AirHead Drag Bike

Packer

Thanks for the comments you have been reading my mind again.... the swingarm as you say is no longer going to have to take forces generated by going round bends but it will need to take some punishment from launching off the line with a sticky slick :green gri. The tyre growth is an unknown at this stage but what i can say is the side walls are really soft so if you were running a low pressure it could grow some, ultimatly if I can get some form of gusset back in the corners and in no way comprimise the tyre I will, even if its considered a bit belt and braces.
With the wheels not yet ready or tyre mounted this may have to wait its turn to make a informed assesment. I am hoping to get back to the rebuild of the swingarm Saturday so we could be a step closer to finding out.

Also been speaking to RM on beefing up the swingarm frame location similar to what he did on his Dakar bike - the jury is out on this one at present.

P.S no idea what's gone wrong with the photos of the packing box for the fairing :duno
 
Thanks Dave

Just been to see an old buddy who owns a surface preperation company today with a plan for getting the wheel hubs and drums blasted, he's going to try some different types of media and let me pick the finish i prefer, then I get to drive the machine and do the work myself this along with the Harley strip down could keep me busy as a fair bit of this bike is being treated to a bit of blasting.
 
Managed to get a couple of hours in this morning, we have turned up a piece of thick wall tubing which was to be pressed into the swing arm to ensure that when complete both halves would be straight across the swingarm pivot.

The tube was about 75mm long with a 5mm wall thickness this was pressed into one half of the swingarm.


Once in its final location it was tig welded with a couple of small tacks so when the other half was pressed on it didn't just slip through to oblivion here's a before




Next up the bevel box was bolted in place and the spindle used to help with the final alignment, the locating tube is not so tight we can't make radial movments if needed, we have also left the remains of the gussets in place as these are also a good referance of the origonal alignment.



The current state of play is these 2 halves are now pressed together the alignment looks good but we want to make some further checks before its tig welded. The new drive shaft side bearing is not yet made but on offering the arm up to the frame and using the pivot located on the taper bearing we look to have about 2.5mm clearance on the drive shaft size so ultimatly the new drive shaft bearing can be machined with 2.5mm stepped coller to get the perfect fit - or that's the theory.

Back at it tommorrow and Happy New Year
 
Thanks Dave

Just been to see an old buddy who owns a surface preperation company today with a plan for getting the wheel hubs and drums blasted, he's going to try some different types of media and let me pick the finish i prefer, then I get to drive the machine and do the work myself this along with the Harley strip down could keep me busy as a fair bit of this bike is being treated to a bit of blasting.

My local guy just uses extremely high pressure water, no media, on items that are not going to be coated and dont need a key. Not a bad finish for inaccessible item like hubs, as it seems to seal the surface rather than open it up, making it less likly to hols dirt and easier to clean.
 
Without any suspension movement the drive shaft no loger needs UJ's, could be one piece solid (or tubular) end to end, lighter and less parts to fail. That does of course assume perfect linear alignment but you'll want that anyway to minimise torque losses through the transmission.

P.S.

Sorry of Im stating the obvious.
 
Hi Packer

Something I hadn't considered but not sure we are going to get the alignment that good in both planes - will check it out once we get it back in the frame though.
We held off any futher work on the SW awaiting the new bearing so the BM didn't see much action today.
 
I would stick with UJ's in the shaft - you might well get perfect static alignment but I guarantee that once you let her rip there will be a fair amount of torque wind up in the chassis/rear frame/swing arm etc and it defo wont be aligned then!

I did think earlier about the set up, as you are going hard tail I think I would have junked the rear end/unnecessary swing arm parts entirely, and fabricated a subframe from scratch to house the final drive - less parts, less weight, stronger etc etc - but I do understand you course as well.

Just out of interest, why hard tail? - appropriate suspension can actually aid traction in this application.
 
Hi Solidstate

The drive shaft design is going to stay sort of how BM started it, this is proven kit and with the addition of a spacer this should be good to go, speaking to RM the side car boys use 100mm long spacers so we should be ok with something around 25mm.

Hard tail there are a couple of reasons, the bike will be running fairly low and our aim is to have the swingarm parallel to the ground so the distance between the swingarm and plunger towers wound need some bespoke shocks and springs for that length - could be an option though. The reason for keeping the bike sort of how BM started it is I really like the plunger frame design from an asthetic point of view and although we may be putting in a later engine etc hopefully it will still look something that raced back in the day.
The concept will need to be proven on the track when the time comes and maybe we may go to something bespoke and some form of suspension if needed in the future - speaking to some of the drag racing boys they advised that the tyre will provide a fair amount of give off the line and its hoped this will be sufficent, time will tell.
 
Hi Beemerboff

Not sure if this type of blasting is avalible at my my buddies place, guess it must be very high pressure ?

