Need to reset torsions i the rear -5/8"

[Cornpanzer]

I want to lower the rear of my "S" approx 5/8 of an inch. Any guesses as to hom many splines or what combination I need to go with to achieve this? Thanks in advance.

[SprintStar]

Originally posted by Cornpanzer
I want to lower the rear of my "S" approx 5/8 of an inch. Any guesses as to hom many splines or what combination I need to go with to achieve this? Thanks in advance.

Are the splines 44 on one end and 40 on the other like VWs are? If so, I can try do the math for ya....

Merry Christmas!

Sprint.

[Cornpanzer]

Yes, they are 44 and 40. Thanks for any math you can help with Sprint. I was a better literature student than I was Math!

[SprintStar]

Originally posted by Cornpanzer
Yes, they are 44 and 40. Thanks for any math you can help with Sprint. I was a better literature student than I was Math!

Merry Christmas Corn!!!

I was never good with math either... But here goes. Haha...

The fundamental concept of the torsion bar adjustment (otherwise known as indexing) is knowing that a complete circle has 360° (duh!), imagine that each end of the torsion bar is actually 360° divided by the respective number of splines. The inner end has 40 splines therefore each spline is seperated by 9° (360 divided by 40) and the bar’s outer 44 splines are each seperated by 8 1/6° (360/44) or 8° and 10'.

Now, follow me on this... Imagine you squatting and facing the spring plate. If we fix the outer spring plate on the outer end of the torsion bar and then move the torsion bar inner by one spline (anti-clockwise - spring plate moves up and lowers the car), we will have changed the position of the spring plate relative to the ground by 9°.

Now if we fix the inner splines and now relocate the spring plate (clockwise - spring plate moves down and raises the car) we will be essentially removing 8° 10' from the 9° we advanced on the inner splines, thus resulting in a net 50' change in the spring plate position.

Due to the 4-spline difference between the inner and outer splines of the torsion bar, adding then subracting these relative angles allow us to adjust the ride height to within fractions of an inch.

Makes sense? Think about it, picture it in your head and reread the above till you get it.

Now, if you understand the above, you are ready to index your own torsion bars. Typically, if you are not changing the torsion bars you can ‘estimate’ the ride height change (approx 3/8" for a 50' change). So for 5/8" drop, you are looking at 2 splines up on the inner side and 2 splines down on the spring plate side. You move 18° up and 16° 20' down, with net 1° 40' (100' change).

Err... Am I confusing yet? Haha... If you can build a 12 sec VW (my dream), you can do this, Corn! Go for it!

Sprint.

[Cornpanzer]

Duuuuuuuhhhhhhhhh, yeah........what he said!!!!



Thanks Sprint, I may just tackle this on Fri. Or I may wait til good weather. Thanks for the tips, we will see how it goes.
BTW, dont tell anyone, but the Beetle is getting a Turbo. Here come the 10s!

[SprintStar]

Originally posted by Cornpanzer
Duuuuuuuhhhhhhhhh, yeah........what he said!!!!



Thanks Sprint, I may just tackle this on Fri. Or I may wait til good weather. Thanks for the tips, we will see how it goes.
BTW, dont tell anyone, but the Beetle is getting a Turbo. Here come the 10s!

Good luck on the indexing project! Hey, has the '70S got adjustable springplates yet? Since your stock plates are gonna come out, I recommend either getting some later plates with adjustment capability (like from the SC and later, if I recall right) or get the Sway-away ones....

This way, you set the height and can fine-tune it with the twist of a spanner!!! Would be terrible to have to remove and reindex just to get both side 100% right!

Hey, feed me more info about the Bug manz! I'm keen to turn my Super into a racer too.

Sprint.

[admin_old]

Great explanation by Sprint on the process.

For you less precise folks, here's another method:
Let's assume the rear end of the spring plate (close to the axle/CV joint) approximates the center line of the wheel/tire.

After unbolting the spring plate from the control arm and removing the bolts from the torsion bar cover, the spring plate is essentially free of any outside force. Measure and record the distance from the end of the still-installed spring plate to the ground. This is a starting reference point. Any TB adjustment upward from this reference point represents lowering the vehicle and any adjustment of the spring plate downward represents raising the vehicle.

Once the torsion bar is free from the inside and outside splines, one can adjust the relative position of both ends using the reference point established earlier. If you wish to go back to the original position, just reinstall the TB so the end of the spring plate is in the same reference location as you started.

Use Sprint's very accurate method (suggested) or the above method as a fairly accurate way to adjust the torsion bar. At any rate, having a starting reference point is a good idea in case you mess up or must complete the process at a later time/day.

Sherwood

[SprintStar]

Originally posted by admin
Great explanation by Sprint on the process.

For you less precise folks, here's another method:
Let's assume the rear end of the spring plate (close to the axle/CV joint) approximates the center line of the wheel/tire.

After unbolting the spring plate from the control arm and removing the bolts from the torsion bar cover, the spring plate is essentially free of any outside force. Measure and record the distance from the end of the still-installed spring plate to the ground. This is a starting reference point. Any TB adjustment upward from this reference point represents lowering the vehicle and any adjustment of the spring plate downward represents raising the vehicle.

Once the torsion bar is free from the inside and outside splines, one can adjust the relative position of both ends using the reference point established earlier. If you wish to go back to the original position, just reinstall the TB so the end of the spring plate is in the same reference location as you started.

Use Sprint's very accurate method (suggested) or the above method as a fairly accurate way to adjust the torsion bar. At any rate, having a starting reference point is a good idea in case you mess up or must complete the process at a later time/day.

Sherwood

Hello Sherwood,

Thanks for the compliments.

I'd like to add that a good way to reference the starting points will be to mark the torsion bar ends with white correction fluid that you can find stationery stores.

Hehe... I use it to mark everything! Even the pulley on my VWs to help find TDC while timing the engine!

Merry Christmas!

Sprint.

[NeunElf]

When I replaced rear bushings, I found that the torsion bars always pulled out when I pulled the spring plate off. Once that happens it's impossible to count the number of splines you're turning the inside of the torsion bar.

The factory shop manual instructs mechanics to measure the angle relative to the rocker panels. I think the stock set up in my 65 was something like 28 degrees. I got good results with a $10 plastic protractor-level from the local hardware store (identical to a picture in the Snap-On catalog).

Just in case you lose count of torsion bar splines, I would urge you to pick up a protractor-level and measure your starting point before you pull the torsion bars.

[admin_old]

"...to mark the torsion bar ends with white correction fluid."

This only works if you can see the ends of the bar. Once inserted into the chassis and with the spring plate splined, the TB ends are not visible.

Using an inclinometer helps establish the reference point as well; as does tracing the outline of the spring plate against the control arm. The angle of the spring plate relative to the door sill is a variable, dependent on the angle of the car on jack stands. Just record the angle of each spring plate as it hangs freely for a reference point. Use one of the previously mentioned methods to determine height change as a result of angle change.

Sherwood