Rear brake master cylinder mount. Has it been broken?

Don Thuren

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Bend, Oregon
#1
Morning all!

So I was putting new footpegs on, and when poking around looking at how the rear brake master mounting is designed, that seems a SUPER weak area. I bet even a decent stick wedged between the pedal and side case could snap it...

Am I nuts? Has anyone broke this area? Looks like it's not going to be fun to replace if broke...

Thoughts?
 

Don Thuren

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Bend, Oregon
#3
Interesting!!!

I have an idea to beef this area up... I feel like I don't want to snap this off, and I'm often riding through crappy terrain.

Does anyone have the actual Alta CAD files for reverse engineer from?
 
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475
Location
Altoona, PA
#4
Interesting!!!
I have an idea to beef this area up... I feel like I don't want to snap this off, and I'm often riding through crappy terrain.
Does anyone have the actual Alta CAD files for reverse engineer from?
I think if we were able to get any IP we would have gotten the firmware code. However, we have some members here with access to photo modelling software.
 

OneLapper

"You don't *really* need the water pump...."
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#6
Yup. Broke mine. Alta claimed it never happened before. Of course that wasn’t the case.

I modified a new gear box cover by welding a plate on it to mount the foot brake to. It works.
 

Don Thuren

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Bend, Oregon
#8
Yup. Broke mine. Alta claimed it never happened before. Of course that wasn’t the case.

I modified a new gear box cover by welding a plate on it to mount the foot brake to. It works.
If the moto stays on a moto track, I guess it would be rare to break it except for a fluke crash, but if off-road with sticks/logs/rocks/etc it's damn vulnerable....
 

Don Thuren

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Bend, Oregon
#11
I have a brace 3d printing to test fit so I can make some simple machined aluminum bolt on braces for this area, should be sweet!

Bolts to the 14mm linkage bolt for it's main strength. I'll snap a picture of the 3d printed part once it's done, if it fits..
 

Don Thuren

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Location
Bend, Oregon
#12
Test part fits! I'm going to machine a few of these up from 7075 Aluminum if anyone wants one. Might take me a few weeks as my machines are backlogged but I'll get it done...

The 14mm x 1.5 long linkage bolt threads directly into my part, which replaces the nut.

Bolt my Alta's with 100 miles on them, came with that bottom hanging pedal height adjuster mount that hangs down bent, and this will brace that too..


ALTA BRAKE SUPPORT.jpg
 

rayivers

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Location
CT, USA
#13
Looks nice! I'd buy one whenever you get around to making them. I just looked at mine - didn't realize how much leverage the MC/pedal mount had on that lower frame boss.
 

Trialsman

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Pittsburgh
#14
I really had never heard of this being a problem nor thought it was. After this picture of your prototype I went down to look at my two EXRs and guess what? One of the two had the bottom bracket bent. I guess I have a project to machine tomorrow. Thanks for the heads up.
 

Trialsman

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Pittsburgh
#16
If it were not for the fact I am leaving for Georgia to ride the EXR before you get your machines freed up, I would be down for two. Thanks again for spotting the problem and finding a solution. This, once again, shows that everyone's observations, input, and creative solutions are important as we run lower on available parts. Good work!
 

Don Thuren

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Bend, Oregon
#18
I really had never heard of this being a problem nor thought it was. After this picture of your prototype I went down to look at my two EXRs and guess what? One of the two had the bottom bracket bent. I guess I have a project to machine tomorrow. Thanks for the heads up.
That's why we have these machines to make cool functional stuff!
 

OneLapper

"You don't *really* need the water pump...."
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#20
What makes you say that?
That's what Rick told me at the time. No one at Alta had seen this damage / break before.

I was racing the bike when it happened, shit happens. I low sided the bike in the woods, and must have gotten it *just* right to snap that boss of the RBH.

It's all fine now.
 

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