Bultaco 250 Sherpa restoration

[Ainsley]

Yeah, you are right.  I removed both nuts and twatted it with a hammer, either side.  It did not budge and I didnt want to mess up the threaded ends.  It moves up/down fine, no side to side play.  But the swing arm pivot doesn't want to come out.  I shall squirt some grease in the grease nipple and soak the pivot in some release fluid overnight and try again.

[boghopper350]

Try not to "****" the ends with a hammer. Use lots of heating of all ares with a blow torch or heat gun and cooling cycles. Perhaps use a bit of oak or other hardwood on the end of the pivot bar to stop the damage when "********" it, but only when you are happy that things are moving slightly. Most of all be patient plenty of soaking will help as you suggested. 

Edited November 22, 2021 by boghopper350

[turbofurball]

If you can borrow an induction heater (a proper pro one) they work wonders on these.

It's worth the effort, there will be old dry grease in there that won't take kindly to suddenly being asked to work for a living

[Ainsley]

Good advice, thanks guys.  I will set about it as you suggest.

[trialsrfun]

I installed a grease nipple to the pivot tube on my Model 124 then its easy to keep it greased without having to dismantle it but obviously it would be best to remove it now to ensure everything is okay.

This stuff is pretty good at freeing things off WD-40 Specialist Fast Release Penetrant 400ml (toolstation.com)

[turbofurball]

1 hour ago, trialsrfun said:

I installed a grease nipple to the pivot tube on my Model 124 then its easy to keep it greased without having to dismantle it but obviously it would be best to remove it now to ensure everything is okay.

My Cota 349 has one, when I bought the bike I dutifully squeezed fresh grease in, then a bit later while the engine was out I figured it would be good to check what state the bushings were in ... my fresh grease had just made a thin path of least resistance, leaving about 90% of the old dry stuff in place.

They work great if used regularly, though

[woody]

Usually, once the spindle siezes in, it's siezed for good

There are two kinds of bushes for the swingarm. The original bronze outers with steel inners, or, the Miller type rubber bush with steel inner and outer. You should be able to tell which you have by looking, the original bushes both have collars on their outer edge. The inner steel bushes touch in the middle so that when the bolts are tightened the frame contacts with the outside face of the inner bushes and pushes them together. This leaves the outer bushes free to revolve around the inners when the swingarm moves as the inners are now fixed in place. You should see the two collars.

If you have the rubber bushes there is a spacer between the swingarm and the frame to take up the gap that would normally be filled with the collars of the original type bushes

In either set up, the spindle siezes by corrosion in the inner steel bush and usually it's stuck for good and you need to replace the whole bush/spindle assembly

If you can't shift it you're going to have to carefully cut through it both sides between the arm and the frame to remove the arm. If you have the original bushes you should then be able to grind or cut off the collar, or what's left of it, from the inner bush on one side and then drift the spindle and inner bushes as one assembly out of the other side, leaving just the outers to then remove

If you have the rubber bushes you might have to drill all around the rubber to break it up on both sides (burning with a torch helps but they won't usually melt the rubber, it's so hard - a proper oxy acetylene torch probably will)  Once the rubber is broken up you can again drift the spindle out with inner sleeves leaving just the outers to remove

Whichever way, it can be a bitch of a job.

With working bushes, even if you have a grease nipple (as not all do) it pays to take the arm off and grease the inner bushes and spindle once a year if the bike  is used

[Ainsley]

Ah, OK.  I will go and inspect it in the morning, now you have provided that explanation Woody, thanks.

I did pump grease into it till I could force no more in with the grease gun.  It seemed to go in easy, then firm up and now the swing arm still pivots up/down, but there is resistance that wasn't there before..  Im assuming the new grease has gone in displacing the old crap.  I've laid it down on its side and poured as much Holts freeing up fluid down the shaft and left it for the night.  I will inspect it tomorrow and ascertain if its rubber or original bushes. 

[woody]

With ruibber, even if  the spindle is siezed solid in the inner sleeve it won't affect the swingarm movement up and down, it will still move as normal as the inner and outer sleeves are bonded to the rubber sandwiched inbetween. The outer sleeve rotates around the inner and the rubber twists with it which is the resistance you can feel. They're crap (in my opinion that is) and the bronze/steel bushes work better with no resistance on the swingarm which is what you want, the smoothest and most free swingarm movement

[larry s. k.]

Hi just love it , we all  bike rebuilders have crossed this , problem   Woody so right it’s old prob serious froze $$ , ,  to leave it , or continue , torch , saw electric  , , then find vice to remove center ,  with long thin chizel ,  easier with helper ,, or , phone local shop,  and get estimate  over phone , before you go into shock , , I done a few , my little Rickmans , we’re a real test of my nerves ,  good luck and cheers 

[sherpa325]

The issue is that the spindle is basically corroded to the inner sleeve and any grease that is applied only goes between the inner and outer sleeve [the part that actually moves] and won't get to the spindle. In the past I have drilled one stubborn one out by using increasingly larger drills, starting off with say a 5mm and increasing by a couple of mm each go. Most spindles already have the centre pre drilled and you only have to go in about 15mm deep to clear the frame on each side. This method at least gets the swinging arm out of the frame without damaging the frame or the swinging arm and gives you access to the swinging arm to have a more determined go on your bench.

[turbofurball]

Now I'm wondering if there's a neat way to press them out in one go without breaking anything

[b40rt]

4 hours ago, turbofurball said:

Now I'm wondering if there's a neat way to press them out in one go without breaking anything

Probably not ....

[Ainsley]

After much heating, greasing and soaking in release fluid, I seem to have one end free.  The spindle, inner bush and swingarm are all now independent moving on the RH side.  Only the LH side does the inner bush not move free from the spindle. 

So some progress, just need to see if I can free up the other side.  I've left it soaking again after a morning of heat, grease and lube persuasion.  Time for a cuppa and then try again.

[Ainsley]

Hi, I've now stripped the frame down and want to get it back to the original colour.  Its been badly painted back, which is not right.  So, once cleaned up, what colour should it be ?  From photos I can see its silver, but is there a correct sliver it should be ?

Thanks.