Guide RSC Bleed. Changing contact point adjusment before bleed for different feel?

[beejay]

So my question is this;

Has anybody played around with positioning the contact point adjuster in different positions for bleeding?

I found a video online suggesting to set them in the middle position to allow for a better range of adjustment after bleeding.
I've so far just followed SRAM techs advice to turn the adjuster fully away from the direction of the arrow, but find that for the right feel I wind the adjuster back fully the other way after bleeding allowing no further adjustment.
Anyone in RB land given this a go?

 

[Hellyeah]

So my question is this;

Has anybody played around with positioning the contact point adjuster in different positions for bleeding?

I found a video online suggesting to set them in the middle position to allow for a better range of adjustment after bleeding.
I've so far just followed SRAM techs advice to turn the adjuster fully away from the direction of the arrow, but find that for the right feel I wind the adjuster back fully the other way after bleeding allowing no further adjustment.
Anyone in RB land given this a go?

yep, that's how I do it

you can also use smaller bleed blocks............but don't tell anyone:spy:

 

[beejay]

yep, that's how I do it

you can also use smaller bleed blocks............but don't tell anyone:spy:

Excellent, cheers Hellyeah.

It seems that the SRAM instructions set the brakes to the opposite of what you would want.
So would you think I could turn the adjuster to the full opposite of the instructions? or could it cause any harm?

 

[Haakon]

I have Guide RS - I just put a bit of cardboard between the pads to make sure they don't pop the pistons all the way out, and pull the lever into the bar.

They don't retract all the way back and voila - pistons sitting closer together and much less lever travel before the contact point is reached.

I hate having heaps of lever travel...

 

[Nambra]

Thread dig.

I had a crack at bleeding my Guide R brakes on the weekend - following the SRAM video guide on youtube to the best of my ability. My experience differed somewhat to expected and as it was the first time I've tried bleeding Guides (or any hydraulic brake for that matter), I'm keen for feedback from those more experienced. The main problem I had was when I removed the syringes from the calipers, there was a fair loss of brake fluid prior to re-installing the little torx bleed port screw - this leakage wasn't as apparent on the video.

The amount of leakage on the front brake was fairly minor, and despite this, the front brake feels a lot nicer now, and with new metal pads provides good stopping power. The rear brake lost a fair amount of fluid between removal of the syringe and re-installation of the bleed port screw, and the lever just doesn't feel quite right compared to the front brake. Plus, you can hear a squishing noise when operating the rear brake lever - sort of like aerated fluid being forced through an orifice; I suspect that I've lost too much fluid and there is a bit of air in the rear brake or that there is very little oil in the master cylinder.

Can anyone tell me if loss of fluid like this sounds right - or have I messed up the procedure somewhere? I've got enough fluid to re-bleed, but want to make sure I'm doing it right before I go again. Is there any benefit in inverting the bike before removing the caliper syringe, or at least raising it so that the height difference between the caliper and lever is minimal when re-installing the bleed port screws?

As others in this thread also say, following the SRAM instructions seems to leave you with brakes that have a lot of travel before the pads engage on the rotors. I was thinking of measuring the combined thickness of the rotor and pads and then making up a bleed block that thick instead of the SRAM one in the bleed kit which pushes the cylinders out as far as they go. I could also leave the wheel on and pads in, but then I run the risk of contaminating the pads and rotor with brake fluid.

A final note on the 'standard' SRAM bleed kit (got it from CRC) - the short plastic tubes leak fluid at the end where they fit onto the plastic bit that screws into the syringe. It would pay to wrap a bit of fine wire around the tube at that end for a better seal.

 

[Elbo]

Thread dig.

I had a crack at bleeding my Guide R brakes on the weekend - following the SRAM video guide on youtube to the best of my ability. My experience differed somewhat to expected and as it was the first time I've tried bleeding Guides (or any hydraulic brake for that matter), I'm keen for feedback from those more experienced. The main problem I had was when I removed the syringes from the calipers, there was a fair loss of brake fluid prior to re-installing the little torx bleed port screw - this leakage wasn't as apparent on the video.

The amount of leakage on the front brake was fairly minor, and despite this, the front brake feels a lot nicer now, and with new metal pads provides good stopping power. The rear brake lost a fair amount of fluid between removal of the syringe and re-installation of the bleed port screw, and the lever just doesn't feel quite right compared to the front brake. Plus, you can hear a squishing noise when operating the rear brake lever - sort of like aerated fluid being forced through an orifice; I suspect that I've lost too much fluid and there is a bit of air in the rear brake or that there is very little oil in the master cylinder.

