Alignment advice needed for 87' 930.
 

SmileWavy

I just finished installing Elephant Racing rubber bushings front and rear on my 87'- 930.

The current alignment information is as follows:

FRONT SUSPENSION:
Trim height:
136.5 mm
Wheel arch 24.625 in
Camber: LF -1 deg.
RF -1.7 deg.

Swaybar: factory diameter and mounting.

REAR SUSPENSION:
Trim height:
38.1 mm
Wheel arch 25.25 in
Camber: LR -1.5 deg.
RR -2.7 deg.

Rake: 1.7 degrees

I know that I'm way off.... Here is a photo.

http://home.comcast.net/~3_3_Liter/b...202_4_2012.png


The car now sits level side to side and the ride height is pretty close to what it was before. The rear is 1/2" lower than before the spring plate bushing install. Maybe this is ok????

My goals:
1) Learn a bit about alignment and balancing prior to taking to the local pro.
2) Adjust the car close in my garage before taking it to the pro wrench.

My questions:
1) Does the left-rear fender look too low. I think it might rub under hard cornering.
2) The left-rear tire is further outboard than the right-rear. This car hasn't been hit so I'm confused as to why the tire is pushed out. This has always been the case.
3) I assume lowering the car adds negative camber? My previous tires were worn out on the inboard 3 inches of tread and the rest of the tire looked new. This thing had a ton of rear camber in it before the bushing refresh. Is that common that clapped out spring bushings add a ton of negative camber?
4) Best way to fix the left-rear outboard tire issue. Thinner wheel shim? Another option?
5) What are some common alignment specs for a 17" tire Porsche 930 that I might track two-(2) times per season? Plus some very sprited twisty streets as well
6) Is the front too tall based on the photo? It looks perfect to me... Based on the US/Euro specs it's too low. If the front looks good (just low of the Euro spec, then the rear is good as well. Lower than the Euro spec. But I think it's too low and will rub.
7) If I raise the rear then do I also raise the front??

All information is appreciated.
__________________

I can only answer a few Q's being as how I am not very mechanically familiar with the 911/930.

1) You're LR fender does look low. But your car is lowered and you are also likely running a larger diameter tire than stock which may give the illusion of such. That said, when the turbo kicks in, it looks like you may rub. These cars squat ALOT under boost.

2) I do not know for the 911/930 specifically, but I know the 944 has this kind of asymmetry as well. I have heard it is done this way to counter the weight of the driver. But also check your wheel offsets - flip the wheels left to right, drop it on the ground, and see if it looks the same. It can be corrected with unequal spacers, but make sure your studs are long enough and your lugnuts fully engage. I recommend some steel lugnuts for the track, that's me.

3) Lowering the car without realigning it, will add camber, yes. That can be corrected in alignment though.

5) Specifically I do not know. Generally though, since you drive it on the track too, you may want to run a more aggressive alignment setup than stock. I do not know what is stock, and don't have any recommended settings for you, sorry!

As for aligning the car in your garage, a car can only be aligned correctly when the suspension is compressed as it would laying on the ground. If you have a lift this is fairly easy. With jackstands it can be difficult. Just when you let it down on whatever (solid cinderblocks maybe?) make sure handbrake is engaged, car in gear, etc. And as you can imagine, it may be hard adjusting stuff with not much room under the car.

Hope that helps!

Car looks great, btw! Those wheels and Fuchs are my top favorites on a pre-89 911!

From the photo it does look too low, measure from top/center of fender lip to the ground front and back to get a reference point

If is possible to align at home but it will take plenty of patience.

You need scales to corner balance it, if you can borrow it, that would be nice.

Your car is definitely too low ... you should be able to slip your fingers up to the knuckles at the least in the rear fenders and a whole hand in the front fenders ...
Now as far as your tire wear,if you're only driving your car on the street then -1 front and -1.5 rear is all the camber you will need as well as 1/16 toe in at all four corners !

