The Marengo "Loki" Thread.

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Try loosen both bolts
clamp caliper to rotor ,
Tighten bolts ,
spin and check.
Check rotor does not move sideways when brake applied .
If it does redo the above .

Regards Emma
IS what I have been doing basically Emma. :D
 
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Clamp and tighten works with single pots assuming you've set the non piston side correctly first. I'd have thought 2 or 4 pots would need to be mounted so that the caliper gap straddled the rotor as evenly as possible. If that is achieved than any drag will be because one or both pistons are not withdrawing as designed and the caliper may need a rebuild or it could be as simple as the spring between the pads is defective. The other alternative is that the caliper body is catching the rotor.
 
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Clamp and tighten works with single pots assuming you've set the non piston side correctly first. I'd have thought 2 or 4 pots would need to be mounted so that the caliper gap straddled the rotor as evenly as possible. If that is achieved than any drag will be because one or both pistons are not withdrawing as designed and the caliper may need a rebuild or it could be as simple as the spring between the pads is defective. The other alternative is that the caliper body is catching the rotor.
Yes, understood, this may be why at least one of them is rotating freely (a good set-up procedure was followed). The other one? Not sure what it is yet, more work needed. :D
Sometimes I think discs are far more trouble than they are worth.
 
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Ok lets have another go ?

discs are meant to move [ bend ] otherwise single pot calipers won't work ?
when you are welding the mounting on you clamp the caliper up to grip the disc ?
the mount is 3/8" or 1/4" so the mount is NOT going to bend !!
when you tack the mount on the welds will shrink
so what happens next ?
if you are unlucky this pulls the disc from out of true with the frame ?
you continue to weld up the mount and it is then not parallel with the disc ?

there is no way any amount of clamping and bolting the caliper up will correct this problem

now on a commercial trike jig built you expect the mount to be in the correct place ?

would you expect the same from a mount attached by a Zombie in a shed ? [ don't ask me how I know this :rolleyes: and I only had 1 to weld on !!]
 

Twinkle

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The caliper body bolts can be shimmed and a feeler be inserted on the " dead side " of the caliper . This should help . The other opportunity is under braking the rotor grows slightly and may touch the caliper body.
 
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The caliper body bolts can be shimmed and a feeler be inserted on the " dead side " of the caliper .
Yes

However you would only look at that as a solution IF you were first looking for the caliper mount and the disc not being parallel.

What I am saying is no amount of clamping it up with the brake lever and screwing it up tight will fix it if the mount is in the wrong place !
 
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Update 10th Jan 2020:
Added a small lead wrap around the stem of the schrader valve on the LH wheel to promote "drop to the bottom" behaviour and to demonstrate free running.
Here is the video:
So that shows the LH hub is fine and the brakes are not binding in any way.

Then the right was tried (same M.O.) and no dice. Quick to stop and random stopping points.
Here is the hub with caliper and with the same lead weight added to the schrader valve stem.

Quite a difference. I also tried it with the caliper removed and it still stops at random points around the rim. So there is a bind internally in the hub-bearings I think.
I took the caliper to bits and "correction", it is single pot. So I removed the pads and the spring and jacked the piston out as far as I dared and washed it all with car brake cleaner and gave it a seeing-too with a fine wire brush.
I then played in-out games with the piston with the brake lever and a pair of pliers on the caliper/piston ...back & forth.
I have bent the pad-spring out slightly to increase its return-pressure and re-assembled the caliper on the bike.
I stopped then because it was getting very cold and a visitor had arrived.
Tomorrow I will set it up exactly the same as the L.H. Caliper and that will be as good as it gets I think.
 
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Dan

Excellent , I assume before you re-install the caliper you will be investigating the drag ?

Or are they bearings you don't have ' instock ' ?

Mind you that is exactly the same behaviour I have with one of my SA brakes and I did not get to the bottom of it :-(
 
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Dan

Excellent , I assume before you re-install the caliper you will be investigating the drag ?

Or are they bearings you don't have ' instock ' ?

Mind you that is exactly the same behaviour I have with one of my SA brakes and I did not get to the bottom of it :-(
Paul,
Just edited my earlier post, with the footage of the wheel W/O caliper mounted and showing the random stopping points (long & boring vid TBH).
But at least I can remount the caliper tomorrow and set it up properly with a slip of paper between the static pad and the rotor and try again.
 
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A couple of suggestions:

1. Place a marker line around each face of the disc to see if it gets scratched during rotation.

2. Remove the disc and check rotation without it. Probably the quickest route to where the problem is.

Seeing there is a certain randomness to the problem, I would suspect bearings.
 
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Hey aren't we missing a trick here ?

Isn't there and almost identical electric model also sat on the premises ?

So a simple wheel swap will get you on your way ?

not sure how you can judge an unused trike as good to go with this fault ?
 
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Hey aren't we missing a trick here ?

Isn't there and almost identical electric model also sat on the premises ?

So a simple wheel swap will get you on your way ?

not sure how you can judge an unused trike as good to go with this fault ?
Yes, there is, but I am loath to start messing with it and possibly end up with no usable trike at all.
I shall persevere with fixing this one for now.
 
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Update 11th Jan 2020
Fixed it! :D
I spent some time trying to get a perfect alignment on the caliper to rotor relationship but it was just not working right.
The "Ticking" noise of the spun wheel led me to the conclusion that the rotor tips were striking the caliper and the caliper position needed to be slightly further away from the rotor to prevent this.
I placed Stainless Steel M6 washers between the caliper and the caliper mounting bracket.
I also played some more with the caliper itself and I can now absolutely confirm it is a double piston caliper (for goodness sake, make your mind up man!).
Here is a video of the remounted caliper and the spinning wheel. It seems perfectly OK to me now.

 
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well done that man..

that would have plagued you every pedal stroke !

now we need some miles on it...
 
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I placed Stainless Steel M6 washers between the caliper and the caliper mounting bracket.
What only 2 washers ?

The Python front has 2 under one bolt and 3 under the other IIRC
 
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Rear mudguard + fittings ordered (I don't want a muddy-stripe thank you).
 
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