Pandemonium Brembo adapter challenges - Non metric hardware?

GeorgeOC

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Hello all, I would love to know if anyone has crossed this bridge. Some may have seen in my build thread that I am converting a 76' C fork over to a Brembo caliper set up, attempting to use the Pandemonium caliper adapter. I went ahead and found a caliper on ebay...

I have run into a tiny snag. The issue that I have run into is that it looks like the hardware supplied with the adapter is not metric. The caliper thread is 10x1.25. I am unable to thread the adapter mounting bolts into the threaded caliper holes.

Is it possible that the caliper mounting locations should not be threaded at all? I think that if the bore ought to be smooth, I might be on track.

Am I crazy if I were to find a proper machine shop to mill those out?
 

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Hmmm...I could be all wet here George but I wonder if you have the incorrect thread series - ie. a fine (rather than a coarse) metric thread.

Except for specialized threads such as tapered pipe threads (aka NPT) that are used in low pressure fluid sealing applications such as domestic water plumbing connections, nearly all metric AND inch thread series come in both coarse and fine pitch variants. Coarse threads are much more common, but fine threads are stronger and so they are often used in safety-critical applications such as brake systems. Fine and coarse threads - even if they're the same diameter - are NOT interchangeable.

Given that the caliper is European-made, it seems unlikely that it uses an inch thread series. In fact, about the only place in the world that still uses inch-series threads is the US (and particularly Harley-Davidson). Even the American auto industry went metric many years ago.

Anyhow, I suggest that you have a careful look at the thread depth and pitch (how far from one thread to the next along the axis of the thread) on the male and female parts before you start re-tapping any holes.

Pete
 
BTW - I believe that an M10x1.25 is a fine thread and so perhaps your fasteners are incorrect.
 
Hello all, I would love to know if anyone has crossed this bridge. Some may have seen in my build thread that I am converting a 76' C fork over to a Brembo caliper set up, attempting to use the Pandemonium caliper adapter. I went ahead and found a caliper on ebay...

I have run into a tiny snag. The issue that I have run into is that it looks like the hardware supplied with the adapter is not metric. The caliper thread is 10x1.25. I am unable to thread the adapter mounting bolts into the threaded caliper holes.

Is it possible that the caliper mounting locations should not be threaded at all? I think that if the bore ought to be smooth, I might be on track.

Am I crazy if I were to find a proper machine shop to mill those out?
The mounting ears on the Brembo caliper where there are threads. Become a through-hole. It needs to be drilled out. Did you receive your instructions when you purchase this kit? You can call me at the shop anytime 419-576-6812
 
ahhhh - gotcha. Interesting.

Too bad the kit is presently out of stock....
 
Pete................................if you enjoy making things, you could make your own adapter bracket for a Brembo caliper. I made mine from 3/8" aluminum. There are pictures in my Gallery (album).
 
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I had the bracket from Dan and also purchased the brembo caliper from him. The difference for me was that the caliper mountings holes were not threaded. Whether it came that way or Dan bored them out I can't say, but they weren't threaded.
 
The mounting ears on the Brembo caliper where there are threads. Become a through-hole. It needs to be drilled out. Did you receive your instructions when you purchase this kit? You can call me at the shop anytime 419-576-6812

Happy Dan, gggGary, Thank you. Ah-ha moment achieved. Thanks guys! The adapter didnt have instructions, but gggGary pointed be towards the video. The caliper I bought was actually miss-shipped as a left side, not the right. So waiting on that to complete the fitment test. Of course I thought I might as well just see if I could go with the left side setup, but the seller already is sending the replacement.

Thanks again guys!
 
The mounting ears on the Brembo caliper where there are threads. Become a through-hole. It needs to be drilled out. Did you receive your instructions when you purchase this kit? You can call me at the shop anytime 419-576-6812

I installed one of these kits a few years back alongside a Mikes rotor, and yeah if memory serves me right you drill out the caliper threads.

But in hindsight I'm wondering why that is? Why drill out the threads on an existing caliper in order to use imperial hardware? Couldn't the kit ship with the plate tapped with matching metric M10 fine so you thread right through? Would there be issues with threads potentially not aligning?
 
