spacers cause vibration?

[23109VC]

i've thought about that, but the mileage is deceiving. The car never sits for more than a week at a time. I sometimes run it to work on Fridays, which means the car only goes 10-20 miles that day, then it sits for a week.... then I'll take it on a longer trip...but normally, it never sits more than 5-7 days before being moved...

If I did get flat spots from extended sitting - wouldn't that go away as the tires warm up, or if the car is driven for a few hours/hundred miles?

i'm wondering if it's more an alignment / balancing issue versus flat spots...

can a tire get a flat spot that is PERMANENT???

[blue2000s]

If your wheels are slightly out of balance, spacers can amplify it, as you're putting more of a thrust load on the wheel bearings. Could also be the spacers themselves.

[jmatta]

Modern radial tires don't get flat spots unless you've been tracking the car and locked your brakes up heavily; the true definition of "flat spotting".

I would get the car aligned with the spacers and have your wheels checked for balance.

I drive my car less than 3000 miles a year and never have a problem with tires, that doesn't go away as they warm.

[Adam]

Originally Posted by 23109VC

i've thought about that, but the mileage is deceiving. The car never sits for more than a week at a time. I sometimes run it to work on Fridays, which means the car only goes 10-20 miles that day, then it sits for a week.... then I'll take it on a longer trip...but normally, it never sits more than 5-7 days before being moved...

If I did get flat spots from extended sitting - wouldn't that go away as the tires warm up, or if the car is driven for a few hours/hundred miles?

i'm wondering if it's more an alignment / balancing issue versus flat spots...

can a tire get a flat spot that is PERMANENT???

So do you definately get vibration even after say an extended 20+ mile drive? It's not unusual for a tire to flat spot after sitting about a week. Some tires are worse than others. The Kuhmo XS tires I have on my car now flat spot slightly after only sitting a couple days. It can take 10-20 miles or so for them to completely round out especially in colder temps and they've been sitting for awhile.

[23109VC]

there is no vibration at lower speeds. it's only at higher speeds.

I took the car out this weekend and drove it about 150 miles. The vibration is there at various speeds. it seems like somewhere around 75-85 it would come on, but also seemed to come/go. it's not like at 75 it starts to vibrate and then woudl get worse and worse the faster I went..

i never notice it below 75. at 75 i feelt he steering wheel shake a little bit..not drasticlly as if I was driving over a washboard...but it was wiggling...as if it was unbalanced.

if I was accelerating, i noticed it less. not sure if that's because the problem is in the front and the weight came off the front wheels..but i'm guessing since i feel it through teh fronts, the problem is up front and when ih hammer it the weight moved ore toward the bck, so I felt it less...but that's what I noticed.

in general, the problem is only there at freeway speeds. i noticed it the most if I was just cruising, at a set speed...

i'll check the front wheels..maybe undo them, retorque them..see how that does.

maybe take the spacers out and try it again.

i distinctly remember when i fist put the spacers on, that I didn't notice any vibation problems... that was several months ago...

i'll experiment with various setups and report back

regardless of what i do, I AM going to look into roadforce balancing.

i went to the hunter website and it lists shops that have the new 9700 machine..or whatever their latest greatest machine is.

it also lists which sites have some special extra feature calld LFM / Straightrack.

is it important to have the car balanced with that LFM feature, or does it just matter to get it done by a place that has the newer 9700 machine??

there is an americas tire very close that has the 9700 but it does NOT hze the LFM feature. the only places near me that have the LFM feature are dealerships that don't do porsche work... chevy, mazda, etc.

will any shpo with a hunter 9700 be able to do "roadforce" balancing? the place that I got my tires balanced at did NOT have this machine, so my wheels did NOT get this type of balancing.

do I need this LFM feature? or is that unnecessary?

[Johnny Danger]

I believe that Porsche requires every one of its dealerships to have the Hunter road force balancing system in house. Also, there are a fair amount of independent shops and "tuners" that have their system as well.

p.s. If only you lived closer to the Northeast. I have a few sets of spacers that I would be more than happy to let you try. I am convinced, that at the very least it would improve your situation, if not remedy it altogether.

[Lil bastard]

Originally Posted by 23109VC

...is it important to have the car balanced with that LFM feature, or does it just matter to get it done by a place that has the newer 9700 machine??

there is an americas tire very close that has the 9700 but it does NOT hze the LFM feature. the only places near me that have the LFM feature are dealerships that don't do porsche work... chevy, mazda, etc.

will any shpo with a hunter 9700 be able to do "roadforce" balancing? the place that I got my tires balanced at did NOT have this machine, so my wheels did NOT get this type of balancing.

do I need this LFM feature? or is that unnecessary?

You probably just answered your own question. If your shop didn't have the Hunter machine - they didn't dynamically balance your tires - it may need to be done again.

The LFM feature is nice but not absolutely necessary; the 97XX system has done a very good job of dynamic balancing tires/wheels for a decade without it.

But, it's not just a case of the equipment, it's also a case of the operator.

