Manky Monkey Motors

Right then, Girders eh, ok. Let me start by saying that this is not going to be a blueprint for Girder making, sure, i could give you sizes, dimensions and angles, and off you`d go and make a set, and yes they`d fit and work but there are so many varients possible that i`ll leave it to you to sort the details. I will however, hopefully at least, show you how to go about making a set.
I don`t actualy have a use for a set yet, but i have got half an idea for them, but first lets see if i can make some!
First job then is to make the main leg assembly.
I`ve pre-drilled a pilot hole near the end of my tube and now i`m ready with the holesaw to cut the tube.

The holesaw is the same diameter as my tube and will cut a nice mitre in the end of it.

This is to allow me to slot a shorter piece of tube in the ends and will give a nice joint for me to weld up.

with the ends of the 2 long tubes notched, i cut an 8" length of the same diameter tube and tack welded it squarely onto the longer bits.
Straightforward job, use a square to make sure the tubes meet at right angles and leave a 1/4" hangover at each end of the short tube, this will give you something to weld to later  ;)

And here`s how it looks. Do i need to mention that when your tacking this together, do it on a flat level surface?

Now its out with the bender and some more tube. At this point you`ll need to know what length headstock you`ll be fitting your finished girder on to because this will affect the position of the bend. How much of a bend you put in is up to you, the longer the Girder, the taller you can have the bend, its all about looks.

A few pumps on the handle .......

then try it in place. When your happy with what you have, make a second one.

Then lay the legs back on your flat surface and position the back leg so that you can mark the taper you need to cut in order to weld the legs together.

you`ll need to mark both top and bottom tapers on the rear leg.

with the tapers cut, lay the rear leg onto the front one and after making sure it sits squarely, tack weld it on. (yes mine is a little off in the photo, i couldn`t hold it all square and take the picture  ;D)
Do the same again with the second rear leg and use a spirit level across them to ensure both legs sit the same height.

Now you can weld everything up fully.
After my initial full weld i layed a second bead on as a filler, this means i can flatten the second weld off and produce a solid looking assembly.

The filler bead is not structual so i can grind it down to produce a flush `gusset`, purely asthetical but helps give a `chunky` look to the girder.

then its time to put in the lower cosstube. Mark down from the centre of your toptube, the length of your headstock, then knock up a couple of support brackets, these will be welded to the front and rear forks.

Before i cut the brackets out, i cut out another inch diameter hole on the centre line of the bracket, 6mm in from the front leg. Again, the 6mm gap will allow you to weld the bracket in.

The brackets are then cut to shape and welded between the legs, then another 8" long piece of tube is inserted through the holes, leaving a 6mm overhang on the outside edges and welded in place.

and apart from a bit more tidying up....thats them...for now
Next i`ll make up the link rods and something to attach them to.

Thy look the job will follow this with intrest

The girders are held to the yokes with links, basic dogbone shapes made up with more of the same tube will do, although they can be made fom flat plate.
Two short bits and a longer bit,will be mitred then welded.

And when finished they will sit like this.....

you need 4 of these in total, 2 for the top yoke and two for the bottom, so i`ll pick this thread up again when i`ve done the other 3

Some WW2, BSA M20 forks which might assist in your deliberations Mr. T, and they do in fact use flat "dogbone" links, Morrag

me I love girders  ;D ;D ;D

I love Girders too

Made a few sets of these and they require great accuracy

A handy hint when making girders is to self template.... Make one side and then use that with shafts fitted to make an identical one for the other side as 1/4mm out at the links could transpose it to a large problem at the wheel end!

Great thread,as ive been interested in making some myself.Just a couple of questions. A. Does the tubing need to be made from a special material,and whats the size of the tube diameter and the wall thickness.
B. How do they feel,as opposed to normal forks.Could you still crank your bike right over and power out of a long bend?

