About to tackle guide rod bushings on '81 300SD - Page 2 - PeachParts Mercedes-Benz Forum

Alec300SD · #16 01-31-2016, 04:18 PM

Quote:

Originally Posted by sixto

I don't believe this to be an alternative because the OE bolt is too long to move clear of the guide rod with lower spring perch in place. I thought about cutting a hole in the spring perch to allow the bolt to go through but either or both the highly remote chance I'd do this job again on the same car and possibly the bolt is directly under the spring dissuaded me. But why is this alternative unsafe? If you unbolt the guide rod mount carrier (110) from the frame, the spring doesn't push the LCA away and break free. It takes tremendous force to move the LCA forward with a jack or come-along as it is.

Sixto
83 300SD

I wrote Option B late at night without actually looking at the physical parts on my car. I should have looked before I wrote.

Sixto, you are right it should be safe to remove the nut (# 107) and bolt (# 89). The spring can't pop out of the perch as the LCA (# 77) is held in place by the shock, steering knuckle and eccentric bolt in the inner end on the LCA.

I haven't done that method (Option B) but it should work. I envision it proceeding like so:

Option B
1) Front wheel off, side raised, car supported by jack stand, tire under side of car (just in case jack stand fails), wheels chocked, eye protection on. Remove six bolts (# 138) attaching the brace to the bearing brackets (# 110).

2) Remove two bolts (# 134) that attach the bearing bracket to the body.

3) Remove or loosen the clamp bolt in the threaded end of the guide rod (# 92). Count and record the number of visible threads on the shaft of the ball joint (# 120) between the hexagonal wrench hold on the shaft and the caster adjusting nut (# 131). This gives you the rough caster adjustment for the new ball joint you will install later.

4) Turn the caster adjusting nut (# 131) clockwise until it bottoms out against the wrench hold on the ball joint shaft.

5) Remove the nut (# 107). To avoid damaging the threads of the bolt (# 89), use a small drift to push or hammer the bolt (# 89) up and out of the spring perch (# 86). The flat end of the guide rod (# 92) may come out of the pocket formed by the 2 metal cups and 2 rubber grommet still under the spring perch. If not go onto step six.

6) Move the LCA forward by just pushing on it, pulling it with a come along winch , or by pushing on it with a OEM "widow maker" jack wedged horizontally into the wheel well (as previously described in post # 4 of this thread). This should free the guide rod (# 92) and the attached bearing bracket (# 110) from the LCA.

OldStar, if you elect to use the Option B above, take photos
and post them if you can.

Thanks Sixto for your help in making me rethink Option B.

sixto · #17 01-31-2016, 04:22 PM

Spinning the carrier will make quick work of it but anything you do to not have to move the LCA or deal with rusted perch bolts seems like a win to me.

Sixto
83 300SD

Alec300SD · #18 01-31-2016, 05:23 PM

Quote:

Originally Posted by sixto

Spinning the carrier will make quick work of it but anything you do to not have to move the LCA or deal with rusted perch bolts seems like a win to me.

Sixto
83 300SD

Of course I haven't tried Option B yet, nor will I for the forseeable future.

Just to be clear, are you meaning that after step 4, the bearing bracket (# 110) will be able to drop down low enough that there is enough room so you can spin the whole bearing bracket (# 110) without interference from the body?

If that is so, then there is no need to do step 5 or step 6 and that would be sweet.

SD Blue · #19 02-01-2016, 04:33 PM

Don't over-analyze this. I've changed out the guide rod bearing mounts and the bushings in the bearing mounts, as well. There is no need for a spring compressor if you do a couple of things.

The spring needs to have a load, so I used ramps. I know some have sworn off the use of ramps but I'm not skinny enough to get under there far enough to work. Just be safe and don't take short-cuts.

As you mentioned, removing the "dog bone" bearing mount bolts. Mark the threads then you unscrew the guide rod bushing from the end of the guide rod.

Where a come-along comes into play is when you try to install the bolts for the bearing mount after the repair. I hooked one end to the LCA and the other towards the rear (I believe I used a large punch in the jack point for an anchor.

I haven't tried this but you might even be able to just use longer bolts, replacing them one-at-a-time, for the bearing mount. This may be just enough to pry the bearing mount down and replace the bushing. I doesn't take much to get enough clearance to unscrew the bolts holding the cover on the back side of the bushing. This might work if you don't have ramps or a come-along and need to support the wheel with an alternative.

vstech · #20 02-01-2016, 09:03 PM

It's simple. Just take it apart, push the dog bone onto the shift then unscrew the bushing.

Putting it back together, is the reverse, use long bolts to reinsert the bushing into the dogbone.

First time I did it, I put bushing into dogbone and couldn't spin in place, had to take it all back apart. Goes smoothly if you use the right sequence.