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Thu Mar 22, 2007 3:04 pm

Hi,

I have a problem with my 1970 Fastback. Since I have bought the car five years ago, I saw a positive camber in both rear wheels ( as in the photo). Recently I have changed the four rubber bushes of the torsion bars, but the rear wheels still have the negative camber angle, and this inclination causes excessive wear on my tires.

I have a Bentley VW Type 3 Service Manual, but there has not mention about the adjustment of the rear wheels.
Would anybody help me with information about how to solve this problem? How can I regulate the rear wheels camber?

Thanks

John

1970 VW 1600 TL Fatsback

Thu Mar 22, 2007 3:11 pm

that looks alot like the rear torsoins have settled and that in turn causes the negetive camber. you will need to re-index the rear torsions and it will probably require turning both inner and outter splines to get the correct about of change. free $ amount to do, expensive time unless you are good with a protractor and at the math and figure out the rate of change needed ahead of time.

Thu Mar 22, 2007 3:28 pm

1970 is IRS, so torsion bar settling shouldn't have a strong effect on camber. In fact, that photo makes the rear look very high (not low as settled bars would cause), in addition to having more negative camber than spec (which is only about 1-2 degrees if I remember right). When you replaced the bushings, did you set the spring plate angle to the correct spec? That is well-covered in Bentley.

Thu Mar 22, 2007 4:43 pm

I'm no expert but that looks unusual.
IRS should not have that much camber at that height as you probably know.
Your car looks mostly level as well.

Did you replace the bushings yourself?

Is there a chance that the inner, right bushing could have somehow become 'caught' on the lower edge of the engagement area?

You car looks really clean but could the whole rear trailing arm (not springplate) or the end near the CV have become twisted somehow by corrosion or a crash?

Mon Mar 26, 2007 8:15 pm

Many thanks to all.

I am going to consider your recommendations. I have reviewed the Bentley manual again and I have found the rear wheels alignment instructions.

The next weekend I will check my car in the workshop.

John

Mon Mar 26, 2007 8:20 pm

By the way, the "inward at the top" stance like yours is called negative camber, not positive camber. This might otherwise be confusing as you read Bentley if you have it backwards. Good luck with the work!

Mon Mar 26, 2007 11:49 pm

please keep us posted.
I'd like to know what the issue is.

Is the car level when measured from each rear tire position?

Got a picture with the wheel off of the spring plate?

Fri Sep 16, 2016 7:52 pm

I'm having the same issue as the original poster but I have a 65. Never lifted or lowered a car and don't want to mess it up. What's my best starting point to find and correct the problem?

Fri Sep 16, 2016 8:16 pm

I had that happen to my 73 SB many years ago. I came out of work and had a flat and looked and I could see the steel belt all the way around both rear tires.

In 98 I got larger gas filled shocks only because when I got the new tires they pointed out the right front leaking so I went to a very small independent VW parts and service place, it is difficult to describe without an entire post .

He could get anything and he suggested forget the brand larger dia gas filled for the rear and original size gas filled for the front. I didn't check the height before it seemed a bit higher and those tires and the ones after wore even. I would think the toe which can be adjusted would do the same thing.

Fri Sep 16, 2016 11:34 pm

If I was a gambling man (I'm not) I would put my money on bent trailing arms. Over the years I have seen this in many, many cases especially since I drive one of my VWs in the off road realm. In fact when I got my 73 Squareback, they were bent as well. What people don't realize is that our trailing arms have seen 40 years of abuse from just driving down the road. Think about all of the pot holes and bad railroad crossings that have been hit in 40 years, then add in metal fatigue and the arms bend.

In reality, the arms do not bend, but instead they twist at the stub axle bearing carrier. When you look at the torque vectors that are inflicted when the rear tire hits a bad bump (especially square edged, or even worse, bottoming), the tire/wheel tries to travel upwards. However, the torsion bars are trying to prevent this motion, and in the case of bottoming, the stops arrest this motion. Yet the tire/wheel still has an upwards force on it. Over time something will give, and due to the direction of the forces, this motion is inwards at the top of the tire/wheel.

In a worse case scenario, I have seen one impact cause this to happen. A buddy and me were hammering it in our Bajas in the desert around Ridgecrest and we went off about a 3' drop off. Both cars slammed down and bottomed hard, but my Baja had reinforced trailing arms, and my buddies didn't. I was able to finish out the rest of the week in the desert, but not my friend. The trailing arm that took the brunt of the impact was so badly twisted in at the top, it looked like a swingaxle car that had been slammed to the ground.

There are two ways of fixing the problem. If you know of a good frame shop, they can straighten the arms. The other option is to replace them. If replacing, they are NOT a Type 3 specific part. You can also use the trailing arms from a dual spring plate type 1 (69-70). In fact, that is what I used on my 73 Squareback. I can not say for sure if the single spring plate type 1 arms will work, but I imagine that if the spring plate hole line up, they could be used as well.

ibjack,

Since your car is a swingaxle, I would go with sagging torsion bars in your case (this is normal for the age). Grab a magnetic level from harbor freight and your Bentley, then compare the angle of the spring plate to the bottom of the door jam. I suspect that they will not be in spec, and a re-indexing of the torsion bars will fix your problem.

Sat Sep 17, 2016 5:25 pm

I don't know it seems odd to me the the control arms would bend and both the same amount visually. I can't see it being over loaded since it's a FB .

The car is not that heavy even though most of the weight is at the rear and that's the engine and diff and trans . which are not really heavy . I suppose some really good hard hits in pot holes might do damage.

I haven't read or seen much about this here.

Sat Sep 17, 2016 6:23 pm

That is the typical response I get, IT CAN"T BE THE PROBLEM.

I guess that part of it is that most people do not have the ability to pre-visualize the static or dynamic forces that are in action on a given part. Of course, back when I thought I wanted to be an engineer most of my classmates could not see them either. I could see the forces, but I didn't know how to apply the appropriate math - good bye engineering.

If I were to bring this subject up in the off road forum, the reply would be Duh, tell us something we don't know. But even in the Type 1 forum, I get met with extreme doubt. So the poor OPs change the torsion arm bushings, the trailing arm bushings, hell even the stub axle bearings. Then they spend more time trying to adjust the trailing arms at the spring plate. Then out of the blue, I'll get a PM telling me that they finally swapped out an arm, and everything is aligned once again.

Except for in the off road forum, I have never seen one particular subject been met with such strong disbelief. Yet I will continue to stand on my soap box, and explain it the best I can, and continue to take the heat. Because I know that every once in awhile I have saved someone a lot of time hassle and money.