FMJ caliper interchange questions

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Mopar92

Mopar92

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I was at the auto parts store today. Got into a conversation about A body’s. The guy tells me that FMJ spindles fit. Which I know. I’m at the crossroads of calipers now. Sadly these aren’t $12 like they used to be. Anyway, I don’t have cores so I’m paying the full boat retail sadly. Anyway here are my questions.
1- can the spindle be used on either side ? Does it matter?
2- what caliper do I want so I can run in the rear for ARB clearance up front ?
He said Vans of some years fit that spindle. I was unaware of that and am not sure about it. Thanks guys.
 
The spindles can be used on either side. It does matter because it changes the caliper location, front or rear, depending on which side the spindles are mounted.

As for the calipers, this is what Cass (DoctorDiff), says on the matter...
DoctorDiff said:
You must mount the calipers toward the rear if you are working on an A-body with a '72 and older sway bar.

'80 and newer F-body calipers and '69 Camaro front disc hoses work nicely when mounted toward the rear.

'79 and older F-body calipers and '73-'76 A-body front disc hoses work nicley when mounted toward the front.
Click to expand...

As far as the van calipers, I would say no. They usually shared parts with trucks or C-bodies, and those don't interchange with A/B/E/F/M/J bodies.
 
Yeah I called BS on the van thing as well, though I didn’t look at one. Cass quoted “72 and earlier”. So does the 73-76 sway bar cars need to mount to the rear?
 
Mopar92 said:
Yeah I called BS on the van thing as well, though I didn’t look at one. Cass quoted “72 and earlier”. So does the 73-76 sway bar cars need to mount to the rear?
Click to expand...

73-76 cars with a sway bar can have the calipers mounted to the front or the rear, although to the front is easier for brake line routing and that's how Cass sets up his 73-76 kit...

10.95" Front Disc Brake Kit (Stage 1)
 
20170704_220712.jpg

Here you go. Calipers in the rear sway bar in front. And yes! 1969 Camaro brake hoses.
 
My '73 Dart has stock disc spindles, late B-body brackets, '73 C-body calipers and '73 11.75" rotors.
 
My '72 uses '74-'76 Dart calipers AND hoses, AND swaybar, and they install as easy and same place as stock.....Jesus, Dr. Diff loves to over-complicate his stuff.
 
jos51700 said:
My '72 uses '74-'76 Dart calipers AND hoses, AND swaybar, and they install as easy and same place as stock.....Jesus, Dr. Diff loves to over-complicate his stuff.
Click to expand...
His brake selection is pretty big. He’s a nice and knowledgeable guy though. He’s helped a lot of people on the forums etc.
 
jos51700 said:
My '72 uses '74-'76 Dart calipers AND hoses, AND swaybar, and they install as easy and same place as stock.....Jesus, Dr. Diff loves to over-complicate his stuff.
Click to expand...

He’s set up to do conversions. He offers several options depending on how your car is set up. That’s not overly complicated, it’s good business. And how complicated is it to click a box on a web page? Sheesh.

And you use a ‘74 sway bar with a ‘72 K frame? Or are you not telling us everything? Because you have to switch the location of the calipers if you use 73-76 brakes with a 67-72 K and sway bar (unless you shorten the end links, which is another option).Which requires longer hoses. Which is why there’s more than one option.
 
Last edited:
Mopar92 said:
73 up K with ARB. 73 up FMJ setup. Thanks
Click to expand...

That's easy. You can use all 73-76 A-body parts.

Although the later FMJ calipers that Cass recommends will have a larger caliper bore than the 73-76 A-body calipers. So using the later calipers will increase the braking power in the front.
 
72bluNblu said:
He’s set up to do conversions. He offers several options depending on how your car is set up. That’s not overly complicated, it’s good business. And how complicated is it to click a box on a web page? Sheesh.

And you use a ‘74 sway bar with a ‘72 K frame? Or are you not telling us everything? Because you have to switch the location of the calipers if you use 73-76 brakes with a 67-72 K and sway bar (unless you shorten the end links, which is another option).Which requires longer hoses. Which is why there’s more than one option.
Click to expand...

I just rob all the crap from the same donor car and ZERO headaches. THAT is even easier than clicking a box on a web page. As a matter of fact, I did mine before there were web pages.....

Chrysler paid the engineers to get it right so I don't have to.
 
jos51700 said:
I just rob all the crap from the same donor car and ZERO headaches. THAT is even easier than clicking a box on a web page. As a matter of fact, I did mine before there were web pages.....

Chrysler paid the engineers to get it right so I don't have to.
Click to expand...

