What's new
Porsche 911 UK Enthusiasts Online Community Discussion Forum GB

Welcome to the @Porsche911UK website. Register a free account today to become a member! Sign up is quick and easy, then you can view, participate in topics and posts across the site that covers all things Porsche.

Already registered and looking to recovery your account, select 'login in' and then the 'forget your password' option.

An Independent Porsche Specialist providing Low Mileage High Specification Porsche for sale

tyre drag

M

marino

Silverstone
Joined
29 Jan 2012
Messages
134
Hi, when I turn the steering full lock the front tyres seem to drag [when parking] pzero n2, this did not happen with the previous n1 p zero. Can anyone tell me why. Carrera S 2007 thanks.
 
It's rear wheel drive and the laws of physics.the inner wheel is travelling the same as the outer. Impossible to do as the outer wheel has got to travel further than the inner. All wheel drive eliminates this with the diff.
 
Just new tyre tread gripping and "jumping" (it means your old tyres were either slippier or the weather was!).

Nothing to do with RWD (in fact it would happen on a FWD and AWD with the same geometry and width of tyres etc).

Therefore upgrading to a C4 ain't going to help.


This "scrabbling" is normal on lock due to the greatest difference in turning radii between inner and out wheels and the camber induced.

Exacerbated by wide tyres and cold tyres.

If we are talking laws of physics, simply familiarise yourself with Ackerman Angles:

488px-Ackermann_turning.svg.png


The steering system does implement an Ackerman compensation, but limitations due to complexity and robustness and catering for straight line feel and linearity etc, this is not perfect.

Even this little Lego version implements an Ackerman compensation geometry:

http://www.sheepo.es/2011/05/porsche-911-997-turbo-cabriolet-pdk_04.html

The above shows the idealised (zero contact pacth width) Ackerman compensation linkage.

There are many mechanical reasons why this cannot be implemented in reality.

The wide tyres is the most fundamental (as the inner and outer shoulder require different Ackerman compensation angles).

The jumping is when this differential force overcomes the tyres differential grip (across tread - greater force the greater the width or turning angle) - which occurs more likely under cold (hard) tyre conditions.
 
Someone recently told me that the tyres go `a bit plastic` at these low temperatures.
My Vito does the same when I reverse off the drive on hard lock. Normal, especially with wide tyres.
 
GT4- that's physics- like under steer, the forward force is more than than lateral grip :?:
 
chaser said:
Someone recently told me that the tyres go `a bit plastic` at these low temperatures.
My Vito does the same when I reverse off the drive on hard lock. Normal, especially with wide tyres.
Click to expand...

Yes and no to your source.

In the relative material comparison (soft) rubber vs (hard) plastic, yes

In the Latin sense, no. (as plastic's pliability definition would be the perfect description of rubber!).

Assuming the former, as I said, coldness exacerbates the effect as the hard rubber can't gradually give, but alternately digs in and then lets go (causing the mini jumps).
 
Alfaian said:
GT4- that's physics- like under steer, the forward force is more than than lateral grip :?:
Click to expand...

Everything is physics.
 
Thanks, for the lesson in physics,i take it that its normal for these mini jumps with the new tyres.Thinking back the old tyres were well worn ,down to the legal limit. [getting my money worth] Thanks again
 
Get a few miles on them and see how you go on, the wider tyres will increase the Ackermann principle.
 
Would it make any different if the wheels were 8.5j instead of 8j, but having the same 235/35/19 tyres.
 
At a good guess.....No.
 
Worse (the tyre will be stretched more taught for the same pressure)
 
You must log in or register to reply here.

Similar threads

G
992 2wd traction / tyres
Replies
11
Views
839
911UK
911UK
5
Pirelli tyre problem
Replies
8
Views
808
Wh1t3Kn1ght
W
Maxie
Back in the game.....second attempt!
2 3
Replies
38
Views
3K
911UK
911UK
T
991.2. Whats it worth in todays market
Replies
10
Views
1K
T8
T8
U
Cannot find front tyres for months now, any tips? 225/40/18
2
Replies
15
Views
2K
Simon W
S
C
Help: Bizarre deadlock situation
Replies
6
Views
1K
jonttt
jonttt
J
  • Locked
Sold 997.1 C4S Manual Convertible 2006 53k Miles [Sold]
Replies
3
Views
701
jcw749
J
Independent Porsche Specialist

Latest posts

New Threads

Porsche Model Range

Porsche 911

Porsche 992: 2018- Porsche 992: 2018- Porsche 991: 2011-2019 Porsche 991: 2011-2019 Porsche 997: 2004-2012 Porsche 997: 2004-2012 Porsche 996: 1997-2005 Porsche 996: 1997-2005 Porsche 993: 1993-1998 Porsche 993: 1993-1998 Porsche 964: 1989-1993 Porsche 964: 1989-1993 Porsche Carrera 3.2: 1983-1989 Porsche Carrera 3.2: 1983-1989 Porsche Carrera SC: 1977-1983 Porsche Carrera SC: 1977-1983 Porsche 930 Turbo: 1975-1989 Porsche 930 Turbo: 1975-1989 Porsche Early 911: 1964-1977 Porsche Early 911: 1964-1977

Porsche Hypercars

Porsche 918 Spyder Porsche 918 Spyder Porsche Carrera GT Porsche Carrera GT Porsche GT1 Porsche GT1 Porsche 959 Porsche 959

Other Current Porsche Model

Porsche Taycan : (2019-0%) Porsche Taycan : (2019-0%) Porsche Macan : 2013- Porsche Macan : 2013- Porsche Panamera : 2009- Porsche Panamera : 2009- Porsche Cayman: 2005- Porsche Cayman: 2005- Porsche Cayenne: 2003- Porsche Cayenne: 2003- Porsche Boxster: 1997- Porsche Boxster: 1997-

Porsche Legacy Models

Porsche 928 Porsche 928 Porsche 968 Porsche 968 Porsche 944 Porsche 944 Porsche 924 Porsche 924 Porsche 914 Porsche 914 Porsche 912 Porsche 912 Porsche 904 Porsche 904 Porsche 550 Porsche 550 Porsche 356 Speedster Porsche 356 Speedster Porsche 356 Porsche 356

Forum statistics

Threads
124,609
Messages
1,442,049
Members
49,041
Latest member
Stoker

porsche insurance porsche parts porsche sales porsche car sales porsche for sale
porsche classic sales porsche tuning porsche sold porsche specialist porsche engine rebuilds porsche driver training porsche car sales porsche exhausts

Community platform by XenForo® © 2010-2024 XenForo Ltd. XenForo theme by xenfocus

www.911uk.com @Porsche911UK THE DEFINITIVE PORSCHE FORUM Copyright © 911UK 2002-2024 All rights reserved.

911uk.com is not associated and is wholly independent of Porsche Automobil Holdings SE, Dr. Ing.h.c.F.Porsche AG, Porsche Cars GB, its subsidiaries and offical Porsche centres. Any word, phrase or graphic that in any way resembles anything to do with the Porsche name or organisation are registered trademarks of Porsche Automobil Holdings SE and Dr. Ing.h.c.F. Porsche AG.

Back
Top