Good vibrations!
Discussion
Morning all!
Just a quick question re a vibration in the 996.
I am pretty certain its the tyres but thought i would ask.
Lower speeds (up to 120) all is well, but after that a vibration starts through the car.
If I am honest, I am not happy with tyres anyway (Rosso N4s)-While the tread is OK (5mm front, 3mm rear) , when you buy a second hand car you never really know how old they are, and that uncertainty is compounded by the fact when I collected it I checked the pressures at the first petrol station and they were all well below what they should be. There are also some mighty recent scuff marks on the front wheels, that surely must have also damaged the tyre in the process.
(I had a proper geo done, wheel balance and all suspension checked etc as soon as I got the car as a matter of course)
So I am ordering a new set anyway, but is it likely the old ones are the source of this vibration?
Just a quick question re a vibration in the 996.
I am pretty certain its the tyres but thought i would ask.
Lower speeds (up to 120) all is well, but after that a vibration starts through the car.
If I am honest, I am not happy with tyres anyway (Rosso N4s)-While the tread is OK (5mm front, 3mm rear) , when you buy a second hand car you never really know how old they are, and that uncertainty is compounded by the fact when I collected it I checked the pressures at the first petrol station and they were all well below what they should be. There are also some mighty recent scuff marks on the front wheels, that surely must have also damaged the tyre in the process.
(I had a proper geo done, wheel balance and all suspension checked etc as soon as I got the car as a matter of course)
So I am ordering a new set anyway, but is it likely the old ones are the source of this vibration?
I'd always suggest a geometry check AFTER having the tyres done rather than before.
The age of a tyre is easy to check - look for an embossed lozenge shape with four numbers on it, the week and year of manufacture are marked - eg: 3611 ~ manufactured in the 36th week of 2011.
If any of the tyres have been run low on pressure the shoulders may have been damaged giving you the vibration.
Its worth mentioning that the rears generally tear up on the inner edges by the time the rest of the tyre has got to 3mm - I've seen them run through the canvas and wire layers in patches fairly regularly; check to be sure.
The age of a tyre is easy to check - look for an embossed lozenge shape with four numbers on it, the week and year of manufacture are marked - eg: 3611 ~ manufactured in the 36th week of 2011.
If any of the tyres have been run low on pressure the shoulders may have been damaged giving you the vibration.
Its worth mentioning that the rears generally tear up on the inner edges by the time the rest of the tyre has got to 3mm - I've seen them run through the canvas and wire layers in patches fairly regularly; check to be sure.
bull996 said:
Morning all!
Just a quick question re a vibration in the 996.
I am pretty certain its the tyres but thought i would ask.
Lower speeds (up to 120) all is well, but after that a vibration starts through the car.
If I am honest, I am not happy with tyres anyway (Rosso N4s)-While the tread is OK (5mm front, 3mm rear) , when you buy a second hand car you never really know how old they are, and that uncertainty is compounded by the fact when I collected it I checked the pressures at the first petrol station and they were all well below what they should be. There are also some mighty recent scuff marks on the front wheels, that surely must have also damaged the tyre in the process.
(I had a proper geo done, wheel balance and all suspension checked etc as soon as I got the car as a matter of course)
So I am ordering a new set anyway, but is it likely the old ones are the source of this vibration?
Well, the tire balance is always suspect. As tires wear they can go out of balance and need re-balancing. A shop might not be inclined to balance older tires for a number of reasons and while it is hard to believe a shop would lie to you...Just a quick question re a vibration in the 996.
I am pretty certain its the tyres but thought i would ask.
Lower speeds (up to 120) all is well, but after that a vibration starts through the car.
If I am honest, I am not happy with tyres anyway (Rosso N4s)-While the tread is OK (5mm front, 3mm rear) , when you buy a second hand car you never really know how old they are, and that uncertainty is compounded by the fact when I collected it I checked the pressures at the first petrol station and they were all well below what they should be. There are also some mighty recent scuff marks on the front wheels, that surely must have also damaged the tyre in the process.
