Crown race on French fork.
Peter Howard
bottom of the range, seamed manganese steel tubes neatly fillet brazed.
Problem is front fork which had an absolutely shot headset. I believe that the
French adopted the ISO standard for forks and headsets in the early '80's and
this fork accepts a 22.2mm stem and the threaded top race and locknut from a new
ISO headset I have.
The fork crown race seat inexplicably measures an even 26mm and the crown race
in my new parts kit is 26.4mm I.D. Every other threaded 1" fork I've ever worked
on took either 26.4 or 27mm I.D. crown race. Machining marks are clearly visible
on the fork seat so it seems to have been made that way to suit a weird
undersized crown race.
What now? My first thought was to butter up the seat with JB Weld, drop the race
on and set it aside to cure well. Has anyone ever tried this and how long did it
work?
This is not a great bicycle. It came out of a dumpster and it's only saving
grace is the niceish wheels it came with. I was planning on making the bike into
a single speed freewheel fun bike so any complicated or expensive fixes won't be
worth the trouble.
PH
thirty-six
> I'm messing about with a circa 1990 Peugeot Aubisque, about third from the
> bottom of the range, seamed manganese steel tubes neatly fillet brazed.
> Problem is front fork which had an absolutely shot headset. I believe that the
> French adopted the ISO standard for forks and headsets in the early '80's and
> this fork accepts a 22.2mm stem and the threaded top race and locknut from a new
> ISO headset I have.
>
> The fork crown race seat inexplicably measures an even 26mm and the crown race
> in my new parts kit is 26.4mm I.D. Every other threaded 1" fork I've ever worked
> on took either 26.4 or 27mm I.D. crown race. Machining marks are clearly visible
> on the fork seat so it seems to have been made that way to suit a weird
> undersized crown race.
>
> What now? My first thought was to butter up the seat with JB Weld, drop the race
> on and set it aside to cure well. Has anyone ever tried this and how long did it
> work?
It's been done with regular epoxy and is certainly not a permanent
repair. A metal filled epoxy may have better success but personally I
would be inclined to use a shim. Although you may not be able to find
0.2mm material (check the smaller 5oz drinks cans) you do not have to
shim all the way around to make an effectual repair It will distort
the race but that's something you live with, use a cheap headset or
get some braze built onto the seat.
Peter Cole
I had a similar problem with a fork that I thought was JIS (27 mm) but
turned out to be 26.4 after I ordered a JIS headset. I shimmed it with a
bit of aluminum can. That was 5 years (and many miles) ago. Epoxy might
work (I'd be surprised), but you'd still have the problem of centering
the race.
thirty-six
I doesn't need to be centred. A mm here or there makes no difference .
landotter
wrote:
JB Weld tends to do well under compression in my experience. Give it a
shot, and yes, do let it cure a few days before riding on it.
thirty-six
There's a point, if you do use the epoxy, use the slowest setting one
you can find (usually marked as 24hrs) and give it twice as long with
a little warmth (blood) continuously . This will give the strongest
set whether for JB or any other epoxy.
thirty-six
wrote:
> On Wed, 26 May 2010 06:40:00 -0700 (PDT), thirty-six
>
> <thirty-...@live.co.uk> wrote:
> >> JB Weld tends to do well under compression in my experience. Give it a
> >> shot, and yes, do let it cure a few days before riding on it.
>
> >There's a point, if you do use the epoxy, use the slowest setting one
> >you can find (usually marked as 24hrs) and give it twice as long with
> >a little warmth (blood) continuously . This will give the strongest
> >set whether for JB or any other epoxy.
>
>
> Go down to Home Depot and buy a roll of Aluminum duct tape. It's in
> the HVAC department. It's very thin. Wrap as much as you need to fill
> it out.
>
> Solid metal, no worries, it will be centered within thousandths.
> Should last a long time... won't break free like epoxy when you're
> miles from home.
I'd go with that, just could not remember before where thin metal tape
was used.
landotter
<noEmailto...@stillnodomainey.com> wrote:
> On Wed, 26 May 2010 06:40:00 -0700 (PDT), thirty-six
>
> <thirty-...@live.co.uk> wrote:
> >> shot, and yes, do let it cure a few days before riding on it.
>
> >There's a point, if you do use the epoxy, use the slowest setting one
> >you can find (usually marked as 24hrs) and give it twice as long with
> >a little warmth (blood) continuously . This will give the strongest
> >set whether for JB or any other epoxy.
