1 3/8 spindle updat and more questions

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Hi All,
this post is an update on one i did a few weeks ago regarding a modified swingarm cradle. So after working out my swing arm cradle had a modified spindle tube i ordered a new swingarm spindle/seal etc kit and went to work. I drilled a hole for the centre locating bolt, drilled and tapped m6 threads to keep the spindle in place on the flats. After pressing the new bushes into the swingarm it would not slide onto the cradle, the modified spindle tube which had been fitted was protruding past the cradle plates so i ground it down until i could get the swing arm on,it was a tight fit but went on with some force applied. After pressing the bushes into the swing arm they compressed and needed to be reamed so i did it with sand paper wrapped around a shaft on my drill, the spindle went through the bushes but was a tight fit. The spindle was was also a tight fit in the spindle tube bushes on the cradle and had to be knocked in with a drift. After getting all of this together and the bolts snugged up the movement of the swing arm is very tight. I put a screw driver through where the axel runs, put the swing arm horizontal and placed weights on it until it dropped. It took 7kg all up. Now the question to the experts out there if anyone can help me out, does this seem excessively tight? I thought i was better to keep things tight considering that that it may loosen up a bit over time but i think this may be a bit much. I am still at the stage where i can drift the spindle back out and relieve the bushes a bit more. Any input would be really appreciated

1 3/8 spindle updat and more questions


1 3/8 spindle updat and more questions


1 3/8 spindle updat and more questions


1 3/8 spindle updat and more questions
 
Hi Morton,
Nice job you are doing there!

Personally I think that's too tight. Don't forget you need to add the weight of the swinging arm to your 7kg. I think it should drop (slowly) with no additional weight. I think it would be better to get it line reamed so that the bushes are aligned. Using the sandpaper method won't give you the level of accuracy, and some of the abrasive may embed itself into the bush, shortening their and the spindle's life.

Like I say this is my personal opinion, others may disagree.


Cheers,

cliffa.
 
Should be able to swing it through it's arc with one hand, and not feel much resistance at all; releasing the swingarm should have it dropping on it's own weight.
 
morton said:
After pressing the bushes into the swing arm they compressed and needed to be reamed so i did it with sand paper wrapped around a shaft on my drill, the spindle went through the bushes but was a tight fit. The spindle was was also a tight fit in the spindle tube bushes on the cradle and had to be knocked in with a drift. After getting all of this together and the bolts snugged up the movement of the swing arm is very tight. I put a screw driver through where the axel runs, put the swing arm horizontal and placed weights on it until it dropped. It took 7kg all up. Now the question to the experts out there if anyone can help me out, does this seem excessively tight? I thought i was better to keep things tight considering that that it may loosen up a bit over time but i think this may be a bit much. I am still at the stage where i can drift the spindle back out and relieve the bushes a bit more. Any input would be really appreciated

well,... The swingarm 'axle' is fixed to the cradle's swingarm tube by the set screws that you installed. Your very tight fit in the swingarm tube is just more insurance against play developing there. (which was an issue on early commando's with only a single central fixing bolt, and the reason later commandos had 2 additional 'wedge' bolts to correct the poor design of early commandos) You've addressed that deficiency nicely, so don't worry about the swingarm tube....

Now the swingarm bushes mounted in the swingarm are where the pivoting of parts takes place. The fact that you reamed it by hand, may have left some imperfections in the fit between round axle and reamed bushing, so it's good that it's tight NOW because high spots wear down fast because they focus the force on a small area, not the entire surface of the bushing when the fit is machined perfectly round. IF I were you,... I wouldn't ream it further. I would bet that your 7kg's of force will be fine.

Of course... that's just my opinion... I actually have a 70 commando which had the very sloppy swingarm tube fit with the early commando single center bolt design. It handled terribly until I did the "kegler clamp" swingarm tube modification. Now my bike handles very nicely. I think you're good to go as is. Looking nice!
 
Thanks all for the feedback to my last post its all of great assistance to me. After reviewing the info presented I thought it warranted pulling the assembly apart again and taking a second look. After getting the swing arm off I tried pushing the spindle through both bushes with the swing arm out of the cradle,when checking for fit initially I had just done each side individually. Turns out the spindle fouls when trying to push past both bushes, verdict... a twisted swing arm. I'm pretty disappointed at this stage, I had the frame straightened and brackets and thread etc fixed but seems as though they missed the fact that the swing arm was twisted, I didn't think to check it was true. So now after getting everything powder coated I think I'm going to have to strip the powder coat, have the swing arm straightened and then re powder coat it. Unless of course anyone has a better idea, I was thinking of trying to straighten the swing arm without any heat but doubt its a good idea. Here are a few photos, one looking down the bore of the bush with the spindle pushed through the other side and one of the swing arm on a flat piece of ply wood.

1 3/8 spindle updat and more questions


1 3/8 spindle updat and more questions
 
Hi Morton,

Sorry to hear that, but better you find out now.

Was the bike involved in an accident?

In some of your earlier pice it looks as though there are hammer marks on the cross tube? Perhaps somebody has tried to straighten it before?