You have a nice car,spend the money to get it aligned and corner balanced by a pro,you will enjoy it even more afterwards :)

Cheers !
Phil

Ok... This is what the consensus is thus far. Raise the rear fender height by re-indexing the torsion bars at least one notch. This is gonna suck becuase getting the spring plates back off with the new bushings should be a fun chore. I'm gonna need to make a special puller for this I'd bet.

MY new targets are below..

FRONT SUSPENSION: Specifications
US spec Euro after new bushngs Target
Trim height: 99 108 136.5 136.5
Wheel arch height: 24.625 24.625
Camber LF: -1 -1
Camber RF: -1.7 -1

REAR SUSPENSION: Specifications
US spec Euro after new bushngs Target
Trim height: 37 16 38.1 16
Wheel arch height: 25.25 25.75
Camber LF: -1.5 -1.5
Camber RF: -2.7 -1.5

Rake: 1.7 ??


Please chime in and I'll keep everyonen posted as I move forward on this.. SmileWavy

Third time is the charm.. I think I've got her licked now... The second time the rear wheel arch height was too high. :(

do a google search for 911 home alignment , It will give step by step info

What a pain in the ass this is... 4th time might be the charm.. I need to index 3 increments and then I should have it. Tomorrow night. I'm done being frustrated for tonight.

Thank you very much... If I measured correctly., I m currently running the following:

Trim height: 144.5 mm (front) which is 24.875" to the fender lip.
Trim height: 11mm (rear) which is 26" to the fender lip.

I'm planning on setting the front camber to -1 deg. and the rear camber at -1.5 degrees.

Ok guys.. After the corner balance the trim heights came out as follows:

FRONT SUSPENSION:
toe: +1/16" (out)
Trim height (LF): 134.9375
Trim height (RF): 136.525
Wheel arch height (LF): 25"
Wheel arch height (RF): 25.5"
Camber LF: 1.46 DEG. OR (15/32")
Camber RF: 1.46 DEG. OR (15/32")
CASTER: 5.5 DEG. (BOTH SIDES)
(LF) UPPER WHEEL FLANGE (INBOARD FROM OUTSIDE SURFACE OF FENDER): 1 1/16"
(RF) UPPER WHEEL FLANGE (INBOARD FROM OUTSIDE SURFACE OF FENDER): 1 1/8"

REAR SUSPENSION:
toe: -1/32" (in)
Trim height (LR): 23.8125
Trim height (RR): 23.8125
Wheel arch height (LR): 25.375"
Wheel arch height (RR): 25.625"
Camber LR: 1.1 DEG. OR (11/32")
Camber RR: 0.49 DEG. OR (5/32")
Spring plate angle LR (unloaded):
Spring plate angle RR (unloaded):
(LR) BOTTOM OF TIRE (BULGE) OUTBOARD OF THE OUTER SURFACE OF THE FENDER: 7/16" (TIRE STICKS OUT 3/16" FURTHER THAN RIGHT-REAR)
(RR) BOTTOM OF TIRE (BULGE) OUTBOARD OF THE OUTER SURFACE OF THE FENDER: 1/4"


The front camber is -1 deg. (front) and -1.5 deg. (rear) as stated by my pro wrench. I am not getting close to those numbers but I'm not using slip plates either. It doesn't seem to me that the slip plates are going to make that much difference. The slip plates are only for allowing the tire to move while adjusting... Correct??? :eek:

What I don't understand is how the trim heights can be so close side to side and the fender heights are way off???

Corner balance came out as follows:

LF: 606 lb
RF: 599 lb
LR: 990 lb
RR: 950 lb

38% (front) at 1196 lb, 62% (rear) weight at 1940 lb.

cross weight is: 1565 lb.

Any comments on if this looks good or not?

Not sure who did your alignment but somehow i think that there's something wrong with the numbers ...
First off you have toe out in the front which will make your car darty on the street and second of all, your camber numbers seem off to me.I would suspect that you should have -1 in the front and -1.5 in the rear,not the other way around.
That's just me,but i'm sure everybody has an opinion on this !
Your castor numbers are good ...

Just sayin ...

Cheers !
Phil