OzVMX Forum
Clubroom => Bike Talk => Topic started by: hagon_84 on May 30, 2013, 11:13:59 am
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contemplating building a pre 75 dirt tracker and wondering if there are any standard requirements running a disc rear end like a bully did back then but as i have bits and pieces to make it up out of late model honda rear wheel and brakes would this qualify legal i am still sticking to drum front brake though to be 75 legal
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bultaco astro disc rear 1975 so no
hagon rear sprocket disc mechanical only pre75
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Where does a Rokon 340 disc or Yankee 500 disc fit in?
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John some Flat tracker frames (Champion / Redline) ran those useless "sprocket as the disk rotor" brake thingos and crude standard type rear disk setups prior to 1975. Firko any help thanks.
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cheers for the insight jim well i think its stick to drums all round and save the dramas come race day
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On a Slider I don't think it makes a bit of difference if you've got a drum or disc brake on the rear, that is just my opinion, I could be wrong and regularly am.
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it dose if you want to compete in the pre75 class not so much in the pre90.remember in opens you ride in your class
my pre70 antig will have a xl250 side port motor so it is ok for the pre75 250 pre75 4 stroke and also the pre75 slider 250 or unlimited
my 500 bellini has a 500 yam in it so it is pre 78 it will have a disc on the back.
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My comment was performance based Jim but with the split between Classic & Post Classic classes there is def a grey area.
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yes if you are good you dont need brakes but to get on the track in a open meeting you need 2 working brakes based on the year you want to race,is to what type.just ask andrew pitt about that rule fastest bike at KON but only 1 brake so NO ride.
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There is a difference in the GCRs, re brakes, between Dirt Track, two brakes are required and Track ( Short or Longtrack ) only one brake is required, however, 500 Sliders on Track are forbidden brakes !!
Bloody hell !!, one's all ya need to pull up in the pits !!.
Foss
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Mom's specify machines and components built up to 1974 for pre 75. So if your components are made up from a bike 1974 or earlier it would be acceptable. A disc brake would however make the bike ineligable for the evo class.
Interestingly though is the frame and parts section for the classic slider class. There is no mention of brakes at all, only wheel sizes and suspension.
The motors are limited to 2 valve push rod motors, or two strokes made before Dec 1976.
I think the issue Jim raised about two brakes comes into play when you wish to race in modern events under the rules in section 20 of the Mom's.
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Had a 250 Maico hagon with the sprocket type mechanical disc . Lucky it was underpowered because the back brake couldn't stop a fly sliding on sandpaper.
Presently setting up a rear brake setup on my 77 godden centre-port wessie. Thinking of going USA flat tracker style and tucking the pedal in between the gearbox and oil pump with the gearbox lever then sitting quite away above it and slightly in front. Just looking for something neat as most LHS brake pedal look awkward and agricultural. Also hated the feel with a steel shoe. Thought about a handlebar clutch side second lever like the English grass trackers but setting up such a long cable would be a pain.
Rosco86
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You could certainly use a rear disc from a Yankee for Pre '75 as it was available from 1971. However you wouldn't want to, the caliper weighs a ton. From memory, both the caliper and master cylinder were 'off-the-shelf' items from Kelsey-Hayes.
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Yep, you're right, Sprint, about the GCRs for Classic DT, no mention of number of brakes required at all, at all.
And Hoony, for me TT Hagon, I fabbed a front engine plate mounted RHS brake pedal, cable to rear, didn't work well as ya had ta take ya foot off the swinging footrest to use it, no good, so just used the front,
Jim, when he owned it, put a handlebar rear brake on me Hagon, where the front should be, so I just use that on the all too rare occasions I ride it these days
BITD, On me Grasstracker used the LHS mounted rear brake just to slither into corners and the catch the slide with the engine, UNTIL Arne Hendricksen taught me to slow the bike by backing it in, it worked !!
With the two 500 Yams, chookie and Slider, I take all the idle off and use the engine comp as a bit of a brake.
I guess It's whatever works for you , Eh ?
Oh yeah, the Hagon mechanical rear discs were next to useless, especially after oiling ya chain, then they were useless.
Foss
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what about fugging t tt tttr fugg tttr triumph spit cough, ;D,rear disc wheel,nice spool hub??,they gotta be before 75?,had underslung m/cyclinder,T140E after comical f/r model?, :P
i look at the tip next i'm there ;D
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MICK
enough with the triumph slur or you wont get to ribe the yetman only work on it(not very often as its a triumph)
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ff ffuggg ;D, :P
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Mick, I had an 1971 OIF A65L about 15 years ago, loved the motor, strong as, didn't like the comicals and the rest of the bike, sold it to the late Darryl Hellyer up Newy way, I wonder what happened to it??
Foss
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Foss
thanks for the feedback might look at a cable and double perch setup on clutch side as an alternative. Finding it a pain in the arse, very little room around the rear axle area on the godden. Was setup as a long tracker and converting back to short circuit hasn't been fun. Spend heaps of time and money setting up new braked wheels that only basically get used at scrutineering and in the pits. Oh well back to the drawing board.
Rosco
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The problem with running a disc in pre 75 dirt track is that the motocross rules are used . It's another example of a rulebook that needs a bit of a revamp. My upcoming '74 Shell 750 Yamaha has an Airheart rear disc and I reckon you should get away with single spot Grimeca, Airheart, Kelsey-Hayes and Girling/Lockheed which were all available prior to '75.
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that was my thoughts firko that i would be ok if its pre75 but like u said they run off motocross rules for braking simplest thing i can come up with is drum front n rear and use in the pits only ;D
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84, I use a early DT 175 rear hub with a 19" rim in me Sandracer, light as plus sprockets are easily available, slotted brake plate lines up with the lower shock mount bolt.
Foss