Author Topic: rear disc brake swap (Read 16343 times)

turboguzzi · « **Reply #25 on:** November 25, 2010, 09:08:26 am »

Quote from: fishhead on November 25, 2010, 05:05:18 am

  The "big" discs just look like they are big. They are actually about the same size as the stock F and GL rear disc, just a lot lighter.
   This pic shows the new "big" disc mounted with the stock caliper (GL 1000). The pads on the stock GL caliper would hit the buttons on the disc and couldn't be used like this (and the new discs is a lot thinner than what it replaces).

I see, if these are 16" rims that could explain the illusion. What's the diameter in these?

fishhead · « **Reply #26 on:** November 25, 2010, 10:01:27 am »

Thanks for the compliments,

All of the rear wheels shown are 18 inch.

Here's a link to Randakk's GL 1000 with the front and rear brake kits on it. His kits were custom made and the 7 "spoke" discs were specifically chosen to match up with the 7 "spokes" of the Lester wheels.

http://www.randakks.com/Randakk%27s%20Endurance%20Special.htm

(His CBX also has one of my front brake kits on it,too)
Randakk's CBX

http://www.randakks.com/CBX%20Farkles.htm

IE: smaller rear discs=

The newer application rear wheels have more room near the axle for the smaller discs and closer (to the axle/hub) mounted caliper. The older application rear wheels do not have this room/clearance (near the axle/hub) so most of the times a smaller disc can't be used because there is simply not enough room/clearance for the caliper.

Even with that being said, anything can be done if you put your mind to it...

Drilling the stock disc will shave some weight off the rear and is probably the easiest thing to do.

lockard666 · « **Reply #27 on:** April 17, 2011, 11:11:38 am »

hey "thelowmax"... i know this thread is months old, but i wanted to see how this worked out for you... i have a '75 750k & a no-title '76 750f parts bike($60, i couldn't pass it up)... anyway, i am looking at how to put the rear disk setup on my K model... the brake pedal pivot looks to be in an entirely different location on the frame... i'm pretty sure i'm gonna have to cut it off of the f frame & weld it to the k frame.

evan77 · « **Reply #28 on:** April 18, 2011, 07:07:58 pm »

Greetings,

I believe this might be my first time posting here but I thought I would share my setup. It is off an early 80's F model. I did not have to cut or weld anything although I am not opposed to doing so. It is argued by some, earlier in this "old" thread that it is big and clunky but I must say it works excellent and I am very pleased with it.

I fabricated a bracket out of 1/4" aluminum to mount the master cylinder to the frame via bar clamps. There is also a custom angle attached to the top of the swing arm to secure the caliper stabilizer.

I flipped the original splined pedal pivot so the arm pointed downward. I threaded a bolt through the arm or tab and this is what actuates the master cylinder push rod.

Here is how I solved the problems with the stock front brake setup. Nissin calipers from a 2004 CBR mounted with custom brackets I fabbed up. The rotors up front are also from an early 80's F model. Works excellent and is worlds apart from what was on there before.

Hope this helps!
Hopefully the pictures work.

Evan

thelowmax · « **Reply #29 on:** April 21, 2011, 05:36:29 am »

I really appreciate all of your input guys. You never fail to open my eyes. But having bought yet another basket case, my focus is in another place now. My bike stops on a dime and all that extra work time can be put to better use. Thanks again.

754 · « **Reply #30 on:** April 21, 2011, 08:54:59 pm »

Found a light disc today.
Stock Kawi, probably offroad.
3.2mm thick.. I think it is oK for drags and normal street use..
cant weigh accurately on my scale but looks like 1.5ish lbs, without centre spider/adapter. black oxide finish
250mm, or about 9.9inch
part #on it was 4180-1188
That is probably as light as you will find in a steel disc,

meme · « **Reply #31 on:** May 03, 2011, 06:53:49 am »

Quote from: evan77 on April 18, 2011, 07:07:58 pm

Greetings,

I believe this might be my first time posting here but I thought I would share my setup. It is off an early 80's F model. I did not have to cut or weld anything although I am not opposed to doing so. It is argued by some, earlier in this "old" thread that it is big and clunky but I must say it works excellent and I am very pleased with it.

I fabricated a bracket out of 1/4" aluminum to mount the master cylinder to the frame via bar clamps. There is also a custom angle attached to the top of the swing arm to secure the caliper stabilizer.

I flipped the original splined pedal pivot so the arm pointed downward. I threaded a bolt through the arm or tab and this is what actuates the master cylinder push rod.

