The Hodaka Club Forum

You may have already covered this but I guess you're not planning on kick starting with the rear set in the way? Maybe one of those roller starters or just bump starting?
An easy solution for the rear brake would be to use the cable set-up and run up to an extra lever on the clutch side. Could be a shorty type lever below the clutch lever. Most of your stopping power will be from the front brake anyway.
Mike

Are we shying away from a cable or did i miss something? -----Clarence

Bullfrog wrote: Your last post suggests that you are thinking about linkage from the brake lever actuation arm forward to near the swing arm pivot and then linkage from there back to the hub brake lever? Or did I misunderstand the paragraph? Seems like a lot of linkages - but if the various pivots and Heim joints are pretty "tight" (not much free play), then it may be as good as (or better than) a cable setup.

Ed

Hey Ed. These ideas are are certainly flexible. A shaft and crank near the pivot point of the swing arm would only be a change of direction for the brake rod and only one step away from a direct connection. I'll try to fake it with a mock-up for our satisfaction. I kinda have to see things. The cable idea is still on the table as I've got a front brake plate mounted on the rear which is a start.

Maxie

MWL wrote:You may have already covered this but I guess you're not planning on kick starting with the rear set in the way? Maybe one of those roller starters or just bump starting?

Mike

Hey Mike, Thanks for your comments. We haven't discussed the starting system at length yet. The kick start shaft, lever and gear will be non-present, I guess is the word. I haven't weighed the components but these parts probably represent nearly 1% of the total weight of the vehicle. Removing the starter gear from the crankcase adds a small but significant power gain from not having to spin the partially submerged gear in the transmission lubricant.

I'm getting too old for bump starts and envision a stand/starter mount to start the engine with some battery powered device which would be easier on the old guy.

Maxie

Hey Bill, thanks for the tip on RC components, I'll explore that today!

Maxie

Hey Ed and all. Here's a really quick and dirty mock-up of the pivot point I envision. I probably could have incorporated the original tube shaft if the DPO hadn't cut off the bracket. Pretty clunky looking now but could be precision made.

I'm still trying to envision the cable hook up which is still a possibility but the vision has not come to me yet.

Maxie

It may be photo perspective . . . but is there any reason to be concerned about the toe end of the lever swinging down and contacting the actuating rod?

Yeah, while a cable seems easy on first thought, creating the "anchor" spots for the cable housing ends won't be easy. And there is the worry about rear brake cables which aren't nearly stout enough to do the job without housing "compression"/deformation.

Ed

All clear here Ed. Now that I take a closer look, the Heim joint probably could be on the inside of the brake arm giving even more clearance.

Maxie

Kewell!

. . . and it occurs to me that my concern about a truly stout rear brake cable housings is coming mostly from a dirt biker perspective . . . prolly not a big deal for speed record type of bike.

Ed

To really be serious on the record attempt theme some other serious mods will have to be made. Don't forget the dual purpose road racer identity with its large heavy front brake and some corner turning tires which it will have first. The general design should lend itself to both purposes. Top speed can extensively tested in the road racer guise and should one want to try some record attempts other wheels could be fitted. Skinny aluminum rims and tires would be needed for less weight and rolling resistance along with less frontal area. Real gains would be noticed along with a reduction in billfold thickness. Just putting things in perspective as the project moves slowly along. Meanwhile one of the main objectives of entertaining me is being met as this is a really fun project without deadlines. Having it in the shop also gives me a feeling of well being at least in the motorcycle department. Just philosophizing here.

Maxie

"A reduction in billfold thickness"

He he.

I see that I'm getting ready to be put on page two which means I haven't been reporting lately. Things are still slowly happening and distractions are still present. It appears that the best solution to the rear brake hook up will be with a one pivot linkage rather than a cable. This was all mocked up using a damaged front wheel brake plate with a cable end hold. It fits fine with the bearing collar cut down. A sealed bearing will be used as there is not room for the stock seal. I'm out of rear brake plates and have a useable front by cutting down the collar once again. This will also leave the option of a cable later.

