Author Topic: Drum to Disc Conversion...anyone done one?  (Read 15387 times)

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Two_Wheel_Tuesday

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Drum to Disc Conversion...anyone done one?
« on: March 22, 2009, 08:39:33 am »
And just to make it more interesting.  I am looking to convert my CB550 (77) to the disc.  I wasn't sure if anyone has measurements on the swingarm from a disc 750.  Wondered if I could just swap it in.  Though I'm reasonably sure that the 750 is much longer in the rear. 

My thoughts were to grab the hub (spoked), and rear disc set up from a 750, and make a mock up on the 550 with the same set-up as an F1, F2.  Any ideas?! 

Thanks!

Elliot

Offline MCRider

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Re: Drum to Disc Conversion...anyone done one?
« Reply #1 on: March 22, 2009, 08:49:15 am »
And just to make it more interesting.  I am looking to convert my CB550 (77) to the disc.  I wasn't sure if anyone has measurements on the swingarm from a disc 750.  Wondered if I could just swap it in.  Though I'm reasonably sure that the 750 is much longer in the rear. 

My thoughts were to grab the hub (spoked), and rear disc set up from a 750, and make a mock up on the 550 with the same set-up as an F1, F2.  Any ideas?! 

Thanks!

Elliot
I have a 75 CB750F (or is it an SS? I don't even know) that has a rear disc. That disc is HUGE and I would like to replace it with something much smaller. Not to hijack your thread, but maybe someone knows of what I would need, then you could do the same.

I wouldn't put the 750 rear disc on a 550 if possible, it is just too big.

On the famous CB750 Big Benley, they used a front disc and carrier off a CB500 thinned to 5mm, and a cb350 caliper, looks much more proportional, though still bigger than i'd like, than the stock rear 750 unit.

Of course they had access to machinists to make what else was needed, wheel spacers and caliper bracket.
« Last Edit: March 22, 2009, 08:54:10 am by MCRider »
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Offline voxonda

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Re: Drum to Disc Conversion...anyone done one?
« Reply #2 on: March 22, 2009, 09:51:51 am »
Sadly got no pictures left, but once build a rear wheel setup for a 500. Used a front hub, machined a carrier for a 250 mm, 4.5 mm thick, Ducati disk and machine a carrier for the rear sprocket. Used high grade rubber bushes as transmission damping. Worked very well and was light!! Made sure to use heavier bearings in the hub. If I see the man again will shoot a picture. Can be made again.

Cheers, Rob
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Offline fishhead

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Re: Drum to Disc Conversion...anyone done one?
« Reply #3 on: March 22, 2009, 10:20:18 am »
I put a CB 750 F rear disc wheel on a 750 K model swing arm. I had to machine some off the caliper bracket to fit in the swingarm and use the K sprocket drive and figure out a master cylinder mount. I dont know how easily it would transfer to the smaller bikes.
 I usually go to extremes when I convert mine to rear disc. With the CB rear disc brake set up ,you are usually stuck with the big heavy Honda rear disc and when using a front hub for the rear, there is more room for options for different discs.
 Front CB 750 hub laced to a 18 inch rim, sprocket adaptor, spacers and disc adaptor. The two piston caliper is off a newer sport bike and I made the adaptor for it. The bearings had to be changed to 20mm and a 3rd bearing was added in the sprocket adaptor.
   Honda doesnt offer much when it comes to changing to rear disc brake wheels. Yamaha has alot more options for changing the rear to disc brake. There are some aftermarket wheels that make the conversion easier (Morris, Shelby Dowd).The last pic shows a Shelby Dowd rear disc wheel.
 
 
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Re: Drum to Disc Conversion...anyone done one?
« Reply #4 on: March 22, 2009, 11:07:05 am »
That Shelby Dowd set up is what I would like. Think that can be had for about $50?   ;)

Your front hub set up is sweet, but looks like a lot of work for someone with few skills like me.

