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mechanical brake springs seem off??

2K views 20 replies 7 participants last post by  jessee 
#1 ·
hey pre 57 rear panhead/knucklehead brake. I'm putting it together and my springs arn't returning/ holding together like i think they should? am i missing something before i install it??
 

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#2 ·
Let me guess, you got the shoes from v-twin right? If you still have the oem shoes you'll see the spring holes are in a different position. If you have to run those go to an auto supply store and look through their brake springs. Or try a good hardware/ farm store. Whatever ya do make sure the springs don't rub on something once your done , like the drum.
 
#3 ·
Once you get it all done, leave the top nut loose where the shoes pivot and step on the pedal and hold it. Then tighten that top nut up. That will center the shoes in the drum.Adjust the clevis so you don't have too much pedal travel but don't get so tight the shoes drag.
 
#6 ·
Welcome to the world of shit aftermarket parts.
If the springs are not under tension when installed they are not right. That is simple logic and despite the aftermarket crap should be obvious. So back up a bit and think about it. And have faith in yourself, not some lame ass parts manufacturer who just wants your dollars and cares less after that. Using shitty parts is adding to the confusion. Think about how brakes work, and why running clearance is needed between shoes and a drum.
And when you do get springs that work, mount them from underneath. That way they don't try to cock the shoes or contact the backing plate.
 
#7 ·
If you have the oem shoes you or me or someone on here can easily reline them. I get brake lining from McMaster Carr and drill and counterbore it to fit. Rivet 'em on and you're good for about another 10 years. The aftermarket was designed to line the pockets of people who don't know or give a fuck about you or that scooter.
 
#8 · (Edited)
My $.02, you only need bottom spring on 36-57 rear big twin brakes. Aftermarket quality issues aside, unless that spring is so loose that there's slack in it, it should pull the shoes closed.

That said the spring doesn't LOOK that loose, so the question to me is, on what are the shoes hanging up? Asumming all parts are correct and installed properly, they LOOK to be hanging open on something. Is something jenky on the top pivot and cups? Are they hitting the backing plate (bent, shoes installed correctly...)? Are they catching on the lower cam (too much shimming, bushing not seated in backing plate....)?
 
#9 ·
The spring next to the brake cam, looks loose. When it is in there correctly, it should have some slight spacing between the coils. When fully tight against the cam. So, a different spring is needed, or redrill the holes further apart. If the spring is easy to put on, it is not the right length. If you have to fight it like a wildcat, it is probably short enough. Correctly installed, you should not even be able to pull the shoes off the cam, without a pry bar.
 
#11 ·
jessee,
It's entirely possible that even though you ordered the correct parts (springs, in this case), and received parts in a package that is labeled correctly, they could be the wrong parts! There are a number of different Harley brake springs, and you may not have the correct ones.
I just measured up a rear brake spring I have, and in the relaxed state it measured 3.43" inside the hooks. I also measured up a set of re-pop shoes mounted with a good brake cam and pivot pin and the distance between the spring holes is 3.67" (measured at the closest point between them where the springs make contact, NOT center-to-center).

Specs for the Big Twin lower brake spring 41835-30 (the one at the brake cam side, which as far as I know is the only spring the factory used on the rear brake from '38-'57)

relaxed body coil length (not including hooks) 2-1/4"
overall relaxed full length (including hooks) 3-5/8"
coil diameter 9/16"
wire diameter .155"

When assembled correctly, everything should move free and easy, the only resistance to movement should be the tension of the spring. Hope this helps you out :).

Geo.
 
#12 ·
so i used a spring lying around my shop, i think from my iron head kickstand or something.... anyway its now tighter than a nuns count! which is a good thing!

so again shitty aftermarket taiwanese bullshit parts... so i go to install in my drum, and now they won't go in , the pads are too big, I'm going to sand them down tomorrow and get them to fit. i think moral of the story is buy usa made stuff
 

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#16 ·
thanks old wrench for all the specs this will be help ful. but if I remember correctly on my ironhead stock shoes and springs I remember not being able to really pull the shoes apart with the springs in. so that being said they were under alot of tension. as they sit right now i dont think they are too tight. def tight tho. I think they are def good enough to run.
 
#19 ·
Yes, DO sand the pads. Lay apiece of sandpaper in the drum and work the pad into it to match the radius of the drum. A technique referred to as arcing the shoes (plenty on the net about arcing brake shoes). It is the only way to get full contact, and useful brakes. And bevel the ends of the pads, a long slow bevel so they don't chatter upon application.
 
#20 ·
So I sanded my pads down enough so there's some free play in the drum and the spin freely. But when I put the backing plate on the backing plate binds up a lot in the drum and when I dissemble it it's extremely hard to get out of the drum. Has any one experienced this before?? What did u do??
 
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