Fork leg pinch bolt removal?

[NJD]

Afternoon.

So I've got a pair of fork legs that were removed due to being faulty (not rebounding/sticking) and I've decided I want to open them up and look inside to kill some time.

The cap on the top loosens but I can't seem to snap the fork leg pinch bolt. It's 6 mm and the highest size I can see is 3/8; would it just be a case of getting a 6 mm 3/8 hex bit and attaching it to my cheap 3/8 ratchet and going with an instant snap (I realise if you attempt to slow turn the bolt the leg will just twist)?

Alternatively I was going to go with a 3/8 breaker bar, and maybe an extension bar depending on the length of hex key (something I'd look at in person).

I'm going to guess that 3/8 is needed because I can't seem to remove it with my 1/4 drive (I've no idea of the torque setting on these things).

Just a mini project for fun, and a learning curve.

Thanks in advance.
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The do it all, T̶h̶e̶ ̶b̶r̶o̶k̶e̶n̶ ̶o̶n̶e̶,̶ ̶T̶h̶e̶ ̶b̶i̶g̶ ̶l̶u̶m̶p̶,̶ ̶C̶h̶o̶n̶g̶ ̶N̶o̶o̶d̶l̶e̶

[Snod Blatter]

I'm finding your post difficult to understand but are you talking about the allen bolt that holds the damper rod in place? The one that you access through where the axle would normally be?

The more I read this, the more garbled it is. What do you think a fork leg is? The leg is the big aluminium bit, the stanchion is the smaller chromey bit..
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1994 CB250, 1984 CBX250RS-E, 1989 K100RS, 1995 TRX850, 2016 Z250SL

[NJD]

[ThatDippyTwat]

[Tankie]

heat locally with a gas torch, then spray with WD40,do this a couple of times, the idea is that the ali leg will expand a bit and the WD40 will then get in and lube the threads a bit.
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Always learning, everyday is a school day

[Tankie]

heat locally with a gas torch, then spray with WD40,do this a couple of times, the idea is that the ali leg will expand a bit and the WD40 will then get in and lube the threads a bit.
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Always learning, everyday is a school day

[Nobby the Bastard]

[bikenut]

Or leave the spring in and compress the fork somewhat then undo the bottom recessed damper rod allan bolt.

Next time, leave the fork in the yokes, then undo ( slacken not remove ) the recessed allan bolt. Remove fork from bike and do rest on bench.

You know of cmsnl for the exploded views.

Some damper rods have an internal hex........
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nuts about bikes

[NJD]

Right, i'm with you; so there's two methods: (1) hold the internals in place to slack the nut (2) compress the fork and snap it before removing the top part, and the spring.

Sorry, it's a fork leg of a chinky 125 so the best guide I had was a Haynes. I've looked at the workshop PDF for my current bike and understand it a little better now I know what the internals of a fork leg look like.

So a broom handle with a twisted edge, got it. What size hex bit should crack it, though? 1/4, 3/8 or 1/2. My Kwak PDF indicates an allen key can be used, which indicates to me that its more about getting the internals inside to stop moving than it is about outright power through a 1/2 drive.

edit: someone mailed and said using an impact driver may be easier.
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The do it all, T̶h̶e̶ ̶b̶r̶o̶k̶e̶n̶ ̶o̶n̶e̶,̶ ̶T̶h̶e̶ ̶b̶i̶g̶ ̶l̶u̶m̶p̶,̶ ̶C̶h̶o̶n̶g̶ ̶N̶o̶o̶d̶l̶e̶

[Teflon-Mike]

From the description, that I too found a tad garbled and hard to understand... it 'sounds' like you are trying to undo the damper rod bolt.

That bottom bolt goes through the fork slider, into the damper plunger. the plunger is free to rotate.... take note..... it is held in place by the fork spring, which in turn is held in tension by the stanchion cap..... the bit you say you have had no trouble to undo....

Put the thing back together exactly as it was to start, in the bike when (not) working.

When I strip a set of forks to replace the seals, I START by loosening the damper rod bolt, First, whilst the stanchion is still clamped in the fork yoke at the top....

