Author Topic: Dual disc question - in front or behind the fork leg? (Read 13368 times)

bikebitzofvt · « **Reply #25 on:** July 11, 2009, 11:05:22 PM »

2 more questions:

~any great pads out there for the old calipers? In my opinion tuffStop and Vesrah pads are crap. EBC only lists their standard pad, Braking lists nothing. I'm thinking EBC HH or green compound. I have some contacts left there, I'll try calling them on Monday. I'll let ya'll know the results.

~Will the 77 550F dust seals fit my fork legs in lieu of the gators? The rusty fork ears and boots and all related extra uglies will be coming off when I startthe front half of this bike's conversion.

And no, I will not be the flickability test dummy - I wanted my bike to turn quicker so I went with 1" longer rear shocks. Jack the back up, more weight on the front.

Keep the shiny side up!
Tom

Maxacceleration · « **Reply #26 on:** July 11, 2009, 11:28:10 PM »

As fishhead says, there is a lot of work to run duals, and behind.
Also the calipers are behind the steering axis, thus the decreased effort for steering.

754 · « **Reply #27 on:** July 12, 2009, 09:08:26 AM »

LordMP, I think you are enough of a racer, that you will EASILY notice the difference.

I think the correct name of the steel piece is,
INVERTED FLARE SEAT... might be wrong

I dont think if the line is exiting caliper at 12 0clock, that you will need to use the bleeder screw as much, as the air will run up the line.

I dont consider this job a lot of work, a bit of work, but easily done in a few evenings. Easier than a swingarm swap or a custom rear disc, IMO

Bwaller, just cut a piece of aluminum or steel to put in the caliper while bleeding, drill a hole to hang it on the wall or put in your toolbox.

To the OP, if you are making your own lines up you might want to consider going thru the steering stem to a tee, with straight fittings or 45s coming off to caliper .. for best look (can you tell I am not a fan of Banjos?)

fishhead · « **Reply #28 on:** July 12, 2009, 09:46:27 AM »

Quote from: 754 on July 12, 2009, 09:08:26 AM

I think the correct name of the steel piece is,
INVERTED FLARE SEAT... might be wrong

I'm not sure what Honda calls them, but the same type Galfer things (that convert the concave inside area to convex ) are called Conic Inversors, or at least thats what Galfer calls them. The Galfer things are little "pill" looking things with a convex on both ends and a hole in the middle.
Most of the Galfer female fittings (like what would be used to hook up to the stock hard line- from the caliper- to the braided brake line) have a concave end and need the inversors to get the the convex sealing area correct.

Industrial Rat400f Killer · « **Reply #29 on:** July 12, 2009, 10:09:53 AM »

OK, just to clarify.
The little convex washer that is in the hole where the brake line is can be removed and a banjo bolt can then be placed in that hole?

I though that would fix my ill positioned hose but wasn't sure removing that washer was a good idea. I used new ss brake lines when changing my M/cylinder to a more modern design but when I figured everything out I didn't realize the ss brake line would be a weird fit at the caliper. I've been brain storming ideas but I wasn't sure which was the best.
It's hard to tell in the pic but my line is pretty close to my front tire. This is caused by the built-in fittings on the Russell brake line.

Bill/BentON Racing · « **Reply #30 on:** July 12, 2009, 10:31:53 AM »

The dust seals should fit fine,MCRider made a lot of sense,and yes you can feel it on the track,try it you will like it and believe,Maxacceleration your bike is beautiful,what a sweet looking ride.I raced the 590cc Yosh kitted bike from 1985-87,my buddy Glenn Cooper ran it in 88 and 89. Bill Benton,

lordmoonpie · « **Reply #31 on:** July 12, 2009, 11:48:40 AM »

Quote from: 754 on July 12, 2009, 09:08:26 AM

LordMP, I think you are enough of a racer, that you will EASILY notice the difference.

You might be right 754 and MCRider has hit the nail on the head - I've never had the two setups on the same bike to compare on track. Come to think of it, it's only the CB350 K4 I've ever raced with forward calipers and now the 750 has them so it will be interesting to see if I notice say the difference between the 750 and the CB497 with the rearward caliper.

