Upper Control Arms in Disc Conversion

Hello all,

Getting ready to do the front brake conversion on my 74 Duster and might be really over thinking this hole thing. I got the 74 parts manual and was looking at it to help determine what parts I could get versus different level kits. From my understanding, 73+ all had the large upper ball joint in the control arm and one big thing a brake conversion talks about is changing the upper control arm because the 72- used small ball joints. Is the 73+ upper control arm the same on an A/E body? The 74 parts manual has me confused as it list several different parts numbers for upper control arms as follows: A-body with Drum Brakes (3722 460-1), Disc brakes (3402702-3) and E-body (1857 856-7). Is the A-Body control arms for Drum/Disc interchangeable, why would they have two different P/A's? Also, is the E-body control arm interchangeable with the A-body's? Any info would be great.

v/r
Ron

One thing i'll tell you is you can use the small ball joint spindle. Just have it machined to the larger size. IF you buy your upper A-arms from RMS he will machine and powdercoat your spindles. He didn't even charge me to do this.

I have to say with what these parts are going for now in the for sale section, PLUS shipping heavy *** parts PLUS clean up PLUs any additional parts you'll have to buy like pads, calpiers, fittings, lines etc. I think it makes the wilwood conversion look pretty damn appealing and you get a lot of benefits over the stock setup for going this route.

This beats the heck out of any of the after market prices!!

http://www.forabodiesonly.com/mopar/showthread.php?t=308429

treblig

Hello all, I had this posted in suspension and may be more app here.

Getting ready to do the front brake conversion on my 74 Duster and might be really over thinking this hole thing. I got the 74 parts manual and was looking at it to help determine what parts I could get versus different level kits. From my understanding, 73+ all had the large upper ball joint in the control arm and one big thing a brake conversion talks about is changing the upper control arm because the 72- used small ball joints. Is the 73+ upper control arm the same on an A/E body? The 74 parts manual has me confused as it list several different parts numbers for upper control arms as follows: A-body with Drum Brakes (3722 460-1), Disc brakes (3402702-3) and E-body (1857 856-7). Is the A-Body control arms for Drum/Disc interchangeable, why would they have two different P/N's? Also, is the E-body control arm interchangeable with the A-body's? Any info would be great. Also, looks like the spindles on 74 Disc A & E bodies were the same, is that accurate? I was contemplating getting a kit from the Ramman unless I can piece it together myself.

I appreciate any helpful input.

v/r
Ron

E bodies have a different A arm, I am going to use Ram Mans early A body kit, yours already has the large upper ball joint, let this thread ride today and see how many good tech will jump in and advise you, should be an easy install , so you have drums on your front ? Thats wired .

This beats the heck out of any of the after market prices!!

http://www.forabodiesonly.com/mopar/...d.php?t=308429


When I did the conversion on my '69 Barracuda I used 73-76 A body disc brake UCAs. As far as I know they are the only UCAs you can use. They have to be off a disc brake A body 73-76!! I also used 73 and up B body spindles because they are more abundant and fairy cheap. You also need 73 and up B body LBJ. If I remember correctly I also used 73/74 Charger rotors and calipers (pretty sure).

treblig

Treblig said:

This beats the heck out of any of the after market prices!!

http://www.forabodiesonly.com/mopar/...d.php?t=308429


When I did the conversion on my '69 Barracuda I used 73-76 A body disc brake UCAs. As far as I know they are the only UCAs you can use. They have to be off a disc brake A body 73-76!! I also used 73 and up B body spindles because they are more abundant and fairy cheap. You also need 73 and up B body LBJ. If I remember correctly I also used 73/74 Charger rotors and calipers (pretty sure).

treblig

Click to expand...

