W126 Upper Control Arm Installation - PeachParts Mercedes-Benz Forum

R Leo · #1 01-09-2006, 03:19 PM

I'm over the hump on the Sybill the SDL's frontend job and am finally reassembling her now. But, I ran into a bit of a problem getting the upper control arm (UCA) pivot bolts fully installed (through both holes in the body) with the new rubber sway arm bushings in place at the outer ends of the UCAs. The new rubber isn't compressed as much as the OE piece and it cants the UCA forward, keeping the pivot bolt from aligning with the reamost hole in the body.

It didn't lack much to align and be able to push the bolt home but I was stumped. For about 3 hours, I tried prying and pulling on the end of the arm to get the bolt to align with the holes but, had no luck. The FSM was no help either ...it simply says reinstall the control arm or some other useless nonsense. I even searched the Forum for some advice...no luck! It seems that nobody had the problem that I was experiencing.

Finally. I realized that if I clamped a vice-grip onto the head of the UCA pivot bolt, I might have enough leverage to be able to get the bolt to align with the hole and I was right! It took 2 seconds to do the left side and 3 to do the right.

I hope this saves someone some time.

MattBelliveau · #2 01-09-2006, 03:31 PM

I did mine on my 300d, and I'd imagine it would be similar to yours. In order to get it all together, I hade to split one of the bushings (the one between the UCA and the inside of the sway bar). I put the bold throught the pivot (body) first. I then had to put some pressure on the CA, towards the front of the car. That allowed me enough room to get the bushing onto the sway bar. I couldn't get it to work any other way.

R Leo · #3 01-09-2006, 03:41 PM

Quote:

Originally Posted by MattBelliveau

I did mine on my 300d, and I'd imagine it would be similar to yours.

The front suspension on the W123 and W126 are almost identical.

MattBelliveau · #4 01-09-2006, 03:53 PM

The compresion of the UCA against the sway bar should be enough to hold that bushing in place. I figure that if it gets to the point where splitting the bushing would cause it to pop out down the line, then the Control arm needs replaced anyway. Good luck!

R Leo · #5 01-09-2006, 04:03 PM

Fortunately, I was able to install mine without splitting the bushings. I put the rear sway bushing on, located the UCA on the sway arm and installed the front bushing then started the restraining bolt. Next, I pushed the pivot bolt all the way through the pivot hole and the UCA bushing until it hit the rear side of the UCA mount. Then, I snugged the sway bushing restraining bolt/washer assy. until it was tight, compressing the bushings and pulling the outer end of the UCA aft. Finally, I clamped a vice-grip onto the head of the UCA pivot bolt and used it to angle the bolt enough to be able to push it through the aft pivot hole.

Brian Carlton · #6 01-09-2006, 06:05 PM

Quote:

Originally Posted by R Leo

Fortunately, I was able to install mine without splitting the bushings. I put the rear sway bushing on, located the UCA on the sway arm and installed the front bushing then started the restraining bolt. Next, I pushed the pivot bolt all the way through the pivot hole and the UCA bushing until it hit the rear side of the UCA mount. Then, I snugged the sway bushing restraining bolt/washer assy. until it was tight, compressing the bushings and pulling the outer end of the UCA aft. Finally, I clamped a vice-grip onto the head of the UCA pivot bolt and used it to angle the bolt enough to be able to push it through the aft pivot hole.

OK, I'm thorougly confused.

From memory, on the driver's side, the bolt starts out in no-man's-land below the fuse box. You can barely get it started with your fingertips. Once it goes into the UCA and on through, it hits the inside of the sheet metal on the forward UCA mount. So, it won't go through because it's not lined up.

But, you can see the very end of the bolt if you look through the hole on the forward side. The bolt will be higher or lower or closer to you or further away from you..........correct?

Then just take a mallet and smack the UCA in the desired direction to line up the bolt with the hole. Then just tap the bolt head lightly and it goes right in.

