And the rack

Volkdebt, any progress on this over the break?

No progress as of yet Craig. I've got my Jetta up on blocks waiting for its tranny to return. I like to keep the M3 inside too, so I'm out of space till the Jetta is back together. I did buy a book on suspension design however, and have made a few more good contacts to work out the suspenion details.

Jason

Something to wet your appetites!
http://www.ricola.co.uk/wishbone_pics/wish_new_old.JPG
Progress is coming on nicely. Design work done, just the making now!

Rich

Just found this on the new volksrods forum:

http://server5.ipshosting.com/~volks...t=ST&f=2&t=479

Seriously nice :)

Cheers
Craig

Nice if you want Ford cortina brakes and the wheelbase extended by 6"...

Wishbone suspension design
 

Hello everyone.
Ricola, a double "A" arm suspension design using the stock VW steering is madness.
Why go to the trouble of designing something that you think will work, then try and use something that clearly WILL NOT work.
The whole front end should be designed as a unit.ALL the parts have to work in unison.
Think of the bump steer you are designing in.
There are certain "musts" as far as suspension systems are concerned, with w/bones the inboard mountings of ALL the moving parts(upper bones/lower bones/steering arms) MUST be aligned.
Look at the arc of the long arm on the VW box setup.
Look at the arc of the arms on the pic you have posted.
It should be obvious it won't work.

Sorry my first post is a negative one, but this is a serious mod that has to be thought out properly.

Cheers,Ross.

I noticed the stock steering as well and it could be a problem(hopefully that's just a "mock-up"). How about an idler-arm type steering (like early super-beetle)? You could gut an old steering box, attach your own pitman arm, mount the box on the other side of the tube, like the stock box, and connect them with a link that equal length tie rods would attach to. You could also adjust the linkage to get your Ackerman right. You'd also keep the stock steering shaft. I considered this on mine (see suspension pictures gallery), but decided to stick with R&P. Rest of the setup looks great!

Where is the link to the gallery?

Ross,

the gallery is on the main page.
Click the link at the bottom of every forum page www.germanlook.com and it will bring you to the main page.
On the left you will see all the different galleries.

Alex

Don't worry Ross, I don't plan on using the stock steering box. I was just evaluating how bad the bump steer would be but it is a no go. The ideal situation I was looking for was one which didn't need column mods. I don't know what you mean by 'aligned', but A arms should not be parallel on a road car for the best compromise.
I have found a steering rack of the perfect length now which will eliminate bump steer with proper location.
Starting with a blank sheet of paper and no front end would be the easy option, I want to develop a bolt-on module...
I was concentrating on getting the wishbone geometry correct first with the correct camber curve on CAD with a link model. For the steering it is easier to quickly mock it up than measure all the VW dimensions to the required accuracy and then model them.

Rich

Ricola, what I mean by aligned is, that if you were to draw an imaginary line through the top and bottom wishbone inner pivot points,(as viewed from the front),the pivot of the steering rack arms MUST be intersected by this line.
The other thing is.......why keep the front beam?
It is dead weight.I understand the need for a bolt on remedy, but if you are redesigning the front end ,you may as well do away with the factory parts and start from scratch.

Hey Ross!
 

Are you working on Martin's car? If your the man, we are glad to have you here. I'm copying you to a degree and just havn't got around to saying Hi yet. I've talked with Martin many times regarding what you guys are building. I have 86+ 928 spindles and a Golf II non-powered rack thus far, I was going to use the 65ET Cup II wheels, but its seems they are a rare item, so I'm going with the 52ET.

To comment on why keep some of the stock beam the Rich is using and keeping it bolt on, it means that someone can actually buy or build one of these things and simply bolt it onto their car. Not everyone has the facility or know-how you do, but they might have the cash, so they can buy a known quantity and bolt it on with little knowledge of what is involved in building a good suspension from scratch. I'd like to see what you came up with if you took this approach, as I'm sure it would be excellent.

While I'm writing, Martin said you used a Volvo top balljoint for the spindle, do you remember which model, or do you know of other balljoints that will fit into that top spot? I'm thinking about using a modified BMW M3 lower control arm on the bottom with the 928 lower ball joint, and then a very custom top arm with whatever balljoint will work.

I have to ask you, will you be reinforcing that front end on Martin's car? It looks pretty torsionally weak right now.

Jason

Hi Volkdent,
I have done some drawings on the "keeping the frame head" theory. It just wasn't happening. As you will be aware, the 928 upright has a very low mounted steering arm. To get any kind of decent steering arrangement in and around the tunnel part of the chassis was impossible.
I accept that using VW spindles means something could be made to work, but we weren't.........so I didn't!
If I was doing a "bolt-on " assembly, I would still lose the front axle.

Martins' front end still has alot of work to be done to it.
The box frame has to be tied into the cage, the shock supports are part of this, although I was looking into remotely mounting them and using bellcranks.
All the bracketry for the wishbone supports have to be closed
up,steering arms made,petrol tank mounts, inner wing mods, etc..etc...etc.
It will be worth it in the end.


p.s.........I think it was Volvo 340. I will check.

