Crap, stripped cable bolt on Dura Ace Rear Derailleur

[andy]

subject line says it all. I have stupidly overtightened and stripped the
derailleur body where the cable mounting bolt screws in. Is there any fix
for this? It looks like there is enough meat to tap it out or install a
helicoil. Is it necessary to take the derailleur apart? Any been there done
thats? Thanx in advance.
Andy (now i know why i was keeping that spare ultegra derailleur around)

[Andre]

Possibly you could ream out the hole, and install a longer nut-and-bolt to
replace the original. I believe there's enough space on the back side of the
anchor plate that will allow placement of the nut. Of course, it will be
tough to position a vice grip on the nut when tightening the bolt...
--
--------------------------
Andre Charlebois
AGC-PC support
http://agc-pc.tripod.com
BPE, MCSE4.0, CNA, A+

Post by andy
subject line says it all. I have stupidly overtightened and stripped the
derailleur body where the cable mounting bolt screws in. Is there any fix
for this? It looks like there is enough meat to tap it out or install a
helicoil. Is it necessary to take the derailleur apart? Any been there
done thats? Thanx in advance.
Andy (now i know why i was keeping that spare ultegra derailleur around)

[Leo Lichtman]

"andy" wrote: (clip)It looks like there is enough meat to tap it out or
install a

Post by andy
helicoil. Is it necessary to take the derailleur apart? Any been there
done thats?

^^^^^^^^^^^
What is the frame made of? I have used various methods to restore stripped
threads, but never on a bicycle frame. Helicoils work really well, and in
my opinion, the new thread is stronger than the original. Helicoil even
makes a repair for replacing the stripped helicoil. Never used that,
though. If it's a steel frame, you could weld or braze the hole, and retap.
Loctite makes an epoxy type product that can be used to reform the stripped
threads.

[Richard Tack]

Post by Leo Lichtman
"andy" wrote: (clip)It looks like there is enough meat to tap it out or
install a

Post by andy
helicoil. Is it necessary to take the derailleur apart? Any been there
done thats?

^^^^^^^^^^^
What is the frame made of? I have used various methods to restore stripped
threads, but never on a bicycle frame. Helicoils work really well, and in
my opinion, the new thread is stronger than the original. Helicoil even
makes a repair for replacing the stripped helicoil. Never used that,
though. If it's a steel frame, you could weld or braze the hole, and retap.
Loctite makes an epoxy type product that can be used to reform the stripped
threads.

I think the stripped thread is in the
der frame that the cable clamp screws
into. If it was a steel der *hanger,*
then a helicoil/retap is in order. If an
alloy frame a dropout saver

http://www.bikepartsusa.com/product_info.phtml?p=01-102378

is the fix.

[Jay Beattie]

Post by andy
subject line says it all. I have stupidly overtightened and

stripped the

Post by andy
derailleur body where the cable mounting bolt screws in. Is

there any fix

Post by andy
for this? It looks like there is enough meat to tap it out or

install a

Post by andy
helicoil. Is it necessary to take the derailleur apart? Any

been there done

Post by andy
thats? Thanx in advance.

Can't you just tap it out to 6mm? I have done this on a front
derailleur, but not a rear. A helicoil is only necessary if you
are trying to match threads, which you do not need to do, being
that you do not have to use a 5mm bolt and M6 cap bolts are
common as fleas. -- Jay Beattie.

[andy]

The stripped area is in the derailleur, not the frame, but thanx for the
suggestions when I screw up my frame(!). I am thinking just tapping the hole
out to the next size metric bolt. In the past when I have tapped something
out, I have had more space 'behind' the area being tapped. In this case the
derailleur spring is pretty close. Thanx for the suggestions and keep em
coming.
andy

Post by andy

Post by andy
subject line says it all. I have stupidly overtightened and

stripped the

Post by andy
derailleur body where the cable mounting bolt screws in. Is

there any fix

Post by andy
for this? It looks like there is enough meat to tap it out or

install a

Post by andy
helicoil. Is it necessary to take the derailleur apart? Any

been there done

Post by andy
thats? Thanx in advance.

Can't you just tap it out to 6mm? I have done this on a front
derailleur, but not a rear. A helicoil is only necessary if you
are trying to match threads, which you do not need to do, being
that you do not have to use a 5mm bolt and M6 cap bolts are
common as fleas. -- Jay Beattie.

[Jim Smith]

Post by andy
The stripped area is in the derailleur, not the frame, but thanx for the
suggestions when I screw up my frame(!). I am thinking just tapping the hole
out to the next size metric bolt. In the past when I have tapped something
out, I have had more space 'behind' the area being tapped. In this case the
derailleur spring is pretty close. Thanx for the suggestions and keep em
coming.

