Min thickness of brake disks

[gorman]

On brake drums and disks there are always a min thickness or max diameter written on the disks/drums. Does anyone know how important these figures are and why they are listed on the disks/drums?

Reason for asking is that I bought some WJ brake parts to go with my knuckle swop. The calipers look fine (they are 2003+ Akebonos)and they sent me some nearly brand new brake pads as part of the deal. When I initially inspected the parts the condition of the disks looked nearly too good. On closer inspection I noticed some machining marks on the surface which led me to believe they were skimmed. So I took my vernier and yep, they were skimmed. Now the potential problem - on the disks it is stamped/cast that the min thickness is 24.5mm (1"). On measuring it with my vernier the one measured exactly 24.5mm while the other one came in at just below that on 24mm. I did a search on Google and it seemed that some other aftermarket disks which lists the same min thickness have OE thicknesses of 26mm. Is this min thickness the minimum safe distance the calipers can handle when the pads wear out or is it to prevent them from warping - will I be okay in using them as they are?

For what it's worth, I have a brand new pair of XJ slotted disks that were going to go on before I decided to do the knuckle swop - I measured those and they were about 24mm.

 

[cal]

That thickness is the minimum for not breaking, overextending calipers, warping, etc.

If you are within 1mm of it and they are already machined, run them. Just count on not machining them again - the next time around pickup some new ones.

 

[gorman]

Thanks, that give me some peace of mind.

 

[yossarian19]

Gorman -
I'm working on my grad school application for Stellenbosch. Where are you in ZA? How easy is it to find XJ parts? I'm not sure if I want to bring my jeep with me if / when I go... Might do better to find something with a 4 cyl diesel and great fuel economy... Hell, a Bantam or a Taz might work...

 

[gorman]

Yossarian, I'm in Cape Town. Stellenbosch is a stone throw away from me (about 40km). Have you been in South Africa before?

XJ parts are readily available, but it also depends on what you're after. Any replacement part is no problem, but when you start doing some mods, etc. parts are a bit harder to find as there aren't many XJ's in junkyards. Also, wrt suspension mods - there's a couple of places that import suspension kits from the US, but other than that the main brands of suspension upgrades are OME and Ironman. I've never heard the US guys mention Ironman so I'm not sure if it is available there, but it is a very nice lift - similar in components to OME (i.e. coils, leafs and shocks - no control arms, trackbars, etc.) but it lifts a little higher than OME - I'd say at least 3".

 

[yossarian19]

I spent ten weeks in the Western Cape, centered in belltown (spelling?) and then took a one-week road trip to Windhoek through the hills, back south on the coast.
Changed my life. Want to go back soon but airfare ain't cheap.
I'll get a hold of you by PM next week, I'm about to head into the woods with work and wont be available.