Hey Oldtimers! IRS Indexing Question

[DeMinimis]

Yea, I know, set trailing arms to 21-21.50 degrees relative to the level of the tunnel. However, I seem to recall, from years gone past, that you could set your trailing arms relative to the lower rear torsion cover bolt hole. Perhaps lower edge of the trailing arm lined up with the top edge of the hole, for example (or perhaps at the bottom, or maybe through the center of the hole, or...). Sure can't find any reference along those lines now. Am I off my nut, or does anyone remember this? If the latter, what was the guideline? Thanks!

[Ol'fogasaurus]

I seem to remember that myself but forget just what the locator is (I think it is a bolt hole) and just what the detail are. Did you do a search and/or there is a an old spiral bound book that I think has it. I'll check in a while to see if I brought it were I am currently. I use the protractor method myself as I wind the torsion bar a bit tighter.

I think this is what we remember:

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

"Offroad preload recommendations:

4-8° greater than stock
Swing axle
bottom edge of the spring plate is covering half of the bolt hole
IRS 70 on
the spring plate is even with the bottom of the bolt hole"

Lee

[DeMinimis]

Thanks Lee, perhaps the offroad setup is what I was remembering.

[Ol'fogasaurus]

I think the '70 and later s/b '69? The search was on a whim and I was surprised when I ran into this URL as the top line.

Lee

[sideshow]

I don’t have a copy in front of me but is that swing plate hole tip also in the? Jeff Hibbard "Baja Bugs and Buggies: How to book"?

I have always use the old method of eyeball it (And I actually own an angle finder), then adjust to fit. Vehicles are so different that math only gets you close

[Ol'fogasaurus]

I do have a copy of the John Muir book here and he only talks about the front torsion bars and mostly swing axle info. That is why I added the URL here.

Lee

[SCOTTRODS]

Everybody seems to like the books and references, but on the Bugs, you don't get many actual alignment options, so I always try to make sure I have a straight rear end (Adjustments holes in spring plates giving the only true adjustment of alignment), and then I set my car on level pavement, on slide plates (Couple of sheets of solid steel big enough to give some room on the contact patch) and jounce the car a couple of times to settle in. Then I look at the rear of the car while jacking it up to achieve a nice "stance" visually, looking for close to vertical, with no appreciable variance positive or negative... then I mark the placement of the spring plates at the best height and tear it all down and adjust the deviated amount of camber out of it... This works better with Swing axle cars than IRS, but I also give a little bit extra torsion on the IRS models to make up fro a softer spring... works a charm for me and never have alignment issues or tire wear issues in the rear. The cars always come out with a normal ride appearance as well.

[Ol'fogasaurus]

Remember on IRS cars there is a 20 degree axle angle max limit on stock bug CVs before is starts spitting the balls out.

After playing with torsion preloading I recommend a max of about 26 degrees before the bars stiffen up too much. I've gone as high as 30 degrees but again, that is pushing things maybe to the max.

Lee

[DeMinimis]

Thanks all. I have zero reason to think my Bug has ever been apart. My measurement came out to 22.50. 21.70 is reportedly the max. Plate lined up approx 3/16" above lower hole (eyeball). I set it up the same after replacing bushings, etc. Anyway, just curious.