Check out the brake cam lever after removal. I've never had one be so tough. It appears that it was pressed on at the factory in the right position and was to be a permanent fixture. I didn't have any pullers that small but did get a chain breaker in there which only bent the lever. Hmmm, I have more levers, let's get this thing off by sawing through the slots around the shaft where the bolt goes through. A fight to the end.

Also the tires have finally arrived for the road race version. I'm still cleaning and shining the rims which is no small matter. I'm quite mobile after the knee operation but not quite ready for wrestling tires on the garage floor. My cruel motorcycle friends call me the one-legged arse kicker. Maybe I'll make them help.

Well, that's the story for now, just checking in!

Maxie

I was searching the Hodaka shed a few minutes ago for miscellaneous project parts and run across most of a kick starter assembly. Just for fun and my own curiosity I threw them on the scales. Hmm, more than I thought at 2 1/2 pounds. That along with the gear running in oil all adds up to additional mass and negative forces in our equation F=ma. Probably worth the effort except for an easy start.

Maxie

Well you're probably tired of Max's engineering on the linkage path to the rear brake. Many paths have been explored each with their problems or at least challenges. Hey, solving problems along with entertainment is one of the main themes of this project and with no deadlines I can mess with it all I want.

On the non-cable approach a shaft is needed for the pivot arms. One quick way would be to install a 3/8" diameter bolt into the existing brake shaft hole in the frame (or drill a new one). 1/2" tubing fits nicely over the and the two arms could be welded directly to the tube as shown in the mock-up. Not hi-tech but probably sufficient to fulfill the mission to pull the rear brake.

An improvement could be made by replacing the grease filled bushing with ball bearings. Check out these cool little 1/4" shaft bearings that arrived yesterday to solve the problem. The arms can then can be welded or bolted to the nearly friction free shaft.

OK, that's the plan for now---Reporting,

Maxie

Ah, I think this is going to work. The levers are just mock-ups. It looks like welding the levers on will work. Once the levers are welded in place and the shaft cut to length it will just be a matter of sliding the shaft through the two bearings and securing the Allen screws in the bearings. Since all forces are pulls, I ordered 1/4" Aluminum rods for linkage and new rear brake rod. I never pass up the chance to save a few grams. And yes, that foot peg plate has to go. More than a few ounces there!

Max

Hmm, the more I look at this I think the inner lever should be adjustable on the shaft while the outer one can be permanently welded. I've already done quite a search for a bolt on to no avail. I'm off to Ace Hardware and/or the local farm store as we speak to find a collar to build my lever around this example.

I'm sure you have probably noticed by now that I prototype a lot to say the least. I'm always amazed by people who can look at an engineering problem and come up with a total solution in their head and proceed to build a solution. Not me. I've got to see and proceed which also works but can be time consuming. More than one way to skin a cat but you wouldn't want me to be designing a product for you and being paid by the hour, LOL. So much for my spacial relationship deficiency but this project is really good for my problem. I highly recommend it! Slow but sure but really fun! I must also say that everyone's input is appreciated!

Maxie

very cool high tech brake pedal and linkage

Rich

Maxie,

I REALLY like watching your prototyping efforts! I too have found that many "errors" can be avoided by prototyping in cardboard and wood dowel (etc) before putting major time into metal working.

It is probably my inability to relate well to bikes meant for hard surfaces . . . but will a 1/4" brake pivot rod be a bit of a "flexi-flyer" torsion rod actuating system?

Ed

Bullfrog wrote:It is probably my inability to relate well to bikes meant for hard surfaces . . . but will a 1/4" brake pivot rod be a bit of a "flexi-flyer" torsion rod actuating system?

