[f104wart]

Based on discussions and suggestions from the German Cafe Racer Forum, I was inspired to make the part even more delicate.

... And this is the result

... The proportions match and visually blends in very well with the overall picture from all angles.


What I think, it´s so porn, about it is that the rounded triangle can be found everywhere, regardless of the direction you are looking from.

... And quite by chance, the shape and width of the cutout in the hub also match the cutouts in the brake disc as an extension:

 

[f104wart]

With the brake caliper, the first question to be clarified was, whether I would place the caliper over or under the swing arm and how I would support the braking torque.

The easiest way would have been to use a pull or push rod and attach the caliper to a plate that presses onto the thru axle and hangs from a pull rod on the opposite side.

I didn't like this solution from a visual and also from technical point of view.

As well under tension as also under push the strut would only make technical sense if it supported itself on the frame. But she doesn't. It only directs the force from the brake caliper forward and thereby generates an additional torque.

Another problem that had to be considered was that the brake should be as easy to remove as possible to remove the rear wheel, since the rear wheel cannot simply be removed to the rear or down, as with a chain drive, but to the left Must pull the swing arm down from the final drive.



A torque-free support is only given, if the brake calliper is supported as close as possible to the axle, directly on the swingarm.

That's why I decided to attach the braking torque support directly to the swing arm and simply hang in the adapter plate instead of screwing it on.

For this, it was ideal to position the brake calliper all the way forward, directly above the swing arm.


A tip from the Cafe Racer Forum made me aware of the small Brembo P2 F05, which should be ideal for it due to its shape. In terms of the size of the pads, it also matched the brake disc very well and has 32 mm pistons.

This it should be!

First, a bolt was welded into the swing arm. Due to the all-round weld seam on both sides, the strength of the fork is not weakened by the hole!

The arrangement of the bolt in the neutral zone of the fork avoids any distortion caused by the introduction of heat during welding.

I drilled the bolt itself hollow for weight reasons. The pin on the inside of the swing arm has remained solid.


To find out the position of the calliper, a cardboard template was made and the shape and dimensions of the adapter plate were determined.

...then it went to the milling machine



When choosing the material, I opted for AlMg 4.5 (AW-5083) and a plate thickness of 12 mm. This is completely sufficient in terms of strength and, in contrast to AW-7075, can be anodized well.

It started with the two holes for guiding the plate on the axle and the braking torque support (position of the pin in the swing arm)

Then the hole for the pin was milled out towards the edge so that the plate can be pushed on:

And this is how the roughly sketched plate sits behind the swing arm:

The next step is to mill out the outer shape and mill the radii:

How this works quickly and easily on a conventional machine can be seen in this video:

...At the end a bit of fine work with a strip of emery cloth and the radius is round.

... continued in the next post

 

[f104wart]

The two turned parts that you can see here have a collar and are glued in with Loctite. They are intended to prevent the plate from tilting when the stud axle is pulled.

... And this is how it looks finished.

The screws of course will be replaced by suitable ones...

...that was rear

 

[D-Fresh]

talk about necessity is the mother of invention, wow! When there is a will there is a way, looks great, especially with what you have to work with. What material is the rotor made out of?

 

[f104wart]

Hi D-Fresh,

it´s AlMg4,5Mn0,7 EN AW-5083 (3.3547). This is relatively hard, sufficient in terms of strength and can be anodized very well.

PS: I hope, my english is well enough, also to understand the text.






...in the front it wasn't just as easy as in the back.


I have opted for the same brake calipers as at the rear. And as before, at the back, I first clamped the saddles onto the discs with compressed air to determine their position.

But that was just the opening credits. From now on it got interesting.


... Well. I knew the distance between the bores of the brake calipers and the distance between the bores on the dip tubes.

What I didn't know were the distances between the holes between the dip tubes and the brake calipers and their offset in the x and y directions or the angle. :? :

And everything that would be measured and calculated here would be crap in the end.