Maybe you could find out some more specifics on what this entails ?
 
Back on track today with the swingarm the main focus of attention, the drive shaft replacement bearing / bush was turned up.

We used the origonal bearing spacer for sizing of the O/D step which has been machined on the front face which is around 1.5mm deep to get the correct fit acrros the frame when its seated in the swingarm.







Spacer being pushed into position



Fully seated



And final welding

 
Got back to this project today and it was time to tackle the seat - no real reason sort of lost momentum on the swingarm. The drive shaft spacer has been drawn up and now needs turning having spoken to RM he recommended steel so that now needs to be bought.

Anyway the seat - its going to be a no frills affair ( read no padding ) so we already had some 2mm sheet aluminium but needed something to mount it too.
We had some nice seamless pipe from the every helpful Hampshire Hose - its 12mm dia so plenty strong enought for our application but it came straight:blast and we needed curved :rolleyes: so bring on the welding bottle which happend to be the correct dia to use as a template. Once we had a nice curve with a 200mm ID to match the ali sheet and the selected location on the frame we made up some keeper plates which when the whole thing is finished will be used to mount the ali seat base and fixed through with pop rivets.
So far just 3 welded in position.



We also wanted it the have a curve in the other direction hope the pic explains better that this sentance.... Note I am also sporting the new christmas gloves





Next we needed some back stays which were made of the same tube, again we wanted a curve so formed this using a hole in the car trailer and a bit of brute force, jump a few stages but this pic shows it in the final location and tacked in place. Part of this process was working out the best location for rider and clearance for the tyre we took measurments from the rear spindle to get its final resting place.



Here some further pics - next time we need to cut and shape the ali sheet



 
So about that seat base....

Needed to put a radius at the junction between BMW frame to new seat frame, the car trailer saw some action this time with some 3 inch SS exhaust tube, sash clamps and a small bit of heave ho.



Once we had the correct angle it then needed a further bend as the new seat frame has a slight tip at the top section.





Once the angle looked ok we marked out the seat frame radius and then cut this to shape. Next the front section going forward to the petrol tank mounting was marked out leaving it wider than the frame to allow some forming. This was cut to shape then marked out for a series of hole to be pop rivited in place.

Now rivited and the side sections folded round the frame tube.



And finally with the holes drilled off for the rivets around the seat tube.



It feels fairly comfy and the seat frame seems to hold you in place - as the saying goes its not built for comfort but speed but time will tell how this works out, we need to have the foot pegs in place for a final fitting:D.
 
Not much progress this weekend - the Harley had the front seat action but the ebay account has taken the BMW hit so we now have the materials on order to make the rear shocks or should that be solid struts.
Were going light weight so ali solid bar and some spreader plates to fit up inside the plunger tubes , 12mm rose joints...... having looked at alignment the longer swingarm the non dive side shock pickup is no longer in the correct front to rear location so this will need to be cut off and re made and on the the bevel box side a bespoke mount will need to be constructed. Looking on the net they seem look to join the rear wheel spindle and the origonal shock bolt together - they can then have 2 solutions - made out of billet ali or sheet steel and welded construction.
The jury is out on which way we will go at this stage but the plan is to make the struts first then see if which way we want to jump.
 
To prove we havent been completly slacking how about some struts - or just one if you want to be picky.........

Strut%202.jpg
[/URL][/IMG]
 
Neat way to build in simple ride height adjustment. If you incorporate a barrel adjuster it would be easier to use.

Good to see some progress.
 
Thanks Packer - the aim is to run the bike with the swingarm parallel to the ground but as both strut mounts need to be fabricated on the swing arm the rose joints should give a bit of flexibility and they look nice to boot.
 
So not much to report been slacking with the Harley still taking priority with over 4 years on this and the end in sight and first Mot looming.......

I have drawn up the drive shaft extension but this has not yet found its way into the lathe, so my next fill in job will be to design up the bevel box strut bracket.

Also been looking at details on Glemseck - no way the bike's going to be ready 2016 but hope to visit this year and check it out in preperation for 2017.
 
Ok I will admit it I have been slacking but a gap in proceedings today and some small progress.

So wheel bearings and seals fitted, even put new bolts and washers...

HB22.jpg
[/URL][/IMG]

HB23.jpg
[/URL][/IMG]

HB21.jpg
[/URL][/IMG]

Then for a bit of fun I thought i would turn a MZ into a BMW ;)

Badge3_1.jpg
[/URL][/IMG]

Badge2.jpg
[/URL][/IMG]


Even phoned up Moto-Bins and ordered new spokes for the front wheel, as this is still using a BMW rim so all spoke holes present and correct will have a go at building this to a complete wheel......now with that bust of activity..........
 


Back
Top Bottom