Improving ride quality and handling of a C350 CDI sport

[6cyl]

I've had numerous cars and driven many more, from track biased to luxo barges.

I find my C350 CDI saloon Sport quite harsh in terms of comfort, but without the handling benefits. I reckon the springs rates are too high and the dampers don't seem to react to road irregularities well enough. Too much stiction ? If it was my motorbike, I'd use softer springs, lower the compression and increase the rebound to slow down the up stroke.

To put some perspective on this, I rate the ride like so :

MB S350 (2011) Air suspension 18"
Alpina B3S (2011) 19"
BMW M3 (2003) Ohlins 19", polybushed
BMW 530i M Sport (2008) 19"
MB E250 CDI Sport (2013) 17" Conti SC5
VW Golf GTI ED30 (2007) 18"
BMW M3 (2005) AP Coilovers 18"
BMW 530D SE (2005) 17"
MB C350CDI (2010) 17" Conti SC5
BMW X3 (2007) M Sport 18"
Audi A4 S Line (2005-2009) 18"
Audi S3 (2002) 17"
VW Golf GTI (1990) 15" on slicks, Koni track biased suspension, rose jointed, camber plates


What do you guys think ?

I'm looking for is which combination of dampers and springs and geo setting work well and to elicit other people's experiences so that I don't have to get the car on a suspension test rig and go full bespoke.

 

[television]

If you are running at the stupidly high tyre pressures as indicated in the fuel flap, try running on 32psi front and 34psi rears

 

[6cyl]

Malcolm,
got the tyres pumped up at 2.5bar that's a tad above 36psi I believe, as indicated in the fuel flap ....

 

[6cyl]

Also don't think the tyre pressure has much bearing on the primary ride quality, more on the NVH and harshness, as the tyres don't provide much of the damping in our cars. I think MB has economised on the quality of the dampers, used springs which are too hard and not enough rebound on the damper.

 

[EmilysDad]

....

I find my C350 CDI saloon Sport quite harsh in terms of comfort, ....

do you get a comfy sports car? are the two words themselves not a conflict of interest?

 

[6cyl]

Yes you can get a car that is comfortable and handles well. The two words are not conflicting at all. Thats why I ranked my C350 in a list with other cars. Notice they have 19" wheels. The 530 was on Maragoni (!!!) tyres from the franchised dealer, even that was significantly better.

Alpina B3S (2011) 19"
BMW M3 (2003) Ohlins 19", polybushed
BMW 530i M Sport (2008) 19"

All handle significantly better than my C350, yet are significantly more comfortable, especially the Alpina. It has "plush" suspension and well damped and sprung suspension. The C350 feels more like an Audi A4/A5/A6 Sportline. Hard and over damped on the compression and underdamped on the rebound.

 

[gizze]

My E350cdi was exactly the same, really didn't handle the poor UK surfaces well at all, it skipped about on anything but billiard table flat roads and felt more like my early 535d on run flats in that regard.

I would however agree with Malcolm and try and drop the pressures a bit, 36psi is great for economy but does loose out on comfort and some grip on poorer surfaces, I ended up at 32F and 34R and it felt much better, but still never that happy with the results.
Unfortunately I had been in an F11 5 series touring just before the E350cdi which handled far better and was much comfier as well, even in runflats.

I do think that you're right, it needs a more progressive spring and better strut that has better rebound, as they just seem to get caught out.

But do try dropping the pressures a bit, it does help comfort and gives more bite on poorer surfaces.

 

[Scoob]

While my C350 CDI Sport Estate has quite a firm ride, I love it. It also feels exceedingly well planted, one of the best cars I've driven in this regard.

Now, it usually runs on 18's with appropriate rubber. However, while my wheels were being refurbished it was running on 16" wheels, but with tyres that gave the same overall diameter - or rolling radius to be precise. This extra bit of squishiness gave the car a superbly smooth ride, even on fairly rough roads. The compromise was of course additional tyre roll during even fairly mild cornering, so the car felt much less planted, but still ok.

Basically, I was surprised how much difference just running smaller wheels with higher (aspect ratio) rubber made to the ride. I do prefer the car to be slightly firmer though if I'm honest, so I'll be keeping the 18's on it, but am looking at 16's for my winter tyres hopefully.

Oh, I get that lowering tyre pressures can help certain aspects of the ride, namely driving straight. However, lower pressures do seem to compromise both wear (the edge wears more quickly) plus cornering suffers from tyre roll. I'm not talking extreme cornering by any means, it's just that these cars are heavy so the effect is exaggerated by this.

Note: I do run "XL" tyres which, as discussed in another thread, seem to like a little extra pressure. So, with XL's fitted the fuel cap "Up to three people" figure seems to work quite well - caveat: for me & to my personal taste.

One final thing. When I got the car it was still on the OEM Conti's - they had about 4mm left on them. After a pot hole incident popped one and damaged another I got them all replaced with Dunlop Sport Maxx GT XL's. Maybe it was just that the old tyres were part worn, but the new tyres improved the ride no end. I was surprised.

Scoob.