Author Topic: Centre-Stand Modification - Locking the Spindle  (Read 1596 times)

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GBT

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on: September 02, 2021, 02:51:31 pm

The topic of centre-stands has already been well-aired in Tech Tips recently:
https://forum.classicmotorworks.com/index.php?topic=31398.0

Following on from this, I thought I would take the opportunity to post some pictures in this section showing a modification I carried out to the centre-stand on my Euro IV Classic C5. The idea was to prevent possible problems in the future by installing a locking pin through the centre-stand spindle to stop it rotating in its mounting holes and wearing them out.

On my C5, and all the EFI models as far as I am aware, the centre-stand spindle fits inside two 16mm diameter mounting holes machined into steel plates welded to the frame. The spindle is held in position by a split pin (cotter pin) and washer at each end, but it is not locked in any way, and seems to be free to rotate backwards and forwards in its mounting holes whenever the stand is operated. As the frame plates are only 5mm thick, the grinding motion of the spindle in the holes can eventually cause the holes to become elongated. This then causes the stand to go too far over centre, and the rider finds it difficult to retract the stand; the bike wants to slide forwards and has to be lifted to get it back over the centre position.

This centre-stand design appears to be common to both the EFI models and the iron-barrel Bullets. On the iron-barrel models the spindle mounting holes are in the rear engine plates. These plates are listed as spare parts, and could therefore be replaced if necessary. On the EFI models, however, elongated mounting holes would probably need to be welded since they are an integral part of the frame.
(See 00306c.jpg)

In order to prevent the spindle from rotating in its mounting holes I decided to install a locking pin. I found that the shank of a four-inch (100mm) vine eye was just the right diameter to fit into one of the split pin (cotter pin) holes in the spindle. I bought a pack of five vine eyes from an online supplier, and gave my wife the other four to use in the garden. My parts list also contained an M6 x 25mm hex setscrew (fully-threaded hex bolt) and nyloc nut, two 6mm large o.d. washers, one 6mm plain washer and a short length of 1/4" bore thick-wall PVC fuel hose.
(See 01592a.jpg)

The vine eye has a woodscrew threaded portion at one end which I cut off, leaving a plain shank. The M6 setscrew will fit through a bush fitted into the eye at the other end. I happened to have some 1/4" bore thick-wall PVC tubing (fuel pipe) which was just the right o.d., about 1/2", so I cut off a 5mm length and inserted it into the eye. The M6 setscrew will go through this bush and through a new 6mm hole in the frame plate.
(See 00397b.jpg)

I inserted the new locking pin into the split pin hole on the left-hand end of the spindle, with the original large washer still in place, and lined it up against the frame plate to determine where to drill the 6mm hole. The photo should show that the plain shank of the vine eye is long enough to pass right through the split pin hole to the edge of the large washer.
(See 00392a.jpg)

I then drilled the 6mm diameter hole through the frame plate, being careful to keep clear of any welds on the inside of the plate.
(See 00417a.jpg)

The M6 hex setscrew was then inserted through the bush, with a large o.d. washer on either side, and through the new hole in the frame plate. I secured it with a nyloc nut and washer on the other side of the plate, so that the vine eye/locking pin was firmly attached to the frame plate, thus preventing any rotation of the spindle and hopefully any elongation of the mounting holes.
(See 01014b.jpg)
(See 01587a.jpg)

Note: The last three images will follow separately.


GBT

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Reply #1 on: September 02, 2021, 02:54:10 pm
Last three pictures!


gizzo

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Reply #2 on: September 03, 2021, 12:26:17 am
That's a good idea. Thanks for sharing it.  8)
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Bilgemaster

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Reply #3 on: September 03, 2021, 12:42:18 am
Indeed! That ain't a bad notion for some slopey circumstances, huh?
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Narada

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Reply #4 on: September 03, 2021, 04:14:55 pm
Nice work GBT! Very "clean" and great picture documentation!  :)

If you don't mind, just for clarity, I have a couple of questions.

Is the idea that the rotation of the shaft is causing wear while the bike is being lifted up onto center stand, and while lowering down? (I am usually sitting with all my weight on bike as it lowers, is this bad?  :P ) Or is the idea to prevent constant vibrational friction while riding?  ???

Is the 6mm bolt with nyloc nut tightened down securely? If so, is the purpose of the bushing just to fill the void in the vine eye? Or, is the idea to leave the 6mm bolt just lightly tightened so that vine eye can freely move during vibration or center stand engagement?  ???

Just curious, and hoping for a sure understanding of this mod. FWIW, the center stand on my 2015 C5 seems fine so far (10,000 miles on bike), and I use it a lot.

I will be doing a major service on mine later this month and I'll have a look at those holes to see how mine's holding up then.  ::)
« Last Edit: September 03, 2021, 04:43:24 pm by Narada »
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GBT

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Reply #5 on: September 04, 2021, 12:25:57 pm
Nice work GBT! Very "clean" and great picture documentation!  :)

If you don't mind, just for clarity, I have a couple of questions.

