1980 F-body disc brakes on a 1970 B-body. What swaps over?

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!

https://www.allpar.com/history/mopar/brakes/disc-main.html

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 If they felt it was apples/apples or at least of marginal difference they would have superseded to the taller spindle across the A/B/E platform.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.

http://www.bigblockdart.com/techpages/spindles.shtml

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.

http://www.doctordiff.com/front-disc-brake-kit-for-11.75-on-disc-knuckles.html

The car has 10" manual drums now.

A pal is selling a rusty 1980 F-body, but the brakes still work, so......

That is why I am asking.

I have already agreed to buy it, but the final price is flexible depending on what all I can use.

And you keep saying they're readily available...maybe in your neighborhood, not mine.

you can use the spindles, just do the research so you get the right calipers and hoses (or just order them from doctor diff).
if your car has a factory sway bar then you want to mount the calipers to the rear, no sway bar or aftermarket, then you can front mount the calipers (swapping the spindles on each side) and the brake hose routing will be cleaner...

if the calipers on the donor car are good, you can just use all that stuff and mount the calipers on the rear like factory.
i would buy some firm feel upper control arms though so you can run more modern alignment specs since we aren't all driving on bias ply tires anymore like the cars were originally spec'd for...

Go with the FMJ stuff, it will work fine.

I've done a bunch of cars with both A and FMJ stuff, none drove as through they were going to toss you off the road from bump steer.

One had about 50K miles on an FMJ swap when I sold it.

The scare mongers still exist from the article written in the 90's where IIRC, the author has said he'd never heard of a ball joint failure directly related to the additional spindle height. A friend ran the numbers and the additional angle at ball joint was 1.5* at both ends IIRC, 3* total through the swing. I'm pretty sure the ball joint tolerances were not built where an additional 1.5* was going to jam a stud to housing. This garbage is like a scary movie that isn't so scary...

Barry
take the spindles and caliper adapters from the F body and lovingly install them on the B Body. Buy new rotors, calipers, bearings and seals from rock auto, get some carbon metallic brake pads from firm feel and never worry about stopping. Dr Diff for brake lines. The naysayers are misspoken about the geometry as the evil spindles actually improve the roll center of the vehicle. I did not invent this reality but this is from very smart people who have analyzed the geometry of the spindles and my practical experience of using the evil spindles to run many laps at warp speed at my favorite road course. Otay?

Got it.

Thanks again all.

I have an appointment to see the brakes in person in the morning.

I've done this swap many times. Yes the spindle is taller. But what does this impact? If you study front suspension geometry you can see. It raises the the upper ball joint. Actual measurement is close to 3/8". As the upper control arm is normally angled downward this raises it causing the top of the tire to tilt outward. Is this a bad thing? Not really. Now the rear cam can be moved inward adding positive caster without creating excessive negative camber. This similar to adding offset upper bushings to add positive caster. It gives more range of adjustment. My background? ASE Master tech, my specialty? Front suspension and body shop wrecks for over 30 years. Yes I've aligned plenty of them myself. I can tell you it works because I've tested it, not just theory. Dizusters 140 mph turbo 62 Savoy runs FMJ with no issue, I've made passes in it. No difference between it and my 150 mph 64 Belvedere that has the toe pattern optimized to .10 degree though out total travel.
Doug

Thanks for the votes of confidence from everyone . . . I know from my experience, that this is a no brainer swap !! As mentioned, 10k miles of real world driving . . . go for it

F body knuckles on this car. It went 150+ mph at Portland International on the front straight and corners as well as the Vipers and Vettes.

I've had spindles from a '77 Volare on my '71 Charger for over 20 years. In that time, I've run them with stock control arms, CAP (now QA1) control arms, and, currently, CAP lower and Hotchkis upper control arms. I just used '73 Charger brake hoses.

You need everything in between the ball joints.



True, but the 10.5 F body units are not too shabby for a cruiser.



Uhhh, how long have you been on moparts? This topic has been beat to death on here every few years since the mid 1990s from every angle possible. Significant research has been done into it and for all intent, it is a non-issue for all but a few small minority.

OK, I went to look at the doner car. The entire brake system is complete.
The metering block is all there & the brakes do work.

So, I feel that we have the front discs covered, so what about adding the power booster setup?

Car is a manual brake car right now, so what would be needed to swap in the power goodies?

Thanks again!

I swapped over the entire 1975 Dart booster, brackets, knuckles and everything to my 70 Charger in 2002. The Charger was a 4 wheel 10" drum car. I just attached the 75 Dart power brake pushrod from the Charger pedal to the booster. It all bolted in. Now, there were changes for the F body cars. The Dart had a standoff bracket that moved the booster away from the firewall. I'm not familiar with the F body booster mounting.

It will be at least two weeks before I can get the car here for a look at how the booster mounts, but here is a photo from the front.

My Sport Satellite was manual drum brake, and I left it "manual" when I went to disc brake . . . used the aluminum 2 bolt master cylinder with adapter. . . . no issue with brake pedal feeling "too" hard, works great without the power. . .

I want the power & a closer to stock appearance, just because.

(For my other 1970 B, I may have some cruise control questions for you in the future.)

no worries . . . ask away . . .

one thing you may run into using the F-body booster is, it might be too big in diameter causing interference with ????. you may also have to modify the firewall hole and the booster mounting holes. with that said, i used a diplomat booster when i switched over to discs on my 64 belvedere. i believe it is real close to the diameter of the F-body. i had to enlarge the rod through hole, and drill two extra holes in the firewall to mount the booster. there wasn't anything in the way to cause interference, as this was a low option car. just some things to consider. and yes, i used the taller spindles with no issues what so ever. if anyone would read up on roll couple and handling issues, the taller spindles would be the ones they would only consider. remember, ALL factory suspension systems [with only a few exceptions such as sporty, handling types] are a COMPROMISE so the masses can "drive" the car without getting into trouble. the factory engineers spend big bucks on design as has been stated, but for "joe average" ONLY, not for hot rod or sports car guys like us. this does not in any way reflect on the latest stuff out there today, only the stuff available "back in the day".

I did this swap about 15 years ago on a 67 Satellite. The only effect of the taller spindle is a little more camber gain as the suspension compresses.
The brake hose wants to be on the opposite side of the spindle so I fabbed up a bracket in the correct new location (such that the brake hose passes through the spindle pivot axis) and made a short section of hard line to connect from the new bracket to the old.
Worked great.