Circumventing the RidikulusRool Peter's Evo Chopper derake...

[Prof]

Peter's newly purchased machine originates from interstate and therefore needs a number check to be registered in SA.

They will check for general adherance to SA Road Rules (can't call it roadworthiness!!!) and the front end looks to be out past our nanny state's Ridikulus550Rool. A phone call and he cruises over so we can do an accurate check and come up with a solution.

RR states that distance from centre of steering head to axle centre on a horizontal plane must not exceed 550mm. Way to check this is to use a set square and ruler to find steering head centre. Then measure across to the axle.


Hmm! 75mm too much. Axle needs to be back to the end of the aluminium ruler. Headstem bearing cups with an inbuilt 3 degree rake are available for most HD's. So question is; can we put them in backwards and bring the axle back 75mm?


We set up a piece of 1/2" square tube at minus 3 degrees using a large protractor...


Move second square along to where the axle will now be and it should be within a few mm either way...


Peter will come back in a few weeks and we will give it a go, as I have the correct 3 degree cups in stock. To suit HD's without removable bearing cups the 3 degree jobbies come with a longer head stem which we will need to modify to suit the custom triple trees that come with this chopper.

If we are still 5 or so mils to far out we will shorten the spring spacers which will pull the wheel back. Don't have a lot of ground clearance, but should be sufficient. Time will tell.

One his way over Peter hit a nasty dip/hole in the tarmac and was still hurting (the air shockers leak so no rear suspension until they are replaced). To get him home more comfortably, we pulled the covering off the rear of the seat and added some new foam where the old stuff had collapsed. Gave him a call when he arrived and he said it was far more comfy. See you in a month mate.

[El Skitzo]

Hmmmm, good luck...

[Prof]

Back in the workshop for a couple of weeks and at last catching up on jobs.

A couple of quickies. Apehangers on a Hunter required lengthening 12 sets or wires, a new clutch cable, modified throttle cable and setting up a choke using a Velocette advance/retard lever. More on this in a separate post...


New sprocket cover on Rob's sporty allowed me to build a set of pipes to his design and mount the rear brake cylinder and connect up to the forwards. More on this on his post elsewhere...


Now an emergency job for Peter. Needs to get his bike through Regency in a hurry, so squeezed him in today and tomorrow. We previously worked out (see previous post) that 3 degree cups in reverse and dropping out spring spacers would get him back to 550 RR. He took a 3 degree kit home to install it and was stymied by a weird steering head. Seems they used a piece of solid bar and only drilled a hole thought it to just fit the 1" headstem... no room to angle the headstem absolutely zilch. Back to the drawing board.

In the meantime, I had ridden up to his place and looked at the chopper minus its fuel tank. Bodgied mess on the backbone a few inches behind the steering head = cracked backbone despite the bog covering it!!! I had previously advised him once registered to get some extra gussets or tubular support into the headstem area. What I figured was a hidden crack confirmed it. So, desperate to get the chopper registered Peter asked if I could slip in his job. Two days should cover it, so I agreed to slot him in...


He'd taken out the old bearing cups before realising things wouldn't work so we dropped off the front end and installed new outer races and then did some measuring...


I hoped we might be able to get back to the 550 by removing 3" of spring spacing (any more and the front would be too low) and using some standard triple trees which have half an inch less offset. He could then put it back as it was after regio if he wanted to. Alas, as you can see from the measurements we were still 18mm (3/4") too much. Peter had had enough of mucking around and said, "Let's just derake it so it meets 550.


A close look at the bodgied bit showed a crack and shocking welding. So that piece needed to be cut out. Person in background is my new workman, Lionell who is doing well; here dismantling Garry's Twin Cam ready for us to get the motor up on my jig and then build the new frame...


Here's the offending piece with bog and paint removed. Someone had tried to weld a piece of 1.6 mm steel around the weld!! Unbelievable!!!!!




Ok. We have three jobs. Move the steering head forwards at the top to reduce the rake, rejoin the backbone, strengthen the whole area. Peter cleaning off paint with a flap disc. Tomorrow he'll get into the tighter parts with die grinder etc. Paint contaminates the weld, so it has to come off completely...


