Brake disc question

UKTJ

UKTJ

TJ Addict
Joined
Dec 30, 2020
Messages
1,232
Location
Hampshire, UK
My question is, what size is the whole in a brake disc for a 1/2" wheel stud.

The reason for the question is I am swapping a high pinion Dana 30 into my TJ and at the same time doing a faitly common modification in the UK by using Grand Cherokee (WJ) knuckles, whih allows use of the larger WJ brake discs. To do this I need WJ discs redrilled to 5x4.5" pcd. I have found a company that can supply the discs redrilled, but they are now coming back asking what size the wholes need to be. I did ask them to simply drill the same size wholes that are in their TJ discs, but I guess they are looking to ensure that if it is wrong it is my fault not theirs, so they still wanted a size from me. I have told them the studs are 1/2" and asked them to drill the whole size they would normally use for a 1/2" stud, but I'm worried they will drill a 1/2" whole and that this could cause fitting issues.

Thanks in advance for any help.
 
UKTJ said:
My question is, what size is the whole in a brake disc for a 1/2" wheel stud.

The reason for the question is I am swapping a high pinion Dana 30 into my TJ and at the same time doing a faitly common modification in the UK by using Grand Cherokee (WJ) knuckles, whih allows use of the larger WJ brake discs. To do this I need WJ discs redrilled to 5x4.5" pcd. I have found a company that can supply the discs redrilled, but they are now coming back asking what size the wholes need to be. I did ask them to simply drill the same size wholes that are in their TJ discs, but I guess they are looking to ensure that if it is wrong it is my fault not theirs, so they still wanted a size from me. I have told them the studs are 1/2" and asked them to drill the whole size they would normally use for a 1/2" stud, but I'm worried they will drill a 1/2" whole and that this could cause fitting issues.

Thanks in advance for any help.
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I've done this route on my WJ conversion but check with @mrblaine. I believe you are better off with Ford SportTrac rotors. I can't remember the year. @mrblaine would know all about it. I believe he was the original master mind on that conversion.
 
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Andy-WhiteTJ said:
I've done this route on my WJ conversion but check with @mrblaine. I believe you are better off with Ford SportTrac rotors. I can't remember the year. @mrblaine would know all about it. I believe he was the original master mind on that conversion.
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Thanks for that, but I don't think the SporTrac was ever sold in the UK, so discs may be hard to come by.
 
Andy-WhiteTJ said:
I believe he was the original master mind on that conversion.
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As a point of clarification, I was not. Burnsville Offroad was written up in a magazine as having done it. They were the first I saw doing it. I was not at all enthralled with their methodology which just used a spacer behind the unit bearing which moved the registration of the unit bearing out into the spacer and completely missed the hole in the knuckle. I never did and never will think that is a good idea. Over the years I saw lots of different ways to do it, I was not a fan of most and especially any that modified the knuckles. That makes a quick repair very difficult. Also not a fan of welding on the 1/4" spacer that JKS et al do. Welding bows it and sucks the outer edge down. Plus that is the wrong offset if you don't want to machine down the bolt bosses for the caliper saddles.
 
Interesting. I do remember Burnsville Offroad having some web pages about it but that was a long time ago. I just remember people doing it from the time I joined the old Jeeps Unlimited forums. LOL. Your name kept coming up back then as the all knowing WJ conversion guy.
 
Andy-WhiteTJ said:
Interesting. I do remember Burnsville Offroad having some web pages about it but that was a long time ago. I just remember people doing it from the time I joined the old Jeeps Unlimited forums. LOL. Your name kept coming up back then as the all knowing WJ conversion guy.
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I did a ton of them.
 
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