If the forks are off the bike, I tend to use a 'scrap' fork yoke (as I usually have a few conveniently to hand!!!) to clamp the stanchion, and depending will hold it steady on the floor or in a vice or with a crow-bar..... That stops the stanchion twisting.

The fork cap stays 'on'.... the spring in situe, to put some load on the damper rod and 'hopefully' hold that still whilst I twist the damper bolt.

Untangle some garble.... I dont know of a bike that uses an imperial sized allen key.... the actual damper bolt tends to be either an M6 or M8 cap-head allen screw.... and as you have already discovered, its burried a heck of a long way into the recess of the fork leg, and can be a bit of a bugga to get at.

Some of this may be contentious to other mechanics who have their own preferences... b-u-t

1/ forget trying to use an allen socket.
To get them to engage the allen screw you need deep-reach allen sockets, and even then, the socket head can bottom on the fork leg recess before they actually engage or give much engagement.

2/ Use 'ordinary' allen key.
Using the reverse 'long' side of the key you should have the reach to get at the cap-screw... you just dont have the leverage on the short end to turn it too hard... this is NOT a bad thing. The damper rod bolt is not a high torque fastener, you shouldn't need a chuffin great breaker bar and bit of scaffold pole on the end to get enough torque to undo it.... if you try.... you will likely just frustrate yourself turning the damper plunger inside the spring, and or the stansion, making it even harder to stop twisting whilst you do nowt 'useful'.. yes a little extra leverage might be useful, but if it takes much more than a 1/2" spanner on the end of the allen key (or any other convenient size, you are popping the arm of allen through the ring end of spanner like a bottle opener to make it a hand-span longer, not trying to get engagement on the flats of the hex-bar, though if there is spare and you have a conveniently handy 6 or 8mm open ended spanner, that can work too)

IF the screw needs any more torque than that.... STOP.... before you break something!!!!

Some forks might have some other locking device in them, like a grub screw or circlip.... RTFM.... again, see what the experts say is the right way to undo this screw; look carefully at the scematics in the book, look for that missed locking tab, circlip or grub screw or whatever.....

If all good and it 'should' come undone, then if it dont, its likely corroded in the fork slider... screw usually steel, fork leg usually alloy, you get electrolytic corrosion twixt two, exacerbated by the screw being in a crud trap, under front wheel, where chit can get washed in, and is loath to get washed back out.....

First course is a good thread release like plus gas... NOT a frigging water dispersant like WD40, that is NOT, repeat NOT a frigging lubricant!!!

Second course... patience and perseverance, and a pokey thing, like an old clutch cable, conveniently frayed down to make a long thing brush, to get in and clean out as much crud as you can....

DO NOT USE A BALL HEAD ALLEN KEY!!!

Note the enphasis put on that statement. Ball head keys only engage the screw on a tiny tiny little flat of the ball, not the full depth of engagement... and they are designed to 'wobble' with the ball.... on a nice 'new' assembly they may be quick and convenient... on something a few years old and used, they are a very good way of chewing up allen screw heads..... take note!!!

This may require you go buy brand new a set of conveniently, usually pretty cheap, 'plain' allen keys.... but they 'work' and you have'em for next time, and other occassions where the convenience of a ball head is probably more of a hinderance than help.....

Also likely that if the job has ever been tackled before, that the allen screw has been pre-mullered by another numpty with a breaker bar and or ball-head allen!!!

Which leads to the last resort.... which is not nice, but is to drill the fugger out..... carefully... very very effin carefully!

Before that, IF the allen screw head IS butchjered, butchering it a bit more, wont make it any less srviceable, you 'may' try hammering in an oversize allen... another good reason for cheaper plan keys.... but a slightly oversize imperial allen key 'might' just hammer in and get purchase on the chewed cap, or you might be able to slightly grind one down, possibly with mild taper that will hammer in.....

BUT these are last ditch resorts.....

That screw SHOULD come out with PRETTY mild persuasion, and no enormous lever, or socket set accessories.....

It 'just' needs the back end holding still by being kept under pressure from the fork spring, and the fork stanchion held from rotrating, by little more than hand (or foot) pressure on a fork-yoke....

CLEAN the bolt, make sure that the cap is clear and you ARE actually holding and turning the screw, not just chewing it up, or twisting muck in the hole....

