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Disk Brake Conversion on Wishbone Frame

12K views 54 replies 15 participants last post by  joe49 
#1 ·
Hello, been a while since I posted here. Yesterday was the second time I broke the linkage on my mechanical rear. Both times I was lucky enough to not be in any traffic, both times were minutes after splitting lanes and going freeway speeds, so I think I may have pushed my luck enough. Besides that, there has always been a death rattle that shakes my whole bike when I hit the mechanical brake, so maybe I should just go ahead and put something reliable on.

Looking to build a dual flange and put a nice disk on it. I am curious what people are doing with their master cylinder mounts on a stock rigid frame. Also what are my options for American made master cylinders? Calipers too, if someone has any strong opinions. Thanks in advance.

Also, I'm still running a dual action front drum, but it still barely holds me on a hill, so anyone have a link on a detailed setup procedure that may include anything I may have missed?
 
#2 ·
My panhead has a 70's ish fl rear wheel with a gmb caliper and a homemade bracket.the master bolts to the lug on the front of the frame that the brake pedal bracket bolts to.iirc,the brake pedal is also 70's vintage.the first master I had on the bike was the wagner-lockheed style then I changed to a 70's fx style iirc again.

Sent from my LM-X420 using Tapatalk
 
#5 ·
Havent seen a nice way to anchor them without welding on the frame that allows the stud enough free room for chain adjustment. Also would potentially need to widen the axle space from what I have heard, though I suspect this had already been done on mine.
 
#10 ·
Hello, been a while since I posted here. Yesterday was the second time I broke the linkage on my mechanical rear. Both times I was lucky enough to not be in any traffic, both times were minutes after splitting lanes and going freeway speeds, so I think I may have pushed my luck enough. Besides that, there has always been a death rattle that shakes my whole bike when I hit the mechanical brake, so maybe I should just go ahead and put something reliable on.

Looking to build a dual flange and put a nice disk on it. I am curious what people are doing with their master cylinder mounts on a stock rigid frame. Also what are my options for American made master cylinders? Calipers too, if someone has any strong opinions. Thanks in advance.

Also, I'm still running a dual action front drum, but it still barely holds me on a hill, so anyone have a link on a detailed setup procedure that may include anything I may have missed?
Hey bud,

If your bike is 'death rattling' and snapping linkages like that, there must be something that's not spaced properly, or the spacer you're using is wrong for the mech drum. I've never had a linkage go, let alone any bad rattles from my drum.

I appreciate you may want to change, but may be worth investigating why it's doing that rattle, sounds like something out of true, spaced badly or just not right.
 
#13 ·
Could be. I was always curious about this gap. It squeezes in the axle plates when I tighten it down and there is no play, but still thought it was odd. The axle isnt long enough to secure if I had a spacer filling it. Same old man that told me that I would need to widen the axles told me that if I measured mine I would probably find someone had already done it at some point but again, idk. He is a very knowledgeable man running a shop for 50+ years, but he was very antiquated with his ideas.

This is the first time I broke a rod, the first time I sheared a cotter pin. I use key ring loops now. Another mentor always said mechanical brakes put too much trust in a bobby pin and shit if I didnt prove him right.
 

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#17 ·
Maybe I am wrong and should be shot for it, but a quick reread doesn't show me that your mention of the (characteristicall, I guess?) horrible front brake went anywhere in terms of attracting advice. Here I am to save the day.

You probly don't need me to tell you that on a bike with two functional brakes, the front handles, like, 85% of the stopping. A good back brake is only as effective as traction allows. You can lock up your hind wheel easy, but then it'll just skate along helplessly. (I'm overstating this, but not by much.) Rear-to-front redistribution of the bike's weight takes place when it slows down abruptly, by whatever means (engine braking, back brake, t-boning a school bus). If you're using a front brake, that weight transfer is good; using the back brake, it makes matters worse.

If your bike was mine, which, I should be so lucky, I'd fix the rear brake enough so it doesn't break when used; but I'd put my effort and money into a real good, or even a pretty good, front disc.

I know a disc is an anachronism on a Pan, and yeah there are aesthetic arguments for running a spool front or an incompetent period-correct front brake, but you're already talking about running a disc, so why not put it where it'll help you the most?

End of sermon.
 
#18 ·
Hear all of this, but a disk up front is the most detrimental to a classic look imo. It would also add a large unsightly reservoir to my handlebars that I would have to stare at all ride every ride. I have however, considered the Cannonball springer drums that are hydraulic. But I couldnt get myself past the control. A disk on the rear, while not aesthetically ideal, is still more forgivable.
 
#20 ·
I made one of the Wargasser style juice brake stays for my build out of 6mm 316 SS, as has been mentioned it uses a vertical slot that allows chain tension adjustment. Mine works perfectly.

I'm hesitant to give out dimensions as ultimately i copied the Wargaser style and don't want to go about trying to damage someone business by giving out instructions on copying product, but what i can do is sent you an extra one i made that is ready to go.

If you decide to go this route let me know and i can send it your way for postage only, might be $15 US, i'm in New Zealand so has a ways to travel.
 
#21 ·
That's a kindly offer. You guys knock me out.

Fredo, I momentarily forget where I saw it, but I've seen a nice-looking old (springer era) stock H-D brake that was converted to twin leading shoe. Given that the stock drum size is only, what, 7"?, and given that a big twin weighs, what, 4 tons?, I wouldn't expect it to ever be a great brake. But a TLS conversion might make a real big improvement, along with looking cool as hell to people who understand what they're looking at. Would something like that appeal to you?

