Topic: Forks for dual front brakes '74 CB550 - New Member

[BumpPass68]

I just started my first CB build and I would like to swap my forks so that I can go with dual brakes up front. What is the easiest and most available forks to use? I have searched threads but I cannot find what I am looking for. Can someone help a newby and point me in the right direction or recommend a thread?

[Scott S]

 If you have stock CB forks, you don't need to swap. The lower fork leg has the mounts cast in for another caliper.

 Search "dual disc conversion".

[BumpPass68]

Thanks for the quick reply Scott. I just picked the bike up on Saturday and have spent the time since unfreezing the motor and getting spark to all 4 cylinders. So, I didn't even look at the forks yet. Haha. Was getting ahead of myself a little.

[BomberMann650]

Subscribed

How does dual disc effect the speedometer attachment?

[SOHC4 Cafe Racer Fan]

You will need another mount bracket, caliper and rotor.  In addition, you will need to either obtain longer rotor bolts to mount the second rotor Or you could chamfer the mounting holes, so that the original bolts can span the distance.  You will also need to modify the speedo pickup bracket so that it can fit with the wider rotor/hub/rotor assembly.

You can buy a whole kit of extra caliper, thinned rotors with chamfered mounts, etc. from Godffery's Garage  http://www.vinmoto.org/gallery/v/VinMoto-Garage/album03/Godfferys-Garage-123/Parts+and+service/Complete+Twin+Disc+kit/

[BomberMann650]

I hope they have a brake caliper comes with chipped fading paint too.  It'd be a shame if it didn't match the look of the other side 

[alacrity]

And I did a little extra on mine - I moved the calipers behind the fork legs.  It lightened up the steering and made it all feel a bit "quicker" on turn in. I've noticed no decrease in stability, line-holding or any other similar issue. Either way, it can be a little tricky getting the hangers aligned perfectly with rotors -  you may have to grind some of the right fork leg bosses down a bit or shape the caliper hanger bracket a bit or both.  Compare the stand height of the bosses on your left (the one where the caliper is now) to your right leg.  On my bike, which may or may not have had the original legs on it when i got it, they were different.

[Bankerdanny]

You need a different front wheel also do you not? The Lester on my bike comes ready for a disk on the right side, but I don't recall mounting holes on the right side of the wire wheel on my '77 550K or my '74 550K project bike.

[Deltarider]

First check the right front leg actually has that mount.
Then, not to hijack this thread, although the stock front brake is not perfect (and that's an understatement) I was never tempted to fit a second disk brake. It's a hassle resulting in a lot more weight in the wrong place and spoiled looks. What I'm open to is a lighter, thinner and modern disk that is better in the wet and would fit the old system.

[Scott S]

You need a different front wheel also do you not? The Lester on my bike comes ready for a disk on the right side, but I don't recall mounting holes on the right side of the wire wheel on my '77 550K or my '74 550K project bike.

 No...the stock wheel is drilled all the way through. It just has a chrome cover on one side.

[DaveBarbier]

I too used the parts that Cafe Racer Fan linked too. Godffery is a member here and he makes good stuff.

And just like Alacrity, I did trailing calipers. I didn't notice any "quicker" steering, I think it's a placebo. In my build thread I have some info on installing my dual setup, if you feel like checking it out.



Regarding looks, I think it's an improvement.

[Scott S]

 At one time, a member here was making a speedo adapter. Somewhere on the site there's also a "how-to" to make or modify your own. **EDIT: I just saw the link above...that's the speedo drive I used **




 You'll also need longer bolts to make up for the added thickness.
 You may have to grind on the pad of the caliper to center it properly, and you have to "reverse" the centering screw.




 I could never get my dual disc conversion to work right. I tried everything to center the second caliper and I tried three different master cylinders of varying bore sizes.
 If you use a good stock (or David Silver Spares) master cylinder, rebuilt caliper, braided hoses and EBC pads and shoes, you'll have more than adequate brakes for a 550.
 If I ever look into upgrading brakes again, I'll look at lightweight rotors, dual piston modern calipers and a matching master cylinder. My .02.

[alacrity]

I too used the parts that Cafe Racer Fan linked too. Godffery is a member here and he makes good stuff.

And just like Alacrity, I did trailing calipers. I didn't notice any "quicker" steering, I think it's a placebo. In my build thread I have some info on installing my dual setup, if you feel like checking it out.