I think it was LordMoonpie said there was a place that would put a cast iron disc on your own carrier. I was thinking of that with a real small disc, and then fab up the caliper mount for a small caliper.
« Last Edit: March 22, 2009, 11:09:06 am by MCRider »
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Re: Drum to Disc Conversion...anyone done one?
« Reply #5 on: March 22, 2009, 11:10:44 am »
Sadly got no pictures left, but once build a rear wheel setup for a 500. Used a front hub, machined a carrier for a 250 mm, 4.5 mm thick, Ducati disk and machine a carrier for the rear sprocket. Used high grade rubber bushes as transmission damping. Worked very well and was light!! Made sure to use heavier bearings in the hub. If I see the man again will shoot a picture. Can be made again.

Cheers, Rob

That sounds sweet. I'm a long way from needing it, so just talk from me for now.  Maybe OP TWT would be interested?
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Offline Ricky_Racer

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Re: Drum to Disc Conversion...anyone done one?
« Reply #6 on: March 22, 2009, 11:26:08 am »

Okay, since we're on this subject. I think this topic will hold a lot of interest for a number of people. The issue is external cush drives. I have one bike with a front hub mounted on the rear with appropriate spacers. No cush. Many aftermarket wheels are available with no cush drive. It's probably okay to run without a cush since Rickman and Seeley seem to get by without one, but I still think it's a good idea.

With the wealth of experience on this site... Has anyone come up with a good universal design, and more importantly, where did you source the rubber inserts? I've considered hockey pucks as a rubber source. Opinions?

Thanks!  RR

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Re: Drum to Disc Conversion...anyone done one?
« Reply #7 on: March 22, 2009, 11:37:24 am »

Okay, since we're on this subject. I think this topic will hold a lot of interest for a number of people. The issue is external cush drives. I have one bike with a front hub mounted on the rear with appropriate spacers. No cush. Many aftermarket wheels are available with no cush drive. It's probably okay to run without a cush since Rickman and Seeley seem to get by without one, but I still think it's a good idea.
With the wealth of experience on this site... Has anyone come up with a good universal design, and more importantly, where did you source the rubber inserts? I've considered hockey pucks as a rubber source. Opinions?

Thanks!  RR


Referring to the Big Benley project done by patrick bodden Dec 1999 Motorcyclist magazine, they used CB450 Drive Cushes and studs. If memory serves these are 4 individual rubber mounted cushes that could be inserted into a hommade drive plate. They then each hold a stud for the sprocket. A fiche for the CB450 should show them.  OEM Honda material, should be strong enough.


The Big Benley CB750 article and comments from those who were there, is also in the thread that is stickied to the top of the SOHC4 forum about the original CR750.

PS: I just went to BikeBandit and those CB450 drive cushes are discontinued. About $10 each.  >:(
« Last Edit: March 22, 2009, 11:44:26 am by MCRider »
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Offline voxonda

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Re: Drum to Disc Conversion...anyone done one?
« Reply #8 on: March 22, 2009, 11:47:01 am »

Okay, since we're on this subject. I think this topic will hold a lot of interest for a number of people. The issue is external cush drives. I have one bike with a front hub mounted on the rear with appropriate spacers. No cush. Many aftermarket wheels are available with no cush drive. It's probably okay to run without a cush since Rickman and Seeley seem to get by without one, but I still think it's a good idea.

With the wealth of experience on this site... Has anyone come up with a good universal design, and more importantly, where did you source the rubber inserts? I've considered hockey pucks as a rubber source. Opinions?

Thanks!  RR



I am employes, for the last 30 years, in the metal packaging industry were I design and build dies for forming of lids which are put on top of paint pails. As a internal spring we use rubber 'springs' in different shore's. I use them as cush drive rubbers.
Here a smac wheel I fitted a cush drive on:

Notice the extra bearing in the cushdrive outer plate.
Maybe a bit clearer:

And the one for my former CB900:
« Last Edit: March 22, 2009, 11:57:58 am by voxonda »
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Offline Ricky_Racer

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Re: Drum to Disc Conversion...anyone done one?
« Reply #9 on: March 22, 2009, 12:20:02 pm »
Hi Vox and Dan! I sort of expected that you'd be the ones who'd done this job already. Nice!

Second question?  Vox, can I get a small supply of this rubbers and some indication of the diameter of hole you used to hold them?  Pleeeease?

And will you be at SPA this year? 

