Advice on stuck/stripped bolts, and bleed screws

I finally got a chance yesterday afternoon to start installing stainless steel brake lines on my 2002 R1150RT (https://forums.bmwmoa.org/showthread.php?100463-R1150RT-Stainless-Lines).

Two steps forward, one back, it seems. I am more than a little frustrated with myself at this point.

Issues I ran into that I am looking for advice on, in approximate order of lower to higher difficulty to solve:


Bleed Screw

- The left front caliper didn't want to bleed at all (right one went fine) I pulled the bleed screw and I guess it's just clogged. I can see what looks like a tiny hole in it, but I couldn't get any fluid through it at all. I happened to have an old bleed screw from my old Yamaha kicking around, which I swapped in, but I'd like to get the "proper" part. In looking at:
https://shop.maxbmw.com/fiche/DiagramsMain.aspx?rnd=771786&vid=51764

...I see it is part 7 on this image:
https://shop.maxbmw.com/fiche/DiagramsMid/B0004041.png?v=09082020

... but they don't note a BMW part number for this. Should I just go get a "standard" bleed screw?


Rear Caliper Bolts

After finishing up the front lines, which bleed screw aside went okay, I started up on the rear. Well, I can't seem to budge the bolts holding the caliper to the frame.

I've gone at it with my impact wrench (just an cordless electric, not super burly), and have done my best to get leverage on it. But no movement.

I squirted some PB Blaster on there, and tried again this morning, but nary a budge. I don't want to strip these bolts out (eek, see next item), so am trying to be careful.

My next thing to try is to get a heat gun on there for a long time, to see if that helps, and then maybe after that a torch.

Any other suggestions? Neither of the bolts on the rear caliper seem to want to budge.


Stripped Retaining Pin

While putting the front left caliper back together, when I screwed in the retaining pin (I was using a pretty tiny ratchet wrench), I felt like I over-tightened it (no, I didn't use a torque wrench, alas). Well, I tried to immediately back it out, and managed to strip the torx bolt in the process. I tried putting the impact driver on and just made a mess of metal shreds.

So the caliper is back together, but if I ever want to get those brake pads replaced, or take the caliper off again, I'll need to solve this one.

From https://shop.maxbmw.com/fiche/DiagramsMid/B0004041.png?v=09082020 it looks like this is part of part 11:

34 11 7 660 850 SET: MOUNTING PARTS SET 0.05 1 $30.54

Which I guess I'll order, but if anyone has a way to get just the retaining pin, instead of the whole kit, please advise.

Then the main thing I need to do is figure out how to extract the stuck/stripped pin.

I'm looking at bolt/screw extractors on Amazon now. Any tips/recommendations?

thank you!

Bleed screws:

I believe the bleed screws on your front calipers are available from Brembo. I've seen the Brembo part on Ebay new for around $14 a screw; their thread pitch, if yours are the same as on my R850R, is M10 by 1.0mm. I tried a set of aftermarket ones from my local auto parts store that were the right thread pitch, but they were about twice as long as they needed to be.

Stuck caliper mounting bolts:

Per Project Farm's independent testing, Liquid Wrench makes the best penetrating oil. https://www.youtube.com/watch?v=xUEob2oAKVs

But your idea of using heat is the very best way to break rust. What you want to heat is the part that the bolts thread into, not the bolts themselves. You can also go one step further and get some "freeze spray" or a can of what's usually sold as "computer duster" from a big box store or an office supply store; these are really just pressurized CO2, and if you turn the can upside down you can spray a whole lot of cold into the hex socket of the bolt while also heating the part it bolts into. Enough expansion of the threaded hole and contraction of the bolt can literally break the rust bond between them because of the different thermal expansion coefficients of steel and aluminum.
If those combined don't work you will likely have to resort to destructive measures, or paying someone else like a machine shop to drill it out and re-thread the hole with a Time-Sert.

Stuck brake pad retaining pin:

You should send us a picture of how the head of that pin looks. Can any part of its shaft be access from between the brake pads? Does it screw into a blind hole, or is the bottom of the threaded portion visible on the other side of the caliper? Those would both be good avenues for attempting extraction from somewhere other than the head.

Also per Project Farm testing, Grabit Pro makes the best screw extractors if you have to go that route. https://www.youtube.com/watch?v=XVTn6wI4g6s

FWIW, I have found that most any oil contacting the rubber used in brake systems has a wild adverse effect on the rubber. No big deal if a complete rebuild with new seals is the next part of the repair.
OM

Since you have to replace anyway, I'd upgrade to speed bleeders; they're not expensive. They make fluid change much easier. I have one on my clutch as well. Here's where, I think, I got mine; http://www.speedbleeder.com/

Thanks all.

I have ordered speed bleeders, and some bolt extraction kits based on the feedback above!

When I next have the opportunity, I'm going to start by applying heat to the frame (and cold to the bolt), to try and unstick those caliper bolts.

Issue is not rust. It is galling. Steel bolt and aluminum brake caliper. Always use some antisieze for the next guy. I would just get a better impact and let it rip.

tsconver said:

Issue is not rust. It is galling. Steel bolt and aluminum brake caliper. Always use some antisieze for the next guy. I would just get a better impact and let it rip.

