1980 F-body power disc brakes on a 1970 manual drum B-body chassis. What swaps over & what if any additional parts would be needed to convert them?

15" wheel car.

Thanks!

Should basically bolt on. You'll probably need custom brake hoses.

Someone correct me if I'm wrong but I believe if you want to use 11.75 rotors you need B-body Cordoba caliper adapters too. These are available repopped from Dr Diff and others.

Kevin

The F-body spindles are not the correct height. They are taller and will skew the suspension geometry. You want 73-76 A-body or 73/74 E-body.

I will chime in, as I have done the F,M,J body disc swap on my 70 Sport Satellite . . . no issue with the taller (think it is like 1/8"??) spindle. My car has 10,000 miles on it since doing . . . couple things I ran into . . . needed to put a washer on the bottom original bolts (on the nut side), used rear mount calipers (think from 5th ave), so that bleeder screw was in upper position, and stainless steel brake lines from Dr. Diff . . . no issues at all !!! Think I used the larger rotors with the caliper adapter . . . no tire wear issues - the larger spindle issue is supposedly at FULL extension, where the upper ball joint "might" bind or hit ?? . . . I have never had issue (also used tubular upper control arms from Firm Feel) . . . all is talk until you do it in real world . . . just saying . . . Oh, and yes, have 15x7 road wheels (magnum 500's) . . .

Cheers

Mark

You have a lot of other variables going on there than just spindles. There is also the difference between what is passable and what is ideal. The right spindles are not that hard to find. Keep in mind that Chrysler produced BOTH types concurrently for several years. If they felt it was apples/apples or at least of marginal difference they would have superseded to the taller spindle across the A/B/E platform.

If you are going with tubular arms and other non-OE pieces then it probably doesn't matter. Those parts will most likely provide the adjustment necessary to get things back into spec, which you can more easily accomplish by simply using the right spindles to begin with.

From the spindles out swap over.

FMJ spindles work fine on the B's and have better geometry in some of the ranges than the stock stuff. Require no special adjustments.

The overangling and stressing ball joints claims is nonsense.

There is a good write up about the spindles at BB Dart.

It's a compromise. If you're fine with that, when the proper parts are readily available, then that's up to you. I have to think that the Chrysler engineer department had a slightly bigger budget than BigBlockDart.com. Their testing, BTW, is full of caveats - baseline settings different from factory specs, and comments like, "how often is your suspension fully extended on main street?," things that tell me we are getting a little off the beaten path. If you are the type who insists on aligning a car in your own garage, then I'd be less worried. Personally, I'd like to be able to go into most any shop from Anchorage to Albuquerque and not worry about having to give a dissertation on my custom needs. We all don't have race/rally cars.


There is a reason why car companies perform extensive testing, both in the lab and on the road, to find the bugs that one or two static tests will not show. And yet billion dollar, multi-national companies still find flaws once the product has been tested to a level they believe is beyond doubt and is out the door. Can you probably rack up tens of thousands of miles without worry? Maybe. But it's not like we are putting juice brakes on a model A - the proper OE parts ARE out there, and available. We aren't talking about a whole lot more effort to do it right.

The FMJ spindles are not an issue - they are a factory built part. They have been tested by Ma Mopar. The spindles are not going to disintegrate or come apart, and the issue on alignment - no issue. I took my car to the shop and did not mention a thing, they lined it up and it tracks perfect and is not wearing tires, steers and brakes like it should.

Why should it matter if "you align it yourself" in your garage, versus paying for a shop to do the same thing ???

Is that like saying that those that "restore a car themselves" are not as good as paying HUGE $$$$ to a shop to restore the car . . . I know some great mechanics that I would not say are "backyard", they could work in any shop they wanted.

If the after market builds parts, they are tested too - otherwise the lawyers will be on their heels quicker than you can say boo !

What you have to watch using the FMJ spindle, is using the correct caliper that has the bleeder screw at the top, and getting a correct brake line that can be routed correctly and not kink through out the movement. As mentioned, Dr. Diff has stainless steel line that works perfect.

The write up on BB Dart states everything perfectly . . . no issue to worry about . . . the spindles are factory, the alignment specs are factory, the brake calipers/rotors are factory. The hoses, well, they are after market which is actual UPGRADE from factory ! . . . actually, the spindles HELP with some of the alignment issues that happen to the cars over the years.

If you ONLY USE NOS/FACTORY parts for your car, because they are FACTORY and won't look at "aftermarket" parts, you sure have more $$$ to spend on your car than I do . . .

Yep, for a different platform.



Yep, and they are intentionally different for a reason because "Ma" knew they needed to be.



Yes, because the extremely limited static measurements from an alignment rack will guarantee your setup as fool proof, and are identical to the care and cubic dollars that were engineered in by Chrysler Co.



You are missing the point entirely. We have members who actually race their cars. These cars are well beyond factory tolerances, and come complete with custom parts set at custom specs. They will have caster/camber settings that a street car will not, but more importantly these people will know their vehicle a heck of a lot better than the average enthusiast who simply wants cheap disc brakes. Not everyone has the knowledge base, and those who do should not recommend changes that would ordinarily be part of a larger picture.




I have no issue with aftermarket parts. But then again that's not what we are talking about. What we ARE talking about is needlessly using an incorrect factory part.

Let's start over. Do you want to buy things like tubular upper arms to compensate for a taller spindle? Do you know what your custom alignment specs should be for the best result? Can you explain them to an alignment tech, and know what might result if he/she can't get the car into spec? Do you plan to race the car, or will it be mostly used on the street? Will anyone other than you drive the car (spouse, children, etc.), and are you comfortable with them having to operate a car with a custom suspension setup? Do you put websites like bigblockdart.com on par with Chrysler Engineering? Your answers will guide your decision.

I do not race my car, I drive it far distances for my own pleasure ! The tubular upper control arms correct the fact we don't get enough camber in our cars, especially over the years as things wear and "sag" . . . why did Moog bring out "correction bushings" ??? Exactly same thing !!!

The tubular upper control arms are NOT correcting a 3/8" taller spindle . . . and if you have an "old school" experienced mechanic, they can understand the car alignment issues better than "those racing their cars" . . .

I am putting my decision on parts usage on my "real world" experience and that of those whom I trust in the hobby . . .

With your thinking, then going to a 15" wheel/tire combo which may not have been stock on a car, is a no no . . .

What I am saying is that this is not an apples to apples swap - there are differences and members like Alaskan TA should be given all of the information so that they can make the choice that is right for them. What he intends to do with the car, who will drive it, and his level of understanding with regards to suspension geometry will dictate which path he takes.

I am saying it is REAL WORLD experience on MY END talking . . .

I got no dog is this fight, but could that statement be equated to the following?

"I never worn a seat belt for the last 20yrs and never got hurt, so not wearing your seat belt is competelty safe"?

Hey guys,
I appreciate all the helpful responses.

No need to argue though.

Car will not be raced, just street driven.

I am not a fan of tubular arms, I have seen more photos of those broken than factory arms, so we can leave custom parts out of the discussion as far as this car is concerned.

I also wear my seat belts.

Thanks!

if you don't want the tubular upper arms and all that, then just order the disc brake kit from dr diff. the one with the repro a-body spindles and bolt it all on...

my car had the FMJ spindles and some tubular upper arms i didn't want to risk, so i ordered some upper arms from firm feel, swapped the spindles side to side to put the calipers in the front and got some brake hoses from dr diff (though i could've used the factory 74-76 a body brake hoses and saved $30)

If you want the car to operate exactly the same but with unicast discs, then you need the 73-76 A-body or 73-74 E-body spindle, which is exactly the same height as what you have now.