How To Bleed SRAM HRD Disc Brakes | Road Bike Maintenance

How To Bleed SRAM HRD Disc Brakes | Road Bike Maintenance


– Now the reason for
bleeding disc brakes is that sometimes your hydraulic brake
lines can actually become contaminated with dirt, air,
or in some cases even water. Obviously that results in
poor braking performance. So today we’re gonna look at how to bleed the SRAM hydraulic road disc brake system. So you can get stopping better again. (jazz music) So what you are gonna need is a bleed kit. So in this case I’ve actually
got a SRAM professional bleed kit. Inside of her I’ve got the
DOT fluid oil, I’ve got the syringes, hose attachments,
all of the necessary things as well to space
out the calliper and make sure we do the right job. Also you’re gonna need a
workshop towel or a lint-free cloth, some nitrile gloves,
isopropanol alcohol, and also a toe strap, or
failing that an elastic band that will come in very handy later on. So today I’m gonna be
bleeding the front disc brake. So first of all I’m gonna
remove the front wheel. And then remove the little
clip that’s on the pin there. And then with a two-and-a-half
mil hex wrench, remove that pin and then remove the pads. And then, gonna put in there
a little bleeding block. Now that block that I’m gonna
put in there is actually really useful because it
actually stops the pistons from moving and potentially
popping out if you touch the lever. So make sure you put
that in there, keep safe. So this is where you really
do need those nitrile gloves. First up, we’re actually gonna screw the bleed clamp assembly into the syringe. And then, gonna fill it half
full or as close to half full as you can get with the DOT fluid. So, keep a good eye on that. And then, when it’s about full, stop. And now, gonna hold that
syringe up this way. With a shop towel just
basically what we wanna do is get rid of this air,
so, gently force that up using the towel to catch
any residue and remove those air bubbles. So you are gonna have a
little bit of fluid come out. Maybe give the syringe a couple of taps just to release any more air. Give those clamps a good wipe down. And then lock the hose in position so it’s like that. So the next step is actually
to remove as many pockets of air that are in this
DOT fluid as possible. Now if you look at it,
doesn’t look like there’s any air in there, but there is. Does get trapped in. So how we gonna do it? Well, make sure that that
clamp is still locked down and then gently pull the plunger. And as you can see, look at that. Look at all those bubbles that are rising. And then gently let it back. And repeat this process quite a few times. We wanna get as many of those
bubbles out as possible. You may wanna hold it and
just flick it a few times, just to get rid of them. Try and get rid of as many of
those air bubbles as possible. It’s gonna help in the long run. So just be very patient with it. Just keep repeating. Then, with the other syringe,
you’re gonna do exactly the same but fill it just quarter full. And then we move on to the next step. (jazz music) A quick check to do is actually
to measure that the blade of the lever is not more
than 90 millimetres away from an imaginary line using the
brake lever hood as a guide. If it is, then the bleeding
procedure is just not gonna work properly, and you’re not gonna get effective braking. So if that lever’s more
than 90 mil, then just put a two-and-a-half millimetre
Allen key in there and just turn it and just bring that lever inwards. And then remeasure. Make sure it’s under 90 mil. (jazz music) So now with a corresponding
brake lever, peel back the lever hood and then undo
that bleed port screw. Keep it somewhere safe. And if there’s any excess
oil at all, or DOT fluid, just wipe that away,
keep it nice and clean. Then, gonna wanna thread the
quarter full syringe into that key port. So next, we’re gonna remove
the little bleed port screw of the calliper, and with
the bleed kit we actually get a little T10 key, so
you’re just gonna want to remove that. And then, just wipe away any excess that may have popped out. And now we do a half full syringe. Simply screw that into the
bleed port of the calliper. It’s important you get
them the right way around, so it’s the half full one in there. (jazz music) So now we’re gonna
release those hose clamps and then gently on the
calliper syringe, push that in so that the lever syringe
goes to about half full. Now, you will see a few
air bubbles probably pop up into there, don’t worry about that. But just make sure it doesn’t
go any more than half full and then just lock down
that clamp on the lever. So using your toe strap
or elastic band, just hold the lever blade in up
against the handlebar there, make sure it’s nice and
snug and doesn’t move. So now you’re gonna wanna
hold the syringe vertically like so, and then gently pull
out, which as you can see there’s some air there
coming out of the calliper, that’s exactly what we wanna be doing. Removing all of that air. And when the bubbles have
finally stopped rising, you gently push it back down in. Just repeat that process a few times. Just to make sure that we’re
getting all of the air out. As you can see there’s
some more air coming out of the calliper. So now what we’re gonna need
to do is actually remove the elastic band from where
it’s holding the lever in place. But at the same time keep the
lever in place with our hand. And then, you’re gonna wanna
gently push the calliper syringe inwards and at the
same time just allow the lever just give it a little bit of
resistance with your hand, just allow it to return
to its normal position. So once the lever’s returned
to its normal position, simply clamp that hose
and unscrew the clamp from the calliper and then
refit the bleed port screw. It’s to one and a half
Newton metres, now that’s not a lot, and it’s very fragile
down there, so don’t be tempted to torque it up
loads, otherwise gonna end up stripping the thread. Okay, so now we’re going to
release the clamp on the hose and then simply pull and
release a few times just to remove any bubbles from the
reservoir here in the lever. Then you’re gonna wanna
squeeze the brake lever into the handlebar and out about 10 times and then repeat the process
again, pushing and pulling trying to remove any air
from the cylinder up here. Just repeat that process
two or three times. Just wanna get all of the
air out of the system. So now that you’ve got all of
the bubbles out of the system just apply a small amount of pressure. Just back into the lever
that way no air’s gonna get back into the system. And then close off that clamp on the hose. And then unscrew it. And then refit the bleed port
screw on the top of the lever. Now with your isopropanol
alcohol, simply put some onto a cloth and then give, just clean so make sure that there’s
none of that laying around. Because it’s not particularly
good for any rubber or handlebar type. And then you can do the same
thing as well, just down there on the calliper, make sure there’s none of that hanging around. (jazz music) So now, just remove that bleed
block and then refit the pads and your wheel, and give
the brakes just a couple of little tugs and make sure
that there’s no leaks at all from any of the seals. There won’t be though, if you’ve followed my instructions carefully. Right, well I hope that your disc brakes are now working perfectly. Let me know in the comments
down below how you got on. Keen to read them as ever. Also remember to like and share
this video with your friends and if your disc brakes
don’t need bleeding but just a little bit of TLC, click just down here to find out how.