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Discussion Starter · #1 ·
Hi all,

I’m about to attempt my first bleed of a set of sram guide brakes (gasp) after only ever bleeding shimanos. Is the shimano bleed block the same thickness as the sram one? I’ve a variety of shimanos, do I have to get a specific sram one?

Thanks in advance,

C
 

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Probably doesn't matter if the bleed block is the same width, as long as it's not too wide. It is 1mm more narrow, so what. Pads will still be secured from movement during lever pull, right?

Am I missing something?
 

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Probably doesn't matter if the bleed block is the same width, as long as it's not too wide. It is 1mm more narrow, so what. Pads will still be secured from movement during lever pull, right?

Am I missing something?
A bleed block is used without pads. Thickness is fairly important, because when bleeding you want to make sure the pistons are fully retracted. If they move, you're apt to get a sloppy bleed. Probably too much fluid if the bleed blocks are too thin.

That said, I have no idea if SRAM's bleed blocks are the same thickness as Shimano's. I went out and measured my own bleed blocks and my Hayes blocks are almost 1mm thicker than the ones I use for Shimano brakes. I've not bled SRAM brakes, though.

Wouldn't hurt to remove the pads from your SRAM brakes and see about stuffing your existing blocks in there to see what the fit is like. If it's snug enough, I don't see why it wouldn't work.
 

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You can probably jam something in there in addition to the shimano blocks if they're too narrow, you want to fully retract the piston and keep them from coming out as you're putting pressure into the system. You'll also want to pay attention as to how many pistons your brakes have (2 or 4) and for which brakes the bleed block is for ( 2 or 4 piston brakes).
 

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Uncharacteristic of my usual anal attention to technical detail, I've often used Shimano blocks to bleed Sram Brakes. Also uncharacteristic of my analness, I've done it without any blocks. I bleed the system, close the caliper bleed port, push the piston all in letting excess fluid go into the lever syringe. Using this method, don't push so hard during bleeding that you push a caliper piston out...which is messy but not the end of the world. Anything you can stick in there to help prevent that from happening is helpful.
 

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Discussion Starter · #6 ·
Hi, thanks for the replies, seems like might be worth a shot with a shimano block and a few bits of cardboard. Will experiment.

Thanks again!

C
 

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I have both the yellow Shimano bleed blocks and the red ones from Avid. They are all 10mm thick.
there you go. My Hayes ones are a touch over 11mm thick. At this point, I think the important part that remains is that they fit into the caliper width-wise and that the retention pin hole lines up so they can be kept in place while you work.
 

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Bleed blocks are fine when everything is new, but after stuff starts to wear I just stick a couple pieces of paper or a single thin plastic shim between the pad and rotor. When the bleed is done close the top bleed port and pressurize the caliper just a bit to make sure everything is tight, but not dragging. (SRAM Guide brakes)
 

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I'm no expert on bleeding, but recently did a bleed on some SRAM Level TLMs using the recommended SRAM bleed block (a bit over 11mm thick). When finished the lever would travel just about down to the bar even after repeated actuation. Eventually I fabricated my own block that was a little bit thinner (about 9.5mm) repeated the bleed and everything now works fine with a comfortable lever travel. Maybe I cheated and have excess fluid in the system, but it does seem to work.
 

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Despite my cavalier attitude in post #5 above, I'll point out two reasons to remove the pads and use a block:

1. It resets the pistons and ensures the specified amount of fluid is in the system. More is not better.
2. It's much harder to contaminate and ruin the pads with brake fluid if they're not in the caliper.

If the brakes don't work properly after being bled with a block, something is wrong that should be diagnosed and corrected...or not. It's your choice since it's your ass on the bike.
 
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