Tuesday, 13 November 2012

Porsche 911T Project - Fuch off (or Wheels and Tyres)

The car arrived from Florida on what looked like a set of 15" diameter Fuchs (or 'Fox' in German) wheels in the classic early 911 two tone style. What was even better was that they were a nice wide rim that filled out the 2.7RS-style wheel arches - 7" wide at the front and 8" at the back. As an(other) aside, the RS was the first Porsche to be sold with different sized front and rear wheels, 6" and 7" in that case, although I remember them in the 80's racing on 7s and 8s. 

Sadly, a closer examination revealed that they might be all they first seemed; the finish was suspiciously shiny (not a factory style as far as I know), and the tell-tale edges of the 'spokes' were not smooth. Pulling them off revealed the truth, not only did the casting marks show they were US copies, but they each weighed a tonne! Unlike most alloy wheels, the Fuchs used on Porsches are forged, not cast. This produces a regular grain in the metal, giving material that is very strong for its weight. That's why Porsche are able to use their standard production rims in high stress competition applications - even rallying, and why the Fuchs are amongst the lightest wheels for their size. 

Now when it comes to wheels and tyres, lighter is better. I'm no chassis engineer, but even I can see that springs and dampers are going to find it difficult to control a big heavy object flapping around at the end of the suspension, and that less weight will give them an easier time. All things being equal, reducing this unsprung mass gives ride, traction and handling benefits - and for a driver the car just feels nicer to drive.  I can remember a back to back session I enjoyed with Caterham a few years ago, comparing one car on fashionable larger rims and low profile tyres with one on the traditional 13"s. All who tried it preferred the car on the smaller (and lighter) wheels. However, cosmetics are important to all of us, and a set of skinny wheels would look lost in the RS arches on the car, so I started to look into the possibility of replacing the replicas with the real thing.

It rapidly became clear that for the last few years the smart money has been investing in gold, African diamond mines and old Porsche bits.  Some of the prices for genuine Fuchs wheels, especially in the rarer and wider sizes made my eyes water - had I decided to go for a 11" wide RSR wheel I'd have needed to find several thousand pounds - for each one.

Hmmm, these or Rio Tinto Zinc shares?
Eventually, ebay turned up a suitable set in the US. I made an offer, and the money I saved over the advertised 'Buy-it-now' price paid for shipping to the UK, and the customs gouge. On arrival they proved to be a good buy, little used, and not suffering from 'refurbishment', which often involves taking metal off the rims. They're a later date from 1983 (the build date is stamped on the back of real Fuchs wheels) and the centres are all-black, but they were very noticeably lighter that the reps currently on the car. 
Looking good at a trial fit

It didn't take long for me to fit them onto the car - a quick mock-up showed the all-black rims worked well with the various black bits now appearing - and a spin around the block revealed that a noticeable edge had been taken off the low speed ride, and the steering had lightened up a bit.

A quick word on tyres. Finding suitable fat 15" rubber for an old 911 hotrod is not getting any easier - blame the increasing use of gigantic wheels on anything more sporty than a bog-standard shopping hatchback. It is possible to get sticky track-day tyres, but finding something that is period sympathetic is more difficult. The original RS used 185/70 and 215/60 on its 6" and 7" rims, while the early turbo's fitted with the same 8" and 9" rims I'm using had 205/50 and 225/50 - sizes no longer available from the same manufacturer - not 'V' rated anyway. 
 Ur-Fuchs fitted!

After much discussion with Tuthills, we decided to go up a size, and I've had 205/60s and 225/60s fitted, both ContiPremiumContacts from Continental. They were designed for heavy saloons, not the 400kg front of a 911, so we'll see how we do. At least I'm able to take advantage of the 40 years development in tyres that have taken place since the car was built. 
The Fuchs Reps went on ebay......

So far, I'm pleased to report, the limitations of the car's speed is still the driver.

That's pretty much it for the cosmetics - interior next!


Porsche Dealer said...

One of the most proficient Porsche models on the racetrack is the 911 GT3. It is designed specifically after the GT3 RSR race cars that Porsche uses in motorsports worldwide and is built to handle fast corners with ease.

frankee seo said...
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