And the swing arm bushing replacements for the 72-74 cmf 100,125,175 frames?
John

 

I might be interested in a swingarm for a 75 250 Penton.  I agree with Dwight on originality.  The way they were then, they should be now (including tracks): however, if a bike has a deficiency that is going to relegate it back to the shed, I am willing to fudge.  Maybe someone could build an original swingarm with reinforcement like the guys are using for AHRMA motocross now.

 

so, how are the swingarms coming?

 

Takes time guys, Dom is an engineer at one of the biggest Aerospace engineering companies in Colorado, one of his biggest challenges is to balance his enormous responsibilities at his job, yet find time for one of his biggest dreams, I have had the opportunity to both meet him and watch him cheer me on at the Nationals, and he has been made aware of what is happening, I believe he has made a commitment, one thing at at time....please!!!

 

Has anyone heard anything on the new swing arms or the replacement bushing from Dom?
 We have sent three e-mails to them in the last 3 months and no response.
 I would like to replace mine befor the RR and we are building a 72 Six days that needs them now.
John & Peter

 

I had contact with Dom some months ago and was under the impression he was going to send me the parts to weld together. We had discussed working together because I am making arms for Hugh's Bulls. I had thought about going into the swingarm business but the tooling cost VS projected short term sales looked like too thin for my small business. I would like to be able to make vintage parts for Penton but I am not at the point yet where I can't afford to do much without someone ordering several pieces of a single item. The vintage market is interesting in that todays cost for prototype parts are way more that the cost of old, used, mass produced parts. Who wants to buy $500.00 swingarms? not me either.

 

Update on the replacement bushings for the 72-74 cmf 100 , 125, 175 swing arms.
Dom just sent me an E-mail. the Day job     has slowed him don a bit but he is willing to make up the bushings.
 Will let you know when I get the first two sets.
 This is great news. It would take a month in the garage for me to come up with something that might work chuckle chuckle.
 the might being a pivotal part of that statement :>)))
John & Peter

 

Did anything ever happen with Dom making these swingarms?

Chuck

Spencer Ballentine has been racing AHRMA for years with a trick aluminum fabricated swingarm. I tried to get the guy who built it for him to build me one, but I finally chickened out because of price.

Teddy

How bad was it?

Chuck

Has anyone tried using/modifying the KTM aluminum swingarm from the '80-'81 (I believe?) KTMs to replace the chromemolly swingarm on the '76-'79 MC5s? The swingarm shock mount is quite a bit further forward and arm is about an inch longer.

I have a late KTM alloy swingarm and had tinkered with the idea of modifying it for the MC5. But if you loft it in one hand against the steel one in the other, they seem to weigh about the same. So if no weight advantage, then rigidity and longer wheelbase? Not sure it's worth the effort.

Mac

I did some serious looking into roller bearing conversions for my 73-125 6 Days. Even went to a couple local bearing distributors.

After finding that the wheelbase on the EXCELLENT handling Penton was 4 inches longer than a 74 YZ 125 and a couple longer than an Elsinore, I concluded if it works dont fix it.

The cahin even stays on those two sharp pointy things every moto.

CHAIN[B)]

You mean you don't end up with a thrownchain???;)