Here is how I solved the problems with the stock front brake setup. Nissin calipers from a 2004 CBR mounted with custom brackets I fabbed up. The rotors up front are also from an early 80's F model. Works excellent and is worlds apart from what was on there before.

Hope this helps!
Hopefully the pictures work.

Evan

Even77 or anyone:

- what frame do you have and did you use the swingarm from that same frame?

-i have a cb550 will the disc brake setup from the 750SS or your model work on my cb550 swingarm?

-are the axle and spacers the same size? i found that 750 axle is 20mm but not sure if they are all the same.

-can the cb550 wheels be used? i want to keep the spoke wheels.

i already have the rear sets mocked up and have space for the master cylinder.

thanks for your help

evan77 · « **Reply #32 on:** May 05, 2011, 01:20:51 pm »

meme,

it is a 1977 cb750k and it is the stock swing arm. like i stated above, i had to fabricate an angle to attach to the top of the swing arm to secure the caliper support bar.

i will preface this response with the disclaimer that i do not have much experience with the cb550.

while i cannot say for sure that this set up will work on your cb550 i can say that most anything will work if you have enough patience and skill to make it so. i would assume that our axles are the same diameter but if yours is indeed different it would probably be a smaller diameter. if this is the case you could make up the difference between caliper bracket and axle with the correct size machined bushing. it may also be necessary to machine the correct size spacer but again, it is something i would have to look at first hand to say for sure.

as for your stock wheel, does it currently have a disc brake. i would venture to guess it does not or you would not be interested in this swap. therefore you more than likely have a drum brake style rear hub. again, i suppose this could be modified to work with a disc brake system but in my opinion your time and efforts could be better spent doing something else. ideally you would want to find a wheel that you could actually bolt a disc up to. you should be able to find a spoke rear wheel that has a disc type hub.

good luck and let me know if i can answer any other questions.

evan

ps. just a thought, if you want to stay with spoke wheels why not keep your stock setup? there is nothing wrong with a properly adjusted rear drum brake.

mycoal · « **Reply #33 on:** May 19, 2015, 06:10:15 pm »

Quote from: thelowmax on November 22, 2010, 10:13:33 am

I saw the bike, and spoke to the guy for about 15 minutes. Then, the guy wouldn't sell for the price he was originally asking because I told him I really only wanted the rear tire and braking system (shouldn't the price go down?). He immediately put the price for the entire bike on just what I wanted. Then he said I could take the stuff off myself. When I said I would take the whole bike, his price went through the roof, like he was selling each part individually. I offered the original price for the whole bike and he laughed. I just turned around and walked away. As I did, he followed saying, "don't be like that. Let's work something out". As I continued to walk away I thought to myself, "I don't want to have anything to do with this guy's messed up karma".

So, now I'm wondering... Anybody got a Supersport spoked rear tire with a disc rotor they want to part with?

It was because you were going to leave him with a parts bike if you took the rear. So he'd have to sell it @ parts prices. Starting with you first. You're bad at buying stuff. If its a great deal just give them the cash, load it up and take off like a bandit.

thelowmax · « **Reply #34 on:** May 21, 2015, 03:17:54 pm »

Quote from: mycoal on May 19, 2015, 06:10:15 pm

Quote from: thelowmax on November 22, 2010, 10:13:33 am
I saw the bike, and spoke to the guy for about 15 minutes. Then, the guy wouldn't sell for the price he was originally asking because I told him I really only wanted the rear tire and braking system (shouldn't the price go down?). He immediately put the price for the entire bike on just what I wanted. Then he said I could take the stuff off myself. When I said I would take the whole bike, his price went through the roof, like he was selling each part individually. I offered the original price for the whole bike and he laughed. I just turned around and walked away. As I did, he followed saying, "don't be like that. Let's work something out". As I continued to walk away I thought to myself, "I don't want to have anything to do with this guy's messed up karma".

So, now I'm wondering... Anybody got a Supersport spoked rear tire with a disc rotor they want to part with?

It was because you were going to leave him with a parts bike if you took the rear. So he'd have to sell it @ parts prices. Starting with you first. You're bad at buying stuff. If its a great deal just give them the cash, load it up and take off like a bandit.

I think you missed the point. I was going to buy the whole bike and agreed on a price but when he realized I was only interested in the rear wheel and braking system, he decided that it was worth more and continued to negotiate. I was the bird in hand. He opted for the two in the bush. I never felt better about a deal in my life. Ironically, now I'm not even interested in the rear brake concept anymore.