Seven times out of ten.... with the fork-spring holding damper rod, yoke clamping stanchion, and a 'good' plain allen key down the rebate, the cap cleaned well first, and no more than a hand spanner looped over the short arm of the allen, these things usually come out a treat..... any awkwardness or stubbornness encountered more often made by numpty mechanics... either NOT RTFM firstr, and or being brutal trying to apply gross force to TINY low torque fastener, with the wrong, and oft far too over-size tools, and doing the usual diving into the socket set loath to use plain simple and effective hand-tools....

Revisit, from the top.....
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[stinkwheel]

How I would remove them is to put my long-reach 1/2" drive hex key in my air impact wrench and depress the trigger for about 2 seconds.

However most people manage with a large allen key.

Another way I've seen it done is for someone to cut-down the L off an allen key (so you have a straight bit of hex bar) and use a socket on the other end of it.

They'll usualy come out ok if you haven't undone the top cap but as other have said, if the damper rod spins up, you need to jam it in place (or use an impact wrench).

Oh, once you've rounded it out with a cheap allen key and can't get it to grip any more, drilling the head off works well. The remaining stub invariably unscrews from the bottom of the damper rod with finger pressure. The bolts usually need to come from the manufacturer but tend to be inexpensive.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Riejufixing]

[Riejufixing]

[Tankie]

The only " pinch bolt" on a leg is the one that hold 's the axle ,If its not then it's a damper rod bolt...….Is that clear !
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Always learning, everyday is a school day

[NJD]

Recommendations where I can purchase the tool that will hold the damper rod in place (if there's one that will work across most forks, including my current bike, then I'd prefer to invest in that) so I can undo the damper rod bolt?

If the damper rod bolt can be undone with an allen key then my issue is that it's spinning, and is why I think taking the fork apart and holding the damper rod still is my best option.

I could buy an air impact wrench but I'm not looking to spend that much money at the moment given that I'm only attempting to take these forks apart because they're from an old bike and I feel like tackling a mini-project to help me learn something along the way. As far as I'm aware I've got the tools (a basic 1/4 socket 6 mm hex bit, alongside the extension bar and ratchet or a 6 mm hex allen key) to get the bolt out, and instead just need to find something to hold the damper rod still. I do appreciate the suggestion of an air impact wrench, mind, and will defiantly keep it on the list of "tools to buy" depending on how far I go into mechanics in the future.
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The do it all, T̶h̶e̶ ̶b̶r̶o̶k̶e̶n̶ ̶o̶n̶e̶,̶ ̶T̶h̶e̶ ̶b̶i̶g̶ ̶l̶u̶m̶p̶,̶ ̶C̶h̶o̶n̶g̶ ̶N̶o̶o̶d̶l̶e̶

[Jewlio Rides Again LLB]

You know you're in a bad way when Teffers is calling you out for being garbled

I *think* when I did it, I used a standard Allen key and held the stanchion with one of those rubber charity wrist bands to stop it just turning the whole thing aimlessly. Unless it was when i was removing the fork tops.
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[stinkwheel]

As has been mentioned above. Shoving/tapping a bit of broom handle in the top is the accepted way of stopping the damper rod spinning.

As you may see from all the above, this is a job most easily done with the legs still in the bike and the top nut still on, then they usually just crack off. Most of the time, the mudguard brace prevents the lowers turning like Jewlio describes.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[bikenut]

As suggested, compress the fork against the internal spring, which will increase pressure on the damper rod and hopeful;ly stop it from turning, allowing the allan bolt damper rod bolt to be undone/slackened.

Is it all corroded in the hole, a picture would help.

Using a broom stick etc means the spring will be out, thus loosing that way of preventing the damper rod from turning.

You could look down the fork inside and see if the damper rod has a hex internal for a long tool to go down inside the fork and sit in the hex, for damper rod allan bolt removal/slackening.

Have a look see. If there is one it may well be 14mm. If so a suitable 14mm flanged bolt welded to a suitable rod may make the tool you need.

Maybe some heat on the allan bolt and area may also help, hot air rather than flame.
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nuts about bikes

[rhys99]