Lowering by adjusting spring plates - any experience?

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Dirk Heinrich
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Lowering by adjusting spring plates - any experience?

#1 Post by Dirk Heinrich »

I lowered the front (dropped spindles) and the rear (spring plate adjustments) of my 1963 VW bug successfully. This gave me the confidence to try to lower the rear of my 356 (front is already lowered with adjusters).

- Has anyone here done it? I expect the unexpected, but it would be nice to get some upfront warning.
- How do 356 cope with negative camber?
- How many notches (inner or outer) would I need for maybe 2" lowering?


Thx everyone!

Dirk

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Rink Reinking
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#2 Post by Rink Reinking »

Dirk Heinrich wrote, in part:

1- Has anyone here done it? I expect the unexpected, but it would be nice to get some upfront warning.
2- How do 356 cope with negative camber?
3- How many notches (inner or outer) would I need for maybe 2" lowering?

-------------------------------------------

1- BTDT. Much like doing the VW. Don't worry, be happy.
2- Okay with moderate lowering, horrible with too much lowering... poor handling, awful ride.
3- Start with an adjustment that will give about 3/4 - 1 degree of negative camber. Then raise the front up to match (i.e. make the doorsill level).

Have fun.

Cliff Murray

#3 Post by Cliff Murray »

I think 2" is too much. I bought a car that was lowered and drove it very little until I got sick of crashing over every bump in the road. The car also had problems with the folcrum plates in the differential galling the axles which is a byproduct of extreme angularity caused by lowering. I run my cars with 1*(or less) less rear trailing arm droop. This will give you a little negative camber. Trailing arm angle must be even side to side or the car will feel unbalanced.

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Dirk Heinrich
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#4 Post by Dirk Heinrich »

1 1/2" would actually do it. Does anyone know, how many notches on inner or outer splines of the torsion bar that would be? I do realize that I might have to combine some inner turns with outer turns to achieve that - is there a list for the various lowering combinations.

Thx again,
Dirk

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Mark Pribanic
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#5 Post by Mark Pribanic »

Dirk,
I did this about a year ago. Not sure if I recall correctly, but it was all trial and error. I believe I rotated the spring plate up one notch. This lowered the 356 to much. I then went down one inner spline.

Again, not sure if I described it correctly. But the thing to remember it was trial and error for me.

Before:

Image

After:

Image
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Tom Farnam
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#6 Post by Tom Farnam »

GET THE FACTORY WORKSHOP MANUAL FOR YOUR CAR AND FOLLOW THE PROCEDURE DESCRIBED IN THE MANUAL. My recollection (without looking) is that the B/C manual says each spline is 19 minutes of angle, and you must adjust equally on the inner and outer, but CHECK THE MANUAL.

Tom
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Dirk Heinrich
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#7 Post by Dirk Heinrich »

Thx everyone. Yeah Mark, I'll end up doing the same - trial and error. The only problem is that it might take forever putting everything back and on again!

One of my guidelines will be the following:
with a leveled car on the jack stands, wheels off, and axle tubes detached from the "radius arms" one should be able to measure the change/effect from the ground to the end of the radius arm after playing with the splines. This worked well with my bug .. so let's see here then. I am planning on doing it Friday/tomorrow.

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Mark Pribanic
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#8 Post by Mark Pribanic »

In reading the B/C workshop manual I have. I found that their are:

40 inner end splines
44 outer end splines

It also stated the correct factory adjustment of the torsion bar, unloaded(jacked up) radius arm reading using protractor VW 245a is:

Coupe/Cab/Hardtop:

16Degrees at 30"

Roadster:

14 Degrees at 30"

& for a Super 90 Coupe/Cab/Hardtop(with compensating spring)

15Degrees at 30"

& for Super 90 Roadster:

13Degrees at 30"

Anyone got the tool VW 245a they want to sell? j/k
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Dirk Heinrich
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#9 Post by Dirk Heinrich »

Thx again Mark!

Do you have any camber issues though? Would you maybe have a pic from the back of your car showing the angles of the tires (no load)?
From your pictures I am guessing you went 1 1/2" lower - what would you say?

Dirk

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Mark Pribanic
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#10 Post by Mark Pribanic »

Yes, it is very close to 1.5 inches. It has been almost a year & a half now. I have not had any camber issues nor excessive tire wear.

Per your request here are two pics from July 2007 with unloaded weight...

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Image
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Norm Miller
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Adjusting the rear camber.

#11 Post by Norm Miller »

A WORD OF CAUTION:

DO NOT HAVE YOUR ARM UNDER THE SPRING PLATE WHEN YOU KNOCK OR PRY IT OFF THE STOP. IT WILL BREAK YOUR ARM IF IT'S HIT.
DON'T ASK ME HOW I KNOW.
1½° is sufficient I would say 2° is the maximum negative camber that is practical.

NORM
 

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Lowering by adjusting spring plates - any experience?

#12 Post by Guest »

Dirk,
I have a table I developed to set the rear height at the
wheel center. One inch of height change is about 3.3 degrees
of swing arm change. If you just move it one tooth you will
be changing the angle by about 10 degrees which would mean a
change of 3 inches. To do smaller amounts of change you need
to change the inner teeth also. The torsion bar has
different number of teeth on each end. To change smaller
amounts you need to play the inner to outer teeth against
each other. This is the "vernier" effect. If you turn the
bar one inner tooth in one direction and then go the other
way on the outer teeth you will change the angle less that
on degree, about 3/4 of a degree. Remember to push up
slightly on the arm to remove any play in the system and you
want to try to have the left side 1/2 higher to compensate
for driver weight.