Can anyone tell me if loss of fluid like this sounds right - or have I messed up the procedure somewhere? I've got enough fluid to re-bleed, but want to make sure I'm doing it right before I go again. Is there any benefit in inverting the bike before removing the caliper syringe, or at least raising it so that the height difference between the caliper and lever is minimal when re-installing the bleed port screws?

As others in this thread also say, following the SRAM instructions seems to leave you with brakes that have a lot of travel before the pads engage on the rotors. I was thinking of measuring the combined thickness of the rotor and pads and then making up a bleed block that thick instead of the SRAM one in the bleed kit which pushes the cylinders out as far as they go. I could also leave the wheel on and pads in, but then I run the risk of contaminating the pads and rotor with brake fluid.

A final note on the 'standard' SRAM bleed kit (got it from CRC) - the short plastic tubes leak fluid at the end where they fit onto the plastic bit that screws into the syringe. It would pay to wrap a bit of fine wire around the tube at that end for a better seal.

Just a quick reply, you may have left some pressure in the line depending on which syringe you removed first and whether or not you had pushed or pulled it prior to removal. I tend to push fluid up from the caliper to the lever. On taking the first syringe out, I would want to be compressing that syringe just prior to removal to neutralize pressure in the line + effects of gravity, otherwise you'll have more fluid flowing out freely. But yeah, if you've got built up pressure in the line, fluid will come out when removing the syringe, but it shouldn't matter too much as long as it stays close to the bleed screw and air doesn't get in. Hope that makes sense. Did you do all the lever isolating/pad adjustment dial turning, etc? (I haven't done Guides myself, but assuming they're similar to Elixirs)

 

[The Duckmeister]

Normally if the top of the system is properly closed, vacuum pressure stops the fluid falling out of the caliper, same as holding your finger over the top of a straw. If you have got a bit of air in there, with a bit of luck it's still floating about in the caliper, so you don't need to do a full re-bleed.
Try this:

Remove caliper from bike. Attach partially-filled syringe to the caliper, and leave the top port closed. Hold the caliper so the bleed port is at the highest point and above at least a short section of hose - doesn't have to be above the brake lever. This will ensure any bubbles are just below the bleed port. Gently push fluid into the caliper, then release. Any stray bubbles should come up into the syringe as you release the pressure. GENTLY pull a bit of reverse pressure on the syringe to suck any more tenacious bubbles out. I stress do this gently, because if you're too forceful you'll overpower the master seals & suck air in up the top. Repeat these processes a couple of times, until you're sure there's no more air coming out. Then while still keeping the bleed port at the highest point on the caliper, remove the syringe & replace the plug.

If you still have pressure problems, repeat the same process at the lever.

 

[Nambra]

Just a quick reply, you may have left some pressure in the line depending on which syringe you removed first and whether or not you had pushed or pulled it prior to removal. I tend to push fluid up from the caliper to the lever. On taking the first syringe out, I would want to be compressing that syringe just prior to removal to neutralize pressure in the line + effects of gravity, otherwise you'll have more fluid flowing out freely. But yeah, if you've got built up pressure in the line, fluid will come out when removing the syringe, but it shouldn't matter too much as long as it stays close to the bleed screw and air doesn't get in. Hope that makes sense. Did you do all the lever isolating/pad adjustment dial turning, etc? (I haven't done Guides myself, but assuming they're similar to Elixirs)

I think you're right in that bleeding Guides and Elixirs is a similar process. I more or less followed the SRAM youtube vid (https://www.youtube.com/watch?v=nqdp7a7FXe8) to the letter, and the lever isolation is done right after you push fluid through the caliper up to the lever. Guide R's don't have any pad contact point adjustment (only RSCs or Ulitimates do AFAIK). I've just come across an alternate bleed video (https://www.youtube.com/watch?v=Oid_MTcW1P4) which does things quite a bit differently, and I can see in that video that when syringes are removed from the bleed ports on calipers, there is a fair bit of fluid loss - you can see it dripping off the caliper. This is more like it was when I did it, so perhaps it is normal. That second video also has a step where the caliper syringe is used to deaerate the system prior to bleeding, and you can see that old fluid gets pulled into the syringe and mixes with the new fluid. The dude then bleeds the brakes with this contaminated new fluid - the SRAM instructions certainly don't show that step.

