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-   -   R80G/S upside down brake conversion (http://www.advrider.com/forums/showthread.php?t=548403)

One Less Harley 02-06-2010 03:44 PM

R80G/S upside down brake conversion
 
I had noticed Nathan's (Boxerworks) G/S at the Georgia Mountain Rally last year and asked him about the upside down lever on his bike. He said it was easy to do, take a grinder and match the cam profile to the back side of the ears. So the seed was planted......

Before picture stock setup

http://i151.photobucket.com/albums/s...m/IMG_0395.jpg

Stock brake location

http://i151.photobucket.com/albums/s...akesetup-1.jpg



Remove brake cam and make a cardboard tracing of the original
http://i151.photobucket.com/albums/s...m/IMG_0374.jpg

Cut out cardboard and flip it over like so...
http://i151.photobucket.com/albums/s...m/IMG_0375.jpg

Spray paint to get new profile
http://i151.photobucket.com/albums/s...m/IMG_0377.jpg

Here's the profile.
http://i151.photobucket.com/albums/s...m/IMG_0378.jpg

Start cutting w/ and angle grinder and cutoff wheel. Here's the 1st cut. Hopefully before cutting I don't have to tell you to remove the two o-rings...do I??
http://i151.photobucket.com/albums/s...m/IMG_0379.jpg

...And more. Proceed slowly and hold the grinder flat.
http://i151.photobucket.com/albums/s...m/IMG_0380.jpg

Keep grinding till it looks something like this, this still needs a little work
http://i151.photobucket.com/albums/s...m/IMG_0381.jpg

I was probably paranoid about weakening the cam as there wasn't as much material on the back side. See drawing.
http://i151.photobucket.com/albums/s...IMG_0381-1.jpg


So I added metal w/ the MIG welder then smoothed down the welds.
http://i151.photobucket.com/albums/s...weldedcam1.jpg

http://i151.photobucket.com/albums/s...weldedcam2.jpg


I then smoothed out the cam where the brakes will sit with a 120 grit sanding pad on a pneumatic angle grinder
http://i151.photobucket.com/albums/s...m/IMG_0383.jpg


Then inserted the cam in the final drive, you will have to flip the brake shoes over and relocate the springs to the opposite side.

I did notice that the springs may touch the OUTER edge of the FD seal. If this was on the inside edge I would be concerned. The reason for this is that the back bone of the brake shoes favors one side. A little hard for me to put into words but you'll see what I mean.
http://i151.photobucket.com/albums/s...idedowncam.jpg


Put the wheel on, not necessary to bolt it in place, you will have to adjust the brake arm to get it in the correct location. You'll have to fiddle with the arm to position it correctly. Bolt the wheel on then adjust the brakes. Ride the bike a bit to make sure the arm doesn't need to be moved. Once you get it in the right location mark the lever location on the cam with a center puinch.
http://i151.photobucket.com/albums/s...m/IMG_0400.jpg
http://i151.photobucket.com/albums/s...m/IMG_0399.jpg


BubbaZanetti 02-06-2010 03:53 PM

it would have been easier to just flip the transmission upside down.:deal :lol3

One Less Harley 02-06-2010 04:16 PM

I really wasn't hard to do, just tinkering a bit.

Flipping the tranny....Now there's a thought...... Humm... with an upside down tranny maybe the reverse light would be easier to replace, hey it wouldn't leak either!!!

One Less Harley 02-28-2010 07:29 PM

I've ridden the bike with the upside down lever, what I don't like about it.

The brake gets tighter when pulled off the center stand and weight put on the rear wheel.

also when ridding and putting pressure on the brake pedal, the brakes feel like they are out of round. I'm not sure why this is happening, maybe the cam shape isn't quite right? To me it feels as if the brake shoes are ridding up and down the cam.

A third problem- even though I tried to mimic the profile of the cam, it is not shaped quite right. The off shape keeps the brake from engaging solidly.

So, my conclusion is to remove the cam and return the lever to the stock location.

BMW Fanatic 12-11-2013 01:14 AM

Upside down rear brake cam conversion.
 
I also wanted to do this. Please put a couple of pics back on so I can see. How did you route the "pull rod" past the shock ? Or did you use a cable ? If you just ground 2 "mirror image" cams onto the back of the existing cams, did you weld up the original cam faces for strength ?

One Less Harley 01-14-2014 08:08 PM

sorry no longer have the picts. I was unhappy with pulsing while braking and went back to the original setup.

I traced a pattern of the cam and and made a template then flipped the template over on the cam and cut the cam to the new profile. Hope this explains it well enough.

Airhead Wrangler 01-14-2014 08:44 PM

It seems that later brake cams are usable for this without any modification, although I've never tried it. The later ones are just flat.

This:
http://jowls.smugmug.com/Other/HPN-B...P1000785-L.jpg

...instead of this:
http://jowls.smugmug.com/Other/HPN-B...P1000782-L.jpg

Jim K in PA 01-15-2014 08:50 AM

Quote:

Originally Posted by Airhead Wrangler (Post 23223735)
It seems that later brake cams are usable for this without any modification, although I've never tried it. The later ones are just flat.

Hmmm - I wonder though if you would get proper leverage on the early style shoes with that later cam. I think the profile of the casting on the end of the shoe changed along with the cam profile. If you use the later cam, you probably have to use the later shoes as well. But, it may make for an easier conversion.

I would like to do this lever flip as well on my '79. I have a spare early cam and rod, and was thinking about pressing off the cam and flipping it, rather than re-grinding the profile.

Beemerguru 01-15-2014 07:03 PM

I've built 3 of them...but did it a little differently..I cut the cam off, reversed it and had it rewelded back together...

Not me but a local machine shop that does all my crazy welding request.

Never had an issue with pulsing and with proper adjustment and good shoes, no issues with binding

One Less Harley 01-15-2014 07:53 PM

If I remember right I had to swap the shoes around too..for some reason???

I may have to look into doing it that way...

greentreephrog 01-16-2014 07:34 AM

As a matter of interest, are these us conversions being carried out because of some problem being experienced (perhaps in certain conditions), or is it more a matter of it just looks to be a logical modification to improve clearance?

Box'a'bits 01-16-2014 01:31 PM

Looks, & also ground clearance. However most that do this wouldn't ever suffer issues - so it's mostly for looks. :D

Jim K in PA 01-16-2014 02:11 PM

What Box'a said . . . :D

Personally, I am doing to to get the cast brake arm up out of harms way. I have laid mine down in some rocks, and if a "simple" relocation can save my bacon when I am on the TAT, I am all for it.

https://lh6.googleusercontent.com/-w...8/s640/BD3.jpg

hardwaregrrl 01-16-2014 02:37 PM

The only problem Ive ever had from crashing HARD on the right side was a bent rod......I swapped a cable for the rod and have had no problems since. Unitl I actually brake the arm, I don't see a reason to flip.

Dmaster 01-16-2014 04:30 PM

I only banged off the adjustment nut once, its a bit bend now but I don't care.
Carry a spare one and a nut is way more easy (I don't even have one lol), and if you want to use the original suitcases you can't flip it up. It wil bang into it. (well at least if I flip mine up)
https://scontent-a-ams.xx.fbcdn.net/...80057466_n.jpg


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