Author Topic: Hub identification for brake shoes and sprocket  (Read 800 times)

Offline adunham1

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Hi everyone,

In what I hope will be the last big expense before getting my 61' SR back on the road, I need brakes front and rear, a rear sprocket, and tires.

I am trying to identify what hub I have to purchase the correct items, but I can't seem to quite figure it out. I'm sure this has been asked a million times, so apologies in advance.

Let's start with the rear hub. Full width, marked with the number "DA17224" and what I *think* is 42-6616, although I can't find any information on that number. 8.5" in diameter, so I assume this is the 8" brake.

The front is half width, with no visible markings on the areas I can see. Again, 8.5" diameter so assumed 8" brake.

Here are some photos of each to help.

Thanks for any help!

Offline Billybream

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Re: Hub identification for brake shoes and sprocket
« Reply #1 on: 21.04. 2020 04:15 »
You should have cast iron full width hubs front  8" and rear 7"
1960 Super Rocket, owned since 1966, back on the road 2012 after being laid up for 29yrs.

Online morris

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Re: Hub identification for brake shoes and sprocket
« Reply #2 on: 21.04. 2020 09:16 »
Where did you measure them?
If measured on the outside they both are about 8 1/2, but they should be measured on the inside. I think you'll find 7 inch on the rear and 8 inch on the front
The rear full width brake with the lever pointing downwards is correct for your model year, but the front should normally have the full width also, although I'm not sure if that's the case for an SR. Maybe others can confirm or deny.
Don't be tempted to change it though, unless you're looking for absolute originality. The half width front is far superior and going to full width will also involve changing the forks.
The 7 inch rear FWH can be made into a good brake with the right linings and a careful setup of the lever angle. Don't use "modern" bonded shoes, they are way to hard to be effective.
A good address for brake shoes and linings is Gary Parkin; http://www.gp-motos.com/
The rear sprocket is easy to find. Most dealers stock them.
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Online JulianS

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Re: Hub identification for brake shoes and sprocket
« Reply #3 on: 21.04. 2020 09:28 »
The front brake fitted could be Gold Star type - which had shoes 1 3/8 inch wide, or it could be A65 1966 type which looked the same but had a wider braking surface and shoes 1 5/8 inch wide. You will need to measure the width of the shoes to determine which one.

I agree it is a much better brake than the original full width.

Offline Swarfcut

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Re: Hub identification for brake shoes and sprocket
« Reply #4 on: 21.04. 2020 09:34 »
   Morris says it all. That 8" front brake is a good all rounder, far better and easier to set up  than the full width type. Its the latest variant you have there, with the finned drum, carried over to the A65 and Gold Star, with the caveat outlined by Julian regarding the shoes.

  The rear is set up with a reversed lever (pointing down), as on late models. Altering the lever angles to get maximum leverage and least free play by experiment can be a bit fiddly, but with a good non stretched outer cable and full shoe contact it can be set up to work very well.

 Swarfy.

Offline adunham1

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Re: Hub identification for brake shoes and sprocket
« Reply #5 on: 21.04. 2020 16:40 »
Thanks guys! I know it sounds silly, but with all the information out on the internet, it eases the mind a bit when you get a response from more than one "resident legends." Ha. I suppose one could become one by spouting nonsense on 100 posts a day, but I'd like to believe that isn't true.

Yes, Morris I did measure on the outside. After some more digging and the responses here, I'm sure you're correct with the 7 rear and 8 front. The bike isn't a perfect replica (nor do I want it to be) so a better working brake is perfectly acceptable by me. I've already spent way too much money for what I've got sitting around right now. I think I may have been bamboozled early when I purchased it. Thank you for the contact for Gary. I'm going to disassemble the rear today and see what I find.

I wish I had measured the front brakes when I had the front end apart for front suspension work. Now it's a bit more of a job.

Speaking of the lever angle, I worked on a four leading shoe brake from a mid 70's Moto Guzzi Loopframe and they were very particular about a 90 degree angle on the levers. Does that apply here or is more of a trial and error thing?

Offline Swarfcut

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Re: Hub identification for brake shoes and sprocket
« Reply #6 on: 22.04. 2020 08:44 »
 With the brake applied, the angle between the lever and the cable should approach the magic 90 degrees.  This is because before reaching 90 the applied force exerts increasing leverage. Once the lever passes over 90, less rotational force is applied to the cam as the applied force is in effect trying to stretch the lever rather than turn the cam. The cable end of the lever is moving in a circular arc and maximum leverage is at 90. Moving away from 90 to an obtuse angle reduces the applied force. Not too well expressed there, but that's the crude explanation.  Hard braking set before 90 degrees means there is a little in reserve for the OMG moment.

 The cross shaft lever can also be adjusted on the splines to give the same pre 90 angle with the cable, but this time set at an obtuse angle with the cable as set in this way the smallest rotational movement gives the greatest pull on the cable. With the brake lever pressed, as the angle between cable and lever moves towards 90, more of the braking effort is directed to pulling the cable.

 Brake performance, adjustment and tricks to improve the set up have all been debated on the Forum, just a matter of searching through it.

 Swarfy.

Online morris

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Re: Hub identification for brake shoes and sprocket
« Reply #7 on: 22.04. 2020 09:07 »
This is the angle to more or less look for.
Picture is with the brake not applied. Ideally the lever would be a couple of degrees more backward to have a perfect 90° angle with the brake applied but this setup works for me. Wheel locks without too much effort.
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Offline Swarfcut

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Re: Hub identification for brake shoes and sprocket
« Reply #8 on: 22.04. 2020 19:08 »
    Morris.... That's not the 90 degrees I'm talking about. Your lever has passed through 90 degrees, (cable/ lever) and as such is no longer capable of exerting maximum braking force. Sorry to differ, but I'd have the lever set  to point more to the rear, with a bit in reserve.

 Adunham...Have a look at internet images of your rear brake. The majority are set up correctly, pointing down and slightly to the rear.

 Swarfy.

Offline adunham1

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Re: Hub identification for brake shoes and sprocket
« Reply #9 on: 22.04. 2020 21:50 »
Thanks, guys.

Still a bit more to do but I'll refer back here once I get to that point. Still need to find some brake shoes for the 42-6313 full width hub.