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Hello,

As I get tired of driving around with two 25kg marble bags in the front trunk, lowing plans existed as of day 1.

Lowering the spring perch seems like a nice and relatively simple idea, but that could limit the wheel width considerably, as the lower perch is just at the height of the top of most rim/tire combinations.

Next option is what I have seen on a german car once on a show at Budel (the Netherlands, Europe): BMW front springs of a E30 4-cylinder version.
That seems odd as the BMW has a front engine and subsequently probably moe weight on the front axle.
Well, only one way to find out, as nobody online seems to be able to have personal experience with them, so I bought a used set.

Spring coil diameter is actually virtually the same: 12,2mm !!
The spring is much shorter though and has exactly the same outer diameter as the standard 412 coil.
Here I put the bmw coil on an old 412 strut. This strut tower supposedly came from a 412 '74 model as well:



I still have to check if the top perch is not loose when all is bolted together, but sofar, so good.

Updates as time progresses

Regards,
Walter

As I will take the front strut apart and mount shorter springs, suspension travel will be less. So, it seemed like a good idea to also uprate the shocks to a more stiffer or more progressive shock.

Although the number on these new Koni adjustable shocks indicated that they were originally made for the '72/'73 model, the differences between thóse and the '74 model year shocks were small.
Koni supplied, cleverly enough, a simple spacer to make up the difference between the two, as can be seen in the next picture:



You also see the top bearing plate, which 3 asymmetric bolt holes measured (I have a '75 1303 as well) exactly like the '74 and later 1303 top bearing plate!! It would be very odd if the damn thing isn't exactly the same as the late 03 bug. After all, the 412 and the 1303 got that part in the same model year (1974)....

Here is the spacer on the Koni shock: its now exactly like the original '74 part hehe



Yes, I think this is going very well and that I got a little bit too scary by all the post I read before on 412 shocks and using bmw springs...
But I also realize that the proof of the pudding is in the eating and that part will have to come later.

With these pics, I at least hope to contribute to the information and experiences of the group.
Now I go and make me a tool to remove the large screw of the original strut/shock.

Walter

Wally,

Definitely keep the updates coming. It's great to see someone trying this. Who knows, maybe you'll come across for the recipe for a well thought out lowering procedure for the 411/412.

I'll be watching....

Tuna

Thanks Tom,

I have measured the front fender opening above the front tire to the ground after I remover the two 25kg bags out of the trunk and it is now 67 cm.
Thought I'd mention it here, so as I don't forget it and for future reference when the bmw springs are installed later (if everything works out and no major bolts break-off...)

Walter

The upper strut plate bearing and tube are very similar if not almost identical to the super beetle. But that is where similarity ends. The strut cartridge valving in the type 4 and the ball joint in the type 4 and the spring rate in the type 4 were much different.

It would not be out of teh question to have the BMW front springs be not far off. As I have noted a few times...teh front springs on the type 4....were way stronger than the car needed. They are more than you will ever need for even track work. They are also very progressive and very well proportioned. But...bear in mind...they are this way....to control the front end of the car when that massive trunk is full. So in that respect...its not much differnt than having a front engine....weight wise.

The issues with stock type 4 strut cartridges are many. The control level was poor for the vehicle. Though they are of higher rating than the super beetle......the balance of the valving was poor.

The audi 4000 cartridges are just superbly balanced for high performance for the type 4. But there will be some fitment issues to get around.

Lowering teh spring perch will not correctly lower the car...though that is what will be required to not have to much initial spring compression (possibly) with the BMW springs.
The spring travel and spring perch....does not govern the ride height. The internal stop of the strut cartridge governs teh strut ride height. Evenb if you are using non-self extending oil strut cartridges...and using a lowered spring perch and weight to keep the car at the correct lowered ride height....when you go over a bump......teh strut will over extend to its upper limit....unseating teh spring, causing massive rebound...and almost total loss of control. Be careful. The strut cartridge is what is important for lowering. The springs are marginally so. Ray

raygreenwood wrote:The upper strut plate bearing and tube are very similar if not almost identical to the super beetle. But that is where similarity ends.

Well, thats already more than I'd hoped for and the bearing and rubber inside that bearing plate are crucial to a rattle free ride and a light steering action.

