Big C Body Spindles Mounted On 1968 Dodge Charger?

[RIDGERACER383]

Hey guys.... Been a long time since I posted on here. Been buying parts for my 68 Charger and now looking to swap the front drums to disc. I have done a ton of research looking at different Mopar stock brake systems and found that the C Body spindles with the 11 3/4" rotors that are 1 1/4" thick discs with the matching wide mouth pin calipers looks like the top of the line when talking Mopar brake systems.

Has anybody put this big system on their Charger? I know I have to change the upper A arms and I should be able to use the C Body lower ball joint with my car. I have access to a set of cheap C Body spindles off a New Yorker. I think the C Body spindles might be the same height as the 73 up B bodies. New rotors, calipers and all the other stuff is available new which I'll get.

I've seen some people use A Body spindles and put big 11 3/4" and 1" thick rotors on but you have to use sleeves and spacers. I don't want that. Also the C Body uses bigger hardware to hold everything on the spindle.

What do you guys think?

[b5blue]

https://www.moparaction.com/tag/disc-o-tech/ 

[HPP]

Sorry to rain on your parade, but its much more involved than just swapping in ball joints and bolting it up.  Here is a detailed write up of such a conversion:

https://forum.e-bodies.org/wheels-tires-brakes-suspension-and-steering/12/-using-c-body-spindles-on-an-e-body-and-a-body-lcas-and-viper-calipers/58/


FWIW, you don't need sleeves and spacers to put 11.75x1 brake rotors on the appropriate disc spindles. All you need is 73+ ABEFJMR disc spindles.

[Nacho-RT74]

But using any other spindle than A or E body will change the ride height/suspension geometry

[Mike DC]

  
Agreed.  

You can do this the hard way but it's not necessary.  The 11.75 x 1.00" rotor makes a lot of sense and there's a lot of aftermarket support.  The extra 0.25" of rotor width on the C-bodies won't make a practical difference.  

It's taller diameter rotors that really help.  There is way more of a difference going up to 13" rotors, although that requires 17" wheels.  Think: grabbing a spinning disc at its outer edge versus grabbing it closer to the middle.  You get more leverage when the grab-point is farther out from the center.  Also better brake 'feel'.      

[HPP]

But using any other spindle than A or E body will change the ride height/suspension geometry

No, using the spindles I listed do not alter ride height, yes it does alter geometric angles.  In fact, the geometry is slightly improved by using the taller spindles and they are lighter weight than the A and E versions.

[Nacho-RT74]

of course the ride height can be adjusted se we could say "is not altered", but if it was posible to set the T bar at exactly same position, of course the ride height will be diff. Not saying is good or bad, it could be helpfull or not depending on application, but just it happens

[HPP]

It still would not be altered. The lower ball joint to the wheel mounting centerline is the same in all of these spindles. The extra height on the late B and FJMR body spindles is at the top of the spindle above the wheel mounting centerline. This extra height creates more angle in the upper control arm only. It has no impact on lower control arm position relative to the car even if the t-bar is installed in exactly the same spot.

The disco-tech article has been promoting a limited vision of disc brake interchange for decades based on one writer's conversation with one engineer. A vast majority of the hot rodding and racing world has opened up to new information and moved on.

[John_Kunkel]

The author of the original Disc-O-Tech article is a major asset to the Mopar community but he has opinions that many take as gospel. He has gone so far as to claim that the "tall spindle" is dangerous but that opinion has been rebuffed and has been proven to aid handling in some cases.

[RIDGERACER383]

Thanks for all the feedback. I know I have to change stuff up to make it work which I'm kool with. I plan on using the C Body lower ball joint also which is bigger and for now since I have access to a good pair, I'll use the C Body upper A arms too which has the bigger ball joint. I would like to take my Charger lower control arm and modify it with the C Body parts to accept big lower ball joint. We will see how that goes. I think the C Body A arm will fit on the charger.

I'm not starting this swap until I get my garage done in the fall but will have all the parts.

[Kern Dog]

The author of the original Disc-O-Tech article is a major asset to the Mopar community but he has opinions that many take as gospel. He has gone so far as to claim that the "tall spindle" is dangerous but that opinion has been rebuffed and has been proven to aid handling in some cases.

I agree.
Rick simply assumed without actually testing anything that the upper ball joint was in danger of "Over-angling" during full compression of the suspension, a condition that has since been proven to be false. Rick's ego won't let him admit the error.
The man is a wealth of knowledge so I try to overlook a few flubs.

[Mike DC]

Thanks for all the feedback. I know I have to change stuff up to make it work which I'm kool with. I plan on using the C Body lower ball joint also which is bigger and for now since I have access to a good pair, I'll use the C Body upper A arms too which has the bigger ball joint. I would like to take my Charger lower control arm and modify it with the C Body parts to accept big lower ball joint. We will see how that goes. I think the C Body A arm will fit on the charger.

I'm not starting this swap until I get my garage done in the fall but will have all the parts.

Why do you want bigger ball joints?  The B/E-body ones are not known for failing.  They are sized pretty well for the vehicle weight.   

[Nacho-RT74]

Well, I'm disagree, the ride heigh is altered. T bar needs to be more tensioned to get the same ride height you had previously ( or using A/E Body knuckles ). That's what indeed affects the geometry, raising the control arms. You can't affect one without the previous reason. The reason to get altered the geometry is precisely the diff height of the knuckle what needs to be reindexed. If wasn't because that, the geometry wouldn't be affected.

I'm not saying, once again, is good or bad, better or worst, I don't have suspension knowledgement to talk about that, but I know a bit of geometry. I began studying architecture at university, so I can see on my mind the diff position and what affects into the space.

