Andy Roe

Adrian,

The C4 understeers, and the C2 tends to oversteer more. By putting larger tyres on a C4, you are providing more grip up front in an effort to combat the understeer. If you do this in a C2, it will encourage even stronger oversteer characteristics!

Andy

Roygarth

Why?

Like Manuel 'I know nothing', I know it's true but I've never understood why this is? With power to front wheels I would have thought they would drag the front round better than a C2?

DaveK

I assumed that if your drive is fully from the rear wheels then the back is trying to push out all the time, and this accounts for the oversteer. With some drive to the front wheels, I don't think they try to drag the front round - they are being driven and actually want to drive straight on.

However - I am making all of the above up and also no nothing.

Incidentally - I think driving 964s fast is irresponsible and would never do it myself. Although if I did, I am sure my car would be / was very stable indeed.

pzull

Wouldn't that be side windows bending out since air rushing outside results in lower pressure than static air inside?

Andy Roe

Front wheel drive cars produce lots of understeer. Rear wheel drive cars appear to produce lots of oversteer. Thus, our C4's should handle perfectly!

Isn't one of the reasons why the C4 understeers, down to the rear differential locking up?

Phil Raby

No, the low pressure inside the car is caused by John's sharp intake of breath as he's astounded by his car's performance

pzull

Car's smooth below and above 100mph (160kmh). But in the narrow band of 160-165 kmh I get vibration going through the steering and the car - not violent just like a vibrator....serious. Above that it goes all smooth again.

I've got Ruf suspension as well it's too soft at speed on B-roads and above 125mph it feels like it's floating if I hit road undulations.

Car is lowered and has front spoiler

DaveK

Also got RUF suspension.

Funnily enough - I experienced vibration a bit like you mention while driving around France. It seemed to be tied to a particular rev range - yet it's never done it since, so I guess it was the road surface.

bikeaddict

I've got a C2 and on stock wheels and tires I think it's more prone to understeer at speed and oversteer under extreme power at low speeds ( my wife actually spinned around a corner the first time she drove it .... dammit!). I had a WRX AWD and it understeered like hell but you could drop the throttle to get it to tighten up and drift. Seemed to work on my C2 as well but I was really actually looking forward to the oversteer of the 911 and was a bit disappointed. I've gone to 225/18's in front and 255/18's in back so maybe this will get some more neutrality or possibly oversteer that I'm looking for.

Experiment in progress..........

Arjan B.

I drive often in Germany, on safe autobahn on top speed.
Car feels fine at all speeds, also on top speed is stability no problem. Even the brakes work excellent if you need them the hardest.
Top speed is for me aprox 170 miles an hour with the drilled air filter and cup exhaust.
The humming noice from the air intake and exhaust dissapears obove 155 miles per hour. Then it's getting pretty quiet inside.......

I have the stock tire sizes which fit on the Cup 17", and they are Bridgestone s02's.
Even on track, the car handles great, and without any bugs.

BGLeduc

I have 205/255 on 17's (7.5/9) on my lowered US spec C2.

The 255's on the rear do not rub anywhere. The 205's in front will foul the inner fender at full lock. I did NOT do the steering stops, which is why I still get a small amount of rub.

Not sure about a 225 in front on the wide 17's. I do run a 225 on my 6" 16's for track/autocross work, and they too foul the inner fender at full lock.

BGL

Doug H

My car is silky smooth and completely stable. It could be a combination of spoiler and suspension, but it seems more stable, smooth and firmly planted than my other cars at speed.

The only thing I don't like is the windows sills on the back edges need to be replaced and have wind noise at speed. I heard this was a PIA and somewhat costly job.

Gilbasa

I was driving to Northern California last summer on I-5 tooling around with another traveler in a brand new Mercedes SL 500 doing around 90-100mph. when all of sudden we found our selves looking down a ten mile traffic free straight stretch. I took the lead with the Merc. not far behind. We got up to about 140 mph when the SL chickened out, I still had plenty of free open space ahead of me and decided this would be a good time to see how fast I could push my stock 1990 964. Before I knew it my speedo was at 160mph and I stood on it until just under 165mph at 164mph. I felt (according to the speedo) I could get 170mph out of the car, but thoughts of a blow out, told me I better reel things back in. Aside from a little wind noise the car was as smooth as silk at that speed. The steering felt comunicative and direct and at no time did I feel I was out of controll. I belive these cars are made for that speed on the autobahn and had the car had more power it would feel very comfortable at 190mph. When I finally came back down to what seemed like a crawling speed of 90mph (which felt like I could hop out and jog along side my Porsche) The guy in the Merc. caught back up to me and gave me a big thumbs up. I'ts nice to know that this 14 year old 964 with 124k miles on it can still comand respect from the driver of a 2004 Mercedes SL 500.

To answer your question...Yes, these cars are very stable at high speeds completely stock, 14 years old with a few miles under the belt. let me know if I can answer any other questions about how the car felt at high speeds.

Thank you,

Gilbasa

I was driving to Northern California last summer on I-5 tooling around with another traveler in a brand new Mercedes SL 500 doing around 90-100mph. when all of sudden we found our selves looking down a ten mile traffic free straight stretch. I took the lead with the Merc. not far behind. We got up to about 140 mph when the SL chickened out, I still had plenty of free open space ahead of me and decided this would be a good time to see how fast I could push my stock 1990 964. Before I knew it my speedo was at 160mph and I stood on it until just under 165mph at 164mph. I felt (according to the speedo) I could get 170mph out of the car, but thoughts of a blow out, told me I better reel things back in. Aside from a little wind noise the car was as smooth as silk at that speed. The steering felt comunicative and direct and at no time did I feel I was out of controll. I belive these cars are made for that speed on the autobahn and had the car had more power it would feel very comfortable at 190mph. When I finally came back down to what seemed like a crawling speed of 90mph (which felt like I could hop out and jog along side my Porsche) The guy in the Merc. caught back up to me and gave me a big thumbs up. I'ts nice to know that this 14 year old 964 with 124k miles on it can still comand respect from the driver of a 2004 Mercedes SL 500.

To answer your question...Yes, these cars are very stable at high speeds completely stock, 14 years old with a few miles under the belt. let me know if I can answer any other questions about how the car felt at high speeds.

Thank you,

eddychan

Great Stuff! well done Gilbasa!
I wish we have the road and space here in Hong Kong!!!!
I managed 150kmh this morning and it was totally illegal and boy how I wish I had more road space and less cops/gatso!!!

Eddie