Here's what we have. Will have to heat down tubes low down to do the derake or alternatively remove the piece behind the headstem and make it more like a modern goose neck. Advantage of the second method is that handlebars won't be taken so far forwards our of rider's reach...


Here're the basics of the strengthening process. Natural tendency of backbone is to try to bow downward at around the back of the missing bit under the choppers weight, and bend upwards due to the forces from forwards movement. So 1. New piece installed to fill gap (1). 2. Backbone needs to be a larger diameter for the size motor and forks this bike is carrying. This will be done with a tube with the same ID as the existing OD. It is split in two (A&B) and drilled for plug welding as well as full length welding along the cut sides. Weld along sides will both join the two pieces and tie them into the existing backbone. 3. A curved tube will be installed (C) It will also be attached to the tube that currently carried the forward tank mounts. 4. Peter wants to retain the flames at the back of the steering head, so we will just fill in the add hole inside the flames to increase weld area of frame to steering head...


Peter will be back tomorrow for a short time and again on Thursday. I hope to get it finished by end of Thursday as I have to take off to Pt Pirie Friday. I had wanted to have my front guard done for the trip in case I meet up with a traffic cop on the way... so will just have to say my prayers on that one. Monday I can then get on with raking the VTX 1300 whose owner has been very patiently waiting.

[Prof]

Back onto the chopper for a few hours the following morning. Jack the frame forwards and see what happens with 550 rule. Need 80mm, but after a fair bit of pressure only gain about 30mm. Down tubes are basically bending from near front engine mount and just doing it this way will mean pushing steering head well forwards and away from rider. Alternative if we just use jack is to heat down tubes just below steering head and create a mild gooseneck. Back bone will in both cases need to be lowered. there is another solution; drop the front end by shortening the spring spacers...


A few measurements up the lower legs suggest major gains this way; in fact about 75 mm shorter will do it. This will also allow him to put them back later and have the kind of chopper he wants. Pull off top tree and remove nuts on top of forks. Spacers are around 250mm long...


Use bike stand to alter bike height to get the effect and yes, does the trick... now within 550mm...


Peter makes up some new spacers from water pipe. Make sure you scrape/blow out any residue if using old pipe...


You can't read the ruler in this pic but with new spacers installed and chopper sits about level, still has some suspension and is at about 530mmRR...


Rake is now 36 degrees...


I am going to fab a curved tube to lock the backbone into a gusset between the down tubes, so front tank mount needs to be cut off. Measure up distance between mounting holes. Peter will bring tank down next time so we can reconnect the front mounts...


Tube bent with heat to a pattern made from ally welding wire...


Tube has a 3mm wall thickness. Have used heavier gauge than I would with a straight section, because a curved shape can flex so is not an ideal gusset even supported part way along. Extra wall thickness will give it a bit more stiffness...


Bent and testing for fit...


A lot of custom frames look 'killer'... and a lot of them are. Insufficient support for steering heads 'way out there'' especially with the modern massive motors and front ends and overall heaviness. I have photos of a number of custom frames that I have needed to rebuild and strengthen in this area. So we are adding a long gusset between the down tubes. Think about the twisting force when cornering at speed especially on our rough Australian roads...


Way to get an even curve is to fold the card in half and then cut. Open it up and you have an even curve...


3mm steel gusset is cut. See other posts for cutting out the curve. Here being finished with the angle grinder before a final touch up on a small sander I use...


When tack welding in the gusset it needs to be straight. This is achieved by using a straight edge across the frame tubes and measuring each side with a ruler or verniers...


Gusset welded in...


Curved tube now final fitted. I am going to suggest to Peter that we move the flame section so a flame tip can be welded to the curve for that bit extra rigidity. It all adds up timewise, but better done once properly than a chance of it needing further work later on...


Backbone is now squared up....


Fitted to back of steering head...


A short slug will be made from some hollow bar to lock in the rear of the new section. Next job then will be plating the whole backbone, which should happen Monday...

[El Skitzo]

Wow that's a lot of work, well done on finding a solution.

Always pays to know about the 550mm rule before buying a bike.

Great pics too, as this will all be very relevant when we chop my Triumph frame to stretch it.

