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View Full Version : f-body to a-body brakes?


360Swinger
11-20-2003, 04:42 AM
i have a 72 swinger with drums all the way around, and i want at least ft. disc for now. a friend used to drag a f-body volare and got tired of it and is now parting it out, he told me he is only looking to get 500 for the chassis. for 500 the brakes alone are worth it as junkyard parts are sparce are incomplete, and new kits run along the lines of 1,300. so my question is will they fit?

delshin
11-20-2003, 06:17 AM
The F-Body (Volare) is a 76 - 80 vintage? These cars came with isolators on the K member, which required that the steering knuckle be taller. Check the distance between the ball joint knuckles. If it is taller you will get binding in the ball joints for your application.
But if you can find some A-Body disc brake steering knuckles, upper A -arms (bigger ball joints upper) and lower ball joint (bigger) you still can use the rest of his stuff (calipers, rotors, master cyl , proportioning valve). Not too sure if you can use his A-arms.
Good luck
del

dave571
11-20-2003, 03:06 PM
delshin is right

Spindles won't work. I had a customer try, to find that they would bolt in, but left the car with the wheels cambered out(at the top) a very visable amount.

340duster1
11-20-2003, 03:40 PM
The spindle won't work (as others have already said). They are one inch taller between the ball joints. The only things that are useful are the rotors, calipers and caliper brackets. Easier way is to find a 73-76 disc brake a-body. This is a good link for what you need:

http://www.moparaction.com/Tech/archive/disc-main.html

360Swinger
11-21-2003, 02:02 PM
great information, thank you for the replies. so i might as well look for another a-body with the ft. disc or buy the bolt on kits.

340duster1
11-21-2003, 02:06 PM
I would go the used route as the bolt on kits are $$$$

dartswinger74
11-21-2003, 09:47 PM
Not to be disagreeable but after being told by everyone they wouldnt work I swapped the f body spindles with my original a body disc spindles just to see for myself.

The result you ask.
After realigning no noticeable difference.

Check out this link
http://www.bigblockdart.com/spindles/spindles.htm

dave571
11-21-2003, 11:57 PM
I'm glad it worked out for you dartswinger74.

The guy who put them on his challenger(after I told him not to) and had to do it all over, is probably glad for you too.

I have heard of it working for some people, so we can hope.

I suppose if we're hoping it will work, we should also hope that that the change in Ball joint angle, doesn't cause the upper joint to fail. This has been known to happen as well.(results in complete loss of steering control)

I guess I'm thinking it makes more sense to do it with the parts that are right for the job. Not the ones that we know are visably wrong.

Not to disagree:argue:

dartswinger74
11-22-2003, 12:06 AM
Suit your self dave.
Ill keep using the wrong parts as they are about third of the price and readily available. If you think the spindles are a big no no I wont even post about the upper control arms Im working on.
:D :D

ehostler
11-22-2003, 12:36 AM
What??? F-body spindles are a third of the price of A-body spindles???

I think that I paid about $150 for my complete setup, on ebay. I got a functioning power booster, master cylinder, proportionary valve, spindles, turned rotors with new bearings, and new pads for that price. These all came off of a '73 Dart.

Are you really saying that you can get all of that for only $50 from an F-body???

340duster1
11-22-2003, 12:45 AM
The F-body spindles will cause exceessive camber gain. What this means is if you take a fast corner with significant body roll the top of the tire will move in and cause you to ride on the inside edge of the tire. As well the balljoint will bind at full travel. So I guess you can use them if you want, but I wouldn't go there.

dartswinger74
11-22-2003, 12:46 AM
A body stuff is rare here in the rust belt.I got my last 2 m body cars for free ed . 318 904 cars. 1 wrecked 1 rusted up. I stumble across them(f bodies as well ) every now and then for 100 bucks or less around here. Lots of parts will work on a bodies or other stuff. Im putting the 85 318 from one of them in an 89 dakota right now.
So you see how this can be much more economical.

