rear wheel angle

[titan3c]

some months back I replaced the rear shocks on my 411. Today I was in a position where I could see the rear of my car from some distance, and noticed that the rear wheels angle out at the bottom. I checked them with a level, and yes they aren't straight. Is that normal or did I goof something in replacing the shocks?

[raygreenwood]

Really its doubtful its anything you did.

With age all type 4 get some extra camber in the rear wheels.
Its caused by two things.

1. A little of it is caused by sag/wear in the rear rubber trailing arm pivot bushings. As long as tbey are not just shredded....leave them alone. If the trailing arm has slipped to one side...meaning the arms of the trailing are are no longer centered in the yokes.....we can talk about that.....but that is usually maybe 10% of the camber issue.

2. Most of it is just long term sag in the trailing arm.

There is no adjustment provided....but it can be adjusted.....but its a pain in the ass....and at worst requires pulling the rear trailing arm off. At best....with some crafty-ness....and is easiest to do on a lift.....it can be adjusted by a bit of grindkng and modifying one part.

But first.....I would have the alignment checked to see how bad it really is. The specification is -1° +/- 1°.....so as long as its not over about -2° to -2.5° maximum....I would leave it alone and just be sure to rotate the tires every 5k miles to keep wear distributed.

But....if you want or need to fix it....and make it permanently adjustable....I can post how to.

A quick description.....
Basically its like this....

The rear trailing wishbones are adjustable from the factory ONLY for toe-in. If you look underneath you will notice that the inner bolt on each trailing wishbone is an eccentric head boot and carries the pivot bushing in a slotted yoke.
When adjusting the toe-in....after you set the adjustment at the alignment shop....the car must be lowered and resting fully on its wheels when you tighten that inner eccentric bolt because the faces of the bushing are knurled to lock tight against the mounting yoke that is bolted to the rear cross member. If the car is jacked up.....when you tighten the bolt....it will cause the rubber bushing insert to wind up and twist in the housing.

So.....for camber adjustment.....you would really only need to move the inner mouning yoke/bracket that is bolted to the rear cross member.....vertically....so it pivots the wheel.

But.....the slotted holes this bracket is bolted through.....are slotted horizontally to set the rear suspension track width....and not vertically.

So what you need to do....simply put......is pull the trailing arm loose.....and grind those horizontal slots on the top edge to enlarge the amount the bracket/yoke can slide upward.

There are a couple of issues with this.
1. On the forward side of the rear cross member there are large washer plates that the nuts are tightened onto. They are kept from sliding around by stamped in ledges. You can see this if you look at the forward side of the cross member. These will not allow the washer plates to slide upward and you do not want to grind those ledges off.....so you also need to slot the holes in the washer plates so the yoke can move upward while the plates stay in place. Not too hard with a die grinder or drill press.

2. The rear cross member is hollow. Its pretty thick...about 1/8" metal.....but to keep the torque on the nuts from crushing that hollow cross member....there is a floatkng block of aluminum or steel that is inside with two holes in it for the studs from the mounting yoke bracket to pass through.

So what you can do......is grind the slots through the rear cross member on the top edges onpy.....but you have to do it on the engine side and the forward side......then.....on the bottom side right under that spacer block inside.....drill a 8-10mm hole. Thread it.....or weld a nut on the outside. Insert a bolt with a lock nut.

Once you have ground the slots to give the inner trailing arm mounting bracket some vertical play....you loosen the two big 19mm nuts.....and then use the 8-10mm nut underneath...to drive the spacer block upward.....which pushes the yoke upward. When you have the alignment correct....lock the two big nuts...and the lower lock nut.

Then loosen the two big nuts of the outer yoke mount to take strain off of the outer trailing arm bushing and then tighten them back up.

I thought I had posted sketches at some point. If not I will look and post some. Ray

[Lars S]

Agree with Ray, dont thonk this has to do anything with your shock replacement.

Personally I always thought that the "normal" camber of Type4's is more then the specified one degree...it is clearely visible on most cars. (but after all one degree is about 10mm from top to bottom of the tire so that should bee seen)
This factory drawing shows that it obvoiusly was visible on new cars.