Click to expand...

Assuming it's galling and not rust (and I tend to agree; I don't really see any rust most anywhere on this bike), would heat/cold application not help?

Maybe I'll go try to get some better Torx bits, too, and get it on a bigger wrench.

htomsett said:

Stuck brake pad retaining pin:

You should send us a picture of how the head of that pin looks. Can any part of its shaft be access from between the brake pads? Does it screw into a blind hole, or is the bottom of the threaded portion visible on the other side of the caliper? Those would both be good avenues for attempting extraction from somewhere other than the head.

Click to expand...

I took a couple of pics last night:





Yeah, I think I ought to be able to get purchase on the shaft with a vice grip, perhaps. I've also got a Grab-it kit coming, too. Before I perform any surgery, I'll need to order a new bolt. Stopped at my independent shop last night; none on hand and he wasn't enthused to order, so am going to go and look for some online.

As for my stuck rear caliper bolts, I discovered I can access the rear of the bolt hole THOUGH the holes in the rear brake disc. I put some PB Blaster on there (but yeah, no rust really so I'm guessing galling/overtightened). I've got some Kroil I'll attempt with too.

I did try heating the caliper up with a heat gun, and then shot cold CO2 onto the bolt itself. No help. I'm concerned I'm going to strip out THAT torx bolt head - the bit has more play in the bolt head than I would like.

You have a welder? I would drill it our round and slip a bolt in it that is the same diameter. Place a washer against the caliper itself to protect it then weld the bolt tot he stripped head. Then use an impact on it. Usually the heat from welding will help break it loose. Fortunately that one would not be hard to drill completely out.

Other option is to pull the caliper. Use a Dremel to cut the bolt head off and then split the caliper and use vice grips or weld a nut to the remaining bolt and spin it out.

Could also try driving the next size up torx into it.

tsconver said:

You have a welder? I would drill it our round and slip a bolt in it that is the same diameter. Place a washer against the caliper itself to protect it then weld the bolt tot he stripped head. Then use an impact on it. Usually the heat from welding will help break it loose. Fortunately that one would not be hard to drill completely out.

Other option is to pull the caliper. Use a Dremel to cut the bolt head off and then split the caliper and use vice grips or weld a nut to the remaining bolt and spin it out.

Could also try driving the next size up torx into it.

Click to expand...

Screw extractor!!!!

Looks like a cold chisel could be held in a pair of vice-grips and fit into the hole as best it can…… Then while applying a twisting motion……. Hammer on the cold chisel..
This procedure is almost like using an impact driver.
OM

I just had a Time Sert fix done on a stripped bolt on my stator cover done yesterday. It was only a stripped hole so a little more simple than your issue.

Could you cut slots into the front fence and try to drift it with an impact driver?

Welp, on Friday I put some Kroil in the stick caliper bolts - turns out I can access the back of it through the holes in the brake rotor... then proceeded to strip out one of the bolts. Ack!

Life is crazy busy so haven't had a chance to get back to it yet... but thinking next step is to take off the rear wheel to get better access. And maybe I should just drill out the bolts from the back?

I'm guessing I need to find some crazy carbide/diamond drill bit to get through these bolts. Although they're bloody soft enough to strip out, so who knows.

Someday I'll get to ride again....

That bolt may be softer than you think if you could strip out the drive end. Maybe it wasn't heat treated to spec?

Try with a quality small diameter regular sharp drill bit and use cutting fluid. Then go with the full minor diameter drill bit.

nrpetersen said:

Try with a quality small diameter regular sharp drill bit and use cutting fluid. Then go with the full minor diameter drill bit.

Click to expand...

Just ordered new bolts, being optimistic I can drill these out.

https://www.trfastenings.com/products/knowledgebase/thread-geometry/metric-coarse-standard

Looks like the minor diameter is 8.160mm - 8.376 (male to female) for an M10. I'm thinking an 8mm drill bit, you think? I guess if that much material is drilled out, I ought to be able to get the bolt out at that point. Or try to find an 8.25mm?

You may want to purchase a left hand drill bit…..while you a’ byin’.
OM

Omega Man said:

You may want to purchase a left hand drill bit…..while you a’ byin’.
OM

Click to expand...

I was thinking that.... but since I'll be drilling from the backside (I hope), I think I want a regular bit.

Just ordered a set of these:
https://www.amazon.com/gp/product/B07MZQMPMC/ref=ppx_od_dt_b_asin_title_s00?ie=UTF8&psc=1

As usual for me, two steps forward, one step back.

I was able to get the bolts out of the caliper, yay!

Root cause? I'm an idiot... I was using a one-size-too-small driver.

The one I stripped I was still able to pound it in and then get it extracted.

Thanks for all your help!

To put a pin on this thread:

- The replacement bolts, and replacement caliper pin arrived.

- The bolts I replaced, though they're okay with the correct torx bit (!) - I kept the old ones. I also put Never-Seize on them.

- For the caliper pin that was stuck, I was able to drill it out a bit, and then pound in the next-size-up torx bit, and then was able to extract. I also put the new one in with some Never-Seize.

thanks all!