You have very obviously never ridden a machine equiped with old style 'Girders', but the answer is NO.......unless you have some kind of death wish. They are ok for 'Show' but don't even come close to a modern, telescopic,fork,in performance. I am of course excluding the modern, 'Beamer versions of the type!which I have never tried, Morrag

Morrag is right for sports/racing bikes but for Trikes and Custom bikes you cant beat em.

The original custom girders back in the 60's and 70's where often made from bent solid bar and had really crude links that flexed.

This got them a bad reputation but if well designed and built they work great. Because the headstock and fork legs don't have to run on the same plane you can set your trail and have an easy to ride machine with a lunatic rake on it   ;D

The last trike I made handled better than any other that I have made or ridden, The problem is they have to be made to fit each machine and are labour intensive too! Translate that into about  £1200 -£1500 a set for one offs and you can see why you don't see them used much.


I still love em though!

What wall thickness are you using?

Cheers.

Not sure, but TB's made scaled down models of parts before -are these full size or miniature?
Taz's trike build uses chunky girders, built for us by FLC, (Mick), from Yorkshire. I'm looking forward to trying them out. 

have to disagree with the not handling as well as teles bit.
teles are like vhs video, an accident of history, betamax was better than vhs, so same with teles.  tele forks have a spring inside a tube anlong with some oil which runs back and forth through various sized holes giving ithe front end damping. good rear shocks have the same set up but the spring on the outside, adjustable damping etc. mate that shock(s) to a girder front end which by it's very design, being trangulated is a very strong  structure, plus the trail changes very little in operation. yes the bmw idea is good as is upside downs. but a properly set up girder will handle with the best of them.
(http://i104.photobucket.com/albums/m185/dracken1/girders/gird5.jpg?t=1280524050)
(http://i104.photobucket.com/albums/m185/dracken1/girders/gird1.jpg?t=1280524089)
(http://i104.photobucket.com/albums/m185/dracken1/girders/gird7.jpg?t=1280524120)

Those look sweet.Are they brazed at the headstock.....it looks well sorted.

 ;D these are full size  ;D, 33 inches from the top yoke mount to the wheel spindle mount.
As for material ect, I did say at the start of this thread that i would not be going into great detail and thats purely beacause every application should be looked at on an individual basis.....as a general rule though (and only because you pushed me  ;D), for a `standard` set of girders going onto an `average bike/trike,` i would use 1" OD tube with a wall of 3.5mm ish. Need not be special tube, same stuff we build frames with is fine but (aint there always a but...) you will need to fit bushes into the links so seamless will save you the work of grinding the internal seam away.

Personaly i have to agree with Dracken on the handling, Girders are regarded as an old fashioned front end, couple that with poor quaility as an attempt was made to mass produce them and they are percieved as the third choice for bikes which is fine because they way we handle a bike is very different to the way we handle a trike. Having said that, unless you want to tear around at 150mph everywhere, girders will still out perform forks in looks, suspension and steering. 

Draken, the girder forks you display, are, I take it, a set of your own manufacture, and like the frames you have shown us in the past, appear to be of the same very high standard of construction. You bullet points I cannot disagree with, but must point out that the style of engineering shown comes at a fairly high price! one which many would not be in the market for, and therefore the ubiquitous 'tele' fork becomes a cost effective, mainstream, alternative. I am so old that I started my motorcycling career on girder forked machines, usually with worn out bushes and swaged pins! so their frailties have probably coloured my opinion! and well remember the revelation regards handling that the first pair of ex-W.D Matchless teles.were!Modern spring/damper units are definite improvements over the simple open springs and friction dampers of my youth! so, if you have the wedge, and want to be 'different', then modern girders it is. Alternatively, if you want cheap, serviceable and simple.......you know what I mean, still 'yer pays yer money....' , but better, I think not!TTFN, Morrag

yep I have ridden several and have had no issues with the handling to date, a couple had worn girders and they were awful but once revamped again no problems. I'm talking old 30's-40's bikes, rigid framed old chuffers that are never going to be racers  :D :D