Thank you treblib :color: glad you jumped in and straightened us out on this :glasses7:
I did not know the drum spindles was different or that there was even drums in 1974 #-o

Treblig said:

This beats the heck out of any of the after market prices!!

http://www.forabodiesonly.com/mopar/...d.php?t=308429


When I did the conversion on my '69 Barracuda I used 73-76 A body disc brake UCAs. As far as I know they are the only UCAs you can use. They have to be off a disc brake A body 73-76!! I also used 73 and up B body spindles because they are more abundant and fairy cheap. You also need 73 and up B body LBJ. If I remember correctly I also used 73/74 Charger rotors and calipers (pretty sure).

treblig

Click to expand...

I guess what I'm digging for here is the difference between 73-76 a-body drum vs. disc UCA. Manual list two separate part #'s but they both utilize the larger upper ball joint, so are they interchangeable? Additionally, the 74 parts manual list the same Disc brake spindle for the a-body and the e-body. It is my understanding that the 63-4 b-body spindle is interchangeable with the 73-4 e-body, if so, wouldn't it be a bolt on for the 74 a-body?

I appreciate you posting the listing from the classifieds but I'm not really interested in using used parts for this specific task.

v/r
Ron

:burnout:

Thanx
I plan on doing the same thing.
I have all parts but UCA.
I'll probably get tubular UCAs

:burnout:

Duster_71 said:

I guess what I'm digging for here is the difference between 73-76 a-body drum vs. disc UCA. Manual list two separate part #'s but they both utilize the larger upper ball joint, so are they interchangeable? Additionally, the 74 parts manual list the same Disc brake spindle for the a-body and the e-body. It is my understanding that the 63-4 b-body spindle is interchangeable with the 73-4 e-body, if so, wouldn't it be a bolt on for the 74 a-body?

Click to expand...

Not a tech expert here by any means, but I thought the UCAs were the same, disc or drum. It's the spindle that's different between the two setups.

dozer556 said:

Not a tech expert here by any means, but I thought the UCAs were the same, disc or drum. It's the spindle that's different between the two setups.

Click to expand...

Dozer, If you read the links I posted earlier you'll find that there are two A body UCAs. One has a LBJ one has a SBJ. You can put disc brakes on a SBJ upper control arm but then you have to get other parts to get them to work. Plus the large ball joint UCAs give you larger brake rotor options anyway so it makes no sense to go with the SBJ UCAs..at least it didn't make sense to me. Either way I sold my SBJ UCAs in about 3 seconds here on FABO so it's worth it. You can also sell your whole drum front brake system when you're done getting some of your money back.

Treblig

Treblig said:

Dozer, If you read the links I posted earlier you'll find that there are two A body UCAs. One has a LBJ one has a SBJ. You can put disc brakes on a SBJ upper control arm but then you have to get other parts to get them to work. Plus the large ball joint UCAs give you larger brake rotor options anyway so it makes no sense to go with the SBJ UCAs..at least it didn't make sense to me. Either way I sold my SBJ UCAs in about 3 seconds here on FABO so it's worth it. You can also sell your whole drum front brake system when you're done getting some of your money back.

Treblig

Click to expand...

True, but UCAs between disc and drum setups are the same, if you're talking the same ball joint size, right?

In other words, UCAs with LBJs work on disc OR drum LBJ spindles. UCAs with SBJs work the same way, on disc or drum SBJ spindles.

Duster_71 was asking if the UCAs were the same between the disc and drum LBJ setup, even though they had different part #s. I believe they are the same, even though you stated in an earlier post that you used 73-76 A body disc brake UCAs on your swap.

Not trying to make anything more confusing, but I guess this all boils down to whether or not there are different LBJ UCAs for disc and drum systems. I know the disc and drum spindles are different but I believe the UCAs are the same.

*Edit* turns out I was wrong. Lol

Maybe it's the different bolt pattern between the drums and discs I was thinkin of?

dozer556 said:

True, but UCAs between disc and drum setups are the same, if you're talking the same ball joint size, right?

In other words, UCAs with LBJs work on disc OR drum LBJ spindles. UCAs with SBJs work the same way, on disc or drum SBJ spindles.

