w123 upper control arm dos and donts? - PeachParts Mercedes-Benz Forum

sleepstar · #1 10-19-2013, 02:53 PM

gonna replace the UCAs on my 300D. looked at the DIY faq but it goes off on a tangent about brake rotors or something.

is the safest way to work around the spring to keep a jackstand under the LCA, and then jack up the knuckle when bolting to the balljoint?

am i correct in understanding that the torsion bar bolt and the ball joint can be torqued to spec with the car in the air, and that the UCA to body bolt is the one that must be torqued with the wheels on the ground?

TIA

ichris93 · #2 10-19-2013, 04:48 PM

Quote:

Originally Posted by sleepstar

gonna replace the UCAs on my 300D. looked at the DIY faq but it goes off on a tangent about brake rotors or something.

is the safest way to work around the spring to keep a jackstand under the LCA, and then jack up the knuckle when bolting to the balljoint?

am i correct in understanding that the torsion bar bolt and the ball joint can be torqued to spec with the car in the air, and that the UCA to body bolt is the one that must be torqued with the wheels on the ground?

TIA

I removed the spring when I rebuilt my front end.

sleepstar · #3 10-19-2013, 06:39 PM

Quote:

Originally Posted by ichris93

I removed the spring when I rebuilt my front end.

wish I could, but i dont have a spring compressor and I'm only doing the UCA, not the lowers.

Diesel911 · #4 10-19-2013, 07:41 PM

If is best when you torque the Bolt that Goes through the Fender Well if the Wheels are on the Ground. That clamps the Rubber Bushing in sort of a neutral position with no flexing of the Bushing. (The same with the Lower Control Arm Bushings.)

Next best would be if you put it on Jack Stands keep both sides at the same level and not raised any higher needed to get the Wheels off.

What do you plan to use to detach the Upper Ball Joint on the UCA from the Knuckle?

The tips of the Sway Bar are often rusted thin to the extent they sometimes break off. If the Tip breaks off there is 2 possible repairs for that.

vstech · #5 10-19-2013, 08:35 PM

the upper control arm is not under spring tension. you can safely remove them without doing anything to the spring. assemble everything tight except the inner bolt, just leave it loose, until the car is sitting back on it's tires, then tighten it up.
get a good ratchet strap to assist moving the spindle around to get the torsion bar connected.

be sure the shock absorber stays connected, but the guide rod is keeping everything stable.

toomany MBZ · #6 10-19-2013, 08:40 PM

UCA Install

See post #4.

vstech · #7 10-19-2013, 08:45 PM

Quote:

Originally Posted by sleepstar

gonna replace the UCAs on my 300D. looked at the DIY faq but it goes off on a tangent about brake rotors or something.

PeachPartsWiki: Upper Ball Joint Replacement

sleepstar · #8 10-19-2013, 08:47 PM

thanks all

i've examined the sway bar visually and it looks OK with no rust (california car since 1981) but of course something could be hidden when i get it apart. the current UCAs were installed about 70k and 7 years ago.

oh and i have a ball joint separator. going to do the tie rods after the UCAs.

cooljjay · #9 10-19-2013, 09:50 PM

Are you sure the uca are bad? 70k and 7 years use seems kinda young for replacements unless they were uro quality.....I have the original uca's on my car with 35 years on them....they look fine....

sleepstar · #10 10-19-2013, 10:06 PM

both sides make all kinds of bad noises and the ball joint boots are completely torn. not sure what they are. the shop the PO took the car to usually did OK work, although they did put A1 Cardone calipers on.

vstech · #11 10-19-2013, 10:10 PM

... noises are more often caused by LOWER ball joints...

sleepstar · #12 10-19-2013, 10:19 PM

yes . i'm having the lowers done at a shop because i dont have the tools necessary to do them

winmutt · #13 10-19-2013, 10:22 PM

Have a helper and have some leverage. I seem to remember needing a good 4 ft or so of leverage. Some times I think it even took multiple pressures. Watch your fingers!

vstech · #14 10-19-2013, 10:26 PM

Quote:

Originally Posted by sleepstar

yes . i'm having the lowers done at a shop because i dont have the tools necessary to do them

you can save some SIGNIFICANT money doing the lower's yourself... I and others rent the tools needed to pull the spindle for lower ball joint removal..

ichris93 · #15 10-19-2013, 11:13 PM

Quote:

Originally Posted by vstech

you can save some SIGNIFICANT money doing the lower's yourself... I and others rent the tools needed to pull the spindle for lower ball joint removal..

I removed the spindles and brought only the spindles somewhere. Still cost me $45 a piece to remove and have no ones installed