Rear drum to disc conversion

[scott s]

I know this has been covered before, but search isn't really turning up what I'm looking for. Plus, my question has a "twist" to it.

Let's say I have a '78 XS with spoked wheels; front disc/rear drum. I'm brainstorming about converting to mag wheels but I want to do the rear disc conversion that uses a front mag wheel.
Here are a few Q's:

1) I know Omars sells a kit, but can it be done at home with a little ingenuity?

2) Isn't it best to get a swingarm that has the correct mounts and tabs for a rear disc brake?

3) Are there any tabs on the frame (for the rear master cylinder, for example) that are NOT on a drum brake frame?

4) Give me as complete a shopping list as possible to make this conversion.

 

[scott s]

And while we're at it...

5) Since I'd have to source a rear master cylinder, are there any m/c from late model bikes that would work or perform better?

6) How do I identify a swingarm for rear disc? I take it that it's the one without the brake stay? Is that the only difference? Can I use a rear drum swingarm with rear disc?

 

[BigJimmyW13]

1) why not just find one of the rear disc mag wheels??? just for the size of the mag?
2) not sure. Probably not if you're doing the conversion, but maybe someone else could answer that better.

 

[scott s]

1) why not just find one of the rear disc mag wheels??? just for the size of the mag?

Because the stock rear mag wheel is 16". I want to run 19" wheels on both ends and convert to rear disc.
I'm just trying to gather the information I need and construct a "shopping list" of parts needed.

 

[BigJimmyW13]

In that case look for a rear mag wheel for an rd400 not 19", but they are 18".

Otherwise you're going to be doing Omar's kit which is $300 making this an expensive proposition

However,

Omars kit
19" front mag wheel
Rear master cylinder, switch and caliper
I would say the drum swingarm due to the fact that omar's kit is expecting you to be using it to swap out a drum
right length of brake line

 

[BigJimmyW13]

 

[scott s]

In that case look for a rear mag wheel for an rd400 not 19", but they are 18".

Aah, very good info.....

Now, how to mount the m/c to the frame and what m/c to use?

 

[scott s]

Do the RD400 18" front wheels fit the XS front end as well?
Since I need both mag wheels, a set of 18 inchers would suit me just fine.

 

[BigJimmyW13]

http://xs650temp.proboards.com/index.cgi?board=brake&action=display&thread=823

 

[BigJimmyW13]

Usually just consists of a spacer.

 

[scott s]

What about XS400 rear mags? I was just told they bolt right up. Would XS400 18" mags work on both the front and rear?

 

[BigJimmyW13]

No idea. If you were told that I suppose!? I am not sure though.