1969 IRS Question

Both washers at pivot appear in correct location..

spring plate should be mounted inboard of the trailing arm mount..

Thank you for the reply @Wrenn Smith. Next question. I have tried mounting on the inside of the trailing arms, and it still seems to distort the spring plate, now towards the inside. It does allow the cover to be bolted in place, but it seems that the spring plate runs dead center to the trailing arm bracket. I know that I am overthinking this.

Thanks again!

Hi @Eric N.  I know it looks that way.  Once you get the bolts in the cap really snug, you should see less distortion in spring plate.  Also the slotted holes are part of the rear alignment adjustment.  The plate is spring steel and has to flex with the trailing arm angle change during suspension travel.  Hope that helps

The reason the springplate doesn’t seem to go in far enough is because of those urethane bushings. They are notoriously ill fitting and squeaky in operation. I’d opt to use stock style rubber bushings instead. If you want to stay with the urethane, you can massage them a little to fit better.

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).

Al, that 996 gram weight is with all the holes drilled?

@LI-Rick posted:

Al, that 996 gram weight is with all the holes drilled?

Yes Rick- that's as it sits (it may be before paint).  I look at that pic and think a little more could be taken off the top and bottom, there's room for a few more small holes and you'd get another 30? 40? 50 or maybe even 60 grams, but they're on the car and I'm finished with them.

I believe this is off of an aluminum bodied Spyder re-creation-

@LI-Rick posted:

Al, that 996 gram weight is with all the holes drilled?

easier just go to Taco Bell for the chefs special

Some of the 1969 (only) beetle suspensions had dual spring plates in the rear, so they fit on each side of the big forward facing tab on the wheel hub on the diagonal arm.  That is the same rear suspension as on a Porsche 924.  I'm pretty sure that the rear disk brakes are bolt-on (but mega-buck$$$, too).  You can see photos of mine (it has the dual plates per side) in the article I wrote on setting rear ride height, here:

https://www.speedsterowners.co...rear-ride-height--vw

On that version, the rear toe-in is set by moving the hub forward or back or, if really out, with wedges (or thin washers) between the plates and the hub casting to push the hub slightly to get it aligned, which is much harder to do with the dual plates.  The purpose of the dual plates is to prevent any toe in/out flexing in hard cornering.  It works great.

I don't know if this was a standard thing on '69 VW sedans or some sort of factory/dealer option, but there weren't a whole lot of them out there.

Thank you everyone, for all of the great information.!

I guess, I was hoping that the spring plate mounted on the outside of the trailing arm tab. This would make adjustments to the ride height a lot easier, since I cannot seem to tuck the plate behind the tab, without partially removing the trailing arm,

Just to throw a wrench in the stock VW bushing love-in...

The stock bushings on my car broke down within 5 years, and created a nice squeak any time time the spring plate moved. I put Saco yellow prothane bushings in it and everything started working better.

I think they've been there for 10+ years.

Also - I'm a fan of reducing unsprung weight as much as the next guy - but there's no way I'm doing anything at all to reduce the strength of the rear suspension in side-loaded situations. Al's pictures scare me, and I'm not usually scared of much. I've got the double wall spring plates. There are times when too much is just right.

I gotta agree with Stan’s last comment.  Those drilled out spring plates look sketchy to me.

The thing is, on IRS, there isn't a whole lot of side-load on the spring plates. Fore and aft, yes. Up and down rotation yes. The trailing arm, torsion tube, and spring plate make a pretty stiff triangle. Even with the holy spring plate.

Well if it's "holy" instead of holey then you're bound to be well protected, right?

@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).

Did you say Baby powder?

When Will that baby be finished

I have a '69 pan under Bridget the Midget and it's got the dual spring plates. I believe it was a one year only thing. Is it possible that the way it's made is ever so slightly different from all other year VWs, such that the trailing arms won't properly swap and therefore the modded, narrowed ones won't either?

Asking for myself...as I'm going to be getting under that car in the near future and was thinking a set of narrowed arms might be just the ticket.

@edsnova posted:

I have a '69 pan under Bridget the Midget and it's got the dual spring plates. I believe it was a one year only thing. Is it possible that the way it's made is ever so slightly different from all other year VWs, such that the trailing arms won't properly swap and therefore the modded, narrowed ones won't either?

Asking for myself...as I'm going to be getting under that car in the near future and was thinking a set of narrowed arms might be just the ticket.

I believe the trailing arms are the same, Ed

Me, too.

And you know…….    Those dual spring plates per side in a 1969 VW?   While they certainly weigh more, they work with the triangulated diagonal arm to keep the rear wheels so true and corner so much better that I don’t begrudge the added weight.  It’s the same set up used on both the 924 and 944.  It’s like having a stealth 924 under your VW Sedan!  (Without the bigger engine).

@Gordon Nichols posted:

Me, too.

And you know…….    Those dual spring plates per side in a 1969 VW?   While they certainly weigh more, they work with the triangulated diagonal arm to keep the rear wheels so true and corner so much better that I don’t begrudge the added weight.  It’s the same set up used on both the 924 and 944.  It’s like having a stealth 924 under your VW Sedan!  (Without the bigger engine).