I think the first thing you need to do is find out where exactly it's twisted. Put the swing arm spindle in one side and slide it over until it touched the other bush. Then put the wheel splindle in or a similarly sized rod or wood dowel ( obviously check them for straightness first). Then a rod between the shock mounts. Then you have visual points of reference, and you can work out by measuring what exactly is bent. Have you run a straight edge along the top and bottom of each arm?

In the picture on the plywood, are both axle plates sitting on the wood ?

If both the arms are straight, it's possibly twisted at the weak point between the gussets on the cross tube, in which case (in my opinion) it should be possible using a press to re-align them without much damage to the powder coat.


Cheers,

cliffa
 
Powdercoat will not take any direct pressure or direct heat but it is flexible enough to take some bending before cracking if bending cold.

You were able to bend the swingarm enough on your first assembly with the spindle, you may just need to overbend by the same amount to get the 2 bushes in line as long as the rest is already in line.

The powdercoater will remove any old coating by blasting before reapplying new so leave it on until its straight.
 
Hi Cliffa,
yes my old man laid it down at speed back in the day, apparantly it dug in and flipped a few times, the bike sat in the shed my whole childhood unfixed until he donated all the bits to me recently. I knew the main frame was bent but didn't know about the swing arm. Both axel plates are flat in that photo, I'm fairly certain it is bent at the gusseted section. I have eye balled the arms and both look straight and I put straight edges in a few spots to try and work it out. That's a good suggestion to check for alignment though and I'm going to do exactly what you have suggested to check where its bent. Good eyes too, I had not even noticed the dents in the gusset, but your right it does look like someone has put a hammer into it in the past. And cheers Kommando I wasn't sure if the powder coat could be lifted by blasting it but that's good to know, I think your onto it too that if it bent enough to get the spindle through once I should theoretically be able to do it again and keep it there. I'm going try and bend it cold to realign once I confirm where it is bent. Cliffa i was thinking of clamping the cross tube in a vice with soft jaws and trying to force the legs in opposing directions to "untwist" it, I'm a little worried it may bend the arms though rather than untwist it at the gusset, how would you use a press to achieve the same result?
 
Hi Morton,
I think until you know where it's bent, it's difficult to advise. As you have three points in contact with the board may mean the cross tube is bent, so if you do as you are suggesting ( which I'm not knocking) you may get the front aligned, but then the spindle holes are out, and the wheel is cocked. Are you sure that board is really flat? If it's not it could send you in the wrong direction.

So basically everything that is correct needs to be held in place on an engineers table, and the bit that is out of kilter pressed. Personally I would take it back to your frame straightener ask them for a quote, then consider buying a new one if the costs are close, or maybe somebody on here has a spare?

Who knows, it may have come out of the factory like that :roll:

Cheers,

cliffa
 
Thanks for the post. I wouldn't have been aware enough to look at the bushing/spindle alignment while removing the swingarm spindle, but because of your post, I looked down the bore to check the alignment. It's perfect and is that mother stuck. The dent is from the 3 pound sledge missing it's mark.
1 3/8 spindle updat and more questions
 
morton said:
Thanks all for the feedback to my last post its all of great assistance to me. After reviewing the info presented I thought it warranted pulling the assembly apart again and taking a second look. After getting the swing arm off I tried pushing the spindle through both bushes with the swing arm out of the cradle,when checking for fit initially I had just done each side individually. Turns out the spindle fouls when trying to push past both bushes, verdict... a twisted swing arm. I'm pretty disappointed at this stage, I had the frame straightened and brackets and thread etc fixed but seems as though they missed the fact that the swing arm was twisted, I didn't think to check it was true. So now after getting everything powder coated I think I'm going to have to strip the powder coat, have the swing arm straightened and then re powder coat it. Unless of course anyone has a better idea, I was thinking of trying to straighten the swing arm without any heat but doubt its a good idea. Here are a few photos, one looking down the bore of the bush with the spindle pushed through the other side and one of the swing arm on a flat piece of ply wood.

1 3/8 spindle updat and more questions


1 3/8 spindle updat and more questions

Easy to fix.
 
Easy to fix, how so? I took part of cliffas advise and gave the frame straightening guru a call today he's out of town for the nest fortnight so I'm stalled at the moment. Also glad some other people are benefiting from this post as this site has been incredibly helpful to me
 
The bend seems to be between the eye of the bush holding and the cross beam as the cross beam looks to have the same gap across the table from one side to the other, as long as the 2 axle holders are both touching then you can grip the cross beam in a vice and press the eye down (or the axle inserted into the eye) just past the ref of the table level and it should relax back into position, a sliding pin will confirm.
 
Figured i would finish the tale of the twisted swing arm. ended up taking it back to the frame guru out my way, he was able to untwist the swing arm for me without ruining my powder coat which was great. When asked about his technique he said he put the spindle through the bushes and clamped it in position and pretty much used a crow bar through the axel slot to put it back into shape. Not particularly scientific but it worked. I mocked everything up tonight and its all lining up petty nicely and now ive finally got something which rolls and resembles a motorcycle, very exciting!
1 3/8 spindle updat and more questions
 
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