How to Use the DT-5.2 Disc Brake Mount Facing Set

How to Use the DT-5.2 Disc Brake Mount Facing Set


Hi, I’m Max with Park Tool, and today we’re going to be running through the instructions on how to use a DT-5.2 Disc Brake Mount Facing Set. The DT-5.2 works on IS mounts, Post Mounts, and Flat Mounts It works in frames with widths from
135 to over 200 millimeters and in forks with widths from
100 to over 150 millimeters and it also works on axle sizes
from 12 millimeters to 20 millimeters. In this video, we’re going to set up and face a Post Mount system. We’ll also show the setup procedure for an IS Mount system, a rear flat mount system, and a front flat mount system. And before we begin, remember to always
wear safety glasses and always use cutting fluid. Let’s get started. In our first example, we’ll be facing a post mount adapter on a 12mm thru axle rear end. For this, we will need our post mount cutter and our adapter to adapt the axle
as well as the 12mm thru axle adapter. When you assemble these parts together, it is very important to note the orientation of the slider and the arm: the slider needs to be above the
arm with the sliding going down. So, bring these together – and now we can mount it onto the frame. First step in putting it on the frame is to remove the thru axle and then insert the thru axle and body together into the frame. Just get this thru axle engaged so that everything hangs. Set the width by sliding out the telescoping inner piece
and then set that with using this 5mm bolt. Then tighten the axle into the frame and put pressure onto the entire assembly to keep it snug. Now that we’ve got the axle in the frame,
we can set the parallelism. In order to do that, simply bring these wings into contact with the post mounts. First, tighten the bolt between the cutting arm and the slider and then tighten the bolt on the body
between the body and the axle. Now you have established your parallelism and
you’re ready to make your first cut. Transition to one of the mounts again Again, tighten the slider bolt in place, install the knob Always important to use cutting fluid whenever you’re cutting – helps keep the tool life longer and with light hand pressure you can make your cut and you will turn until you see a consistent ring all the way around – we’re not quite there yet. Getting close, but not quite. Onto that consistent range of silver
all around that mount, so we’ll cut just a little bit further. Always important to
keep adding cutting fluid So at this point we’ve cut quite a bit of surface off. We’ve got a small low spot here, but it’s not
going to impact our mounting surface So we’re going to move on to setting our stop collar height that establishes our baseline level for the cut so we bring this caller up and tighten it into place
and that needs to be in contact with the slider so the slider body will be in contact with this when this cutter is in this hole. Now we have a baseline, we can transition to the other stop. So we bring that over here, tighten this bolt again, we can see that we now have a small gap between our slider and our stop collar which means we’ve got room to cut on this post so add a little bit more cutting fluid and start to cut. Now we’re going to continue cutting until
we see this gap go away – we’ve got a ways to go but we’re getting there. so now we have bottomed out
our slider on this stop collar. We are in a position where one of two
things could be possible: either we are done facing and we have a complete ring, or we need to continue facing and then come back and reface the upper post So in this case we still have black here, so that means we need to continue facing. If this were silver all the way around,
we would be done at this point but since it is not, we will continue facing. We will drop our stop collar and continue to face until we have that clean silver ring all the way around. Check this surface – it looks like we have a nice clean surface now so we’ll set this cutter back down make sure it’s clean, set this cutter back down
and re-establish our baseline height. Now we can transition back to the top post We can see we have a small gap again as expected and we will continue to face this until that gap goes away. We can see that our gap is now gone.
We’ve stopped cutting and our facing is complete. In this case, we have open dropouts
coupled with an IS Mount so we will need our IS arm, as well as the slider and
stop that we used previously, and for the open dropouts we need our open dropout axle. In assembling these parts, it’s important to know that the slider is oriented to the cutter like so. The stop collar goes underneath the slider, slide everything over this axle, and you’re ready to install it into the frame. The first step in installing it into the frame obviously is fitting it into the dropouts. In this case you’ll need to telescope the axle out, slide it into the dropouts, snug both ends and then tighten securely into the drop out
before tightening this stop collar. Now that everything is tight, your parallelism is automatically achieved because you are on the axle, and all the steps for facing are the same
as with the Post Mount from here on out and you’re ready to face. In this case, we have a flat mount disc brake with a thru axle rear end. The DT-5.2 comes with some additional
parts to allow you to face Flat Mounts. It comes with a set of standoffs for the rear as well as a set of standoffs for the front and a replacement bolt for the front – we’ll get to those later. In the rear, you use two standoffs – they go into the frame, one in each slot. They have an O-ring that allows
them to keep their place once inserted. The setup for a Flat Mount uses the same
parts as a post mount, but oriented slightly differently. Use the post mount cutter as well as the post mount body, but for the slider, instead of having the
slider like so, you flip the slider like so. Slide it all together Select our thru axle rear axle and we are
ready to insert it into the frame. Again, you slide the thru axle adapter in, put it into the frame, slide your thru axle through the entire part lightly start it, then set your spacing. Tighten the clamp here and then snug your axle. Now you’re ready to establish parallelism – bring the cutter body and set it onto the studs then you tighten the bolt between the cutter arm and the slider and then finally you tighten the body onto the axle. Now the last step: pull these studs out to reveal the mounting surfaces themselves and you’re ready to face. The procedure for facing is the same as demonstrated earlier on the Post Mount system. In this case we have a flat mount front on a 12mm thru axle fork so we need some unique parts we haven’t seen before: we’ve got these additional parts that
adapt the Flat Mount to the Post Mount. The parts you’ll need from this kit are your Post Mount adapter, your 12mm thru axle front, which is this sleeve in addition to the 15mm, and the body there so just like with the other flat mount, you need to make sure that your slider goes on like this so we’ll get that set up and additionally, you’ll need to change out
this silver bolt in place of this black bolt. To do that, simply take your knob, set it on there,
hold the knob firm, insert a 4mm, The bolt will back out, insert your new bolt and you’ve converted now to be able to
face the front of a Flat Mount. Take these two standoffs, install them into
your fork these standoffs are threaded, so they thread into the holes on a Flat Mount fork – get them nice and snug. Bring over the rest of your parts, again install the adapter into the body, pull your axle out install into the frame start the axle snug that width and then tighten the axle now we proceed with parallelism – exactly similar to the rear Flat Mount where you locate on the studs and tighten the slider and tighten the slider and then finally
tighten the body and now remove the studs and you’re ready to face. the procedure for facing is the same as demonstrated earlier on the Post Mount system. That was the basic procedure on how to use the DT-5.2.
Thanks for watching.

