Subframe bushing fun - PeachParts Mercedes-Benz Forum

JohnM. · #1 04-02-2011, 01:09 AM

Finally getting around to replacing my front rear subframe bushings. My passenger wheel in particular has been "steering" the car all over the road the last month or two. Feels very unsafe at speed especially with just a light crosswind. I think a 40 minute snow drifting session is what finally did the mount in a few months back. Very next time I went out to play around..was getting very weird vibrations/flexing feeling from the passenger rear wheel.

Well this was why. The core of the bushing had "turned" inside, so the subframe mount was basically doing nothing on that wheel! Whenever it turned/broke...it also ripped off the rubber plated washer! It was nowhere to be found except for .25" of remnants around the bolt. I was able to pop this one out surprisingly well without tearing the core out, so the other side should be no problem.

Stretch · #2 04-02-2011, 03:14 PM

Wow that's an impressive twist.

Check your camber when you're done just to be sure everything is back where it should be.

lee polowczuk · #3 04-02-2011, 04:56 PM

looks like rust came into play here.

congrats.

JohnM. · #4 04-02-2011, 06:56 PM

Quote:

Originally Posted by lee polowczuk

looks like rust came into play here.

congrats.

I think the rubber core failure was unrelated to rust. But I am having a hell of a time getting the new bushing to seat even halfway. It's frozen solid too.

After taking a closer look at the subframe pocket there is def a small amount of rust in there. Do I need to clean this up with a dremel to get the new bushing to seat? All of the sides except the flat side are perfectly smooth, the flat side has "rust ridges" where the rubber bushing used to sit. I assume this is holding up the new one.

JohnM. · #5 04-02-2011, 09:14 PM

Anyone have a picture of what the subframe pocket is supposed to look like?

JohnM. · #6 04-02-2011, 10:22 PM

I cleaned out the pocket lightly with a dremel, and that actually got the bushing to seat 3/4 of the way but not enough. I've probably removed a few thousands worth of surface rust from the back wall and I know I've gone far enough when I hit the black subframe coating. I'm doing the finish smoothing with sandpaper so I don't go too far. What a PAIN. Gonna try the other frozen mount and hope I get lucky. The other side shoudn't have this problem. I wish I would have started with that side so I know what the pocket is SUPPOSED to look like.

Figured out the rust in the pocket is due to the large rubber backed washer that was missing from the bottom of the mount...allowing water/snow/grit whatever in there.

lee polowczuk · #7 04-02-2011, 10:38 PM

did you put the bushings in your freezer to shrink them a bit?

mak · #8 04-02-2011, 10:55 PM

Rubber grease is most helpful in bushing fitments .

JohnM. · #9 04-02-2011, 11:15 PM

Both bushings have been in the freezer for a few days. But the first one thawed out while I was dealing with the pocket issues. I'm using silicon based lube.

Good news though. Spent another hour cleaning rust out of the pocket and sanded it smooth. Thankfully the pocket isn't RUSTED through (all I need right now is a new subframe project

), but it was on its way for sure. Just thick areas of surface cancer in there where the rubber bushing had degraded. Pocket went back to the factory black finish though, even after somewhat heavy Dremeling/sanding. Gotta love Benz quality.

Took the second bushing out of the freezer and it seated 3/4 of the way almost immediately. A little "working" and few dead blow hammer hits to the subframe and it seated with less than 1/8" to go. I will leave it jacked up for an hour or so and it should go down the rest of the way. Thank god.

JohnM. · #10 04-03-2011, 12:24 AM

Fully seated! Was worried that if I didn't clear enough of the bottom pocket, it would seat most of the way, and I'd tear it up popping it back out. I figure the driver side should take me an 1-1.5hr tops since there will be no rust issues.

I can't wait for the test drive! My car used to handle like a million dollars...but this subframe bushing issue made it worse than your average beater as far as how it feels to be sitting in the drivers seat. High speed cruising went to *****!

lee polowczuk · #11 04-03-2011, 08:40 AM

Quote:

Originally Posted by JohnM.

