06-11-2019, 07:37 PM
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#1
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Registered User
Join Date: Nov 2018
Location: NY Suburbs
Posts: 339
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Intermittent Shimmy ??
Is that really possible? Just bought of new set of tires. Michelin Pilot Sport A/S 3+. Were balanced on a road force balancer and mounted at a top notch Porsche indy shop Car drives so much nicer. But occasionally I get this very noticeable shimmy at 75 - 85 mph. Most of the time it's not there, but it happens sometimes.
Any thoughts?
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2004 Boxster S, 6 spd, Triple Black
1986 944 Turbo (sold in 1988)
Since then, a 300ZX, a few BMW 3 Series, a few VW's
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06-12-2019, 03:27 AM
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#2
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Who's askin'?
Join Date: Mar 2018
Location: Utah
Posts: 2,446
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Loose steering gear?
Bad ball joint?
Bad tie rod?
Bad wheel bearing?
I'd be checking front end parts, is what I'm saying.
The other possibility: does this occur at the same place each time? (I have a specific spot in my commute where the grooves in the paving cause a front end shake)
Sent from my SM-G970U using Tapatalk
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06-12-2019, 05:59 AM
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#3
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Registered User
Join Date: Jan 2014
Location: New Jersey
Posts: 1,631
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How was the car before the new tires were installed? If you had the shimmy on the old tires, and everything else checks out, it could be that one of your wheels is bent so slightly that it isn't visible to the naked eye but still results in a shimmy. The places that repair and true wheels use dial indicators to check trueness in both up and down and side to side. I had all 4 of my wheels trued while they were being refinished, and my car is now the smoothest it's ever been. Of course I went to an HPDE a couple of weeks ago and now my tires' treads are coated in race rubber with stones stuck to them, so that all needs to wear off to get the smoothness back!
__________________
Current: 2022 718 Cayman GT4, PDK bone stock (the dark side).
Former: 2003 S, 3.6 LN Nickies, ARP rod bolts, under-drive pulley, Fabspeed sport headers, Softronic tune, 987 airbox 987 motor mount, Function-First Sport motor mount insert, Ben's short shifter, Nine8Six projector headlights & center caps, ROW M030, stainless flexible brake lines, B-K rollbar extension & fire extinguisher mount, hardtop
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06-12-2019, 07:45 AM
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#4
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Registered User
Join Date: Nov 2018
Location: NY Suburbs
Posts: 339
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Quote:
Originally Posted by PaulE
How was the car before the new tires were installed? If you had the shimmy on the old tires, and everything else checks out, it could be that one of your wheels is bent so slightly that it isn't visible to the naked eye but still results in a shimmy. The places that repair and true wheels use dial indicators to check trueness in both up and down and side to side. I had all 4 of my wheels trued while they were being refinished, and my car is now the smoothest it's ever been. Of course I went to an HPDE a couple of weeks ago and now my tires' treads are coated in race rubber with stones stuck to them, so that all needs to wear off to get the smoothness back!
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Wouldn't a Roadforce balancer detect a wheel that's not true? And also, if that were the problem, why would it happen intermittently?
__________________
2004 Boxster S, 6 spd, Triple Black
1986 944 Turbo (sold in 1988)
Since then, a 300ZX, a few BMW 3 Series, a few VW's
Last edited by BoxMann; 06-12-2019 at 07:59 AM.
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06-12-2019, 07:47 AM
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#5
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Registered User
Join Date: Nov 2018
Location: NY Suburbs
Posts: 339
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Quote:
Originally Posted by maytag
Loose steering gear?
Bad ball joint?
Bad tie rod?
Bad wheel bearing?
I'd be checking front end parts, is what I'm saying.
The other possibility: does this occur at the same place each time? (I have a specific spot in my commute where the grooves in the paving cause a front end shake)
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I understand that those worn parts could cause a shimmy, but why would it happen intermittently? Wouldn't it happen consistently? And the shop (and PPI) inspected all of that and said everything looks good. And the car was aligned very recently. Those problems would have shown up on an alignment.
And it occurs on different roads.
__________________
2004 Boxster S, 6 spd, Triple Black
1986 944 Turbo (sold in 1988)
Since then, a 300ZX, a few BMW 3 Series, a few VW's
Last edited by BoxMann; 06-12-2019 at 07:57 AM.
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06-12-2019, 07:58 AM
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#6
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Need For Speed
Join Date: Feb 2013
Location: Funville
Posts: 2,112
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Get the car aligned.
__________________
2003 Boxster S
| 987 Air Box | K&N Air Filter | 76mm Intake Pipe| 996 76mm TB | 997 Distribution T | Secondary Cat Delete Pipes | Borla Muffler | NHP 200 Cell Exhaust Headers |
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06-12-2019, 08:06 AM
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#7
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Registered User
Join Date: Nov 2018
Location: NY Suburbs
Posts: 339
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Quote:
Originally Posted by KRAM36
Get the car aligned.
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The car was aligned 30 days, 400 miles ago, by a top notch Porsche indy shop.
__________________
2004 Boxster S, 6 spd, Triple Black
1986 944 Turbo (sold in 1988)
Since then, a 300ZX, a few BMW 3 Series, a few VW's
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06-12-2019, 08:13 AM
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#8
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Need For Speed
Join Date: Feb 2013
Location: Funville
Posts: 2,112
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Quote:
Originally Posted by BoxMann
The car was aligned 30 days, 400 miles ago, by a top notch Porsche indy shop.
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Check the torque on your lug nuts.
