Separating Upper Control Arm from Spindle - Nut Spins!
 

Hi,

I tried changing my lower ball joints (1984 300CD 123 chassis) earlier this morning. I took everything off and the last thing I needed to undo was the spindle from the upper control arm ball joint. The nut that holds the spindle to the upper control arm joint was extremely tight. After pouring blaster all over it, I gave it way too much pressure and broke something (I think). Now, the nut spins with the bolt. When I turn the nut, it spins the entire ball joint. Does this mean that my ball joint is busted? What did I do wrong? Huge failure. Not sure how I can take the nut off now to remove the spindle from the upper joint. Has anyone had trouble with this bolt? Is there any way to fix it now?

Any help would be truly appreciated. I'm speechless. I was so close. Thank you.

I don't think you broke anything. The ball joint will spin with the nut unless the joint is firmly pressed to the spindle. I didn't have the problem taking it off, but did have it putting it on. I used a large C-clamp to hold the joint and spindle together while turning the nut. If the joint and spindle are pressed hard enough together, the joint will not turn with the nut. If I'm understanding the situation correctly, I don't think you are in panic land at all.:o

My upper control arm misadventures were extensive. If you didn't need a sawzall to get the arm off the frame, you're doin' OK.

Thanks, Bodhi. That makes sense. I'll try a clamp tomorrow and see where it goes. Just to clarify though, the control arm is still on the car. I was hoping that I wouldn't need to change it given all the stories I hear about how tough it is to get the bolt connecting it to the chassis off. All I wanted to do was separate the spindle from the upper ball joint. I hope the clamp works. If not, I'm guessing my last option is to cut the bolt and replace the uca?

The end of the bolt should have an allen keyway to hold it steady while you remove the nut.

Danny

Thanks, Danny. I called my friend at the Benz dealership out here and he mentioned something about an Allen keyway. I looking for it, but don't see it. I'm expecting to see it in the center of the bolt (i.e., like the keyway on the steering box adjusting bolt). My lower ball joint bolts are right here in front of me and they don't have a keyway in the center. What am I missing? Thanks again, guys.

Mine did not, but that may have changed between '78 and '84 of course. That would make it a heck of a lot easier, that's for sure.
Alex, if the ball joint isn't cracked or leaking and the bushings look good, no need to replace or remove the arm. I do think you need to replace the nut on it but someone may correct me on that. I believe it is a self-locking nut and thus should be renewed on principle. Check for the allen fitting on the bottom of the bolt as Danny mentioned ... if it's there, all you have to do is hold it with an allen wrench while you turn the nut ... super easy.:) If not, try the C-clamp, or have a friend squeeze the joint and spindle together while you turn the nut.

I don't think you're missing anything ... my 123's UCAs don't not have the allen keyway. It kind of threw me for a loop too. You just need a third arm or a clamp of some sort, I'll bet it'll come off for you.:cool:

If there is no allen, you may be able to remove by applying pressure between the two. The pic concerns putting things back together.

Thanks, all. I'm going to cover the nut in blaster and let it sit overnight. I'll pick up some clamps in the morning and try again with some help from a blowtorch. Of course, I'll do all this after I make sure there's no Allen keyway. I'll report back. Thanks again.

Make sure you don't melt the rubber boot with the blowtorch.

Some do, some don't. It is sometimes possible to grind a screwdriver slot into the end of the stud to accomplish the same thing as the allen recess.

You should not have to use too much heat on the Nut; a Propane Tourch would be enough.

If your other efforts do not work you might try careful use of a Nut Splitter.

Thanks, guys.

Bodhi, one question about using the clamp. I'm thinking about how it would work. I feel like if I put a clamp on, it would attach to the area of the spindle right next to the stuck nut. With the clamp on, there won't be room to get to the nut with a ratchet. I'm picturing the clamp bolting onto right next to nut, where else would it clamp onto? If this is the case, how can I get the nut off?

If I don't get anywhere with the clamp and my buddy holding the spindle and the control arm together, I'll try the nut splitter. Diesel911, is the nut splitter just to break the nut off? And then I would need a new nut? Is that how it would work? Sounds promising.

Thanks again.

Friction!
 

With the front of the vehicle supported at the jack points let the front suspension hang down. Use either a piece of 4" X 4" or something similar and a piece of 2" X 6”. Place the 2X6 flat up inside the wheel well above the UCA, stand a piece of 4X4 on top of the UCA end or on top of the torsion bar where it connects to the UCA.

Use a jack under the LCA/spindle to lift the suspension upwards. When the suspension raises enough the wood blocking will stop upward movement and cause the weight of the front end to exert downward pressure on the UCA taper and force it into the spindle's tapered hole. This will increase the friction fit between these two parts and will allow you to remove the UCA nut. If you heat the nut, not red hot but just too hot to leave your finger on it will help removing the nut.

In the future with the weight if the car on the suspension loosen and remove the nut completely, then spray it with lube and put it on a few threads, then you can use either a puller or hammers to separate the UCA taper from the spindles upper end, the nut will keep things from flying apart when they separate but it will come completely off easily, that way you don't get caught trying to remove a tight nut from a spinning taper!

You can also use a long pry bar to exert downward pressure on the UCA with some support under the LCA/spindle. The pry bar goes over the torsion bar and tip of the prybar goes below the UCA where the bolt goes thru it and and you can hang on that forcing the taper into the spindle as someone turns the nut. You need a good pry bar at least 4' long, I have a 6' long 1 1/2" hex spud bar that does this trick well. Good luck!

I tried everything today and the nut just doesn't want to come off. The nut splitter I bought didn't even fit over the nut because of the spindle arm. I'm close to giving up. I'm thinking I may have damaged the spindle or the upper ball joint tapers when I tried to rip the nut off and that's why it's spinning so freely. I tried putting leverage on it with a prybar like Billybob mentioned, but nothing. I even tried a steel pipe. The nut still spins. Not sure what else to do but to take it to someone to torch the thing off. Entire weekend down the tubes.