Let's talk about pods.

SOHC4 Cafe Racer Fan · « **Reply #35 on:** May 21, 2015, 03:37:10 pm »

No, let's talk about oil!

thelowmax · « **Reply #36 on:** May 24, 2015, 02:04:35 pm »

Quote from: CB750 Cafe Racer Fan on May 21, 2015, 03:37:10 pm

No, let's talk about oil!

I would sooner tell my wife how sexy her sister is.

dusterdude · « **Reply #37 on:** May 24, 2015, 02:38:00 pm »

Let us know how that turns out

Rookster · « **Reply #38 on:** May 30, 2015, 04:43:01 pm »

Here is the Hurst Airheart set up mentioned earlier in the thread. It is a drum brake Lester rear wheel that has been converted to a disk. A shorter brake line is on the way.

Scott

thelowmax · « **Reply #39 on:** June 03, 2015, 05:34:59 am »

Was the conversion from drum to disc part of the kit, or did you just "make do"? Looks great. But the snaking brake line IS pretty funny.

Rookster · « **Reply #40 on:** June 03, 2015, 06:43:03 am »

There was a kit offered by Hallcraft that used Hurst Airheart components.

I basically replicated the kit. The disk carrier was designed by me and made by emachineshop. I sourced a spacer and had it bored to 20mm to fit the CB750 axle. The rear disk is a cast iron ap Lockheed that was used on Triumphs, Nortons, and some Ducatis in the 70s. I used the kit as a template. The disk carrier mounts through the hub from the sprocket side and has a bearing in it. I am still testing the setup and will tweak it as need be. The brake line has been changed. I will update this post with a new picture.

Scott

MCRider · « **Reply #41 on:** June 03, 2015, 06:49:55 am »

I remember that kit, pretty slick that you've brought it back to life. the carrier was the hard part?

SOHC4 Cafe Racer Fan · « **Reply #42 on:** June 03, 2015, 07:50:04 am »

Nice! Now crank them out in quantity for us poor schlubs.

Tintop · « **Reply #43 on:** June 03, 2015, 11:53:33 am »

That's basically the kit that Cycle X offers now, just with a more modern caliper.

http://www.cyclexchange.net/Wheel%20Page.htm (about 1/2 way down)

MCRider · « **Reply #44 on:** June 03, 2015, 01:23:42 pm »

Quote from: Tintop on June 03, 2015, 11:53:33 am

That's basically the kit that Cycle X offers now, just with a more modern caliper.

http://www.cyclexchange.net/Wheel%20Page.htm (about 1/2 way down)

Scrolling down further, looks like they will offer the brake from their roadracer, a more petite version, than the chopper setup.

Tintop · « **Reply #45 on:** June 03, 2015, 01:46:34 pm »

The road race version uses a Talon hub I think, so different disk. The 'kit' works with the CB750 rear drum hub, same as was originally used on Samauto.

SOHC4 Cafe Racer Fan · « **Reply #46 on:** June 03, 2015, 02:52:48 pm »

Quote from: Tintop on June 03, 2015, 11:53:33 am

That's basically the kit that Cycle X offers now, just with a more modern caliper.

http://www.cyclexchange.net/Wheel%20Page.htm (about 1/2 way down)

Unfortunately, they've been out of stock for the better part of a year or more.

Rookster · « **Reply #47 on:** June 03, 2015, 05:07:52 pm »

The CycleX kit is very nice. I wanted something that would use 70s parts so I went a different direction. The CycleX kit shows the cost of producing something like this for sale as a kit. It also doesn't include the master cylinder, mount, linkages or brake lines so add another $150-$200 to the price. I'm not entirely happy with the 3/4" Hurst Airheart master cylinder and may be replacing it with something better but still 70s. Here's an updated pic with the shorter line installed.

Scott

MCRider · « **Reply #48 on:** June 03, 2015, 05:49:53 pm »

Very nice Rookster.

scottly · « **Reply #49 on:** June 03, 2015, 07:10:03 pm »

Quote from: Rookster on June 03, 2015, 05:07:52 pm

I'm not entirely happy with the 3/4" Hurst Airheart master cylinder and may be replacing it with something better but still 70s.
Scott

My bike came with a 5/8" Grimeca rear master, and foot controls identical to yours, Scott. I see that Cyclex has a very similar looking master, including the "push" style lever that mine had originally.

News:

Author Topic: rear disc brake swap (Read 16343 times)