Upper control arm ball joint spindles not long enough on disc brake conversion

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Kolbjorn

Kolbjorn

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Hey there,

I've been working on converting my manual drums to power disc in my 71 Valiant and everything has gone together fine up until now.

The kit I used is the Pirate Jack Front Disc Conversion for small bolt pattern A body. The problem that I've ran into is that the spindle on the upper control arm ball joint isn't long enough for the castle nut to thread properly. I need about a half in, maybe a little less for the castle nut to thread enough to fit a cotter pin through. Does anyone have any ideas? I thought about using a stover nut or something instead, but that doesn't seem right.

Ideally there would be upper ball joints for stock 71 upper arms that have a slightly longer thread to allow the castle nut to properly fit.

Any help or ideas would be appreciated! Thanks
 
I’m pretty sure there’s two different sizes of upper ball joints, I ran into a similar problem doing my front disc swap. I ended up just ordering some tubular 73+ UCAs that came with the larger ball joint.
 
So I can't afford new later model upper arms, but from that kit DoctorDiff had in the thread hemi71 posted it comes with flange nuts instead of castle nuts. If I loctite those flange nuts and torque them down would that be safe as using castle nuts? Am I being paranoid? Does anyone have any experience using that kit instead of switching to newer arms? Thanks yall.
 
Kolbjorn said:
So I can't afford new later model upper arms, but from that kit DoctorDiff had in the thread hemi71 posted it comes with flange nuts instead of castle nuts. If I loctite those flange nuts and torque them down would that be safe as using castle nuts? Am I being paranoid? Does anyone have any experience using that kit instead of switching to newer arms? Thanks yall.
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Not sure if it helps but I got longer spindles. I think I still have the package. I can take a pix of it should that help you at all. It would at least give you make and part number if applicable?
 
Sublime one said:
Not sure if it helps but I got longer spindles. I think I still have the package. I can take a pix of it should that help you at all. It would at least give you make and part number if applicable?
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That would be great! Thanks
 
Syleng1 said:
There is no safe substitute for castle nuts and cotter Pins. Period
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Yeah, your probably right. I'm just having a hard time finding shorter castle nuts that will clear the little threads available in the right size. But I think I will make sure that I get a castle nut on there one way or the other! Thank you
 
I'm confused. are you saying there isn't enough thread, on the end of the ball stud, showing to thread the nut on when shoved thru the tapered hole in the spindle?
 
rustycowll69 said:
I'm confused. are you saying there isn't enough thread, on the end of the ball stud, showing to thread the nut on when shoved thru the tapered hole in the spindle?
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Sorry, yes. Your right that is my problem right now. the stud on my oe balljoint isn't long enough to properly thread the castle nut on
 
Just mill, grind, down the the bottom side of the spindle where the stud goes thru.
Easy, peasy.
Don't keep making a mountain out of a mole hill.
Don't worry about it, loose any sleep over it.
Spindle is way thick enough to allow a modification.
Discussed in the "link" to the earlier reply.
 
though I can't remember the taper ratio, offhand, I remember that it is a common ratio, like 3/4" per foot. or 1in per foot.
if you have some dial calipers you can measure the big end diameter(decimal inches) and the small end diameter(decimal inches), & find the difference. Take that difference and divide it by the thickness of the taper hole(in inches) in the knuckle, then equate it to "x""/12", and solve for "x". Once you have that, you can beg, borrow, rent the correct tapered reamer and ream it out SLIGHTLY bigger. It should not take very much to drop the taper in there. You do not want to expose all the threads, probably one or two threads should be below the nut contacting surface/hidden when fully inserted and torqued to spec.
 
The issue you raise is definitely particular to that Pirate Jack kit. I just recently worked through the same conversion with that kit. And it has those locking nuts. You use those with the sleeves for the upper ball joints. I didn’t like the look of that so I just bought new UCAs with the bigger ball joints. A few other guys have used that Pirate Jack kit on FABO and they haven’t had any problems with that lock nut that I have heard. You just have to get that nut on far enough to be flush with the end of the ball joint stud when tightened.
 
As promised here is a pix for the ones I used. Official Disclaimer, these may or may not be the ones you want but gives you manufacturers name and some official part numbers! Good luck

E240D422-BEAA-4B9E-80FA-EC3EEF273793.jpeg
 
though I, personally, prefer castellated nuts with cotter pins, I've noticed that later mopars have self-locking nuts on their ball joints, ball studs. That being said, I don't know that I would feel confident about re-using self-locking nuts, whereas reusing castellated nuts is not a problem.
 
Sublime one said:
As promised here is a pix for the ones I used. Official Disclaimer, these may or may not be the ones you want but gives you manufacturers name and some official part numbers! Good luck

View attachment 1715543932
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These look like they'd be perfect! It says 68-89 Chrysler/Plymouth... so I assume they would fit my arms. Do you if the upper arms you put these into are the pre 73 smaller style or are they the bigger style ball joints?

Thanks for the help yall!
 
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