Duster_71 was asking if the UCAs were the same between the disc and drum LBJ setup, even though they had different part #s. I believe they are the same, even though you stated in an earlier post that you used 73-76 A body disc brake UCAs on your swap.

Not trying to make anything more confusing, but I guess this all boils down to whether or not there are different LBJ UCAs for disc and drum systems. I know the disc and drum spindles are different but I believe the UCAs are the same.

Click to expand...

According to the links I posted and what I have found there are two different upper control arms on A bodies. The disc brake upper control arms have a larger ball joint. The drum brake upper control arms have a smaller ball joint. This is probably because the disc brake can put a much higher load on the ball joint (better/faster braking). If you read all of the links I posted earlier you'll see which upper control arms have the large ball joint and which ones do not. You can't use the large disc brake rotors (like from a Charger) unless you convert to the large ball joint upper control arm and spindle because the disc brake B body spindle requires a larger ball joint in the upper control arm. You can rig it to work with a small ball joint but that would make no sense because of the higher loads. I know from the way my '69 Barracuda brakes....there is a world of difference in the stopping power now that I have switched to the big disc brake system.

The ball joints in disc brake and drum upper control arms are different!! When I ordered adjustable upper control arms for my Barracuda (after disc brake swap) there were different P/Ns for drum brake set-up versus disc brake set-up (different UBJs).

The lower ball joints are not an issue!!

Hope this helps.....

treblig

Boy oh boy, has there been a lot of misinformation being thrown out here in regards to upper control arms on the A body cars.
Now everyone listen up.
On the 73 -76 A body cars there is NO difference in UCA's if the car is equipped with disc brakes, or 10 inch Drum brakes.
They are all the same thing. No difference to them at all.
They all use the big ball joint.

There are some early, odd ball, 6 cylinder, drum brake, 73 A body cars, that came off the assembly line with 9 inch drum brakes.
Those cars had small ball joint upper control arms.
Chances, coming across one of those cars in this day and age, is pretty slim, but some members report that they have one, or at one time had one.
In my 30 years of professional wrenching, and going to the wrecking yards, i have only came across two, or three, of these stripped down models.

And another thing to clear up is if you have Kelsey Hayes, 4 piston disc brakes, on a 65-72 A body car, those A body's used the Small ball joint UCA.
Those 62-72 A body's all used the same UCA wether it was Drum brake, or Disc brake equipped.

Large ball joint UCA's started on the 73 A bodys, with disc brakes, or 10 inch drum brakes.

And another thing that i read from a poster is that if your doing a disc brake swap onto the A body you can use 73 up B body ball joints.
That is totally inacutate. Not true. False, wrong, information.
73 and up B body suspension changed with the 73 model year, and is a totally different design, and won't interchange with the A body cars.

You use 73-76 A body lower ball joints when doing the brake conversion.
Lower ball joints are the same thing for disc brakes, and 10 inch drum brakes, on the 73-76 cars.

Just some things that need to get clarified here, as i had some time to kill, before leaving the house for a medical appointment, so i made this reply.

I was relaying what I found on the "Big Block Dart" site. I never said that 10" drum brake 73 and up UCAs wouldn't work. All I said was that 73 and up A body disc brake control arms had the LBJ.
That's why I posted the links, so everyone could read it for themselves. I guess I should have said that the lower control arm is not an issue because you can keep that but you need the 73-76 lower control arm ball joint for the larger spindle. That's why I asked everyone to read the links.

PS - If 73 and up 10" drum brake upper control arms will also work in the swap then it leaves more options!!! Big Block Dark doesn't address the 10" drum brake upper control arms.
Treblig


Here is what the Big Block dart site says:


A-BODY DISC BRAKE CONVERSION

It's helpful to know the various chassis designations in order to find the correct parts.
Please refer to the Chassis Style page for more info

1. Upper Control Arms, from 1973-1976 A-Body Disc Brake Car. (single Piston Caliper only) The upper control arms are needed because the A-bodies were upgraded to the bigger B-body balljoints in 73, which means you need the later a-body arms to get the bigger balljoint. You can see the balljoint differences on the Steering Linkage Page