Well,on old machinery from the period when girders were the norm, they are just about passible when in tip top order, however, my warning was to Hornet after his query re" powering out of long bends that you had been cranked over on!", yeah, right, there you go then, I'll go with teles. or even Earles type if its a trike, in those situations, thank you!...Morrag

did these girders ever get finished, if so is there any more piccies please

oh....erm..... no. When i started these i had an idea of what i was going to fit them onto, but i didn`t actualy have the frame which made fabricating the yokes impossible.

lol no worries  ;D ;D

Byzmax is the man you need if its girders your after, he`s done at least 3 sets recently  ;)

Hi.Just thought i would pick up this thread again. Ime still considering building my own girder forks for my next project.Ive been looking at the durfee girders which i can imagine, will be expensive.In their write up,they use chrome moly tube for its strength and lightness.Does anyone know how much it costs per metre,or is it safe enough to go with seamless mild steel.
My idea is to get all the parts machined and scalloped,and then i will make a jig to hold everything tight together while i weld it.I want to keep the rake at about 32 to 34 degrees.
Also,what type of shock absorber do i use? I was thinking of using a rear shock so that i could make adjustments between soft and firmer settings.Any thoughts greatly received.     

HHMMM got to admit my old Zed chop handled well enough and trust me that thing got hammered lol...Voodoo....

I like the set-up.Thats sort of what i want to make....but not as long.Did you make them yourself,and if so what material and size did you use?

Nope not something I would be confident enough to try and make myself....those things are about 20 years old now...Voodoo...

I`d be happy to go with mild steel tube, you only need seamless for the pivots.
cant help on the shocker, will be using a single spring on mine, when i get round to looking at them again.
Byzmax is still the man to ask about girders, drop him a pm and i`m sure he`ll pick it up next time he`s in.

Girders are fantastic things.

However no amount of clamping will stop them distorting. It's about welding process and doin stuff in the right order that ensures they come out straight. There was a brilliant website explaining the pro's and con's but it's of line at the moment. I'll try and post up some more thoughts on sunday perhaps when I have more time.

There are a set for sale on Britchopper never been used and at price you'd struggle to make em for.  £350!!

Click the link.  http://www.britchopper.co.uk/forum/viewtopic.php?f=41&t=27850 (http://www.britchopper.co.uk/forum/viewtopic.php?f=41&t=27850)

Think he is a member here... Maybe?

Any how suspension set up is trial and error. I usually fit any old rear shock and then guage from that what's actually required.

Standard steel frame tube (cds, cfs) In years gone by they where made from solid bar! You can Mig weld them but remember that the welds are generally short and you would do well to preheat the parts to ensure good penetration. Tig welding is better and if you can do it makes for a better finish. Accuracy of the finished parts is everthing.

There are lots of issues when building them much of which is related to getting the trail correct as they are generally built to order

Borgy. had them for sale.july last year £350.00 then

http://www.mankymonkeymotors.co.uk/forum/index.php?topic=8285.0

He still has them so PM  him as someone on Britchopper is showing interest in them ... You won't get a brand new set like this for that kind of money.... Of course you need to be sure they will fit!

Ok,thanks for the info. Ive just bought a second hand set off ebay.....purely to copy and make a  bigger set.The set ive bought are really narrow and small,only 26 inches from the top yoke to the center of the wheel spindle.When they arrive i will put a few piccies on ....maybe someone on here can identify which bike they came from.
I looked at the link that you sent me,and yes,they look great.Thats exactly what i want to try and make.Also it will be jigged up and clamped and Tig welded by yours truly. ;D ;D

One of the beauties with girders is once the yokes and links are made, you can make pairs of legs that are different lengths and just bolt them on.

Do you think it would be ok to use any type of shock absorber from an old japanese bike,say like an old bandit,fazer or hornet,just to give it some adjustment.....ive seen a couple of them that have used a trial bike shocker.