It would not be out of teh question to have the BMW front springs be not far off. As I have noted a few times...teh front springs on the type 4....were way stronger than the car needed. They are more than you will ever need for even track work. They are also very progressive and very well proportioned. But...bear in mind...they are this way....to control the front end of the car when that massive trunk is full. So in that respect...its not much differnt than having a front engine....weight wise.

Good point Ray! and entirely my opinion as well.

Lowering teh spring perch will not correctly lower the car...

Still, that is exactly what the vw/porsche engineers did in 1973 when they made a 412 with the factory 2,0 ltr 914 engine in it (!)
There was even a 'Gute Fahrt' testreport of this car in 1973. Because of the lower spring perches (my guess), they did use 6Jx14 rims (with Kleber 185/70 VR tires, which were porsche like tires back in thise days.

though that is what will be required to not have to much initial spring compression (possibly) with the BMW springs.
The spring travel and spring perch....does not govern the ride height. The internal stop of the strut cartridge governs teh strut ride height. Evenb if you are using non-self extending oil strut cartridges...and using a lowered spring perch and weight to keep the car at the correct lowered ride height....when you go over a bump......teh strut will over extend to its upper limit....unseating teh spring, causing massive rebound...and almost total loss of control. Be careful. The strut cartridge is what is important for lowering. The springs are marginally so. Ray

I know your feelings on the above and I cannot quite follow you here and/or I may not agree fully with all of it, but thats ok, as your input is always greatly appreciated
After all, I will know in a few weeks if and how everything will work out or not.

Tnx,
Walter

Would TopLine (USA) or Kerscher (Europe) struts for the Super Beetle offer a solution for the 411/412?

No, wont fit at all; we discussed this many times

Wally, unlike a standard telescopic shock absorber...like on the rear of the 412, in ordeer to get the proper at rest height...the strut cartridge must be fully extended when the car is at rest and with average load. On the 412...and any "modern" strut based vehicle, there is very little or no compression of the actual strut cartridge while the weight of the vehicle is on the strut. This is because strut height at rest...is set by extended length of the strut cartridge at the end of its stop. This is also why the 411/12 has the nose high position. Its cartridges were too long. They were a design flaw from the start. The extra extension was made ...for the extra damping length from the longer stroke so that when the front end is fully loaded...it can handle the weight. The mis-calculation in this.....was that when you have afully loaded trunk and hit a dip at speed.....the enertia of that weight ...rebounds to far...extending the strut cartriidge to its former fully UNLOADED length. That is the main reason for loss of rebound ability in teh 30K mile range on stock dampers. The rebound damping was too soft and the rebound length too long. It damaged the upper seal on ALL of them.

Since the strut spring as assembled on the bench....has preload...it fully extends the cartridge. It 100% MUST do this. If you lower the perch releiving the springt of its factory set preload length.....when you go over a bump...and the coil spring compresses and then rebounds.....it will cause the strut cartridge to telescope upward further than there is preload for the spring. This will unseat the spring...causing it to land at an angle. That almost always snaps the spring....an causes extremely dangerous control loss of the vehicle. Good way to die.

Lowering the spring perch on a given spring...reduces preload. yes...that "might" lower the car...if there is enough weight to then compress that spring down. But...since at rest ride height is goverened by the full extended length of the strut cartridge...and not the spring compression level....that will mean that you have slack in the strut cartridge like I listed above.

If you want to lower....on ANY strut system....you MUST...go with a strut cartridge with a shorter fully extended length. The ideal is to go with a shorter cartridge ..then lower the perch to keep the preloaded compressed length of the spring on the assembled strut...the same as it was.
Yes...in order to not have the original spring have too much pre-load........which means you want to keep the original spring calibration by keeping it at its original length ...as measured bewteen bottom perch and top spring plate...then yes....you must lower the bottom spring perch as well.

I have examples of every production strut tube made for the 411/412. There were very slight differences through the years...but not in the measurement from the lower perch to the spring plate. There was no factory lowering.
If Porsche engineers experimented with lowering the spring perch...then what shorter cartridge did they use? Thats the inmportant part to know. If they did not lower teh perch...then they greatly increased teh preload pressure on the spring. This spring does well with that to about 1.5" or so...max. Then it starts breakinbg things. Been there..done that.
So then again...what new ball joints and radius arm mountings did they use along with the lowering of the spring perch and the shorter cartridge?

