Squeaky subframe bushing - PeachParts Mercedes-Benz Forum

JHZR2 · #1 05-13-2020, 05:14 PM

My 300CD sat in my garage for about six years. I started driving it a bit again, and started noticing at slow speeds, sometimes I was hearing a squeak coming from the left rear. Thought it might be the shock, but traced it to what I believe is the subframe bushing. I’ll need to do another test, but I think I can feel the vibration in the subframe “holder” (the metal item that bolts to the bushing and to the floor).

I had a look. This is the right side:

Here is the other side. Pics weren’t great.

The rubber all feels good, the ride is soft and compliant, Lifting the side doesn’t result in the subframe hanging or lowering. I took a video:

https://youtu.be/w3H9OwnPoQo

It is pinched, I guess due to a bad lift placement or something. But I’m not sure that would be an issue. If I put my hand on it when moving like in the video, I can feel the subframe moving a bit. The bracket is solid, but it’s bolted to the body in two places.

So any ideas? I’d hate to replace a bushing just to find it was something else. I am thinking of spraying it with silicone oil and seeing if it quiets things. But I’d guess the rubber separated from the metal.

Any other thoughts or recommendations? I don’t recall if it’s possible to press these in without dropping the entire driveline and subframe. Thanks!

Diseasel300 · #2 05-13-2020, 07:17 PM

Unless the rubber bumper on top of the subframe bushing has failed, I don't see how it's even possible for the subframe bushing to make noise. The through-bolt is what actually holds it to the car. That flimsy little frame is there more for locating and reinforcement. If it is actually rubbing on the car, try taking a screwdriver or pry-bar and reshaping it so it doesn't rub.

Not sure about the 123, but the 126 bushings can be pressed out and in without removing suspension components or dropping the subframe. If things aren't horribly rusted, replacing both is a 1-2 hour job

JHZR2 · #3 05-13-2020, 07:24 PM

Car is totally rust free. The spray you see there is waxoyl I had done when I brought it back to the east coast from SOCAL.

It would be great to be able to get it in with a press on the car!

Usaguy · #4 05-13-2020, 08:08 PM

Quote:

Originally Posted by JHZR2

Car is totally rust free. The spray you see there is waxoyl I had done when I brought it back to the east coast from SOCAL.

It would be great to be able to get it in with a press on the car!

Many times the waxoyl stuff can get hard and start to crack and will accelerate the rusting process. Oil spray like NHOU or krown fluid film that you apply every year or 2 is the best stuff.

When I changed the bushings on my 300SE (almost the same design) I removed them with a screwdriver and when installing I lubed everything up with SYNTHETIC GREASE (important because it doesn't react with rubber) and placed a wooden piece between the subframe and the body and with a floor jack I pressed the mount into the subframe. I had a wooden jig pushing on the mount so that I pressed on the outside edges of the mount and not the middle.

I also had to have a second floor jack just holding the subframe because when you remove the big bolt holding the mount the rear springs will want to push the subframe to the ground

JHZR2 · #5 05-13-2020, 08:20 PM

Quote:

Originally Posted by christuna

Many times the waxoyl stuff can get hard and start to crack and will accelerate the rusting process. Oil spray like NHOU or krown fluid film that you apply every year or 2 is the best stuff.

When I changed the bushings on my 300SE (almost the same design) I removed them with a screwdriver and when installing I lubed everything up with SYNTHETIC GREASE (important because it doesn't react with rubber) and placed a wooden piece between the subframe and the body and with a floor jack I pressed the mount into the subframe. I had a wooden jig pushing on the mount so that I pressed on the outside edges of the mount and not the middle.

I also had to have a second floor jack just holding the subframe because when you remove the big bolt holding the mount the rear springs will want to push the subframe to the ground

Thanks. Yes, aware of the waxoyl concerns. My cd is not a DD and doesn’t see much rain and no salt or snow. I do top it with a spray oil (equivalent to Krown) which is why I’m not concerned. Wanted a barrier between oil and the OE undercoating.

