gmonsen

My 3.6 has speedline 18x10 and 18x11 on it, although I have the original 18x9 and 18x10 wheels. The car is a bit lowered and the combination is deadly when I hit the lane where the trucks have worn it down. It hunts and reacts nway too quickly to road surface. Is the problem the alignment or the wheels or both (probably)? Any comments would be appreciated... -Gordon

Adrian

Dear Gordon,
First of all the orignal fronts are 8JX18. The problem you have is called tramlining and I am afraid you have to get used to it. This is a direct result of the 18 inch wheels and low profile tyres mixed with your suspension modifications. The system you have I know nothing about but I cann assure you that you have to learn to get used to it because there is nothing you can do about it. The problem is worse on US models of the Turbo 3.6 unless you modify the rear end to match that of the ROW version. However this only reduces the problem slightly. All 964s running on 18 inch wheels tramline like crazy on the road surfaces you are using.
Ciao,
Adrian
911C4

Ade - C4 91

Hi

I'm sure that Adrian is probably right - with 18" you may have to live with some tramlining, but there are a few other things that may be exaggerating the tram lining (even on standard 964) - these being your tyre choice and the amount of front end toe in you have.

Firstly - what tyres are you using?

Some tyres are highly direction and feel very fidgety and unstable on a 964. For example I've recently tried N3 P-Zeros and they proved to be so bad with tramlining and instability that I swapped them for ContiSport Contact 2’s, - which without any further alignment changes - completly eliminated the tramlining.

Alignment is very important on these cars. A little too much Toe-in can cause very bad tramlining - so try to get a good alignment done by someone who knows what they are doing with 964’s.

Good luck

Ade

gmonsen

Thanks and sorry for the stock wheel size faux pau. Adrian, are you saying that going back to the stock wheel widths is NO help? I would have thought the 8 inch fronts would have less bite and therefore less tramlining? No? What about tires? There are Bridgestone So3's on it now. What about Kumho's or Yokohama's?

I will check the alignment. The car is lowered "a bit", but I don't know how much. I am going to have the suspension gone over by Peter Dawes Motorsports in the next few weeks. Peter drove the car and said it makes an awesome club racer, but I want him to dial it back to a commuter. Adrian, as you say, the ropads are the problem. Where I livce they are pretty OK, but as I drive from Pennsylvania through New Jersey into NYC the roads become hellish. Not a smooth bit anywhere. Just a good upper torso workout. No cell phone and coffee here.

Gordon

Adrian

Dear Gordon,
The prime cause is the tyre profile. If you can increase the profile height with the narrower wheel width this will help a little but please believe me when I say I have driven more than one 964 based products, Porsche and RUF with 18 inch wheels with various combinations of wheel widths, wheel alignments (agressive to standard), tyre profiles and tyre brands and they all tramline. The bad roads will never help either.
Ciao,
Adrian
911C4

FRUNKenstein

I have read in several other threads that 18" wheels and 964's just aren't a good combination. Mine's a 1990 C2. Are 17" wheels prone to the same problems? I was thinking of replacing my stock 16" design 90's with some 17" "turbo twist" (I can't remember the real designation for them off the top of my head). Will this result in significant compromise in ride and handling? If not, I probably won't make the switch as it is really just a switch for appearance sake.

Adrian

17 inch wheels and a lower profile tyre will introduce tramlining. Nowhere as bad as the 18 inch wheels but it will occur. On a scale,
16 inch wheel and standard tyre profile, no tramlining.
17 inch wheel and standard but lower profile tyre, tramlining occurs especially on a cold road surface.
18 inch wheel and even lower profile tyres, variable tramlining which gets really bad on rutted road surfaces.
Ciao,
Adrian
911C4

gmonsen

This is good. Ade, I will consider the Conti's. Didn't even know they were still in business. Remember them coming on my new 1974 2002...

Adrian, while the wheel diameter obviously effects the tramlining a lot, since it reduces the tire section, the reason I thought it would be helped somewhat going to the narrower width original wheels was that the tires themselves are not "width specific". So, when you put an 18x265x35 on an 18x10 in wheel, the aspect ratio should be lower than the same tire on an 18x8 inch wheel. No?

I would suppose that I could get matching Speedline 17x9 inch for the front and get the ride height adjusted?

Anyway, I think I will try a different tire on the smaller 18's and get it aligned at Dawes Motorsports. Thanks... Gordon

scupper

I am running 17 inch wheels with Perelli P-Zero, N2 tires and tramliining is minimal - Only on certain, poorly maintained city streets is it noticeable, but it's not bad. I get none on the highway at speed.

(BTW, car is lowered with Bilsteins and H&Rs)

In contrast, my old 83 SC, that had also been lowered, was all over the road with 16 inch wheels. But lowering an SC changes the geometry causing other problems, like bump steer. The lowered C2 is such a pleasure to drive - there is no comparison.

Chuck
93 C2