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Author Topic: Reliant Disc brake conversion  (Read 237254 times)
terry t
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« Reply #360 on: October 22, 2015, 06:59:28 AM »

continued from F/S,
also again from memory. there were two types of pads ite the thinner ones. I sure there was a write up on here listing various parts?
I will see if I still have the boxes in the calliper set up I have on the shelf
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Olds
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« Reply #361 on: October 22, 2015, 07:11:19 AM »

Yep Terry. Been reading through and it looks like there are two pad thicknesses 15 and 17.5mm. Ones needed are 15mm according to previous posts.
« Last Edit: October 22, 2015, 07:17:45 AM by Olds » Logged

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terry t
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« Reply #362 on: October 22, 2015, 07:19:09 AM »

Getting back to the disc not sitting true.
Was the centre part of the hub machined smaller.or the centre hole in the disc machined larger?
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Hadfield_mike
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« Reply #363 on: October 22, 2015, 08:07:33 AM »

I had the hub machined to fit the disc.  The remaining shoulder on the hub isn't much after it's opened up to 60mm dia so had it chamfered to match the inner edge of the disc.  It was a machine shop that done it and they measured the chamfer to make sure it matches perfectly.  Off the shaft it sits perfectly flat but that's when it's laid flat on the floor.  The issue is when it's in situ it doesn't seem to line up as well.  I can get it lined up better by using the wheel nuts to adjust it but that's not something I want to rely on when it comes to fitting the wheel too.
At the moment there's nothing to secure the disc to the hub other than the wheel nuts so I'm wondering if drilling and tapping it for a flush fit bolt would help, after aligning it using the wheel nuts.
The hub on the other side needed a press to release it but the side in question just popped right off with a gear puller and literally a few taps with a rubber mallet, nothing that would cause the shaft to bend.  All I can think of is that it's dropped a bit as I've held the disc up to the hub and that's pulled it out of alignment before I've nipped the wheel nuts up.  I'll try using the wheel tonight as at least that has the chamfered holes to match the wheel nuts and seems to line up ok with the 4" PCD.
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terry t
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« Reply #364 on: October 22, 2015, 08:27:05 AM »

There only held on by the wheel don't know any one that's drilled and bolted them on. once the wheels are on the disc arnt going any were
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Olds
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« Reply #365 on: October 22, 2015, 08:28:55 AM »

If you can 'adjust it ' using the wheel nuts, then it is not sitting flush with the hub face to start off with.
Sounds like the face has not been machined flat. Put a known straight edge across the face to check.
Or the chamfer on the hub is touching the chamfer on the disc slightly. The chamfer on the disc is not meant to be a locating point. It is there to provide clearance for the small radius at the base of the hub spigot and can vary in size from one manufacturer to another, or even between discs from the same manufacturer.
« Last Edit: October 22, 2015, 08:39:06 AM by Olds » Logged

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Hadfield_mike
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« Reply #366 on: October 22, 2015, 07:13:36 PM »

I suspect I might have to machine the hubs again. Just measured with a DTI. the hub face without disc on is +/-0.2mm which I'm comfortable with. That was as close to the outside as I could get without fouling on the wheel studs. Same exercise with the discs on and it's +/-1.8mm. I can't leave it at that. It's too much for the brake carriers and will catch on the pads. Not sure what an acceptable tolerance is but 1.8mm seems too high to me. Back to the machine shop I think. Gutted I paid the lad £40 to machine those hubs too.
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Manky Monkey
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« Reply #367 on: October 22, 2015, 07:51:38 PM »

You mentioned drilling the hub for a securing bolt. I did exactly that on mine, using an existing hole on the disc & a countersunk headed allen bolt.
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terry t
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« Reply #368 on: October 22, 2015, 08:16:26 PM »

Is that the outer 4 corners of the hub to fit inside the disc tight?
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Olds
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« Reply #369 on: October 23, 2015, 06:04:40 AM »

Good point Terry. Check the across corners dimension of the hubs and compare with the diameter of the machined mating surface inside the disc.
Disc runout should be less than 0.15mm ( RDA EBC suggested maximum)
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Hadfield_mike
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« Reply #370 on: October 23, 2015, 08:38:11 AM »

The hub run out was 0.2mm which would obviously be compounded with the larger dia of the disc but even with that it couldn't have been the hub that was making the disc alignment so far out.  I've just noticed the sides of the hub are raised slightly.  It's not a lot but certainly enough to prevent the disc sitting flat to the hub.  Possibly from gear puller used to remove the hub.  The inner section is flat and true as that's been machined so if I sort out the outer part then the disc will sit flat on the hub as it should.
The next issue will be reducing that 0.2mm misalignment but maybe a bit of a rub down of the end of the half shaft will soft that as it's a bit rough on the surface, not bad but worth a clean for a better fit maybe.
The outer 4 corners are fine though, they fit in nicely with a touch of clearance.
I've heard drilling a brake disc is very difficult.  Is that a job that can be done with a hand drill?  Struggling for workshop type tools in my pokey little garage.
I may have bitten off more than I can chew with this being my first project but I've started so I'll finish.....
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terry t
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« Reply #371 on: October 23, 2015, 09:34:52 AM »

Just clean the burrs up with a file or grinding disc if you haven't got the tools just have the wheel hold the disc even if you spend time drilling it and tapping it. it won't make it any more efficient when braking? it just holds it in place while your fitting the wheel  

Can you post a photo of the hubs and disc so we can see whats been machined?
« Last Edit: October 23, 2015, 09:38:28 AM by terry t » Logged
Olds
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« Reply #372 on: October 23, 2015, 09:38:25 AM »

Ah. If the hub flange has distorted The studs should be removed and the whole contact surface machined or at least any raised areas filed flat.
It is quite common for the flange on these hubs to distort while being pulled off the taper.
Not sure why you need to drill the disc.
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Getting older but no wiser! Just using bigger hammers.
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spanners
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« Reply #373 on: October 23, 2015, 09:39:40 AM »

brake discs drill suprisingly easy,, quite soft material really,,
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Hadfield_mike
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« Reply #374 on: October 26, 2015, 11:27:42 AM »

I suspect it's the face of the hub that's causing my alignment issues.  I turn the half shaft with nothing on it using a DTI and it's spot on, barely a flicker of the needle and so slight I can't even see the movement enough to measure it.  When I fit the hub and put the clock gauge to the machined face it's way out.  Obviously even worse with the disc on.  It seems the gear puller I used has pulled too much on the hub and bent it (I suspect).

The machine shop done the face for me but only to open up the centre part to allow the 60mm centre hole of the disc to fit.  The studs weren't removed for this so it was literally just enough to make the 60mm disc centre fit over and done with a parting tool as that's pretty much all that would fit in with the studs present.
I'm taking the hubs and half shafts to the machine shop today to get the full face machined with the half shaft attached and the studs removed.  By doing it this way I'll be getting a true face of the hub machined from the shaft itself.  I am also going to ask them to drill a couple of countersunk bolts in so once the disc is lined up and checked it can be secured tight to the hub.  To save removing and refitting the hub once lined up, I'll get the mounting bracket slipped over after the machining but before final check that the disc is running true.  At least then I'll know I'm bringing home a perfectly lined up half shaft, bracket, hub and disc and I don't need to disturb any of that to refit to the trike.  Fingers crossed.
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