Wishbone suspension bolt on kit

[ricola]

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

[Ross Morrison]

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.

[pure55vw]

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!

[Ross Morrison]

Where is the link to the gallery?

[Alex]

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

[ricola]

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

[Ross Morrison]

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.

[volkdent]

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

[Ross Morrison]

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.

[ricola]

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
Rich

[Ross Morrison]

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.

[volkdent]

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

[Ross Morrison]

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.

[volkdent]

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

[Ross Morrison]

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.