Dual Disc Caliper Alignment Issue (not the usual) PART 1

[Ewan 500 K1]

Bit of a funny one when setting up my dual discs. The caliper arm for the additional disc on the right hand (speedo drive Side) was perfectly aligned with the disc without any need to mess around with shims or files contrary to all expectation (photo one) (later ... of course this is wrong , as identified by oddjob, while it's true  that caliper arm shoud be parallel in vertical and horizontal planes with the disc, it should not be flush with the disc.. it should be offset a couple of mm to the outside of the disc), but the original set up on the left hand side is misaligned (second photo) and had to be brought into line by putting some washers in between the caliper arm and the fork.... see photos 3 & 4 and close ups in next post. Anyone got any idea whats gone wrong ? . I have changed the wheel from the original.. maybe its that , see two posts down

[Ewan 500 K1]

Close Ups

1. Left side (usual side for standard single disc) from front
2. Left side from rear
3. Right side (side with aditional disc) from front
4. Right side from rear

[Ewan 500 K1]

1) Last time the bike was on the road , it had a single disc and ran fine with that. At that point it had 550k3 forks on and presumably 550 hub and axle

2) it still has the 550k3 forks but I used a different hub to build a new wheel. The replacment hub has the "flats" on it for the speedo drive . See pictures 1 & 2 for the old and new hubs

3) photo 3 shows the old and new axles and photo 4 shows the new axle with adapted speedo drive plate... adpated so that it has lugs to fit onto the "flats" on the hub.

Are the surprising results from setting up the brake caliper likely to have anything to do with changing the wheel / axle set up. If not ... any other ideas out there ? ....... and .. does it matter anyway when I now have both calipers aligned with the discs anyway ?

[Bryanj]

Oddjob, speedo drive plate is same as far as thickness goes on both early 750 (needed for twin disc to drive off the flats) and later type driven by two ears under a chrome cover.

I have pictures of the early one in a "how to" in word format added but forgot to put in it if its a 500 you need the 550 slider to replace the 500 one with no mountings

The twin flat hub lasted till late in the 70's to the best of my memory.

[Ewan 500 K1]

oddjob, bryan ... thanks for interventions. Please be patient with me 

Attached photo of original and modified speedo drive plate which was modifie from one exactly the same as the original. I think the confusion may have comefrom the fact that the picture of the speedo drive on the axle , in above post, also showed the spacer from the left side of the spindle up against the speedo drive plate ... ie it had slipped along the spindle

[Ewan 500 K1]

The new hub came from my basket case 500 four with frame number 2120447, though not sure if that will be the bike's original wheel. I've been out measuring and comparing the old and new hub. The new nub (with the speedo drive flats) is 9mm narrower than the old one .. as measured between the flat disc mounting surfaces (measurement D in attached diagram). Presumably that is what is throwing things out ... but ... as long as I get the calipers aligned correctly to the discs it wont matter a hoot (will it !!! ?? ).

[Ewan 500 K1]

Said this before Ewan but you've got this wrong. You say the R/H side is aligned but it isn't. The inner brake pad is the one that needs to be perfectly flat with the disc not the outer one, you cannot really gauge whether it's in line without the caliper being in place, think of this logically, if the caliper were fitted as you have it the rear pad would sit at an angle to the disc, both pads would then wear at the same angle, you'd end up with crap brakes until they both wore to match the disc.

thanks oddjob , see exactly what you are saying now... the caliper end needs to be parallel to the disc in the vertical and horicontal plane .. but NOT FLUSH as in my photo above

[Ewan 500 K1]

As I had a hub with flats I thought I'd go the way outlined in Bryan's doc attached in his post above .. seemed better than drilling holes in the hub and using rivets ... but I never realised that this hub I have is narrower than the standard 500 hub !

