Steering wheel shudder

[tboo]

I just started to notice that when Im doing ~70mph the steering wheel starts to shudder or shake slightly. The thing that is weird is that its an on/off type of shudder. it shakes for about 3 seconds then goes away for about 7 seconds & then comes back again continuing the cycle.

Again this only does this around 70mph. Any ideas?

2002 Boxster, manual, 18 Turbo look wheels.

Thanks

[Tool Pants]

I went through the same thing at the same speed 5 few years ago when we were all new. I thought it had to do with the spoiler going up at about 75mph, because after that speed it would go away.

New tires and a balance and it was gone.

[SFBayArea Jimmy]

Do you have P-Zeros? If so, sorry but it's time to get new shoes.

[Tool Pants]

Original tires from the factory were continential. Replacement is sumitomo. For my Boxster. No N rating on the replacement tires.

[Kevin369]

Tool Pants:

What Sumitomos did you get and from where? I'll be in the market for new kicks for my Boxster soon. (Notwithstanding my coolant issue.) I've been looking at alternatives to the big names, like Sumitomo and Falken.

[Tool Pants]

They are Sumitomo HTR Z II from TireRack. Got them 3 years ago and they were $500 for the set of 4, then had a local wheel place mount them. Good bang for the buck, but not fantastic in the wet. I have about 20,000 miles on them. They are not N rated but I could care less.

[Highlander]

I've been looking at alternatives to the big names, like Sumitomo and Falken.

Another decent tire that gives great "bang for the buck" is the Kumho Ecsta 712. Better tire but a little more expensive is the Kumho Ecsta MX.

Edited June 23, 2004 by Highlander

[tboo]

Do you have P-Zeros? If so, sorry but it's time to get new shoes.

My tires are Continental Sportcontact 2s. Car only has 7300 miles-tires look like they have more

[Tool Pants]

I think I will try Kumho next time. They also have good reviews. I can always put on the N rating.

Always wondered what it would be like 20 years from now and no tire company made N tires for an old Boxster. If your are old then you may remember the 1980s Ford Mustang and the TRX wheels.

Always wondered when this N rating thing started and why. Apparently in 1985.

http://www.nichols.nu/tip493.htm

[Lux]

There's usually 2 things that will make the shudder (and it only happens between 65-70mph, not under and not above).

1. Wheels are not hubcentric. A lot of aftermarket wheels are not hubcentric so as to make the wheels fit a variety of cars. Usually they will provide a "ring" to place inside the wheel hub to match up with your car. Without this, it is impossible to "center" your wheel, thus causing vibrations around 70mph.

Since you mention you have the Turbo wheels, I'm guessing they are factory and not aftermarket. Therefore, they should be hubcentric. If they are aftermarket clones, then I'm 99% sure that this is your problem.

2. Tires and/or wheels are out of round. Are the tires new? Did it just start doing this? Was your car parked for a long time and developed a flatspot? Regardless, sometimes a "speed balance" will help.

-BlackBox

[Kevin369]

I've been looking at alternatives to the big names, like Sumitomo and Falken.

Another decent tire that gives great "bang for the buck" is the Kumho Ecsta 712. Better tire but a little more expensive is the Kumho Ecsta MX.

Thanks Highlander. I had also looked into the Kumhos as well but didn't know/find out much about them. Most people would just go with a SO-3 or a Michelin Pilot Sport, which are great tires but hella expensive.

I occasionally track my car and autocross it. Do you think the 712's will suffice?

My problem right now is debating whether I want to get 18" wheels to go with the new tires. I mean now is the time if I'm going to buy new tires, right? ;) I'd love a set of the Carrera Lightweights but they are pricey.

Edited June 24, 2004 by Kevin369

[jaygo44]

If your looking for a less expensive tire to replace your P-Zero's Try Kuhmo KU19 tires, they are Assimetrico, just like the p-zero, and just like our cars need. I was told that the tire last about 50% more than the p-zeros and becuase they are assimetrico the sidewalls are thcker than regular, but still not N rated. Also they seem to be wider than the p-zero's they fill out my rims about 1/2' more, also protects my rim more. I have stock turbo 18's but use my RH 3.6 turbo 3 piece wheels most of the time. These rims have a huge lip that the p-zeros just could protect and the kuhmo's fill them right up.

I have had them for 3 months and they grip very very well, no real differnence than the p-zero and the are very good in the wet, I would say better than the p-zero's in the rain. I got them from tire rack for about $670 for the set of 18's

AS far as the Shudder problem, read the above, I had that problem with my aftermarket 3 piece 3.6 turbo wheels and they turned out to be out of round and are out gettting fixed as I write this, or you need a good balance and/or new tires.

Good luck! :drive:

Edited June 24, 2004 by jaygo44

[tboo]

Thanks for the input guys! Im having them balanced tomorrow