 

[Nambra]

Normally if the top of the system is properly closed, vacuum pressure stops the fluid falling out of the caliper, same as holding your finger over the top of a straw. If you have got a bit of air in there, with a bit of luck it's still floating about in the caliper, so you don't need to do a full re-bleed.
Try this:

Remove caliper from bike. Attach partially-filled syringe to the caliper, and leave the top port closed. Hold the caliper so the bleed port is at the highest point and above at least a short section of hose - doesn't have to be above the brake lever. This will ensure any bubbles are just below the bleed port. Gently push fluid into the caliper, then release. Any stray bubbles should come up into the syringe as you release the pressure. GENTLY pull a bit of reverse pressure on the syringe to suck any more tenacious bubbles out. I stress do this gently, because if you're too forceful you'll overpower the master seals & suck air in up the top. Repeat these processes a couple of times, until you're sure there's no more air coming out. Then while still keeping the bleed port at the highest point on the caliper, remove the syringe & replace the plug.

If you still have pressure problems, repeat the same process at the lever.

Cheers Duckmeister, I'll give that a go - it makes a lot of sense and sounds simple. I thought that vacuum pressure would prevent fluid from falling out of the caliper too and I didn't realise that I needed to be careful in pulling reverse pressure either.

 

[Nambra]

Just thought I'd report back with an update for the benefit of others. This is my rear brake.

I did try your suggestion Duckmeister, although it resulted in further fluid loss at the caliper when attaching and removing the syringe and subsequently the brake lever would travel to the bar without brake engagement. Obviously I needed to add more fluid so went back to square one, syringes at both ends, but as the fluid in the system was new, I didn't worry about a full flush, and only had a 1/4 of a syringe full of fluid at the caliper (enough to top up the brakes) and only a tiny bit in the lever syringe to provide a good seal and not let air in.

I then pushed fluid from the caliper up to the lever and then in reverse back to the caliper several times, noticing that air bubbles were being expelled at each end as the fluid was cycled.

The top syringe was then locked, the brake lever pulled to the bar and held with a rubber band, and the caliper syringe used to evacuate any remaining air, which there didn't appear to be much of compared to my first bleed attempt, possibly as a result of having pushed fluid back and forth.

The process was pretty much per SRAM instructions after that, push the lever back out with the caliper syringe, lock the caliper syringe and remove it and reinsert the caliper bleed screw, then unlock the lever syringe and pull any air out of the lever end, pressurise / equalise, operate the lever a few times to release more air, etc. then remove the lever syringe and reinstall the bleed port screw, clean up, fit pads and wheel and done.

The rear brake definitely feels a lot firmer now, and there is no squishy noise at the lever either. I think this time around, I lost far less fluid when attaching and removing syringes, and also did a better job of removing air from the system.

I can see the advantages of the RSC lever with the contact point adjustment - you do end up with a fair amount of lever travel before brake engagement when you bleed with the full width bleed block.

 

[blacksp20]

I'm not sure that the Avid instructions are correct re: contact point adjustment. I recently bled my Elixir CR's as per Avid instructions with the contact adjust wound all the way into the lever (opposite to the arrow). After the bleed, if I adjust the pad contact adjuster so the lever requires less pull, I can pull the lever all the way to the bars with no pad contact at all.

Has anyone bled elixirs with the pad contact opposite to what Avid says?

 

[betadine]

RSCs contact point half way

I'm not sure that the Avid instructions are correct re: contact point adjustment. I recently bled my Elixir CR's as per Avid instructions with the contact adjust wound all the way into the lever (opposite to the arrow). After the bleed, if I adjust the pad contact adjuster so the lever requires less pull, I can pull the lever all the way to the bars with no pad contact at all.

Has anyone bled elixirs with the pad contact opposite to what Avid says?

Not elixirs but following this thread I bled my RSC with the contact point dial half way and it made a massive difference. It actually left me with the right range of contact point adjustment post the bleed. By that I mean that I could wind the dial and end up with zero throw or back the other way with too much.

Now have the RSCs dialled with the exact feel that I was after. Something I couldn't achieve when I followed the SRAM video instructions.

 

[adrian.gab]

I've been doing this for years i.e. doing the opposite of what's in the video and today i am about to bleed a new set of brakes after trimming and decided to Google it to see if others do the same and yes, others do. I like a really short dead band and following sram's instruction gives me nothing but a huge long lever throw.

 

[SOTTA]

Not Guides, but I assume similar/same procedure. I recently bled a set of Code RSC's after shortening cables.



I followed the SRAM instructions to the letter and ended up with what I'd call an average bleed with a lot of free throw.



I looked online and fount a YouTube clip of Troy Brosnan 's mechanic doing the brakes on his race bike. I followed that and got a much better result.



The second time I had the pad contact wound all the way out during the bleed.