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Discussion Starter · #1 ·
been trying out the rear caliper on the back and came across another issue!

So, this is how the caliper would sit, which is perfect, with the slot cut there where I can just weld a tab on the frame for it to slide..



but now I've come across this problem...
first, I can't use the wheel adjusters on the inside, as on the right side, as there's no space for it once the caliper is there (pic after this one):



secondly, if I push the wheel as far forward as it can go, so I assume all is straight, the frame plate doesn't seem to sit parallel to the caliper bit? meaning if I get a spacer in there it won't sit flush with the plate?



or is it a case of making a spacer that a bit of clearance and once all tighten it will be fine?

and, as I can't use the wheel adjusters on the inside, I'll have to cut the little tubing off the inside and weld a new one on the outside, but can't find anything like this adjuster?
Took the pic at the hayride, I also guess these adjusters would slot into the plate?



Thanks!
JP
 

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JP,
it looks like ya have the caliper plumded to the mc, use the mc to put presure on the caliper piston, this should "center" the bracket and line it up with the adjuster plates, if not ya have problems.
On the chain adjusters, it looks like you will have room between the bracket and frame, all you will need to do is bend the bolt (off set) to clear the caliper bracket and line up with the tube it goes into (____/----).
 

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I think assuming everything is straight is part of the problem. You said in another thread that the hardtail was welded on professionally. Did you double check to make sure it was straight? And, even if it is, the ends of the axle slots may not be perfectly across from each other.

After you've double checked the hardtail, start with the wheel about centered in the slots and center the wheel straight in the frame. Check the chain alignment. You can always space it farther out, but if you have to go in a little, there are dished sprockets you could put on backwards, so the teeth are farther in, then space that accordingly.

After all that, you can center the caliper on the rotor. Little D's method will work, or if you're not plumbed and bled already, you can push the caliper pistons back in as far as they'll go and use equal thickness shims between the pads and the rotor.

Looks like you'll need a spacer between the caliper and the hub and another between the caliper and the frame. That second one doesn't have to be just a simple spacer. You could make the thickness correct at the axle, and leave enough material at the back to weld a bolt that will line up with the existing chain adjuster tube. No need to move the adjusters to the outside. (Which might cause you to need a longer axle.)
 

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Did you setup wheels using string method?
As mentioned,I dont think you can use the axle slots to ensure parallelism.
I would get the wheels true to each other and go from there.


Is your rear sprocket registered in the wheel pilot?
It looks like a large spacer behind it?
Is this a common mod?
Im sure its been done, just not sure i would trust the concentricity of the loose 7/16" bolts unless they had a tight shoulder or countersunk.
 

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Discussion Starter · #5 ·
Right! thanks all for your replies, let me see if I can answer all of it..

sorry for all the very noob questions :(
this is my first build, im keen on doing it, but have no one near that knows this kind of stuff, so all the help i get is from the internet, once again thanks for taking the time to reply...

JP,
it looks like ya have the caliper plumded to the mc, use the mc to put presure on the caliper piston, this should "center" the bracket and line it up with the adjuster plates, if not ya have problems.
On the chain adjusters, it looks like you will have room between the bracket and frame, all you will need to do is bend the bolt (off set) to clear the caliper bracket and line up with the tube it goes into (____/----).
Nothing is connect on the bike, but I see what you mean. I could use the air compressor to push the pistons out and "clamp" the disc, that way the caliper would be centered on the disc and at the same time be on the correct place along the axle.

that's what you meant wasnt it? I hope.. lol
So far I've done it by eye centering the caliper, as the compressor is a 150L industrial and im not working on the bike anymore today, so would be a waste starting it now..

About the chain adjuster and the space, I think its not possible to do what you say, as there's no room even to run a bolt there, once I move the axle a bit more backwards, half of the caliper bracket is on the way of the adjuster...

Just took this pic to show what I mean..



and looking at it now, it actually doesnt seem like the axle plate is far off from being parallel with the caliper bracket?
But then again.... the axle might not be straight as it should, one side further in than the other and the parallelism is out the window.. lol

I think assuming everything is straight is part of the problem. You said in another thread that the hardtail was welded on professionally. Did you double check to make sure it was straight? And, even if it is, the ends of the axle slots may not be perfectly across from each other.
Very good point, I just assumed it was properly done as it's a custom shop who done it...
How would I go about checking its properly done? is there reference points to take measurements from?

