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Widening a track on vintage 911

I have a 1974 911 and would like to widen the track. The thing is that I want to know the max without interference or body modification(s). Can someone advise me as to what my limits are on both the front and rear tracks? Presently, it is a coupe with narrow body. Thanks in advance for your time and advice.

Old 11-28-2018, 06:39 AM
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A 17x8 wheel with a 30.4mm offset will fit up front, so I'm going to assume that it should fit the rear also. That should get you roughly another 2" in total track width from outside edge to outside edge.
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Old 11-28-2018, 06:54 AM
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Originally Posted by Spumato View Post
I have a 1974 911 and would like to widen the track. The thing is that I want to know the max without interference or body modification(s). Can someone advise me as to what my limits are on both the front and rear tracks? Presently, it is a coupe with narrow body. Thanks in advance for your time and advice.
It depends primarily on the width and o/s of the wheel/tire assembly, secondarily on the suspension sspec which includes ride height, alignment & t-bars.

For a stock '74 at stock ride height and mostly stock alignment, you can use ~3.5" of tire front space for a stock body(non Carrera, non turbo) rear will be similar.

In front and back that means a 7ET23.3 Fuchs w/ 205/55 tires. 15 will be shorter than 16 and so have a bit more room to play w/

if you go to custom wheels rather than Fuchs it opens up more possibilities, 8 ET25 -30 could be fitted, but tires will ultimately determine what works.
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Old 11-28-2018, 07:08 AM
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some body variance side to side

ON a bone stock 74 coupe, no accidents, with original, stock 6 inch Fuchs, a 205/60-15 Pirelli, I have some tire rubbing on the left rear fender up about 2 inches from the arch. Alignment set to stock specs. right side, one finger width clearance.

The limiting factor is the fender. If you dial in a couple of degrees of negative camber, you might be able to go a bit wider with the tires, or add a very small spacer

good luck,
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Old 11-28-2018, 07:10 AM
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my '76 came to me with 205/60-15 and 215/60-15's on 6 & 7 x 15 fuchs. car was lowered and fit was tight but all good.

tore it down and rebuilt it as a long hood, lowered it a bit more and currently run 205/55-15's all around. fit and performance are both very good. i like the 55's much better than the 60's. i tried some 50 series RE71's, but they were simply too short as i drive my car a lot, too low and the highway gearing sucked...
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Old 11-28-2018, 10:31 AM
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camber settings also affect wheel/tire fitment & track width, 30' of extra neg camber provides ~4mm of lip clearance while at the same time widening track by 4mm/side w/ the same wheels and tires

5.5" ET42 wheels will have a wider track than 6" ET36 wheels which will have a wider track than 7" ET23.3 wheels
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Old 11-28-2018, 01:53 PM
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And you want to do this why?

Widening the track has the effect of softening the spring rate, which is kind of an offset for hoped for improvement, so you would want larger torsion bars to go with the extra track. Even larger bars will reduce tire travel, which means a wider tire which is close to the fender (in the rear)should have less tendency to move up under cornering or bumps and burn the paint, which it can do even though there is no rubbing at normal ride height.

I assume you have rolled the front and rear fender lips so you can get a bit more tire under there.

But why the focus on the track width instead of seeing what the widest rubber you can run without a lot of changes might be?

Old 11-29-2018, 10:46 PM
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