The 500 speedo drive plate is the one on the right, (in the pictures in reply #5) the dished one with the 2 ears

They're both 500 speedo drive plates, the one on the left started off the same as the one on the right .. I just took a grinder to it and then bent over two tabs to fit into the cut aways on the new hub (ie the hub in the second picture in reply #2) . I think that the new hub with the cut aways for the speedo drive plate is what was used on the 450K3 and 750K0.  The  motogrid parts diagram quotes part number 44641-300-000 for the speedo drive plate for these models, although it appears to show the wrong part in the drawing. It should look like the one in the first attached picture in this reply , second picture in this repy shows it installed. So presumably my new hub is actually off one of those two models despite me getting it off my 500 basket case.

the 500 didn't have  what appears to be a collar behind the speedo plate on Ewans picture (4th picture in reply #2), this appears to be extending down the spindle and looks at first glance to be part of the speedo drive plate, however after Ewan has posted the pic it's clear it's not so is this collar part of the speedo drive itself or something that Ewans fitted ?, don't think it's part of the spindle unless the angle the pic was taken at is confusing the issue.

 
The collar in the picture is actually the spacer (part number 44301-425-870) from the left side of the spindle set up, its not connected to the speedo drive plate or the spindle ... its just slipped down the spindle before I took the photo, so it can be ignored, apologies for confusion caused

As for the hub Ewan, yeah 9mm thinner would make sense as regards to where the discs are sitting in relation to the caliper arms, yeah if you could get the calipers perfectly aligned then it wouldn't matter BUT why go to all that trouble? replace the hub with a bog standard 500 hub and you'll get the L/H caliper perfectly aligned after and once you see how that should align it's a lot easier to visualise how the new R/H caliper needs to be mounted.

I rebuilt the new wheel with new spokes and rim on the 450K3/750K0 hub with the speedo drive flats on it and modified the speed drive plate to suit that hub, so I quite fancy seeing if I can finish the job using that hub, rather than rebuilding another wheel.

I think what I need to do is:
1. On the right hand side  .. see third and fourth pictures attached to this reply. I need to change this set up so that the caliper arm moves outward a bit relative to the disc by aabout a couple of mm, possibly by:
a) moving the muguard stay so that it is on top of the caliper pivot arm top bracket instead of between the bracket and the fork leg
b) shaving a bit off the bottom flat on caliper arm pivot where it bolts to the fork .

2. On the left hand side   Move the caliper arm inwards by a few mm relative to the disc, either by
a) using shims between the caliper arm pivot mounts and the fork (as in the 3rd picture in the first post in this thread and the 1st and 2nd pictures in the reply #2 in this thread)  AND/OR ..
b) make up a ring spacer to go between the disc and the hub, to bring the disc out from the hub a bit

I'll see how it goes when I start rebuilding once the frame is powdercoated ... if its all too much of a pain in the arse I might take you up on the hub offer and start over again 

I think you've finally got what I was trying to point out, it's the inside caliper pad which because it's a fixed pad that needs to be perfectly flat to the disc, the outside movable pad then moves to take up the clearance. .

Yep , I think I've got it too... its all seems dead obvious now !!!, dunno what I was thinking about before

To adapt the original 500 speedo drive plate all you need to do is to grind off the dish part with the 2 ears on, go down to almost the flat part of the plate, I used valve grinding paste and a piece of glass to get the rest of the dish off and ensure it was perfectly level. All you do then is to fit it into the speedo drive, fit the spindle through it and then fit the spindle through the wheel bearings, that aligns the drive plate up with the hub, as you've cut off the ears you now need to ensure it's centrally located and this way does it. Hold the plate tight against the hub and remove the spindle and speedo drive, I then used 2 knock rivets out of an RD400 steering lock to hold it onto the hub, you'll need 2 holes drilling into the plate and hub and once it's properly aligned as above you secure the plate to the hub with the rivets. Quick spin of the wheel with the speedo drive in place and check to see everything is not oscillating and jobs done.

