Instability - is it normal(ish)

[television]

As Nick (Bolide) say's forget the shock obsorbers, it has to be one, or more of the list he put up.

Malcolm

 

[jonnyb1]

EXcuse me. there is a 70mph max speed limit in GB.....these 80/90s figures seem to show that people are acting silly,(and please,no .....its a merc hence safe at these speeds)

 

[angus falconer]

EXcuse me. there is a 70mph max speed limit in GB.....these 80/90s figures seem to show that people are acting silly,(and please,no .....its a merc hence safe at these speeds)

I don't see many people doing 70mph day to day on the M40 near me. And those that do cause the traffic to bunch up dangerously.

I say, relax and go with the flow - 85-90 seems normal.

As a cop once said to me (when booking me) "stay below 90 and we won't touch you"

 

[jberks]

EXcuse me. there is a 70mph max speed limit in GB.....these 80/90s figures seem to show that people are acting silly,(and please,no .....its a merc hence safe at these speeds)

Anyone tried doing 70? Pretty much impossible. Its either 50-60 with the trucks or 80-100 with everyone else. And yes, a Merc well maintained is perfectly safe at those speeds!


Don't get me started on a late 60's car being far more dangerous at 70 than a modern one is at 120!! My Diesel will outrun and out stop most supercars from that era ..........
The problem with modern limits is that they are applied bindly by people who have never actually driven a car aside from the 2cv they had as a student and only ever ride push bikes around London. Fog and heavy rain at rush hour on the M4, 70 is way too fast (and pointless too). M6 near the lakes, 8pm on a summer Sunday evening, 120 would be fine! Bring in variable limits and maybe we'll respect them!

 

[Blobcat]

Speed is not dangerous, it is inappropriate speed which is.
It is the conditions that dictate what speed is safe not some outdated law and a camera sat on the side of the road.
Last year in Germany I drove at 145mph as the road was clear the conditions were fine and the car was built for those speeds. On the Way back I was doing around 40mph on the same stretch of road as it was raining hard and there was lots of traffic around. Driving 40mph on the way back was more dangerous than 145 on the way out
Although people can argue that any speed is dangerous so lets all leave the cars parked up and walk everywhere.

 

[Rory]

Hi All
Having read the thread about the wondering problem on motorways, over 70mph, my car have the same symptoms. I dare not drive over 90 as it does not feel safe!
Regards
Majid

C200, W reg, 2000, 85K miles

I have a late 2004 (so latest facelift) C270 Estate, that I got when it was 6mths old, with 6000 miles.
It's my first Merc and the one disappointing thing about it is how unstable - more a sort of nervousness really - it feels on the motorway. Nothing severe, it just never really feels 'planted'.

After many years of FWD cars I wondered if maybe all RWD cars are like this, but I recently went for a drive in a friends previous shape 5 Series BMW and that was a revelation. I wonder if E Class feels the same.

 

[Blobcat]

I have a late 2004 (so latest facelift) C270 Estate, that I got when it was 6mths old, with 6000 miles.
It's my first Merc and the one disappointing thing about it is how unstable - more a sort of nervousness really - it feels on the motorway. Nothing severe, it just never really feels 'planted'.

After many years of FWD cars I wondered if maybe all RWD cars are like this, but I recently went for a drive in a friends previous shape 5 Series BMW and that was a revelation. I wonder if E Class feels the same.

I have a W210 E320CDI and it is stable as a rock. As per my posting above in this thread I have had a GPS confirmed 145mpph out of it. Mine has the parameter steering. I drove a collegues E220CDI with the normal steering and his felt vague at speed. His was also on Dunlops which were noisy as hell and did not instill confidence.

 

[television]

I do not feel that FWD or RWD has anything in itself to do with stability on any road or speed. I have taken the V70R up to 145 and the SL up to 125 on motorways and both feel fine and hold a good straight course. On lesser roads I cant throw either of them around owing to the weight though they both stick to the road like glue and I have no intention to find the point where they leave the road.

