Idler arm bolt and castle nut

[chargerdon]

Some help please!!

Found my idler arm would pivot in its frame allowing the center link bar to move up and down by at least an inch.   

So decided to tighten the bolt that holds it and was able to do so enough to stop it from pivoting (about 180 degrees of turn.    Now my problem..   First off looking at the 74 service manual pictures for carline J, it does not show any information on the idler arm bolt...only on the castle nut at the link bar.   So not sure what should be there as there is no castle nut AND the bolt if inserted from the bottom pointing up and its 13/16 and the NON castle nut at the top took a 7/8 wrench.    Surely this cant be right ??    Again in the service manual for carlines P, D, C, Y it shows the bolt inserted from the top down, and a castle nut on it...   jHMMM   

Looking on Classic Industries for Challenger line, their picture for part number K7041B Idler arm kit that shows a Bolt some bushing like spacers a std washer and a standard nut.   It also shows a castle nut, but im guessing thats for the link bar side.    It does not give any installation instructions or bolt specifications.   

So now i dont know WHAT exactly should be there...maybe mine is correct ??   

[chargerdon]

Ok, found a Youtube video for replacing the Idler arm on a 68 Charger which is a B body, but B Body and E body is shown to use the same part number for replacement.   In this video the mechanic found the same situation.   I.e Bolt going in from the bottom but the Nut on top was a castle nut with cotter pin.    The replacement he had showed the top Nut to be Non castle 7/8 and did NOT come with cotter pin.

The mechanic said that the Nut was "oblong" so that it tightened and as such should not work loose.   He didn't like that idea so put in the same old bolt and castle nut and cotter pin as he felt "safer" with that method.    Not feeling comfortable, wondering whether it really should have a Bolt and castle nut, or whether the slop in mine was because it wasn't tightened enough originally, or whether the built in cushions have worn, and with finding a Moog brand for it on Amazon for only $28.95 and free shipping with Amazon Prime, i went ahead and ordered the Moog replacement.   It came in this afternoon and i examined it.   One, it comes with a nut not a castle nut, and the bold head is 13/16 and the Nut head is 7/8.   Go Figure...  still wish it had a castle nut...   doesnt make sense to me but ill install it as is.   

[Brads70]

Is this the video you found?  I'd agree I'd use the original bolt, I like the cotter pin design better.
The new designs " lock nut" if you will is just a slight crush on the nut so it's an interference fit, it likely will never cause an issue though. Pretty common these days....

[chargerdon]

yep, thats the youtube i found.