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19 Replies to “How to Use the DT-5.2 Disc Brake Mount Facing Set”

  1. Looks like an awesome tool, very clever. I am reluctant to buy one though since there is no caliper facing tool. Those can be just as off.

  2. so the stand offs that are used to set parallelism on the flatmount are set onto the possibly crooked flatmount? wouldn't that make the final faced surface parallel to the un-faced surface that might have been crooked?

  3. Did the non drive side drop on QR before tightening or am I just seeing things? Would skew entire process. Heavy powder coat or paint in the drops has to have an effect on the accuracy of this device. Picky, picky, picky, I know, but then that's why you would purchase this for the shop anywho. Minute 6:47ish

  4. It's absurd to even need this tool with the price of 'high-end' bikes and components. These parts should come squared and machined out of the box.

  5. I would never do this myself as most of my efforts to work on my bikes generate as many new problems as they fix. Still I find these videos fascinating.

  6. How would you know if you even needed this done? Don't the caliper mount bolts have a beveled washer to allow for adjustment?

  7. I use BB7’s, they have a system to avoid this kind of tinkering later on, loosen the mounting bolts, squeeze brake lever, tighten bolts, done.

  8. Is this more problem more common on flat mounts compared to IS? Also, I dont need to comment about the slopiness of frame manufacturing

  9. You must have to use some shims between the caliper and the shaved post mount if you have shaved off as much as you did in this video? Other wise, the caliper will set too low and the rotor will drag on the caliper body. Just curious if you did another video after this one about that?

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