Malcolm

 

[turnipsock]

I thought 70mph was an advisory speed limit.

 

[Rory]

I have a W210 E320CDI and it is stable as a rock. As per my posting above in this thread I have had a GPS confirmed 145mpph out of it. Mine has the parameter steering. I drove a collegues E220CDI with the normal steering and his felt vague at speed. His was also on Dunlops which were noisy as hell and did not instill confidence.

Yes, 'vague' would be a good description. If anything I'd say it's better at higher speed - I've run reasonable distances at 125. Many cars have a speed that they'll settle nicely at, and unfortunately it isn't usually 70MPH.

What tyres are you on?
My car is on Bridgestone's which I feel are far too stiff in the sidewall - they're only 55 profile front and 50 back, so not terribly low profile these days, yet they feel like they're made of iron, even with the pressures on the low side. I've settled on replacing them with Michelin's, which as it happens, are the tyres my friends BMW has.

 

[Blobcat]

What tyres are you on?
My car is on Bridgestone's which I feel are far too stiff in the sidewall - they're only 55 profile front and 50 back, so not terribly low profile these days, yet they feel like they're made of iron, even with the pressures on the low side. I've settled on replacing them with Michelin's, which as it happens, are the tyres my friends BMW has.

Conti's - ecocontact 16" 55 profile

 

[malcolm E53 AMG]

In my opinon what most people on this thread are experiencing is air pressure under the car providing some lift. This varies with different speeds and cross winds etc. Avantgarde spec cars are less prone to this because of the lower ride height.

There is a fix of course but fitting a lip spolier to most Mercs would spoil the appearance. If its particularly bad on some cars I would consider spending the money on having the car lowered slightly.

 

[Blobcat]

In my opinon what most people on this thread are experiencing is air pressure under the car providing some lift. This varies with different speeds and cross winds etc. Avantgarde spec cars are less prone to this because of the lower ride height.

There is a fix of course but fitting a lip spolier to most Mercs would spoil the appearance. If its particularly bad on some cars I would consider spending the money on having the car lowered slightly.

Didn't MB have a problem of high speed lift at LeMans a couple of years back...

 

[philharve]

Hi All

After reading other threads concerning steering dampers I'm beginning to think this inexpensive, simple to replace item may be responsible for many of the speed-related instability problems mentioned in this thread.

I've changed the make of tyre and the tread pattern and the Merc' grips the road better than ever and is quieter. This simple modification has improved handling significantly. I'm betting that once a new steering damper is fitted it will transform the handling and cure the instability problem which suddenly appears as 3-figure speeds are approached. I hasten to add that I don't normally travel at these speeds. It's just that in a 140+ mph car, I'd like to think it had the stability to attain these speeds without putting the fear of God into the driver.

REGARDS Phil

 

[television]

Hello Phil, have a look at your car here under steering and you can see how simple it is.

http://www.detali.ru/cat/oem_mb0.asp?TP=1

Best regards, Malcolm

 

[philharve]

Hi Malcolm

I would not have thought of looking for information concerning Mercedes on a Russian website!!! I expected to find Cyrillic text but not English text too.

I found the 'steering diagram' you pointed me in the direction of without any trouble. The diagram of the steering linkages is very good, better than in my Haynes manual, in fact!

The information and its layout reminded me of the Mercedes parts catalogue which I purchased on CD some time ago on eBay.

I learned something else whilst browsing this Russian database. I went in search of the Kompressor (not to be confused with any other compressor on the vehicle) and found it located in the intake manifold section. I always assumed it merited a section of its own. However, it is not given any special mention in this database. Anyway, what surprised me was to find the kompressor referred to as a 'turbocharger'. This is not the common definition as used in the West but then Russian is a curious language.

I once tried to explain how transatlantic submarine telephone cables were laid to a party of Russian visitors but unexpectedly encountered some difficulty because 'submarine' only exists as a noun in the Russian language. They thought we used submarines to lay cables. Furthermore, submarines are regarded as vessels of war in Russia. I hastily tried to explain that 'submarine' is often used to explain something found beneath the surface of the waves. An awkward moment ... it could have lead to WW3!

