12-29-2011, 10:33 PM
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#1
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Registered User
Join Date: Jul 2011
Location: so cali
Posts: 302
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tires skipping during hard acceleration with psm off
Just curious if this is normal.
I purchased my car about 6 months ago and i have never turned off psm before. It was a quite foggy earlier and the ground was a little moist. I wanted to see what type of traction and how hard I can accelerate before the rear tires break loose. I recently purchased some hankook v12's about 1,000 miles ago.
In all my previous cars that i've tried this one, when you lose traction it just feels like you're not moving and the rear tires spin with traction control off and eventually it gets grip and you start moving.
When I tried this earlier, my rear end skipped, feels like going over a really bumpy road, except in my case, the road was smooth.
Is this normal and is it because my tires are fairly new? thoughts?
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12-29-2011, 11:05 PM
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#2
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Registered User
Join Date: Aug 2011
Location: Malta
Posts: 144
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I get the same feeling when PSM is on.
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12-29-2011, 11:07 PM
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#3
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Registered User
Join Date: Jul 2011
Location: so cali
Posts: 302
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No, when PSM is on, the power to the rear wheels get cut off not allowing you to spin the wheels or just slightly.
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12-30-2011, 02:04 AM
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#4
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Registered User
Join Date: Dec 2007
Location: Seattle
Posts: 735
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What you are experiencing is called axle tramp. It is common on cars with independent suspension.
A Boxster is not a drag racing car and the suspension is not configured for tire spinning starts.
__________________
2000S Ocean Blue Metallic- 116K
3X Water Pump, Clear side markers, Crios Mod, Front engine mount, Flywheel, clutch, RMS, AOS, MAF, serpentine belt, power brake vacuum line, battery, 2X CV boots, Fuel filter, Oil filler tube, 3X ignition switch, 90K service, gas cap
Last edited by Spinnaker; 12-30-2011 at 02:10 AM.
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12-30-2011, 02:07 AM
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#5
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Registered User
Join Date: Jul 2011
Location: so cali
Posts: 302
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Thanks for the explanation. Perhaps i wasn't clear in my original post, the reason for me trying this was just to see how much traction I have before the tires breaking loose. I believe it's good practice to know your cars limitations/capabilities, especially if you change brand tires.
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12-30-2011, 02:29 AM
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#6
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Registered User
Join Date: Dec 2007
Location: Seattle
Posts: 735
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Now that I re-read your original post, I understand what you were doing. I did the same thing when I first got my Boxster, wanted to see how much traction the tires had when the road was wet so I could get a better feeling for the amount of grip to expect. Didn't want to get too tail happy by accident.
__________________
2000S Ocean Blue Metallic- 116K
3X Water Pump, Clear side markers, Crios Mod, Front engine mount, Flywheel, clutch, RMS, AOS, MAF, serpentine belt, power brake vacuum line, battery, 2X CV boots, Fuel filter, Oil filler tube, 3X ignition switch, 90K service, gas cap
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12-30-2011, 05:38 AM
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#7
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Registered User
Join Date: Aug 2007
Location: New Jersey
Posts: 691
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I get wheel hop when I leave my neighborhood on occasion.
I have to turn right and accelerate rapidly up a steep hill. It's noticeable when there is bad traction if the road is wet or sandy, etc. But, if you modulate the throttle it's easy to prevent. That is the only spot that it happens, and it won't happen if you're even a little aware of the potential.
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SOLD - 2002 Boxster S - PSM, Litronics, De-ambered, Bird Bike Rack, Hardtop, RMS leak...
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12-30-2011, 06:35 AM
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#8
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Registered User
Join Date: Nov 2010
Location: Philly
Posts: 594
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This happens to me too. Another thing. Is the Boxster's traction control really that effective?
With my traction control on, I still spin out the tires when accelerating in cold weather(because summer tires), and in parking garages(because smooth cement). I barely hit the gas and the wheels spin and my traction control light blinks rapidly.
Is the traction control supposed to allow some wheel spin?
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12-30-2011, 08:13 AM
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#10
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Porscheectomy
Join Date: Mar 2006
Location: Seattle Area
Posts: 3,011
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Quote:
Originally Posted by Spinnaker
What you are experiencing is called axle tramp. It is common on cars with independent suspension.
A Boxster is not a drag racing car and the suspension is not configured for tire spinning starts.
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+1 and it's very hard on your drivetrain. The impact of the little jumps in traction can break joints and gears. It's very common on Porsches in general from what I understand.
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12-30-2011, 09:20 AM
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#11
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Certified Boxster Addict
Join Date: Nov 2010
Location: Los Angeles
Posts: 7,669
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Its also called axle hop or wheel hop and yes, its normal on our cars (and many, many other cars).
It happens because the suspension allows the wheel to move up as its reaching maximum traction (the torgue winds up the suspension) rather than keeping the wheel firmly on the ground and having the tire spin. The net result is that the tire "hops" up and down as it grips, loses grip, and grips again.
Blue2000s is correct that this is VERY hard on the transaxle and CV joints. Don't get me wrong, the car is built to take some abuse but damage can occur so you're best bet is to minimize axle hop to avoid any problems.
Unless you are willing to do some suspension mods (usually starting with at least new shocks), then you'll have to live with it. Drag racers go so far as to install special "torque arms" or other suspension mod's to eliminate it.
__________________
1999 996 C2 - sold - bought back - sold for more
1997 Spec Boxster BSR #254
1979 911 SC
POC Licensed DE/TT Instructor
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12-30-2011, 10:36 AM
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#12
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Registered User
Join Date: Nov 2009
Location: Winnipeg MB
Posts: 2,486
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I had bad wheel hop until I changed my front motor mount. Now I get none regardless of how hard I launch it
__________________
'99 black 986
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12-30-2011, 03:12 PM
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#13
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Registered User
Join Date: Aug 2009
Posts: 1,466
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Quote:
Originally Posted by Mark_T
I had bad wheel hop until I changed my front motor mount. Now I get none regardless of how hard I launch it
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Hey thank you, this is a good confirmation of something I was starting to feel the last several week ends I had the car out in the morning when it was cold.
__________________
2003 Black 986. modified for Advanced level HPDE and open track days.
* 3.6L LN block, 06 heads, Carrillo H rods, IDP with 987 intake, Oil mods, LN IMS. * Spec II Clutch, 3.2L S Spec P-P FW. * D2 shocks, GT3 arms & and links, Spacers front and rear * Weight reduced, No carpet, AC deleted, Remote PS pump, PS pump deleted. Recaro Pole position seats, Brey crouse ext. 5 point harness, NHP sport exhaust
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12-30-2011, 03:17 PM
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#14
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Track rat
Join Date: Nov 2006
Location: Southern ID
Posts: 3,701
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Quote:
Originally Posted by blue2000s
+1 and it's very hard on your drivetrain. The impact of the little jumps in traction can break joints and gears. It's very common on Porsches in general from what I understand.
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Yes. Wheel hop/axle tramp are one of the best ways to murder your transmission (ask me how I know . A gentle right foot that can ride that fine line between max acceleration and spinning the inside wheel is to be found on a very skilled driver indeed.
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2009 Cayman 2.9L PDK (with a few tweaks)
PCA-GPX Chief Driving Instructor-Ret.
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