Liberty Rear Disk Brakes for A-Body

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As for using Green Bearing, I would never touch them. I got less than 500 miles on the set I used on my car years ago. They simply cannot handle side loads and destroy themselves when used for cornering.

bullshit.. what did you do wrong when installing them? something was wrong somewhere..

hell the green bearing in jamies dart are the same ones i put in that rear in the mid to late 90's. tons or hard street and strip miles on them.. to only get 500 miles out of them there was a problem somewhere other then the bearings..
 
Why is it the “green bearings” get the blame for all kinds of stuff and yet the most “useable rear known to man, the ferd 9 inch” uses a green bearing style bearing and people love those rears?

Sorry, just have to ask.
 
That's why I went with the Cherokee set up you just had to enlarge the hole for the axel tube a bit with a die grinder, from there straight bolt up to mount it.
 
High res picture album of both articles.

 
This topic is getting beat to death. Bet we can get 87 more post to this. And still get nowhere.
 
Just waiting to find out if machining the mount down to .1 inch thickness will actually hold up.
 
Yikes. God tell me he won't drive his family in this cobbled up brake job.
 
Why is it the “green bearings” get the blame for all kinds of stuff and yet the most “useable rear known to man, the ferd 9 inch” uses a green bearing style bearing and people love those rears?

Sorry, just have to ask.

Because there really was a design problem with the “first generation” of the green bearings. And because guys like Ehrenberg STILL tell people they put their “lives in danger” running green bearings even though that’s been total BS since the redesigned bearings came out well over a decade ago.

The write up Cass did that I linked in post #16 explains that, which also explains how the bad rap was initially earned.

High res picture album of both articles.



Careful with the copyright laws posting that. It’s not like posting the old articles while the magazine was defunct.

Sadly I bought both magazines, what a rip off. Not at all impressed with that brake conversion, the amount of machining that has to be done seems like it would really weaken that mount. Now OE stuff usually has a pretty big safety factor built in, but I think going down to .1”, given what the factory put there, is probably pushing some luck. They don’t show the finished mount after it’s machined in much detail though, hard to tell.

And the cable mount/conversion they did is pretty amateur. I mean I’m sure it’ll work, but what they published looks like the shade tree shortcut version, not the version I’d expect to see published in a magazine. That’s one of those things I would have expected to see made custom for the article and then short cut by guys doing it themselves in their garage to save some time/money. Instead the magazine did the short cut and left folks that want a better thought out solution to find it for themselves. Kinda weak.

This topic is getting beat to death. Bet we can get 87 more post to this. And still get nowhere.

What we really need is a few more people to try it and post their findings. The article seems to gloss over some pretty important details of the installation.
 
I would use the factory flex hoses instead of flexing hard lines, swage old and new parking brake cables together which is easy, other than worried about thinning the mounting bracket basically a stock system. Am interested in doing this.
 
Amazing how people will risk their life and other innocent people to save $1
Hope your insurance is paid up.
 
If a proven brake system can be installed without sacrificing safety( once the thinner brackets are proven and factory cables and hoses are used) what is wrong with the system? And I saved a lot of money using the proven 73 up disc brakes on my 67. A lot of people have used these disc conversions without major issues.
 
73 & up brakes. Yes I agree. Shaving brackets down to 0.100 ? It's your family your putting at risk. The money you safe can go towards a upgrade on a casket.
 
73 & up brakes. Yes I agree. Shaving brackets down to 0.100 ? It's your family your putting at risk. The money you safe can go towards a upgrade on a casket.

I think you’re being a bit overly dramatic. The original backing plates for the OE drums on these cars are 11 gauge. That’s .1196” thick.

Now, they were designed to be that thickness, which is an important distinction because obviously the Liberty mounts were designed to be thicker for some reason. Although that reason may not just be strength, we don’t know. So that doesn’t necessarily mean machining them down to .1” makes the whole thing a death trap. The bracket mounts just like the original backing plates do.

