Indexing rear end to gain ground clearance?

[Mike Sal]

Where can I find a detailed "how to" on re-indexing the rear end of my '70 bug chassis? I need to gain 1.5 inches (going from a 29 inch tire to a 26 inch & don't want to lose ground clearance). I'm new to working on vw (they aren't like my Studebakers) & would like to study up on it before making a mess out of things.

I've already found some Thing front spindles to take care of the front of the car.
thanks,
Mike Sal

[LeeVW]

Here's an excellent how-to article:

http://manxclub.com/Resources-Tech1.htm

This page shows you how to achieve specific amounts of lift or drop by turning the bars:

http://vw.zenseeker.net/Wheels-TorsionBars.htm

Lee

[Mike Sal]

Thanks for those links. They seem to be focused a little more on the swing axle style rather than the IRS. Can the same procedure be used without removing the swing arm?
thanks,
Mike S

[LeeVW]

Most likely, yes. I am able to do it on my buggy (Siggy Manx) by removing the shocks and the pivot bolts, then removing the bolts that hold the arm to the spring plate. I leave the brake lines and e-brake cables connected, but have the e-brake off. I also leave the axles connected. I am able to tie the arms up out of the way enough so that I can work on the spring plates. I know you said you have a '70 Bug chassis, but there might be even more room with that, so I say give it a try.

Lee

[Mike Sal]

Ok, I'll give it a try. The worst that can happen is the rig is stuck in the shop taking up space longer than I want.

I started to study the chart a little closer & have another dumb question. According to the chart, do I have to rotate the torque bar at both ends to acheive the 1.5 inches of lift I want (plus 7 notches on the inner & then 7 notches minus on the outer spring plate)? Or do they mean either or will get the results? I assume by moving the inner spline, they mean to leave the spring plate in the original location on the outer splines while counting inner splines??
thanks,
Mike S

[jsturtlebuggy]

While you have it apart you may want to think about using adjustable spring plates too. They really help with the final adjustments to making both sides come out even.
I have them on both of my buggies. The street buggy has the Chinese spring plates and using the smaller 21mm diameter 21 3/4in long torsion bars. The reason I went with the smaller shorter torsion bar was for tire clearance. I have been using this setup now for about 10 years now.
Using the longer 26 9/16 22mm torsion does give a more progressive (softer) but the shorter, smaller diameter bar is close to same spring rate.

On my other buggy I am using SwayAway spring plates. They are made stronger and since this buggy sees off roading a lot, I wanted something that I knew would hold up.
If you do decide to use adjustable spring plates they are wider across the face then the stock IRS spring plates. To get stock travel with them does require either notching both top and bottom of plates at were stock stops are case into the ends of torsion housing (shock tower area).

_________________
Joseph
Fair Oaks/Orangevale, CA
Elrod Motorsports
Motion Tire Motorsports
Having fun with Dune Buggies since 1970
Into Volkswagens since 1960

[LeeVW]

There are 40 splines on the inner end of each torsion bar and 44 splines on the outer end. This means a change of one inner spline will give you a more drastic increase or decrease in preload than a change of one outer spline. The chart has you use a combination of turning the inner spline one direction and the outer spline in another direction in order to achieve a net increase or decrease in preload.

So to get an increase in ride height of 1.5", you will need to turn the inner spline 7 notches in the direction you want to go and then turn the outer spline 7 notches in the other direction.

In checking my work, I looked at the description at the bottom of the chart in the link. It seems to be muddled up. It refers to "rear right side" and "left right side". Here's what you do:

For the left side (driver's side in the United States), carefully pull the torsion bar out of the center section without losing your place, turn it clockwise 7 notches, then slide it back in. Now remove the spring plate from the other end of the torsion bar without losing your place, turn it counter-clockwise 7 notches, then slide it back in.

For the right side (passenger's side in the United States), carefully pull the torsion bar out of the center section without losing your place, turn it counter-clockwise 7 notches, then slide it back in. Now remove the spring plate from the other end of the torsion bar without losing your place, turn it clockwise 7 notches, then slide it back in.

If you're replacing the spring plate bushings, you'll have to replace the inner bushings are some point during all of this, but at least this will tell you where things should go. If you have a protractor, you can check your work like this: After releasing tension and before doing any re-indexing, check to see what the angles of the spring plates are. It doesn't matter what the actual angle is, just write it down. When you're done re-indexing, you should see an increase of 5° 50' for each spring plate.

Make sure you mark the location of the spring plate in relation to the torsion housing after you've released the tension and before re-indexing so you can go back to the way it was in case something goes wrong.

Lee

[Mike Sal]

That makes sense. I was also a little confused in the way they wrote the description under the chart.

Was there a stock spring plate for IRS that used the short Torsion Bars? I'd like to use the shorter ones because they would look more accurate on my repro kubelwagen. I do like the idea that I can get the raised suspension without spending any money.

Those rubber bushings that the article said might be replaced.....where does the wear & tear come from? I would think with IRS there would be little movement on the bushings.
Mike S

[jsturtlebuggy]

You can take the 61-68 swing axle spring plates and cut them to the same length of the IRS plates.
It what I did years ago before SwayAway started making and selling them.
It a little work, but if you are creative you can use a hacksaw and drill to make them.
What I did was make a template out of cardboard (poster board) of the IRS plates and transferred the They are a little wider across the face (like the aftermarket ones) so modifying the stops or plate will still be needed to have full travel.
Also make sure to put anti-seize on torsion splines make it easier to take apart later.
Yes you may want to replace the rubber grommets (bushings) for the spring plates. Wolfsburg West sells good ones.
_________________
Joseph
Fair Oaks/Orangevale, CA
Elrod Motorsports
Motion Tire Motorsports
Having fun with Dune Buggies since 1970
Into Volkswagens since 1960