993 tramlining
Discussion
I had cause yesterday to take the 993 on its first long journey during my 4 or so months of ownership (as opposed to taking out at weekends for a blast purely for the fun of it). Whilst it acquitted itself admirably in terms of being a mile muncher I did notice on the M6 and the A34 that the car seemed to tramline quite markedly when in the inside lane.
I realise that the main cause is of course that the inside lane is where the lorries live and they do tend to create their own tramlines in the road. But it seemed much more noticeable in the 993 than the S2000 I previously owned and had driven on the same roads. Is the car particularly susceptible to poor quality road surface? Or is it a function of something else?
Tyre pressures? (I haven't checked them for a while, so they could be out)
Suspension geometry/alignment needs attention?
A sign of tired suspension ore generally? I have only limited experience of driving other 993s so don't have much of a benchmark for how it should feel, but I'm increasingly coming to the view that the suspension has seen better days and could do with replacement. That's no great surprise at almost 80K miles, even though there's evidence that the rear dampers have both been changed in the past.
Is it a function of the tyre itself? I noticed yesterday that the fronts are different to the rears - P Zeros (Direzonale?)N2s on the front and P Zero Rossos N3s on the rear. Plenty of tread on both though.
It's not a major concern to me - really just curiosity on my part that prompted me to post this. I'm pretty ignorant about all things technical so those in the know will have to excuse the basic numpty questions!
I realise that the main cause is of course that the inside lane is where the lorries live and they do tend to create their own tramlines in the road. But it seemed much more noticeable in the 993 than the S2000 I previously owned and had driven on the same roads. Is the car particularly susceptible to poor quality road surface? Or is it a function of something else?
Tyre pressures? (I haven't checked them for a while, so they could be out)
Suspension geometry/alignment needs attention?
A sign of tired suspension ore generally? I have only limited experience of driving other 993s so don't have much of a benchmark for how it should feel, but I'm increasingly coming to the view that the suspension has seen better days and could do with replacement. That's no great surprise at almost 80K miles, even though there's evidence that the rear dampers have both been changed in the past.
Is it a function of the tyre itself? I noticed yesterday that the fronts are different to the rears - P Zeros (Direzonale?)N2s on the front and P Zero Rossos N3s on the rear. Plenty of tread on both though.
It's not a major concern to me - really just curiosity on my part that prompted me to post this. I'm pretty ignorant about all things technical so those in the know will have to excuse the basic numpty questions!
As you say tyre pressures could be out. As could alignment settings.
For road settings with even tyre wear and correct pressures you should not notice the effects of these motorway ridges more than any other car.
I have a moderate track setting on mine ,,,bit of -ve camber, rear toe in and run on road legal track rubber.....as I join the M25 to join the M1 I literally need to dial some lock in to continue in a straight line due to the ridges the elephant racers have left in the road.
Once you have the alignment set it should last a reasonable while on the road,,it tends to get knocked more out of true on trackdays,at least in my experience.
For road settings with even tyre wear and correct pressures you should not notice the effects of these motorway ridges more than any other car.
I have a moderate track setting on mine ,,,bit of -ve camber, rear toe in and run on road legal track rubber.....as I join the M25 to join the M1 I literally need to dial some lock in to continue in a straight line due to the ridges the elephant racers have left in the road.
Once you have the alignment set it should last a reasonable while on the road,,it tends to get knocked more out of true on trackdays,at least in my experience.
ek993 said:
Have you got standard wheels and tyre sizes on the car?
Yes - OEM 17" Targa wheels with the right size tyres. At least I think they're the right size - I'll check to be sure!
Thanks, CS - that tends to confirm my own thoughts. There wasn't much evidence of tramlining other than in lane 1, so I don't think it's a general problem - just wondered whether there was anything that might exacerbate the problem caused by the ruts.
A full geo alignment was in the budget for the next few months anyway, before this surfaced. It will be interesting to see whether that improves things.
Sounds like it must be the road but I would get the pressures checked asap and also sort out a full alinement. I do this every year/ time the tyres are changed. It's so easy to knock it 1-2 degrees out and your daily drive cover it up until you decide to get all Walter early one morning only to find it feels a sack of doggy doos.
PS you haven't even started to learn about tramlining untill you've driven a TVR in lane one of the A14 from Cambridge to Bury!
PS you haven't even started to learn about tramlining untill you've driven a TVR in lane one of the A14 from Cambridge to Bury!
hartech said:
Yes tyre pressures, geometry etc - but the front wishbones have a rubber silent block in them and it perishes and wears out and when it does the wishbones can move about a lot and result in tram lining - as well.
I would include checking them in your investigation.
Baz Hartech
I would include checking them in your investigation.
Baz Hartech
Wishbones or track rods where they attach to the rack?
Lurking Lawyer said:
Wishbone bushes, eh? Thanks - I'll have that looked into - it's in for its 48K service on Friday so I'll get Mike from Sports & Classic to have a look.
If they need changing, is it a big job?
If they need changing, is it a big job?
LL,
The official Porsche way is to change the complete wishbone rather than just the bushes. The wishbones are available from Porsche for about £160 each plus you have labour for fitting and the wheel alignment on top of this. Baz Hartech posted on here recently advising that he could supply rebushed wishbones on exchange. It may be worth looking in to this.
pp
Don't ask for an alignment as the suspension may need replacing anyway. A visual inspection and test drive by someone in the know should tell you this.
My car had 74,000 miles and original M033 springs and dampers on it (with 18" wheels). It felt OK, but tramlined a bit, was a bit crashy about town and it never inspired confidence at speed. Like you I didn't have anything to compare it to, but I did know that I wanted the car to be as good as new in this area.
I wanted a stiffer set up anyway so got new springs and dampers plus a few other replacement parts that the garage said needed doing, followed by a slightly more aggressive alignment settings.
The result is less tramling, much stiffer ride but superb confidence inspiring handling. For some reason, I keep thinking I should downgrade to 17" wheels, because I've convinved myself that they are much lighter and therefore better.
My car had 74,000 miles and original M033 springs and dampers on it (with 18" wheels). It felt OK, but tramlined a bit, was a bit crashy about town and it never inspired confidence at speed. Like you I didn't have anything to compare it to, but I did know that I wanted the car to be as good as new in this area.
I wanted a stiffer set up anyway so got new springs and dampers plus a few other replacement parts that the garage said needed doing, followed by a slightly more aggressive alignment settings.
The result is less tramling, much stiffer ride but superb confidence inspiring handling. For some reason, I keep thinking I should downgrade to 17" wheels, because I've convinved myself that they are much lighter and therefore better.
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