I believe this to be true as well. Of all the places to save weight, I'm not inclined to do it here.

@Gordon Nichols posted:

Me, too.

And you know…….    Those dual spring plates per side in a 1969 VW?   While they certainly weigh more, they work with the triangulated diagonal arm to keep the rear wheels so true and corner so much better that I don’t begrudge the added weight.  It’s the same set up used on both the 924 and 944.  It’s like having a stealth 924 under your VW Sedan!  (Without the bigger engine).

Should I be looking for the dual plates, for my 69?

@Gordon Nichols posted:

Me, too.

And you know…….    Those dual spring plates per side in a 1969 VW?   While they certainly weigh more, they work with the triangulated diagonal arm to keep the rear wheels so true and corner so much better that I don’t begrudge the added weight.  It’s the same set up used on both the 924 and 944.  It’s like having a stealth 924 under your VW Sedan!  (Without the bigger engine).

@Stan Galat posted:

I believe this to be true as well. Of all the places to save weight, I'm not inclined to do it here.

You (and Stan) are over-reacting.  I (nor anyone else I know) has ever seen a folded or twisted single spring plate from normal or even extremely spirited driving on a well prepared street bug.  There's a reason VW went from the double to the single irs spring plate- in a less than 2,000 lb. car it simply wasn't needed.  In cars like the 924 and 944, which outweigh even a late model Beetle by more than 1,000 pounds, I get it, but a 1600? 1700? or even 1800 lb. Speedster? I don't think so.  How many irs Beetles with sway bars, better shocks and wider tire/wheel combos have been running around with single spring plates over the years- have you ever heard of anyone that's destroyed a spring plate?  I haven't, and you won't find anyone on the Samba, or any of the other VW forums talking about it BECAUSE IT DOESN'T HAPPEN!  When you can come up with data to support that statement I'll be the first to admit I'm wrong and believe you, but until then admit that it's only an unsubstantiated opinion and stop spreading such B.S. as gospel.

@Eric N posted:

Should I be looking for the dual plates, for my 69?

No you shouldn't- your car doesn't need them.

Al - I'm OK with you doing you, buddy. I'm happy with what I've got.

Have a great night!

@ALB wrote: "You (and Stan) are over-reacting."

Of course we're over-reacting.   That's what we do!

And Mr. @ALB - You can run a single spring plate if you wish.  More power to ya.

I'll still run two.   'Cuz two is bettah than one!

@Gordon Nichols wrote- "While they certainly weigh more, they work with the triangulated diagonal arm to keep the rear wheels so true and corner so much better"

You can believe anything you want, Gordon, and if running the dual plate spring plates makes you happy, go for it.  I understand you may believe it, but you're putting out what's purely your opinion as fact when you have no information to support it.  While I admit that most of what I know about this is anecdotal and/or 2nd hand, I have done the reading and asked the questions and I do have some first hand experience as well.  I did some parking lot slaloming (autocross) way back in my early 20's and the single vs double sp was a topic amongst the VW guys even then (didn't think much of it at the time as my '72 bug was a Canadian Standard with swingaxle), with no clear winner on either side (driver skill really seemed to be the bigger factor).  Yesterday morning I searched the Samba forums for "broken spring plate", "bent spring plate" and even just "spring plate", didn't find 1 instance of anyone talking about this and even searched the gallery using those search words.  You'd think that if someone had folded a spring plate there'd be a pic, but I looked through page after page (and there were a lot of them!) and not 1 hit.

Sooo,,,, I hope you can see where I'm coming from.

If not

In the present circumstances you can't take too many chances...

@ALB posted:

... I did some parking lot slaloming (autocross) way back in my early 20's and the single vs double sp was a topic amongst the VW guys even then (didn't think much of it at the time as my '72 bug was a Canadian Standard with swingaxle), with no clear winner on either side (driver skill really seemed to be the bigger factor).

Ah. I think I understand now.

You're usually such a congenial guy, Al, that I was kind of wondering the other day what had happened. I thought maybe a double swing-plate had harmed you in some way, during your formative years. Perhaps one laughed at you in the Jr. High locker room, or stole your high-school sweetheart. Whatever it was, it had to be bad.

But now I see that this was a debate back in the day, among people who cared about such things - and that like "Ginger vs. Maryanne" or "Ford vs. Chevy" or "edge piece of the brownie-pan vs. middle-piece of the brownie-pan", strong opinions were developed in adolescence which solidified into an immovable concrete fortress in adulthood. Ginger was a hussy. Chevys are just better. The edge pieces are always tastier.

You and your posse were confirmed single-plate guys. The double-plate guys can all go pound rocks.

I've got no such background opinion, as I came to this ridiculous hobby a bit later in life. But I've always been of the persuasion that more is just more. If I were designing something (say, a house or an engine), I'd be inclined to overdo it - not that I've ever gone too far or anything.

I was curious about this since you expressed such strong feelings, however, and so also did some reading.

Your summary of the state of the world is correct. VW did go to the double swing-plate, then back off to the single, although "why" is not something a giant company (and especially a giant GERMAN company, who's engineers are, after all, infallible) ever really talk about.

