Basics on the VW pans

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Ol'fogasaurus
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Joined: Tue Nov 14, 2006 1:17 am

Basics on the VW pans

Post by Ol'fogasaurus » Thu Feb 11, 2021 3:44 pm

Going through some of my old pix of the work I have done on two BJ pans I think I have some pix that I took during their builds might help others. Most have been posted but not together.
DSC00646.JPG
DSC00647 copy.jpg
DSC00648.JPG
These pix are close to about as basic as you can get but the front of the pan shown here is has a couple of additions... for the front suspension mostly.

The VW pan is a tunnel unibody design. Unlike other unibody designs the body is bolted on to the pan to complete the unibody function. The tunnel is made from an upper formed piece that goes from just in forward of the beam mount to the end where the transmission mount ends. The lower part of the tunnel matches the length of the upper tunnel front to rear.
IRS pivot 002.jpg
Implanted between the two halves in the rear is the torsion tube which is welded in place while the two halves of the tunnel are spot welded together. If you are going to be rough with what you are using the pan for then I would recommend welding the seams together to back up the spot welds.
pan and torsion tube support 03 (2).jpg
Pan and torsion tube support 02 (2) - Copy.jpg
The torsion tube has end supports that attach to the floors to help limit the potential twisting of the tunnel. The top photo shows the mounting on the top of the crosspiece of the floors and shows the lower hook. The bottom shows the lower hook which is known to break off under hard use.
Ball-joint to K&L frame head change-over 01.jpg
This shows the frontal addition for the mounting of the front beam.
001.JPG
The bottom of the pan showing the "beading" (forming) that helps the limiting of the twisting loading on the basic tunnel as well is the floors of the tunnel. Notice the "beading" of the lower part of the mounting of the front suspension which, again, helps stop some of the potential twisting of the front beam. Depending on your use of the pan additional support might be needed.
Ball-joint to K&L frame head change-over 02.jpg
I will add some more info later.

Lee
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V8Nate
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Re: Basics on the VW pans

Post by V8Nate » Thu Feb 11, 2021 5:45 pm

Very nice lee

Ol'fogasaurus
Posts: 16394
Joined: Tue Nov 14, 2006 1:17 am

Re: Basics on the VW pans

Post by Ol'fogasaurus » Thu Feb 11, 2021 6:00 pm

002.jpg
IRS trailing arm pivot mount.
DSC04948.JPG
DSC04949.JPG
The two pix show that the threaded part of the mount is probably a pressed in/interference fit way of doing thing and it part of the upper tunnel piece before the two tunnel pieces are spot welded together.

For what it is worth.

Lee
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Ol'fogasaurus
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Re: Basics on the VW pans

Post by Ol'fogasaurus » Thu Feb 18, 2021 11:59 am

One of the things I should have mentioned is that the two halves are spot welded together not seam welded. This means that the seams could be made stronger, especially the trans mount area, by seam welding them.

Lee

Ol'fogasaurus
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Re: Basics on the VW pans

Post by Ol'fogasaurus » Sun Feb 21, 2021 12:28 am

As I already posted the VW bug's front beam went from a King and Link setup to a Ball-joint the in '68 here in the "states" VW went from a swing axle to an Independent Rear-end Setup (IRS). Sometime in '71 as I remember the bug went from a double spring plate to a single spring plate. Because of what I think are other changes in the single vs. the double spring plate setup the connection fastener pattern was changed also so they single and double couldn't be interchanged (an old engineering trick)
Difference between single and double spring plate 001.JPG
On the left is the double spring plate 4 bolt setup with the trailing arm mount between the tow spring plates. The trailing arm mount on the right is the newer single spring plate with three holes.
doscpnnecting the trailing arm.jpg
This is the later single spring plate and trailing arm shown sans the fasteners.
spring notch 02.jpg
This shows the trailing arm's suspension stop on the torsion housing. In this case the trailing arm itself is notched to allow more suspension travel downwards. In this case the suspension has some weight on it so you can see what happens when the suspension drops and the amount of travel here is longer at the stub axles.
spring notch o1.jpg
This shows the notch with no weight on the suspension. There are two ways to make the notch: one where the notch matches the suspension notch with some gap at both ends to be sure that there is no dragging/wear on either the stop or the spring plate.

The other way is to make the forward cut on the spring plate then continue a line back to the radius of the spring plate.

Be sure in both cases to put radiuses in the notch to get rid of the potential of failure due to the square corner.
Unloading the torsion bar.jpg
There are a couple of ways to do this but this way is the safest. Do not reach under the spring plate or crawl under when you are either preloading or un-preloading as if there is a problem with things coming apart it is too quick for anyone to even see it. Hands, fingers, arm or heads can be broken in fractions of a second.
tools needed to set preload..jpg
Some of the tools used. I did a post years ago but the phots are now part of photobucket and not of good quality. The tool show has extra washers added as well as a nut that does the work. The handled nut that comes with the tool I used under the nut to stop any walking back off of the adjusting nut can do. The two washers make the clamping easier but make the backing off easier too.
setting the angle of preload 01.jpg
This is the preload angle before clamping back up and sliding the spring plate back into the torsion housing and back onto the stop. Before you start raising the spring plate up make sure it is very close but not under the stop on the torsion housing so the amount of side movement is negligible for safety sake.

The stock angle is 19° to 20° and this is set at ~26° for riding in the sand.

Lee
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Ol'fogasaurus
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Re: Basics on the VW pans

Post by Ol'fogasaurus » Sun Feb 21, 2021 12:31 am

Also remember that the inside splines of the torsion bar and the outside splines of the torsion bar are off-set so going back or forth on the two sets of spline adjustment can be finer than just one set of splines.

Lee

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