That's the best thing about fiddling with stuff like this - it's just a hoot finding out by trying stuff, what really happens and what the effect is. Still, I like my 750 forward facing calipers just for the look. You gotta admit they're kinda cute

voxonda · « **Reply #32 on:** July 12, 2009, 02:35:21 PM »

You will notice it once it starts to shake it's head, then you wish you had them mounted rearwards.

bikebitzofvt · « **Reply #33 on:** July 12, 2009, 03:05:16 PM »

I put a cruddy old caliper in the vise to experiment with. I drilled the "conic inverted flare seat inversor" with a 4.5 mm bit. Sent in a 5 x .8 tap, 2 turns and that evil little chunk of steel pulled right out of the caliper! Now the banjo and line end fits perfectly. Just waiting for gl1000 rotor bolts and new caliper seals, then I can get this project rolling!

Max - I too adore your bike. It's my current desktop background (for inspiration)!!

Now for some quality brake pads - I'm going to call a contact at EBC tomorrow and ask if they would do a run of fa13's in green stuff. I'll keep y'all posted on that...

turboguzzi · « **Reply #34 on:** July 12, 2009, 03:38:29 PM »

Followings LordMP's post, I did have both set ups on the same bike.

started with calipers behind for function and looks, but after I got one race (and one disc) ruined due to binding in one caliper, I reverted to calipers in front.

I believe now that the calipers behind fork, even if better in theory, might create a dragging/binding problem, specially when the inner pad wears out. will try to do a sketch to explain why.

Did all of last year with calipers in front without problems and sorry to dissapoint, but to cant say that I noticed a difference in steering effort. I agree that if you run without a steering damper, then calipers in front might be worse, but I do use one.

Now I am running a setup with small brembo's (behind the fork BTW), so almost forgot about the whole dilema. They work so well it's another world really.

For best (read stoppie inducing ) power go with ferodo platinum's, Vintage Brake's got them.

TG

bistromath · « **Reply #35 on:** July 12, 2009, 03:41:24 PM »

turboguzzi: do you have more information on your setup, bracket fab, mounting, etc?

turboguzzi · « **Reply #36 on:** July 12, 2009, 03:45:19 PM »

here
http://forums.sohc4.net/index.php?topic=44616.msg470555#msg470555

Have also a .dxf / .ai file for the bracket if you need.

TG

Maxacceleration · « **Reply #37 on:** July 12, 2009, 05:53:37 PM »

Interesting turboguzzi.
I appear to have a slight amount of drag also. We may be digging back into my brakes just to eliminate any unwanted drag.
Drag, besides ruining discs potentially, can overheat the motor and take away acceleration in a small motor.

My bike seems to coast ok, but pushes around in the garage like a pig...

Thanks for the compliments on the old scoot y'all...

Bill/BentON Racing · « **Reply #38 on:** July 13, 2009, 04:36:47 AM »

Dragging brakes,any,should be fixed!Besides ruining discs,pads,etc and slowing you down dramatically,they will build enough HEAT to put you on your butt quick!!Find the problem and fix them and yes I probably put as much time in getting mine right as anything else on the race bike,it last ran @Roebling Road in 1989,it rolls as good today as it did then,alignment on the second caliper crucial,I had to shim bracket,original caliper and leg shold be no problem.Try loosening one caliper or other and find which has problem,use whatever # fluid you want 3,4 or DOT 5,I prefer Dot 5 for lots of reasons,but one nice one is your bike will roll easy 25 yrs later,try that with 3 or 4!Bwaller another nice ride!Turboguzzi,you are still racing yours-Cool,I am going to check your link,want to see more of your bike.What's inside that engine?Be safe and fix any dragging brakes!Good Luck,Bill Benton

turboguzzi · « **Reply #39 on:** July 13, 2009, 02:12:54 PM »

hei bellcow

I also spent a long time setting the calipers up so the pads are really parallel to the discs by shimming, filling, adding washers, you name it.

Indeed, the set up is not symmetrical either....

What was worse was the deterioration in alignment when the pads wore, eventually one pad cocked in the caliper and dragged enough to finish a disc by overheating in just one race.

So in all, the double disc set up can be made to work but those "flag" calipers (as they call them in italy) require attention. It's very easy to have the static pad wear thin in just one side so the metal backing touches the discs.

Really happy now with the brembo set up which lets the pads work as they should. If you are not going for a concours restoration, I'd reccomend it.

will send you a pm with some links to my bike's developement.

Max, best way to identify drag is to have the fron tin the air, grab the brakes and release. front wheel should be prety easy to rotate.