Right, you just did a full 73+ swap with all stock parts, so it's easy. Not everyone does that, and you don't need to either. You can leave the K, sway bar, and steering completely alone. But when you start mixing and matching the 67-72 parts with the 73+ brakes there are a couple little things that you need to do to make it work. It works just as well, you just need a couple of different parts.

And, if you buy it all from DoctorDiff, or even just look up the part numbers for the parts he lists (since they're all factory parts), there are zero headaches. Because he's already figured out which calipers and hoses give you the best hose routing when you move the calipers to the rear to clear the 67-72 sway bar.

I don't see what's hard about this. You can make your car perform a heck of a lot better than the Chrysler engineers did if you make educated improvements to your car, but that does involve making some decisions.
 
72bluNblu said:
Right, you just did a full 73+ swap with all stock parts, so it's easy. Not everyone does that, and you don't need to either. You can leave the K, sway bar, and steering completely alone. But when you start mixing and matching the 67-72 parts with the 73+ brakes there are a couple little things that you need to do to make it work. It works just as well, you just need a couple of different parts.

And, if you buy it all from DoctorDiff, or even just look up the part numbers for the parts he lists (since they're all factory parts), there are zero headaches. Because he's already figured out which calipers and hoses give you the best hose routing when you move the calipers to the rear to clear the 67-72 sway bar.

I don't see what's hard about this. You can make your car perform a heck of a lot better than the Chrysler engineers did if you make educated improvements to your car, but that does involve making some decisions.
Click to expand...

So what's the big advantage of mixing and matching parts over a full swap, other than if you have limited parts availability?
 
jos51700 said:
So what's the big advantage of mixing and matching parts over a full swap, other than if you have limited parts availability?
Click to expand...

Not having to find and pay for a 73+ K, LCA’s and sway bar? Or having to remove your original stuff and swap it out?

67Dart273 said:
I think you pretty much nailed it, LOL
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Exactly.

Even here in California the 73+ A bodies in regular wrecking yards have pretty much completely dried up. If you pull spindles and brakes off an FMJ car you don’t get a K member or control arms so you end up keeping your early sway bar. And that means calipers to the rear. But even the FMJ cars don’t hit the yards very often anymore. On top of that, the calipers usually cost as much or more at the yard than what you get for a core charge on new calipers, so, why mess with nasty wrecking yard calipers at all?

Plus it’s just more work to swap everything. Yeah, the spool mount K’s have better engine mounts, but that’s a lot of work for no real significant gain. The sway bar is the better improvement, the ‘73+ style improves clearance by running through the K, and you can run wider tires without interference. But for a lot of folks there’s no real reason to swap that stuff.

I just don’t see what the beef is. Cass went through the trouble to figure out which calipers and hoses fit each configuration best, and somehow that’s a problem?
 
72bluNblu said:
Not having to find and pay for a 73+ K, LCA’s and sway bar? Or having to remove your original stuff and swap it out?



Exactly.

Even here in California the 73+ A bodies in regular wrecking yards have pretty much completely dried up. If you pull spindles and brakes off an FMJ car you don’t get a K member or control arms so you end up keeping your early sway bar. And that means calipers to the rear. But even the FMJ cars don’t hit the yards very often anymore. On top of that, the calipers usually cost as much or more at the yard than what you get for a core charge on new calipers, so, why mess with nasty wrecking yard calipers at all?

Plus it’s just more work to swap everything. Yeah, the spool mount K’s have better engine mounts, but that’s a lot of work for no real significant gain. The sway bar is the better improvement, the ‘73+ style improves clearance by running through the K, and you can run wider tires without interference. But for a lot of folks there’s no real reason to swap that stuff.

I just don’t see what the beef is. Cass went through the trouble to figure out which calipers and hoses fit each configuration best, and somehow that’s a problem?
Click to expand...

And that’s exactly why I pieced this together. I’d have loved to have found a 73-76 donor.
 
Didn't realize parts cars of that era were so hard to find....
 
jos51700 said:
Didn't realize parts cars of that era were so hard to find....
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Availability has changed a lot in just the last few years. 5-6 year ago I would make 10-12 trips a year to the local pick and pulls (I have 4 within an hour of me) to pull parts from donor Mopars. A’s, C’s, and FMJ cars mostly, an occasional B/R body (76-79). I’ve pulled 8 3/4’s, several disk conversions, my whole fold down seat conversion for my Duster, even a whole ‘71 Dart front clip. But in the last 2-3 years I’ve probably only gone once or twice a year, and not for any A-bodies at all. It’s not totally impossible to find that stuff, but you can’t just head down to the yard whenever you want and find what you need.
 
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