: OK here's a weird one



Castro
12-14-10, 02:38 PM
I took my car in to get my snow tires mounted yesterday, I went with a set of Pirelli Sottozeros based on reviews that these are more of a "high performance" snow tire, and the fact that they weren't horribly expensive. I also had them install my driveshaft coupler while it was there. I picked up the car and took it for a nice run following my boss who drives pretty fast, we went on some nice back roads and the tires felt pretty good, not too noisy, felt ok in the corners but they're brand new so I wasn't pushing hard. The new coupler seemed fine, reduced the clunk a bit as expected but not overly noticeable. Overall it felt like it was running great, smooth, no issues.

This morning I drove to work and got a strong vibration in 3rd that went away at 30mph. It was creepy, the shifter was vibrating badly and when I hit the clutch it was still there. I was worried but drove the rest of the way there, found that I could drive through the problem and it would go away. Then when I left for lunch it seemed like it was gone, at least nowhere near as bad. Driving back to the office it's back but also not as bad. It's cold today (20ish), the car sleeps in my garage and sits in the parking lot at work.

Recently I've had a tune up, plugs, wires, oil, trans fluid, clutch fluid, diff oil. Any thoughts on what it could be? There is no grinding, no squealing or anything, and it never happened before. It only occurs from maybe 20-30mph, and as I said it's off and on. I'll drive around a bit after work and let it warm up, drive to work is only 5 minutes.

CadzillaTN
12-14-10, 03:12 PM
I vote for a bad balance job on one of the tires, cold tire(s), or, the hockey puck is too stiff..

Twitch
12-14-10, 03:36 PM
Did they remove the driveshaft to install the coupler? It needs to be put back the same way. Just a thought.

Tony

BigJeff
12-14-10, 03:54 PM
How cold does it get in your garage? I'm thinking the new tires are flat spotting over night. My summer tires would act similar in cold weather until they warmed up, then the problem would go away...Just a thought

Twitch
12-14-10, 05:37 PM
How cold does it get in your garage? I'm thinking the new tires are flat spotting over night. My summer tires would act similar in cold weather until they warmed up, then the problem would go away...Just a thought
Good point,,,,,that would REALLLLLY suck though :mad:

Castro
12-14-10, 06:03 PM
Thanks for the replies, I'll see how she acts tonight. My garage is not very warm in winter, maybe I can drive onto a nice warm blanky every night for my sensitive little snow tires.

BigJeff
12-14-10, 06:51 PM
Thanks for the replies, I'll see how she acts tonight. My garage is not very warm in winter, maybe I can drive onto a nice warm blanky every night for my sensitive little snow tires.

Funny! Hopefully you get it figured out.....

Stepside
12-14-10, 07:46 PM
So, what is the air pressure in the tires on a below 32*F day?

Has anyone noticed that some tires say, '44'psi max' and some say, '51'psi max.

I think some tires need higher pressure. What's written on your sidewall?

MKWAGON
12-14-10, 10:09 PM
Do you have snow on the road? Could be some build up on one or more rims throwing it out of balance. At some point it'll get thrown and things will smooth out again.

kevm14
12-14-10, 11:25 PM
Aside from snow I've never seen a wheel balance issue manifest at only 30mph. So I vote possible flat spots, possible driveshaft issue or even possible flywheel issue. Does it have anything to do with rpm or is it strictly speed related?

D3l7a3ch0
12-15-10, 02:08 AM
I drove away from a tires plus once, with all of my lug nuts loose on one wheel. people can forget to do things when they're busy drooling over a CTS-V

Castro
12-15-10, 10:21 AM
I drove around last night for a while and it definitely subsided. This morning it's back. I don't think it's rpm related it seems to be 22-30mph only. After everything was up to operating temp last night it was pretty much gone?

Jon
12-15-10, 12:06 PM
You most likely had snow built up on the inside of the rim. Can cause some crazy vibrations. It'd explain why it went away as well.

Castro
12-15-10, 01:17 PM
Nope no snow yet it was dry. Next week we should see some accumulation though. I'm gonna call the shop and ask if they indexed the drive shaft.

YoshiV
12-15-10, 02:49 PM
My Sotto's are on their 3rd winter season and have never had flat spot issues after sitting. Car is garaged at night and sits out during the day.

I live in Cleveland where it gets plenty cold, below 20 the last few days.

Castro
12-15-10, 04:26 PM
Thanks Yoshi, I think the tires can be ruled out at this point since it's such a narrow window- I assume if they were flat spotted you'd notice at lower/higher speeds as well. It seems like if I get on it hard and apply torque it goes away for the rest of the trip... anyone with drivesaft vibration experience care to chime in? The 22-30mph window is just weird to me I don't get it.