In Pursuit of the Steering Shimmy on Goldie

[Pepperbilly]

Trying to start the new year without the shimmy. Finally got the wagon in for alignment on the last day of the year. Here are the things I did leading up to this…

- Rebushed the idler arm with bronze bushing
- Reinstalled my good original steering center link
- Soaked all front rubber bushings and rings in Simple Green to rejuvenate
- Replaced front shocks with stock type fitting Bilstein B6s
- Repacked front strut bearings with new grease
- Replaced all tie rod ends
- Replaced steering damper with the Lars suggested Mercedes similar damper


During the alignment all the wheels were rebalanced. The previous balance was not done correctly. The ball joints which I was concerned about checked out within specs. That was a major relief! We decided to not adjust the rear end. Only toe can be changed and deemed it close enough. Camber was a bit off but have to fly with that.
The front alignment came in good. Here are the results…

Since the results were all in degrees I converted some of the rear results into degrees and minutes just to see what that was.

Driving the wagon is great. Perfect straight ahead steering wheel. Tracks straight with no pulling to either side. So happy with that. The shimmy is virtually gone but still a slight shimmy at about 52 to 56 mph. Otherwise at no other speed. It is so slight that I think I can live with it. Alignment tech mentioned that no matter what you do sometimes the tires themselves can be causing this. Not sure if I want to replace the tires. We will see.

Happy New Year everyone,
Bill

[raygreenwood]

The front looks really good. You can see how pivoting the subframe simultaneously splits the difference (or tries to) in castor from side to side while changing camber. You get more castor on one side at the expense of camber on the other.
The only way to get it closer...and its not really that difficult...is to pull both of the front subframe bolts out and either drill out the tubular bushings that are welded in....only on the rearward side...maybe 1/32 to 1/16" which will not affect the strength (really stout bushing)...so the subframe can shift forward about 1/16". Then realign using the pivot feature to split the difference from side to side. This gives you a slight amount more castor (always good) which also allows a little more movement ability to more exactly split the difference from side to side on camber.

Of course you are close enough...that if you align it with the proper weights in it....it may be dead on or at least closer. There is a lot written about what I am going to say.
After many years of working on 411/412 and also super beetles with struts...all of which have the nose high attitude in the front end, they align more accurately with at minimum a half tank of gas and about 50-75 lbs in the trunk....and at least half the drivers weight in the center of the front floor boards....ignore what the books and alignment techs say.

As the front chassis lowers slightly with normal weights, the relationship of the strut angle to the chassis and control arms changes. it increases static castor slightly and changes camber slightly.

Having worked on and driven these things for pushing 50 years....trust me.

On the rear, you really should get rid of that excessive right side toe-in. It may not seem like much but the 411 and 412 have quite a bit of forced "steer" from the rear on curves and during braking. It has a pronounced effect in these cars because the rear weight pushes the chassis.

Its a REALLY simple adjustment because the inner side of each trailing arm g
has an eccentric adjuster bolt. Takes about a minute to adjust rear toe.

Now.....the rear camber. it may be late spring when I get under mine to install the rear disc brakes...but when I do I will install the rear camber adjustment and post a how to.

Its really simple to do. You need a Dremel tool or die grinder and a drill with about a 1/2" drill bit...but the rear trailing arms have to come off.

its pretty simple.
1. jack car up and remove wheel
2. put spare jack under trailing arm
3. remove lower shock bolt.
4. remove upper shock nut.
5. remove shock.
6. disconnect outer link and swing sway bar down out of way.
7. lower jack under trailing arm and remove spring.
8. take large C-clamp and clamp it on one side of either the inner outer trsailing arm mount on the beam just as a marker stop to get the trailing arm back in the same spot
9. This part sucks...disconnect the brake soft line and cap both ends for now.
10. On the forward side of the beam you will find two nuts on the outer trailing arm mount and three on the inner. Remove them and set the trailing arm on the floor.
11. On the beam...you will see three slots that the inner trailing arm studs went through and two on the outer side. You will only be working on the three slots on the inner side.
12. With a scribe and a sharpy marker....draw a line ABOVE each of the three slots in the beam...on both sides of the beam forward and aft.
13. Take the die grinder or dremel and grind or cut that line. You are making these three slots HIGHER.
14. You will notice that there is a free floating aluminum allow spacer inside of the beam that the three studs go through. This keeps the beam from collapsing when you torque those nuts.

15. On the bottom side of the beam right under that spacer...centered where the inner trailing arm mount will be...drill a 29/64" hole (if you plan to use a 1/2"-20 bolt). Or you can use a 13mm x 1.5 bolt. You can probably even use a 10mm bolt but using a larger diameter with fine thread means that there will be enough metal just to tap the plate and you will not have to weld on a nut on the outside.
When you go through it will push that aluminum spacer up a little. Tap the hole.
16. Take the three hole washer plate on the back and grind a 45* bevel on the top edge of it on both sides of the car.

