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jersey87

Stuck dog bone bolt...new frame or go ride?

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With the lockdown here I thought it a perfect time to take the back end off the Evo and check and regrease all the bearings, linkages, ect.

(I'll get the limp excuse in now - this is my first trials bike and the first time I've taken it apart to this extent...and initially I was just changing the fork seals but go carried away!)

 

It was the putting it all back together that I cocked up:

When refitting the dog bones I didn't realise the 'special bolt' had sheared it's head as I was tightening it until it was quite far into the frame...

s-l640.jpg.6fb0994604e149fc15f654c4b5257734.jpg

Not sure it's a Beta specific quirk but the positioning of the front dog bone mounts are not very accessible from the sides so I have no way of setting a drift (or such) against the opposite end and tapping the bolt back out - which means, as much as I've tried tapping (sworn at) it the thing wouldn't go back out.

Can see how far in the head is here compared to the left hand one.

IMG-0718.thumb.jpg.228ed0d103768068b7bc60771c3dc3f2.jpg

 

As it was well and truly in there I decided it would at least hold the dog bone in place and serve it's purpose.

It was when I went to refit the swing arm that I realised the bushes in the ends of the dog bones have different internal diameters (front and rear) due to different size bolts.....and of course one of the larger rear bushes was in the stuck front end of that dog bone!

So lifting the swing arm now highlights the couple of mm movement on that link (not easy so see in photos):

IMG-0719.thumb.jpg.45699bb5a7e48b8e516dd7f9f3a3f083.jpg

IMG-0720.thumb.jpg.24d764ad42b8f5f2af9e1d4c870682b7.jpg

 

So....is the frame going to split in half and I'm going to have to bring my bike back to my van in a wheelbarrow from the first section of (whenever) the next trial is....or do I just ride and keep an eye on it?

 

Cheers for reading

Dan

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Can you get the shock out of the way, then remove the swinging arm and use a bit of studding with one of those long nuts to push the bolt outwards ( pushing against the head of the bolt on the other side), then as it gets close to the back of the footrest hangar cut it, then push again and cut again if needed?

Edited by misscrabstick
stupidity

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Those things shear very easily.  I wonder what percentage of people shear one the first time servicing Evo dog bones.  I bet they sell la lot of them.

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Take the swinging arm and shock off and get a angle grinder with a 1mm disc and run it through cutting the bolt leftovers so you can remove the dog bone 

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14 hours ago, misscrabstick said:

Can you get the shock out of the way, then remove the swinging arm and use a bit of studding with one of those long nuts to push the bolt outwards ( pushing against the head of the bolt on the other side), then as it gets close to the back of the footrest hangar cut it, then push again and cut again if needed?

Keep pulling/pushing it through in the direction it's already gone?

I could continue to tighten the nut - which is what I was doing until I realised it should have stopped by now. Doh!

 

The sheared head end is wider than the mount hole in the frame which is what it's stuck in so was thinking if I kept moving it through it'll just get stuck in the dog bone bush (the short 'correct' one) and then the mount on the other side.

Perhaps worth a shot though if I can cut it down...

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Can you get a clamp of some sort in there.  Maybe a small version of this.  one side on the bolt threaded area the other side on the frame next to the bolt hole.  

Push the bolt back toward the shock, eventually having enough bolt shank showing to grab with pliers.  this is of course assuming  you can get the nut off or cut off the nut.

IRWIN VISE-GRIP Welding Pliers, Fast Release, C-Clamp Locking, 6 ...

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15 minutes ago, zippy said:

Can you get a clamp of some sort in there.  Maybe a small version of this.  one side on the bolt threaded area the other side on the frame next to the bolt hole.  

Push the bolt back toward the shock, eventually having enough bolt shank showing to grab with pliers.  this is of course assuming  you can get the nut off or cut off the nut.

IRWIN VISE-GRIP Welding Pliers, Fast Release, C-Clamp Locking, 6 ...

Thanks for the suggestion but unfortunately there's not much room at the side the tread is on (about 4cm) - difficult to fit a clamp when I tried that.

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Just had a look at mine to gauge the amount of space. I wonder if you could pack out and protect the inside of the frame with some hardwood or aluminium and then use a steel wedge (a bit like the ones used to release a drill from a morse taper sleeve) to drive the bolt back through the way it came. You could work from below, tapping the wedge upwards and when (if!) the bolt moves a little, add a spacer and repeat - it may free up once the broken end clears the bush.

 

Edited by markparrish
added phrase
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On 5/30/2020 at 9:14 AM, jersey87 said:

Keep pulling/pushing it through in the direction it's already gone?

I could continue to tighten the nut - which is what I was doing until I realised it should have stopped by now. Doh!

 

The sheared head end is wider than the mount hole in the frame which is what it's stuck in so was thinking if I kept moving it through it'll just get stuck in the dog bone bush (the short 'correct' one) and then the mount on the other side.

Perhaps worth a shot though if I can cut it down...

I think if it's pulled through the first frame hole it'll keep going with sufficient force?

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Did you get this sorted? If so how?

I've been there, done that - new bike (5 hours), discovered bolt head was off and jammed as you describe. Pulling it through enlarges the frame lug hole.

From memory I used a small clamp to get onto the threaded end and push it back out. I then welded a new head on in it while I waited for a replacement, but found that the welded section got brittle and snapped off easily. Now I am very careful to torque correctly - can't get a torque wrench on that nut so I put the ring spanner on the torque wrench in a vice and calibrate my finger before tightening - for me it's a very firm one finger pull = 40Nm.

One of the very few really badly designed parts I've come across on the Beta. 8mm stud with a head welded on - who came up with that idea, there's room there for a better solution!

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Jitsie do a replacement screw with more meat on the top of the bolt so should be stronger.

 

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