300CD: Tightening the 22mm nut on each steering knuckle ball joint - PeachParts Mercedes-Benz Forum

5cylinder · #1 12-26-2014, 03:04 PM

Howdy-

I'm nearing completion of a complete front end rebuild on my 1985 300CD. A wee bit brain dead at this point, so reaching out for some advice.

I understand that 80Nm of torque should be applied to the 22mm nut on each steering knuckle ball joint.

Of course, as one is applying the torque, the ball joint stem/pin spins eventually and no progress is made. How to remedy this?

I was thinking that I had read somewhere that the wheel+tire must be installed and the vehicle on the ground (not on jack stands and off the ground) in order to apply the 80Nm of torque. Here's my concern: With the shock and spring installed, will there be adequate space for my torque wrench? I have my doubts about this.

And for anyone wondering: There is no hex key port in the top of the (Lemforder) ball joint stem/pin.

So, any advice as to how to hold the ball joint stem/pin from moving while applying the torque?

Thanks for any help to salvage my brain at this point.

Dan Stokes · #2 12-26-2014, 04:06 PM

I've encountered this sort of issue several times over the years and there are several possible cures. Generic things to try:

1) Assuming it a lower joint, put the jackstand right under the ball joint to force the taper into the eye. Sometimes works.

2) Smack heartily on the bottom of the joint - I use a lead hammer but if you don't have one use a block of wood (hardwood like oak preferred) and a BFH. Use care not to mess up the Zerk fitting hole or get junk into it, if so fitted.

3) Shanghai an unwilling accomplice to pry the control arm onto the taper - this one often gets the job done.

General advice - don't fret TOO much over the torque. Most shops will pull this connection up with an impact. Besides, if there's a cotter pin, you'll have to move the nut to the next slot anyhow so the torque will be higher than the spec. Sadly but not surprisingly, my Haynes manual shows nothing on this so I don't have details on this particular installation.

Dan

5cylinder · #3 12-26-2014, 04:22 PM

Yes, I am referring to the lower ball joint (see two attached pictures - from the right side).

I had placed a jack under the steering knuckle and propped it up enough (applied enough pressure) to get the 22mm nut as far as it is as shown in the pictures (until the ball joint's stem/pin started spinning). I wasn't sure if I should keep raising the jack to place more pressure - and possibly damage anything?

toomany MBZ · #4 12-26-2014, 05:41 PM

The FSM mentions to use a spacer to "set" the joint.

The horrible pic may help, but use the larger, 8mm end of the self made tool.

I did this on an upper control arm ball joint using the smaller 6mm side. Well, I used an open end wrench of the proper dimensions.

5cylinder · #5 12-26-2014, 06:46 PM

Yes, I have the FSM and I reviewed that picture and just laughed. Maybe I'm just slow but the picture didn't mean all that much to me.

I ended up solving my problem by using a vise (didn't have a c-clamp) to essentially carefully squeeze the two arms together. It worked.
Thanks-

toomany MBZ · #6 12-26-2014, 07:05 PM

Glad to hear it.

jay_bob · #7 12-26-2014, 07:16 PM

I had that happen to me when replacing my spindle on my W210 recently.

I ended up using the floor jack to force the joint together, to create enough friction between the arm and the stem, so that when you snug up the nut the stem does not spin.

Can't understand why they don't put an Allen key hole on these stems, it would make it sooo much easier....

5cylinder · #8 12-26-2014, 07:58 PM

Quote:

Originally Posted by jay_bob

I had that happen to me when replacing my spindle on my W210 recently.

I ended up using the floor jack to force the joint together, to create enough friction between the arm and the stem, so that when you snug up the nut the stem does not spin.

Can't understand why they don't put an Allen key hole on these stems, it would make it sooo much easier....

I used my jack on both sides and I got things shoved up a fair amount and still had the turning. I didn't have the guts to keep jacking. Either that or I was having a moment of cautious intelligence.

No Allen key hole?! 'Cause they LOVE to torture us! I'm in the mood to beat the stuffin' outta whoever is making these ball joints and refusing the Allen key hole! The dang tie rods have the Allen key hole. What gives??? Sheesh.

jay_bob · #9 12-26-2014, 08:29 PM

Make sure that the force you are applying is directed towards making the stem slide further into the arm. If you are just pushing the stem and the arm at the same rate then the tapered part of the stem can't get pushed into the arm far enough to grab on.

You might have to use a piece of wood to hold back one piece while pushing on the other.