MK2 with Aprilia Parts (In Progress)

Speeddevice · Post by **Speeddevice** » 10 Jun 2015, 08:39

I was considering the idea of converting my CRM into a motard but most wheel packages were too expensive.
The CBR 3 or 5 spoke wheels were at least $500, wire spoke wheels were well over $1000 but didn't have a cush drive.

Then a set of Aprilia RS-125 wheels came up cheap. They even had the forks and front brakes.

The challenges were;
* The front wheel fit and clear everything between the CRM forks. Modifications were required.
* The wheel bearings and seals are a different size. New seal & bearings required or needs spacers machined.
* Brake caliper adaptor bracket required.
* The Aprilia sprocket normally runs on the right hand side.
* The speedometer drive won't fit. Install an electronic speedometer like a Trailtech.

Here is some of the work to the front wheel to clear. It still needs the speedometer lug ground off the CRM fork when the conversion is carried out;

Here is a drawing of the bracket I designed to adapt the Aprilia radial mounted caliper to the CRM forks

I designed the bracket in 3D using Solidworks and was able to print a version out in ABS plastic to test the fit.
Here are the results;

The caliper will need to have the second boss drilled and tapped to install a bleeder in the top, it was previously mounted on the right hand side of the Aprilia. I will also need to get a new brake hose.

And here is the finished part machined from 6061 alloy;

Post by **rich1960** » 10 Jun 2015, 09:00

Wow.....very impressive....

Speeddevice · Post by **Speeddevice** » 16 Jun 2015, 10:25

Since I designed the part in Solidworks I ran an FEA (Finite Element Analysis) on the finished part to see if it was strong enough and where the weak points were.
With a bit of time I whittled away the part to almost half the original weight. It would be too difficult/costly to machine but could be metal printed in aluminium/stainless-steel/titanium. I thought about doing this but the cost would be a bit much for a CRM and there are much easier ways to save weight on the bike.
I did however print the part out in ABS to compare to the original design.

Here are a couple of renderings;

And the 3D printed part;

Speeddevice · Post by **Speeddevice** » 17 Jun 2015, 12:28

Here's a shot of it being machined on a manual mill

And the finished part with the caliper. I think I will have to shave the "Aprilia" name off and repaint the calipers to make them look at home on the Honda;

In the final fit up I found it needed a little bit of clearance for the brake pads

It is now getting anodized.

Speeddevice · Post by **Speeddevice** » 08 Jul 2015, 04:48

Forgot to say this before but thanks for the compliment rich1960.

Thought I better add a disclaimer in here...

*** Disclaimer - This is not a straight forward swap. Parts need to be fabricated/modified/bought to make this combination fit. ***

but you already new that now didn't you.

Ok. Back to business.

I was able to do a bit more work test fitting the rear wheel, as seen above.

New spacers were made up to adapt the RS wheels, which use a 20mm axle, to the CRMs 17mm axle.

There is also a spacer in the cush drive that goes inside the sprocket carrier bearing and takes up the clearance to the wheel bearing.

The next photo gives an idea of the machining done to the sprocket carrier.

Around 7-12mm was machined of the face to move the sprocket over closer to the tyre and miss the swingarm. The center which supports the lip-seal was also shortened as much as possible. There is still greater than 1D (1 x diameter) thread depth for the M10 bolts to hold the sprocket on.
There is now only just enough (7mm) room for the seal.

This photo shows how tight it is to stick this fat wheel under the CRMs skinny rear.

The sprocket will be countersunk and so that countersunk screw will sit flush with the sprocket. The bearing spacer will hold the swingarm about 1.5 - 2mm away from the hub.

Speeddevice · Post by **Speeddevice** » 08 Jul 2015, 04:54

This is how the sprocket lines up.

It is currently a 40 tooth. Could use a shorter chain or maybe a larger front sprocket.

The disc brake from the Rs matches the CRM caliper perfectly.

Here is a before and after shot from the rear

Speeddevice · Post by **Speeddevice** » 08 Aug 2015, 01:18

Update:

Have hit a snag with the caliper.
I split the caliper open to see about machining a new banjo fitting on the other end of the caliper, since the disc will be on the left hand side (Honda) as opposed to the right hand side (Aprilia), to allow for bleeding.