__________________
2003 Boxster S
| 987 Air Box | K&N Air Filter | 76mm Intake Pipe| 996 76mm TB | 997 Distribution T | Secondary Cat Delete Pipes | Borla Muffler | NHP 200 Cell Exhaust Headers |
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06-12-2019, 08:19 AM
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#9
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Registered User
Join Date: Nov 2018
Location: NY Suburbs
Posts: 339
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Quote:
Originally Posted by KRAM36
Check the torque on your lug nuts.
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The shop uses a torque wrench on all the lug nuts, not a pneumatic impact wrench. This is a top notch Porsche shop, not Midas Muffler.
__________________
2004 Boxster S, 6 spd, Triple Black
1986 944 Turbo (sold in 1988)
Since then, a 300ZX, a few BMW 3 Series, a few VW's
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06-12-2019, 08:42 AM
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#10
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Need For Speed
Join Date: Feb 2013
Location: Funville
Posts: 2,112
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Quote:
Originally Posted by BoxMann
The shop uses a torque wrench on all the lug nuts, not a pneumatic impact wrench. This is a top notch Porsche shop, not Midas Muffler.
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I don't care what shop puts the lug nuts on my car after a tire change, I always come home and loosen the lug nuts and torque them down myself.
__________________
2003 Boxster S
| 987 Air Box | K&N Air Filter | 76mm Intake Pipe| 996 76mm TB | 997 Distribution T | Secondary Cat Delete Pipes | Borla Muffler | NHP 200 Cell Exhaust Headers |
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06-12-2019, 09:15 AM
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#11
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Registered User
Join Date: Jan 2017
Location: Edmonton,Alberta
Posts: 288
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I get a shimmy on the way to work in a few places. Its the paving on the freeway. I don't feel it when I drive my Jeep or Mazda.
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'58 356A coupe, just a driver
'00 Boxster S fair weather - daily driver
'11 Jeep Grand Cherokee Limited - winter daily driver
'92 F250 - junk hauler; previous Porsches '95 993;'08 Cayman S;'70 911E
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06-12-2019, 09:16 AM
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#12
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Who's askin'?
Join Date: Mar 2018
Location: Utah
Posts: 2,446
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Quote:
Originally Posted by BoxMann
I understand that those worn parts could cause a shimmy, but why would it happen intermittently? Wouldn't it happen consistently? And the shop (and PPI) inspected all of that and said everything looks good. And the car was aligned very recently. Those problems would have shown up on an alignment.
And it occurs on different roads.
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Intermittent is certainly plausible. As a part wears, particularly parts that affect steering / alignment, they will respond unpredictably to any input which changes the balance of the car: throttle input, braking, steering input, camber in the road, bumps, etc etc. Intermittent is certainly plausible.
And to your comment below:
Quote:
Originally Posted by BoxMann
.....This is a top notch Porsche shop, not Midas Muffler.
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I'd wonder how "Top Notch" they can really be, if they sent you on down the road with an "intermittent shimmy" that they can't diagnose? 
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06-12-2019, 09:31 AM
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#13
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1997 Tip, 2018 Macan
Join Date: Aug 2015
Location: Upland, CA
Posts: 1,338
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You should always re-check the lugs/torque after +/-500 miles. Most manuals will note this for every make/model vehicles.
Quote:
Originally Posted by KRAM36
I don't care what shop puts the lug nuts on my car after a tire change, I always come home and loosen the lug nuts and torque them down myself.
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06-12-2019, 10:00 AM
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#14
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Need For Speed
Join Date: Feb 2013
Location: Funville
Posts: 2,112
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Quote:
Originally Posted by rexcramer
You should always re-check the lugs/torque after +/-500 miles. Most manuals will note this for every make/model vehicles.
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I have not done it that way, makes sense, but I come home loosen the lugs and torque them and take the car for a around a 30 to 45 min drive and check the torque when I get home.
I'll check them again as it's been around 500 miles since I got my summer tires put on.
__________________
2003 Boxster S
| 987 Air Box | K&N Air Filter | 76mm Intake Pipe| 996 76mm TB | 997 Distribution T | Secondary Cat Delete Pipes | Borla Muffler | NHP 200 Cell Exhaust Headers |
Last edited by KRAM36; 06-12-2019 at 03:45 PM.
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06-12-2019, 10:09 AM
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#15
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Registered User
Join Date: Jan 2014
Location: New Jersey
Posts: 1,631
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Quote:
Originally Posted by BoxMann
Wouldn't a Roadforce balancer detect a wheel that's not true? And also, if that were the problem, why would it happen intermittently?
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I don't know how a road force balancer works, so I can't say. I've had tires road force balanced and been told I had a bent wheel when the bend was clearly visible, but have never been told that a wheel that looked straight and true had slight bends. It's been my experience over 16 years with my Boxster that these cars are very sensitive when it comes to steering wheel shimmy. The amount of gas in the tank, tire pressure, tread pattern and road surface all can make the shimmy intermittent in my experience. When I had all 4 of my wheels trued and refinished the car became the best it's ever been in 80,000 miles of driving it.
__________________
Current: 2022 718 Cayman GT4, PDK bone stock (the dark side).
Former: 2003 S, 3.6 LN Nickies, ARP rod bolts, under-drive pulley, Fabspeed sport headers, Softronic tune, 987 airbox 987 motor mount, Function-First Sport motor mount insert, Ben's short shifter, Nine8Six projector headlights & center caps, ROW M030, stainless flexible brake lines, B-K rollbar extension & fire extinguisher mount, hardtop
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06-14-2019, 06:41 AM
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#16
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Registered User
Join Date: May 2015
Location: uk
Posts: 36
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Why am I thinking of Tina Turner while reading this thread!
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