Ed

Yes and no. Quarter inch is pretty light for a torsional load. On the other hand, the reach between levers is short, which will mitigate the issue. A full panic stomp will probably twist the rod permanently. I would also have an issue with the idea that one of the levers will be intentionally adjustable. During prototyping, that's fine. Once locations become certain, I would fully weld both levers AND I would seriously consider slipping a tight fitting stiffening tube over the rod, and welding that, just between the two levers, to help transmit torsional loads. The free length that goes through the bearings is okay for now unless it becomes clear that the rod will also bend too easily at the first bearing. If the rod bears on the frame tube midpoint between the two levers as it appears to do, it will probably be okay, but is something to watch for. Otherwise, either heavier construction or a pillow block at the frame to make the brakes dependable during less than optimal situations.

Hey thanks all! The 1/4" shaft is under scrutiny but really seems really solid. The rod only protrudes past the bearing less than two inches and appears to be adequate. Jack, I like and agree your idea of a stiffening tube to strengthen things up things up between the levers. After looking at the idea of that little allen screw actually holding the lever on the shaft seems somewhat iffy. Probably welding is the way to go as you say. All to be tested for sure. My mind changes every few minutes and everyone's input is appreciated. I do have an open mind. Your voices have been heard and will certainly be considered come dawn.

Meanwhile I built an aluminum rear brake rod from 1/4" stock which is slightly larger diameter than the stock steel one. The brake adjusting nut was drilled and re-tapped as was the rod was threaded to 1/4-20. The die did fight me a bit (quite a bit actually) and kept clogging on the aluminum. The heim fitting for the other end requires a 1/4-28 and I hope it goes a little smoother than the other end. The steel 1/4' rod threads really nice but the weight difference of 3-4 feet is noticeable. We'll see.

Maxie

Oil the die and rod.

Enjoying your "TLAR" engineering sessions, continue on.
I think the torsional strength will not be a problem. This is a rear brake and you'll reach the limit where the wheel locks. It might even help the "feel" of the brake to have a bit of torsional springiness.

Bill,

Here is where I will disagree completely. Torsional springiness is the verbal equivalent of spongy brakes. This is a safety issue as well as a functionality issue. Brakes should have a nearly linear response to pressure, otherwise, you will never know what your brakes will do until you wait for a reaction from the bike. At 80mph this is not acceptable. It gets worse as speed builds. You can't hit the rear brake and wait for the rear tire to break free to know how much force you are applying, and frankly, my attention at speed will be focused somewhere else than filtering feedback from a spongy brake rod.

Brakes and steering are critical components of a safe motorcycle. Compromise for the sake of weight isn't a wise approach. For an example, look no farther than the front brake hub assembly to be used here. If that's lighter than an Ace 90 front hub I'm the Pope. So the real question is whether the brake assembly is reliable. It is possible that a quarter inch rod will be enough, but if it has any wrap to it under pressure, all that will create is a lack of feel and a tendency to shudder. Having the back end bunny hopping because of a springy brake rod would be entertaining, but not really something to aim for.

Look at the brake assemblies used by Hodaka on its various models. You won't find a torsionally resilient rod anywhere in any of these parts. Using a quarter inch pivot rod through the bearings may well work if the foot end of the assembly is well supported because the bearing end of the assembly doesn't carry a load and isn't being twisted. But for the parts that matter, it would be better if the two levers stood off on a half inch welded tube rather than a quarter inch rod. These parts may feel stiff now, but I ask if that feeling arises from the hands or the feet. The Ace series used a hefty welded tube between levers, and generally, the foot lever would bend well before any other part of the system failed. The footpeg setback here should also be strong enough that it is not the functional link between levers that fails first.

When Max is in the finished up mode and into his test cycle, if it feels really really good and functions really well only functional parts will satisfy. Anything less will be modified. Hodaka was created by the folks thinking outside the box. If it does not function to desired standard, seek the wisdom of Jack the researcher, talent minded with comprehension. -----------Clarence

Because we are sharing thoughts here and I would normally be accused of overbuilding. The 1/4 shaft seems light too me.. Also the bearing on the other side of the frame is adding little support. A bearing fastened to the frame would help support the shaft and balance the thrust. ------------Clarence