MX250 Swing Arm Removal.

[mx250]

Specifically the pivot shaft removal (Part#2 in attached). Everything is undone and loose. The shaft turns freely, swing arm moves freely, there is clearance between swing arm and frame.

Pretty obvious the shaft is rusted to Part# 3 I would guess (why, it should be smothered in grease  ).

If so, how do I get the shaft out? Heating the swingarm seems to be ineffectual (in theory and practice). A press would be good (and cumbersome). That's what I'm think at the mo, car jack, brick walls, shit of of time and effort :'(.

Any experience? Any suggestions?

http://www.yamaha-motor.com/partviewer/default.aspx?ls=sport#/Yamaha/MX250A_-_1974/REAR_ARM_-_REAR_CUSHION/MX250A_%281974_MOTORCYCLE%29/REAR_ARM_-_REAR_CUSHION_%28MX250A_-_1974%29

[Nathan S]

Car jack to slightly spread the frame away from the swingarm, then a hacksaw through the gaps.
 An MX250 frame, being built like a brick shithouse, may not be a good frame to use this method on...

[mainline]

Those super thin 125mm angle grinder cutting discs do the trick

[mx250]

WWWHHHAAATTT!

There's no other way?

I lose the Pivot bolt that way :'(. And then I have to get the pivot shaft out of the swing arm as well .

[Freakshow]

its th eonly way, if you beat it and it wont come out you muchroom the end and you back to square one.

you can try taking out the grease nipple and filling it daily with brake fluid and a little air.  i have had the same thing lotsa time, in the end the thin grinder comes out.  you can buy the bolts from bolt places as it just mild steal and its a standard size for some kinda machine as they had them last time i went looking.

and then you also dont waste the seals and bushes as you heat it up and melt everything else on the way.... kinda brutal but works out as the cheaper option loing tern.   

[mx250]

Thanks.

Knowing it the best and only way will save a lot of grief/heartache/head scratching/soul searching/lip biting .

[Iain Cameron]

I used a electric hacksaw dont know its real name looks like a drill but the blade is up and down .

[Tossa]

I use a socket on a bar with 3lb knockometer works for me every time

[mx250]

I use a socket on a bar with 3lb knockometer works for me every time

I might try that Tossa, nothing to lose . Gunna destroy the shaft anyway. Might be easier than springibng the frame apart. Thanks

[Nathan S]

I lose the Pivot bolt that way :'(. And then I have to get the pivot shaft out of the swing arm as well .

Once you've cut the bolt, the sleeves that its rusted into, will simply slide out of the bushes.
You will stand a reasonable chance of getting the bolt out of the sleeves (so you can re-use the sleeves), once its not stuck in the frame and/or swingarm.

[GMC]

how do I get the shaft out?

The same way diamonds are made, heat & pressure.

Lay the frame sideways over something solid, use a piece of heavy wall pipe big enough for the pivot bolt to go inside and place under the frame. Place the pipe against the frame with the biggest contact point available where it is least likely to cause damage.
Then use a soft metal drift (alloy or brass) against the pivot bolt to hit against. The soft metal will crush instead of the bolt.
Some heat can help to dislodge things.
A press is good for this but a hammer will do fine. Keep the line of force on something solid, either concrete slab or over the leg of a solid bench.
If this fails then you have to sacrifice the easiest to replace part, which is the bolt.
As others have said, spread the frame enough to get a thin cut off disc or similar to get through.
Once the arm is out you can go back to the pressure thing to get the parts out of the arm,
or just buy another swingarm

Careful how much pressure you apply, watch carefully as you go.
Just blindly using force can damage the frame and then you have to find some gullible fabricator to repair it

[mx250]

Success . I went the big knockometre method (I thought spreading the frame would stress it because the frame is braced strongly close to the swing arm mount).

The pivot shaft is screwed  . That damaged was done inside the tube by the drift. That was after a half gallon of WD40 - it wouldn't come out. Lubed what shaft was out, 120mm, drove it in again, then whacked it again from the other side and it just about fell out

All's well that ends well but why do I muck with this old shit .

[Freakshow]

NOw if you put a new bolt back in, run a length of sanding or lathe across the middle section, thats were they seam to grow.  if you can take off even a mm with a file, beltsander, wheel in that middle section of the new bolt it seems to hold grease and have enought clearance that if it does rust and grow or pack full of dry shit, there is enought of a gap for it to roll over and slip past.   JUst a thought for the next person to get your bike. 

[Tossa]

See when in doubt give it a clout!! and when it finally comes apart it's very theraputic.  Like "Take that you bastard"