Danny's XS Hardtail...

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Prof
Founder, Choppers Australia
Posts: 5698
Joined: Sat Oct 22, 2005 3:54 pm
Location: Willunga, South Australia
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Danny's XS Hardtail...

Post by Prof » Sat Jun 02, 2018 8:36 pm

Danny brought his XS Special up today to get a hard tail installed. We had prevously discussed the pros and cons of me hardtailing it or him buying in a hard tail for me to attach. At the price he could get one from Trojan, I suggested he buy one. I installed a premade hardtail on an XS some years back and it went ok, so I expected the same of this one, but such was not the case.

Now don't get me wrong. I am not criticising another manufacturer or supplier (Trojan get theirs from USA). I am hoping this is just one bad apple. the problem with it being that it required heating and stretching to fit and most painfully, the axle plates are tilted 3mm to one side. Otherwise, the welds are neat and the frame tubing 30mm diameter and heavy walled.

First step with any hardtail addition is to get the bike level and tied down firmly. Levelling is best done off the side of the rear wheel. XS frames can be a bit touch and go as they are said to have often been bent out of the factory. I have found some interesting things on these frames including missed welds and really crooked gussets,but this one seems good, possibly because it is a later model. Notice centre line drawn on the 25mm particle board...
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Because we have to cut off the rear of the frame close to the back of the motor, we mount the bike on just the one cross piece and then tie all down with four anchors of soft (not high tensile) fencing wire. Once all are installed, they are twisted with a screw driver. This not only pulls it all down tight, but allows fine tuning of centring the bike...
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Plumbobs front and rear are used to centre the bike.
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Swing arm is removed and then the rear subframe cut off. Paul happened by and as he is a wizz with the sabre saw, he got the job!..
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Hey Danny! While the back half is off, let's rake the front half! Just kidding! (But I have to say it; would be much nicer to ride) Anyway stop dreaming, Hardtail ready to go on...
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Centre found on hard tail, by installing the axle and marking it as well as cross piece...
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Front of hard tail is off centre and too narrow by 8mm...
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Left arm heated and bent out 5mm. To get it centred right side needs to be bent out 3mm...
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Danny cleaning off paint with a flap disk in preparation for welding. Paint will contaminate the welds...
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After tack welding the bottom left rail, top rails are stretched upwards 15mm to fit around the back bone. At this point we also check the angle of the bottom rails and calculate how much drop we will have. I set up the hardtail with a slight upward tilt to get sufficient drop of the bike. Rear will drop 80mm at the axle which will bring the ground clearance down from about 8" to 6" inches... still a bit too high for a rigid with a narrow motor, should be 4" - 4.5" in my books. Legal minimum in SA if you are interested is that no part of the bike will touch the ground when both tyres are flat!..
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Bottom rails have to be stretched apart about 20mm. Scissor jacks are really handy for this stuff...
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Alignment and levels are checked with every action. Here the right seat rail is pulled outwards with a bit of heat and a very useful tool easily made in the workshop...
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More checking. Getting the whole thing square was a bit of a rigamarole, but we got there...
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Looks can be deceiving when looking down a backbone that is at a different angle to the seat rails. Although we have the rear end centred over the centre line with plumbob, we check by this method. Measure the diameter of the steering head and run a stringline back to the axle, marked at the same measurement... in this case 49mm... 24.5 each side of the axle centre. Because the axle is below the line of the the backbone, I place a thin steel ruler across the high point and lift then drop the string lines under pressure. That way they find their true straight line. We can now see it the string lines run parallel to the back bone... which thankfully they do...
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Now for the main problem; the tilted axle. Blue line on right is same length as the one on the left and shows that there is a 3mm difference to the seat support, which itself has been checked for level as we have been setting up the frame. I should mention here too that to two front ends of the seat rails were checked for level before welding. Left was welded in place and then a clamp was used to square up the right one. Important to be patient and check level before every weld. Up the front we will be welding in a large gusset to stiffen up that area and also to provide a locating surface for a sprung saddle. The last thing you want is a crooked base on which to mount the pivot...
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Hard tail tack welded in place. 80mm clearance from bottom of tyre to floor. The only solution to the crooked axle plates is to die grind out 3mm olong the bottom of the left slot and then weld in a piece of 3mm flat bar to the top. Danny will be thrilled with that job tomorrow morning when he comes...
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Chopit'nrideit... Prof

TriNortchopz
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Location: Haines Junction,Yukon, Canada
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Re: Danny's XS Hardtail...

Post by TriNortchopz » Sun Jun 03, 2018 2:10 pm

It looks like that was a tricky hardtail install; well done Prof. The photo with Paul holding the 'chop saw' is great! Good that Danny got involved too. It looks so much cleaner with that hardtail installed. Would it have been any easier in the frame jig?
So, when is Danny coming back for the rake job? 8)

Prof
Founder, Choppers Australia
Posts: 5698
Joined: Sat Oct 22, 2005 3:54 pm
Location: Willunga, South Australia
Contact:

Re: Danny's XS Hardtail...

Post by Prof » Thu Jun 14, 2018 11:23 pm

In retrospect would have been easier in the jig. Also extra time due to inaccuracies means we may as well have started from scratch. I have done a couple of others and had no problems hence the reason for suggesting he save money and buy a hard tail.

He definitely doesn't want any rake... will be to whip down to BWS and the supermarket he says.
Chopit'nrideit... Prof

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