IRS spring plates

Depends on your definition of "easy".

You still have to remove the old ones (I assume you've already read how to do that) and the new ones would be installed at the same un-loaded angle (the angle that the old ones were at when pulled off the lower stops and just resting before you pull them off the torsion bar).

If you install the new ones at the same angle as the old, it should get you dead center of the old car height, and then you can fine tune it with the new adjusters.

Plan on an afternoon to swap both sides......

Thanks Gordon, that's the information I was after...That the attachment geometry of double plates accepts a single plate replacement.  I did an 'SOC Search' and stumbled about the Internet without finding anything specific.

BTW, I'm not planning on doing such a swap. it's simply the information I wanted. To cut through some of the fog of technical ignorance that I'm faced with!!!  

I was going to convert my dual plate (1971) to adjustable - but decided the dual spring was superior to a single and all I'd gain would be side to side adjustability.  Then there was the multitude of sizes to pick from (I thought all springs were same size). I think the adjustable plates are a tad thicker than the stock spring.

You'd think it's a feature that would be useful (I have a set for mine that I'm taking off), but the reality is that once rear ride height on a street car is set you'll never play with the adjustment again. Carl, all you will have done is spent money you didn't need to, added extra weight to the car, and between the movement of the plates as the suspension loads/unloads and the squeak of the grommets they're noisier, so for most guys I don't think there's anything to be gained here. If you spend the time getting it right (may take 2 or 3 trys) with the stock parts you'll save yourself some money, not be adding weight and the car will be quieter as well. I believe the procedure is to dust the rubber grommets with talcum powder during assembly. A magnetic protractor is what's needed to get both angles (and the resultant ride height) the same.

A couple things you have to watch out for, guys- the torsion bars are twisted enough that when you pry the spring plate off the ledge it sits on it will drop with enough force to break your leg, if it's in the way, so be really careful of how you position yourself. Also, I believe you have to use urethane grommets, as the diameter of the part (do we call it a collar?) that goes around the torsion bar splines is larger, and I'm told that no matter how well you grease them, they squeak. Al

I agree with Al.

I use CV joint grease in the grommets (rubber or urethane) and they don't seem to squeak anywhere near as much for years.

The dual-plate rear was used (IIRC) on the VW sedan in the second half of 1968 and most of 1969 - that's it.  It is identical to the spring plates used on the 914(?), 924 and 944 for those years, too.  They are RUGGED for our application, to say the least.  If it were mine (just like Pearl), I would use the dual plate set-up and take the time to get it set right.  It took me three tries over a couple of years to get it where I wanted it.  Adjusting them is NOT that hard, leg-breaking aside.  Using the method I published, you can get it rigt the first time without angle indicator tools.

I think I also tell you to jack up the spring plate(s) with a floor jack, pry them off the stop and then let them down with the floor jack to make everything happen in slo-motion and minimize the risk of the plates taking out your leg.  Seems to work for me.

According to VW 'spurts: Double spring plates were used on 68 Auto sticks, and 69-70 Type 1s. (Later part '71 went back to single) They were also used on all Type 3s. Type 3 kept them. Ghias used too.

Both my '71 pan CMC and Dolphin beach buggy (both '70 production dates) have the OEM dual springs.  Apparently the duals are individually softer than single but don't twist sideways as much.

I was of the understanding, Gordon, that any type of grease attacked rubber spring plate grommets; maybe that was just an issue with the original VW ones and the present aftermarket replacements (and their different composition) don't break down like they used to? That's why I had mentioned using talcum powder. If you can grease them, all the better, as they then won't wear a groove into the plate over time (I think).

Greg has a typo in his post above (I think)- the torsion bars come in different thicknesses from Sway-away, and can be used to advantage in a lowered car. Later swing axle bugs (1960 on?) used 21mm bars (I think) and irs cars came with 22mm bars (again, reaching deeeeeep into the ancient memory banks here, so anyone please feel free to correct me if I'm wrong) which is right for stock height cars, but when the rear is lowered an inch or 2 they are now too soft, the suspension bottoms out more, stiffer shocks are added and then the ride just becomes rough. I know this from experience with a Cal Look bug.

