Rear wheel adjustment and alignment question/issue...
 

Hello,

I have an issue with the right rear wheel alignment and can use some help.

It seems that the right rear wheel is aligned so that it protrudes more from the chassis rail than the left so that it makes contact with the inside of the wheel arch in the quarter panel. It touches the tire on the outer edge.

I have had the car aligned, so the camber and toe setting are set correctly, but no change. Is there a way to pull the wheel more in the wheel arch toward the chassis rail?

I noticed that the rear end of the spring plate has sort of oval/elliptical bolt holes where it attaches to the control arm. Is this for alignment to either pull in or push out the wheel due to altering the point where the spring plate and swing arm meet?

Thanks for your help!

what are the camber and toe settings currently? Tire and wheel size?

Camber -1 degree, Toe 0 degree. I run 185/70 R15 Fulda Y2000 tires.

wait a second...is this on the '71? Those tires might be way too tall. Maybe 185/65.

185/70 on 15 inch is the correct tire size for a '71. I know that quite afew move to 185/65 because of stability.

Also, I have no issues on the left rear side, only the right. Somehow the wheel needs to get more inside the rear quarter panel.

those bolts are for adjusting alignment. If you adjust those, you adjust your alignment. If you set your camber a little more negative, the wheel will tilt in, top toward middle of the car, you might solve the rubbing problem, but you experience quicker tire worn from inside edge.

Somehow I think this 911 has been lowered or somehow altered from stock. The suspension just does not cause this to happen if everything is stock.

Your alignment and tire size are correct, there should be no rubbing.

Are you running 7" wheels on the rear? Can you post a picture of the car?

I am running 6j x 15 wheels on the car. I took some measurements from wheel to body, front spring plate to wheel, etc, and it seems that it is the wheel which stands too much outward. The quarter panel has the correct distance from the chassis rail.

I will post some pictures later. What I did notice is that the right wheel is closer to the front of the spring plate than the left, which would indicate that where the springplate attaches to the control arm must be altered so that the wheel moves a bit inward. I guess that there is some adjustment possible because of the elliptical bolt holes in the springplate.

Am I on the right track here or is my line of thinking way off?

Some pics.

http://forums.pelicanparts.com/uploa...1279612886.jpg
http://forums.pelicanparts.com/uploa...1279612936.jpg
http://forums.pelicanparts.com/uploa...1279613016.jpg
http://forums.pelicanparts.com/uploa...1279613098.jpg

wow, I don't know 71 but your car looks like it has a lot of space between the tire and fender. How is your shocks condition?

Zero toe in the rear, you might want to change that unless you are use to it. When did this happen/change, and its hard to tell by the pics?

Shocks are ok, relatively new koni's. I know, the car needs lowering which will happen this winter. Also the reason why I need to get this sorted.

I don't know when this changed. I noticed it on a long trip to Le Mans classic with more weight in the car. Thing is, my winter project is the suspension and all bushes, bearings, etc will be renewed. But I will go to the factory in Zuffenhausen in 5 weeks and don't want to go there with a tire touching the fender.

Steel trailing arms can be bent, and it can be hard to see by eye. Do you know for sure that the chassis and suspension arms are in correct geometry?

just eyeballing it, it looks like you have zero or slightly positive camber. That sure does not look like 1 degree negative.

@ Rusnak: That's what I thought as well. It looks too positive. But it has been aligned at a shop with alignment equipment and was set to 1 degrees negative. I guess that I need to trust the machine and not my eyes.

I have checked the spring plate and it is not warped. But what i did see is that the bolts where the springplates meet the control arm should possibly move backwards, so that the wheel moves towards the back of the car and inwards at the same time. I tried this, but to no avail. No movement. Does the toe or camber eccentric bolts adjust this?

Otherwise I'll just give it more negative camber so that it doesn't touch the fender, but I a affraid It will reach 2 degrees negative then. How does this affect driving????

If it looks off it probably is. Don’t trust the shop measure it yourself

Put the car on level ground and place a level up against the rim, 1 degree camber should be in .3" at the top of a 16" rim.

I just took a carpenters hook and a flat bit of aluminium. I put the flat bit of aluminium on the rim edges (bottom and top and used the carpenters hook to see if the rim is negative.

On the good left side I had a 4 mm gap at the top, so that should be 1 degree negative. On the right side it confirmed what I saw. No gap at the top, even a slight positive. So tomorrow i'll set the camber similar to what I have on the other side.