I don’t like it either, but that’s just an opinion so far. I don’t think enough information, or pictures of the final machined brackets, have been posted yet to make a good determination on the viability of that modification. Certainly not on a long term basis. I’m no big fan of Ehrenburg, but I don’t imagine he’d hang his *** out quite that far. Because if it was truly that dangerous he could be liable for any accidents.

What is the brackets original thickness?

Based on the pictures in the article, the original bracket looks at least 3x as thick as that in the area where it’s being machined. But no measurements are given in the article, and there’s no clear picture showing the finished machinework on the bracket either, just what’s shown in picture #7 in the first part of the article. Which is a detail that should have really been included in the article, there’s still a lot of explaining you’d have to do to when you take those parts to your machinist. They didn’t paint a very clear picture of the modification. And it’s an important one!

Like I said, I’m not impressed so far. I’m not saying it won’t work, but I’m not at all sure it’s worth the effort compared to using the kits that are already out there and proven.
 
Regarding the liberty swap, I don't like machining the mount that thin but if it's forged it's probably ok. I realize it sees only torsional load, but that's still pretty thin. I have wide offset axles for bbp and fmj rear drums and wonder if I could go thicker on that flange.

The .100 thickness may be ok.
I'm actually more concerned about metal fatiguing by the addition of a machined pocket with the danger of introducing stress risers.
If I do this, I'm going to make sure to use a milling cutter with a radiused corner so there is a radius all the way around the bottom of the pocket.
It's one thing to use proven factory parts but when you start modifying them, all bets are off.
 
The .100 thickness may be ok.
I'm actually more concerned about metal fatiguing by the addition of a machined pocket with the danger of introducing stress risers.
If I do this, I'm going to make sure to use a milling cutter with a radiused corner so there is a radius all the way around the bottom of the pocket.
It's one thing to use proven factory parts but when you start modifying them, all bets are off.

I agree and thought the same thing. Having only seen the parts in photos and not first hand, it appears that the area in question is already milled on a factory forging, and it looks thin as delivered.

Has anyone figured out how much metal is really being removed?
 
The .100 thickness may be ok.
I'm actually more concerned about metal fatiguing by the addition of a machined pocket with the danger of introducing stress risers.
If I do this, I'm going to make sure to use a milling cutter with a radiused corner so there is a radius all the way around the bottom of the pocket.
It's one thing to use proven factory parts but when you start modifying them, all bets are off.

Totally agree.

The machining has to be done right for sure, if you have sharp edges on that pocket with that thickness of metal you're bound to get some cracks over time. The thickness of the bracket might be ok, but like you said, once you start modifying parts from the original design you're out on your own. Doesn't necessarily mean it won't work, but using proven parts doesn't guarantee success once you start cutting on them either.

I agree and thought the same thing. Having only seen the parts in photos and not first hand, it appears that the area in question is already milled on a factory forging, and it looks thin as delivered.

Has anyone figured out how much metal is really being removed?

Yeah it would have been really nice if they took better pictures of by far the most critical modification they made. Or described how much metal was removed.

It's almost like Ehrenberger wanted to show off more than he actually wants someone to use the article as instructions to modify their own car. Or maybe he left if vague so when someone loses their rear brakes and sues he can say they did it wrong?
 
One aspect of this swap that hasn't been directly addressed, which is especially significant in this forum, is that it won't work on A-Bodies with their original, stock 8.75" rears. The axles not only have the wrong bolt pattern and a smaller center register to fit the rotors, but due to the narrower brakes (1.75" vs. 2.5") the brake gap is much smaller. To get the caliper centered on the rotor, this would require machining away more of the bracket than actually exists.
A solution would be custom axles, which could restore the brake gap to the larger 2.525", and even an additional amount to make up for the material machined from the brackets. A neat solution, except for two things: 1) the cost for the project will more than double, which defeats the whole purpose of the low-buck nature of the swap, and 2) it would move the wheels somewhere around an inch out in the wheel well. Maybe that's not an issue for some, but it certainly will be for others. Of course the housing could be narrowed, and the use of custom axles, and unmachined brackets, but that's pretty severe mission creep and cost to go along with it. The OP, RLF Cuda, is already running the needed axles, so he's right where he needs to be with the swap. Although, if he really has 3", not 2.5" brakes, he might need to do some shimming, not machining of the brackets.
I'm still undecided if I'll do this or not. Maybe with re-splined C-Body axles...
 
