Random disk brake question unrelated to MJs

[DirtyComanche]

This is random.

 

What's the largest solid (non-vented) brake rotor you've ever seen?

 

Have you ever seen a solid brake rotor on a car/truck/van/whatever with an 8 lug axle (8x6.5 pref)?

 

Scratching my head trying to come up with something close to fitting on something odd without going to a rotor and caliper that weighs way more than it needs to.

[gogmorgo]

Not sure what exactly you're planning, but I'm not sure you'd want something big enough to require 8-lug rotors to be stopping without adequate heat evacuation. Unless the odd thing you've got only needs to stop once and has time to completely cool down again.

When I worked at partsource, the biggest solid rotors I remember seeing were I think for a Grand Caravan. But then I wasn't really keeping an eye out for them. I don't remember seeing 8-lugs without vents though.

[DirtyComanche]

Trying to make budget 'race' parts.

 

The typical brake swap for a full float axle is to use K-20 calipers and rotors.  Both are overkill.  So guys split the rotor and and run a smaller caliper, either from Wilwood, or a Toyota type of application (there's a few out there that can fit).  It's a bit of a drag to do, but it does work.  Otherwise,  Explorer rear rotors actually will fit on an 8x6.5 hub, but it's marginal.  The hat diameter is the issue, you have to grind a fair amount of the head off the studs in order to get them through.  There is another way to do it, which would be to counterbore the hub and install the studs into it, and then bolt the rotor to the back of the hub rather than using the studs to retain it.  Or you could do what GM did on the K-truck stuff and window the hat so there's clearance for the heads of the studs.  But just weighing options and seeing if there's something easier.  It isn't like the Explorer rotor is a terribly convenient starting point.

 

Looking up the Grand Caravan ones, they're only about 1/4" larger in diameter than the Explorer ones, and given they're the same bolt pattern I'm not sure if the hat will be any larger.  Unless there's an option I didn't try.

 

I think a 6 lug application might be a bit better starting point if one exists.  The Isuzu Trooper rotor is rather small though, otherwise it could have been a good candidate.

[gogmorgo]

My experience with race parts is that generally speaking off-the-shelf components for other non-race vehicles seldom provide what you're looking for, unfortunately. But you probably already knew that. My team had custom rotors turned, solid with a whole bunch of cross-drilling, I think just from grey cast. Hope you find something that works for you, though.

[Pete M]

how does the explorer rear rotor compare to other rear disk applications?  are explorer parts bigger than ZJ or KJ rotors?  what's a modern 1/2 ton pickup running these days?

[HOrnbrod]

how does the explorer rear rotor compare to other rear disk applications?  are explorer parts bigger than ZJ or KJ rotors?  what's a modern 1/2 ton pickup running these days?

 

I have Explorer rear disks on my truck. For comparison purposes, the rotor is 11" in diameter and 1/2" thick (vented).

[DirtyComanche]

 

how does the explorer rear rotor compare to other rear disk applications?  are explorer parts bigger than ZJ or KJ rotors?  what's a modern 1/2 ton pickup running these days?

 

I have Explorer rear disks on my truck. For comparison purposes, the rotor is 11" in diameter and 1/2" thick (vented).

 

 

Shouldn't be vented...  Unless you've bought fancy aftermarket instead of 'normal' stock style.  Or do you mean drilled/slotted?  Official numbers in the book at 11.25" and .470" thick, or something like that (nobody really agrees, I think it's because it's actually listed in metric and converted/rounded).

 

A modern vented rotor is typically about 11-13" and 1.25-1.5" thick.  There is exceptions, as there is some thin vented rotors on cars like the Lincoln Mark VIII, Mustang, etc (some are even 5x4.5 bolt pattern if you're interested).  And there's some much bigger stuff used in front applications.  There's probably smaller stuff used in front applications off of cars, but the question would be finding something with a hat large enough to accept redrilling/fit over the hub.

