Levo Gen 3 Problem with rear brake sram code rs

[Jorva 1983]

Hello. i am having some problems with the rear brake on my levo.
i noticed this after getting my new frame.
i have bled it with the sram bleed tool myself. and there is no air left in the system.
the lever is very firm with the block from the bleed kit installed. In the rear calliper If there still was air in the system i woud also feel it With the bleed block installed.
but when i instal the brake pads an squeeze the lever in need to turn the reach adjustment to the end to even have a bit of a functioning brake. I also noticed that it was adjusted like that before i started bleeding it. so it must be something i adjusted like that and did not really notice before.
i am almost 100% sure that there is no more air in the system, so i started looking at the rear calliper and the pads. What i noticed is the folowing. When i pull the lever the pistons come out push the pads out (yes thats how they work). But when i release the lever the pistons completely return into the caliper. And this is what causes the strange feel in the lever and the need to adjust the reach on the lever to the end…

so what can cause this? is the spring that is between the pads to strong or bent to cause the pistons to go completely in, causing the long reach on the lever… Or did i mess something up with bleeding it?

i have read more then once that sram brakes are the worst to bleed ect... Thing is i have a set of guide LT brakes on my daily bike, and i have shortend the hoses ect and recently bled those to and these are as firm as it gets almost like the hope brakes on my old mtb. So where do i look now? caliper alignment, the spring…

 

[Mikerb]

did you set the lever at the correct distance from the centre of the bars before bleeding?
Tip of lever 80mm from centre of the bars. That sets the position of the piston in the lever reservoir.

You also have air and too much fluid in the lever syringe. The fluid should be soild from the syringe through to the flex tube.

 

[Jorva 1983]

did you set the lever at the correct distance from the centre of the bars before bleeding?
Tip of lever 80mm from centre of the bars. That sets the position of the piston in the lever reservoir.

You also have air and too much fluid in the lever syringe. The fluid should be soild from the syringe through to the flex tube.

Hello. Yes i did. that is where i noticed that the lever was adjusted to its max.

the picture is after my first try to bleed it. And did the last step in the procedure where you push and pull on the siringe to get the last air out of the system i have tried 2 more times after this but it does not get better…

 

[fraatti]

If you are having problems like described in this video, change brake hose. This was a solution for two different bikes here as well.

 

[Jorva 1983]

If you are having problems like described in this video, change brake hose. This was a solution for two different bikes here as well.

Hello. No this is not the problem i am having. With the bleed block installed in the caliper the brake is firm so there can not be any air in the systemor a leak. The problem starts when i instal the brake pads.

 

[Mcharza]

Maybe there's air in the pistons? It only becomes apparent when the pistons move outwards.
Try this bleeding method, it's much better.

 

[Mikerb]

So the brake block pushes the pistons back flush with the calliper ....unlike the brake pads which together are not as wide. It therefore ususally takes a few pumps on the lever to position the pistons closer to the pads. The pistons only move out and back a short distance.......the amount they are pushed towards the pad is determined by the small volume of fluid in the lever reservoir. Similarly once that pressure is released, the pads are allowed to move back the same distance.
If I understand you correctly, you say that once the pads are inserted..........and you have pumped the lever a few times to set the bite point, the pistons retract all the way back to the calliper??
If I understand you correctly the only way they can do that is with negative pressure in the system (ie sucking back). Never heard of that before but the only thing that I can see might cause that is a lever reservoir overfilled or the diaphragm unable to breathe ( blocked airway in reservoir cover)

 

[Cb750stu]

I use one of these tools to bleed and clean my pistons , you can pump out 1 piston at a time, works really well for a 3D printed bit of plastic

 

[Mikerb]

I use one of these tools to bleed and clean my pistons , you can pump out 1 piston at a time, works really well for a 3D printed bit of plastic

View attachment 108064

...same...been using one for a couple of years now so cleaning and lubing the pistons on the rear calliper is part of my routine everytime I do a mini service.

