classic motorcycle forum
Motorcycle Discussions => British Bikes => Topic started by: JAP on January 02, 2012, 09:08:55 PM
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im from UK warwickshire and im building a 1920s style motorcycle with a 350cc jap engine any tips would be great.
i need a clutch and a gear box.
PS i know the welding needs cleaning up a bit :)
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the welding needs cleaning up a bit :)
umm....indeed! :-\
Look at as many pictures of 1920ies bikes as you can find on the web to get the style right and make your needs known in the autojumble section! Good luck with your project!
Cheers
Andy
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be sure you dont kill your self , the frame does not look to safe to me
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be sure you dont kill your self , the frame does not look to safe to me
I agree.
I did not want to cool enthusiasm in a very worthwhile project, so I did not post my concerns about the welding.
There looks to be almost no penetration on the "welds". "Tidying" them up will not cure that. Also the welds (frame?) ought to be annealed to remove brittleness.
Jim.
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Yeah, me too, I'm afraid. While we're on an enthusiasm-killing rant, the fork links probably need to be thicker. Even quite light-weight bikes had thick steel pressings here, and most had forgings.
Incidentally what steel tubing are you using?
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Your honesty is valued, i did think that the fork links were a bit thin.
As for the welding i have taken it back with a grinder and will heat the joints before re welding them.
Its so kind of you guys to help out like this, i didnt think i would get an answer.
The bolts i will be using for the fork links are 12mm thick, is that OK? i have put bronze bushes were the bolts will go through.
Today i have made a bracket for the magnito to go just under the carb.
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I've always used EN8 or EN16 steel with threaded ends here rather than bolts, but I suppose it really depends how you've designed it. Four long pivots gives strength and ridigity as you don't want either side of the fork trying to move independantly of the other.
It's an MOT test point (the amount of shake at the pivot/bush area) so they need to be machined/reamed exactly for a nice sliding fit whatever you use.
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wheres the dampening on the forks , might be like a pogo stick
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could you explain DAMPENING ? have you a photo. and how thick does the fork links have to be?
sorry about all the questions.
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wheres the dampening on the forks , might be like a pogo stick
Damping on girder forks was quite a late invention - girder forks WERE pogo sticks for many decades. Not many early teles had any real damping either...
A simple hydraulic steering damper adapted to the girder fork action gives fork damping decades beyond their design...
Think that frame should be professionally welded....
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Damping on girder forks was quite a late invention ? how late ? how early are you talking , do you think it was a good idea
A simple hydraulic steering damper adapted ? will not work you need to take a good look at how they work
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A simple hydraulic steering damper adapted ? will not work you need to take a good look at how they work
I've seen them fitted and working.
Damping the basic girder fork action, that is.
Not acting as a steering damper.
Damping on girder forks was quite a late invention ? how late ? how early are you talking , do you think it was a good idea
You don't see too many 1920s bikes with any form of (friction) damping on the girder forks. And they all (?) survived.
Hydraulic damping didn't appear until the 1940s (?).
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I've seen them fitted and working.......where ? my understanding of this type of unit is that it works in both directions and would only make the forks ridigid , when what you need to do is control the rebound this is the job of the friction dampner and they work well if set up correctly . if youve ever made a tank out of a cotton real , a candle , elastic band and a touth pick you will understand how this system works , the 20s bikes comment i dont understand sorry , can you show me a pic of your system in use i may try it myself i have many girder fork machines all with friction dampening of differant designs .
http://s1205.photobucket.com/albums/bb429/1wetdog/?action=view¤t=myoldbikes012.jpg
here are some extra fitted to my sunbeam bently and drapper
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I wouldn't worry about welding or damping etc, because this bike will never be registered. It's obviously a showpiece for his lounge.
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i am inclinded to agree but still some thing to talk about and interesting to hear other peoples views , i am about to learn somthing new maybe
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I wouldn't worry about welding or damping etc, because this bike will never be registered. It's obviously a showpiece for his lounge.
why would it not be registered, what are the rules ???? if i get it welded by a professional i cant see why not.
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I've seen them fitted and working.......where ? my understanding of this type of unit is that it works in both directions and would only make the forks ridigid ,
Suggest you have a look at some of the little steering dampers around then - far from being 'rigid' they have gentle damping, in both directions like you say, adjustable stronger or weaker. Fitted to the girder fork action, they provide a modicum of hydraulic damping, adjustable with a click.
If they'd been available in the 1920s, would have sold gaziilions...
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they are adjustable but resist sharp fast movment , please show me the application you have seen i am very interested
have this sent via a dealer it explains what i can not
Steering dampers can be found on many modern sportbikes and all race bikes, . A steering damper provides a resistive force against the direction of movement, giving controlled compression and rebound. Dampers are velocity dependent so the faster the spring moves (like when you hit a bump), the more resistance the damper provides
i read that as not suited to girder fork application as they are always hitting bumps and the steering dampner would try and control the spring movment on compresion which is useless , what do you think
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Can't show a pic don't have one. They arrived fitted to forks at a rally, so despite doubts they work, haven't tried them to verify. Fitted vertically, bolted one end to yokes and other end to fork blades - ie one end to the moving bit and t'other to the solid fixed bit.
P.S. Modern forks have both compression and rebound damping, usually adjustable separately. Even friction dampers have a measure of compression damping....
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I'm confused; Wetdog's talking about a steering damper, while R's talking about a suspension damper apparently fitted to girder forks. Nothing new about these as Indians had them on the 1946 models onwards.
Then again, if the subject is hydraulic steering dampers, then there's no reason why one of those little telescopic after-market dampers couldn't be used on girders either.
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then there's no reason why one of those little telescopic after-market dampers couldn't be used on girders either.
That is precisely what we are talking about.
Apparently quite effective...
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Fitted vertically, bolted one end to yokes and other end to fork blades - ie one end to the moving bit and t'other to the solid fixed bit.
This is the confusing bit as it describes a suspension damper.
If it was the little telescopic steering damper, it would be horizontal and fixed to the girders at one end and the frame the other.
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sorry rex now im confused R is talking about a steering dampner
"A simple hydraulic steering damper adapted to the girder fork" quote
a suspention dampner is a differant thing and i agree these can be used , and i have also seen springer fork set ups now being made with complette skok absurbers fitted
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Then he must be confused too! A steering damper can't go from the yokes to the blades as it all moves together as the wheel is "steered".
Even the original girder steering friction damper connected the lower yoke to the bike's frame via a couple of friction discs.
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by now the Original Poster must be thoroughly confused, too...
so please R, Rex, wetdog, back to the topic and try to answer OP's latest question:
why would it not be registered, what are the rules ???? if i get it welded by a professional i cant see why not.
I myself cannot suggest anything here because I am as unfamiliar as OP with the registration rules for self-constructed vehicles in England
Cheers
Andy
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It's not a case of how good the welding is, more a case of the pain in the ar*e that going through the reg process can be.
Back in the days of crappy choppers they used to use the V5 from a moped or whatever, and end up with a 650 BSA engined effort registered as a Honda 50, but thankfully the DVLA are wise to that.
The OP will need to go on the DVLA website where the long-winded process is explained. Maybe that's why someone suggested this will end up as an ornament..... ;)
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cheers lads a answer at last ;D
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rex read the post from page one not 2 and all will become clear i hope
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The angle and length difference of the top and bottom fork links is very important and should be matched to the steering head rake. As the suspension moves the front wheel trail angle must be controlled. Any error in the design could effect handling a lot, speed wabble (tank slappers) is no fun. Good luck with it and I hope it works out.