Fully seated! Was worried that if I didn't clear enough of the bottom pocket, it would seat most of the way, and I'd tear it up popping it back out. I figure the driver side should take me an 1-1.5hr tops since there will be no rust issues.

I can't wait for the test drive! My car used to handle like a million dollars...but this subframe bushing issue made it worse than your average beater as far as how it feels to be sitting in the drivers seat. High speed cruising went to *****!

i think you are going to have a nice ride...... few have done subframe bushings.

you will have to tell us about the ride when you get done.

JohnM. · #12 04-03-2011, 07:13 PM

Quote:

Originally Posted by JohnM.

I figure the driver side should take me an 1-1.5hr tops since there will be no rust issues.]

I hate it when I jinx myself.

4 HOURS to just remove the driver side subframe mount. This one was actually in WORSE shape than the other side although it failed in a completely different way. Right after I unbolted the mount, the core fell out without any help! Oddly enough, this wheel felt more solid than the other one while driving.

No core left me nothing to push the bushing out with. I was able to pry the bushing out .50" or so, giving me enough room to slide a piece of steel scrap (took a few tries to get the size right) in the bottom of the pocket and then use a socket to pop the mount out.

Looks like I have a lot of rust clean-up in this subframe pocket too.

Passenger bushing on left, new in middle, driver on right. THINK THERE WILL BE A DIFFERENCE!?

d.delano · #13 04-03-2011, 11:00 PM

Ugh I have to do the same. Your car theoretically should be transformed. It is a rarity that the subframe gets addressed, as most seem to think the mounts & bushings last forever. They Don't!

What was your jacking up strategy with this? I'd like to do both front and rear sub mounts, plus the diff mounts & multilinks. Doesn't seem worth it to even bother to take the wheel off if you're not going to blitzkrieg it and do it all at once, considering the car's age. Often replacing a couple easy-to-get-to items here and there just amplifies other problems. If you want it to drive like a new car there's only one approach to take. Blitzkrieg!

Also, you didn't mention whether you had any of those expensive special bushing tools. Is the job possible without?

JohnM. · #14 04-03-2011, 11:12 PM

All wrapped up and back from the test drive. It truly is like a new car! It doesn't wander between lanes by itself anymore, the rear follows the front through corners, fine steering adjustment is finally back! Plus it is so much quieter in the cabin. The rear was very "clunky" beforehand, it reminded me of my old VW Bug. Now its dead quiet over bumps/dips (I can feel the new rubber cushioning

)...all the weird rattles/squeaks from the back seat area are gone as well. That's like half a dozen things fixed.

Took it out on the highway up to 80-85mph...perfect. Plus there was nearly a 40mph crosswind! Barely affected me. When before a 5mph cross wind was blowing me all over. Testing conditions couldn't have been better!

IMO, the front mounts take all of the torque/wear. I inspected the rear subframe mounts on mine and they were OK. I will do a short write up on R&R the front mounts. The diff mounts WILL require a special tool or you risk damaging the soft metal in the subframe, you can find people selling it on eBay. Otherwise this job required more ingenuity and creativity than any special tools. I'd say the arms, diff mounts, subframe mounts are all separate projects unless you are a glutton for punishment.

slk230red · #15 04-04-2011, 10:56 AM

Great thread John.

I had to replace the front rear sub-frame mounts several years ago on my '93 190e that I purchased new. There were no rust issues, just torn deteriorated rubber on the passenger side rear front bushing.
My wife drove home from work and said the car drove funny. I had her take off in front of me while I watched....I could see a lot of movement in the right rear wheel. I jacked up the right rear and used a 2x4 to pry up on the wheel and could see play in the bushing. The next day I replaced and bushings and problem solved.

It's hard to get people to check the sub-frame bushings when they complain about drifting, vibrations, clunks, etc.