Yep, have seen that mentioned as the alternative to what I've been trying ... but you explain it really well here 

GL1000 disc bolts are ideal for mounting the twin discs as they are the correct length.

Yep, part number 90122-371-000...they are discontinued and Dave Silvers doesnt have any. I eventualy  managed to get some good clean second hand ones of those from this fellow: http://www.wingovations.com/ 

Many many thanks again for your comments oddjob... its really helping me get my head round it all

[Ewan 500 K1]

An alternative suggestion from CrazyP on US forum for the left hand side, to what I was planning in the above post:
Reduce the length of the spacer on the left (nut) side of the spindle by 4 to 6mm , to bring the left hand caliper into line with the left hand disc (ie instead of shimming out the caliper bracket and/or making up a spacer to go between the hub and the disc).
The spindle nut may not then screw fully up to meet the shortened spacer, so would need to tap the spincle to make the threa for the nut longer ? Also it would only bring the bottom of the fork in a bit ... but the top would stil be in same place as dictated by the triple T clamp .. so doesnt really seem ideal ? This would result in the forks flexing inwards slightly .. would this matter ?

[Bryanj]

Ewan, the hub with two flats is the standard 500 hub same as 450 and 750, the hub without came along a lot later mate so somebody has been mix-n-matching prior to you!!!

[Bryanj]

Yup I'm certain as the Honda drive plate with the bent ears, as used on very erly ones, needed the two flats to drive off. The only reason i can think of for not lining up is if the forks changed when the hub did and/or something is fitted not quite far enough/too far/wrong place

[Ewan 500 K1]

acording to motogrid parts diagrams all three 500 models :

CB500 A MOTORCYCLE, JPN, VIN# CB500-1000001
CB500K1 A MOTORCYCLE, JPN, VIN# CB500-2000001
CB500K2 A MOTORCYCLE, JPN, VIN# CB500-2100001

share the same part number for :

Axle Collar (44311-371-980)
Axle (44301-425-870)
Bottom Yolk (53200-323-020B)
Speedo Drive Plate (44641-341-000)
Front Hub (44601-300-040)
but the front forks change from 51500-323-305 (left) and 51400-323-305 (right) to 51500-323-315 and 51400-323-315 at the introdction of the K1

But .. in my original CB500 / CB500K1 parts book the hub stays the same (44601-300-040) for both models but the speedo drive plate changes from 44641-300-020 to 44641-341-000. The speedo drive plate with the tangs for the hub mentioned in Brians document (44601-300-000) with the cut away flats is only for the 450K3 and 7750K0 according to motogrid.

CMSNL notes in the K1 parts list that the speedo drive plate 44641-300-020 is superceeded by  44641-341-000.  CMSNL also has the sme hub (44601-300-040) listed across all 500 models up to the K3 and the picture shown has the cut away flats on it on all models

I'm lost ! ... this may be a road to ..... I'll just bodge on and see what I can do to make everything line up .. almost finished getting the right hand side done bby putting the mudguard bracket on top of the caliper arm bracket instead of between the bracket and the fork , and taking about 2mm off the flat on the bottom of the caliper bracket pin... looks like I need to take a bit more off the pin.

[Ewan 500 K1]

the caliper arm pin top bracket changes at introduction of the K1 ... maybe thats the key difference that allows the narrower hub to be used

[Bryanj]

The forks change at the K1 as all the internals change and you no longer have the long threaded rod that screws into the damper at one end and the top nut at the other.

The top caliper piece superceeds to the later number so that fits all of them.

Are you sure the wheel bearing with screwed collar is all the way in to the shoulder as that would make a difference?

[Ewan 500 K1]

Are you sure the wheel bearing with screwed collar is all the way in to the shoulder as that would make a difference?

yep, bearing fully in.... but , eh but ... might have some developments tomorrow that might make my face red.. cue the wife chasing me about with the rolling pin for spending an inordinate amount of hours in the shed wasting time