The BSA A7-A10 Forum

Technical => Frame => Topic started by: roadrocket on 17.04. 2013 21:53

Title: Fork slider dented
Post by: roadrocket on 17.04. 2013 21:53

I have been forced to dismantle my newly fitted forks, because one leg was stuck in the slider. It turns out that there is a dent in it. Is there a way to remove this with shed-ready tools?

Cheers, Otto in Denmark
Title: Re: Fork slider dented
Post by: muskrat on 17.04. 2013 22:15
I doubt it Otto.
Maybe a small grinder on a long shaft in the dremel. *eek*.
Even set up in a lathe would be tricky.
Title: Re: Fork slider dented
Post by: bsa-bill on 17.04. 2013 22:16
yes but not for the purists and needs a lot of patience and just for very slight dents (not for ones you can see)

For  dents you can see first thought was heat, can be done but you have to heat opposite the dent as well as on the dent to prevent distortion, I considered this beyond my skills, really to be done by someone who uses heat on a fairly regular basis like a mechanic in a shop, but if you know somewhere it could be done might be good.

I had a very slight dent on one leg (due to twisting in the vice when removing the seal) So my method, a bit unrefined but did work, put the old bush on the stanchion, smear some grinding paste on the dent and work the stanchion around the dent area a little at a time until it slides up and down, use coarse paste first and switch to fine, stop and wash out the whole thing whenever paste gets anywhere else than around the dent, takes a lot of time but I got the leg to slide freely with new bushes fitted and not slack at all
Title: Re: Fork slider dented
Post by: chaterlea25 on 18.04. 2013 00:19
Hi All,
adding grinding paste will remove metal all around the slider  *eek* You dont want to do that !!

I made a tool from an old fork leg and bushes, brazing a piece of tool steel to the end of the leg this then had to be ground very carefully so as it would only cut where the dent was, it took several go's before it had removed enough
If I were to do it again I would try and make the tool bit adjustable somehow????

The correct "tool would be a "David Brown" reamer, but they are very expensive!!!!

Title: Re: Fork slider dented
Post by: KiwiGF on 18.04. 2013 07:13
Maybe make a plug up that JUST FITS in the slider and hammer it passed the dent, making sure you have a way of getting it out of course  *eek*

Or make up a split collar that is slightly smaller dia than the outside of the tube, clamp it all up in a vice and rotate the leg, thats how to remove dents from bicycle frames but it worked on my a10 downtubes which were dented from sidecar brackets  i think...

It would be possible to make a split plug that fits inside the tube and a hammer a tapered rod through it, but thats starting to get well past the average shed abilities...

The probelm you have is the tubes are pretty accurately bored even a couple of thou out of round may cause sticking
Title: Re: Fork slider dented
Post by: Tomcat on 18.04. 2013 10:05
KiwiGF is on the money, I tried a few methods but ended up making a mild steel copy of the staunction and bush. Clamp it in the vise, tap on the slider then light panel beating beside the dent.  I hope that makes sense, I had no luck resizing the photo of it. Tomcat
Title: Re: Fork slider dented
Post by: bsa-bill on 18.04. 2013 10:24
adding grinding paste will remove metal all around the slider  eek You dont want to do that !!

no you don't and I didn't
Thought I went to pains to explain only put paste on the dent, don't twist the stanchion just up and down enough on the dent and wash out often.
Also this I said was a very small dent could just be felt with a finger but not seen really, and used an old stanchion and bush with a bit of Tomcat 's tapping, eventual the bush went down past the tight spot, at that point I sacrificed a new bush and started over but used solvol metal polish.

TBH not a method to be proud about but it worked for me and 60 miles from an engineering shop that could do it at the time it was needs must.
The guy I talked to about heating it works in a shop just 15 miles from me but they couldn't give me when a date due to work load
Title: Re: Fork slider dented
Post by: Jules on 18.04. 2013 13:33
I've used Bill's method in my tubes too, they had small (like stone/rock(?) impacts) and also some corrosion when the bike had been bush bashed and parked up. I made up a wooden "leg" with flats and used fine wet and dry paper to clean them up inside - it seems to have worked successfully because the bearings fit & slide well BUT the bike is still far from complete, hence not road tested yet!
Title: Re: Fork slider dented
Post by: roadrocket on 18.04. 2013 19:11
OK, I've rigged up a makeshift device; an old fork stanchion, with and old upper bush running freely. On the far end I have superglued less than half the circumference of a lower bush, onto which I have glued a piece of emery cloth. Before I did that, I rammed the old stanchion/lower bush repeatedly past the dent, with some persuasion. Now the idea is that the piece of lower bush with emery cloth can be brought to bear precisely and squarely on the dent. We'll see how it goes, the contraption is now left to settle overnight.

Otto in Denmark
Title: Re: Fork slider dented
Post by: roadrocket on 22.04. 2013 20:34
Just to round this one off; in the end I took Muskrats advice of fitting a grinder on a length of aluminium tube. It was quite easy to hit the High spots, and I don't Think I have removed too much metal from the wrong places. Bouncing is now restored, but I have not taken it for a spin yet, due to want of a front brake cable.