Also...its not just about swapping in a shorter cartridge. The valving of that cratridge must be useful. For instance.....an Audi 5000 cartridge can also be fitted with the use of a stub adapter just like the Audi 4000 cartridge. Thats the first one I tried.....just off the cuff...before I started actually cutting cartridges open in the junkyard and eelving into the valving and stroke lengths. Went through about 50 seperate cartridges this way. The Audi 5000 cartridge valving broke both a ball joint and cracked a control arm mointing point in the first week on opposite sides of the car. That was with only about 1" of extra preload on the stock spring.

The stock springs are huge...and stiff as hell..with a large amount of factory pre-load on them. Much more than the stock cartridge could handle. Ray

Whenever a spring pre-load is changed, or a spring rate is increased or decreased.....a corrsponding change MUST be made to valving...unless the spring rate change is being made to counter an existing problem in the strut cartridge valving. Ray

raygreenwood wrote: On the 412...and any "modern" strut based vehicle, there is very little or no compression of the actual strut cartridge while the weight of the vehicle is on the strut. This is because strut height at rest...is set by extended length of the strut cartridge at the end of its stop. This is also why the 411/12 has the nose high position.

This is the point where I think I humbely disagree:
Even when my model '74 412 is fully empty and low on gas, there is always some compression of the strut.
If not, then when I would lift the car with the car jack, lifting the car an inch, would immediately lift the wheel an inch of the ground...and it doesn't.

Its cartridges were too long. They were a design flaw from the start.

The long travel of the front suspension was done very purposely for comfort reasons (and it worked very well in that respect), or so I understand from the many road tests by german magazines in those days, which partly got their press release info from VW themselves.
This is quite well described in the book 'Die grossen VW' by H.G. Mayer-Stein, which is a book exclusively about the type 3 and 4.

The extra extension was made ...for the extra damping length from the longer stroke so that when the front end is fully loaded...it can handle the weight.

Yes, I also think that this was the case indeed.

The mis-calculation in this.....was that when you have afully loaded trunk and hit a dip at speed.....the enertia of that weight ...rebounds to far...extending the strut cartriidge to its former fully UNLOADED length. That is the main reason for loss of rebound ability in teh 30K mile range on stock dampers. The rebound damping was too soft and the rebound length too long.

Yes, I agree here as well and that is where the Koni shock comes in. Even in the most soft position, its already stiffer than the original vw shock with the oil in the strut. But that might also be just the age and subsequent aging of the original 35 year old fluid/oil.
Another proof of the oil being aged and now too thin is that the Koni schock should be equal in damping in its lowest setting as the original.

It damaged the upper seal on ALL of them.

Well, I just take a very good look at my original shock and its not damaged internally and still seals fine. Damping was also still there, but a little too soft.
So, instead of changing the valving by using another type of shock like the Audi one, you could also use a slightly thicker oil to fill the original shock with
I know you have tried this before Ray and never got the oil-type or the amount of fluid right I believe. I did this some years ago with a 1303 original vw shock and that worked very, very well. I believe we used a hydraulic oil.
Its just an option for those that don't have a Koni shock thats worth a try, since its almost cost-free and as we don't have that many option shock-wise.

Since the strut spring as assembled on the bench....has preload...it fully extends the cartridge. It 100% MUST do this.

Yes, I know and that will be my starting point.
Besides, its mandatory with our yearly (safety) inspection, so don't worry bout that

Lowering the spring perch on a given spring...reduces preload. yes...that "might" lower the car...

Not 'might', trust me, it does.

if there is enough weight to then compress that spring down. But...since at rest ride height is goverened by the full extended length of the strut cartridge...and not the spring compression level....that will mean that you have slack in the strut cartridge like I listed above.

As I mentioned before, thats where we disagree. There is a fair amount of compression of the spring at rest, so there is a fair amount of preload. The shorter spring will just lessen the preload, hence lower the car. It may not be that much, but lowering this way is really just using the margins that are there.
Its not rocket science, but we just have different perspectives of things I think.

If you want to lower....on ANY strut system....you MUST...go with a strut cartridge with a shorter fully extended length.