So there was a loooong pause for thought ...



During a visit to my friend Erich alias "RennQ" we sat in the workshop, drank cappuccino, talked gasoline, looked at photos and Erich showed me a few videos from Clickspring, as so often before.

... And with this video here it suddenly made a "click" for me 💡

... back home and the lathe and milling machine within reach, this tool emerged from this:

In the end, the idea turned out to be as simple as it is ingenious. : grin:

Two 8 mm thick aluminum plates each received two holes with M10x1.25 thread, which correspond to the distance between the holes in the dip tubes and those in the brake caliper.

The two plates are connected with sheet metal strips with an elongated hole and can be fixed in any position with the knurled nuts.

The screws are drilled hollow and rubbed to a fit of 6h7. These fits correspond exactly to the shank diameter of an M6 tap, the tips of which serve as center points for the holes.

The glued-on cones at the end of the screws fit perfectly into the holes to be transferred:

This enables me to tap the bores with an absolutely precise fit, without having to measure a single one of the unknown dimensions and not knowing it afterwards. Because I just don't need it!


The long knurled screw only serves to form a "tripod" and to be able to place the device for punching the holes on the workpiece.

The holes are pre-grained with the tap and then post-grained with a normal center punch:

The rest was then again just only drilling, thread cutting, sawing, milling, filing and grinding

 

[D-Fresh]

it´s AlMg4,5Mn0,7 EN AW-5083 (3.3547). This is relatively hard, sufficient in terms of strength and can be anodized very well.

I mean the brake rotor, the disc, what material is that?

 

[f104wart]

The disk is an original part from TRW. It´s made from extremely dimensionally stable steel
according to 35 HRC standard, hardened and thermally treated



...Here we go

If that had been it now, it would have been easy.

But Mc. Murphy, the old geezer, has to do his part too, of course.


I only had a millimeter of air between the plates and the floaters!

The TÜV (Technical Supervisory Assoziation) would definitely not agree with that, and apart from that, neither I don´t !

Milling the plate thinner from behind was not possible.

So, without further ado, the front wheel was dismount and dismantled again and the adapter discs turned off by 2 mm.

This meant that the discs and especially the floaters were further away from the dip tubes and the brake caliper brackets.

At the same time, however, this meant that the brake calipers also had to move inward. But, and that was the trick, without the holder being allowed to move further inwards!


The solution was simple:

The holders were milled off from the outside (!) In the area where the brake calipers are screwed on by the same amount as the brake disc adapter before.

Now the whole thing was looking better. This little "trick" gives me about 4 mm of space between the fixed and rotating parts. I feel more comfortable with that and that will also be sufficient for the TÜV.


Finally, some fine-tuning ...

...and the job was done for now.

The calipers just look great. Their shape and ribs go well with those on the engine, valve covers and oil filter. They are nice and small and with their two 32 mm pistons and the 300 mm brake disc are significantly more powerful than the original brake system.

 

[D-Fresh]

Very nice!

 

[f104wart]

Finally the brake calipers were then painted cast gray and received high-quality and visually beautiful titanium bolts.


...And for me as a former aircraft mechanic on the Lockheed F-104 Starfighter, it was a matter of course for me that the screws were secured with wire locks.

...And now, enjoy the pictures and the sound of this video.

 

[Samedward]

The rest of the waiting time I spent with polishing my handlebar-armatures


View attachment 203842


View attachment 203843


View attachment 203844


View attachment 203845


View attachment 203846

Now that's what I call reverse engineering

 

[f104wart]

Someday I got the idea to equip the 650cc with a hydraulically operated clutch.

To see if and how that works, I first installed it in my 500cc to test it extensively.


First of all, a device was built with which I can clamp the clutch cover in the lathe chuck as well as on the milling machine's rotary table and machine it inside and outside

And, like allways, also here the devil was in the details. If you want, you can try to determine the pitch circle diameter with a 5 pitch.