One aspect of this swap that hasn't been directly addressed, which is especially significant in this forum, is that it won't work on A-Bodies with their original, stock 8.75" rears. The axles not only have the wrong bolt pattern and a smaller center register to fit the rotors, but due to the narrower brakes (1.75" vs. 2.5") the brake gap is much smaller. To get the caliper centered on the rotor, this would require machining away more of the bracket than actually exists.
A solution would be custom axles, which could restore the brake gap to the larger 2.525", and even an additional amount to make up for the material machined from the brackets. A neat solution, except for two things: 1) the cost for the project will more than double, which defeats the whole purpose of the low-buck nature of the swap, and 2) it would move the wheels somewhere around an inch out in the wheel well. Maybe that's not an issue for some, but it certainly will be for others. Of course the housing could be narrowed, and the use of custom axles, and unmachined brackets, but that's pretty severe mission creep and cost to go along with it. The OP, RLF Cuda, is already running the needed axles, so he's right where he needs to be with the swap. Although, if he really has 3", not 2.5" brakes, he might need to do some shimming, not machining of the brackets.
I'm still undecided if I'll do this or not. Maybe with re-splined C-Body axles...

There’s no axle difference between the 3” wide BBP rear drums and the 2.5” wide BBP rear drums. The difference is made up entirely in the offset of the backing plates, and since those aren’t used for this disk brake conversion there’s no difference in the procedure regardless of which BBP drums he has.

All stock spec BBP Mopar axles have the same axle flange stand off.

The only BBP axles out there that have a different axle flange offset are those stupid aftermarket Moser axles that have the 5x4.5” bolt pattern with a SBP axle flange stand off, so you have to keep the 10x1.75” drums and redrill them for 5x4.5”. Why anyone would do that is beyond me, but apparently they still make them.
 
One aspect of this swap that hasn't been directly addressed, which is especially significant in this forum, is that it won't work on A-Bodies with their original, stock 8.75" rears. The axles not only have the wrong bolt pattern and a smaller center register to fit the rotors, but due to the narrower brakes (1.75" vs. 2.5") the brake gap is much smaller. To get the caliper centered on the rotor, this would require machining away more of the bracket than actually exists.
A solution would be custom axles, which could restore the brake gap to the larger 2.525", and even an additional amount to make up for the material machined from the brackets. A neat solution, except for two things: 1) the cost for the project will more than double, which defeats the whole purpose of the low-buck nature of the swap, and 2) it would move the wheels somewhere around an inch out in the wheel well. Maybe that's not an issue for some, but it certainly will be for others. Of course the housing could be narrowed, and the use of custom axles, and unmachined brackets, but that's pretty severe mission creep and cost to go along with it. The OP, RLF Cuda, is already running the needed axles, so he's right where he needs to be with the swap. Although, if he really has 3", not 2.5" brakes, he might need to do some shimming, not machining of the brackets.
I'm still undecided if I'll do this or not. Maybe with re-splined C-Body axles...

Great point about the bolt pattern difference. I've had BBP axles in my car so long, I didn't think about it, but I did email Ehrenberg about the wider offset axle flange a week ago with no response. The guy is like 74, so....

There’s no axle difference between the 3” wide BBP rear drums and the 2.5” wide BBP rear drums. The difference is made up entirely in the offset of the backing plates, and since those aren’t used for this disk brake conversion there’s no difference in the procedure regardless of which BBP drums he has.

All stock spec BBP Mopar axles have the same axle flange stand off.

The only BBP axles out there that have a different axle flange offset are those stupid aftermarket Moser axles that have the 5x4.5” bolt pattern with a SBP axle flange stand off, so you have to keep the 10x1.75” drums and redrill them for 5x4.5”. Why anyone would do that is beyond me, but apparently they still make them.

Good point about the offset being built into the backing plate; also true.
 
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