Rear brake torque arm mod

Niterunnr

Active Member
Joined
Jul 2, 2019
Messages
104
Location
Irvine, CA
Howdy folks,
All this time at home likely has many of us doing projects.

Does the tight torque arm clearance bother anyone else? I wonder what problems could come from moving it outward? Maybe tack weld a sleeve to reinforce the opposite end? How much torque does this thing really experience anyway? Is there a replacement part? If anything I would go narrower, but I can see debris coming into contact here.6D1BFD14-460E-4E78-83D3-D827DE0E6642.jpeg
 

RCinNC

Well-Known Member
Joined
Aug 30, 2014
Messages
2,816
Location
North Carolina
I don't see the point in modifying it; I've never had any issues with the clearance between the link and the tire.

One problem I can see of moving it to the outside of its current position is that you'd be altering where and how the force is being applied to the brake caliper and the mounting point on the swingarm. Instead of the force being centered on both those points it would now be offset, and would be applying the load differently to those points. If you push on a rod mounted to the side of an eyelet, you're actually going to be imparting a twisting force on the eyelet, because the bolt running through the eyelet will act like a lever. It might not amount to anything, but it's not the load that those points were engineered for.
 

Bokerfork

Active Member
Joined
Jul 15, 2019
Messages
106
Location
Saint George, Utah
Let's see. How much torque does this arm experience? The best way to measure this is to disconnect it, drive down the hiway at about 70MPH and stand on the rear brake while your buddy, riding pillion, reaches down and tries to hold the caliper while the ABS starts chattering. IOW, a lot.

I know that over on the FJR Forum, many a Darksider used a modified arm in order to gain clearance for their tires. If this is something you're looking for you might want to do a quick search of their site. It's doable, I'm just not sure your method will give you the requisite strength you're looking for.
 

Jlq1969

Well-Known Member
Joined
May 5, 2018
Messages
1,749
Location
Argentina
Howdy folks,
All this time at home likely has many of us doing projects.

Does the tight torque arm clearance bother anyone else? I wonder what problems could come from moving it outward? Maybe tack weld a sleeve to reinforce the opposite end? How much torque does this thing really experience anyway? Is there a replacement part? If anything I would go narrower, but I can see debris coming into contact here.View attachment 65168
Why did you modify the torque arm? The one shown in the picture is not the original and it is seen to be noticeably wider than the OEM. Not to mention that it is perforated, surely to relieve it. I see that mine doesn't have those holes
 
Last edited:

Sierra1

Well-Known Member
Joined
Nov 7, 2016
Messages
14,819
Location
Joshua TX
My only problem that I have with it is what Mr. Bokerfork mentioned....clearance. If it wasn't for the limited clearance, I'd have more rubber on the rim....bike, not car though. But, since she works so well "as-is", it's not worth the time & effort to make a modification, for those rare times that I want to lean over a little more.
 

EricV

Riding, farkling, riding...
2011 Site Supporter
2012 Site Supporter
2013 Site Supporter
2014 Site Supporter
Joined
May 22, 2011
Messages
8,227
Location
Tupelo, MS
A. There is no problem with the "tight clearance". There is quite a bit of clearance and virtually no reports of debris caught there. This is in part because of the overall design of the bike.

B. What TallPaul pointed out. If you mount it this way you're greatly diminishing the strength.

C - @Jiq1969 - It's not modified, just mocked up that way. And US bikes do have holes in the arm. Note that the hole for the hose tie is a smaller diameter than the other holes.

D. Darksiders on the FJR forum us steel or stainless steel. (I'm Darksider #1 ) I strongly recommend 3/16" thick x 3/4" bar if you choose to do this. The Darksiders do it because of the much wider 205/50R17 tires being used. If you choose to do this, use your OEM part as a template for the holes, remember that the hole for the hose tie is smaller than the bolt holes and round off the ends for necessary clearance so it doesn't bind on the swingarm end when moving up and down with suspension movement. And use shorter bolts.
 

Niterunnr

Active Member
Joined
Jul 2, 2019
Messages
104
Location
Irvine, CA
Lots of great replies, thx all.
I agree the strength would be reduced and was thinking of applied torque from only the linked brakes, but after some thought, I plan to mod the abs for off road and lock up ability. I’ve simply never seen such a tight clearance and so it bugged me as there seems no reason for it. As Eric pointed out, the arm is oem, I just flipped it over for the photo revealing the holes on the other side.
I’ll leave it alone for now :)
 

WJBertrand

Ventura Highway
Joined
Jun 20, 2015
Messages
4,516
Location
Ventura, CA
Looks like the caliper could twist being supported off-center like that. Best case - uneven pad wear, worst case - stuck, broken parts?


Sent from my iPhone using Tapatalk Pro
 

EricV

Riding, farkling, riding...
2011 Site Supporter
2012 Site Supporter
2013 Site Supporter
2014 Site Supporter
Joined
May 22, 2011
Messages
8,227
Location
Tupelo, MS
Looks like the caliper could twist being supported off-center like that. Best case - uneven pad wear, worst case - stuck, broken parts?
The torsion arm does not supply rigidity to the caliper, only keeps it in place to prevent rotation. The caliper mount itself is quite rigid and well designed to maintain alignment during braking.

I have seen this done on an FJR once, and highly discourage it. That person used spacers on the inside of the torque arm and placed the nuts on the outside as normal, with the entire arm offset to the outside using the OEM bolts. It was a field emergency modification in order for them to get back on the road where no moto tires were available, but a CT was and time was critical. Later inspection of the pads showed no indication of un-even wear.
 

Don in Lodi

Well-Known Member
Founding Member
2012 Site Supporter
2013 Site Supporter
2014 Site Supporter
Joined
Feb 1, 2011
Messages
5,780
Location
Lodi Kalifornia
As noted, that caliper arm is a huge chunk of alloy, it's not going to twist. A nice piece of stainless for the torque arm would look good. The only issue I see with that is your style of riding; is there a chance of something knocking it asque, a branch, a rock.
 
Top