Topic: Stock front brake vs. custom

[longshanks]

So I'm wanting to put the original front fender back on and I figured I'd also go back to the stock caliper since the PO mounted a dual-piston Tokico on there that is pretty sketchy according to what Hannibal was telling me in this old post of mine: http://forums.sohc4.net/index.php?topic=90438.msg1013389#msg1013389

Will I be seeing a big difference in braking performance with the stock caliper vs. the custom dual-piston set-up? what about adding SS lines to a stock caliper set-up? or are there aftermarket dual-piston calipers out there that grab the entire surface area of the 750 front disc?(my current set-up does not)

[TwoTired]

Depends on how you measure performance.  And, you haven't stated what your current performance is.

The SS lines help transfer all the hand lever pressure to the caliper.  I like this.
With the Cb550, it allowed me to squall the front tire, with a max hand pressure squeeze of the stock master cylinder lever.  If you are looking to operate the front brake with your pinkie finger, you sure won't be happy with the stock system even performing at its peak.

The stock SS front disc is not the best friction material, but it doesn't rust easily.
The stock Master cylinder doesn't provide the mechanical advantage offered by more modern master/lever arrangements.

I don't think the caliper is the main culprit in your dissatisfaction.  But then, there are no metrics by with to compare what you have now to whatever is changed.

The owner's manual has a description of how fast it will stop from a given speed.  But, it is not predicated on applied lever pressure.

I will note that where you apply pressure to the lever matters.  Farther distance from the pivot provides better mechanical advantage and more pressure developed in the hydraulic system.

Cheers,

[longshanks]

Depends on how you measure performance.  And, you haven't stated what your current performance is.

The SS lines help transfer all the hand lever pressure to the caliper.  I like this.
With the Cb550, it allowed me to squall the front tire, with a max hand pressure squeeze of the stock master cylinder lever.  If you are looking to operate the front brake with your pinkie finger, you sure won't be happy with the stock system even performing at its peak.

The stock SS front disc is not the best friction material, but it doesn't rust easily.
The stock Master cylinder doesn't provide the mechanical advantage offered by more modern master/lever arrangements.

I don't think the caliper is the main culprit in your dissatisfaction.  But then, there are no metrics by with to compare what you have now to whatever is changed.

The owner's manual has a description of how fast it will stop from a given speed.  But, it is not predicated on applied lever pressure.

I will note that where you apply pressure to the lever matters.  Farther distance from the pivot provides better mechanical advantage and more pressure developed in the hydraulic system.

Cheers,

Good info, what MC's can be used with the stock caliper with SS lines?

[Doctor_D]

You can use virtually any of the Brembo or Nissin mc's.  Something like this would do the job nicely. http://www.yoyodyneti.com/ProductInfo.aspx?productid=10.5393.51

What you want to pay attention to is the ratio between the mc piston and the caliper piston, as it effects feel and modulation.  See this description on Vintage Brake's website: http://vintagebrake.com/mastercylinder.htm

I'm using an 12mm Nissin.  It has an integrated brake-light switch, which allows the junction to be eliminated and the use of a 1-piece SS brake line.  Ferodo Platinum brake pads offer good feel and grip as well.

UPDATE: For a CB750, the front caliper piston is 1452mm2, and a 12mm mc is 113mm2, giving a final ratio of 13:1, right in the single-piston sweet spot.

[wedoo2]

I went with a new master cylinder and SS lines from Slingshot. for my 550.  $140

[longshanks]

i'm wondering if i can use the master cylinder on have on there now with the stock caliper if i choose to put it on. will it apply too much pressure to the caliper since its newer?

[grcamna2]

What MC do you have on there now...is that the one that needs to be rebuilt? the O.E.?

[Doctor_D]

14mm master cylinder piston is what you should generally look for as it has higher pressure than one with a larger piston all other things being equal. You don't want a hard feeling brake lever and you don't want one you can pull into the handlebars either.

rt

That may be the stock diameter, but it is nowhere near correct.

The CB550 had a 38.1mm piston. Using a 14mm MC gives a 7.4:1 ratio for a single piston caliper.  Using a 14mm MC will result in a wooden feel with an unpredictable lockup point.

The MC I linked higher up in the thread, at 11mm, gives and appropriate ratio of 12.6:1.

If nothing else, at least spend some time learning about brake ratios before moving forward.  It's very simple math, and if followed, it will greatly improve brake feel and function.

[longshanks]

i have pics of the MC in the previous thread i linked at the top

[FunJimmy]

It would appear that longshanks just wants someone to tell him that his current master cylinder will be OK, and it will.