So it seems like it is feasible. An SE I think has jacking pads, right? What I can see as not great here is how to lift a w123 in a spot that’s clear and clean and doesn’t damage back there. I’ve heard lifting by the diff isn’t great.

But the most important reason to know if it’s possible on the car is because I’m not seeing OE or Lemfoerder bushings available. Just junk.

Makes sense that the springs would want to force the subframe down. I think a bottle jack or 6x6 block of wood to limit it would suffice. Maybe you can even leave the wheel on and just do it that way??? I can see how it could get tight working back there.

Diseasel300 · #6 05-13-2020, 08:43 PM

Not sure on W123, but on W126 the only options of subframe bushings are Meyle. $80 for a set vs >$300 for MB. For the ENORMOUS difference in price, I can change the Meyle's nearly 4 times, so that's the route I went. Having done it on 2 W126's so far, they seem to hold up fine.

On the 126, the easiest way to change the subframe bushings is to jack the car up and put it on jackstands. Drop the bushing retainer bolts and the center through bolt. Jack up the subframe and insert a 24mm socket on top of the subframe mount. Lower the jack and let the subframe push its own mount out. Lube the new bushings with some silicone spray and jack it up into the hole with the jack, use the old bushing as a pusher. Reassembly is the reverse of removal as they say.

JHZR2 · #7 05-13-2020, 10:19 PM

Yeah, if it’s like that on the w123, I’m ok with Meyle. If it was more involved I’d want to find some OE ones...

JHZR2 · #8 05-14-2020, 07:55 PM

Tool acquired:

Based upon this thread:

1985 300D W123 Subframe Bushings Meyle

Diesel911 · #9 05-14-2020, 10:26 PM

I don't know about the squeaking issue but one of mine fell apart after I unbolted it. It is clear that the inner rubber that was supposed to stay laminated to the metal is shrunk and or worn away.

Diesel911 · #10 05-14-2020, 10:31 PM

Quote:

Originally Posted by JHZR2

Tool acquired:

Based upon this thread:

1985 300D W123 Subframe Bushings Meyle

Mine was lower budget and I used what I had at home already. I used WD-40 sprayed on the out side of the bushing to help it go all the way in and seat properly.
If you remember member Army later changed to Stretch like to use wood for various tools.

Diesel911 · #11 05-14-2020, 10:36 PM

I finally remembered the old thread for changing the Trailing Arm Bushings was by Wiskeydan.

JHZR2 · #12 05-15-2020, 09:39 AM

Quote:

Originally Posted by Diesel911

Mine was lower budget and I used what I had at home already. I used WD-40 sprayed on the out side of the bushing to help it go all the way in and seat properly.
If you remember member Army later changed to Stretch like to use wood for various tools.

What got me was that they said the floor flange was a perfect fit to support this.

Wood works too!!

JHZR2 · #13 05-16-2020, 12:31 AM

This is one of the easiest jobs I’ve done on a suspension part. I spent more time gathering the parts than doing the job.

The things I used are two pry bars (18” and 36”)
Heavy ball peen hammer
Milwaukee stubby m12 impact
Short impact sockets, 17 and 24mm
1” open and box wrenches
Home made tool
Sil glyde aerosol
Honda Shin Etsu grease
Fluid film
2 paper towels
Trolley jack
Bottle jack

I lifted the car slightly by the diff, but not enough to get the wheels off the ground.

I used a stubby impact to quickly get the bucket bolt out from the mount.

My car was a SoCal car that now lives in the garage most of the time... So...

After removing the metal bracket via unbolting the two 17mm bolts, it’s time to get the rubbber. One will have to pry out the old one. It has a lot of rubber in there, so you need to work around. I started with a short pry bar, hammered it in, and jimmied it out a little, then got a bigger/longer pry bar to get more contact and wedge it out more.

