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1 hour ago, RedRider3141 said:

Actually those clamps brought me basically right to the beginning of his video. I'm working the spokes now. It's getting closer and closer, but admittidally I've never done this for more than ~3/16" out of round. 

The clamps were genius.  

 

I've seen the meth of leaning the wheel against a rock and standing on the high-sides.  With you having done that before spoke truing, you will end up with more even tension.

Just watch out for introducing a hop.  As the guy in the video says, loosen one side equal number of turns before you tighten the other side.

Edited by AntonioGG
Added requisite Clamps video.

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Anyone ever seen this issue before with shimano brakes? When I pull the brake lever quickly, the lever feels firm. When I pull slowly, the lever goes to the bar. The brake will not lock the rear wheel when riding unless I pull really hard with two fingers. 

Not my bike so I don’t know the maintenance history. Just putting some feelers out before I bleed/start taking things apart. My initial guess is a bad master cylinder  

Video

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That is bizarre! I guess it could just be messy junk in the hose and cylinder. Still, I'd start by pushing out and lubing the pistons up real good with mineral oil. Then do a standarrd caliper up bleed (making sure to push new oil all the way through to the funnel) and see if the oddness goes away. 

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If you pull it quick and hold will it pull all the way to the bar? I'd guess that fluid is bypassing the piston in the master cylinder. I'd plan to replace the master cylinder/lever assembly.

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4 minutes ago, Big_papa_nuts said:

If you pull it quick and hold will it pull all the way to the bar? I'd guess that fluid is bypassing the piston in the master cylinder. I'd plan to replace the master cylinder/lever assembly.

No. When I pull quickly and hold the lever remains firm. I wish I could order replacement parts but with Shimano your only option is to replace the entire lever. 

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22 minutes ago, Barry said:

That is bizarre! I guess it could just be messy junk in the hose and cylinder. Still, I'd start by pushing out and lubing the pistons up real good with mineral oil. Then do a standarrd caliper up bleed (making sure to push new oil all the way through to the funnel) and see if the oddness goes away. 

Thanks! Exactly what I had in mind. I’m hoping the master cylinder piston just needs a good cleaning and lube.

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8 hours ago, Big_papa_nuts said:

If you pull it quick and hold will it pull all the way to the bar? I'd guess that fluid is bypassing the piston in the master cylinder. I'd plan to replace the master cylinder/lever assembly.

Just to save WLemke some trouble, master cylinder assemblies for Shimano levers are not available unless you want to take a chance on some weird AliExpress bits. You have to replace the whole lever if that is the case. I've tried.

(Looks like you figured that out though.)

 

Edited by mack_turtle

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21 minutes ago, mack_turtle said:

Just to save WLemke some trouble, master cylinder assemblies for Shimano levers are not available unless you want to take a chance on some weird AliExpress bits. You have to replace the whole lever if that is the case. I've tried.

(Looks like you figured that out though.)

 

His brakes look to be 501s. If this is correct the part number for the master cylinder/lever assembly would be EBLMT501RL, UPC 689228686588, with a retail of $50 or less. 

I didn't look as far as just the lever blade but those are available for most modern Shimano hydro brakes.

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Internals looked fine and wasn’t really dirty at all. Gave the system a bleed and the issue persisted. 
 

found our from the guy who owns this bike that the lever is less than a year old. He is having it warrantied. 

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21 minutes ago, WLemke said:

Internals looked fine and wasn’t really dirty at all. Gave the system a bleed and the issue persisted. 
 

found our from the guy who owns this bike that the lever is less than a year old. He is having it warrantied. 

if the seals are worn, I would think you would not be able to detect the wear with the naked eye. maybe if you had a new, unworn seal next to it to compare.

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24 minutes ago, WLemke said:

Internals looked fine and wasn’t really dirty at all. Gave the system a bleed and the issue persisted. 
 

found our from the guy who owns this bike that the lever is less than a year old. He is having it warrantied. 

I'd be interested to know if genuine Shimano brake fluid was always used in the system. According to Shimano other's "compatible" fluid can lead to system failures, but the internet insists "it'll be fine".

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I've used Tekrtro mineral oil in the past with no issue. There's a crass joke somewhere about it all being pink, I think. 

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If there's no fluid leaking from the system anywhere it has to be the seal on the plunger in the lever, right?  This kinda makes sense too.  All kinds of seals will leak at low pressure and then seat when the pressure gets high enough.

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It might be that the brakes are an older production date and is one of the batches of Shimano brakes that had the pump up issue.

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Excess cornstarch in the brake fluid and now you have a non newtonian fluid. Reduce your cornstarch levels to below the manufacturer recommended amount. /s

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18 minutes ago, taco_junkie said:

Excess cornstarch in the brake fluid and now you have a non newtonian fluid. Reduce your cornstarch levels to below the manufacturer recommended amount. /s

I call total bullshit on this. You don't put cornstarch in your brake lines, it will gunk up the flux capacitor.

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While we're on the subject of brakes. I just installed TRP HY/RD on my gravel bike to replace the Spyres which were basically a small step up from rim brakes. Only two rides into them but the stopping power and modulation are much better than the Spyres were. The only issue now is the length of the rear brake cable and the amount of compression it has. The rear lever travels a greater distance to get the same amount of stopping power as the front. Looking into some compression less cable housing. The bike came with Jagwire cables and housing,  I would assume that as it came with mechanical discs it is the Pro housing which is "Compression less". Unfortunately not compression less enough for me.

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So what do you do when a nob rips off of an otherwise good tire? I'm tempted to just take my chances for a while on my local trail. 

20200927_163201.jpg

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