crznZ06

I'm replacing the lower control arms on my car, and got to the point where I'm putting the knuckle and the arm together. No matter how tightly I tighten the nut on the stud, the stud keeps turning with the nut. This is with me holding the stud with an allen key.

The last time I did this, there was a point where I got enough torque on the stud such that it stopped turning with the nut. Then I was able to go through the whole torque sequence. What gives this time? What should I do? Thanks guys!

davidfarmer

Assuming the threads weren't damage during removal (if you hammer them out, make sure you nut is still on protecting the threads), then I can't imagine. I'd try another nut (it's a common size on the car, "borrow" one from elsewhere).

They usually go together easily, so I can only imagine it is a damage or cross-thread situation.

mousecatcher

just torque with hex key in place. use a crow's foot and adjust the torque value appropriately. FYI, for C6 you need to use a brand new nut. Don't know about C5.

crznZ06

Hi David,

The threads are perfect on the stud. Here's some more information:
1) When the knuckle is on the control arm, the threads go below the mating surface of the knuckle (i.e. the nut isn't bottoming on the knuckle before snugging the two together);

2) I'm using brand new OEM fasteners;

3) The new ball joint stud and the knuckle have more play between them than the old ball joint stud and the knuckle.

The last one is what scares me. I have a sneaking suspicion that the ball joint stud on the new control arm is too small or that the knuckle is out of round or stretched out. Has anyone seen this happen?

Thanks again!

exracer28

Try placing a jack under the control arm and jacking up to push the taper into the spindle.

crznZ06

Exracer28,

Thanks for your reply, but I already did that.

Anyone else? Help please!

gkmccready

This would be the opposite of the upright opening up. Are you sure your new fasteners are correct?

crznZ06

Yes, the new fasteners are correct. They look identical to the pieces that came off the car, less the grime.

mousecatcher

why don't you try (or what don't you like about) my crow's foot suggestion?

crznZ06

Mousecatcher,

I'm afraid that if there isn't a positive or tight fit between the ball joint stud and the spindle, there will be enough play in the system such that either the stud or the spindle could fail.

mousecatcher

it does indeed sound like that's the real problem here.

davidfarmer

you should be able to measure the diameter of the stud, the threads, and thread length and see if it matches your old setup. If not, then somehow you must have gotten a mis-threaded ball-joint.

So it sounds like the nut is bottoming out on the stud threads, but the spindle is still loose on the ball joint??? Can you put washers on top of the spindle, then put the nut on, to take up the extra space???? If I'm not picturing this right.....maybe draw a picture????

I've personally never had anything like this happen....congratulations on finding a new problem for us all to worry about

TedDBere

Trying to install the left side on the right side upside down?

crznZ06

David,

You have it almost correct. The lowest part of the threads is still BELOW the surface of the spindle that the nut contacts. However, when I tighten the nut down, while holding the stud in place with an allen key, I never get to the point where the stud stops wanting to turn with the nut, so I can't get to the point where I can start going through the correct torque sequence.

My guess is that my knuckle is either out of round, or has opened up. It could be that my new control arm has a ball joint that is undersized, but the knuckle is cheaper than the control arm, so I ordered a new knuckle this morning, and I'm going to try and see if a new knuckle improves the fit.

I thought about throwing a washer under the nut, but there's enough play between the ball joint stud and spindle such that I don't think there would be a postive fit there. I don't trust my luck much, so I didn't want to wing it.

Thanks.

Kanmer

Thats my first thought. Something is upside down.

ghoffman

I use a free running nut on an oiled thread with a Nordlock. It never loosens, except when I want it to, but most guys want a Nyloc or smash nut that detracts from getting adequate preload into the stud.

crznZ06

Hi Gary,

Thanks for the information on the Nordlock washers, but regardless of the washers not allowing the nut to back off, isn't the the "system's" load bearing capacity dependent on a snug fit between the taper of the spindle and the taper of the ball joint stud? In other words, even though the nut is torqued down properly, if there's still space between the tapered portion of the ball joint stud and the spindle, the load will be on the shank portion of the ball joint (the threaded portion) instead of the main load bearing surface (the tapered portion) that fits inside the spindle, right?

Thanks for your input!

crznZ06

^^^

96CollectorSport

I've already had to take a long prybar and pull down on the upper a-arm to get the not to stob moving and if that doesn't work you way have to jack up from the bottom of the lower a-arm and pry down from on top of the upper a-arm, this way you will get the most friction possible on the ball joint shaft. If that doesn't work I would say that there is something wrong with the ID of the knuckle or the OD of the ball joint.