/Lars S

_________________
Porsche 914 -72, Bahia Red daily driver
VW411 2-d -70, White, sold
VW412 4-d, -73, Gold Metallic, daily driver
Suzuki T500, -69, Candy Gold, sold
Suzuki K50, -77, Black, daily driver
BMW R69S -69, White, sold
Husqvarna 118cc, -47, Black, Sold

[titan3c]

The angle looks exactly like the Lars illustration, I just had never noticed it before. I'll check out measurements and Ray's suggestions to see what I think I should doe if anything. Thanks Bob

[Lars S]

Personally I would rather have a bit more then less the specified angle (one degree), helps to stabilize the rear...imagine an angle in the opposite direction

/Lars S
_________________
Porsche 914 -72, Bahia Red daily driver
VW411 2-d -70, White, sold
VW412 4-d, -73, Gold Metallic, daily driver
Suzuki T500, -69, Candy Gold, sold
Suzuki K50, -77, Black, daily driver
BMW R69S -69, White, sold
Husqvarna 118cc, -47, Black, Sold

[raygreenwood]

ok....this one is a little hard to visualize and explain unless you have had your trailing wishbone off and crawled around under these things.

But here we go.....

For orientation:

Looking from the top:
In the red circle shows the inner trailing wishbone mounting yoke.bracket. this inner bracket also has the eccentric bolt for adjusting toe in.....but in order for the wheel to move like the yellow arrow shows...stand more upright....this inner bracket must move vertically upward...toward where we are looking from in this view.
this causes the trailing wishbone to pivot slightly about the outer bushing axis and move the wheel.

The pink transparent block pointed out by the upper yellow arrow....is a spacer block that is inside of the rear cross member. It has either round or slotted holes drilled through it to match the slots in the cross member that the yoke mounting bolts go through.
Its sole purpose it to keep the torque from the yoke mounting bolts from crushing the cross member.

It floats...meaning not bolted or welded down...so it can move from side to side as the yoke mounting brackets are moved.

So why is the cross member slotted?

In this view you can see the slots. The pink dotted edged square is also there to show you where the spacer block is on the inside of the cross member.

These mounting points are slotted....so that the factory techs can set the rear track width correct and to make sure its dead center on the centerline of teh car. It takes a special extension bracket tool that mounts on the centerline of the transaxle. So....MARK YOUR BRACKET POSITIONS IN THE SIDE TO SIDE DIRECTION BEFORE YOU TAKE THEM OFF.

this is looking from teh front side back. The two plates and nuts in the circle are the locking bolts for the inner trailing arm mounting yoke.
The yellow arrows are pointing to the stamped in raised areas that keep the washer plates centered.

For the record in this picture....these bolts are loose. You know this because the raised centering humps on the cross member force the plates to be in horizontal alignment. The only way they can be crooked is if the nuts are loose.

This will be a minor problem if you make this modification...as those humps do not let the plates move much in the vertical plane....so the easiest thing to do is either trim the plates or make the holes in them oval.

So here is how to adjust camber:

This is looking from the rear to the front on the left side of the car. This is what you see with the trailing wishbone removed....this normal as delivered from the factory.

Two sets of slots for the yokes/brackets...inner and outer. All of this work will be on the inner mounting bracket slots ONLY.

The arrows and red lines show WHAT we are going to modify., We need to grind away about 1/8" of metal at the top edge only of these two inner slots....and you need to do this on both front and back side of the cross member.

This is TOUGH, thick metal. A die grinder works ok but is a mess. Really one of the best ways is a dremel tool with fiberglass cut-off wheels. Just score a line...then slice through and cut off a sliver at the top of each oval slot and file it clean......

So it looks like this

This is the geometry BEFORE we make this modification and adjust the camber.
The green boxes show where the yokes are mounted to the cross member.

After we slot the inner holes....the inner yoke bracket...can slip upward....causing the trailing wishbone to pivot around the outer yoke bracket. The outer yoke bracket can pivot slightly in its slots by loosening the bolts.

This shows the modification of adding a "pusher bolt" from the bottom underneath the cross member.

It pushes against the floating spacer block inside. When you push it upward...it pushes the bolts going through it that are attached to the yoke bracket ....upward...making the adjustment for you...so you do not have to use pry bars to move the inner yoke bracket upward or hold it still while tightening the nuts on the other side.
Ray

[937carrera]

Just a couple of data points from me, I put my camber gauge against the rear wheels of my cars:

The variant has 3 degrees of negative camber

The saloon has 2 degrees of camber

The saloon is a little stripped out, and the springs on the variant are weak, so camber will consequently be greater.

No uneven tyre wear on the variant, so they can certainly take a bit more camber, always good for cornering
_________________
1974 412LS Variant 1.8 AN engine on twin carbs
1973 412LE 4 door Fastback / Saloon 1.7 EA engine on D-Jet

[raygreenwood]