Author Topic: Better braking: Caliper Upgrade? (Read 13573 times)

scartail · « **on:** October 06, 2009, 12:41:48 PM »

I was researching ideas on how to make an adpater plate for my hawk caliper, and came across this.

http://www.stotfoldengineers.co.uk/Stotfold_Engineering_blog/2009/09/10/honda-cb750-four-sohc-part-2-the-brakes/

Basically, taking a moderning caliper (I'm assuming upgrading the m/c, as well), and slapping it on the fork, via adapter plate. Might be better than dual rotors (with older calipers). Caliper for modern sportbikes are cheap.

Has anyone considered doing/has done something like this?...

Bodi · « **Reply #1 on:** October 06, 2009, 01:06:45 PM »

The problem is clearance to the spokes. The stock wheels have very little clearance to the stock caliper, and there's no easy way to increase it, the disk is pretty close to the fork as well. Every modern caliper I've looked at is quite deep behind the disk, needing room for the backside pistons.

voxonda · « **Reply #2 on:** October 06, 2009, 01:10:39 PM »

+1

Been looking for a relative easy swap for people who want something like that, you will need some modern calipers like the one in the pic, that grabs on the outside of the disk. The 'old' lockheed or Grimeca are too fat and won't fit without 'major surgery'.

Rob

fishhead · « **Reply #3 on:** October 06, 2009, 02:24:29 PM »

If I had a complete set of 750K forks, I'd be making kits for the 750 K's.

I have been making brake kits for other models for years. The most popular is the XS 650 by far. Out of the 100 or so kits I have made so far, 80-85 of them were for the XS 650.
Most aftermarket calipers are usually thinner on the inside (spoke side) than the OEM calipers are and can be used on more applications that need the extra spoke clearance.

Heres a 77 XS 650 front end with dual ISR twin piston calipers, Brembo discs

And the 310mm discs on my Dunstall (GL 1000 front end), they weren't quite big enough, so they were replaced with a set of 330mm discs. Same 6 piston calipers were used.

http://www.fishheadbigbrakes.com/

voxonda · « **Reply #4 on:** October 06, 2009, 02:31:10 PM »

Looking good, fishhead!
A few of my customers want to use the OEM fork with other calipers and no further hassle. I use the F2 or DOHC 35 forks so it is easier to adapt other calipers, but still it is hard to use a spoked wheel. Shim out the disk, mill the rear of the caliper, just a few millimeter here and there. With a cast one no problem.

Rob

moham · « **Reply #5 on:** October 06, 2009, 02:45:48 PM »

Fish, I think you would clean up around here if you were selling 750 adaptor kits...

davesprinkle · « **Reply #6 on:** October 06, 2009, 02:46:01 PM »

Want better brakes? Get:
1. A larger diameter rotor.
2. A dual-action caliper.
3. A set of good pads.

Here's a pic of the brake on my 400. Marzocchi fork from Ducati Pantah, 330mm disk from CBR929, Brembo caliper from Ducati Monster. I fabricated a hub to carry the rotor and a bracket to carry the caliper.

As others have mentioned, the biggest problem is finding room to clear the spokes. (This clearance issue is why the OE calipers on spoked wheels are usually single-action. As an example, see the recent Ducati classic-styled bikes with spoked wheels.) I addressed the problem by running the disk as close to the fork leg as I felt comfortable (1.5mm) and by building up the wheel with an all-inner lacing pattern.

turboguzzi · « **Reply #7 on:** October 06, 2009, 02:46:45 PM »

scartail,

Besides spoke clearance, another problem with the setup you show is that modern multi piston calipers have very narrow pads so they'd sweep a very small area of an original SOHC disc. kind of dumb IMHO.

The SOHC forks have the extra problem in that they dont have the typical twin ears to bolt a caliper (or adapter like in the XS/GL forks) so the adapter plate has to be quite complex. see here:

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

In any case, even if the original sohc calipers suck, I feel that those super modern calipers are out of place in a 70's honda. knowing the superb performance that period Grimeca's, Brembo's or Lockheed can supply, not even really needed. I cant stop my honda on its nose with my swap meet brembo's.

davesprinkle · « **Reply #8 on:** October 06, 2009, 03:54:19 PM »

Hey Turboguzzi, I'd love to see a pic of your period Brembo calipers.

turboguzzi · « **Reply #9 on:** October 06, 2009, 03:59:31 PM »

Quote from: davesprinkle on October 06, 2009, 03:54:19 PM

Hey Turboguzzi, I'd love to see a pic of your period Brembo calipers.

check the link above

fishhead · « **Reply #10 on:** October 07, 2009, 05:46:35 AM »

Quote from: turboguzzi on October 06, 2009, 02:46:45 PM

Besides spoke clearance, another problem with the setup you show is that modern multi piston calipers have very narrow pads so they'd sweep a very small area of an original SOHC disc. kind of dumb IMHO.