Ross.

Ross, I was trying to have a look at your site, (http://www.rmrrestorations.co.uk/) is it down at the moment? Would love to see progress on that rod with 928 V8 and your Ghia.
That's the advantage for the bug spindle with the high steering arm, although some 928 spindles had a bolt on arm which I would think could be modified although I didn't look into it in detail.
As for using the original centre section of the beam, for making a bug handle you would need some weight up front to get a bigger balance, making it lighter would just make things harder to tune! Picking up on points on the chassis which were designed to take these loads seems an obvious solution to me. Particularly in the case of my speedster, I need all the weight up front I can get, although I won't go as far as actually adding sand bags:D
Rich

Rich, yes the site is GONE!
Hard disc failure on the server or something. My mate is going to redo it when he comes up to Glasgow.

The 928 '34 Ford hasn't changed much. I have been concentrating on the Ghia and my new Chevy truck.

I will post pics of the Ghia as soon as I get the new bodyshell.(100% carbon fibre)

Ross.

Hey Ross,

I can't remember which year 928 spindles you used, but the ones I own have bolt on steering arms. With that in mind, I'm going to have new ones machined that have the pivot point way up high like the Bug ones so I can eliminate bump steerwhile having the rack over the top of the shifter tunnel. I suspect they will be quite expensive, but I do have a couple of master machinist friends that might be able to help me out. I know what you are talking about, using the stock 928 steering arms puts the steering rack right about dead square in the middle of the frame horn.

What kind of ETA do you imagine for finishing Martin's car anyway? How much did those rear bearing carriers cost to machine?

Cheers,

Jason

Volkdent,
Martin got a real bargain with those rear hubs.The guy quoted on the job without really looking at what was involved! I think it was about £50 each.($80)

ETA on his car? Mmmmmmmmm..............this year.:))

I considered unbolting the 928 arms and changing them, but be careful , there are Ackermann issues involved.Depends on which amendment to the principle you work to.
Another thing is to try and use a wheel with the same ET as factory.This helps with the KPI situation.

What rack are you using? How wide is it?


Cheers,Ross.

I'm using a non-powered Golf II rack that has a rack length of 21" so I suspect 22-23 balljoint to balljoint center.

Correct me if I'm wrong, but if the axis of the outer tie rod ball end stays in exactly the same axis as original, and the tie rod itself is relatively parallel to the control arms, and the inner ball joint on the rack has an axis that dissects the plane between the upper and lower control arm's inner pivot points, things should fall into place OK. I'm just theorizing here, because nothing I've read yet in suspension books deals with creating your own spindleIchanging the spindle steering arm pivot point).

What I have worried a little bit about is the brake caliper thickness causing me to make the new steering arm end pivot axis in a slightly different axis than the original. I don't know what that would do, and though I know moving it toward the the axle will increase my steering rate obviously, I don't know what other stuff will change.

Jason

Jason,
YES, having all the inboard pivot points co-axial is what you are aiming for to eliminate bumpsteer.
If you are going to fabricate new steering arms for the Porsche hubs, if you put them up high, then you use a wider rack.If you put them low then the rack can be narrower. This is because the axis of the pivots should narrow from top to bottom.
You are making the top arms shorter aren't you???
I would advise making all your arms in scale, or full size, in cardboard, then pin them to a board. Make a very accurate representation of the Porker upright, attach all the bits with pins, and then run it through it's full travel. You should be able to vary all the inner points and see what difference it makes to camber in bounce and droop.
You will notice the steering arms on the hub are very straight(fore and aft). Why don't you try and change them side to side?
We are using S2 arms and hubs.Are yours S4s?They are slightly different.Don't know if that is do-able.I will need to look at our hubs.
If they can be changed side to side,this will put the rack in front. You would then need to find a front steer rack, or get a RHD one and flip it.
With the arms being so straight,I don't think this would have any effect on the Ackermann.
I will look at Martins at the weekend and see if this is feasible.

Cheers,Ross.

Is there an advantage to front steering? I read in one of the suspension design books that front steer has some advantage when hitting a bump during cornering. It causes understeer for a split second rather than oversteer and makes the corner seem more comfortable. I could make the steering rack I have work as a front steer rack, but I had planned on rear steer. I had already thought about switching the steering arms, but there will be an increase in length if the same bolt holes are used, slowing down the turning rate, I presume. I will have new front steer arms built to have the correct length IF front steer is better, because it will involve getting a new front steer rack or making the other work backwards. If not, I think I'll stick with new rear steer arms moving the joint up high. Any thoughts you have would be greatly appreciated, as you have much more experience in this area than I.

Jason

Jason,
I was just throwing ideas around.
I have never read about those benefits of front steer.
Personally, I like the idea of the rack being behind any uprights, so as to offer some kind of protection in a smallish shunt. At least you could drive it home!
I would be interested to see the new arms you get made.

Cheers,Ross.

Update
 

www.geocities.com/volkdent/

Click on Conversion

Jason

I have to say, when I first read your idea of upgrading the front suspension I was intrigued but not interested, but I think I may just consider this swap over the next winter.