After you've double checked the hardtail, start with the wheel about centered in the slots and center the wheel straight in the frame. Check the chain alignment. You can always space it farther out, but if you have to go in a little, there are dished sprockets you could put on backwards, so the teeth are farther in, then space that accordingly.
I understand what you say here... basically, wheel centered with the seat post/tank/headstock and then check if rear and front sprocket are aligned... right?

if they are not use the 2 methods you explain...

what's the best way to check sprocket alignment?
Last time I've done it was push the axle as far forward as it can go, I assumed both slots would just be the same and therefore everything would be dead straight and then put a flat bar on the rear sprocket and checked if it was sitting flush with the front sprocket..

is that right?

the rest of your reply (ref caliper pistons and adjusters, I replied above to little d

Did you setup wheels using string method?
As mentioned,I dont think you can use the axle slots to ensure parallelism.
I would get the wheels true to each other and go from there.

Is your rear sprocket registered in the wheel pilot?
It looks like a large spacer behind it?
Is this a common mod?
Im sure its been done, just not sure i would trust the concentricity of the loose 7/16" bolts unless they had a tight shoulder or countersunk.
I havent setup the front wheel yet, I have a set of springers on the front, I guess would be a case of measuring the distance between the legs and center the wheel right in the middle is that correct?

no, there's no spacer behind it, its just he hub.
The sprocket sits flush with the hub...

So, you guys see what im working on, here's a pic of the bike



thanks to all for the time taken to reply, its really appreciated!
 

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Discussion Starter · #6 ·
Hi,

any tips on making sure everything is straight? how to make sure the sprockets are aligned, etc?

I'm pretty much sorted with the spacers and the external wheel adjusters and how to get it done... just got a longer axle, £25 delivered, its 16" long, I only need it to be 13 to 14", so I can get it machined to suit..

now im just stuck on how to make sure all is straight before I dive deep into the rest..

thanks!
 

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To get the sprockets lined up, I use a straight edge from sprocket to sprocket.
To line up the rear wheel, I use two 8' florecent light bulbs. Rubber band them to the wheel, past the front and adjust untill paralel.
Oh ya, great idea about using air to compress piston, never thought about that, will from now on.
 

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Discussion Starter · #8 ·
little d, can you explain better the florecent light method? or do you have a pic? I've read it about 10 times and im trying to picture it in my head, but no luck! dont really understand....

yeh, the air compressor is a good way.
I use it most of the time to renew calipers in old landrovers....for example, if you have a 4 piston caliper, you lock 3 pistons (with a socket between 2 and clamp on 3rd), get the air in and make the 4th piston pop.
Clean, new seals, etc... pop piston back in. then clamp that one and another 2 and make other pop out and so on...

like this:

 

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Discussion Starter · #10 ·
thanks for that! I keep forgeting about YouTube and how there's so many how-to videos in there!
I guess taking ref points from the original frame should be ok?



I'll use that method, but will have to take measurement points from the seat frame or any other part of the original frame as my front wheel is not in place with spacers yet...

but that method will be good to figure out where the front wheel has to sit and what spacers I'll need for it.

thanks!
JP
 

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For the left adjuster:
Can't you weld a tab, or if not set up to weld aluminum, grind flat and tap a couple holes and countersink bolts and a tab to the m/c axle bracket for the adjuster to push against?
 

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Chevelle,
thanks for posting the vid, way easyer than trying to type it out. Like ya said, they are straight edges so you can use anything that is straight and long enough.
JP,
if ya don't have your frontend on ya can use dowel rod or tubeing but it has to fit snugly in your neck and be long enough to reach the floor.
ps. ya gotta get the sprockets lined up first.
 

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A cheap laser like a picture hanging laser is a great tool. Line up both sprokets. If the wheel has to be off center alittle its ok, as long as chain is tracking and wheels are aligned to the front. My bikes have all been offset alittlw and still track great. My chop is 1/4 offset and will track strait all day. its because of the rear drum ... Your final positon is as center ass you can be and tightened down with sprockets lined up. We shine the laser from under the sprockets and get a full line all the way down the profile of both sprockets from the rear. The great thing about the wheels you use is dished and flat sprockets and spacers are available so between that and truing for offset you should be able to get real close .
 

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Discussion Starter · #14 ·
littled, I have the front end on (there's a pic of my bike a bit further up), what I meant was the front end is not setup yet, as in the front wheel is just on the axle, dont have the spacers yet to make it sit dead center on the forks
 

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I use the parting line (where the caliper halves are put together) to center on the rotor then cut spacers accordingly. You will need to modify that lower tube to add a tab for the caliper to ride on. peace
 

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Discussion Starter · #16 ·
ha... good tip! I'll keep that one in mind.

yeh, the tab won't be difficult to do, just weld on the frame. how thick though? about 5mm?
 
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