Regarding looks, I think it's an improvement.

Drilling the rotors helps offset some of the weight gained. Going to a bigger bore MC gives good lever feel and better modulation. Instead of what feels like wood, you have ... brakes.  More stopping power with less effort.  And the comment about adding unsprung weight is real. You will notice crappier handling because the lightweight (atf) fork oil and old saggy springs are gonna be overwhelmed by they extra pounds bouncing up and down. I went to a Racetech set up to counteract that, and it's pretty darned wonderful now.  And imho, not to be argumentative, but I noticed an immediate difference with the calipers flopped.  I guess it depends on how fast you're riding in and out of corners.  In the quick transitions in some of the tighter yet still quick canyons near here, the bike was definitely more responsive after the swap.  This caliper arms are pretty darn long... and the weight is not only put back but also DOWN (importantly) relative to the cg of the wheel itself. In aggregate, you have less (effective) weight to pick up from one lean angle to throw across center and get it to plant in the next opposite lean angle.  Find  (or create) a chicane and try back to back.

[BumpPass68]

I just found this link that explains some of the finer details of this conversion including the speedo situation. http://www.huelligan.com/cb550/dual-disc-brake-conversion

[DaveBarbier]

I too used the parts that Cafe Racer Fan linked too. Godffery is a member here and he makes good stuff.

And just like Alacrity, I did trailing calipers. I didn't notice any "quicker" steering, I think it's a placebo. In my build thread I have some info on installing my dual setup, if you feel like checking it out.



Regarding looks, I think it's an improvement.

Drilling the rotors helps offset some of the weight gained. Going to a bigger bore MC gives good lever feel and better modulation. Instead of what feels like wood, you have ... brakes.  More stopping power with less effort.  And the comment about adding unsprung weight is real. You will notice crappier handling because the lightweight (atf) fork oil and old saggy springs are gonna be overwhelmed by they extra pounds bouncing up and down. I went to a Racetech set up to counteract that, and it's pretty darned wonderful now.  And imho, not to be argumentative, but I noticed an immediate difference with the calipers flopped.  I guess it depends on how fast you're riding in and out of corners.  In the quick transitions in some of the tighter yet still quick canyons near here, the bike was definitely more responsive after the swap.  This caliper arms are pretty darn long... and the weight is not only put back but also DOWN (importantly) relative to the cg of the wheel itself. In aggregate, you have less (effective) weight to pick up from one lean angle to throw across center and get it to plant in the next opposite lean angle.  Find  (or create) a chicane and try back to back.

My rotors, the ones from the above link from Godffery, are drilled and also thinned so there is even more weight saving. I actually kept the 14mm MC and haven't felt any issues. I feel like I have great brakes for what they are.

Regarding the springs and oil being overwhelmed, maybe in your case, but I don't think I have issues with that. Steering is quick and precise and suspension up front feels really nice. If it's not obvious I have stock forks and internals with ATF.

I trust you that you perceive a difference whether real or not, and I haven't ridden with both calipers forward and also reversed so it's hard for me to discount your perception. But when I was doing the conversion I did a lot of research and there's much debate in the forums whether or not the conversion is merely aesthetic or actually functional. Many, including Bwaller who races, feels that the theory is sound but hardly noticeable. If anyone knows that Bwaller doesn't think this then please correct me. I don't want to put words in his mouth. I'm just going off memory from my research.

Either way, it's fun and looks great. I just wanted to let the OP know that there's debate on the subject of flipping the calipers.

[Bankerdanny]

You need a different front wheel also do you not? The Lester on my bike comes ready for a disk on the right side, but I don't recall mounting holes on the right side of the wire wheel on my '77 550K or my '74 550K project bike.

 No...the stock wheel is drilled all the way through. It just has a chrome cover on one side.

3 550's in 5 years and I had no idea.

[somesuch]

why not go with the GL1000 forks/calipers? stiffer forks, four bolt caps, no swinging stuff, uses stock 750 hub, looks period correct and bolts right in!

[SOHC4 Cafe Racer Fan]

With the GL1000, you'll also need the GL rotors since the calipers have different offset to the hub.

Also, you will need to respring the GL forks once finished since there is a VERY significant weight difference between a stock GL and CB550.