I had no issue with this. The hardest part is getting your big paws down below the fuse box and getting the bolt started into the rear mount and then into the UCA.

SD Blue · #7 01-09-2006, 06:40 PM

Hmmm....., It seems there is a difference from which side to start the bolt. On mine the bolt head was toward the engine compartment. Brian, yours sounds like the bolt head is toward the firewall. As far as which is correct, and it may not matter, is the question.

It probably depends on what you want to fish for when you've dropped it half a dozen times in that area under the fuse box.

Brian Carlton · #8 01-09-2006, 06:46 PM

Quote:

Originally Posted by SD Blue

Hmmm....., It seems there is a difference from which side to start the bolt. On mine the bolt head was toward the engine compartment. Brian, yours sounds like the bolt head is toward the firewall. As far as which is correct, and it may not matter, is the question.

It probably depends on what you want to fish for when you've dropped it half a dozen times in that area under the fuse box.

I really need to double check it........but, from memory, I started the bolt from the firewall side and could see the tail end of the bolt on the forward side.

Now, if Randy started the bolt on the forward side, he could never see the tail end of the bolt on the firewall side and would be there for three hours trying to find the hole.

You'd think, at his age, he'd be better at that.

SD Blue · #9 01-09-2006, 06:57 PM

Quote:

Originally Posted by Brian Carlton

You'd think, at his age, he'd be better at that.

Maybe that was the problem all along!

Brian Carlton · #10 01-09-2006, 06:59 PM

Quote:

Originally Posted by SD Blue

Maybe that was the problem all along!

Gee........for his sake..........I sure hope not.

R Leo · #11 01-09-2006, 07:51 PM

Quote:

Originally Posted by Brian Carlton

You'd think, at his age, he'd be better at that.

I resemble that remark...

FWIW, the bolt on the left side had originally been installed with the head aft. I saw absolutely no reason to fight with the brake booster, brake lines, electrical lines and gawd knows what else trying to get the bolt in there and chose to reinstall it instead, with the head toward the front and use a spring-loaded grapple to locate the nut on the end of the bolt after I got it through all the holes.

Remember, the reason that the holes wouldn't line up was because the UCA was canted forward slightly by the thickness of the sway arm bushings.

MikeTangas · #12 01-09-2006, 09:12 PM

I think I found it easier to mount to the tower, then muscle the end onto the sway bar. Still took a bit of ooomph but went along quickly.

Brian Carlton · #13 01-09-2006, 10:06 PM

Quote:

Originally Posted by R Leo

I resemble that remark...

FWIW, the bolt on the left side had originally been installed with the head aft. I saw absolutely no reason to fight with the brake booster, brake lines, electrical lines and gawd knows what else trying to get the bolt in there and chose to reinstall it instead, with the head toward the front and use a spring-loaded grapple to locate the nut on the end of the bolt after I got it through all the holes.

Remember, the reason that the holes wouldn't line up was because the UCA was canted forward slightly by the thickness of the sway arm bushings.

That's the difference. With the bolt going in from the firewall side, you can see the tail end of the bolt.

Also, the sway arm bushings had no effect on the UCA at that point because the bolt for the swaybar was not tightened yet. The end of the swaybar was located in the UCA, loose........no tightening of the bushings until the UCA was fully bolted up.

You'd struggle with it mightily if the UCA took on the angle of the swaybar..........especially with the vehicle up in the air. I'm surprised a vice grip on the bolt head managed to twist it sufficiently

vitop · #14 06-07-2014, 09:07 PM

I actually just got done with this job and my bolt heads were in the rear with the nuts in the front. Getting the drivers side bolt in was a real pain because of all the aformentioned tubes, wires, erc in the area by the fusebox.

Not something I really enjoyed. Working in that area is just such a pain. You can't get your hand in there and that hole is half way down and you can only see it a little anyway.

Well, it's done. I just need to get the rest of the front end back together, put the weight back on it and tighten things up and then get it aligned.