Maybe they figured they didn't need it on a car running skinny little bias ply tires, drum brakes, and a leaf-blower engine. Maybe they were trying to save .50 Deutschmark on every "unit". Maybe the double swing-plate was an extravagance that made it through to production before the entire swing-plate engineering department was fired for wasting company resources. Maybe a double swing-plate made fun of the VW CEO in the Jr. High locker room, and he could not abide one in his company.

We'll just never know.

All I know is that I'm a more is more guy, and would have a hard time making a critical part of the car weaker, since I've already got the double plates. I know this is unsprung weight (at least 50% of it is), and I know that almost everybody thinks they're fine with singles, and I know that they aren't folding in half all over the world.

If I were building a car, I'd have to think harder about this. As I already have what I have, and as I fling my car about in the mountains like I'm not ever going to die and I've never had even a hint of deflection in the back end - I'm sticking

... but again, the opinion wasn't formed when my brain was still malleable, so I've got no skin in the game.

I'll be over here, pounding rocks with my double swing-plates.

You do you.

Maybe these opinions('cause that's what they are) were formed back when good gas, low-compression, and semi-hemi(a BS term if I ever heard one) heads were the thing.

A single spring plate is about 1/4" thick, right? And it is loaded in tension and compression longitudinally(fore and aft). Spring tension/suspension bump action is up and down on the edge. The singles are certainly vertically stiff enough.

The thing I may be missing here is THERE IS NO SIDE LOAD on the plates. There is simply no need to double up the plates on a car that is already lighter than the plate was designed for. I'm not a weight-weanie hole-driller like Al, but I don't like extra weight for no reason. And there's just no reason.

I've got zero skin in this game either. I arrived here on SOC even after my friend Stan. I don't nor will I ever own a torsion-bar-equipped clown car. I've got tubular trailing arms(light AND stiff) and coilovers. Side load is taken by the swing-axle tubes, or the TRAILING ARM DIAGONAL for you IRS guys.

Oh no, the heresy...

Yeah….  ^^What @Stan Galat said!^^    😉

I don’t honestly car what anyone else is running back there.  I got beat a few times at Autocross in the ‘70’s by a dune buggy on a ‘69 pan and figured that must be part of the “secret sauce” of the winner (or maybe he was just a better driver or had a better engine, I don’t know).  When I had the chance to buy a ‘69 pan for my car I jumped on it.  It corners as well as a Porsche Carrera, at least at Roebling Road track, so I’m happy with it.  

By the same token, I’m happy to see you do you, with whatever car/engine/suspension you want.  I don’t criticize, and if I see something really out of whack I’ll try to suggest improvements - This isn’t that.  One spring plate or two?  For 99.9999% of the drivers out there driving to/from ice cream or some back road twisties, it won’t make a difference.

Now, I’ve got to get back to removing another mouse nest from my Rogue’s heater blower……..    🤬

Um...  So what oil should we use?

You're a funny guy, @Stan Galat!  As I said, when I was first exposed to this discussion (all those years ago) I was running a swingaxle car so it was really of no consequence to me.  I really didn't pay THAT much attention to it at the time.  Sorry to disappoint you, but it's a simple thing- what was originally said (in this discussion) was an opinion and should be expressed as just that- an opinion.  It's a fine point, I know.  What a guy builds his car with is his business-you choose 1 way to get something done and I choose another.  We both end up in the same place and respect the other's choices and yes, there's room for us all under the tent.  My point is that people read what we write here and use it as a resource, so the information we put down should be accurate.  Eric N's question right after the initial exchange- "Should I be looking for the dual plates, for my 69?" illustrates my point- according to what was said you'd think there's a clear benefit and it's really the only way to go, but it's not that black and white at all.  That's all I'm saying.

Enjoy the day! (you and your double spring plates)

PS- send 'em to me and I'll drill some holes in them for you...                                        you'll have strength AND light weight!

I dunno, look how well crazy ideas like @ALB's worked out for Colin Chapman. He's dead now, is that just a coincidence?

@Lane Anderson posted:

Um...  So what oil should we use?

Olive. Unless you're using high heat, then we like avocado.

@Michael Pickett posted:

I dunno, look how well crazy ideas like @ALB's worked out for Colin Chapman. He's dead now, is that just a coincidence?

I'm not sure how to react to that...

Just teasing our friends who see danger behind every door or hole 🙂

@Michael Pickett posted:

I dunno, look how well crazy ideas like @ALB's worked out for Colin Chapman. He's dead now, is that just a coincidence?

Is he?

The only people to see his body were his wife and the doctor who signed his death certificate.

Oh now that is very interesting.

@Stan Galat posted:

Is he?

The only people to see his body were his wife and the doctor who signed his death certificate.

That's because someone had drilled holes in it.

@Michael Pickett posted:

That's because someone had drilled holes in it.

I was 26- I hadn't started yet!  _{(wait- I did own a drill...)}

@Stan Galat posted:

Olive. Unless you're using high heat, then we like avocado.

Grapeseed my friend.