I remember reading an article about this but cant find it any where anyone seen it on the www?

germanlook forums tech articles
http://www.germanlook.net/html/tech/Tech12NarrowingIRSArms.php 
can i ask though... why?

Thanx mate would normally just jump in and do it but a bit of knowledge is good! 15x7 cookies under standard guards make for a tight workplace!

Yeah, agree with Damo... cookies usually go up no probs at all.

If they don't, check the stampings on the inside... cookies were available in a couple of different offsets

should comfortably fit 9s under a stock guard given the right offset -not being porsche specific so a 7" should be easy as... offset too low? any spacers? ditch them.

nah no spacers. ea rear brakes got about 50mm clearence to the spring plate and pretty tight to the lip on the 1303 guard with the 15x6 with a 195(read good fit) but the 7inch has a deep dish with the same back space just thought would be easy to take 30mm out of it and squeeze in a 225.

thicker rubber for beading like sides has or guard rolling could be far easier ways...
that or different style porka wheel with higher offsets available
just trying to give alternatives, its alot of work to fit such a small width thats all, tho with a 17x8 with a 235 on it i can see what you mean, offered up a stock guard for shits & giggles, stuck out 1-2"

yeah it is a lot of work but i am a welder so not a big drama just wana get it to look right as its my road car! not my race car.

A 225 size tyre on a 7 inch rim would be very baggy.
Around hard cornering you will find the rim will roll across the tyre, correct size for a 7 is a 205.
Hope this helps.

Cheers Col

6" are 35/36mm & 7" are 23mm, I have late type 3 brakes on the rear of my swingaxle '72 beetle & I found the same as Mac, 7" with 205 would not clear my standard guards.


Cheers
Brendan

Would narrowing the rear to get larger / wider wheels impact the handling negatively?

Yes.
Think of a drag car which has very narrow rear end to fit large wide slicks, they are very unstable when they get out of shape.

Cheers Col

I would think drag cars get out of shape due to the soft sidewalls and geometry/suspension settings (alignment and shocks) that are straight line focused.

I wish the Ghia had more options. I'm running it as a driver's school car and occasional daily driver / fun car. I really like the idea of 7" wide rear and 6" front Fuchs to fit over the 944 brakes I've got for it. Plus, there are some decent 16" tires out there for me to run.

correct me if im wrong but if the guards remain "filled" there will be no significant change of roll centre. Maybe applied loads will change slightly but the "basic" will be the same.! not talking about drag style tyres here we are taking about tyres that go round corners!

mactaylor,
That was my thinking. I'm not tucking the tires for the 'Johnny Drag-Strip' look, but allowing a 7" to 8" wide wheel to fit more 'comfortably' to maintain traction turning right and left.

Dependant on how wide you go and the offset, you may alter your track slightly as the centre of each tyre will move inwards. How this combined with the standard geometry will change the handing of the car I am not sure about.

As I didn't study mech engineering I am a little rusty but 2 options exist, excluding any affect on the suspension.
1. The edge of the tire will be further out from the centre of the car, therefore providing more stbaility
2. the centre of teh tire and hence track will be narrower, therefore reducing stability

Where is a car dynamics engineer when you need one!

Dorigtt

What are you running on the front and back of your Ghia?

Cheers

Newt

@BiX - I've been clicking my heels and no engineers have appeared so far. Your line of thinking does make sense though.

@Newt - Currently...car dolly. Planned...Fuchs alloys in either 16x6 - 16x7 front to rear stagger, or 16x7 - 16x8 front to rear stagger. The Fuchs all have pretty shallow - compared to later Porsche wheels - offsets which would push the wheel / tire combination outward. While being no big deal for the bolt-on-fender crowd, the Ghia requires sexual re-assignment surgery to make them work from all the reports I'm getting.

Mactaylor, I have had my IRS arms narrowed by 28mm each side. This is to run 8" wheels and 235's Mickey Thompson Street Slicks on my oval. Still had to go 2" widened guards. I now think I could of ran standard arms and fit a bigger tyre (245's)but not had my car as low for the tubbed look.

I can take a few pics of how it was done if you like.
Something to be wary about is i had to have all the bearing chases re machined due to warping because of the heat. I didn't weld them and it caught me out as they went out of round and when I went to re-assemble the bearings didn't fit. All corrected now, just a expensive hiccup!
Let me know,
T54

I had Blindchickenracing build a set of narrowed arms in order to fit the rear wheels under the rear fenders.

Wish me luck.

That's some pretty metal work.

Seems like a lot of work, I think if you narrow the rear track beetles produce more oversteer, tail happy type driving. But if you have much fatter tyres on the rear and cutters up the front the rear will want to push the front around a corner... So I think, you end up with an upset car

Go for it....good luck buddy. I don't think you'll notice any ill effects with the handling, just hope it all fits.

@ matberry - I'm sure it'll fit (whispering...get the plasma cutter. QUICK)

@ Aussie Dubbin - I think they weigh a bit less than the factory arms as well @ 14# I'll measure them once the old ones are off. Right now I'm working on fitting the 915 trans and cooling lines for the new engine.