The design by Pandemonium is such that the caliper is bolted to the adapter plate. In order for the alinement of the caliper and disc to be correct, they want the caliper to be clamped tight to the adapter plate. Yes, if the caliper was threaded, the threads may not aline and you could end up with a gap between the caliper and adapter.
Whenever you bolt any 2 pieces of metal together, you only thread one piece, so that the other piece with a hole only, will be pulled tight with no gap.
 
The design by Pandemonium is such that the caliper is bolted to the adapter plate. In order for the alinement of the caliper and disc to be correct, they want the caliper to be clamped tight to the adapter plate. Yes, if the caliper was threaded, the threads may not aline and you could end up with a gap between the caliper and adapter.
Whenever you bolt any 2 pieces of metal together, you only thread one piece, so that the other piece with a hole only, will be pulled tight with no gap.

Makes sense. Cheers RG
 
The design by Pandemonium is such that the caliper is bolted to the adapter plate. In order for the alinement of the caliper and disc to be correct, they want the caliper to be clamped tight to the adapter plate. Yes, if the caliper was threaded, the threads may not aline and you could end up with a gap between the caliper and adapter.

Whenever you bolt any 2 pieces of metal together, you only thread one piece, so that the other piece with a hole only, will be pulled tight with no gap.

RtGent is precisely correct here - and this is one of the most important things to realise about threaded fasteners. You cannot thread two things on the same fastener (unless its a locknut type set-up in which case you must tighten the two parts against each other to secure them). Such a design is what engineers refer to as over-constrained and if you try something like that - you are doomed to have an unreliable joint. Think of it like a 4-legged stool - you can NEVER get all four legs to sit on the floor with exactly the same load on each and so the stool will always rock a little - whereas a 3-legged stool will always be stable.

The other key thing about threaded fasteners is that for them to work properly, the fastener (bolt, stud, etc.) must be loaded only in tension (i.e. forces along the length of the screw or bolt) and never in shear (forces at right angles to the axis). A tension-loaded fastener will squeeze the two parts being joined hard enough to cause sufficient friction between them - to resist any shear loads.

Imagine for example, that you installed a brake disc on a wheel and you did not tighten up the bolts beyond finger-tight. There would be little or no friction between the disc and the wheel hub - and so applying the brakes would cause those bolts to be loaded in shear to resist the braking forces (and they would almost certainly simply bust off with disastrous results). Alternatively, if you torque the disk mounting bolts up tight, they will squeeze the disc and hub together hard enough that there will be sufficient friction between them to resist the braking torque - and the bolts won't even "know" that you are applying the brakes.

THAT is why highly loaded critical fasteners such as brake caliper and disc mounting bolts, cylinder head studs etc. - must be torqued to a specific value (usually measured in ft-lb, in-lb, N-m or kg-m). That is done partly to keep them from coming loose, but mainly to ensure that enough friction is created to resist shear forces or, in the case of cylinder head studs, the axial fatigue loads caused by internal combustion pressure. The other reason for specific torque values and tightening patterns in bolt or stud groupings (such as the wheel studs and bolts or the studs on something like a cylinder head for example) is to ensure that all of the fasteners are tightened to the same degree and thus, the frictional forces are spread evenly across the available surface area and no single fastener is over-loaded and that the parts being joined are evenly loaded with no gaps for internal pressures to escape.

So guys:
1) buy yourself a good torque wrench and an accurate set of sockets (I like the "click-type" torque wrenches);
2) check out the proper torque in the manual and set the wrench to that value;
3) follow the tightening patterns in the manual to the letter.
.....and all should be well as you "screw around" with your bikes.

Cheers,

Pete
 
Thanks everyone for their comments here. I pitched this question to Dan, but thought i'd check around a little further in the mean time. So my ebay seller sent me a left caliper on accident... The correct right side is not available. Would it be of any consequence to mount the brake on the left for this project?

What think I have going for me is:
- Dan's adapter plate can be used on either side
- 34mm forks in this case have the caliper mounts high enough on the leg to clear any speedometer mech or cable.

Dont see any reason why I cant do this:
 

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....neither do I - in principle it should be fine.