Taz's trike project has super wide girder forks built for us by forum member FLC, (Mick). They hold the rear wheel from a Yamaha VMax. Mick used an old 125cc bike shock, Honda I think.

You will be ok with any shock off a twin shock bike (don't use a monoshock). The angle and position you mount it will affect the way it operates and the effectiveness of the spring.

Fit any old one and see what it's like. Then to find out the spring rating put it on the bathroom scales or use another method and press down on it. However many pounds of pressure is required to compress the spring an inch is the springs rating.

60lbs = 1" means it's a 60lb spring.

Order a softer or harder one as required.     Sorted  ;D

 

Thanks loads for the feedback.....i just cant wait till this old pair come through the post next week. The more i think about it,the more ime thinking about making a pair to swap with the forks i all ready have in my project  ::) ::)

Ideally the pivot links need to be short as possible, to allow the offset to be nearer to std bike yokes, but this is governed by the length of the shock used. on taz's trike the links were 5" and the shock was 13" eye to eye (i think!?) but with a 45deg rake, on my chop they are 4.5" and 12.5" and 38 deg rake to keep the trail figure within reason. if this is not checked and set properly you can end with with negative trail which is where the vehicle is unstable at speed (very dangerous). think trials bike
reading this back it all sounds a bit complicated. i will try, once i get time to do some drawrings to explain this better.

 :D :D That's cos it is complicated  :D :D :  Sort of!

The hardest part about it is getting it all to fit and all the required components to sit where they are supposed to.

I can do it in my head and transfer it to metal but I never write it down>

Even the drawings make it look easy but in reality there are so many variables it's just suck it see.

I'll try and put some details up over the weekend with some pics too and between us all we might be able to produce something that makes some sense!

Thats great and thanks loads. Just want to gather as much info as possible even before i make any attempt to start on them.

HI...The girder forks i ordered of ebay have arrived.I knew they we,re small but i only bought them so that i can have a good look at the principle of how they work. They are roughly 26 inches long from the top yoke to the center of the wheel spindle.The gap between the fork legs is roughly 2.5 inches. I dont know how old they are,or what machine they was from. They are a bit shabby but rust free,so i may get em bead blasted and painted black again and sell them.
I took the side plates off the one side,and there appears to be no type of bushes at all inside the yokes.It seems like the bolts we,re hardend and the fork legs simply pivot on them.Has anybody got any idea what machine they might be from and a rough estimate to the age of em. 

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Look like they might be from an Autocycle Norman, Bown, or New hudson very narrow wheel size ?

Possibly early 50's Ambassador, or just prewar James, many lightweight Villiers engined bikes used this type of fork during the period late 20's to early 50's, often bought in from a proprietary supplier, and with "pressed" blades, like yours. Cheap and cheerful at the time, and not too clever then! so by now probably well worn to boot!give them a coat of paint, then hang them on the workshop wall as a "ialking point", which is about all their good for, believe me!  Morrag

Was reading an old britchopper mag (courtesy of Loonie) today, and there was a while article on building these, written by Mr Desperate! May be worth looking up, or drop me a PM and I'll run off a copy for you if you want!!

Thanks for the files you sent me....gonna make some interesting reading.cheers mate.

Hi.Ive studied the articles and at the end :desprate: says that if you send him an email,he will send you the plans to build a set...so thats what ive done...just gonna wait till they come through. ;D ;D

I have some plans for girders that came from the chopperhandbook forum.


Pm me your email and I'll dig em out and send em during the week.

theres a lot of reading that goes with the chopperhandbook plans. like any fork you need to work out your own length, rake and trail

Cheers byzmax,will pm ya soon. If i do make some girders,they will be kind of like a normal size,not stretched way out like some choppers have em. Will probably make em about 32 inches long between the top yoke and center line of the wheel spindle,with a rake of about 32 degrees.