So when searching unsuccessfully for 'kompressor' through a similar database, try 'turbocharger' instead. You might get lucky. When I'm next browsing my CD, I'll try using 'turbocharger' intead.

REGARDS Phil

 

[philharve]

Hi All

I've had a new steering damper fitted - the original was totally knackered - and a new pair of lower ball joints fitted. The indie only fits them in pairs, a MB requirement.

I took the car to a quiet stretch of the A30 and conducted some speed tests to see if the new damper and joints improved the instability issue. The car is much less twitchy at speeds around a hundred but I sensed the edginess/vagueness was still present but further up the speed range.

I asked the indie how his C180 performed at speed and he reported the twitchiness is a feature of all C-class models. Even the E-class suffers but to a lesser extent. The S-class is rock steady: it has a different steering geometry and is much heavier.

I inquired if this was a design fault? He said 'No'. He added that customers who complain can have their steering geometry adjusted (a recognized MB service) to almost eliminate the instability problem. However, the tyres suffer and wear more quickly because their alignment with the road surface has changed. The indie also remarked that the C-class is a relatively light car and it's easily deflected by strong side winds which also contributes to the instability issue.

REGARDS Phil

 

[clive williams]

Didn't MB have a problem of high speed lift at LeMans a couple of years back...

Only slightly! but they overcame it by calling it a plane.

My 500E is lowered as standard and has a nose down attitude. This contributes to its rock solid stability at high speed (>135mph). I understand Brabus used the W124 500E to achieve the current world record for aerodynamic efficiency from a production car.

Clive

500E
E320CDIT210

Clive

500E

 

[clive williams]

Hi All
..................
I inquired if this was a design fault? He said 'No'. He added that customers who complain can have their steering geometry adjusted (a recognized MB service) to almost eliminate the instability problem. However, the tyres suffer and wear more quickly because their alignment with the road surface has changed. The indie also remarked that the C-class is a relatively light car and it's easily deflected by strong side winds which also contributes to the instability issue.

REGARDS Phil

I wonder whether increasing the castor angle would improve things? You can buy adjustable roller bearing top mounts for the strut to increase the angle primarily of the castor but also the camber. It may mean that there will be some suspension harshness due to the roller bearing replacing the rubber squidgey thing. Is it worth trying?

Clive

500E
E320CDIT210

 

[philharve]

Hi All

Just had my very first 'A' service at a dealers. Cost me just over GBP300.00. The two rust spots I reported are stone chips they said. They used a small but powerful hand magnifier and a paint thickness gauge. I didn't witness the inspection though, so I think I'll get another opinion.

The car runs sweetly after the service. Mind you, it ran well before the oil and various filters were changed. The brake fluid was changed too. Braking is very powerful and reassuring, one of my cars' more striking traits.

Sped away from the dealers along a long straight in the direction of home. The straight gradually transforms into a long sweeping bend to the left and ends in a 90 degree righthander and crosses a narrow bridge. Went into the bend at 70 and the steering 'vagueness' appeared. Had to brake heavily to reduce speed to regain a degree of control otherwise I could see myself fish-tailing round the bend. Despite replacing the steering damper and ball joints earlier in the week, the car still misbehaves at speed. I think I'm going to have to look elsewhere for an explanation.

Coincidentally I asked the service manager what his opinion was of my indie's earlier comment that the C-class exhibits high speed instability. He agreed. Below a 100mph it should be fine, unless it's windy.

I'm now of the opinion that my 143mph car cannot attain these speeds unless you have the skill of a racing driver. I don't, but it hardly matters because I rarely have the urge to see 3 figures on the speedo'.

Do the road-burning Cs, the C43 and C36 also exhibit vague steering or is their steering geometry different to their more mundane cousins?

If a car is powerful it ought to have handling to match. If instability is not a design flaw (quote: indie), why is it present?

REGARDS Phil