Tuesday, January 31, 2012

Corrosion Breaks Things

broken bolt

In my last post, I mentioned I was changing the Urals tires, but it didn’t go very smoothly. One of the mounting bolts for the front caliper got stuck about a 1/3 of the way out.

As I was removing the bolt with my trusty wrench it started to get looser and then tighter. I stopped. I didn’t want another broken bolt. The last one took way to long to fix, but since that adventure I have lots of tools to remove broken fasteners.

I tried to tighten it and it got tight that way too. I reached for the impact gun instead. It just sat there hammering away for a minute and then “whirrrrrrrr….” The gun spun like it had removed the bolt. I was relieved until I moved and saw a shorter bolt fall out of the socket with a little nub still sticking out of the caliper.


(this is actually close to what I said, but I’ll let you use your imagination.)

Time for a break. hah!

I asked my wife for a ride to the hardware store since it was a bit snowy for the scooter. I bought some new stainless steel bolts to replace the regular one. I bought two M10x35x1.25 for the caliper mounts along with new washers. I also picked up two new M10x45x1 bolts along with associated nuts and washers for the front and rear axle pinch bolts. Might as well replace them since I had them off and I was already at the store.

New and Old below:

New Stainless Axle Pinch Bolts

Now, back to that caliper. I tried using my bolt extractor tools while the caliper was still connected to the bike. It quickly became clear it wasn’t going to be easy, so I removed it from the bike. I needed to change the brake fluid anyways.

Gun-shy from my last stuck bolt in a caliper, I asked for help before I made things worse with my inexperience removing stuck fasteners.

My step-dad to the rescue. He has many years of experience working with stuck metal. His hobby is restoring antique tractors. He frequently has to find ways to fix or make parts since they can not be purchased.

Since the caliper is aluminum, we just used a little bit of heat to try and expand the threads. Used improperly, this torch could melt the entire caliper! I did the smart thing, and just took pictures. Leave that to the experts.

a litle heat

The little nub still wasn’t going anywhere, so we ground it off. It was pretty deformed by this point.

a little grinding

Then we carefully drilled out the center of the bolt all the way through. We got lucky that the hole for the bolt goes through the caliper.

a little drilling

Then we took turns carefully filling by hand with a rat tail file until the bolt was paper thin. It was a persistent beast and didn’t want to come out. We carefully tapped it with a finely ground center punch pulling at the edges. It started to collapse and come out.

broken bolt

The threads were a bit messy afterwards, so we cleaned them up. I was amazed when I could thread the new bolt in by hand all the way to stop. We spent two hours start to finish removing the bolt, and it saved me ordering a new caliper from WA (or maybe Russia). I’m very grateful for the experienced assistance. I couldn’t have done it myself.

Ural Front Caliper

With the caliper fixed, I went back to mounting the tires, so I could put them back on the bike and bleed the brake. The adventure isn’t over yet…


  1. Did you use some blue anti-sieze on the new bolts to prevent galling? Important when using stainless screws into aluminum or pot metal.

    1. no... doh. a quick look online about SS/aluminum and galling shows me I should add something. thanks!

  2. Broken bolts and fasteners, they're quite the headache and your FIL sounds like a handy guy to have around! The heat method has almost never worked for me, probably doing it wrong.

    I too have extractors, impact drivers....but luck is a major factor it seems. On my Ural, I ended up replacing at least half the fasteners with good stainless steel ones....


    Redleg's Rides

    Colorado Motorcycle Travel Examiner

    1. heat never worked for me either. I was both doing it wrong and not enough. I was recently corrected to heat the surrounding area rather than the bolt. heat makes the area get slightly bigger. I was also using too small of a torch to head the metal enough for expansion. I'm lucky to know people who have more experience in this area.

      I've replaced a few preemptively with stainless. too much money to replace them all right now.

  3. Chris:

    I'm glad I know nothing about extracting broken bolts. I have to leave it to the experts. Good thing you had "help". I wonder why the hardware isn't stainless from the factory

    Riding the Wet Coast

    1. money. stainless costs more than regular steel. I'm learning. :) I'm very happy I had help.