River
11-22-2003, 10:46 AM
360Swinger, If you'd like to see the F-body parts installed on a set of frame rails, I'm 40min north of you. I'll put one on a set of A-body or B/E rails, whichever you'd like to see. We can go over the points in question, I'll show you computer data of all the angles and even do a rough alignment so you can see how much adjustment there is with this setup. You can decide if you want to use them or not. It's pointless to post any of it here I see, and I'd enjoy a visitor for a few hours.
Excessive camber gain LOL ...Don't forget to grease your muffler bearing at least once a week or it too will fail :crazy:

dave571
11-22-2003, 11:29 AM
Well, I guess because I didn't take pictures of the wheels being cambered too far, and the adjusters maxed, trying to correct the problem, while it was on my Hunter wheel alignment rack, I'm full of BS??

I guess I just thought it was common sence to use the parts that are proven to fit and are the same size as the ones that came out. I didn't think I'd need photo evidence, or a computer model to show the silliness of such a thing. You don't need to drive 40min to see the 1" difference in height.

But yes, it's pointless to post some things here, in neverland...where every 318 can pull a 12 second 1/4 mile, all a 340 needs is a cam and headers to make 500hp. and a no start situation can be blamed on not dialing in a cam shaft on installation.

360Swinger
11-22-2003, 03:04 PM
i appreciate the offer River, but it makes sense to use whats designed for the car. so i just have to do some shopping around and find some proper parts. ebay may be a good solution, i will be sure to check it out.

dwc43
11-22-2003, 04:54 PM
We have race and built race cars for years and the F body spindles will only fit F,M, and J cars only. IF installed on other cars tehy over angle the ball joints and put the upper A arm out of it's designed geometry range. There's not enough caster or camber adjustment in an A body to correct this and even if it was the A arm would still be out of the correct range and teh ball joint would still be over angled. They just want fit period.

360 swinger if you like we have a rear disc brake kit run you around 450 plus shipping. Has rotors, pads, hoses, mounts and everything you need to install it. If you had the disc brake nuckles I could set you up with a front disc kit for around 600 with everything you need all new and not used. e mail me if your interested. ******************** :D

dartswinger74
11-22-2003, 06:10 PM
Sorry to keep argueing with you guys but can someone please explain this over angling of the ball joints. Because with my suspension at each end of its travel The ball joints arent angled nearly as far as they can be.

Also if this is so wrong what about the spindle extensions used by gm guys for handling?

Dave I dont know anything about e bodies but all the a body cars i have owned need some sort of modification to get the alignment angles I desired.I am sure you are aware this is actually quite common with a bodies, hence the popularity of the offset control arm bushings.

Was the car you are talking about close to the end of its adjustment range before the spindle change?

dwc43
11-22-2003, 06:17 PM
Even with offset adjusters to gain more front end alignment the F body spindle will not work. It is too tall. The ball joints have a certain amouont of angle they can set at while at rest. When the suspenion travels up and down it will angle the joint to a point that is close to the max angle it can take. If it over angles it will bend, brake, or pop the ball out of the joint housing. With the taller F body spindles they are overangled from the beginning and at full travel they will bind, hit ,bend or break take your pick. They will not fit period so dont try this. Plus it throws off teh A arm geometry, ackerman and induces bump steer as well. All of these things will create a dangerous driving car that cant possible be aligned to spec and most importantly can get you killed if it breaks a joint or does not handle in a turn correctly. :D

dartswinger74
11-22-2003, 06:32 PM
thanks for the clarification on that. I guess I just wont tell my car it is a deathtrap.:D :D :D

River
11-22-2003, 08:43 PM
Perhaps I see the problem with our disagreement.
If the F spindle was 1" taller, I could see where it would cause the problems you've mentioned.
Just for some baseline info, the 73-up A & E disk spindles are the same. Also the 73-up B,F,J,M and R bodies all have the same disk spindle, which is the one we all call the F, or FMJ spindle.
However, the FJM spindle is only 3/8" taller than the A/E disk spindle. Actually it's a hair over 1/4" taller.

http://www.bigblockdart.com/oddstuff/ABspindles.jpg

I've tried disk spindles from a '74 disk brake Challenger, a '77 Cordoba, a 78 Aspen, an '85 5th Ave, and an '81 New Yorker. All of them matched up to the A/E disk spindle like the ones in this picture - just a hair taller. These are the spindles I based all my research on, both on the suspension jigs and with software, and came up with a difference so small it was barely worth talking about, although on paper, the difference was for the better on an A-body. During these tests, I removed the rubber bumpstops and the lower arm hit the frame rail before the balljoint stopped the travel - and going down, the upper arm rested on the metal bracket before the balljoint stopped it. After all this, a friend of mine used the above Cordoba spindles on his Duster with no trouble, and another friend used the 5th Ave spindles on his 65 Belv. with no trouble. Also, I know at least one of the companies offering the previously mentioned $1300 conversion kits is using - you guessed it, the F spindle - even in the A and E body kits.
Based on all this, you can well imagine why I fiercely hold my position on the subject.

