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Reply to "1969 IRS Question"

@ALB posted:

I did irs with short (swingaxle) torsion bars/end caps and found stock rubber bushings worked best.  The aftermarket red plastic bushings needed a lot of work for the end caps to fit properly and every time I put weight on the rear of the car they still squeaked, even when greased.  Stock bushings, lubricated with talcum powder is (I think) the way to go.  Gordon used some type of grease in his car but I found that the rubber just absorbed the grease (yes, Gordon, I used the same type), so went back to the talcum powder (which is, coincidentally, the factory procedure).

For spring plates I ended up taking some stock swingaxle units, cut them down to fit and liked how everything moved way better.  The aftermarket spring plates were just too stiff for good movement.  And if you're looking to fit the widest tire/rim possible, the adjustable plate takes up over ½" of room, and you know there's not much room for rear tires on these cars.  I know guys here say they like the ease of adjustability, but realistically, once most guys set rear ride height they'll never touch them again, SO WHY CARRY ALL THAT EXTRA WEIGHT (or pay for something that when you think about it, you don't really need)?  Doing it via indexing the torsion bars 3 or 4 times is more work, but once it's done, IT'S DONE!  And you're waaay faster at it by the time you're finished.

The 1967 911R style 7" Fuchs with 195/60's just fits with type 1 drums and stock trailing arms.  I took a pair of 15x6" Fuchs to a local wheel specialty shop and they added 1" to the inside.  Not a cheap way to go (Green's Automotive charged $500 for the pair) but it is what it is, I guess. I have some type 3 rear drum assemblies ready to go which will require narrowing the trailing arms.

The modified spring plates are also much lighter-

  • stock double irs spring plate- 2514 g.
  • Swayaway adjustable irs for 21¾" torsion bars- 2598, 2530 g.
  • stock single plate irs- 1779 g.
  • aftermarket irs with short (21¾) bars- 1776 g.
  • stock swing axle, cut down to fit- 996, 997 g. (a little more file work would have made them exactly the same but I was really bored by that point)

As well as having to be shortened, they need about 1/8" cut from both the top and bottom to match stock irs spring plate width (for full suspension movement).  Weight difference- 1602 g (3½ lbs.) PER SIDE!  And that's suspension (sprung?) weight- the only better weight reduction is rotational (wheels, tires and drums/rotors).

lightened spring plate- cut down for irs

Did you say Baby powder?

When Will that baby be finished

Last edited by IaM-Ray