The first thing I noticed was that the trailing piston was a larger diameter to get even wear on the pads when used on the RHS fork. Not such a big problem but...
The other problem is that there is only one gallery for the fluid to crossover.
To sum it up, If I were to use this on the LHS fork I would not be able to bleed the brake properly.

So for the moment I will be looking for a new LHS caliper with the same radial mount bolt pattern or have to make a bracket to use the small CRM caliper.

Post by **gregorious77** » 14 Aug 2015, 22:01

Just bleed it off the bike?

Speeddevice · Post by **Speeddevice** » 15 Aug 2015, 12:10

A friend suggested bleeding it off the bike too.

I popped the pistons out and had a look. I think I may be able to drill the galleries, machine an o-ring seal for the crossover and machine a new thread for the banjo fitting.
I'll take a few measurements and plan it before doing anything.
If it's too hard I'll just bleed it off the bike.

Speeddevice · Post by **Speeddevice** » 17 Aug 2015, 23:20

I dis-assembled the calipers

It looks like the caliper halves are symmetrical front to rear. It is just the machining that is carried out which determines if it is for the left or right hand side fork mounting.

I can use a silicone or teflon seal for the additional crossover and it is possible to machine the passages if I can get the angles right. There is a risk of breaking through the casting and ruining the calipers so I need to weigh up if it's worthwhile.
I think I'll test it without machining if I can get the hose & banjo fitting to sit so it won't get in the way of the mounting bolts.

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http://www.speeddevice.com

mekros · Post by **mekros** » 18 Aug 2015, 03:27

I'm terrible at visualising things. Since the halves are mirror images, could you get another caliper and bolt two halves together that have the bleed nipples, block off the unused one?

Speeddevice · Post by **Speeddevice** » 20 Aug 2015, 22:13

Hi Mekros,

I managed to score the caliper & master cylinder in good condition when I purchased the wheels, that's been my main reason for using it. It also has a lot more brake pad area than the CRM caliper. If I was going to buy another I have seen left hand side calipers on ebay for ~$60 from a number of different bikes.

I've made the following picture to illustrate what I mean by the symmetry and the machining required.

It would also need drilling to create the internal galleries.
The new fitting would be at the top for a bleed nipple. I think I would connect the hose to the lower fitting, so the fluid would be flushed better. If the hose doesn't allow this then I would connect it to the top and block off the lower.

Post by **admin** » 23 Aug 2015, 12:27

fantastic work here (bit late to the party i know)

I think you should start making a few kits up and sell them as kits so us on this side of the pond can source our own wheels.
really impressive work

mekros · Post by **mekros** » 23 Aug 2015, 20:15

Speeddevice wrote:Hi Mekros,

I managed to score the caliper & master cylinder in good condition when I purchased the wheels, that's been my main reason for using it. It also has a lot more brake pad area than the CRM caliper. If I was going to buy another I have seen left hand side calipers on ebay for ~$60 from a number of different bikes.

I've made the following picture to illustrate what I mean by the symmetry and the machining required.

It would also need drilling to create the internal galleries.
The new fitting would be at the top for a bleed nipple. I think I would connect the hose to the lower fitting, so the fluid would be flushed better. If the hose doesn't allow this then I would connect it to the top and block off the lower.

That is the nicest way I have been told that my idea is idiotic

When I thought about it after your posts, makes total sense what you are saying. Nevermind me, I need more bike and tinkering time.

Speeddevice · Post by **Speeddevice** » 25 Oct 2015, 08:37

Not too much has happened since the last update however I did get the chance to take the bike to a friends farm.
The CRM is excellent offroad!

I have managed to give the caliper a nice coat of paint. The two hi-temp paint colours I had were Chevy Orange or EE Cherry Red. I went with the orange since it matched the graphics on the bike better than the Cherry.

I also have a 500 piece kit of aluminium crush washers so I can re-configure the brakes.

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Now to some up so far.
If anyone else is interested in doing a similar conversion my advice would be don't... unless you have access to a machine shop to modify the front wheel, sprocket carrier & fabricate other parts. It would be very expensive to pay for this work.
The RS wheels look good and are a nice light weight but it would be much easier to get CBR wheels or EXCEL wheels. I considered making kits of the spacers and caliper bracket but the additional machining is a bit hard to control.

If you like a challenge however, then you're the reason why I am sharing my drawings and experience in this forum. Best of Luck.

MK2 with Aprilia Parts (In Progress)

MK2 with Aprilia Parts (In Progress)

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