Since the cover is somewhat concave, it had to be faced in the area of the support surface of the slave cylinder. The motto here was "as much as necessary, but as little as possible", because firstly I wanted to keep the lettering and secondly I didn't want to weaken the lid unnecessarily.

The cover is reinforced by a turned part that is pulled against it from the inside and is supported on the reinforcement ribs. The lid is even more stable than in the original state.


The turned part has several tasks:

It serves as a counter bearing and provides the internal thread for fastening the slave cylinder. It clamps the cover and the slave cylinder together and rests on the reinforcements inside the cover.

At the same time, it seals the engine on the oil side with the O-ring and forms the guide for the push rod for transmitting the piston movement in the slave cylinder to the clutch release bearing.

So that the seal of the slave cylinder (brake fluid) is separated from the hot engine oil, there is a so-called groove ring in the hole for the push rod, which seals the hole to the outside and to the push rod. The U-ring (blue) can be seen quite well on the second photo.

On the third photo you can see the inserted push rod and the glued-in socket that fixes the U-ring in its seat.

Even the part is made of aluminum, it was quite heavy and was generously milled out on the back next to the threaded holes:

And this is what it looks like fully assembled with a push pin.

On the right in the picture you can see the glued-in aluminum plug with which the opening of the mechanical coupling shaft was closed

Because the release bearing of a hydraulic clutch, apart from the low spring force of the piston in the slave cylinder, runs without pressure, but still runs permanently, I replaced the original deep groove ball bearing with an axial ball bearing.

A lucky coincidence: the original push button from the mechanical coupling fits, inserted the other way around, into the axial bearing, thus holding the bearing in position during assembly and then forming the counter bearing to the push rod.

 

[D-Fresh]

You're an engineering/machining animal!!! Keep the ideas/pics coming!

 

[f104wart]

Tank you D-Fresh ...cheers 🥂

...please, tell me your name. It's so impersonal always to say "D-Fresh"






In the first attempts with an Aprilia and then with a 30 mm Oberon cylinder, the hand strength was too great.

The hydraulic gear ratio between the 5/8 "pump and the 30 cylinder just didn't match.

Since I didn't want to use a different pump, I looked around for another cylinder.

The choice fell on the slave cylinder of a Yamaha FZR with a 38 mm cylinder. This should improve the transmission ratio purely mathematically by 1.6 times. In practice it seems a lot bigger. So it fits now!



The inside of the FZR cylinder is very deep and has a dust protection sleeve that is fixed in a groove in the cylinder and in the piston:

Since I don't need the dust cover inside the engine, I turned off the piston and the cylinder without further ado and removed the edge with the groove:

Fully assembled looks like this

The cylinder is nice and flat and fits harmoniously into the overall picture.

The test on the 500cc has gone smoothly to this day and has met, if not exceeded, all of my expectations.

The clutch goes very smoothly. Since it has no play, you only have to "tap" the lever briefly and the gears slide in as if by themselves. No matter whether up or down. The moped has never been so clean and smooth. The gear changes are significantly shorter and more precise than with the mechanical clutch.

 

[f104wart]

... My today´s idea was to let the engine ventilation end in an aluminum bottle, which was once a special edition of a brewery in five different designs as "Pilot's Bear" with printed labels.

Since I didn't want a sharp-edged hole in the bottle, I initially made the hole a little smaller than the diameter of the tube.

Then I put a long M8 screw through a cone, which is used to attach the damper piston in the front fork,
Let the whole thing disappear in the bottle, pull the screw through the hole from the inside and flare the edges of the hole with the cone outwards.

That was easier than I had thought and resulted in a nice, even beaded edge, through which the hose can be pushed through without rubbing the sheet metal.

The cable tie is of course only provisional. I will soon build a bracket that will be screwed to the attachment points of the exhaust bracket and to which the bottle will be attached with the two leather straps.