 

[Jorva 1983]

So the brake block pushes the pistons back flush with the calliper ....unlike the brake pads which together are not as wide. It therefore ususally takes a few pumps on the lever to position the pistons closer to the pads. The pistons only move out and back a short distance.......the amount they are pushed towards the pad is determined by the small volume of fluid in the lever reservoir. Similarly once that pressure is released, the pads are allowed to move back the same distance.
If I understand you correctly, you say that once the pads are inserted..........and you have pumped the lever a few times to set the bite point, the pistons retract all the way back to the calliper??
If I understand you correctly the only way they can do that is with negative pressure in the system (ie sucking back). Never heard of that before but the only thing that I can see might cause that is a lever reservoir overfilled or the diaphragm unable to breathe ( blocked airway in reservoir cover)

100% corect, This is indeed what is happening. Normally when you pull the lever e few times the brake pads woud come closer to the disk but mine dont beqause the pistons retract into the caliper. Its almost like the spring that is on the brake pads is to strong…

i did have some fluid come out of the breather hole on the lever when i was bleeding it. So i gues i wil have a look at that this weekend. Take it apart and see what is going on in there.

and i am also going to clean and lube the pistons on the calliper.

 

[Trickz]

One thing I’ve noticed with the three bikes with code is the back piston never moves as much..it’s almost like the the piston on the outside pushes the disc to the back pad..if you then undo the caliper and re-centre the gap between the pads and start pressing the lever again it will only re-adjust itself to be the same scenario..it’s not by much I’m talking 0.50mm max,what I have is a sram bleed block that pushes the piston all the way back and another that is like 3mm narrower which is still meant to be for the previous sram guide and code..I’m not saying this is right but it works for me..before the bleed with the pads removed I pump the lever till the pistons are exposed obviously not too much but one is always longer,clean the exposed side’s with little bit of the dot5 and leave them wet..push them both back in then use the narrower block in place to do the bleeding process irrespective of how uneven the pistons have come out to meet the block,I’ve never stripped a caliper block or cut one in half to find out but I’m sure there must be like a balancing port that when the pistons are fully back and you bleed it is covered up..hence creating an air gap.

 

[kawamaha]

100% corect, This is indeed what is happening. Normally when you pull the lever e few times the brake pads woud come closer to the disk but mine dont beqause the pistons retract into the caliper. Its almost like the spring that is on the brake pads is to strong…

To prevent the pistons retract into the caliper the brake lever assembly has to work like a check-valve.
Could you swap the front and rear lever just for a test?
For me it sounds like a problem with the rear brake lever assembly not working correctly....

 

[Mikerb]

100% corect, This is indeed what is happening. Normally when you pull the lever e few times the brake pads woud come closer to the disk but mine dont beqause the pistons retract into the caliper. Its almost like the spring that is on the brake pads is to strong…

i did have some fluid come out of the breather hole on the lever when i was bleeding it. So i gues i wil have a look at that this weekend. Take it apart and see what is going on in there.

and i am also going to clean and lube the pistons on the calliper.

...so the diaphragm in the lever is broken. It is a sealed system. The diaphragm is there to enable the volume of fluid to expand as it gets hot without impacting on brake pressure............the tiny hole in the diaphragm cover enable the pocket of air a bove the diaphragm to be at normal atmospheric pressure. You can damage the diaphragm by overfilling/pressurising the lever.

 

[Jorva 1983]

...same...been using one for a couple of years now so cleaning and lubing the pistons on the rear calliper is part of my routine everytime I do a mini service.

...so the diaphragm in the lever is broken. It is a sealed system. The diaphragm is there to enable the volume of fluid to expand as it gets hot without impacting on brake pressure............the tiny hole in the diaphragm cover enable the pocket of air a bove the diaphragm to be at normal atmospheric pressure. You can damage the diaphragm by overfilling/pressurising the lever.

I think it was water that came out not brake fluid. I am going to check it this weekend if i have time for it.

 

[Mikerb]

I think it was water that came out not brake fluid. I am going to check it this weekend if i have time for it.

that would make more sense in terms of the issue you have............if the diaphragm was prevented from expanding by water between it and the cover the pressure in the lever would then push the calliper pistons back. Your issue is definitely with the lever so at least removing the reservoir cover should tell you what is wrong. Be careful , there are some small parts under the outer screw that need tapping out.