No, not MUST, but can.

The ideal is to go with a shorter cartridge ..then lower the perch to keep the preloaded compressed length of the spring on the assembled strut...the same as it was.

I fully agree here! That would be the ideal situation, but lack of shock options limits us in that way, as we all know too well.

Thinking out loud, IF you use a just too short a spring, you may even have to set the bottom perch a tad bit higher, as to not unseat it at full extention...

Using this method with a stiffer shock will lessen the chance of unseating the spring: The time necessary to go to full extension when the wheels come of the ground...(whats the chance of this happening when you won't go off-road driving...?) will be less, so the Koni helps here as well.

I have examples of every production strut tube made for the 411/412. There were very slight differences through the years...but not in the measurement from the lower perch to the spring plate. There was no factory lowering.

No, of course there is no factory lowering! I wrote that it was a factory test-vehicle with a 100 hp 914 engine. I assumed that made it clear that such a car has never been in production..(duh! )
I mentioned the article before: http://www.shoptalkforums.com/viewtopic.php?t=90482

If Porsche engineers experimented with lowering the spring perch...then what shorter cartridge did they use? Thats the inmportant part to know.

Well, the Gute Fahrt article didn't specify on that, as is to be expected from magazine articles in general as we all know too well. I already was pleased to learn what they did to lower that car back then in 1973!

If they did not lower teh perch

Yes, they did lower it. I tend too believe Gute Fahrt in that respect. Its a quality magazine, (still) sponsored by Volkswagen themselves...so the following is not relevant:

...then they greatly increased teh preload pressure on the spring. This spring does well with that to about 1.5" or so...max. Then it starts breakinbg things. Been there..done that.
So then again...what new ball joints and radius arm mountings did they use along with the lowering of the spring perch and the shorter cartridge?

Not really relevant as they did lower the perch; see the above.

The stock springs are huge...and stiff as hell..with a large amount of factory pre-load on them. Much more than the stock cartridge could handle. Ray

No, I don't agree here. I know you think this, but I believe that the american public has a different taste in what a stiff spring is, then we europeans in general do.
If I press on the front of my empty front trunk, it compresses SO easily (and I have the blue , latest, most stiff factory springs) . It is also very comfortable, but it would benefit from a little more spring for my tast AND a better shock.
With the bmw spring and Koni shock, I think I have both grounds covered.

Whenever a spring pre-load is changed, or a spring rate is increased or decreased.....a corrsponding change MUST be made to valving Ray

Yes, I really agree here, like said above here somewhere already

Thanks for taking the time Ray to inform this stubborn guy,
Walter[/url]

Wally, as I noted...there is little or no compression of the spring due to vehicle weight without load in the trunk. What I mean....by "little compression"....is relative. On a stock 411/412, you get about an inch max. Considering the stock, assembled uncompressed length is a bit over 18" for the measurement from perch to top plate.....that is a relatively small amount of compression. Adding 150lbs to the trunk...adds scant more compression. Maybe .75".

This is because....if you look at teh arcs of teh control arms...which are some of the longest on any strut vehicle I have ever seen.....it takes very little actual strut lowering to produce a significant angle change in the control arms...which equals physical clearance lowering at the subframe.....but only a little change at the wheel to tire clearance.

Add to that, the uncompressed length of the coil spring is about 3+ inches longer...when the strut is disassembled.

Before thinking that you can just drop the perch...anywhere up to 3+ inches....and still have tension on teh top plate...bear this in mind.
These springs are progressive. They have a load coil section at the bottom (for absorbing upward compression of road shock) and a control coil section at the top (for absorbing downward rebound and softening the arrestment of the chassis)

In order to arrest the chassis in the correct amount of stroke length...to keep from over rotating the pivot point of teh front control arms....you must have at least enough preload as was intended in teh design of the spring.

The stroke length of your 411/412 struts...is very very short. The 411/412 uses about 4-5" of the total rod length for its stroke. The strut rod is about 3 times longer than it needs to be.
If you simply drop teh perch..without using a shorter strut rod to both keep the original spring close to design preload......you will inadvertantly increase the amount of rod needed for the stroke.
This in itself is not a bad thing for the strut cartridge. It has plenty of capacity as you can see.