Alan

PS Good time to replace the bushings.

Dirk Heinrich wrote:
1 1/2" would actually do it. Does anyone know, how many notches on inner
or outer splines of the torsion bar that would be? I do realize that I
might have to combine some inner turns with outer turns to achieve that
- is there a list for the various lowering combinations.

Thx again,
Dirk


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Dirk




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Dirk Heinrich
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#13 Post by Dirk Heinrich »

Okay - I did it :D
And I am somewhat happy with the results. (pics are at the bottom of this post)

I had all the math down (I was going for 1.4 or 2.3 degrees, which would be 2 inner up and 2 outer down or 3/3), but it actually didn't matter and this is why:

The axle and the hub are always somewhat in the way - and this hinders the free movement of the radius arms. Particularly when you move the radius arm out, something is in the way.
I managed to get the torsion bar of the radius arm. This is when you realize that you can only count the notches on either the inner side or the outer side. I found it impossible to do two inner turns up with the radius arm on (keep in mind, it is an A - you cannot see the torsion bar with the radius arm on!). So I grabbed the torsion bar and turned it 2 notches, put the radius am back on and measured the difference in distance to the ground. PERFECT - 1 1/4" higher! BUT, in the next moment I realized that I turned the torsion bar the other way - down and not as intended up.
Hence, I actually have no idea what I did. I decided to try this set-up anyhow, did the other side and actually ended up with the car sitting 1 1/4" lower - pretty much what I wanted!

What did I learn:
- measuring the (difference of the) distances from the ground to the end of the radius arm gives an excellent idea of the amount of lowering. The calculation with degrees for my purpose is absolutely unnecessary - way to complicated and nobody seems to know how many degrees lower the car how many inches.

What needs to be done now:
- level the car (the driver side has been before lowering and still is 3/8 lower than the passenger side - it bugs me). This will be a challenge, because such a step requires more precision than what I did today.

Thx everyone for your interest!

Additional hints/help are always welcome.


Image


Image

P.S.: I am very tempted, but spare you all the pains I went through getting bolts off etc. ...

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Albert Tiedemann
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#14 Post by Albert Tiedemann »

All:

Please be reminded that any measurements and the medium used relate to a reference. This reference is most convenintly a level line, and one must be established by supporting the car in a safe fashion [jack stands and the like] when reaching the requiste position. Tweaking slightly with the jack can produce a "perfect bubble". A 24 inch houshold level on the cabin threshold has served me well for 45+ years.

Moreover, any excursion from the unloaded factory spring plate angle setting produces different toe in/out values. An increase in negative camber will produce more rear wheel toe in. An increase in negative camber and more toe in will wear the inside of the tire more. I am surprised that Mark has not experienced more tire wear since he does drive his car--a lot. The toe can be nulled out, but is best done on an alignment machine so that you can see the corrective effect interactively.

Regarding devices to measure the angle, the Factory tool works well and the divisons are less than the smallest correction possible [50 arc minutes] The latter is easily deduced from the number of splines 44 and 40 previously mentioned.

A protractor[big plastic one with a hole for the arc center {for fishing line}] and improvised plumb bob [nut on a piece of monofilament fishing line] can produce measurements to 1/2 degree-- which is still smaller than the minimum correction. I have used this method with success.

Or, you can get one of those fancy electronic spirit levels that can read to .01 degree. We are talking a real stretch to the ankles here. Spirit levels in this category were called "master levels" and used to level machinery to foundations. Shucks, no need to level the car that accurately because you can--so to speak--null the discrepency from level and read it direct. Or, if your pockets are not as deep, the economy version can be had that reads to at least .1 degree BUT you will have to compensate for any irregularities in the refernce line from level. Might be a difficult task without blueberries unless you write it down.

The Factory tool that Mark mentions is somewhat of an elegant device for the measurement given the time frame of its design and manufacture. It is also easy to use.
It embodies a magnet and a rotating "plumb bob" which relies on a spirit level to determine "plumb" or vertical. This tool is sensitive to reference level.

I think there would be very little call for this tool in your toolbox since most would opt for an improvised method. If you are interested in a clone of the Factory tool, drop me a pm.
Last edited by Albert Tiedemann on Sat Sep 13, 2008 11:00 am, edited 3 times in total.
Albert Tiedemann, C356C
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#15 Post by Albert Tiedemann »

1.4 or 2.3 degree correction is not possible as the smallest increment is 50 arc minutes.

Math 0 was a non credit course at the University of Maryland in the 50's.

Also, you do not have to see the torsion bar to make the correction. It is made by "feel".
The technique is to just pull the bar clear of the splines and rotate the bar in the direction of corrective action feeling the number of splines along the way by the transission of bumps felt through the bar. Hard to describe but easily experienced. It also helps to know when making the correction, which end of the bar has the 40 splines.

The hub and axles can be tied up out of the way. A husky tie stap over the upper shock mount should serve well. Cut when finished.
Albert Tiedemann, C356C
"The Hermit"

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