I used a GL1000 front on my CB750.

[alacrity]

You'll need slightly longer hub bolts too.  And once you have all the parts, the only thing requiring more than bolt on/bolt off to reverse the forks is re-bleeding and flopping the front fender (note that I bobbed mine, so it is only attached with the four center rivets,  allowing this reversal).  The steel support for the fender acts as a fork brace of course. And the fender does what a fender does, so IMHO it's important to keep that in place - perhaps especially with the dual disk setup and that extra weight wagging around ahead of you.  You don't want any extra harmonic wiggling to start making its way up the legs into the frame and back again ... Tankslappers SUCK.   

Truth is, I was gonna leave the calipers front-mounted.  I posted a pic on my FB page of the bike that way and a whole bunch of friends who are current and ex-roadracers and tuners messaged me telling me to do it.  I was very ready for the bike to be done but people I respect were all but yelling at me.  So i said "ok fine... It better be worth the trouble."  It was.  I thanked them. Ymmv

[RAFster122s]

To pull a wheel with the stock forks with dual disc will require you to pull the caliper off one side, no clearance for it to slide past.  I don't think you have to pull the caliper arm but you might.  Anyway, it is more steps and a little more involved to do it when you have dual calipers on stock forks.

There are several threads on other forks being fitted for modern two pot or four pot (piston) calipers. GSXR and R6 are the most popular and I think someone even did a CBR600 fork swap.
With those changes they often went to a 18 inch front wheel as well. The GSXR and R6 standard fork (not upside down -USD fork) can be done retaining the spoked wheels but expect to spend upwards of $800-1000 for just the fork conversion, not to mention the extra for the wheel and new tire.
Most will go with a wider rim in front and back using an aluminum rim from Sun or Excel to fit a little larger rubber. I like the stock sizes.
The R6 forks can be fitted with a top triple tree from a FZ6 that has handlebars, for a riding position where you aren't leaning forward as much.
Rear sets work best with cafe bars/clip on bars so, consider that as a possible road that changes the riding position as well.
COgnimoto sells a hub that can be used on the GSXR or R6 fork conversion.
You only need a modern big floating rotor (295mm and up) on one side for great braking, no need for dual discs with a modern fork and brakes.
The R6 conversion uses a CBR600 F2 rotor with the Yamaha R6 or FZ6 rotors that are two piston or four piston calipers, FunJimmy did a nice write up of his conversion with this setup. He did a lot of hub machining using the stock hub...300-450 to get it done usually...
If you have access to lathe and a machinist friend then your cost could be less.

Depends on how much you want to spend.  Initial toe into the pond of upgraded brakes is easiest with the stock twin caliper setup on stock forks. Racetech gold valve emulators, with new good springs, and upsized MC to handle the dual discs.  I think you can get FA31 pads in semi sinstered composition now...used to be only the organic pads. That helps improve braking as well.

Oh, the other thing you need to do is to install braided stainless teflon lines (Slingshot Cycle has them inexpensively) for the brakes. Shaun can hook you up with lines for a setup of single or dual caliper.

David

[somesuch]

True on the GL1000 rotors, they are a smaller diameter than the 750 as well....but they are cheap
The GL springs seemed OK for 190lbs rider, though rear shocks/springs have to match.

[RAFster122s]

Are the CB750 and CB550 rotors spaced at the same width? Would they be a bolt up affair to mate the CB550 hub and wheel with the GL1000 front end? Or do you use the GL1000 rotors and calipers on the cb550 hub or is it a CB750 hub that gives the proper spacing for the rotor with the GL1000 front forks and calipers.
The CB550 and CB750 use different lengths of swingarms for the caliper. Certain years used the same caliper I think...but it might be different I don't know... Others who know both bikes can chime in with clarification here if it isn't in a FAQ somewhere on the site...like in the FAQ area.

David

[somesuch]

I believe all of those hubs (CB550/CB750/GL1000) are the same.

You need to use:
 GL1000 forks and triples (not sure about the stem length for the 550; on a 750 it is a straight bolt on)
 GL1000 calipers/bolts/ and you'll need to figure out the brake lines
 GL1000 fender
 GL1000 rotors (they are smaller in diameter than the CB750) and bolts
 GL1000 axle/speedo drive/spacers
 GL1000 headlight ears or make some custom units