I can’t believe it..

Andy J

Andy J

Hero member
Location
Isle of Man
Was working on one of the 500 twins today with the intention of getting it ready to ride at the weekend. When I bought it, it came with some very old tyres fitted, so I just rode the bike accordingly and didn’t lean it over too much and whack the throttle open wide. My 350 is currently awaiting some attention, so I decided, as it has some relatively young tyres, to do a wheel swap. Having removed the 350 wheels I then traveled with them to my other lock-up to do the switch.
First problem was undoing the wheel nuts. I’ve no idea who the last person was that did them up, but I’m surprised the bearings didn’t squash. The wheel spindles also took a bit of persuading to pull out, but when I went to refit the rear wheel I couldn’t get the spindle back all the way through and initially couldn’t understand why, everything seemed to be lined up correctly. After a bit of experimentation I then discovered one of the holes on one of the chain adjusters wasn’t sufficiently round and was binding on the spindle. A few strokes of a file solved that issue.
I then moved onto the front wheel. I drove the wheel spindle out and expected the front wheel to just drop down. It didn’t, it just remained in place. I was rather baffled by this. Thinking the brake pads may have just stuck to the discs I gave the wheel a bit of a yank but it wasn’t playing. So why not remove the callipers. Because a previous owner had replaced the Caliper bolts with some shiny but soft cap heads that are so tight they won’t budge and the heads are going to get rounded off if not removed carefully. So knock out the pads and it still won’t drop out. On closer inspection I observe the outside of the disc, on both sides, is hard up against the side of the slot in the caliper. How the hell anyone fitted them like that is difficult to fathom. Assuming it’s possibly an issue with the discs I try fitting the other wheel, but it’s exactly the same, so it’s a problem with the forks or callipers, as the wheel that came out the 500 fitted straight into the 350 forks and callipers.
Therefore, it doesn’t look like I will be riding it this weekend. 😤
 
I’m leaning on the issue being, the stuck front wheel is actually a triple front wheel, not a 350/500 wheel. Whacked in (perhaps literally) by someone who didn’t know the difference.
 
chrisk said:
I’m leaning on the issue being, the stuck front wheel is actually a triple front wheel, not a 350/500 wheel. Whacked in (perhaps literally) by someone who didn’t know the difference.
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I’m not sure about that Chris as the wheel fitted okay into the 350 with the discs central in the callipers. I’m also going to have a look at the spacers on the 500, and when I can get the callipers off the 500 I will see if a different pair makes any difference.
 
A triple front wheel won't fit the 500 forks Chris, not even with a bloody big hammer! Pretty difficult to make up for 20(30?)mm difference!

Sounds more like bent stanchions, as well as a bunch of other horrors.

piet
 
Without pictures it sounds like you’ve got mismatched components, but if the disc rotors are tight against the calipers, how did the brake pads come out?
Some pics would explain things better. What is the stamping on the rims and calipers?
 
before you all get too deep into thought, let us all remember this is the Manx Mog we are dealing with here, so normal parameters may not be apropriate.
CLEM
 
sfcpiet said:
A triple front wheel won't fit the 500 forks Chris, not even with a bloody big hammer! Pretty difficult to make up for 20(30?)mm difference!

Sounds more like bent stanchions, as well as a bunch of other horrors.

piet
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Yes that’s already at the back of my mind Piet. The bike is an ex race bike, in addition to starting out life in 1978 as Slater’s F500 demo bike, so a fairly important bike in the development of the Montjuic.
 
I finally found time to have another go at fitting the replacement wheel today. Firstly, I ground the heads off the stupid cap heads, and lo and behold the remaining ‘studs’, that wouldn’t budge previously, virtually came out by finger twisting alone.
The wheel went back in okay and rotated freely without the brake callipers fitted. I offered up the callipers and they appeared to align correctly with the discs so I fitted them loosely to start, and checked the wheel was still rotating freely, which it did.
I then tightened up the hex head bolts, and although the discs and callipers continued to look like they were correctly aligned, the wheel now wouldn’t rotate without force. Slackening the bolts a bit did allow rotation again but there is definitely a bit of a distortion somewhere as the wheel becomes tighter in one particular spot during rotation. Further investigation clearly needed, plus a calliper rebuild I reckon, which might not be such a bad idea as one pin was like a banana, and in fact broke as I tried to refit it for the purposes of testing the brake alignment. The other pin doesn’t look in too good a condition either…. However, it will have to wait until after I get back from the Willersley event.
I then moved on to another ‘Five minute job’ on a different bike that, an hour or so later, I gave up on and went home…
 
Probably wrong as well but check the internal bearing spacer and external wheel spacers are steel and not alloy
 
If the calipers bind when tightening their fixing bolts, there's either an alignment problem or the pistons are seized in the calipers, or both.
The latter seems more likely to me, so I'd suggest you proceed with the caliper rebuild.
If it's an alignment issue then you may need to fit shims between the calipers and fork mounting lugs.

The reason I think it's not caliper alignment is because if the pistons are free to move, even a mis-aligned caliper shouldn't bind. The pistons will simply be pushed into the calipers as you tighten their bolts. That's assuming the alignment isn't so far off that the caliper housing is contacting the disk. If that was the case you'd have noticed it. It would need to be several mm off for that to happen.
 
First thing I'd do would be force the pads/pistons back into the calipers. If they don't retract a rebuild is obligatory. If they do retract, then refit them and tighten them. If the wheel binds it has to be caliper contact with the forks - which is an alignment issue.
 
OK. Maybe we need some clarification. I thought you were referring to the caliper bolts, but Vince is talking about the axle nut, and he's offered good advice about ensuring the internal bearing spacer is present and correct.

The calipers are normally fixed to the fork legs with high tensile socket head (Allen head) bolts. Your description of "hex head" is a little ambiguous. It doesn't match the normal caliper bolts or the axle nut.
 
Dellortoman said:
OK. Maybe we need some clarification. I thought you were referring to the caliper bolts, but Vince is talking about the axle nut, and he's offered good advice about ensuring the internal bearing spacer is present and correct.

The calipers are normally fixed to the fork legs with high tensile socket head (Allen head) bolts. Your description of "hex head" is a little ambiguous. It doesn't match the normal caliper bolts or the axle nut.
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Std bolts for calipers are 17mm M10 hex heads (as in not an allen head). The two halves of the calipers are held together by allen head bolts.
 
Ok contraversy time, I have Stainless Alan bolts holding the adaptor and the 4 spot callipers to my Cerani frontend and they have been there for years. They're pretty thick, I very much doubt they are going to fail in Shear Force or Bending Moment.
 
piranha-bro2 said:
Std bolts for calipers are 17mm M10 hex heads (as in not an allen head). The two halves of the calipers are held together by allen head bolts.
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As we're talking 500 here, mounts are M8 on the stock 05 calipers. :) Not entirely sure, but I do think they used Allen bolts, don't have a parts list to hand atm.

If the calipers are properly centred over the discs once the wheel is fitted, it is most probably a siezed caliper piston causing the binding. The stock chromed steel pistons like to corrode (after 40 years, they all are...) and should be replaced with the later anodised alloy items.

piet
 
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