Testing your suspension

[TeeJayHoward]

I'm taking my '81 SC in to a dealership for an alignment soon, and I'd like to make sure that I'm not wasting my money having to align it twice if they discover that my struts are worn or something like that. Is there an at-home test or two more complex than the "push down on the fender, release, make sure it doesn't bounce" method I should be trying?

[winders]

Dealership? Do they know anything about air-cooled 911s any more? I would look an independent shop with a great reputation...

[TeeJayHoward]

Originally Posted by winders

Dealership? Do they know anything about air-cooled 911s any more? I would look an independent shop with a great reputation...

My local dealership has staff who they keep trained and up to date with the air cooled stuff. They're one of those "Porsche Classic" certified techs or something like that. I've been impressed in the past when I talk to them, and their yearly running of the Pikes Peak International Hill Climb doesn't hurt, either!

[Rodsrsr]

Dealerships don't instill confidence when dealing with an air cooled 911.

[jpnovak]

The biggest thing is to check the condition of your rubber bushings.

In the front, look at the back of the a-arm, specifically the adjuster cap. The outside circumference should be concentric with the steering rack support cross member. When the bushings are worn (especially if original) the adjuster cap will be pushed toward the top edge. There will be a small gap at the top and a large gap at the bottom. This means you need to replace the bushing. Often when they are this worn the alignment and corner balance setup does not hold due to the wear.

The same is true in the rear. You want to look for concentric gaps around the spring plate and the spring plate support bracket.

I do a lot of local alignments and I will always recommend to fix the bushings before spending the time and effort to align and CB a car. It just works better after refresh.

[Jonny042]

Good advice from Jamie.

I'm going to say you're asking the wrong question.

For half the the price of an alignment you can purchase a set of toe plates and Do It Yourself:

Toe Plates - Tenhulzen Automotive | WheelAlignmentTools.com

Then you know it's done right, and you can check it in a few minutes any time you want.

This is based on the premise that the dealership isn't going to corner balance the car anyway.

[TeeJayHoward]

Originally Posted by Jonny042

Good advice from Jamie.

I'm going to say you're asking the wrong question.

For half the the price of an alignment you can purchase a set of toe plates and Do It Yourself:

Toe Plates - Tenhulzen Automotive | WheelAlignmentTools.com

Then you know it's done right, and you can check it in a few minutes any time you want.

This is based on the premise that the dealership isn't going to corner balance the car anyway.

That looks cool for toe, but what about camber and caster? Can they be used for that as well?

And thank ya kindly, jpnovak. I'll try and crawl up under there today, take a look at those spots.

[jpnovak]

Here is example of rear spring plate bushing wear.

Need spring plate bushing advice

Here is example of front a-arm bushing wear.

Control Arm Bushing Refresh

[Jonny042]

Originally Posted by TeeJayHoward

That looks cool for toe, but what about camber and caster? Can they be used for that as well?

Fun fact. Sometime around 1988 I got tired of doing alignments with jackstands and string and invented the toe plate. I'm sure some other like minded and equally motivated (read=POOR!) people came up with the idea by themselves later on, as the concept is relatively simple. Mine had three feet and were built from MDF and are actually still in use by a friend who used to crew for me.

Of course that doesn't help you get your wheels all pointed in more or less the same direction......

You can get the Tenhulzen toe plate with the angle finder thingie built in so you can measure camber, if you want.

Toe is always going to be the big thing and the plates are the most convenient way to measure it. Everything else can be measured using your head and a few simple tools.

Camber I measure with a custom built tool that looks suspiciously like a 1" square tube cut to length. Since it's ferrous a magnetic angle finder works on it. The other even easier option is a 24" carpenters level and a measuring tape. Use a bit of trig to figure the angle or just eyeball it.

I set the caster the same left and right by eye using the strut top mounts, If this doesn't work for you your car is badly bent and no professional alignment will help. You can tweak the position on each side to account for road crown but I prefer to leave it even.

Getting the thrust angle of the rear (ie, you don't want the car to crab) and the steering wheel centered in front can be done by sighting down the toe plate to a tape against the center of the wheel at the other end of the car.

I've had the results from all this DIYfoolery checked on a state of the art alignment rig and they are spot on.