And does anyone else have experience building cushes?  I've attached a photo of the Magni cush drive.  Thanks.  RR



« Last Edit: March 22, 2009, 12:21:52 pm by Ricky_Racer »
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Re: Drum to Disc Conversion...anyone done one?
« Reply #10 on: March 22, 2009, 01:46:52 pm »
  Morris used a rubber grommit where the sprocket bolted on to the hub, kind of like the top shock mount (bolts with rubber around it). The holes in the sprocket were oversize and the bolts were cushioned by the rubber between the mounting bolt and sprocket.
  My set up has been with out the cush drive for over 2 years and I havent had any problems with it (I'm not doing holeshots, either). I dont think I'll have any problems with it , but I do check the spoke tension more than I did when I had the cush drive. On my set up, the disc bolts hold the sprocket adaptor on and I added pins/collors around the bolts (the bolts hold it together, the collors keep the rotational forces from sheering off the bolts, my theory). The Shelby Dowd wheels didnt have the cush drive either.
 The Yamaha XS 650 guys convert the front wheels to rear use alot (19 inch) and that where I got the idea. Omars sells a kit (adaptors) to put the front wheel on the rear.  My set of stock (I think)Yamaha Pentagram wheels also dont have the cush drive.
 The main reason I didnt made my rear wheel have a cush drive is simple. Adding a cush drive would have added alot more work to what was already alot of work. My Shelby wheels didnt have it and it worked fine with them, so my theory is that it would (and has) work fine.
 
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Offline voxonda

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Re: Drum to Disc Conversion...anyone done one?
« Reply #11 on: March 22, 2009, 02:08:19 pm »
Hi Vox and Dan! I sort of expected that you'd be the ones who'd done this job already. Nice!

Second question?  Vox, can I get a small supply of this rubbers and some indication of the diameter of hole you used to hold them?  Pleeeease?

And will you be at SPA this year? 

And does anyone else have experience building cushes?  I've attached a photo of the Magni cush drive.  Thanks.  RR
Hi RR,
I use the polymer rubber from a company called Effbe from Germany. They come in several sizes.
Outside diametre 32 and the hole is 10, but can be turned an the lathe.
Use them for the real cush drives. You can also build the cush drive in the sprocket. For that I use rubber that I order cut to size. Will you be at Spa this year? I can take some with me. Would take care of posting.

Cheers, Rob



« Last Edit: March 22, 2009, 02:31:07 pm by voxonda »
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Offline Ricky_Racer

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Re: Drum to Disc Conversion...anyone done one?
« Reply #12 on: March 22, 2009, 02:28:35 pm »

Thanks, Dan. I'll pull a couple of my Morris wheels apart and see if I can find the cush rubbers behind the adapters... I assume that's where they'll be.  You're probably right about not needing cush drives in most cases, but unfortunately I love horsepower and I do love hole shots!  Plus, it's just something else to busy my "between assignment" days with.

Thanks, Vox. I'm absolutely planning on being at SPA this year. Last year I was working and couldn't attend. I'm glad to hear that you're going. If business goes well until then, I might even want to buy a some of your handiwork and pick it up there. I'll check your website for goodies. Please do bring a sample of the cush rubbers if you would. First beer is on me! RR

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Offline 754

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Re: Drum to Disc Conversion...anyone done one?
« Reply #13 on: March 22, 2009, 09:47:23 pm »
I got a set of Morris cushes somewhere.

I believe they were urethane  bushings, or  similar, they had a steel spacer in the middle, and a plate on each side. The holes in sprocket were oversize, and fit these bushes, then a flat spacer on each side. The mounting bolt tightened on the cush sleeve and 2 spacer plates, locking all that to the hub. Then under torque the steel sleeve would move in the soft bushing, to have some give.

They could easily be made on a lathe, believe they were optional.

I built a few dragbike hubs, they mount solid.

Rad Mfg in Utah makes cool straight pull hubs, they have one model with cush drive, I believe it comes off, and may be fitted to another wheel?, cool gobs of anodized aluminum, you may forget about mags when you see them.. ;D
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Re: Drum to Disc Conversion...anyone done one?
« Reply #14 on: October 24, 2011, 05:47:54 pm »
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