Category: Project Bikes
Below you can see the progress being made on the Carbon Bonneville bike, in place now is the rising rate rear linkage of a design so far found to be unique to Taimoshan Cycle Works and the tank has been modified and is taking shape ready to have carbon moulds taken. Also you can start to see the start of the seat/trial section styling and construction.
In later post, you will see the Bonneville T140 ES electric start unit that was acquired of ebay and is currently being refurbished and the “new” old stock lucas starter from a Norton Commando that will have the front housing replaced by a custom machined housing to mate it will the electric start unit.
Step 9 – Machining of needle roller thrust bearing housing for swingarm pivot
In this section I will show that final machined product of the bearing housings that will be bonded into the ends of the pivot section of the carbon swingarm. Each bearing housings contains a combination needle roller & ball bearing thrust bearing with inner sleave. This design will provide a low friction pivot joint.
here you can see the finished items with the bearings inserted ready for polishing then bonding into the swingarm.
Step 10 – Machining of the rear spindle carriers
These parts started off as 65mm dia FMA aluminium bar and were first machined on the lathe to the correct diameters and profiles and then set up on the milling machine and hand milled with a lot of care and patience into the final part which was … Read More »
Step 7: wrap carbon reinforcement of the whole section
In this post you can see part of the process of competing the Delta pivot mounts and further wrapping of the swingarm.
You will also see that I needed to provide clearance at the centre point of the swingarm as the swingarm would have fouled on the main frame at the expremities of the pivot range. The clearance was provided by cutting out a section of the reinforced tube and then bonding in anouther piece of carbon tube that I had made earlier for this purpose.
Next post will include details of the machining of swingarm pivot bearing housings and the rear spindle carriers that will be bonded into the ends of the main spas
step 5: main spar bracing core wrapping
The step involve adding another 2 more layers of plain weave carbon cloth over the whole foam core brace area. Again there are a few tricks to this process which I don’t care to to share but you can get the idea.
I will say that it is really important in these stages to take a lot of care in cutting the carbon cloth. To do this I first make card or paper pattern/templates of all of the pieces that I need to lay. I cut and test fit all pieces, taking a lot of care not to fray the cloth which is really fragile at this point. neatness is everything at this point and mistake can be hugely costly in both materials and time. I there is about £400-500 quid of materials and about … Read More »
step 4: main spar bracing core
After wrapping the main spar joints, I need to brace the main spar in the section infront of the wheel leading up to the pivot tube.
The reason for this bracing are 3 fold.
1) to add to the lateral rigidity of the main spars like a gussett. This hugely reduces the point loading on the wrapped and bonded main spar joints by spreading the load.
2) to add tortional rigidity to the structure. This is achieve with the specific laying up of different types of carbon fibre in the brace core and on the outside of the area. Layer the fibres at 45/45 deg to the direction across the flat area of the top and bottom of the brace will increase tortional rigidity of the structure.
3) to provide a platform onto which the suspension linkage mounts will … Read More »
Step 2: primary bonding of the main spars
On that the spar tube has been completed it is time to cut and shape the butt joints of the main spar tubes and then do the primary bonding of the joints, ready to then have the joints filleted and further reinforced in a later stage.
Although the image is not that sharp you can make out the that tubes have been shaped to make a close fitted shape around the circumference of the the pivot tube, the closer the fit the stronger the primary bond using the 2 part structural expoy adhesive.
Note that the bonding process needs to be done on an perfectly flat surface and not the wooden bench top!
step 3: filleting of the bonded joints, then secondary wrapping joints in carbon
Looks like I forgot to photograph the bonded part before … Read More »
Step 1: prepare the pivot tube and the 2 x main spars of the swaingarm.
In order to save time on this part of the project, instead of making the inner carbon tube of the 3 part construction process of the main spars, I bought pre-formed, roll wrapped pre-preg carbon tube of 38mm ID and 1.4mm wall thickness, these tubes are already very stiff due to their diameter, but they are not very impact resistant again due to their construction, however that with soon change.
So taking the pre-formed tube I then wrap the std tube in 5mm thick core material, using a technique that developed in which I spiral wrap the tube in the cor material, binding it in place with a roving of plain carbon.
Once the core material is firmly in place I then wet out the core with the … Read More »
After finishing the design, materials calculations and rising rate linkage for the swingarm for the carbon bonneville. I finally started on the swingarm construction following the process below. As the swingarm progresses I will add new post with photos of the construction and some weights ( just for interest sake).
The original swingarm weighs approx 3 kgs ( i will confirm exact weight in a day or so), I am expecting my extra stiff carbon swingarm to weigh in at about 1.3kgs, quite heavy in scheme of the project, when you consider that the whole frame as it currently stands without the seat hoop, weighs about 3.5kgs and a total completed weight of about 4 kgs.
The reason for the extra weight of the swingam is the fact that it is massively over engineered.
The original swingarm on some models is a 32mm … Read More »
In this post I am showing the development of another of the one off carbon fibre parts produced for the RS250. This small mounting unit fits in the section between the 999 tank and the sterring head/yokes of the RS250 and will serve to fill some dead space and also to mount the LCD temp readout unit from the RS250 display module, an essential item on any 2 stroke.
This unit was first fabricated ( hand shaped ) from foam then laminated with GRP, filled and sanded and a production mould taken. This is the first part out of the production mould.
The part then has a number of epoxy clear coats to allow the part to be sanded to a fine finish and then polished.
You can now see the part fitted in mockup to the bike. The LCD screen … Read More »
As you can start to see, the carbon fibre cafe racer seat unit is coming along, with the final version of the prototype being readied for taking the production mould.
After prepping and a lot of sanding the prototype is ready for another layer of resin, slowly building up the thickness so that the part can be prepared to a super smooth and glossy finish so that the production mould will have as few surface irregularities as is possible, this will ultimately reduce the final finishing of the production part and will yield a better quality part in the end.
A final test fitting to the Aprilia RS250 with its ducati 999 tank and the custom rear subframe. Starting to look pretty good.
(NB if anyone is interested I will be making these seat units available for sale when … Read More »