[Nacho-RT74]

Thanks for all the feedback. I know I have to change stuff up to make it work which I'm kool with. I plan on using the C Body lower ball joint also which is bigger and for now since I have access to a good pair, I'll use the C Body upper A arms too which has the bigger ball joint. I would like to take my Charger lower control arm and modify it with the C Body parts to accept big lower ball joint. We will see how that goes. I think the C Body A arm will fit on the charger.

I'm not starting this swap until I get my garage done in the fall but will have all the parts.

Why do you want bigger ball joints?  The B/E-body ones are not known for failing.  They are sized pretty well for the vehicle weight.   

For the same reason ppl upgrade everything on their cars to just ride 200-500 km by year, to be able to say IT GOT xxxxxxx... LOL

[Nacho-RT74]

a crude draw on paint on how the knuckle/spindle height changes the ride height, requiring to readjust T bars, giving a diff control arms angles, and then that's the moment geometry changes at steering/supensions system, not before.


if I'm missing something, just let me know

[HPP]

Thanks for all the feedback. I know I have to change stuff up to make it work which I'm kool with. I plan on using the C Body lower ball joint also which is bigger and for now since I have access to a good pair, I'll use the C Body upper A arms too which has the bigger ball joint. I would like to take my Charger lower control arm and modify it with the C Body parts to accept big lower ball joint. We will see how that goes. I think the C Body A arm will fit on the charger.

I'm not starting this swap until I get my garage done in the fall but will have all the parts.

Great, go for it. Some considerations as you go along the way;

1. For racers, weight is everything. They do not pick bigger, heavier components unless the job dictates it. Yes, back in the day the NASCAR boys used C body ball joints. That's because they were playing bumper tag at 180 mph.
2. The stock B body ball joint has been adapted to and used by every suspension component manufacturer for short and mid track racing until this day. The thing is bullet proof and is available is stock, +1 and +2 pivot heights.
3. Changing all the arms will change geometry. Make sure you are not introducing changes that are going to be negatives.
 A. If you use the C body lower, you will have to use the B body pivot. C body t-bar hexes are larger and will require you either use the B body pivot or  change the anchor to C body size, thus requiring custom torsion bars. Not sure if a B pivot will fit in a C arm. Never looked, so it might be possible.
 B. I'd highly recommend using tubular uppers to gain improved geometry and additional caster, even if C body arms are free. The biggest shortcoming of mopar's design in the caster/camber inter-dependance. C body parts will not improve this.

a crude draw on paint on how the knuckle/spindle height changes the ride height, requiring to readjust T bars, giving a diff control arms angles, and then that's the moment geometry changes at steering/supensions system, not before.


if I'm missing something, just let me know

Yes, you are missing a key point. Your two drawings on the right show drop spindles.  Drop spindles move the wheel mounting centerline up realtive to the rest of the spindle. The taller Mopar spindles are like the drawing on the left, only with upper control arm slightly raised.  This is the key of what I'm trying to convey, the dimensions from the lower ball joint mount to the wheel mounting center line are IDENTICAL among all the ABEFJMR spindles, all years, disc brake, drum brake, or tall versions. Only the lower control arm determines ride height. Identical dimension produce identical ride heights. The extra 3/8 of an inch is all in the upper part of the spindle, above the wheel mounting centerline, which only changes the upper arm angle.  Now the change in this angle impacts other geometric motion and as a result, performance, but it does not change the ride height.

[Nacho-RT74]

OOOOH... OK... so the diff is just between wheel mounting center to top ball joint, and not to bottom ball joint being the total height the difference?

I have allways thought the diff was againts the bottom ball joint height, being a higher wheel mount and the distance between top and bottom ball joints remaint the same! That's why I draw it like that!

[b5blue]

  I'm running the factory big rotors set up outlined in the link I posted. B body Mopar is famous for rugged durability and ease of repair/service. Personally I would pass on all the R/D-time/expense even with free parts. I've seen others spiraling down the rabbit hole of modifications that postpone getting to use the car being built.
 Now as a hobby it CAN be all about the "build" more than the "driving" so please post lots of pics with details if you do go this route.   Best of luck!

[RIDGERACER383]

I found these today that should help me alot with dialing everything in.

[RIDGERACER383]

Anybody running those control arms?

[pro451bee]

Those control arms look scary to me.

[Mike DC]

  

Those control arms look scary to me. Shocked

Those actually aren't bad.  Racers use UCAs like that on a regular basis.  UCAs don't see big vertical loads the way lower arms do.  

And notice that there is no pivoting joint on the far side of the ball joint, only the near side.  It doesn't have as much room to flop around on those joints as it might look.  



But for a street car?  I dunno.  I'd still rather just figure out the ideal dimensions and get a solid set of arms made.  All those threaded pivot points add extra weight and give it room to loosen up or wiggle out of alignment over time.  Going a few hundred miles per year on tracks is not like running 50,000 street miles.    

[RIDGERACER383]

I think you are right. For regular driving I think I would be constantly adjusting those things and they may come loose often from regular driving.

[Mike DC]

  
A better set of UCA dimensions is not rocket science.  Take a stock UCA, move the ball joint backwards (towards the firewall) by about 1/2".  And maybe move the BJ inwards (towards the engine) by 1/4" or so.  That would do it.  

The stock alignment cams offer plenty of adjustment if the UCA's raw dimensions are in the ballpark.  We struggle with the stock arms today because we're trying to put the caster 3-4 whole degrees away from where the factory intended.  

[Kern Dog]

Those control arms look scary to me.

Same here. For a race car ? Yeah, okay. For a street car that will see some rough roads and bumps? I'll pass. The multiple bolts and nuts seem to be way too busy for me...more things to break!