mrdraco

My 993 has just returned after having the suspension fixed. The previous owner had screwed it up badly. The rear sway bar was frozen and the shock collars were so low as to make the suspension useless . After the work, a 4 wheel alignment and corner balance was done.

I am concerned about the front suspension now. ALL the rake is gone and the front fender height is higher that the rear. I also feel the front end "bouncing" a bit more, of course it wasn't moving at all before. This doesn't seem right. The specs are below.

Corner Balance
Left Front: 647 Right Front: 610
Left Rear: 940 Right Rear: 898

Front Weight: 1257 Percentage: 40.7%
Front Weight: 1838 Percentage: 59.3%

Car weight with driver: 3095

Fender Height
Left Front: 24 13/16 Right Front: 24 13/16
Left Rear: 24 3/4 Right Rear: 24 3/4

Alignment
Front
Camber Left: -1.0 Right: -1.0
Caster Left: +5.75 Right +6.0
Toe In: 1/16

Rear
Camber Left: -2.0 Right: -2.0
Toe In: 3/32

Before and after pictures: The second pic is in the rain(still raining now) so the quality is lousy.

kkim

There should be a 1 degree forward down rake. Easiest way to measure is laying a protracter on the door sill.

Was the kinematic toe set properly at the time of alignment?

mrdraco

The alignment specs list "toe in", is this the kinematic toe?
Front
Toe In: 1/16

Rear
Toe In: 3/32

kkim

No, kinematic toe is set when doing the rear camber adjustment. It takes special tools to set it correctly. You may want to find out if your alignment shop had the correct tools to do this job as KT can really affect handling.

Also, a cheap protracter from sears can be used to check for proper rake angle.

cabrio993

Your fender height of 24 3/4 rear and 24 13/16 front is 1/16th of an inch difference. You can say that your car is setup at 24 3/4 all around.

How full was your gas tank when you took these measurements? How much gas was in the car when the ride height was set by the shop. Expect 1/4 of an inch difference from a full tank vs an empty tank. Your toe in changes too as the gas tank gets empty, nose raises, front tires toes out.

Do you still have the same tires from the previous owner on? It may take few hunderd miles before the tires wear out to the new alignment settings, that could explain your unsettled feeling up front.

mrdraco

Don't know about the kinematic toe as the alignment was outsourced to a specialty shop.

I have a protractor, where do i measure the rake angle?

mrdraco

The tank was 5/8 full. Tires are brand new PS2s, same size as previous.

kkim

First off, this is the type of protractor I'm talking about.




With the door open, you can place it on the door sill.

You really should find out who did the alignment and ask them if they have the proper tools for the KT alignment. Many shops w/o the proper tools just max out the adjuster and call it good.

Also, as pointed out, your fender height measurements are about even. IIRC, when the rake is set properly, the front fender height usually is about 1/2" higher than the rear. If anything, it sounds like the front is too low.

You might want to consider having the corner balance, height adjustment and alignment redone or taken somewhere else that knows what they are doing.

c993k

I loved the way that car looked when you first showed it to us. The previous owner should be able to answer any questions about the way it was set up. Have you contacted him?
By what you are describing I think a new suspension system is in order. It's not that expensive and it gives you peace of mind to you know what you have is perfect, not something that has seen a lot of track time. Chris

mrdraco

I have a simpler protractor I use to measure angles when building my plane. My main concern was finding a line on the car that was going follow the rake angle.

kkim

And from what I've read in past posts, the door sill is that line. Give it a try and see what you come out with.

Ponchobroke

Kelly is ABSOLUTLY correct..KT is critical. I would make certain you question the shop who did the work directly. The least it will do is to keep you from looking silly (stupid) when the car makes a move you didn't expect at a critical time!



p.s. Kelly sorry to hear you leaving us for a while

Dudley

Be careful with fender height measurements, they do not always correspond exactly with the actual frame measurements used in setting the height. Mine did not. It is also unusual that your fender heights would correspond exactly from left side to right. I might expect some slight difference resulting from the adjustments for corner balance. Mine did. Kelley is right on - take it to a shop that can answer your questions. BTW - Nice car.

Bull

It is generally correct that the rake angle of the car will be right when the front fender lip is approx 1/2 inch higher than the rear.

viperbob

I will assume for a moment that the shop that did you alignement used the proper frame points to set the ride height, and that the wheel well measurements are just a result and that your car is square. Now, I hope you have EVO uprights as your car is way low and I can tell you for a fact that it is going to have some serious bump steer. The statement that you made "I also feel the front end "bouncing" a bit more" makes me think that you do not and your bouncing is in fact bump steer.

Now to the specs. 1 degree more in the rear than the front?? This is not right. You are going to have a great bit of under steer. For street as a safety precation a half degree more in the rear than front is normal. For real serious track cars, you want MORE negaive camber in front than the rear. Also 1 degree in front is nothing. With camber plates you can get up to about 3.5 degrees. I use to run -3 front and -2.7 rear. Of course your final settings will be a matter of your own comfort level, but -1/-2 is not good. Try to see if they can come up to at least -1.3 F and drop the rear by at around .5 to -1.5 to -1.6. This will at lest give you a car that is closer to neutral on the alignment. (I have a tough time recommending no camber diff unless I know the driver and his/her capabilities).

Now the toe. 1/16" is still a lot. If you can stand a little tram lining on the street, drop it to 1/32" (you still have good caster so this shouldn't be a real problem). At least drop it down closer to 1/32".