>
>
> Go down to Home Depot and buy a roll of Aluminum duct tape. It's in
> the HVAC department. It's very thin. Wrap as much as you need to fill
> it out.
>
> Solid metal, no worries, it will be centered within thousandths.
> Should last a long time... won't break free like epoxy when you're
> miles from home.
That'll work as well. I'd use whichever was closest in the tool box.
With JB, it's just filling a 0.2mm gap, not really taking the product
to its limits. If it failed on the road, you could still ride a
slightly sloppy headset--though I very much doubt that would ever
happen. Tape's easier to reverse.
AMuzi
I would knurl the crown race seat for 0.2mm.
In a pinch you could stake it.
--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971
Chalo
>
> I'm messing about with a circa 1990 Peugeot Aubisque, about third from the
> bottom of the range, seamed manganese steel tubes neatly fillet brazed.
> Problem is front fork which had an absolutely shot headset. I believe that the
> French adopted the ISO standard for forks and headsets in the early '80's and
> this fork accepts a 22.2mm stem and the threaded top race and locknut from a new
> ISO headset I have.
>
> The fork crown race seat inexplicably measures an even 26mm and the crown race
> in my new parts kit is 26.4mm I.D. Every other threaded 1" fork I've ever worked
> on took either 26.4 or 27mm I.D. crown race. Machining marks are clearly visible
> on the fork seat so it seems to have been made that way to suit a weird
> undersized crown race.
The best remedy is the same as for all other French (non)standard
parts:
Pitch into recycle bin. Sell for a few cents a pound, and devote the
proceeds towards getting a real bike.
Chalo
verktyg
It's classed as a bearing mount material and can fill a gap up to 0.020"
(.5mm). It's designed to provide quick repairs on machinery.
You can find it at bearing suppliers and some auto parts stores.
Chas.
"Peter Howard" <bbrov...@bbbigpond.net.au> wrote in message
news:Sj4Ln.27253$pv.2...@news-server.bigpond.net.au...
Peter Howard
"Chalo" <chalo....@gmail.com> wrote in message
news:8584600d-abe1-421e...@m33g2000vbi.googlegroups.com...
>
> The best remedy is the same as for all other French (non)standard
> parts:
>
> Pitch into recycle bin. Sell for a few cents a pound, and devote the
> proceeds towards getting a real bike.
>
> Chalo
Do I detect a faint note of negativity towards French velocipedes? I feel the
same way about Nottingham Raleighs.
PH
Peter Howard
"verktyg" <verkt...@aol.com> wrote in message
news:kO2dncERPctk12PW...@giganews.com...
> Loctite makes a product, 660 Quick Metal for just this kind of problem.
>
> It's classed as a bearing mount material and can fill a gap up to 0.020"
> (.5mm). It's designed to provide quick repairs on machinery.
>
> You can find it at bearing suppliers and some auto parts stores.
>
> Chas.
Thanks for the good suggestion. Next time I will try the Loctite 660. I went and
read their online information and it sounds like a possibility for this and
other bicycle applications.
Thanks very much to all other respondents. If this was a valuable velo I'd
certainly do the rounds of the LBS's to see who has a crown seat knurler.
However, I have already gone the JB Weld route with added refinement of several
turns of narrow aluminium popcan shim to centralise race and following the JB
Weld peoples advice re adding a little low level heat in latter stages of
curing.
We will see how it goes.
Have a good fall-back possibility if this doesn't work. Ratted through my
mountain of bicycle detritus and surfaced with a nice lugged fork off an
Australian Ricardo. It has EXACTLY the same steerer tube length plus a good
crown race already fitted and the steerer is stamped Tange, Made in Japan. Only
reason I don't use it straight off is that I'd have to repaint it.
PH
thirty-six
> "verktyg" <verktygj...@aol.com> wrote in message
Of course you may not have to wait for the bodge to fail because after
a few weeks you should be itching to know how the tange tubed forkset
performs. I believe some were chosen much for track bikes. I assume
due to a combination of price and grade of material in correct gauges
for track racing.
Chalo
>
> Chalo wrote:
> >
> > The best remedy is the same as for all other French (non)standard
> > parts:
> >
> > Pitch into recycle bin. Sell for a few cents a pound, and devote the
> > proceeds towards getting a real bike.
>
> same way about Nottingham Raleighs.
Yeah, those too.