Rear subframe bushing upgrade?
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Senior Member
Joined: Mar 2023
Posts: 281
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C230K
Rear subframe bushing upgrade?
Hello all, have any of you upgraded your rear subframe bushings with polyurethane or solid bushes? I know my car’s bushings are original, so I plan to address them.
I am considering an upgrade to poly or solid, because I’m looking for precise feedback from the rear end, especially during throttle application. If this upgrade results in additional wear and tear on the car, then I’d rather not proceed with it. I don’t want to rip out my subframe mounts or anything like that.
My suspension is likely going to remain OEM. I may consider stiffer springs, say about 20-30% stiffer, but coilovers will not be considered. My suspension arms are also going to be OEM and bushed with rubber.
I also have some concerns about NVH. I can tolerate a bit of NVH, but I would very pretty disappointed if I had to listen to my differential whine during a drive.
Thank you. Please let me know if you have any questions, and I will do my best to clarify for you.
I am considering an upgrade to poly or solid, because I’m looking for precise feedback from the rear end, especially during throttle application. If this upgrade results in additional wear and tear on the car, then I’d rather not proceed with it. I don’t want to rip out my subframe mounts or anything like that.
My suspension is likely going to remain OEM. I may consider stiffer springs, say about 20-30% stiffer, but coilovers will not be considered. My suspension arms are also going to be OEM and bushed with rubber.
I also have some concerns about NVH. I can tolerate a bit of NVH, but I would very pretty disappointed if I had to listen to my differential whine during a drive.
Thank you. Please let me know if you have any questions, and I will do my best to clarify for you.
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Joined: Mar 2016
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From: SF Bay Area, CA
190E 2.6L 1989, 190E 2.6L 1988, BMW 535dXdrive 2014, BMW 428i 2015
Owning a couple of cars and restored my original and still restoring the second one I can safely say that Mercedes has already engineered the sportline suspension to optimize ride quality and performance.
One of mine is converted sportline with all Mercedes parts and the other is 124 springs with coils cut a turn. The shocks are all Billstein B8's.
So effectively what you are looking for. This (124 springs) is what people do on a budget.
I can safely say that suspension design is definitely a lot of engineering and trial and error. Be ready for plenty of disappointments if you do not follow a tried an true set-up.
My recommendation is the Mercedes Sportline. It is vastly better than the original set-up and no experimentation.
Similarly, all the bushings are also all engineered and experimented with. Yes it is 40 year old technology but the subframe bushings lasted 35 years or more. All my subframe bushings are original.
If I ever changed them I would use the original rubber style.
Mercedes designed the suspension with a lot of rubber bits and if any go bad the drive quality really suffers, and one starts hearing knocking and thumping sounds, especially with manual transmissions.
So I would be cautious about changing those to poly or some other material that is less rubbery. Definitely seek advice from owners who have done that swap. I myself would never try it based on what I have seen in the past 36 years.
One of mine is converted sportline with all Mercedes parts and the other is 124 springs with coils cut a turn. The shocks are all Billstein B8's.
So effectively what you are looking for. This (124 springs) is what people do on a budget.
I can safely say that suspension design is definitely a lot of engineering and trial and error. Be ready for plenty of disappointments if you do not follow a tried an true set-up.
My recommendation is the Mercedes Sportline. It is vastly better than the original set-up and no experimentation.
Similarly, all the bushings are also all engineered and experimented with. Yes it is 40 year old technology but the subframe bushings lasted 35 years or more. All my subframe bushings are original.
If I ever changed them I would use the original rubber style.
Mercedes designed the suspension with a lot of rubber bits and if any go bad the drive quality really suffers, and one starts hearing knocking and thumping sounds, especially with manual transmissions.
So I would be cautious about changing those to poly or some other material that is less rubbery. Definitely seek advice from owners who have done that swap. I myself would never try it based on what I have seen in the past 36 years.
Thread Starter
Senior Member
Joined: Mar 2023
Posts: 281
Likes: 88
C230K
How long ago did you perform the Sportline conversion? I assume it would be really difficult to get the parts nowadays, unless you think it’s something that MB Classic can supply?
