Front drum brake fitment...

[beer9000]

Hey there, new to the forum as an official user but VERY guilty of reading without participating. Have gotten out of some real tough ones which were made simple by all you on here plenty of times.

So, I have a pretty simple question I'm hoping to get some guidance on. Theoretically, could you run any make/size brake drum on any make/size wheel provided you have the right length spokes, and matching axle sizes? or is there more to it than that? Can I lace any old drum to the wheel I've already got? Any easy(ish) to find drums for 3/4" axle?

I've always just run no front brake, but I've decided to run a drum this time on my hd springer, hand shift + foot clutch xs650.. mostly just don't want to leave my fate in the hands of that famous yamaha rear drum when it comes time to stop on a hill.. and DEFINITELY don't want to run a disc!!

[TriNortchopz]

What is wheel you already got? You can lace a drum to it depending on the spoke layout - how many spokes in your rim? Are you set on keeping the rim (wheel)? How about posting a few pics of what you got. easiest option is to just grab another wheel and get bearings to fit your 3/4" axle...do you know what type of drum you want - or what you don't want? what about an early XS ('70-'71) to go with your XS?

A few ideas here:
Thread: XS650 front drum

http://www.chopcult.com/forum/showthread.php?t=5998

Here is a list of axle sizes; lots of options using 17mm front axle, only 2mm smaller than 3/4" (19mm) so bearing swap should be easier as bearing OD is probably closer: http://www.dotheton.com/forum/index.php?topic=20952.0

[Guest]

You can get away with a lot but probably not all. Of course jap stuff is 36 hole and pretty much everything else is 40.

Alignment varies a bit, I have a triumph rim laced to a Harley hub, had to open the rim up a bit and the spokes still have a minor bow to them. Tons of triumph hubs laced to Harley 16s out there.

Easy to find 3/4 drums? 40 hole? Iron heads, big twins and brits.

[beer9000]

Here's what I've got: set-up, balanced, and trued tc bros 21 x 2.15 40-spoke rim with an avon tire, on a moto iron springer. All meant to fit a harley, but adapted to the xs.

My only attachment to this rim and tire is that it's already set to roll. I bought it thinking I was gonna run it without a front brake, but obviously changed my mind. If I can lace something to this one, great! If not, I'm fine with saving this wheel for later.

I've also got the stock xs650 36 spoke rim with tire.


So, I'm gathering that my options are to A. lace a 40 spoke drum to the 21" rim I've already got on, B. lace an old xs 650 drum onto my stock rim and figure out how to make the axle fit, or C. get a whole new wheel with the drum already laced up to fit my 3/4" axle.

It seems like you're right that grabbing a whole new wheel and some 17mm bearings would be the easiest option. Those links are awesome, thank you!

[beer9000]

Ok, good to know that it can and most certainly has been done. My only question left with lacing any drum up to a rim is about the spokes.. Do you need certain length spokes to lace to a certain rim? Seems to me that lacing a drum to a rim would require shorter spokes.. as they're connected from the rim to the outer edge of the drum as opposed to the center of the rim.

[Guest]

You need the correct length spokes for whatever combination you choose. Buchanan’s is very helpful.

[JBinNC]

Lacing disc or spool hub rims to a drum is usually a problem because of the spoke angles, as mentioned above, and it can be a big problem. It's best to have a rim that is dimpled and drilled specifically for the drum to be used. Buchanan's was mentioned above, and they can supply a rim as well as spokes for almost any drum you want to use. Of course, the larger the diameter of the rim, like your 21, the less problem the spoke angles are.

As far as axle size, all drum brake hubs I know of, including the Sportster drums, use metric bearings and axles, or in the case of the Brit drums, a bearing that is smaller than 3/4". But making a custom size axle is not that big a deal. 17mm bearings are still smaller than 3/4", so that is not much help, you will still need an axle.

Jim

[JBinNC]

You will need to run a reaction link from the brake backing plate to the rear leg of your springer. Hopefully it has an anchor point on one or both sides.

Jim

[TriNortchopz]

XS650 front wheel bearings: 6303 2RS KOYO bearing is a Sealed Deep Groove Radial Ball Bearing with a standard radial internal clearance The bearing's dimensions are 17x47x14.

6204-2RS-12 3/4" Bearing is 0.75" inch ID 3/4"x47x14

[JBinNC]

XS650 front wheel bearings: 6303 2RS KOYO bearing is a Sealed Deep Groove Radial Ball Bearing with a standard radial internal clearance The bearing's dimensions are 17x47x14.

6204-2RS-12 3/4" Bearing is 0.75" inch ID 3/4"x47x14

Perfect for his axle. He needs only to bore the backing plate to match (and that needs to be done accurately).

Jim

[kmanator]

You will need to run a reaction link from the brake backing plate to the rear leg of your springer. Hopefully it has an anchor point on one or both sides.

Jim

The backing plate also needs to float or pivot independently during the arc of the rockers or it will break or tear the tab off the springer leg.Telescopic fork brake drums are not designed for this and must be modified by boring out the center axle hole and sleeving it to allow the backing plate to rotate after the axle is cinched down.I run a 21 inch Suzuki dirtbike drum/wheel on a narrow Fury industries springer.

[555]

Early CB450 front hubs are 40 spoke and easily laced to a HD 21" rim. Buchanans can provide the correct spokes. You will still need to size bearings/spacer for the 3/4" axle and bore the brake backing plate to 3/4".

[beer9000]

The backing plate also needs to float or pivot independently during the arc of the rockers or it will break or tear the tab off the springer leg.Telescopic fork brake drums are not designed for this and must be modified by boring out the center axle hole and sleeving it to allow the backing plate to rotate after the axle is cinched down.I run a 21 inch Suzuki dirtbike drum/wheel on a narrow Fury industries springer.

how did you accomplish this? mind posting a pic or 2?

[Guest]

In the Brit forum there’s a lot of posts of a bike called brown sugar. Torch was pretty proud of the brake stay on that.

[TriNortchopz]

I’m the Brit forum there’s a lot of posts of a bike called brown sugar. Torch was pretty proud of the brake stay on that.

Its in the News section too:

Brown Sugar

http://www.chopcult.com/news/articles/brown-sugar.html