But.....you will very quickly cause the control arms to over rotate on teh down stroke. There is not much clearance at all between the control arms and the subframe. There is probably enough....but its risky. The real issue added to that...will also be the rotation of the factory sway bar....and also the rotation of the radius arms in their mountings at the rear of the subframe. They have a limited arc because of the angle on the ends. When it over rotates...it cracks the subframe socket. I ahve been there and done all of these things.
Just be careful of where you relieve preload in the progressive springs. Also...you will need stiffer damping for any spring relief or addition.

As far as the long dampers, struts and control arms being for comfort...I doubt it seriously.
The progressive coil...as noted.....arrests the dampers long before even 1/4 of the stroke is used. The struts were simply long because they had to reach too far. The car was designed to have the fuel tank in front. In order to suspend that tank in a way that worked with the front crumple zone technology the car was made with....and have it with teh shearable angled mountings it has....and still have a useful trunk worthy of the length of the front end, they were forced to have teh struts way outboard of where other dsigns would normally place them.
Add to this...the axial ball joint arrangment of strut directly atop teh joint (wheras most use an outboard clamp to locate the struts farther towards the vehicle center allowing more tire clearance)....and you are left with only one place to put the strut upper mount location. Up high.
Once you sling the spare tire well down low...you have pretty much.....will all of these allowances.....dictated that your strut must reach a long way in order to find its mount.
They made some of the same compromises on the superbeetle.

The only thing that actively prevents me from thinking this was designed this way for comfort.....rather than necessity....is teh length of teh control arms. The leverage generated by arms this length...is one of teh main sources of problems in the design. It is severely hard on the ball joints, control arm bushings and strut mounts.

It really does help to completely dissassemble and remove the front suspension...and carefully study the way the body is designed around it.

I agree with you that there is a great deal that can be done to the front end....and I have actually done most of those things. But what I am getting at...is that there is a limit without some pretty serious mods.
Some things you can greatly get away with for track use...wherin you plan to break things on a regular basis. But for long term driving and wear on the street...ether may be some issues. Ray

raygreenwood wrote:Wally, as I noted...there is little or no compression of the spring due to vehicle weight without load in the trunk. What I mean....by "little compression"....is relative. On a stock 411/412, you get about an inch max. Ray

Ah, but that means also that the (length of the) shock absorber does not govern the ride height, like you have previously mentioned!

Walter

Wally wrote: This is the point where I think I humbely disagree:
Even when my model '74 412 is fully empty and low on gas, there is always some compression of the strut.
If not, then when I would lift the car with the car jack, lifting the car an inch, would immediately lift the wheel an inch of the ground...and it doesn't.

This is one part I'm still not clear on either. My experience is just like Wally's- when I've jacked up any car I've owned, the wheel moves down and remains on the ground, while the body moves up some, before the wheel will finally come off the ground. This would seem to me that there is compression of the spring and strut when the car is sitting static. I would think that having no compression of the spring or strut at rest would result in a poor ride, as the car would want to sink into any holes. Also, hitting a steep driveway at 45 degrees might cause the two diagonally opposed wheels to come off of the ground (which I have seen happen in a radically lowered Golf before).

On the damper issue, I've seen it debated in forums before, and in the end, I believe conclusion was that the damper rod length and travel needed to be shorter, otherwise the damper is operating in a range that it was not designed for, possibly causing it to bottom out, or cause other damage. Then, the damper must be sufficient for the spring rate, otherwise, it cannot control the spring motion, causing a poor ride and increased wear/heat in the damper.

So, Wally, my theory (maybe flawed) is that you may have a damper that is of sufficient valving to control the spring movement, and keep itself from bottoming out given the lowered ride height, but it will have to be very stiff because it is very close to bottoming out just sitting still, since it is operating in the very last little bit of its intended stroke length with the lowered ride height. If one uses a damper designed to operate within a much shorter stroke length, and this is coordinated correctly with the resting position of the damper, the damping doesn't have to be as stiff because you are not so close to its bottoming-out point when the car is just sitting. These are the reasons, as I understand them, to change to different dampers when lowering. Am I making any sense?

To get an idea of what all extends when you lift teh car off teh ground...take a look at what is in the train of compression. A good 1.5-2.0 inches of stretch downward when lifting the car....comes from the earlystyle symettrical strut bushing it actually almost looks like it is turning inside out when it stretches downward from the strut and casting weight.

