Minimum Recommended Caliper/wheel Clearance?

[johnnyboy666 195 1 Cars]

just wondering what people's opinions are on this? I had to grind a slight bit off my new calipers to fit the wheel on, and was going to give it another going over, as it looks tight, but is there a general rule of thumb for clearance? or just keep an eye on it?

cheers

John

[joshsnoad 2]

Clearance is so it doesn't touch the the wheel! As long as it isn't scrapping you are fine.

[Cameron 16]

I'd make sure you have at least a couple of mm, but the only way to tell for sure is to go for a drive and see if it touches.

[johnnyboy666 195 1 Cars]

Oh aye yeah they don't touch, ive done plenty of road test miles on them already. just didn't know if calipers swell or shift over time or anything

[dcc 855]

There shouldnt be any movement in your calipers or your wheel. I had a set of s16 brakes which i managed to get to fit under pepperpots using an angle grinder. Was a bit close to say the least didnt rub though

[johnnyboy666 195 1 Cars]

Cool, I'll give the grinder a break then in that case

These are only 1.6gti calipers, but the mounting face of the steelies is very flat, so isn't very caliper friendly!

[calvinhorse 870]

Just double check as the pads wear down the caliper can't move across any more.

 

If the inner pad wears then it could slide over.

 

Just a thought I may be wrong!

[Tom Fenton 1,526]

As the pads wear the caliper moves away from the wheel, but worth making sure that there is enough clearance to allow brand new full width pads to fit!

[johnnyboy666 195 1 Cars]

yeah, I thought that it would move that way, but when I thought about it, it makes sense that it would move away from the wheel.

I put brand new pads in when I put the new discs and calipers on, thought I'd refresh everything at the same time. (and the old pads were eaten by the sticky caliper)

[oonip 4]

Your mad taking an angle grinder to your calipers!

 

A brake kit from A P Racing is designed with a minimum of 3mm wheel clearance, although this is mostly to take up the large variation you will see in uprights / bearing packs etc. As previously said, if it doesn't touch then it will be fine.

 

But grinding a caliper really? I hate wheel spacers but I'd rather see that than cowboy grinding!

[Batfink 201]

Cowboy depends on how much material you take off

[stef205 91 1 Cars]

Ahem!

But this was milled instead

[EdCherry 34 1 Cars]

Milled... looks like it was chewed by a dog!

 

Nice of you to add such a feature for it to fail upon.

[stef205 91 1 Cars]

[Cameron 16]

EEK! Is that.. really yours? If so I would go take a few mm off that with a radiused cutter, as what you've done there is put a massive stress raiser on the most highly loaded section of an aluminium part. That nice big fillet (radiused corner) is was there for a very good reason!

Edited May 9, 2013 by Cameron

[dcc 855]

smooth it, taper it and polish it ftw

[oonip 4]

Cowboy depends on how much material you take off

 

Have to disagree, by taking any material off the caliper your effectively saying you know the stress in that part and you know that by removing material the caliper will not fail in your application.

 

Sure there are worse places to remove material than others but ultimately your playing fire by taking an angle grinder to a brake caliper.

 

 

 

EEK! Is that.. really yours? If so I would go take a few mm off that with a radiused cutter, as what you've done there is put a massive stress raiser on the most highly loaded section of an aluminium part. That nice big fillet (radiused corner) is was there for a very good reason!

 

Actually that area is not that stressed as the upright stiffness gives the caliper masses of support, granted its a stinking great 'crack here' feature!

[Cameron 16]

As the only point the caliper attaches to the upright, I'd say it was definitely stressed.

[oonip 4]

What I actually said was that that area of the caliper is not that stressed, so responding by saying 'that's where it mounts to the upright, it's obviously stressed duuurrr', is plain stupid.

 

Of course it's stressed, my point was to clarify the false information that you previously posted about it being the most highly loaded part of the caliper, it is not.

[EdCherry 34 1 Cars]

And the most highly stressed part of the caliper is...

[oonip 4]

For opposed piston calipers the highest loaded area is generally the inside of the caliper 'bridge' (the bit that goes over the disc), as you can imagine the pressure in the bores on the outside of the caliper are trying to push away from the disc, and on the outer side of the caliper there is no support as it sits over the disc. So the caliper bridge has to cope with all of that force. On top of that there's a torque being applied by the pads driving into the caliper, again on the outside of the caliper there's no support so the whole thing tries to twist.

 

The highest stressed part of a caliper depends on design, but it's usually the caliper bridge as it has to fit within a wheel so space is often limited.

[Cameron 16]

Ok..

 

What generates some of the highest loads on a vehicle? The front brakes.

What is the load path? Caliper body (brake torque) into front upright.

What transfers the brake torque from the caliper body into the upright? The mount - in this case, the part that had it's nice large fillet turned into a nice sharp milled corner.

 

Case closed.

[oonip 4]

What about caliper pressure? Does that go into the upright?

 

The mount is two seperate bolted joints transmitting the loads to the upright, the material between the two mounting holes does not see a great deal of load.

 

I do still agree he's weakened the caliper, just not at its most loaded point!

[johnnyboy666 195 1 Cars]

*fetches popcorn*

[Cameron 16]

Caliper pressure is irrelevant, as the bridge is unmodified. If you want to be a pedant then by all means keep arguing about where the most stressed part of a caliper is, but I won't listen to you as it's a pointless diversion.

 

Your two mounting holes are supported by the upright in that they don't get squeezed together / pulled apart, yes, but that isn't the point I'm making. The fact is that the mounting lugs are what react all of the forces / moments from braking (forgetting about clamp load) and stop the caliper from just rotating round with the brake disc; whether it'll fail or not I don't know, but adding a big stress raiser in to an area that has been designed to have a nice large fillet radius is just asking for trouble.