964 Register visit to centergravity: any RS's owners intereestd?

[Alexander_Drobik]

The 964 Register will be visiting wheel alignment specialists - centergravity on Saturday July 7th.

Centergravity (http://www.centergravity.co.uk) in Hinkley (outside Nuneaton) has invited the Register to see how you setup a 964's suspension, wheel alignment, corner weighting, etc including a practical demonstration with a donor car.

I have a few places left so if anyone would like to join the visit please let me know in response to this post, else email: registersecretary964@mac.com.

Mel - thanks for allowing me to post this!

 

[Melv]

Alex -just ask em why they insist on set up BEFORE new tyre replacement whereas everybody else wants the new tyres on BEFORE set-up.....

 

[Alexander_Drobik]

Mel - will do. I have heard it both ways - have new and have slightly worn. No idea what is best!

 

[burrow01]

Hi,

When Chris did the alignment on my 993 he was very interested in the condition of the current tyres as an indicator of any existing problems

Cheers

Pete

 

[Dave Wilkinson]

I don't know about anyone else's view but I think I would be a bit worried about this. Surely it should be assumed that the geometry is WRONG and should be setup from scratch to be correct. If he is relying on the stae of the old tyres to judge the existing setup he must be using it to decide what needs to be changed rather than setting it all up from scratch. I might understand this if it were a time saving exercise - but I'm not convinced it would fill me with confidence.

IIRC when JZ Machtech do an alignment they will measure the existing set up and, if it needs adjustment, they will start from scratch. I really can't see the value of looking at the existing tyres. Tell me if I'm wrong.

Regards

Dave

 

[Alexander_Drobik]

I spoke with Chris Franklin of centergravity on this. He responded with a very detailed account of the issue - which I summarise below. The upshot is they don't force using old tyres and if you want to understand in detail what takes place here"¦..Pls come ALONG! Anyway, Chris said:

a) Geometry set is on the front and rear wheel hubs, so technically the wheel/tyre combination is secondary.

b) With new geometry settings, these can affect the car feel until the tyre has worn (scrubbed) to the new geometry profile. One of the reasons a chassis/suspension tuner provides a warranty is to address any minor issues after the scrub-in period. We provide a 1,000mile warranty for such cases.

c) The key is that I get to see the old tyres and use the evidence collected to corroborate the feedback (on any handling problems) from the driver and geometry data captured by the equipment. From the tyres I can deduce;
· Over toe-in
· Over toe-out
· Issues with toe-out in turns
· Unequal cambers across an axle
· Net braking style of driver
· Net acceleration style of driver
· The optimum camber for the driver
· Correct use of tyre pressures
· Specific handling problems due to tread depth or rubber hardness

d) It is true that new tyres would give the correct ride-height (3-4mm difference between a new tyre and part worn), however even new tyres front to rear have different tread depths from new.

e) Not everybody has handling problems that require such fine investigation, in which case they may fit new tyres and the get a geometry check. Mostly us Porsche type are absolute perfectionists and looking and "˜feeling' the old tyres gives me the best chance to give the best, most accurate service possible.