Topic: suzuki 4LS brake on their 750 ? edited - photo w/ questions - Need factory spec

[greenjeans]

Here's a photo of the 2 axles:



The top is the Suzuki axle.    Both are 15mm diameter.    What I'm having trouble finding is the distance that the factory specified as the distance between the fork legs.   I'd assume that it would be a nice round number like 150mm or 155mm, but you know where that gets you...

Just looking at them side by side, they look to be within 1-2 mm of being the same (between the fork distance)

Looking at the axles you can see where my problem lies.

The Suzuki axle ends are 22mm so they won't fit in the bottom of the Honda fork legs.  
The Honda axle has the "nut" portion of the tightener (for lack of a better term) toward the inside of the assembly.  The nut and small lip on the outer portion keep it from moving left or right.  If the "nut" portion of the tightener was removed, it would fit.  But... then how would it be tightened ?

If I chucked the Suzuki axle in the lathe and turned down the adjusting nut and other end of the axle so it would be 20mm would it weaken the adjusting nut too much to be safe ?

My questions seem rambling at best, but I'm hoping one of you guys know what I'm trying to ask and can figure out a brilliant solution.

Any suggestions greatly appreciated.

[greenjeans]

Nobody ?

[johnrdupree]

From what I understand the vintage race crowd loves those brakes.  Posting the question in the racing section may get you more hits.

Good luck, and post pics when you get it done.

~john

[jaguar]

i would think that you would get better performance from the stock set up

and yes the vintage racers love this brake and pay big bucks for them

[754]

 To find width between forks, just measure yours.. keep in mind one side is relieved for speedo drive, so 1/2 of width is not the middle, it is less than that

 The Suzi legs wont help you if the triple trees are wider on the Suzi. If the Suzi legs are 4 bolt on the bottom, that is a plus. What did Suzi use for a speedo drive?

 I would not go )anchor) off the fender mounts, there is a much bigger brake lug on each forkleg..

[greenjeans]

To find width between forks, just measure yours.. keep in mind one side is relieved for speedo drive, so 1/2 of width is not the middle, it is less than that

 The Suzi legs wont help you if the triple trees are wider on the Suzi. If the Suzi legs are 4 bolt on the bottom, that is a plus. What did Suzi use for a speedo drive?

 I would not go )anchor) off the fender mounts, there is a much bigger brake lug on each forkleg..

I figured I could measure mine, but I was hoping that I could get a definitive measurement so things are accurate.  I'll measure mine and just see how close to a round
number I get...     It would likely be a round number like 150mm  vs  152 or something - make sense ?

Forgot all about the brake lug on the forks - thanks

As for performance, I've just wanted one of these monstrosities for a while.   It will be plenty of brake.   It's just going to be for street use anyway.

[greenjeans]

edited.

[johnrdupree]

I would think keeping the Honda axle and adapting the Suzuki hub to it might be your best bet.  The axle nut is important because it is what locates the front wheel in relation to the rest of the bike.  The nut is positively located on the bottom of the fork by the shoulder and hex section, a spacer spacer is against that, and the wheel bearing is against the spacer.  This combo puts the center of the wheel a specific distance from that fork leg.

The trick here is to get the center of the Suzuki wheel in the same location.  I assume you already have the 4LS hub.  Can you slide the Honda axle through the hub, with no spacers, and tighten the axle nut?  If so, a custom spacer on the axle nut side can be made up.  Are you going to retain the speedo drive?  (Are they even compatible?)  If you're not going to use the speedo drive, another custom spacer will fill the remaining space.

The important measurement here is the bearing/spacer stack that is clamped between the ends of the axle.  What I think you need to measure, on both hubs, is the left hand spacer, left bearing, and the center spacer.  From that you can figure out the distance from the inner axle nut face to the center of the hub (assuming the hub is symmetrical).  For example, on my 550 (which I just went out and measured, the wheel is conveniently broken down for new bearings) the numbers are:

left spacer = 17 mm
left bearing = 13 mm
center spacer = 75 mm

This puts center of the hub 17 + 13 + (75/2) = 67.5 mm from the axle nut.
(If the wheel isn't broken down then you just measure the hub at the bearings.  On the 550 it would be 13 + 75 + 13 = 101.  17 + (101/2) = 67.5 mm.)

Pretend the Suzuki hub is 110 mm, then the spacer you need is, in this example, would be 67.5 - (110/2) = 12.5 mm.  This puts the wheel where it needs to be and you just have to measure for a spacer on the other side.

I wrote all this in a stream of consciousness so take it with a grain of salt.  If the Suzuki hub is too wide for the Honda axle, then I don't know what to do.

Good luck,
~john

[greenjeans]

Thanks, John,  A few things about the Suzuki hub.  It is approximately 6-9mm wider than the Honda hub.  The speedometer drive is within the brake plates/hub.  Haven't checked too closely on the cable ends.  I doubt I'll be lucky enough to get a suzuki speedometer cable to thread into the back of the Honda speedometer.

The Suzi hub would actually fit between the fork legs IF the "nut/hex" portion of the adjusting nut wasn't there.   If Honda and Suzuki just used the same thread pitch/size, it would be an easier fix.

As of now, i think I need to machine the width of the "hex" portion (6mm) from 1 side of 1 of the brake plates.  Then I will be within 1-2 millimeters.  

I'd like to know the actual number spec'd by Honda & Suzuki of their hub widths (completely assembled).  I'd like to get things spot-on.

I'd guess that if the Suzi hub is, at that point, 1-2 mm too wide  (it would still fit between the fork legs) but would cause some degree of stiction with the forks.

So.. my tenative plan is to machine 6-7mm off one of the brake plates where the arrow is pointing, and 1-2mm off the other.  I'll use the Honda axle and the nut will make up the other 6mm, centering the assemly between the forks.

I still have yet to find the actual factory spec'd measurements of either hub.    Anyone ??

I can't really machine anything until I have the "gospel" of those measurements.

Here's where I think I will have to machine material off the brake plates.:

[greenjeans]

To find width between forks, just measure yours.. keep in mind one side is relieved for speedo drive, so 1/2 of width is not the middle, it is less than that

 The Suzi legs wont help you if the triple trees are wider on the Suzi. If the Suzi legs are 4 bolt on the bottom, that is a plus. What did Suzi use for a speedo drive?

 I would not go )anchor) off the fender mounts, there is a much bigger brake lug on each forkleg..

Looking at my forks, they appear to be symetrical/mirrored.  I think that the nut/hex portion of the adjusting nut gives the offset that the speedometer uses.  I could be wrong - I'm going back out to the shop, so I'll take a closer look and post another photo if it helps.

[greenjeans]

Don't know if you guys are interested or not, but I asked the same question over at caferacer.net and it became pretty entertaining.  Things have calmed down a bit now.  Here's a link if interested:  http://caferacer.net/forum.html

Still have yet to find published widths of either hub.