[Prof]

Glad to be of assistance. That's what we are about. Looking forwards to seeing your progress...

[Prof]

Back on the job Tuesday and finished the project at 6.45pm; total of 13 hours...

Reinforcing tube welded in. Vertical support is part of original tank front mount. Helps prevent the curved tube from flexing. Flame will be moved an joined (on a tip) further forwards to help further stabilize the tube...


Now to permanently install the replacement top tube piece. I will slug the join for to produce as much rigidity as possible for this area. Slug is a piece of hollow bar that needs very slight machining to fit inside the backbone. Standard practice is for slug length within each piece of tube to be a minimum of 1.5 times the ID of the existing tubes...






Slug machined. To fit it, requires the slug to be fully inserted in the short tube, which is then slid into place and the slug moved forwards.Both pieces of backbone therefor need to be slotted...


Slug tapped into place using a drift punch. Short section of backbone is now welded at join (plus slot welded in ) and at steering head...


Existing backbone is not sufficiently strong for such a heavy and powerful chopper, especially with such a high and out front steering head. It is now to be 'plated' with a tube that fits snugly over it. Unfortunately I had to buy a full length of pipe(6M) to get the right size piece (800mm). Looks like I'll be doing a bit of overkill on the backbones of future choppers as it is a bit larger than I normally use. Here Peter is splitting the tube in half. To hold it in the vice a piece of pipe is slipped into one end. A tight fit which was just the ticket...


Checking backbone for straightness...


First step is to fit each half to the steering head. Side sits back 15mm from steering head so that is how much will need to be relieved on top (see texta mark)...


Halves have to be notched and relieved along their lower edges to clear engine mounts etc...


Takes a lot of trips to linisher and grinder to get them right, as we don't want any big gaps to fill. Check for straightness of backbone as tube has a bit of a gap at the rear. It's straight, so check our larger tube half...


When tube is split it often is under tension and curves slightly as did this one. A couple of gentle nudges (one was too far) on the press gets it fitting nicely. Sleeves will be welded down each edge and at half a dozen places along the sides (plug welds) so needs to fit. Any gaps at the welds will put things under tension and could pull the frame out of alignment.

We have not set this frame up with plumbob and laser; 1. to keep time down, 2. Because steering head has simply been pushed straight ahead without cutting the down tubes, so if we are careful, it will stay in alignment...


Both halves welded and plugwelded. This is done slowly and in short welds keeping in mind a long weld or groups of welds along one side without alternating with the other, WILL pull the tube our of alignment. Welding is spread out over an hour to let things cool and stay straight...


Flames are cut off and the paint removed. A 25mm piece of 4mm is shaped (wide strip at bottom of photo) and welded on to the flames...


Here fitted. This has moved the flames rearwards so one tip can be welded to the curved tube (white arrow). This is not a major support, but will hopefully provide just a little extra rigidity. Cardboard pattern made for other piece of filler...


Welded in a the tank set up...


Tank bracket is now welded back in place...


Just one little piece needed to finish flames off nicely...


How do you hold something this small and weld with out burning your fingers? Just tack on a long piece of scrap as a handle. Break it off when the piece is welded in...


Job done. Steering head deraked slightly combined with dropped forks keeps us 10mm within the Ridikulus Rool...


6.45pm and time for Peter to get home which is over an hour away and he doesn't want his car to be roo bait.

Chopper loaded and ready to have some tidying filler and then paint. It'll be on the road soon so keep your eyes peeled. Not my style, but Peter loves the big motor and rear suspension for longer trips something his classic CB750 is lacking...


So it's buyer beware. Big, heavy, powerful choppers need strong frames especially around the steering head. I shudder at the flimsiness and lack of gussetting I see on many of the modern Long Bikes. This one was definitely a prime example. Cracked around 3/4 of the backbones diameter, made this chopper a potentially serious accident waiting to happen. If that frame gave way on a bumpy left hander at speed and put the rider into an oncoming vehicle... I shudder to think about it.

If you are buying a custom frame, make sure it is well gusseted and strong before yo paint it. Better an extra $800 worth of prevention now than the consequences of an accident in the future. If you aren't sure, ask someone with qualifications or experience.

Safe chopper riding folks!