Topic: Cheapest way to throw a disk on the 550 rear?

[geoluv]

 ...while keeping a spoked wheel.  Cognate moto has the kit for $500.  Little steep.  I can find a 750 rear hub and use that right?  What else is involved in the diy option? 

[strynboen]

yes 750 f bikes parts fits over..but...the disc are as big as the rear hveel..think to make a adaptor to put in the brake bore..and weld it inn and put it in a lathe and machine aut for a adapter to a smaller disc..and a nice twin piston caliber....some modern 400-600 cc bikes have some nice parts..

[Bankerdanny]

It has to be a '76 F model hub. That was the only version of the 750 that had a spoked rear wheel with a disk.

You need the arm that holds the caliper, a rear brake master and you will need to fab up a bracket to attach it to the frame. You also need to fab up a stay arm for the caliper bracket. You will likely also need to make new spacers to center the wheel properly in the swing arm.

I can understand the appeal, I have thought about adapting the alloy wheels from an FT500 Ascot single for use on a CB550 as they are the right size and the FT was rear disk. That said, the stock drum is more than sufficient for the level of power our bikes make. If upgraded brakes are the goal I would spend my time and money on a dual front disk setup rather than a rear disk.

In the end, there is no "throwing" a rear disk on. It takes effort and fabrication.

[seanbarney41]

I would start measuring up dirt bike rears.  Most will not have a cush drive, though.  Much debate about whether that is an issue or not.

I would debate whether a disc rear is much of an improvement on a street bike.  If you are counting on the rear for big stopping power, you better practice, practice, practice!  The rear brake can get you into dangerous trouble.

Danny has good points.

[BomberMann650]

+1 not a bolt on job.
Rear drum works good at leveling the bike when applied with front brake.  Works real good for some gentle trail braking too (if thats your thing)

[nicks2319]

I'm in the middle of this on my 500. Going the 750f route. Hardest part so far is figuring out how to mount the master cylinder and make it work. That's the only thing blocking me. And the parts are getting harder to come by.

Probably gonna end up having to make a custom bracket to mount to the frame.

[nicks2319]

Peek this thread

http://forums.sohc4.net/index.php/topic,154456.0.html

[geoluv]

ok the reason i want disk rear is cause i ride in lots of traffic and when going very slow and snaking through traffic gentile rear braking with your foot is easier/lazier than braking with your hand and it keeps the bike level, or else you use the front brake and are always bobbing up and down especially since these forks collapse like a house of cards under any pressure.  also if you use the rear drums a lot in traffic like i describe they wear out fast.  not a big issue but disk pads last way longer.

i want disk pads for lazy foot braking in traffic. 

i do agree though that the stock braking on the cb550 is not just more than adequate but exceptionally well balanced.  one of the first things i did when i got my cb running was test hard braking and was surprised at how controlled it felt when slamming on both brakes

[seanbarney41]

sounds like you nee to fix your forks, not your brakes

try getting out of the city for a ride.  I feel bad for urban motorcyclists.  That #$%* sucks.

[slikwilli420]

Agree with Sean. If your forks dive like that you need to fix the issue, not change riding style.

A few options in order of cost, and oddly enough also ranked in effectiveness:

1. Add more preload to the springs you already have. This options sucks and is really only another bandaid.
2. Add progressive springs, which cost under $100. They are a good option but its a one spring fits all situation and depending on bike weight and your weight, you may not get much of the intended benefit. They will however, restore a more stock feel to your sacked-out 40 year old springs
3. Add straight rate springs and emulators from Race Tech. This package transforms the stock forks and requires only a few short hours of time. Even out of the box, they will be far superior to either of the other options and will run in the $250-300 range.

[geoluv]

i ride it out in hunterdon county nj and bucks county pa when I'm visiting my dad but this is my city bike.  I am in the market for a 848 evo or 998 as my country bike:) i'm also in the market for a '78+ 911sc hard top to hot rod with my dad. 

rebuilding my forks is on my list of things to do.  i have the seals and oil ready to go.  just deciding what mods i wanna do. 

i weigh 150lbs.  is that too light for progressive springs?  i want a confident but cushy ride feel the roads in nyc are very rough. 

new springs and emulators cost $250-300, but for just a few hundred more i could snag a gsxr front end if I'm patient and sell all my stock stuff.  but then i would have to decide what to do about the front hub...  i probably won't go that route just yet but i want to eventually because the gold tubes on the inverted forks would match the gold pinstripe on my tank and look soooo bad ass .  I'll probably just decide between progressives and emulators and try to snag a deal somewhere, maybe some used stuff who knows. 

[slikwilli420]

Progressive springs are probably OK. The way it was explained to me is that many times people will use enough preload to get their sag correct that they use up all the progressive part of the spring, which leaves you with a straight rate spring of unknown weight.

With straight rate springs and emulators, you have choices on spring weight and the emulator allows the fork to separate the compression and rebound damping actions so the damper rod in your forks does not have to do both. This is pretty much a set it and forget it deal.

If you go with USD forks (which I don't care for since the performance there needs to be backed up by a bunch of other stuff) you are looking at a few hundred for the forks, a few hundred more for the hub, a couple hundred more for the spokes and wheel, and at least a few hundred more for the correct offset triple trees. Its easily a 3x cost to the springs/emulators and unless properly tuned, will probably not yield wildly different results from the less expensive options.

[Bankerdanny]

I weigh 240 and ride in heavy traffic in Chicago all with time and don't have fork dive issues with my 550 and stock forks.

I run slightly heavier weight oil in mine (15wt), but at your size conventional 10wt fork oil should be fine.

[geoluv]

i though you could buy an entire front end and all you need to do is get a front wheel and the all ballz adaptor, what else is required to mate the steerer tube to the head tube?

http://www.ebay.com/itm/2005-2006-Suzuki-GSXR-1000-Front-End-Suspension-Forks-Calipers-Handle-Bars-Tree-/302175009964?hash=item465b08bcac:g:wasAAOSwux5YXZdg&vxp=mtr

^sometimes you can catch deals around that price that come with the front wheel.  just gotta be patient like i said:)

[Bankerdanny]

Adding the forks can be relatively cheap, but then you have to figure out how to adapt the matching rear wheel or spend $330 on the CognitoMoto front hub that allows you to use the Suzuki brake setup with a spoked wheel assembly.

[nicks2319]

GSXR swap is more involved than you're thinking.

[BomberMann650]

I weigh 240 and ride in heavy traffic in Chicago all with time and don't have fork dive issues with my 550 and stock forks.

I'm a 275# sack of beef myself.
Despise urban city traffic "riding".
Added an extra 15ml of 10 wt fluid to my forks.  To dampen the nose dive under (strategically) late, heavy braking.