If the clearance behind the hole is a problem, you could use a bottoming tap.
These are only chamfered for one or two threads.

[Leo Lichtman]

Andy wrote: (clip) In the past when I have tapped something out, I have had
more space 'behind' the area being tapped. In this case the derailleur
spring is pretty close. (Clip)
^^^^^^^^^^^^^^^^^
If there is not enough room to retap, you will not be able to use a
Helicoil. They require the hole be tapped to a special oversize thread to
receive the replacement insert.

[Jim Smith]

Post by Leo Lichtman
Andy wrote: (clip) In the past when I have tapped something out, I have had
more space 'behind' the area being tapped. In this case the derailleur
spring is pretty close. (Clip)
^^^^^^^^^^^^^^^^^
If there is not enough room to retap, you will not be able to use a
Helicoil. They require the hole be tapped to a special oversize thread to
receive the replacement insert.

Bottoming taps are available for helicoils. No problem putting a
helicoil in a blind hole.

[andy]

I think Leo is thinking not enough material around the current hole, I have
enough material. It is the space on the other side of the hole for the tap
to go through. I will look into a bottoming tap, thanx guys.
andy

Post by Jim Smith

Post by Leo Lichtman
Andy wrote: (clip) In the past when I have tapped something out, I have had
more space 'behind' the area being tapped. In this case the derailleur
spring is pretty close. (Clip)
^^^^^^^^^^^^^^^^^
If there is not enough room to retap, you will not be able to use a
Helicoil. They require the hole be tapped to a special oversize thread to
receive the replacement insert.

Bottoming taps are available for helicoils. No problem putting a
helicoil in a blind hole.

[A Muzi]

Another Andy wrote: (clip) In the past when I have tapped something out, I have had
more space 'behind' the area being tapped. In this case the derailleur
spring is pretty close. (Clip)
If there is not enough room to retap, you will not be able to use a
Helicoil. They require the hole be tapped to a special oversize thread to
receive the replacement insert.

The RD7800 (and most current Shimano products) has a steel
insert for the anchor bolt which may be pressed out and
replaced with another from a scrap derailleur or the similar
nut found in cheap MTB shifters and cable calmps.

[Jay Beattie]

Post by andy
The stripped area is in the derailleur, not the frame, but

thanx for the

Post by andy
suggestions when I screw up my frame(!). I am thinking just

tapping the hole

Post by andy
out to the next size metric bolt. In the past when I have

tapped something

Post by andy
out, I have had more space 'behind' the area being tapped. In

this case the

Post by andy
derailleur spring is pretty close. Thanx for the suggestions

and keep em

Post by andy
coming.
andy

What are you talking about? I thought you stripped the thread
for the cable anchor bolt on the derailleur -- which, IIRC, is
5mm threaded aluminum. Why can't you tap it to 6mm and use an M6
cap screw? This seems very easy. I have tapped front derailleur
anchor bolt holes which have a little more material, but there
should be no problem with a rear derailleur. A helicoil is a
total waste of time. If you have enough material to drill out
and screw in a helicoil, you have enough room to tap it out to
6mm. -- Jay Beattie.

<snip>

[Leo Lichtman]

"Jay Beattie" wrote: If you have enough material to drill out and screw in
a helicoil, you have enough room to tap it out to 6mm.
^^^^^^^^^^^^^
Basically, I said the same thing, except in the negative sense. But. if I
had a choice between tapping oversize or using a Helicoil, I would choose
the Helicoil, for the following two reasons: 1.) A helicoil is made of
stainless steel, and produces a thread that is not going to strip again.
This is a big plus if you are repairing aluminum. 2.) You wind up after
the repair with standard parts.

However, a Helicoil kit, if you have to buy it for this one job, is probably
not worth the cost, and I would certainly consider tapping to the next size
a good alternative.

[dianne_1234]

On Fri, 01 Oct 2004 16:10:18 GMT, "Leo Lichtman"

Post by Leo Lichtman
"Jay Beattie" wrote: If you have enough material to drill out and screw in
a helicoil, you have enough room to tap it out to 6mm.
^^^^^^^^^^^^^
Basically, I said the same thing, except in the negative sense. But. if I
had a choice between tapping oversize or using a Helicoil, I would choose
the Helicoil, for the following two reasons: 1.) A helicoil is made of
stainless steel, and produces a thread that is not going to strip again.
This is a big plus if you are repairing aluminum. 2.) You wind up after
the repair with standard parts.
However, a Helicoil kit, if you have to buy it for this one job, is probably
not worth the cost, and I would certainly consider tapping to the next size
a good alternative.

I wonder if changing the M5 cable anchor bolt to M6 might change the
derailleur function? You know, like mounting the cable in a different
spot to make it shift with Campy levers or something.