Do the Sportline and 16v cars use a different subframe bushing than the base model cars? Like a sportier, slightly stiffer durometer rubber bushing?
Yeah, I understand the trial and error bit, and I’m too worn out to want to try that again. I’m probably going to also stick to rubber unless I’m convinced the poly or solid is exactly what I’m looking for.
Do the Sportline and 16v cars use a different subframe bushing than the base model cars? Like a sportier, slightly stiffer durometer rubber bushing?
Yeah, I understand the trial and error bit, and I’m too worn out to want to try that again. I’m probably going to also stick to rubber unless I’m convinced the poly or solid is exactly what I’m looking for.
MBWorld Fanatic!
Joined: Mar 2016
Posts: 1,369
Likes: 195
From: SF Bay Area, CA
190E 2.6L 1989, 190E 2.6L 1988, BMW 535dXdrive 2014, BMW 428i 2015
How long ago did you perform the Sportline conversion? I assume it would be really difficult to get the parts nowadays, unless you think it’s something that MB Classic can supply?
- I did my springs around 2018. Later in 2020 I purchased an new sportline front roll bar and around 2021 I purchased the rear roll bar from the dealership. So done over time. I know they had plenty of sporline springs in germany around 2018. It was like 100 each of front and rear. That is probably depleted by now. Check with your dealership and MBclassis. At the dealership you will need part numbers or a sportline VIN.
Do the Sportline and 16v cars use a different subframe bushing than the base model cars? Like a sportier, slightly stiffer durometer rubber bushing?
- I doubt it. If anything they will be softer, not harder. Because the rear roll bar is weaker on a sportline than the standard. See what I mean by it is sometimes counter intuitive when it comes to suspension. Sportline is optimized for less roll up front, and when that is done, if you do not soften the rear a bit the car may drive like a track car not a street car. But check to see if they are different when it comes to bushings. BTW, as far as I know they are NLA at the dealership, you will need to go aftermarket or try MBClassic center.
Yeah, I understand the trial and error bit, and I’m too worn out to want to try that again. I’m probably going to also stick to rubber unless I’m convinced the poly or solid is exactly what I’m looking for.
- I would stick with rubber and I saw a tool to make this easier. Search and find that tool. It is an extractor of sorts. Otherwise it will be difficult. Let us know how it turnsout.
- I did my springs around 2018. Later in 2020 I purchased an new sportline front roll bar and around 2021 I purchased the rear roll bar from the dealership. So done over time. I know they had plenty of sporline springs in germany around 2018. It was like 100 each of front and rear. That is probably depleted by now. Check with your dealership and MBclassis. At the dealership you will need part numbers or a sportline VIN.
Do the Sportline and 16v cars use a different subframe bushing than the base model cars? Like a sportier, slightly stiffer durometer rubber bushing?
- I doubt it. If anything they will be softer, not harder. Because the rear roll bar is weaker on a sportline than the standard. See what I mean by it is sometimes counter intuitive when it comes to suspension. Sportline is optimized for less roll up front, and when that is done, if you do not soften the rear a bit the car may drive like a track car not a street car. But check to see if they are different when it comes to bushings. BTW, as far as I know they are NLA at the dealership, you will need to go aftermarket or try MBClassic center.
Yeah, I understand the trial and error bit, and I’m too worn out to want to try that again. I’m probably going to also stick to rubber unless I’m convinced the poly or solid is exactly what I’m looking for.
- I would stick with rubber and I saw a tool to make this easier. Search and find that tool. It is an extractor of sorts. Otherwise it will be difficult. Let us know how it turnsout.
MBWorld Fanatic!
Joined: Feb 2020
Posts: 1,995
Likes: 394
1991 190E 2.3
My robber suspension bushings lasted 30 years and I replaced them with rubber bushings. I think lasting 30 years is petty good durability. I 'm not sure why you want to stiffen the ride of your car. That somewhat defeats the purpose of having a comfortable riding car imho. Just my 2 cents.
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