...But - how about a dual disc set-up....
 
GeorgeOC........................yes you can install a left caliper on your front wheel. In fact that is exactly what I did on my 78SE.
When I decided to go the Brembo route, I was unable to find a single "right" caliper, so I bought a pair, left and right.
I installed the left on my front wheel and the right on my rear wheel. Needless to say, I now have amazing braking capabilities, which is what I prefer, as I'm big on safety.

You and I have different years and different forks, so I don't know if you might have minor alinement issues with respect to the caliper and disc.

Pete................that was a super explanation of bolting techniques and use of proper torque....................its a bonus for this site to have an
automotive engineer as a member.
Brembo front mounting.JPG Brembo Rear Mounting.JPG
 
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Max................that was a super explanation of bolting techniques and use of proper torque....................its a bonus for this site to have an
automotive engineer as a member.
View attachment 92166 View attachment 92167[/QUOTE]

My pleasure...and while I don't really mind at all, my name is Pete and not Max. Max comes from a nickname "MAXimum PETE" - which I had in my earlier years due to my tendency to go at things whole-hog...
Cheers,
Pete
PS - I really like that brake set-up on your SE. It must pop your eyeballs out when you drop anchor....! ;)
 
RtGent is precisely correct here - and this is one of the most important things to realise about threaded fasteners. You cannot thread two things on the same fastener (unless its a locknut type set-up in which case you must tighten the two parts against each other to secure them). Such a design is what engineers refer to as over-constrained and if you try something like that - you are doomed to have an unreliable joint. Think of it like a 4-legged stool - you can NEVER get all four legs to sit on the floor with exactly the same load on each and so the stool will always rock a little - whereas a 3-legged stool will always be stable.

The other key thing about threaded fasteners is that for them to work properly, the fastener (bolt, stud, etc.) must be loaded only in tension (i.e. forces along the length of the screw or bolt) and never in shear (forces at right angles to the axis). A tension-loaded fastener will squeeze the two parts being joined hard enough to cause sufficient friction between them - to resist any shear loads.

Imagine for example, that you installed a brake disc on a wheel and you did not tighten up the bolts beyond finger-tight. There would be little or no friction between the disc and the wheel hub - and so applying the brakes would cause those bolts to be loaded in shear to resist the braking forces (and they would almost certainly simply bust off with disastrous results). Alternatively, if you torque the disk mounting bolts up tight, they will squeeze the disc and hub together hard enough that there will be sufficient friction between them to resist the braking torque - and the bolts won't even "know" that you are applying the brakes.

THAT is why highly loaded critical fasteners such as brake caliper and disc mounting bolts, cylinder head studs etc. - must be torqued to a specific value (usually measured in ft-lb, in-lb, N-m or kg-m). That is done partly to keep them from coming loose, but mainly to ensure that enough friction is created to resist shear forces or, in the case of cylinder head studs, the axial fatigue loads caused by internal combustion pressure. The other reason for specific torque values and tightening patterns in bolt or stud groupings (such as the wheel studs and bolts or the studs on something like a cylinder head for example) is to ensure that all of the fasteners are tightened to the same degree and thus, the frictional forces are spread evenly across the available surface area and no single fastener is over-loaded and that the parts being joined are evenly loaded with no gaps for internal pressures to escape.

So guys:
1) buy yourself a good torque wrench and an accurate set of sockets (I like the "click-type" torque wrenches);
2) check out the proper torque in the manual and set the wrench to that value;
3) follow the tightening patterns in the manual to the letter.
.....and all should be well as you "screw around" with your bikes.

Cheers,

Pete

Outstanding answer! Thumbs up.
 
You're most welcome! I don't want to bore people - but if you ever have a question along those lines, please fire it in. I have been an engineer in industry and a Mech & Auto Eng'g prof for 36 years and mechanical design and stuff like that is my thing. I have always found that it is easier to work on stuff if you really understand how it works.

Beside, guys like RetiredGent, 5Twins, Grizld and all the other real 650 experts on this site have already taught me a heck of a lot - and I pick up more useful tidbits everyday. Thats what makes these sites so interesting, fun and useful!

Pete

PS - and I also agree: Beer is Good!
 
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