Now, as for corner balance, I don't have a super clever or cheap way to measure that since I own corner scales. If I wasn't an ex roadracer I wouldn't have them, but if left to my own devices I would simply set the rear spring plate starting angle to the same angle left and right, and buy two 440 pound shipping scales to weigh the front end and make sure I was close to even weight on the front end with the car empty. The corner weights on a 911 are surprisingly symmetrical, and in my experience doesn't suffer corner weight change when you hop in and out of the drivers seat so you don't need to be all that hung up on that.

[TeeJayHoward]

Originally Posted by Jonny042

Stuff

This forum needs a "Like" button.

Originally Posted by jpnovak

Here is example of rear spring plate bushing wear.

Need spring plate bushing advice

Here is example of front a-arm bushing wear.

Control Arm Bushing Refresh

Yes! Photos! Thank you!

[Jonny042]

On second though 440 pound (200kg) scales aren't going to quite do it for you. Better go with 660 pounds (300kg). I assume your car will be quite a bit heavier. PS - this was on a terribly uneven surface I was just going for total weight.

[Old H2S]

How much stuff did you get rid of to get down to 2200?

[chrismorse]

Hi TJ,

JP's point is that if the suspension, particularly the rubber bushings are worn, it doesn't make a lot of sense to spend good money to align the car, because, you will have to do it all over again, after getting the corner weights reset after doing bushing replacement.
If, the bushings are not trashed and you are not a hard enthusiastic driver, get it aligned and enjoy the car.
Most of the posters are hard core - replacing all worn parts, many times with more performance oriented parts, then getting the corner weights right before alignment, so that the car will perform, as good as new, or even "better".
I am way over the edge on this, but if your car is mostly a driver, and or funds are a bit tight, just get aigned if the bushings are not toast.
There is an infinite spectrum - good luck with finding your "spot".
A huge amount of great professional help on offer here,
chris

[Jonny042]

Originally Posted by Old H2S

How much stuff did you get rid of to get down to 2200?

It's basically a longhood build on a non-sunroof 78 911SC tub. All steel, including the bumpers, but I paid attention to the weight wherever I could, took out every extraneous wire and doo-dad. Aluminum engine lid, aluminum bumperettes, aluminum license plate panel. Full interior, with heat, rear seats, and sound deadening. You can read all about it here:

Project Heavy Metal - an all steel classic, remastered

If it didn't serve a useful purpose, it didn't get bolted back on

[icarp]

To encourage the weight loss program.
Kermit
1980 911 SC , sunroof , RS clone , 3.0 CIS, glass front and rear bumpers ,
RS seats , RS door cards, rear seat delete , RS carpets , Smaller battery, Glass duck tail , 15"x 7" and 8",
Stock T bars and sway bars , spare tire delete , weighing on plates to .040" to dead level , Lots of fun.

[icarp]

Kermit out playing in NM

@2260lbs

[winders]

Is that with driver?

[Jonny042]

Originally Posted by winders

Is that with driver?

I wish!!!

Mine is with a completely empty fuel tank and no spare but ready to drive otherwise.

Ian - have you noticed when doing cross weights that if you set it to 50% without driver, then get in, it doesn't change?

I still can't wrap my head around how that's possible. Obviously the left side weights go up a bit more than the right, but the fore aft location of the cg of the driver must almost exactly match the front/rear weight bias of the car.

[icarp]

Jonny,
This is the weight with me in it . When I know I'm going to the track I'll set the car up this way. When it is just street driving , I'll set the car up "even" with me out of the car, the first scale shot @ 2260 lbs . with 5 gal gas
The reason for this , I usually have a passenger , and I often have them drive the car . This balance works very well for them. They get to experience a well balanced car with good habits . As I am driving alone , I do not mind the difference at all. It helps to keep me tuned in to the nuances of the car .

These are the practices that I include in my set ups , they seem to work well for me .

[Jonny042]

I found an old post and a scale pic from my first setup - 25 pounds of fuel and heavier whee;s/tires:

Originally Posted by Jonny042

So I messed around with that for far too long, dropped the car back on it's wheels, and things started to make a lot more sense. I can't even describe how amazed I am at the following:



What's even more amazing, is that if I sit in either seat, the cross weight changes less than 0.1%!! I don't even know how that's possible. Dumb luck with the vairables of weight placement in the car I guess.

When I get in the car (either seat) it stays at 50% exactly!!!