What is 'level'?

[aijf912]

My first post so sorry if I'm covering old ground, but I can't find quite what I'm curious about anywhere when I search.

Our 1969 912 has been tucked away for about 15 years while we've been busy having kids and renovating houses (neither complete). Now the kids have got me to get it out and running to take them to their 5th and 6th form proms. I've fallen in love again and have been tinkering with it non-stop since.

The latest job is sorting out the wheels (we have on 5.5Jx15 and three 6Jx15s ?!), tyres (we have 195/65R15 on the back and 185/65R15 on the front and I want 185/70R15 all round) and ride height. Attached is the before shot, where I think it looks too low and a bit nose up. It measured 138mm torsion bar to hub at the front (30mm too low) and -32mm at the back (44mm too low). I have set the rear control arms to 16 degrees (wrt the door sills) and the front to 108mm. The result is the second photo. Too much of a nose-down stance (of course the same tyres all roud will help here)? I've been trawling through all the side views of 912s I can find. There isn't much consistency. Should the top of the door be level and the sills be pointing down a bit? I see a lot of people measure to the wheel arches but a small distortion in the bodywork could change these a lot. Is there a bit of the car that should be level when the suspension heights are 'correct'?

Any more thoughts other than set it how I like the look of it? BTW, I think I prefer the way it handles now. I'm no handling critic, but it seems a bit more lively and playful.

Cheers!

[aijf912]

Or, more concisely, if I put an inclinometer on the top of my 912 door (or sill) what should it read?

[Gary71]

Or, more concisely, if I put an inclinometer on the top of my 912 door (or sill) what should it read?

Traditionally (for a 911 anyway) -1 deg assuming the car is on level ground

Never quite managed that myself!

[Gary71]

I’d say rear looks good in your first pic and wind the front down to hit the angle and it will be about right

[aijf912]

Or, more concisely, if I put an inclinometer on the top of my 912 door (or sill) what should it read?

Traditionally (for a 911 anyway) -1 deg assuming the car is on level ground

Never quite managed that myself!

Thanks - is that the top of the door or sill?

[aijf912]

I’d say rear looks good in your first pic and wind the front down to hit the angle and it will be about right

It was nearly two inches lower than the original spec. In terms of sump clearance, I found that a bit scary on the roads around here! (Staffordshire Moorlands)

[Lightweight_911]

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I would wait until you've got the new tyres on (& preferably a full tank of petrol) before finalising your ride height settings.

IMO the 2nd picture looks too high all round - as Gary said the first picture looks better, just needs the front lowering to give ~ 1deg rake along the sill.

- as an example - here's my '71 911T with more or less std ride height (I lowered the front a little bit more after this was taken) ...

[911hillclimber]

I have always thought Andy's 911 was spot-on, mine is a little lower (approx 10mm).

You need a good ride height to allow you to drive over speed bumps and awkward driveways without having to worry about impacts.

My 911 has the front lower suspension arms set level to the ground.
The rear is raked up by 1 degree measured along the door sill and this is set by adjusting the rear suspension.
All the tweaking should be done on a good level floor, do not assume your garage floor if flat. Mine is 15mm down in one corner.

Sometimes it is best to take it to a well equipped independent Porsche specialist esp if you have one piece rear spring arms, but a satisfying job to do if you can DIY the car.

[aijf912]

Thanks for all this. Andy, do you know what your torsion bar to wheel centre vertical distance is? In my first image mine was -32mm (44 mm lower than what the workshop manual says it should be). In the photo below you can see the torsion bar was well below the wheel centre. I've now had a bit more of a drive and gone back to my favourite bit of levelish concrete to take the other photo below. The rear torsion bar is now ~12mm higher than the manual says and the door sill is ~-1deg wrt a line drawn between the front and rear wheel centres. It's driving very nicely and I'm going to leave it until I get the matching deep six and new tyres before doing anything else, but it looks like I need to raise the torsion bar by about 1 degree (or the 50' or 1deg40' possible). I'm keen to know what other torsion bar to wheel centre distances others are running though.

[Lightweight_911]

Andy, do you know what your torsion bar to wheel centre vertical distance is?

Difficult to measure accurately on mine as I have the wide anodised aluminium sill trims which mask the torsion bar covers & my wheels don't have centre caps ... but I'd say that measurement is ~ 17-18 mm


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[911hillclimber]

Interesting!
Just measured my 73T and the difference is 45mm, wheel centre 300mm and torsion bar cover centre 245mm from the floor.

[Lightweight_911]

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I'll attempt to take a more accurate measurement tomorrow but if I was keeping the car I'd probably lower it ~ an inch which would make it more or less the same as yours Graham ...

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[210bhp]

Where is the stick man when you need him?

Regards
Mike

Apologies to the original poster who will probably not understand this comment.

[911hillclimber]

I would not go lower on my car today, but it was lower when hillclimbing it due to 50 profile tyres used.

Since my DIY set-up about 8 years ago it is great and rides far better on large section tyres.

Bob once set it to his 'hillclimb spec' but the car was impossible on the general road, a compromise was needed and found.

[Lightweight_911]

Where is the stick man when you need him?

Not seen the famous 'stick' being wielded by its keeper for many years !

Now seems to be confined to DDK folklore ...


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