I agree that a big ol' disc and a stockish springer combine to make a pretty homely spectacle. And come to think of it, don't many of you knowledgeable guys have doubts about whether the springer is stout enough to cope with a lot of front brake? ... I think I ought to shut up now.
 
#29 ·
Wonder if you could hide a cable controlled master to run the juiced up front drum??
...or same for a later rear juice drum, using the cross shaft etc.?
Just some thoughts I've had considering my repop knuckle project (maybe!)...haha.
yep, fab kevin used to make a kit like that years ago.
disc brake, master hidden under the tank, pretty simple setup, can be done using a sports bike rear master.

https://www.fabkevin.com/shop/parts/brakes/remote-master-cylinder/
 
#26 ·
Fredo, do you have any interest in making that mechanical rear work correctly? 'Cause to me, that's the easiest and cheapest.

And they work fine if they're not all fucked up.
 
#31 ·
You know what works real fuckin' good on a Harley chopper?

A drum brake.

If the olds won't be the hard-line traditionalists, then I'll step up and take that on these broad shoulders. Fredo, let's make your drum work right.
 
#35 ·
I have the dual cam front brake drum on the springer from Cannonball. It barely holds me on a hill, bought it brand new. I'm not opposed to keeping the rear mechanical if it would be more reliable and not rattle the entire bike louder than my exhaust. I have already replaced the pads and had the drum turned at a racing brake shop in Costa Mesa. Paughco backing plate (my second one, both rattled) and I dont remember if it is a Paughco drum too. I have had the thought of bringing the bike to someone and just paying them to setup the brakes just to have a baseline and see if they noticed anything I didnt that is causing these to suck so much. But if anyone has any tips for what to look for, the bike is on the lift and I am all ears.

Paughco is out of the clevis at the end of the rod, and they dont know when they will do a run. My brake rod broke off inside of mine, and I will try to extract it but I'm not very good at welding yet, so idk if I can make the old trick work where I weld a nut ont the snapped off stud to extract. I dont want any V-Twin if I can avoid it, so I may run a grade 80 chain from the crossover shaft to the actuator lever on the backing plate for the time being, which would circumvent the clevis. Any strong objections to this?
 
#36 · (Edited)
Fredo, just because it is Paughco doesn't mean it's perfect. I have a brand new brake rod and clevis I will give you for free. Just don't ask where it was made. It's W&W but....
Regarding your backing plate. If the plate is loose you are missing spacers. It should be held inplace tight by the axle. If the swedged in adjuster are loose you have to throw it away The cam cannot rattle as there are two springs forcing it to sit in its bushing. The whole setup needs up close inspection by an expert.
I just thought are you running mids with the linkage in a push instead of pull environment?
It wasn't designed for that.

Please pm me your address so that I can mail out the rod and clevis
 
#37 ·
Really good of you Mike,

I run mine push as a have a Di jong pedal, but I had to upgrade to 1/2 inch stainless to make it work! lots of machine work and a lesson off the old man in threading a bar!

Fredo, as Mike has said you're missing a spacer. My Backing plate is SNUG SNUG. There shouldn't be any movement at all. When they're set right, there shouldn't be anything under huge tension. When you get new bits do yourself a favour, drill out the hole don't use a clevis and put a bolt and nylock nut on it. I have it on mine, works a treat.
 
#41 ·
I find the last shop dope paragraph about brake relining and adjusting very interesting. Loosen the pivot and applying full pressure? I never thought of that.
Thank you Eric. Great contribution as always.
 
#43 ·
Hey guys, yeah, the axles are supposed to be the same, but I also prefer the way the big blocky early one looks.

Mike, hugely grateful for the offer but I already had a buddy order one of the rods for me. Im going to try to salvage the clevis, but if I run into an issue, I will let you know! Really appreciate the offer and advise, always.

That shop dope is very interesting. I went out and looked at the brake for the first time since unloading it from my truck. I have a bunch of play front to back in the cam shaft. I looked it up in the part in the parts catalog, 4055-31. I expected a washer, maybe being told to shim to fit, but the part specifies a spring washer. What I assume is the issue without opening it, is that the person I bought the brake from used a washer, and since I didnt know any different, may have perpetuated my issue when I swapped components between backing plates. No spring will allow the slop and that probably translates to the chatter. That would make sense why the rod broke, it was probably whipping around while I braked. I will see if I can get my hands on one of the spring washers, may even rebuild some oem brake shoes I have kicking around to replace the aftermarket ones in there. If after that it still rattles, then I will just have to throw out the whole bike. Ha!
 
#44 ·
Hey guys, yeah, the axles are supposed to be the same, but I also prefer the way the big blocky early one looks.

Mike, hugely grateful for the offer but I already had a buddy order one of the rods for me. Im going to try to salvage the clevis, but if I run into an issue, I will let you know! Really appreciate the offer and advise, always.

That shop dope is very interesting. I went out and looked at the brake for the first time since unloading it from my truck. I have a bunch of play front to back in the cam shaft. I looked it up in the part in the parts catalog, 4055-31. I expected a washer, maybe being told to shim to fit, but the part specifies a spring washer. What I assume is the issue without opening it, is that the person I bought the brake from used a washer, and since I didnt know any different, may have perpetuated my issue when I swapped components between backing plates. No spring will allow the slop and that probably translates to the chatter. That would make sense why the rod broke, it was probably whipping around while I braked. I will see if I can get my hands on one of the spring washers, may even rebuild some oem brake shoes I have kicking around to replace the aftermarket ones in there. If after that it still rattles, then I will just have to throw out the whole bike. Ha!
Can you throw it across an ocean?
 
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