(I had a proper geo done, wheel balance and all suspension checked etc as soon as I got the car as a matter of course)
So I am ordering a new set anyway, but is it likely the old ones are the source of this vibration?
I do recall on this board some months ago an owner had a vibration issue with his car and the short version of the story is after going back to his fave shop more than once, he went to another shop which did an alignment and found the alignment off. afterwards the symptoms were gone. The indication is the first shop simply blew this guy off.
Now, I have run into a mild vibration that occurs at speed (above 75mph but I'm not saying how much above but above, we'll leave it at that...) that proved to be due to too much air pressure in the front tires. The air pressure wasn't that much higher that what was called for but upon dropping the pressure down to the factory pressure with the tires cold the vibration went away.
If the tires have significant scuff marks there's a chance the sidewalls are damaged. The tires might balance ok but at speed exhibit symptoms of being out of balance.
If the wheels are curb rashed the wheels could be out of true. Depending upon the quality of the balance job the tech may not have noticed the wheels showing signs of excessive run out. As long as he can get the balance close enough that might be the extent of his concern.
If I read your post right you're getting new tires installed. Let's see how the car feels after new tires are installed and balanced.
Sincerely,
Rockster.
bull996 said:
when you buy a second hand car you never really know how old they are
aye you do, there's a little circle with four digits on every one, say like 0408.If a tyre had that stamp (0408) then it was manufactured in April 2008. Doesn't tell you when they were fitted mind or how many miles they've done but you can see when they were made.
For reference swmbo's beetle is needing new rears, it's an 07 plate & they're original (car has done 25k miles) & about 3mm depth, tyres are perishing inside the treads so are getting changed this month but realisticly that's all you'll get out of a set of quality tyres (hers are sport contacts).
As for your problem, if the wheels are vibrating above 120mph (did I read that right?) I'd guess it's a simple balancing problem. If they were fitted at a local tyre shop they've provably just been roughly balanced with a 60ish mph "sweet spot".
I wouldn't necessarily bin the tyres just yet, check the manufacturer date & go from there....
I had a similar issue with the Spyder.
I bought it in Jan 2010 with 900 miles on it and fitted with GoodYears - the performance of the tyres was faultless except for balancing issues. Even after changing the rears at 15,000 miles - still the same issues with balancing with no other faults found in the suspension/geo etc.
A couple of months ago we changed all 4 tyres to Bridgestone and the balancing issues = SOLVED.
Good Luck
khushy
I bought it in Jan 2010 with 900 miles on it and fitted with GoodYears - the performance of the tyres was faultless except for balancing issues. Even after changing the rears at 15,000 miles - still the same issues with balancing with no other faults found in the suspension/geo etc.
A couple of months ago we changed all 4 tyres to Bridgestone and the balancing issues = SOLVED.
Good Luck
khushy
LaurasOtherHalf said:
If a tyre had that stamp (0408) then it was manufactured in April 2008. Doesn't tell you when they were fitted mind or how many miles they've done but you can see when they were made.
That would mean that I've got a tyre on my Audi made in the 48th month of 2011 
It's week and year, so 0408 would mean week 4, 2008 i.e. end of January. They can then be in the supply chain for up to a year I guess (sometimes more) before being fitted.
Callughan said:
When I first bought my C4S, it would also vibrate at high speeds. The front discs were changed which helped but when they changed the steering rod it cured it. All done under warranty.
You need to take it to a Porsche specialist for inspection
I keep trying to get it to Mike at Sports and Classic, but I havent had the time yet and am off to India next week, so will have to be done when I get back.You need to take it to a Porsche specialist for inspection
bull996 said:
Callughan said:
When I first bought my C4S, it would also vibrate at high speeds. The front discs were changed which helped but when they changed the steering rod it cured it. All done under warranty.
You need to take it to a Porsche specialist for inspection
I keep trying to get it to Mike at Sports and Classic, but I havent had the time yet and am off to India next week, so will have to be done when I get back.You need to take it to a Porsche specialist for inspection
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