As I noted a couple months back...when talking about top stock damper seals and the flow of fluid diagram inside of the stock damper unit....you may get varying degrees of compression due to the condition of the springs, weight in the trunk...and how much compressed fluid is on the top side of teh piston...which bleeds down when sitting still...and lets the front actually rise slightly from the extension pressure of the spring.

But if you actually get out and start measuring the assembled spring length from perch to top plate..at rest...and at compression...you will not actually find that much compression at all.
Here..try something different....go out and remove the center nut on the strut without jacking up the car......when the nut finally comes off...does the car jump up when the spring unloads?....Not at all.

With just gas in the tank and the trunk empty.....no ballast...it sits still.

This is what I am getting at. The design of a strut spring does not require overly large levels of preload to be effective....and to be correct. The design of these springs for the weight of the front end ...in situ....is right on. It has some give ...as in compression...but that is also part of the flaw in teh 412 front end.
Instead of setting the car up to have a nose high attitude when empty...which also screws your castor angle up and aids in wandering.....they should have re-calibrated the spring to have level ride height....AND be more progressive up through the middle...so it then would still not droop when the front end was full.

That being noted as a flaw is one thing. On the other hand.....these springs are very progressive and at a very quick rate do they become progressively harder. As noted...the maximum stroke your suspension can achieve at the strut rod...is not much over 4-5". That means the maximum tension of that spring....is achieved in just 5" of compression . Thats pretty impressive for a spring whose overall length is over 20". It may seem like waste...but it is not.

In order to accomplish that in a shorter spring...they would have had to go to a thicker wire diameter. The light weight of the front end...would have then not had enough enertia to overcome the soft end of the coil on compression rebound. That wipes out strut bushings and does not allow damping to come on line....because the spring will not let the strut rod move very far. It also..can have so much rebound tension, that the overpressure inside of teh strut...wipes out the seals above the piston. By having poor rebound valving...this is what happened to stock struts...especially when a lot of weight (enertia) is in the trunk.

Wally actually has the right idea in going to a coil...that may have higher temper or very slightly larger wire diameter....as long as its progressiveness is in the right ranges. Gotta be careful. Suspension coils and all connecting componets are the most highly engineered and least forgiving parts of the car.

Modern coils...if you look at them closely....are not always of the same uniform wire diameter throughout.

They may actually have thinner wire at the bottom...in the tight load bearing coil range...but with closer spaced higher tempered coils. This means that the thinner bottom coils respond faster to small bumps...but with tighter coils...reach maximum load support quickly,before transfering load to teh looser coil at top. These same coils can have thicker higher energy wire near the top of the spring ...that is stronger than the finer wire but can bend and compress further before coil bind or maximum tension is achieved.

If you get more than an inch or so of compression of the strut rodwhen the front end is at rest on the type 4......you will not really have much problem with bottoming out. Unless you strut cartrdiges are just shot.....the coil springs at full bind are more than enough even with a full trunk (unless you are just carrying bricks or lead....or spare parts )

But what is teh problem....is that for instance...when hitting a speed bump...your strut which may be compressed from load or whatever...say 2" (which it should not be)...will then drop another 3"...as the strut compresses under load from contacting the speed bump.

Now listen close........that coil and damper...are absorbing this upward shock of the wheel and casting...by compressing...say...3". Bearing in mind that they are already compressed 2" (and should not be). What happens next...is that the coil spring unloads. Instead of just returning that 3" that they compressed.....and retruning the front end to the ride height it was at...when you contacted the speed bump...it will OVERTRAVEL...VIOLENTLY...to the full 5" of slack it has in the strut rod. There is not enough damping in MOST struts to fully contain this. You just have too much slack...and the damping is poor than it should be in the type 4.

This is the HALLMARK...of all type 4's (and I have drive nand owned a lot of them)....especially when the dampers have much over 30-50k on them.

By the way...this is exactly what happens when you lower by moving the bottom perch...but not shortening the strut rod as well. Thats what all of this is about. Its not about..."don't modify your front end"...its just about .....look at the design first. Ray

Ah, I think I'm getting it! But, isn't that what I always say?