TG

lordmoonpie · « **Reply #40 on:** July 14, 2009, 04:39:59 AM »

TG's right - with a damper on the bike I'm not sure you'd notice any effect from the front facing calipers and lets face it, racing one of these without a damper probably means you can't push it as far. It's true on my VTR so will cerainyl be the case on these old frame with hinges in the middle!

Like TG I'm a huge fan of aftermarket calipers but in my case it's the AP racing classic ones - well he's Italian and I'm British so it's only fair we should support our country's economy

I kept stick Honda on the CR for show purposes but will almost certainly swap them for much more powerful APs in the future and then the whole debate goes away I guess...

turboguzzi · « **Reply #41 on:** July 14, 2009, 11:46:07 AM »

Support Italy's economy?

By buying in an autojumble a pair of used Brembo calipers for 20 euros?

Hope Italy's got a better backup plan to get out of the crisis.....

:-)

Forgot to mention also the HUGE unsprung weight savings with Brembo's/AP's

fishhead · « **Reply #42 on:** July 14, 2009, 11:55:03 AM »

Quote from: Iggy on July 10, 2009, 02:43:49 PM

Quote from: fishhead on July 10, 2009, 02:31:23 PM
Well, I'm not trying to insult any one, but I CRINGE every time I see a bleeder thats not pointing up.

When someone puts in all the effort to dual disc their bike (modifying the speedo drive plate, getting the 2nd caliper mounted and correctly lined up, longer disc bolts,etc) and then get "befuddled" by trying to remove the conic inversor that is under the hard line (where it seals), I just shake my head. Out of all the things that need to be done to convert to dual disc, removing the pressed in conic inversor, isn't hard by comparison.

If you have the caliper apart, put a shortened nail throught the conic inversor (I dont remember the size of the nail) and the head of the nail will pull the inversor out when it is pulled with vice grips. You can tap on the vice grips to help with removing the inversor.

Didn't work? Still have the caliper apart ? Run a thread tap through the inversor and then put a bolt through a washer and tighten it up. It will pull the inversor out. Using a longer bolt and a socket (instead of a washer) works good too.

Didn't pull your caliper apart? Run a wood screw into the inversor and use a chisel/screwdriver with a hammer(on the wood screw) to knock the inversor out.

Have to reuse the inversor to put the hard line back in the "other" hole?
Put it in your drill and use a file to remove any burrs that may have happened.

Not using the hard line? Chuck the inversor in the trash as it is not needed when removing the hardline and going to a one peice line.

Rant Over.

Bring the rant Fishhead! I had no idea how to get it out, reversed and set up and didn't find anyone talking about it.

From the noob perspective my biggest worry was destroying things I didn't need to destroy from lack of knowledge. Even with the board and FAQs I killed a few things in the process.

If you could knock out some pics of the process and add them to the dual brake FAQ I (and more than a few others I'm sure) would be pretty thankful

Heres 2 pics on how to remove the conic inversor.

Pic 1

1) screw a wood/sheet metal screw in to the inversor
2) put the blade of the screwdriver/chisel on the head of the screw and hit the handle of the screwdriver to drive the inversor out.

Pic 2 shows what the inversor look like when they are removed.

Use a good screw with a heavy head. The first screw I used (pictured on the caliper) had a thin head and the head of the screw broke off with the first whack of the hammer. I replaced it with the screw shown on the removed conic inversor and it came right out.

ev0lve · « **Reply #43 on:** July 14, 2009, 12:48:38 PM »

Thanks for that! Looks about as easy as it gets.

Why do I have Sonic Reducer in my head except I'm singing it Conic Inverser?

Randakk · « **Reply #44 on:** October 14, 2009, 11:41:59 AM »

Quote from: Maxacceleration on July 11, 2009, 11:28:10 PM

As fishhead says, there is a lot of work to run duals, and behind.
Also the calipers are behind the steering axis, thus the decreased effort for steering.

Maxacceleration:

Beautiful bike above!

Can you tell me the source of your front fender? I'm looking for one similar. Thanks.

Toxic · « **Reply #45 on:** October 14, 2009, 01:17:47 PM »

All the theory is sound but for the average rider it's about looks.

For myself, if I wanted it look like every other bike out there I'd put it behind the fork.

The caliper in front is one of the most distinctive features of the bike.

Ultimately it's your decision.

News:

Author Topic: Dual disc question - in front or behind the fork leg? (Read 13368 times)