 

The GM rotor that normally is used in this application is 12.8" and 1.28" thick.  1/3 of the thickness is mostly void space (no weight) as it is the vent area.  Guys cut them in half at the vents, then turn the (previously vent are) face smooth.  We dug up some rotors for a limo that are about .790" thick and 12.8" diameter, waiting for them to arrive to be weighed.  I have my doubts that they're any lighter, as most of what has happened is the vent area is smaller, and they have a thicker hat to incorporate a parking brake drum.  The K20 rotors most guys use are a front rotor, and they actually windowed the hat for whatever reason (airflow probably), so between that and the wider vent I doubt it weighs more.

 

The small Isuzu rotor is only 10.3" diameter, or something like that, IIRC.  Super small friction area, as the hat is the same size or larger than the comparable solid rotors.  It actually would probably be a good choice if a guy was running 6 lug hubs.

 

In short I doubt there is anything that exists that's really worth the hassle.  The conclusion I am at right now is to not worry about it.  I'm waiting for other ideas on hubs that don't cost a fortune, we're going to try weighing some and see what we can come up with.

[Rockfrog]

Explorer rears are pretty much the same as TJ and ZJ, and likely KJ (liberty) rears. The calipers are the same between them, pads differ only slightly, but rotor size is the same.

The rear brakes on my XJ consist of ZJ brackets, TJ calipers and rotors and Explorer pads. All on my 8.25.

 

Rotors are a solid rotor with brake drum inside hat.

 

Sent from my SGH-I337M using Tapatalk

[HOrnbrod]

 

 

how does the explorer rear rotor compare to other rear disk applications?  are explorer parts bigger than ZJ or KJ rotors?  what's a modern 1/2 ton pickup running these days?

 

I have Explorer rear disks on my truck. For comparison purposes, the rotor is 11" in diameter and 1/2" thick (vented).

 

 

Shouldn't be vented...  Unless you've bought fancy aftermarket instead of 'normal' stock style.  Or do you mean drilled/slotted?  Official numbers in the book at 11.25" and .470" thick, or something like that (nobody really agrees, I think it's because it's actually listed in metric and converted/rounded).

 

A modern vented rotor is typically about 11-13" and 1.25-1.5" thick.  There is exceptions, as there is some thin vented rotors on cars like the Lincoln Mark VIII, Mustang, etc (some are even 5x4.5 bolt pattern if you're interested).  And there's some much bigger stuff used in front applications.  There's probably smaller stuff used in front applications off of cars, but the question would be finding something with a hat large enough to accept redrilling/fit over the hub.

 

The GM rotor that normally is used in this application is 12.8" and 1.28" thick.  1/3 of the thickness is mostly void space (no weight) as it is the vent area.  Guys cut them in half at the vents, then turn the (previously vent are) face smooth.  We dug up some rotors for a limo that are about .790" thick and 12.8" diameter, waiting for them to arrive to be weighed.  I have my doubts that they're any lighter, as most of what has happened is the vent area is smaller, and they have a thicker hat to incorporate a parking brake drum.  The K20 rotors most guys use are a front rotor, and they actually windowed the hat for whatever reason (airflow probably), so between that and the wider vent I doubt it weighs more.

 

The small Isuzu rotor is only 10.3" diameter, or something like that, IIRC.  Super small friction area, as the hat is the same size or larger than the comparable solid rotors.  It actually would probably be a good choice if a guy was running 6 lug hubs.

 

In short I doubt there is anything that exists that's really worth the hassle.  The conclusion I am at right now is to not worry about it.  I'm waiting for other ideas on hubs that don't cost a fortune, we're going to try weighing some and see what we can come up with.

 

 

Vented aftermarket.

[Joop]

What we use on many formula offroad rigs is just regular vented front disk from whatever make and model your axles are, machined down into one layer solid disks. Typicaly with volvo 850 rear calipers or any other dual side piston, non sliding caliper. Do this on all four corners and it give plenty stopping power for a few dollars for most offroad/4x4 scenarios. Much cheaper than the typical wilwood alternative. Calipers and pads are in stock at any parts store and disks just doesnt breake that often, you could probably run them untill you retire and still have miles left.