A decent difference:

At this point, look around. I saw that the undercoating isn’t as thick at the point where the bracket bolts to the body. This is where fluid film is useful - apply some to a rag, and liberally apply To the body and the bracket mating surface.

I thought I had a tube of sil glyde, but I couldn’t find it. I have Honda shin etsu grease, which is a silicone grease for rubber parts. I applied the sil glyde aerosol to the subframe cup (cleaned well), and shin etsu to the bushing..

The tool is ready. I generally followed the instructions from here:

1985 300D W123 Subframe Bushings Meyle

Essentially, it’s a 2” iron floor flange (black iron is cheaper, but HD sells galvanized), then I used a 2”-1” bushing, and a 1”-3/4” bushing. 5/8” threaded rod was used, and nuts (need three). Plus the largest and thickest 5/8 and 3/4” washers they sell.

I also used moly paste on the threads and nut interface which helped immensely.

Ready to go...

And, in. Note the lubed threads.

One word of caution - be patient. Maybe it’s because I lubed it, but once I relieved tension, it came out a bit... maybe 1/3 of the way out.

So I tightened it back in and waited maybe 10 minutes. I also tapped the assembly and subframe, fwiw. On the second try it did not back out again...

So it is important to get alignment. I barely raised the car, and had the subframe somewhat supported by a bottle jack. I tried raising and lowering to get more space above the subframe, but perhaps since I left the tire on, it made it sit at strange angles I was not comfortable with. So I tried to minimize how I moved the vehicle, but worked the subframe a bit to ensure alignment.

Maybe that’s not necessary, but it sure seemed to me that it made it easier to get the bucket bolt threaded.

When done it’s obvious how much more the bushings raise the rear end.

You can see the height difference, maybe 8-9mm?

In the end it took far longer to think about doing the job, buying the tool parts, and lifting the car, than doing the job. This job truly is easy, which is why I wasn’t concerned about Meyle parts. It seems OE parts are NLA, but these are so easy to do in place, If they done last I’ll be ok with being ahead the money.. especially now that I have the tool.

Tomorrow I’ll drive it and see if that was truly the squeak, or if there are others!

JHZR2 · #14 05-16-2020, 11:38 PM

Did the other side, and the rear shocks, and it seems the squeak is gone, and the ride at highway speeds is significantly better. We just did 160 miles in the car and it was smooth and comfortable, really a great ride.

Same sort of height difference.

That said, the second one was a far worse job to do, and my concerns with Meyle were further confirmed. The second one was a bear to get in. It would go in all right. But it would immediately squeeze back out. I literally tried it ten times, different orientation, trying to leave it in place, compressed, part and fully for long periods of time. No luck. Nothing I did kept it in. And it was quick enough to squeeze out that by the time the press took was removed, it was nearly impossible to get the bolt in. I greased it, increased it, no luck.

Finally, using a lack on the press tool yielded just enough improvement to get the bolt threaded a few threads in... which was quite a feat. I couldn’t get the bushing in all the way in such a scenario.

This was the best I could do by the time I got the bullet bolt in place.

It was torqued to 120 nm. I figured it was worth the risk of damaging the mount since I will be complaining to Meyle fwiw. I really wanted to take the car on our pm road trip.

After 80 miles I checked it. The bushing has settled in somewhat. I’d say it went from a 1/4” gap to a 1/8” gap. Maybe some more driving and some hot-cold cycles will help. I’m hesitant to take the stiffening plate off, but I’d consider some other attempt to seat it in place if it doesn’t go all the way back out.

The seated look is much better.

But still a bit of a gap. The bolt torque was totally fine.

So I’m thinking this must be meyle QC. Granted someone on here also noted that ps was harder than ds too. Wonder why?

JHZR2 · #15 05-17-2020, 02:28 PM

After 160 miles I’d say it’s good enough for government work.

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