I currently have a IRS Balljoint pan, and may even upgrade the rear suspension as well If I can get it all to fit under the stock fenders ( I'm not opposed to cutting the body, Though I'd rather not)
and I'd even like to use the stock spindles


Volkdent
what is the rear suspension pictured on your site out of?

I'm halting on the 928 spindle, as it is causing me a little extra stress right now, but I'll come back to it later. I'm working with the stock BJ spindle right now, and maybe a lowered CB one later.

The rear end you are asking about is a 996 Turbo I believe.

Jason

I may just fab up some equal length A arms using my balljoint spindles, just to see how feasible it is

I've been considering pulling my pan off again and doing a bunch of work to it, but I may just grab another pan (I have a buddy with a VW wrecking yard, I can get a pan for nothing)

make all my mods to it and if it doesn't work out, well I still have my other pan.

Back At It
 

I finally recieved the Karmann Ghia front spindles with rotors drilled for Porsche. This should be an easier starting point. My suspension mentor, Bob Frostick-Stevenson, is back home too, so progress will hopefully continue now. I guess this is why my VW had been my hobby since I was 15! I'm 31 now!

Jason

How is this coming along?

It
 

Well, there came a certain someone in my life and she's a little more fun than ball joints! Speaking of which though, I finally just found the ones that will work. They are are from a Ford Granada and fit the KG spindle well. So no it's just a matter of taking the time to get all the measurements again then send the data off to Bob.

Jason

hmmm ford granada

been mulling it over, I've decided that the best way to develop a suspension is to just build one, or a couple.

I have access to conduit for cheap so I'm going to build a scale suspension and see how the geometry plays out. if I come up with a setup that I like, I'll go to full size, tack it all together and have a structural welder do the finish welding.

Hey shadowbug, don't use equal length arms as you wont get much camber change in roll.
If you shorten the top arm it will work better.

The idea is to use unequal length a arms, long as posstible on the bottom.

I'm looking into doing an AWD system so I'll need to use spindles from a front wheel drive vehicle (have been thinking VW golf)

Hey what are you gonna use for the AWD system? Are you gonna use a subaru setup? if not what system/

decided that it didn't make sence to build an entirely new chassis when the one I had was more than fine.

I've decided that I'm going to scratch build an entire car (what I've been thinking of doing for quite a while)

Using VW/Audi components

However I'm going to follow the example of one builder out there and build my front suspension so it cal be unbolted and pulled off in a single piece. Should I be happy with the setup I'll build a second one for the beetle. (was planning on staying within beetle dimentions anyway)

Just came upon this thread. What is the status of the conversion? Would be very interesting to see how the fit would be on a Ghia. Any news? will be even more interesting if one could use aftermarket spindles as well.




E

Because of the shifter shaft tunnel, it is necessary to have a spindle with steering arms that are high. The stock spindles have that, and with all the modifications in brakes you read about in these forums, its really not that bad an option to stick with.

As far as my progress is concerned, its slow as usual, but still making progress. Bob is working on calculations right now, though the measurments I feed him are suspect! Currently the setup I'm building uses stock KG spindles with Porsche drilled rotors, Ford Granada tie rod ends as the bottom ball joint, Volvo P1800 lower balljoints in the upper position, non-powered Golf II steering rack, Porsche 993 Cup II wheels. I've just purchased a wrecked Golf II that still runs for $100 for the parts that I'll use for the rear end. (See Audi S3 midmounted thread started by Bobtail)

Jason

very cool Jason! sure would love to see the pictures of the progress.



E

Have you gotten the a arms leangths settled yet? Are you gonna set it up with long rear arms (as long as possible) that are parellel to the ground. And upper arms that control camber changes? Gonna design in any ackerman steering? Any design updates or ideas would bo good to hear. Im kinda in the process of figuring out a double a-arm suspension so its nice to talk about design and whatnot with somebody that has more experience in the issue.

It's funny, I'm lying in bed thinking about emailing Bob in australia regarding the width of the track. I get online, and there's an email for me, telling me to check out the wishbone thread, and the question is arm length! I guess my ears were burning. So, the answer is no. There are a million variables that I'm kicking around in my mind. And a couple of projects, but it is getting close I'd say. Within the next month. Check in soon.

Jason

this is my debate.
the only reason for going with unequal length arms is for camber compensation,
if one was more interested a more fexible suspension set up than the paralel trailing arm suspension of the beetle, equal length A arms could be the ticket, and geometry would be much easier to figure out.

However thre are resources out there for scratch built suspensions like this. I've been frequenting the "Locost" forums for the last little while, and most of the information and design of these suspensions revolves around track cars and such. better handling means a lower time.

If I were to follow this logic through, I might as well srap my beetle and build a one off race car, because it'd be lighter, therefor better handling. Not really what I want to do, I'd rather have a beetle.

so here's the plan, I'll grab a pan from a buddy of mine (has half a dozen of them) and begin mocking up a front suspension, making use of a simple design and modern components. maybe I'll take a little more time to make it pretty, but strength first.


let you all know when I have some pictures to show you.