So, I fully believe that your statements are truthful, given you had a spindle that was an inch taller. What I would question is where did a Mopar spindle that tall come from? If the Volare spindle is different than the Aspen one, I'll be the first one to apologize for any criticism. I'd also change my tech page immediately, as I don't much care for giving out wrong information - wrong info is worse than none at all.

dwc43
11-22-2003, 08:53 PM
Take a good look at that pic you posted. See the difference in angles where the upper ball joint mounts. This is another reason why you cant use this spindle. It throws the steering geometry off since all of the other parts you will be using was made for a different spindle. Ackerman, bumpsteer, caster, camber, and toe during cornering will all be different fron the designed original pieces. :D

dave571
11-22-2003, 09:17 PM
In all fairness to the debate, I don't actually know what the spindles came off of, as I didn't pull them, or install them.(I only saw the after effects, and tried to correct)

The Customer had indicated it was an F body. In hein sight, that guy wasn't super intutitive(if you know what I mean) So who knows what they came off of.

That's a good point to bring up. I don't want to spread false info either, and I can't say for sure, since I didn't do it. I took the guy at his word, and the results seemed consistant with what I expected to see, in such a situation.

I'm not saying they weren't F body spindles either, I'm saying I can't be 100%


All I know is the difference was no good.

I am familiar with the a body, not having enough camber, problem. I've owned a couple like that, and had to compromise the alignment on a few as well.

We can only go with what we've seen.

River
11-22-2003, 09:39 PM
Yes, the difference does cause changes. The FJM spindle has an SAI angle of 8 degrees, and the A/E spindle has an SAI of 7.5 degrees. By itself, the greater SAI will increase stability and the self-centering effect. It does produce other changes in geometry, which can be seen in these text files ... I don't know how to put a table in a post...

73-up A Body Spindle Dive Test (http://www.bigblockdart.com/oddstuff/aspindledive.txt)
73-up A Body Spindle Steer Test (http://www.bigblockdart.com/oddstuff/aspindlesteer.txt)
73-up BFJMR Body Spindle Dive Test (http://www.bigblockdart.com/oddstuff/bspindledive.txt)
73-up BFJMR Body Spindle Steer Test (http://www.bigblockdart.com/oddstuff/bspindlesteer.txt)

Both tests were done using the same car and suspension, and I only changed the spindles and re-aligned it, hoping to get a true difference of just the spindles.

Ride height of both systems, which is "0" in the tables, is exactly 1" lower than the center of the available travel. It was tough to decide what "ride height" should be, so I just found the center of travel and lowered it an inch.
I'll also note that I had no trouble aligning the test A-body(69 Dart), or my friends' 2 cars, but as these cars have trouble as it is, maybe some cars do have trouble hitting zero camber.

Oh...you'll notice bumpsteer is worse in one direction using either spindle. If you adjust the tie rod ends as mentioned in the Mopar Chassis Manual, you can even out the bumpsteer, and when you do this, the FJM spindle ends up to be less either way than the A/E spindle. The bumpsteer isn't bad with either spindle though and for an average street machine, adjusting it would be getting a little picky. Well, actually you adjust the steering box and idler arm, not the tie rod ends.

dartswinger74
11-22-2003, 11:56 PM
Before I forget I thought I'd throw out a just a little F.Y.I on the lack of adjustment on these cars with the f spindles.
I still maneaged to dial in - .5 camber and + 5.0 caster. The identical settings I had before I swapped spindles without eccentric upper control arm bushings. These are far from factory specs but it is also the best htis thing has evre handled.

Thanks for the info bill.