Questions on Liberty Rear disc on 8-3/4 per MoparAction Articles

[RhinoMan68]

Ok I realize I am being stupid here so please be patient. There are 2 MoparAction Articles outlining the very simple upgrade to 2007 and earlier Jeep Liberty discs. I was going down the road of doing the GM Rear calipers and yada..
yada not impressed so shifting gears to these.

Has anyone does this before? Question is basically the first article talks about having to machine down the caliper bracket, 2nd article doesn't mention it, so I missed something or I'm just being dumb....

 

[Kern Dog]

I have the Dr Diff 11.7" rear disc kit in my '70 Charger.
The car stops no better than it did with the 10" rear drums. To me, the discs look better but offer no benefits unless you are road racing the car.
If you're certain that you want to switch to discs, the reason that they mention machining down that mount is to maintain the same axle shaft depth into the 3rd member to keep the axle shaft end play within factory specs. If you have non adjustable axle bearings, you can skip the machine work and assemble it all as it is.

 

[NoCar340]

It's a single article printed across two issues. The machining was explained well in the first half, so he probably felt no need to repeat it in the second.

 

[72bluNblu]

The machining is required, the caliper brackets go from ~1/4" thick or so down to around .1" according to the article. That's more than can be adjusted out.

There's a thread on here by a couple members that did the Liberty conversion, it's a bit long and the relevant posts are mostly on the first and last page, the last page has some part numbers for a better brake cable solution than what was used in the article.
Liberty Rear Disk Brakes for A-Body

 

[KosmicKuda]

The machining is required, the caliper brackets go from ~1/4" thick or so down to around .1" according to the article. That's more than can be adjusted out.
Liberty Rear Disk Brakes for A-Body

I remember reading the articles when they were originally published in the magazine. One thing that jumped out to me was the machining required to bring the thickness down to 0.100. OK, not so bad if the bracket is steel but it is cast iron. A thin cast iron section is not a good thing when subjected to tensile loads. I remember thinking they are opening themselves up to liability issues.

I just re-read the part one article on the web-site and references to particular dimensions have been edited. For instance the .100 dimension now reads *****. Some other specifics have been changed too. Looks like Ehrenberg is trying to cover his butt.

I just obtained the factory brake assemblies to do this swap but I'm going to rethink. I can go to my son's shop on a weekend and do the machining for free. But like Kerndog said above, my 10X2-1/2 rear drums work fine.

The advantagees to me are they look better behind large open wheels and I'm always thinking about weight reduction and the Liberty discs ARE lighter.

 

[RhinoMan68]

I am having a hard time finding a machine shop willing/able to do it. Either they don't do automotive stuff anymore at all (liability reasons) or they don't feel comfortable having a way to secure the bracket while machining...

 

[72bluNblu]

I remember reading the articles when they were originally published in the magazine. One thing that jumped out to me was the machining required to bring the thickness down to 0.100. OK, not so bad if the bracket is steel but it is cast iron. A thin cast iron section is not a good thing when subjected to tensile loads. I remember thinking they are opening themselves up to liability issues.

I just re-read the part one article on the web-site and references to particular dimensions have been edited. For instance the .100 dimension now reads *****. Some other specifics have been changed too. Looks like Ehrenberg is trying to cover his butt.

I just obtained the factory brake assemblies to do this swap but I'm going to rethink. I can go to my son's shop on a weekend and do the machining for free. But like Kerndog said above, my 10X2-1/2 rear drums work fine.

The advantagees to me are they look better behind large open wheels and I'm always thinking about weight reduction and the Liberty discs ARE lighter.

Yeah I don’t see this as a great upgrade vs. the kits already available. I run DoctorDiff’s 11.7” rear disks on my Duster and they work great and can be used with the factory tapered bearings.

After you track down the parts, spend the time pulling them, and then the machining I don’t see it as a great savings compared to just buying one of the kits already out there. If you consider your time as free and have access to someone to do the machining cheap then maybe. Even then you still need to solve the cable issue.

For my time/money I’d rather go with DoctorDiff, they’re proven. Just my opinion of course.

 

[jos51700]

If I'm not mistaken, the 8 3/4 requires the machining, 8 1/4 does not. It's been awhile since I read it.

ANY machine shop should be able to do this