17. Reassemble everything.

What this does:

When you are getting the car aligned and need to adjust rear camber, you crack open the three nuts on the inner trailing arm mount on both sides of the car. Lift the car up so no weight is on the tires...and turn that vertical 1/2" bolt that you installed. It will push the aluminum spacer up...lifting the inner trailing arm mount and decreasing camber. Lock the three nuts tight then set it back on the ground and check camber. Repeat until its right.

Really, if you have teh car off the ground and the trailing arms are at full extension...you can simply check the angle of the wheel on each side. If for instance you need to change camber by 0.5*...just put that adjustment in while its off the ground, lock it and you will be really close.

I found out this works a LONG time ago in high school. I was able to grind the three slots on each side...but at that moment had no time to install the adjuster bolt that helps keep it in place while you lock it down.

Ok....the tires and wheels.....if you ever get to take the tires off the rims and then spin the rims...you may find that one or more has a spread spot. The original rims are kind of soft steel. Any 411, 412 or pretty much any ACVW that has sat still for long periods...even worse if it had flat tires...has slight spread spots.

On the other hand....and this is a no shit great thing. Find someone with a "road force" balancer machine. I have had to have this done on my Golf. It gets rid of the balance issues that garages keep having.

Check this out https://www.youtube.com/shorts/Vt88Jq18idw

This guy explainsa little more about it but it is not correct that this is only necessary on tires that have lower profile sidewalls.

Our cars are VERY sensitive to tire roundness, spread etc....because our front end has such low mass, we run less air pressure and we have very long suspension components that leverage and multiply vibrations.

https://www.youtube.com/watch?v=DQxVAssnbp8&t=60s

Lastly, if you are not using a rebuilt centerlink or if you centerlink is old....this last bit of shimmy can come from the centerlink.

Ray

[Pepperbilly]

Ray,

It was my call on not messing with the rear end. Because everything on the rear is still original stock, except for the new Econoline gas shocks, I was a bit apprehensive about touching anything. Maybe someday when I feel like rebushing the arms I will do more at that time.

Yeah I reinstalled my original center steering link because the NOS link I bought was trash. Could be my original is not perfect. Someday I will go ahead and rebuild the link I bought and keep it as a spare.

This was a very good alignment and suspension shop that did my alignment. They do alot of exotics and restored classics… lots of Porsches. I did talk to the tech while he was working and told him that you had mentioned the wheel spread issue. He seemed puzzled about that idea and never really heard of it. Could you explain that wheel spread issue in more depth?

Bill

[raygreenwood]

[redhot]

Guessing it is simply the tire flanges being deformed outwards - maybe symmetrically or not between inside and outside faces?

Flat spot on tires is easy to understand, in some sense I guess both processes is some kind of slow creep of the material?

[raygreenwood]

[raygreenwood]

It used to be that I could fin pictures of VW wheels without tires to get the cross section shape but I cant seem to find one for the life of me....but these will tell you what you need to know.

First, when the rims get a "flat spot"....and NOT talking about one caused by hitting a huge bump....which can usually be easily seen because either the whole rim is bent at its mounting flange so you see the wobble......or the rim has spread and the inner and outer beads are further apart at one point. I can catch those in the driveway with the car up on a jack so I can sprin the wheel and look at it or measure it.

The "flat spot" I am speaking of usually DOES NOT spread the outer edge of the rim. Its almost impossible to detect just by spinning and observing/measuring...with the tire on.

This rim cross section is of a fairly modern rim taken from the Tire Rack website....but its kind of close in shape to our old air cooled rims.

The yellow arrows point to the areas where the weight of the vehicle when the car is resting on the rim when the tires are flat...bends these areas slightly. It is more like creating a low spot.

While on one hand, this mainly causes an up and down oscillation as the low spot comes around to the pavement....if the area that bent is say...only on one side....the longer arm of the cross section....it ALSO changes the slant of that side so it causes a slight squirm or side to side oscillation.

Also remember that this bent area will only be about an inch or two wide.

The above series fo wheel cross section, the site I took this graphic from says thesee have all been discontinued on all modern vehicles except for some trucks, vans and trailers.

The one I have circled is very similar to what we have. I have pointed out the areas that bend or "flat spot". The right hand arrow points to what I was calling the long side above. You can easily see that when that area gets a slight bend...it really will not cause the bead to spread much if at all...but it creates a "slant" to the rim and a low spot.

The only way to catch this when you suspect it is to remove the tire...roatate the rim with some light playing across it and watch.

The cars that have this the most....are especially the ones that sat for years in salvage yards and back yards....on flat tires...when the trunk and whole vehicle was full of someones parts stash. Lots of extra weight on the rims.

Also....by the age these wheels are...none of them are perfect. They have driven a lot, hit a lot of bumps, sat still for years, have some rust etc.

If you are chasing down shimmies....and have to buy new tires....its worth it to take the old ones off the rims and really spend some time checking them out.

Ray