A minor victory of the maintenance kind.

<snip>

Before you even try to insert the new bearings, have a word with the lkes of
WUN, or someone else who has a lathe and the skill to use it properly.
What you need before ruining your new ££££ drawn cup needle roller bearings,
is an insertion mandrel turning up on a lathe. This stops you collapsing the
relatively soft and thin outer shell of the bearing into the needles. Trust
me on this. If you try to insert them with anything else other than Yamaha
special tool #1234555, you *will* **** them up.
If you get stuck, email me the diameter of the hardened spindle and I'll
knock one up for you.
Cheers,
JB

 

It is if you have a lathe. My lathe has saved me an utter fortune in special
tools.

Now that's just getting a bit flash! I have to drive 40miles to use the one
at work. Oh for a bigger workshop.......


JB

 

Today I have been mostly getting the utterly shagged needle roller
bearings out of the rear suspension linkages on the YZ250. Well to be
exact the bearing shells, because that's all that was left of them in
the relay and control arms. The needles cascaded on to the floor in a
rusty shower when I eventually got the linkages off the swinging arm.


TMack's suggestion of pounding a thin screwdriver between the casing and
shell was attempted, but the shells didn't seem to want to deform before
producing a banana curved screwdriver shaft.

Then I tried heat and an improvised bearing driver (socket). Didn't want
to get the parts too hot[1] and so ultrasonically[2] cleaned them first
and popped them in the oven after consulting St Phil for the correct gas
mark. Transferred the pretty hot relay arm to somewhere I could wield a
lump hammer and struck up like the village smithy. One of the shells
moved about 4mm. Unfortunately I couldn't find anything to work as a
proper anvil with a suitable hole, so my oft used dodge of supporting it
over the head of a FOAD ring spanner was tried. At this point what lip
of the shell that was still intact cried enough, so back to the drawing
board and Google. I found a description of a method using a dremel and
die tool combined with TMacks thin screwdriver dodge. An experiment
revealed that my pikey B&Q dremel was capable of slotting the shell, but
I would have trouble slotting the entire length (certainly impossible on
the control arm which has two bearings like a mini swinging arm.

So off to B&Q for a brand new fine hackswaw blade as luckily a full
sized blade would pass through the shells with plenty of clearance.
Bearing shells are pretty hard, but after a fair while of careful sawing
I had nearly broken through to the alloy. A small screwdriver was bashed
in next to the slot and to my joy I could feel the shell giving. A sound
bash with a lump hammer (not easy to miss fingers given the size and
shortness of the object being hit) and the shell split and gave. Remove
screwdriver and insert finely tapered nail driver and bash again so that
the shell began to curl in upon itself. Grasp the curled in bit with
needle nosed pliers, give it another quick spray of Plusgas, twist and
haeve and, hey presto, the bastard was out. Repeat for the other four
bearing shells (except that the control arm with two next to each other
required a disproportionately greater sawing time to be sure not to cut
in to the alloy. The bruising of the internal surface wasn't too bad and
will clean up OK prior to inserting the new bearings (using the threaded
rod, washers and sockets method).

So that just leaves the swinging arm itself. The needles are still in
the bearings on that - although rusted so solid you can hardly see them.
I may still take that to Revs because I'm really not sure about giving
that some 'ommer without being able to support the pivot arm ends
properly. Might try heat and the puller method though.

[1] So how do you tell how hot alloy is getting safely without overdoing
it when using a blow torch? There's no way the swinging arm is going in
the oven.

[2] The ultrasonic cleaner has now well and truly justified its
purchase. Big enough to get even the control arm in. Thus not alerting
SWMBO to illicit domestic appliance use by the fragrance of burning
Plusgas.


--
+-------------------------------------------------------------------+
| Pete Fisher at Home: |
| Voxan Roadster Yamaha WR250Z/Supermoto "Old Gimmer's Hillclimber" |
| Gilera GFR * 2 Moto Morini 2C/375 Morini 350 "Forgotten Error" |
+-------------------------------------------------------------------+

 

Using the patented Mavis Beacon "Hunt&Peck" Technique, JB

Sounds easy enough.

Pete, I have a press too if you want to really do the job properly.

 

Your offer is appreciated, but the more I look at the Clymer manual and
google for 'swinging arm bearing removal' the more likely it is that I
will GAMI.

I did find a 'Motion Pro' tool that looked like a professional version
of the threaded rod and sockets trick. Unfortunately, the price is a bit
steep for just one-off use, though it might come in useful for the lad's
machines in the future if he gets the hill climb bug.

--
+-------------------------------------------------------------------+
| Pete Fisher at Home: |
| Voxan Roadster Yamaha WR250Z/Supermoto "Old Gimmer's Hillclimber" |
| Gilera GFR * 2 Moto Morini 2C/375 Morini 350 "Forgotten Error" |
+-------------------------------------------------------------------+

 

hahah

 

But, but, but... it's an excuse to buy a New Tool, man.

 

...

Modern (expensive) way - IR pyrometer (hand-held doohickey, point it at the
part and an LCD on the back reads the temp.)

Old (free) way - rub some soap / soapsuds on it, when it blackens it's as
hot as you want to get unless you want to cast it...

Intermediate - go to your local welding suppliers, they'll have temperature
crayons in all sorts of varieties, for making sure the ally you're welding
ain't getting a bit warm...

One thing to watch is "hot shortness" in ally, above a critical point it
goes brittle and can crack unexpectedly - DAMHIK, OK?

If the idea is to bend the ally, get it to suitable temp and quench it (dunk
it in a bucket of water) - heat-treatment's pretty much the opposite of
steels - then restore the temper/hardness by heating it for a long period
and letting it cool very very slowly

Dave H.

 

In communiqué <Xrycn.301532$2>, Dave H.

Sounds my style.

Not sure just how high tech the alloy is. It's very light for a swinging
arm - might be high magnesium content.

I'm going off the idea.

I certainly don't want to bend this.

I managed to get the new needle roller bearings in to the linkages today
fairly easily using a tool improvised from a long 12mm hex head set
screw and suitable washers and spacers. A good heat differential was
created and then they pulled in to place without drama. Assembled with
moly grease and bolted up they now pivot smoothly without play.

The swinging arm looks a different kettle of fish. I think I'll quit
while I'm ahead and take it to Revs.


--
+-------------------------------------------------------------------+
| Pete Fisher at Home: |
| Voxan Roadster Yamaha WR250Z/Supermoto "Old Gimmer's Hillclimber" |
| Gilera GFR * 2 Moto Morini 2C/375 Morini 350 "Forgotten Error" |
+-------------------------------------------------------------------+