Holes will later be made on the neck of the bottle so that the air can escape.

The hose is inserted all the way down and the bottle is filled with short compression springs so that the hot oil vapors can condense on the springs and settle on the bottom of the bottle.

 

[D-Fresh]

...please, tell me your name. It's so impersonal always to say "D-Fresh"

The name is Doug.

 

[f104wart]

Hi Doug, nice to meet you. My name is Ralf. 🥂

 

[f104wart]

.

I think it's time to show you another episode of my conversation.



The next step was to create beautiful manifold crowns, which I saw on another conversion and which can be bought at Cappellini Moto Germany for various motorbikes.

The design dates from the 1960s and was installed on various racing machines.


My intention was actually not to simply recreate the parts, but to change something. More on that later. Let's start with the final solution:


As almost always, it starts with a round blank that is turned flat and then lengthways. In this case on the later outer diameter of the manifold crown.
In the same set-up, the part was drilled with the thickest drill I have in the drawer.

Then the part was re-clamped and an attachment turned on from the other side, which only has the task of being able to clamp the part in the chuck of the dividing attachment for further processing.

However, before the part is put on the milling machine, it is turned from the back to the finished size, ...

... in such a way that there is still an edge at the front that will later pull the manifold to the engine.

The milling machine is followed by drilling and countersinking the two mounting holes
and then, on a slightly smaller bolt circle, drill the remaining holes

To ensure that the holes are evenly spaced, I used a dividing device.

This has different perforated discs with specific pitches, into which a pin engages when the correct position is reached.

The dividing head has a reduction of 40: 1. This means that you have to make 40 turns with the crank to turn the head once 360 degrees.

In my case I have 16 holes at 360 degrees and I use the 40 graduated disk for this. 40 divided by 16 = 2.5.


So I have to make 2.5 turns with the crank to distribute 16 holes evenly over 360 degrees.


I hope I was able to describe it reasonably understandably with my poor English.

 

[f104wart]

After drilling, the workpiece was approached from the outside and milled out between the fastening holes.
In order to keep the loads on my old FP1 as low as possible, I did not move the milling cutter into the workpiece in the X direction,
but milled from above and then further milled in synchronism.

It has proven to be very useful to document the individual steps and deliveries in a kind of "road book",
in order to be able to repeat them in exactly the same way for the second crown.

Next, a 50x4 mm slot cutter is used.

Approach, insert 12.5 mm and mill the first slot. Then approach the outer diameter, infeed 1.5 mm and the slot
mill in front of the fastening hole.

After milling the outer slot, move the table upwards and mill the slot of the 2nd row with the same setting in X.

Then scratch again, line up and finish the deep slots of the 2nd level.

... And so the parts "fell out of the machine"

 

[f104wart]

Now the parts were put back on the lathe.

In order to be able to clamp it from the inside, I clamped an 80 chuck into the 160 and aligned the component with the dial gauge.

Now the approach could be cut off and the back of the crown turned flat.

Then all the holes were deburred and the ribs and slots were briefly machined with a 240 and 400 grinding star from Steindl Tools and the parts were then glass bead blasted.

 

[f104wart]

.

Flashback


As I mentioned at the beginning, I tried not to simply copy the crowns, but to give them a "special touch".

For this you have got another bolt circle, which after milling has resulted in further ribbing in the axial direction.

It looked pretty good on its own, but it just didn't fit the moped. The parts were too big in diameter, with the 4 ribs too massive,
and with the jagged edges simply "too much".



For the sake of completeness, and because it was interesting from the point of view of milling, I don't want to withhold it from you.

Without the radially milled ribs, as in the 2nd photo, it might still have been an option, but I also wanted to keep the Cappellini design.

Even the 4-row version without the spikes was too bulky on the CX engine and looked like a foreign body.

So in the end I ended up with the variant with the 3 ribs and significantly smaller diameter ...

... and think that you have found a good compromise that also cuts a fine figure on the CX engine