2. Spindles from 73-up A,B,E,F,J,M,R chassis disk brake car. Drum spindles don't work.
Note - the B,F,J,M,R spindle does have differences... Read A vs. B spindles for more info
3. Rotors and calipers - A-body rotors were 11" and were also used on many other cars. Some 77-79 B and 79-81 R bodies used an 11.75" rotor. Both rotors fit all spindles above. You do however need to use the caliper bracket that matches the rotor diameter. There are pin-type calipers and sliding calipers. The correct one must be used with the corresponding bracket. Most likely you'll find all your parts together on one car. The less-desirable pin-type calipers were used on the E-bodies, while most other cars had the slider style calipers.
4. Divider block and prop valve from a donor disc brake car.
5. New Front Brake Hoses (Rubber)
6. New Brake Pads & Bearings (you must know what make, model and year of the donor car)
7. New Master Cylinder, Disc & drum, use 73-76 A-Body, with or w/o power brakes
8. 4.5" bolt pattern front wheels.
9. New Upper Control Arm Bushings recommended
10. 73-76 Lower Ball Joints are necessary. The stock lower control arms can be retained.
11. From the donor car, remove the (2) lines that are attached to the master cylinder, and use them on
your car. it just easier to use these lines than to bend up your existing ones to work.



INSTALLATION:
1. Remove tension on Torsion Bars.
2. Replace the Upper Control Arms.
3. Replace Front Spindles with donor set, being careful not to mix up the left and right sides
(calipers to the front, steering arm/balljoint to the rear)
4. Install Proportion Valve in Line, in place of your old divider block
5. Replace Lower Ball Joints with 73-76 A-Body, (Larger size)
6. Install Rotors, Calipers and Pads
7. Replace Bearings, install cotter pin .
8. Re-Tighten Torsion Bar Adjuster to attain the proper ride height.
9. Install Master Cylinder. You will need a New Push-Rod Rubber Bushing, that holds the Pedal Push
Rod into the Rear of the Master Cylinder.
10. Have the front end Aligned -It's recommended you ask for the most caster possible while holding
factory camber settings.





As a final note, MANY of these cars interchanged alot of parts - almost everything was standardized from 73-up, so almost all the disc brake parts are interchangable, all based on rotor size 11" or 11.75"- for example, an '81 New Yorker 11.75" rotor can be used on a 73 Charger disc spindle with a caliper from a 73 Dart and a caliper adapter from a 77 Cordoba - the only consideration is that the caliper bracket must match the rotor size. You just need to think of the raw parts and not the whole car.

If you study through the tech pages, including the Moog Part # page, you'll find alot of similarities that will make your parts searches easier.

hemi71x said:

On the 73 -76 A body cars there is NO difference in UCA's if the car is equipped with disc brakes, or 10 inch Drum brakes.
They are all the same thing. No difference to them at all.
They all use the big ball joint.

There are some early, odd ball, 6 cylinder, drum brake, 73 A body cars, that came off the assembly line with 9 inch drum brakes.
Those cars had small ball joint upper control arms.
Chances, coming across one of those cars in this day and age, is pretty slim, but some members report that they have one, or at one time had one.
In my 30 years of professional wrenching, and going to the wrecking yards, i have only came across two, or three, of these stripped down models.

And another thing to clear up is if you have Kelsey Hayes, 4 piston disc brakes, on a 65-72 A body car, those A body's used the Small ball joint UCA.
Those 62-72 A body's all used the same UCA wether it was Drum brake, or Disc brake equipped.

Large ball joint UCA's started on the 73 A bodys, with disc brakes, or 10 inch drum brakes.

You use 73-76 A body lower ball joints when doing the brake conversion.
Lower ball joints are the same thing for disc brakes, and 10 inch drum brakes, on the 73-76 cars.

Click to expand...

Thanks for clarifying.

The Disc o Tech article has always been my go to reference.
http://www.moparaction.com/Tech/archive/disc-main.html