To illustrate; I had a 4 wheel alignment done on my wife's Jag when we got new tires for it. I was allowed to be in the shop and observe. The tech spun the tires up, one at a time, on the 9700. This has a graphic readout and as I was watching, he turned off the machine while the graphic on the screen showed the 1st tire off. I commented and he said " The machine gives us a range and it's within that range..." I asked him to spin it up again and get it dead-on-balls which he did, and repeated for all 4 tires.

Next, the car went to the alignment rack. He did the setup and then started the machine. Because it's a Jag, I copied the alignment specs from the Workshop Manual and had them with me. The spec was 0.43. Again the tech adjusted it until it was at 0.47 and started tightening up the trailing arm. I pointed out that the spec was 0.43 and again the tech said the computer gives them a range of 0.39-0.49. I replied "that's just for schmucks who don't know what they're doing... but I bet you can get it right on the dot..." So he loosened the trailing arm and continued to adjust it until it sat squarely at 0.43 and set the other side the same way. I complimented him saying I knew he could do it. Anyway, that car can have a cup of coffee in the holder at 60 mph and it doesn't ripple.

These machines have universal software such as ALLDATA and such which do not always mirror the specs from the factory workshop manuals - remember these are commercial enterprises, it's counter productive to get things down to the Nth degree, they are built on the Move 'em in - Move 'em out principal. In most cases, this is fine, but with alignment and balancing, precision matters. So make sure you know what the correct specs are and have the tech prove to you that he's setting the car to those specs - despite what his database may say.

Cheers!

[Mark_T]

When I bought my '99 it had a vibration/shimmy that kicked in at around 70 mph. The problem was that the front tyres were badly cupped, probably from the previous owner running the wrong pressure. Plus he was running different brands of tyres front to back (where do these people come from?). I replaced all four tyres and I get no vibration at all at 125 mph.

Mark

[23109VC]

Originally Posted by Lil bastard

You probably just answered your own question. If your shop didn't have the Hunter machine - they didn't dynamically balance your tires - it may need to be done again.

The LFM feature is nice but not absolutely necessary; the 97XX system has done a very good job of dynamic balancing tires/wheels for a decade without it.

But, it's not just a case of the equipment, it's also a case of the operator.

To illustrate; I had a 4 wheel alignment done on my wife's Jag when we got new tires for it. I was allowed to be in the shop and observe. The tech spun the tires up, one at a time, on the 9700. This has a graphic readout and as I was watching, he turned off the machine while the graphic on the screen showed the 1st tire off. I commented and he said " The machine gives us a range and it's within that range..." I asked him to spin it up again and get it dead-on-balls which he did, and repeated for all 4 tires.

Next, the car went to the alignment rack. He did the setup and then started the machine. Because it's a Jag, I copied the alignment specs from the Workshop Manual and had them with me. The spec was 0.43. Again the tech adjusted it until it was at 0.47 and started tightening up the trailing arm. I pointed out that the spec was 0.43 and again the tech said the computer gives them a range of 0.39-0.49. I replied "that's just for schmucks who don't know what they're doing... but I bet you can get it right on the dot..." So he loosened the trailing arm and continued to adjust it until it sat squarely at 0.43 and set the other side the same way. I complimented him saying I knew he could do it. Anyway, that car can have a cup of coffee in the holder at 60 mph and it doesn't ripple.

These machines have universal software such as ALLDATA and such which do not always mirror the specs from the factory workshop manuals - remember these are commercial enterprises, it's counter productive to get things down to the Nth degree, they are built on the Move 'em in - Move 'em out principal. In most cases, this is fine, but with alignment and balancing, precision matters. So make sure you know what the correct specs are and have the tech prove to you that he's setting the car to those specs - despite what his database may say.

Cheers!

you are likely VERY right about that. WHERE it goes is just as important and wha tmachine they use. you can use the correct machine, but if th tech just figures it's "close enough" and doens't make it exact - you get a "close enough" result...

i'll find a shop that does performance car alignments, or maybe take it to the dealer for this one. i know the local Porsche dealer DOES have the Hunger 9700....and if I make a fuss, i"m sure I can get them to do it "RIGHT"....

[Johnny Danger]

Originally Posted by 23109VC

you are likely VERY right about that. WHERE it goes is just as important and wha tmachine they use. you can use the correct machine, but if th tech just figures it's "close enough" and doens't make it exact - you get a "close enough" result...

i'll find a shop that does performance car alignments, or maybe take it to the dealer for this one. i know the local Porsche dealer DOES have the Hunger 9700....and if I make a fuss, i"m sure I can get them to do it "RIGHT"....

What is the verdict on the front 7 mm spacers ? Are they hubcentric or not ?

[manolo]

I have the 7mm/14mm spacers on my 986S. They are hubcentric. The picture shows the outside of the rear and the inside of the front. Its hard to tell but the inside has a bevel to accomodate the stock hub, then a ring on the outside for the wheel. Other than name, they are very comparable to H&R and not cheap cast aluminum knock offs like a lot of the "billet" parts out there.