Adding slightly heavier diameter bars to a lowered car is the right way to do it; you're starting with less tension on them and as these cars are the same or a little lighter than a stock bug, the spring rate at rest is close to stock so 1 or 2mm heavier bars are just about perfect for most guys. If building a car to slalom, then you may want to step up another mm or 2, but I think they would be a little too stiff for a car that spends all it's time on the street. IIrc, Intermeccanica uses 24mm rear bars in it's type 1 powered cars. I don't know what they do with the Subie or 911 engined cars.

If you have the later irs single spring plates, I wouldn't rush out and try to round up the earlier double pate pieces, as the single units are more than enough for the suspension travel these cars have, and they're lighter too. No need to add weight where it's not needed. Also, remember that irs torsion bars are longer (about 3"?) than swing axle bars, and parts can not be randomly intermixed. You can use the shorter swing axle torsion bars on an irs car (makes resetting ride height way easier), but instead of the longer nosed irs spring plates you have to either cut down some swing axle plates or buy them aftermarket, and use swing axle end caps.

914 had rear coil springs, but in the front had the 911 torsion bar suspension.

Setting ride height is all good and fine, but to properly corner balance a car, adjustable spring plates are required as are a set of scales. The problem is the front torsion leaves, as they are not adjustable from side to side. But this is why it is so important to use scales on all four wheels and get the corner weights as close as possible by adjusting the rear.

I believe I've stated this before, but let's say the left fender is 1/4" low and the right fender is 1/4" high. Then you have 1/2" of actual crookedness built in to your "ride height" even though it "looks" fine. You'd actually be better off measuring from the suspension pickup points to the ground, NOT the body. Because we all know how perfectly straight our replica bodies are, don't we?

And just because you match the spring plate angles left and right doesn't mean the same actual weight is on each corner. But the same weight and matched alignment settings makes a tremendous difference in handling. If the car does the same thing when turning left or right, it makes the car predictable, which makes you faster. But not only faster, safer. Safer is good, especially in an emergency/avoidance situation.

I have corner-balanced a few cars, and it is pretty apparent the difference it makes.

Of course, if you are a boulevard cruiser, all this is academic and not important. But me, I like to push it right to the edge(on the track anyway). I don't think anyone has pushed my car as hard as I have(maybe Carey?) but if they want to take a spin, they will be able to feel that "balance" even with the archaic suspension.

Good stuff Danny; as you say, not that important for most guys in street cars, but if you want the most out of it, corner balancing is the next step.

Whew!...

This is what happens sometimes when asking what initially seems a simple question. It results in information overload!

"Corner balancing. Torsion bar diameters. Height measurement within a fraction of an inch. Lubricating properties. Potential broken legs...etc, etc."

Almost makes me envy those whose passion is Miatas!

Scales should be used ... but a lot of shops do not have them and they will try to fix you up by moving the adjuster on the torsion bar portion of the 911 suspension then your off balance with weight distribution... even is camber and toe in is ok. Ray

Ha, Miata's are just as complicated and have same MADNESS.  I'm contemplating a 2016 Miata when they come out in early Sep.  They have a gun metal grey with rust top and interior.  Club version has LSD and Bilstein shocks --- even Brembo calipers are (costly since bundled with BBS wheels) option.

Carl....One last thing:

If you go from a '69-ish dual spring plate to a single, adjustable plate, you'll also have to get a '66-'67-ish (or '71 and later), rear, swing-arm, torsion bar end cover from a sedan.  The dual plate end cover is deeper where it fits over the spring plates to accommodate the two plates.  Going to the earlier, single plate style needs a shallower end cap and it's corresponding rubber/urethane bushings and four mounting bolts (which are shorter).

(and you thought this was a cakewalk, didn't you?) 

And, yes.....the proper way to set up one's suspension is with a set of corner scales and yes, doing it with adjustable rear plates takes minutes, rather than hours with regular plates, but most of us on here are not racing these eggshell cars and only want to set them up so they look good (i.e.; all fender corners look "balanced" when looking from a short distance) once, and then drive it like that (whatever "that" is...) forever.

It only seems intimidating if you've never done it the first time.  After that, no big deal.

Ah so the torsion bar is different length swing vs IRS and that determines which spring plate to get.

I like the new NDs too. Metal grey club version would also be my choice.

The distance from the torsion bar to where they bolt to the axle tube or trailing arm is different as well.