geminimadman

Trying to get some advice on where to go next.

2013 C300 4matic sport w/ 80K miles.
Mods: Full window tint, AMR performance ECU tune, resonator delete, B6 shocks, H&R sport springs.

History: Car started driving fairly rough earlier this year. Could feel every bump in the road, body roll was pretty significant, would dip when braking, bouncing around on pot holes, etc. I decided to start with shocks and springs. That fixed some issues but not all and not sure where to go next.

A friend of mine is a mechanic and specializes in MB so he does most of the heavy work and I had him do the suspension.

I bought new Bilstein B6's and H&R sport springs along with OEM upper and lower spring seats and aftermarket strut mounts. After that work was done there was significant improvement in the body roll, dipping when breaking and overall "loose" feeling when driving the car but I still feel almost every bump and the car definitely feels like it wants to jump around when going over pot holes. I know its supposed to ride firmer with the B6's & H&R setup but Im wondering if there's some other failing components. I had my mechanic look over the motor mounts, transmission mounts, control arm and sway bar bushings when he did the shocks and springs and he said they all seemed and looked fine however I know from experience (particularly motor mounts) they can look fine when inspecting but can still be worn and/or failing.

My question is where to go from here. I am trying to decide If I should do all the mounts next or go with new lower/upper control arm and sway bar bushings. I can't afford to do both right now so looking for some advice on the next likely suspect. Im somewhat mechanically inclined any may be able to do the bushings myself (I haven't researched it enough yet) but I know I don't want to do the motor mounts myself.

Any suggestions and/or diagnostic tests I can do would be greatly appreciated!

On a side note the B6 & HR sport spring setup pretty much kept me at the same ride height as the OEM sport which is what I was going for. Would've gone with B8's but they are not available for the C300 4matic USA version.

EDIT: Forgot to mention I did have my wife help with motor mount test and when in drive, the drive side of the motor does raise up a bit compared to the passenger side when in reverse. Its not huge..maybe around 1" or so. The diver side definitely raised more then the passenger side though. Maybe that's a sign of it starting to go? Should it not raise up at all?

Glock_19_9mm

I would jack the front wheels up and test for tie rod looseness (try to wiggle 3 to 9 position) and wheel bearing wear ( try to wiggle 12 to 6 position). You should not be able to wiggle the tire at all. If you can you have an issue.

I just redid my suspension at 90k. While the stuff looked ok, it was definitely worn and I had to remove most of it to do the struts so it wasn’t much more effort to swap everything out, just more for the parts.

On another vehicle in my stable that seemed squirrelly like you describe, the inner tie rods were worn out. Swapped those out and the car rides fine now.

Hopefully the wiggle test will point you in a direction.

geminimadman

Thanks for the reply and suggestions!

I'll start with that this weekend and see if there's any play. Seems like any car with 80-100k miles will have some pretty good wear and tear on the suspension as well as mounts and bushings. I was looking at this kit (see below) and it includes inner and outer tie rods. Wasn't sure about the brand and if there's brands I should stay away from. Do you have any recommendations for brand (for suspension components and mounts)?

https://www.rockauto.com/en/moreinfo...=15413&jsn=967

Also, what would you say is the level of difficulty for doing this on your own? I do some stuff like oil changes and brakes and have changed struts in the past but I'm older now and have back issues which makes it harder. I don't like working on stuff that's under load and needs to be compressed. Other than specialty sockets do you need any other special tools or is it fairly straight forward?

Glock_19_9mm

I went with Lemforder for the suspension parts. Others may have other thoughts, but they appear to be OEM quality. And if you get them from FCP the have a lifetime warranty so you are covered (about $141 for inner and outer). Somehow it just seemed wrong to put an AC Delco on a Benz... (not that there is anything wrong with AC Delco).

Swapping out the tie rods was pretty straight forward. I would recommend a ball joint separator, not required but makes it easier with lack of space to get a BFH in there (mine were really on there).. Otherwise standard stuff (Metric sockets and hex keys). You will need an alignment after you swap them out so make sure to plan for that.

While you are under there I would look at the cross strut (essentially lower control arm) and see if it is leaking.. It comes from the hub and goes towards the front of the vehicle. If it is leaking oil you will see it at the subframe mount. I had one leaking and the other was not far behind... It is all in the same area so while you are there might as well knock it all out..