AirHead Drag Bike

Cheers Tom

if it all comes together there will be lots of photos to follow, maybe even one of the new engine in the frame....:eek:

Then we can sort out swingarm surgery
 
So wet and windy trip up to Northampton today met the legend who is Richard Moore absolute top bloke, and following a long chat about all things BMW we loaded up and came home with this....











This was sans the carbs which have been wrapped up for safe keeping and the gearbox which has been prepared to the same standard, there are some further bits to follow - clutch piston - starter motor etc.

Next step is to get it in the frame, from our initial assesment and much S@@@@@ing the frame needs a bit more treatment with the grinder, got to say I am well chuffed to have got this far in short order and its a credit to Richard that he has got this engine build done so quickly and in the time scale we agreed.

I will post some more pictures as this develops over the Christmas break......
 
Excellent! I take it the wheelie bins in the background are full of all those heavy bits that are no longer required:)
 
So some of those bits that make it go - and no wheelie bins in sight.....

40 Dellorto's





MSD ignition box



9000 soft cut rev limit..:eek::eek::eek:


Coil Pack - and i asked the same question and yes its 12v..
 
The frame has had some further bits removed today and a chat with RM has agreed an approach we are going to take to make the engine install a bit easier - well thats the plan.
Been out to get some thin wall tubing to make the seat frame so a few things on the bubble will post some more pics over the next few days as the hoildays have started at drag central..:beer::roll:drool
 
Some old TV advert used to say "power is nothing without control". If thats true you need one of these....hope its not sick from the boat trip for the USA...and wow how soft is the side wall.





Had the call from the David at "Vintage Tyres" that the race slick was ready for collection - had a guided tour of the place, I even spyed the steel billet dies to cast / mold some tyres :eek:
So after a good look round also picked up a new Avon front tyre and tubes + rim tape so all set in the wheel department - all in all a good day.
 
Good progress today, following the our last attempt to get the engine in its correct loaction had failed we moved to a new plan - put the frame on the engine.... involving some carpet a chain tackle, a green strop, a roof joist and some crossed fingers.




And its in... almost to easy


And now with gearbox


And from the rear :eek:


The gearbox is just held in place at the moment with some tempoary bolts so we need to check out the correct lengths and buy some suitable allen bolts but we can now use this to look at the swingarm mods.
 
Next stage get the 1970/80's swing arm to fit a 1959 frame - read angle grinder.....

So the 5 series swingarm was seleceted on a couple of fronts - choices of bevel box ratios and longer wheelbase + it looked like a challenge and the 5S arm would match up the new wheels 19mm wheel spindle plays 17mm spindle. Other considerations -5 inch wide slick tyre and its space requirements within the swingarm both side to side and also front to back around the pivot end. Wheel alignment - would be nice to have both front and back wheels on the sametrack. The swingarm will not be doing any swinging in its new home and the rear of the bike will be a hard tail with rigid struts in place of the plunger shocks.

The first part and main part to sort out was the width of the 5S arm at the pivot point which was around 20mm to wide for the frame, and a side issue from this was the drive shaft center line plays the gearbox drive flange location and getting these to play nicely. With the engine and box in the frame we moved them over to the drive shaft side and put in some washers to take up the small gap between frame and engine inner mounts to help our cause.
After some measuring and marking out we had a plan, first was to remove the drive shaft side pivot bearing then cut down this side tube by around 10mm effectivly moving the drive shaft when viewed from the rear 10mm to the right this bringing the gearbox and drive shaft center lines to almost perfect alingment. The plan is to replace this side bearing with a solid steel bush pressed in place more of this later...

The next step was the gussets that formed part of the design around the pivot tube these needed to be removed to help with clearance the tyre would need - clearly BMW put this gusset in for a reason to strengthen up the arm in this location and the long term plan will be to weld in place a tyre friendly gusset when its all finished but at this stage its get as much room as possible.

So as BMW intended + some grease and dirt.


Final job on was to cut 10mm out of the center of the swing arm this is how it ended up.


Now its in a pile of bits the drive shaft side was offered up with bevel box and wheel hub at this stage very much a jury rig but still we looked to have a almost perfect hub to center line of frame alignment, but with a lot of variables at this stage its just a hopeful light at the tunnel end.
What has also come out is the driveshaft is too short at the gearbox end and we will need to make up a spacer / spider again more on this later.

Mocked up in the frame.


Next stage will be the rebuild, making up various parts and alignment jig so this will be a strong as BMW intended and hopefully it may even fit when were finished.......
 
Rob / Solidstate

Thanks for the encouragement there may be a bit of a hiatus now for the Christmas period but just to wet the appetite I have some more pictures on how things may look in the future and some of the challenges.







Now if you squint on this one....
 
So Santa is sweating on the lawn not happy as this box just won't fit down the old chimney, so now worries we just dragged it through the front door.

Can you tell what it is yet.........



 
You can come round and help me fit it.......:rolleyes:

You said ex drag racer in your post above what did you race ?
 
Without suspension does the (non) swing arm need all the bracing? A lot of it would be to control twisting forces, with solid bars in place of shock absorbers there won't be any, it will only be the lateral forces you need to control and these could be done with external webs.

Secondly is that tyre similar to car drag race tyres in that ut grows significantly in use? If so, how much will it grow, i.e. how much clearance do you need to allow?
 


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