The stock CB discs are whats concidered a "wide band" disc. They use the height (top to bottom)of the brake pad to make contact with the disc. The newer style are concidered a "narrow band" disc and use the width (front to back) to make contact with the disc.

Using a newer caliper on an old disc can be done but its kinda like "half-a$$-ing" it, in my opinion. When using the newer components, disc and calipers, another added benifit to better braking is you also get better handling through less unspung weight . On my GL front end (when it had the 310mm's) I lost about 6 lbs off the front end (over the stock GL discs and GL calipers) and the difference in handling is very noticable. I didn't weigh the 330's prior to putting them on the bike.

The dual disc XS 650 kit pictured above also weighs less than the single disc set up that it replaces.

My kits are a bit too modern for some to put on their old bikes and they aren't everyones cup of tea.

fishhead · « **Reply #11 on:** October 28, 2009, 12:33:36 PM »

Quote from: fishhead on October 06, 2009, 02:24:29 PM

If I had a complete set of 750K forks, I'd be making kits for the 750 K's.

I finally received a set of forks for the 750 K (thanks, JS550).

I made a "prototype" using a Tokico 2 piston caliper and 320mm disc. The caliper bracket is made up with scraps of aluminum that I had and it should be 1 peice instead of the peiced together bracket shown.

I may make 1 dual disc set with the calipers and discs pictured, but I really doubt that I'll be making any kits for the K. In my opinion, the caliper bracket would need to be 1 peice and I would need a peice of aluminum 1 inch thick X 8 X 4 and most of that would be machined away. Big chunks of aluminum cost money and so does machine time. I would also need to make/modify all the bolts to work with this set up. All of this adds to the total cost of the completed kit, making this kit so expensive it probably wouldnt be viable.

I tried different discs with different offsets but the large bolt mounting boss on the fork for the swinging caliper mount on the K gets in the way. With smaller diameter discs that had more offset, the caliper bracket would be too thin in the boss area (the disc would be on the outside of the boss) and I would then require a chunk of aluminum about the same size as above, but 2 inches thick instead. Smaller discs with the same off set as the 320mm would have the calipers hitting the spokes. The 320mm disc pictured is about 1/4- 3/8 from the boss (the allen bolt that is used in the large boss had to have its head shaved down for disc clearance).

The only calipers I could use would be the type of calipers shown (2 outer pistons) due to the clearance of the spokes. I tried to use the ISR calipers (pictured on the XS 650 kit above) as the insides are alot thinner than OEM calipers, but they hit the spokes also. A Lester wheel would open up the options to different calipers.

oldfett · « **Reply #12 on:** October 31, 2009, 10:22:14 PM »

This may seem naive as I don't have my bike to look at right now but couldn't you just turn the fork tube around and mount the calipers on the back? The biggest problem I see with that is that the drain bolt might be in the way, but you would have a much easier bracket to construct from that direction, I would think. Again not sure how well that would work, if at all.

fishhead · « **Reply #13 on:** November 01, 2009, 06:03:57 AM »

Either way the big boss on the leg would be in the way. The caliper bracket would be the same if mounted like stock or if the forks were swapped from side to side.
I thought about mounting it reverse of the way it is mounted (big boss on opposite side of fork leg as the caliper), but I feel it is stronger with the big boss on the same side of the caliper and having the small bolts acting as "centering" (keeping the caliper from moving).

6adan · « **Reply #14 on:** November 01, 2009, 06:21:40 AM »

fishhead does that Brembo disk bolt directly to the GL wheel?

fishhead · « **Reply #15 on:** November 01, 2009, 06:47:23 AM »

The Brembo discs pictured are on a XS 650 wheel and front end.

Most of the time I have to modify discs to fit on the application I am fitting them to.

Sheik Yerbouti · « **Reply #16 on:** December 07, 2009, 09:05:45 AM »

Bump for progress.

XN · « **Reply #17 on:** December 07, 2009, 08:42:24 PM »

I have the disc part all sorted out, just waiting on some pieces to get the caliper mounted

MasterChief750 · « **Reply #18 on:** December 07, 2009, 10:22:22 PM »

watching in interest

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Author Topic: Better braking: Caliper Upgrade? (Read 13573 times)