Front end alignment

[SportoEvans]

Hi all-

I really need to get my front correctly aligned - I guess factory settings for camber, caster & toe.

From 115KPH up I get significant front vibration, although no steering wheel shaking. My got my wheels recently balanced.

I don't want to use one of the usual retail wheel alignment shops but a shop/person that offers this specific service and specialises in early Porsches (or at least classic cars).

In Melbourne - who are people using/who is the best/ who can be recommended?

many thanks

[marcus_cottrill]

You cant go past Carl Jones ... He's the expert ; carl888 on this forum.

[Terminator]

Hi all-

I really need to get my front correctly aligned - I guess factory settings for camber, caster & toe.

From 115KPH up I get significant front vibration, although no steering wheel shaking. My got my wheels recently balanced.

I don't want to use one of the usual retail wheel alignment shops but a shop/person that offers this specific service and specialises in early Porsches (or at least classic cars).

In Melbourne - who are people using/who is the best/ who can be recommended?

many thanks

What are you doing driving at that speed

[Merv]

Ha ha. I used stock settings as well via Fulcrum in QLD

[SportoEvans]

Thanks Markus. I will send him a private message to get more info.

[griffiths_r]

+1 on carl

[Merv]

An earlier thread https://www.typ901.org/forum/forum/t...nment-settings

[carl888]

Hi all-

I really need to get my front correctly aligned - I guess factory settings for camber, caster & toe.

From 115KPH up I get significant front vibration, although no steering wheel shaking. My got my wheels recently balanced.

I don't want to use one of the usual retail wheel alignment shops but a shop/person that offers this specific service and specialises in early Porsches (or at least classic cars).

In Melbourne - who are people using/who is the best/ who can be recommended?

many thanks

Some pertinent information:

1. All 911s and 912 have adjustable front AND rear suspension settings. Both must be checked, it's a service item.

You cannot adjust caster and camber on the front of early 911s. I am doing this from memory but I think 1969 is the model year that introduced this extra adjustment on the front. Since production began in 1963, the rear is adjustable for toe and camber.

The factory settings take into account the extra bands of rayon present in tyres used in period which are now lacking on modern offerings. I've found a small degree of front negative camber with stock toe and caster corrects for this using modern tyres if you are driving your car on the street.


2. There is no relationship between between alignment settings and vibration. An alignment will not fix your vibration. Your vibration is caused by:

- improper balancing.
- a front or rear tyre balanced but being out of round.
- bent and/or warped rim.
- wheel bearing clearances excessive.
- summation of unfavourable tolerances; run out in tyre, unbalanced brake disc, uncentered PCD, slack in steering rack, worn suspension bushes additive in their tolerances.
- something sinister in the drivetrain.
- dragging brake pads
- steering rack and tie rods worn (Front vibration only)

3. There is one possibility that affects cars with a short wheelbase and I have experienced this with two vehicles, a 1987 911 and a 1967 250 SL. As the freeway surfaces ages, small ripples appear in the tarmac, although this phenomenon is usually restricted to unmade roads, it occurs on sealed surfaces too, washboarding (Or corrugations)

http://www.lgam.info/washboarding

Usually amplified by worn suspension and in particular worn dampers, I have found that at 107 km/h I cannot totally eliminate it in the 911 (1987 Carrera) and this car has been prone to vibration on some sections of the Hume Highway since new. The key to diagnosing this problem is that it won't suffer vibration on all road surfaces at 107 km/h. It appears that the short wheelbase and the damping conspires to produce a vibration that can be felt through the car but not through the steering wheel.


4. Others can speak for me.


CJ.

[SportoEvans]

Thanks Carl-

A very interesting & comprehensive explanation.

My vibration issues have occurred since I:
(1) changed tyres (to Michelin XWX 185/70VR15) that were balanced when fitted;
(2) had the 4 new discs subsequently machined because they had either become warped or had high spots (because they were not "bedded -in" correctly causing pulsation under braking.

I haven't felt any pulsing under braking since machining so I guess the place to start is the get the wheels re-balanced.

Do you wheel balancing as part of your business? If not who is the best, you uses the best wheel balancing technology ?

cheers
mark

[klasikcis]

Hi Mark, while I am only a bush mechanic sounds weird that you had 4 brand new discs that needed machining within your first few thousand kms. Are they aftermarket or genuine? Secondly who supplied and fitted the new Michelin?

[carl888]

Do you wheel balancing as part of your business?

Yes.



If not who is the best,

Anyone that applies engineering principles and the basic laws of physics can perform it with a machine that's very accurately calibrated.




you uses the best wheel balancing technology?

Yes, however the technology is irrelevant, it's the interpretation of the data and variables applicable in my original reply that apply.



so I guess the place to start is the get the wheels re-balanced.

No. Check for run out, bearing, brake, damper, rack etc issues first whilst the wheels are fitted. You can do this at home. Just jack up each wheel and rotate by hand. Give the wheel a good axial and radial tug whilst you're there. Have an assistant lightly press the brake pedal whilst rotating the wheel too.

[SportoEvans]

Hi Neville,

All 4 disc's new from BWA Auto in Derrimut in 2014. Brembo with Porsche OEM part numbers.

They had done 1,300 miles when my mechanic machined them flat. He inspected them them and told me the surface was uneven maybe as they were new, the metal was "green" and sometimes after a year or so with little use, the surface matures or it could have been that the brakes were not bedded-in correctly (I think this is were microscopic parts of the brake pad is applied to the surface of the disc). I had not heard of the "green" metal maturity issue before maybe its an issue for new parts for older cars.


The Michelin's from Stuckey's in Brunswick. They also balanced them.

cheers

[SportoEvans]

Thanks Carl. What number can I call you on?

[carl888]

0434 768 308 All ways best to call between 5-6pm.