 

[Jorva 1983]

Had some time tonight So i had a look at the brake again. And it seems like the pistons on one side of the rear calliper are a bit stuck or dirty. I took a smal screwdriver an pushed the brake pads to one side and pulled the lever a few times and they Came out brake lever feel is firm now like it shoud be. I wil be cleaning and lubing the pistons to’orow evening, and hope to go for a ride in the weekend.
problem solved

 

[Joop E-Bike]

Had some time tonight So i had a look at the brake again. And it seems like the pistons on one side of the rear calliper are a bit stuck or dirty. I took a smal screwdriver an pushed the brake pads to one side and pulled the lever a few times and they Came out brake lever feel is firm now like it shoud be. I wil be cleaning and lubing the pistons to’orow evening, and hope to go for a ride in the weekend.
problem solved

the same problem with a new bike I was struggling myself with it, then I was visiting the dealer and two of the pistons are not moving. They said they want to send it in for warranty three weeks without a bike. I was really pissed and went back full on Shimano XT.

 

[Mikerb]

Certainly on Code callipers and I suspect much the same on any 4 piston calliper, the fluid routing to the outer pistons is somewhat more tortuous than to the inner pistons. That invariably means that any air or water in the fluid is more likely to sit behind those outer pistons and those pistons are more likely to become sticky due to less movement everytime the brake is operated. It is avoided by cleaning and lubing the pistons regularly and, when bleeding the brakes raising the front of the bike and tapping the calliper to enable that trapped air to be bled out. As with most things bike, it is about good maintenance!I have Code RSC on both my bikes................loads of modulation and power and no issues in over 2 years of UK use on the older bike.

 

[tjl5709]

I am amazed at how well this worked.

 

[Jorva 1983]

I am amazed at how well this worked.

Same here. Sram needs to have a look at this. Makes a world of difference when the pistons in the calipers can move like they shoud

 

[Mikerb]

Same here. Sram needs to have a look at this. Makes a world of difference when the pistons in the calipers can move like they shoud

A lot depends on the orientation of the calliper. I only have to clean/lube the front calipper a bout once a year because it is oriented virtually vertical and is behind the fork leg so in a sheltered position. The rear calliper on both my bikes is horizontal and regularly gets covered in trail mud/dust etc. Mine are Code RSC brakes. In the winter I clean/lube the rear calliper pistons a bout once a month. I find the brakes super powerful and with lots of modulation.............never understood why folk ditch them for Hope/Magura etc at huge cost when all that is required to keep them working great is a little maintenance.

 

[CruJones]

I find that the Code brake pistons default to a distance from the rotor that’s too far for my liking. You can clean them and reset the pistons, but they will default after a long ride to a distance that is too far. I really want to swap to Magura, but dislike that they don’t sell any replacement parts for their levers or calipers.

 

[Mikerb]

I find that the Code brake pistons default to a distance from the rotor that’s too far for my liking. You can clean them and reset the pistons, but they will default after a long ride to a distance that is too far. I really want to swap to Magura, but dislike that they don’t sell any replacement parts for their levers or calipers.

In any sealed system the piston can only retract the same distance as it is pushed out..........unless there is a leak in the system or they need bleeding.

 

[CruJones]

In any sealed system the piston can only retract the same distance as it is pushed out..........unless there is a leak in the system or they need bleeding.

That's true, but the interface/tolerances of the seals and pistons (among other things) determines how much the pistons retract from the rotor. What I find is that SRAM's sit a bit farther than Magura's by default and hence why SRAMs always have a farther lever travel before the pad contacts the rotor vs Maguras. My preference is a small gap between the pads and rotors, but I really dislike Magura's lack of serviceability.

 

[IOUZIP]

My 2022 Levo Expert with Code brakes and calipers had 1 of the 4 pistons stick on the front. I spent an hour trying to get it to work again. Braking with 3 pistons was causing wear more on one side of the pad. Considered taking it in under warranty for 1 week diag then 1 week wait for part and install. In the end I still have SRAM Code brakes. So what to do...

I will pull the SRAM brakes to resell and install Hope T4 V4 and the heavy duty rotors this week.

 

[James_C]

would suggest taking the caliper apart and freeing up the piston. Although you have the challenge of how to get it out without damaging it.

 

[IOUZIP]

I already freed the stuck piston. Pumped the lever while 3 pistons were held back. Added slick honey to the pistons and all good now. Have already switched to the Hope brakes this week.