Still don't understand that the alignment equipment or the operators have messed it up that badly.

There you go. The eccentric bolts adjust camber and toe. You need to loosen the two bolts that attach the springplate to the trailing arm.

You can not just start messing with toe and camber...you can easily create some dangerous handling combined with extreme tire wear. Adding negative camber increases toe out for example, and toe out in the rear will be rather "interesting".

If you have a string alignment set up and some basic skills you can align the suspension yourself but it takes time.

Those appear to be fuchs replicas, but they also appear to be in a stock size with stock size tires. Nothing should be rubbing.

It does appear to have positive camber in the rear and that could be your problem...either that or a bent control arm. I realize you measured a difference in camber, but keep in mind your floor may not be level.

Finally...a shop dedicated to old Porsches needs to do the alignment. Alignment shops will be completely useless, and even good mechanics of other brands will be puzzled by those alignment eccentrics....they really are unique to Porsche. They can also be frustrating as hell to adjust.

I'm just guessing, but I think with the positive camber and zero or no toe that 185 shod 911 could be all over the place already.

yeah, could be!

I like a little rear toe in.

I meant the banana arm, not the spring plate. The steel bananas can bend without breaking in an impact.

You cannot rely on measurements from wheel to body panel for alignment since most cars have slightly mis-aligned body panels due to the large amount of manual labor in building the cars.

I agree that the car needs to be aligned properly. But I can't drive it now without the risk the tire rubs against the fender.

I get a tire change (shop owner is a fellow 911 driver) somewhere next week and i'll ask if they can check toe when doing it. But I need to change things now to even get there.

Garage floor is level, so using the method described should be more or less accurate. Toe for a '71 2.2 is zero degrees, so no toe-in at all. Does this make the car more nervous?

Finally, what is the correct sequence? First Camber and then Toe or the other way around?

Thanks!

Yes, camber then toe then check camber again. I use a laser level attached to a bar placed on the rim to check toe its very accurate.

The Scruggs book recommends doing toe last...If camber is off a little you're OK but toe needs to be spot on. One does effect the other.

If you search on "scruggs" you can find references on his little book, which is a great tutorial on home alignment.

Ok, I started today with "mending" the positive camber on the right rear wheel. I loosened the 2 bolts which holds the springplate to the banana arm and both the camber and Toe eccentric.

When turning the Camber eccentic, only a very slight movement was noticable in the wheel, not nearly enough to get a negative camber. I have tried different things, top bolt tight and lower loose, the other way around, but to no avail.

When I was at the specialist last week, he was able to get a lot more movement in the wheel and get it negative. What am I doing wrong? Should the toe in eccentic be tight before attempting the camber eccentric?

Also, how does the eccentric bolt work? what does it do when you turn it so that it tilts the banana arm? Just cant figure that one out.

Thanks again for you help!

You may want to take out the camber adjusting bolt and make sure it is not damaged and it is in the correct orientation. It is possible to have it in upside down. The toe bolt can be left tight, but you may want to loosen it to see if that helps. Check to see if the banana arm is moving on the torsion arm and is not frozen due to rust. You could remove just the camber bolt on the other side to see how it is oriented for comparison.
Have you had the rubbing issue before the alignment? It is possible that the banana arm is bent. They can be straightened in a press by a knowledgeable mechanic.

True the "specs" are zero toe at the rear. Most will recomend about 1/8" total toe IN at the rear, however, to make the car more stable. Zero toe or toe out at the rear can make the car scary if you lift in a corner.

Ok, I had the Swing plate seperated from the banana arm, had both of the eccentric bolts out, cleaned everything and lubed the bolts. Put everything back in place and tried again. No real change, still postitive.

When trying this, should the car be under it's own weight? I am tring it now without the wheel on and off the ground. Or shouldn't this matter.

The only thing I can think of next is a bend banana arm. But I have not done anything to bend it. Anyway, i'll give it another try tomorrow and see what happens...

Any checking of alignment is done with the full weight of the vehicle on the ground, swaybars disconnected if possible.

For the eccentric bolts to move the banana arm, the springplate (radius arm) and the banana arm have to be held together by the attachment bolts. Try tightening them to squeeze the two arm together, then loosten slightly to allow movement. The eccentric bolts will now move the banana arm quite a bit.

Try putting a dab of paint on the eccentric bolt lobe in order to not lose the orientation, and you might even grease the radius arm where it slides against the banana arm.