Is the idea that the rotation of the shaft is causing wear while the bike is being lifted up onto center stand, and while lowering down? (I am usually sitting with all my weight on bike as it lowers, is this bad?  :P ) Or is the idea to prevent constant vibrational friction while riding?  ???

Is the 6mm bolt with nyloc nut tightened down securely? If so, is the purpose of the bushing just to fill the void in the vine eye? Or, is the idea to leave the 6mm bolt just lightly tightened so that vine eye can freely move during vibration or center stand engagement?  ???

Just curious, and hoping for a sure understanding of this mod. FWIW, the center stand on my 2015 C5 seems fine so far (10,000 miles on bike), and I use it a lot.

I will be doing a major service on mine later this month and I'll have a look at those holes to see how mine's holding up then.  ::)

Thanks for your comments.

Regarding your questions:

1. My main concern was that the shaft (or spindle as RE call it) would rotate in its mounting holes in the frame and cause wear whenever the stand was being operated, both lifting the bike on to the stand and lowering it again. Since the stock retention system allows the spindle to rotate freely, it seems to me that the spindle would probably prefer to take the easy option and rotate in its mounting holes, which are only 5mm in depth (the thickness of the frame plates) rather than remain static in its mounting holes while the stand pivoted around it. There will be more frictional forces between stand and spindle than between spindle and frame mounting holes. The surface area is probably greater, but that's just my theory.

Added to which, as you say, if the rider is also sitting on the bike when the stand is being lowered, that would (forgive me) inevitably create more pressure on the stand pivot points and exacerbate the problem. I realise that many riders prefer to lower the stand while sitting astride the bike, and I think I can understand why. When I started motorcycling nearly sixty years ago, motorbikes were lighter in weight and I just learned to retract my bike's centre-stand while standing to the side of the bike and guiding the stand back up with my right foot. But I was younger and fitter then, motorcycles have become far heavier, even the Bullet/Classic is heavier than it used to be a few years ago, and I am noticing these things more now.
I don't think what you are doing is wrong. I would never suggest that. If your method gives you more confidence, that's all that matters. The last thing you need is to try my method and end up with the bike falling over. I have to admit that when I lower my C5 down on to its wheels I am more conscious of the bike's weight, and I don't think I could hold it if it fell away from me.

Which makes me wonder why RE don't beef up the centre-stand pivot mechanism on their bikes and provide proper bearings or lubricated bushings to take account of the extra weight, knowing that many riders prefer to operate their centre-stands in the way you have described.
The centre-stand has always been a rather neglected component, hasn't it? So neglected in fact that many manufacturers today don't even bother to fit one at all.

Your theory of vibrational friction is one I never thought about. You are ahead of me there, but maybe the tension of the two springs holds the spindle and stand tightly in place while riding?

2. Regarding the 6mm retaining bolt, yes it is tightened securely. The inner diameter of the vine eye is 12mm and my bushing, made from 1/4" bore fuel hose, measured about 1/2" o.d., so when I pressed it into position it shrank slightly in size and the M6 bolt just fitted nicely through the bushing with no play. As you suggest, the purpose of the bushing is simply to fill the void and prevent the locking pin rocking a few degrees back and forth during stand operation. I cut the bushing to a length of 5mm. The diameter of the vine eye shank is 4.3mm so that when the nyloc nut is tightened down, the two large o.d. washers will clamp the bushing and prevent any movement of the locking pin.

I hope you find your centre-stand in good condition after 10,000 miles. Maybe what I have done is over-kill, but the reason I carried out this mod was that when I got my new C5 last year and lifted it on to its stand I noticed that the rear tyre was almost brushing the ground.
(See IMG_01055aa.jpg)

I felt the need to do something with the stand as there should have been more clearance than that, and I could foresee possible problems ahead. The picture shows a brand-new C5 Euro IV standing on a level concrete floor. It's evident that any pivot wear and sloppiness in the centre-stand is likely to drop the rear tyre right back on to the ground and make it impossible to rotate the wheel.

When RE changed the front wheel size on the Classic EFI models from 18" to 19" in 2012 they didn't appear to change the centre-stand at the same time. I could be wrong, but there only seems to be one part number (801580) listed for all the C5 models, regardless of front wheel size. Unless I'm missing something obvious, fitting the larger front wheel would have lifted the front wheel spindle by about 1/2" and dropped the rear by a similar amount with the bike on its stand. So why RE didn't specify a longer stand is anyone's guess. The stand on my bike is just a bit too short.

RE did fit the new in-line front forks at around the same time as the front wheel change, so that might be relevant I suppose, but the new forks would need to be 1/2" shorter than the earlier forks to compensate for the change to the 19" front wheel, and now things are getting complicated.

Thanks again for your comments.


Silverback

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Reply #6 on: September 09, 2021, 11:13:51 pm
could idea to prevent future issue.

thanks for  the detailed post. excellent!
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