Lower Ball Joint Extension / Re-positioning

[24V Renshaw 0]

Since driving the Standard VR6 at standard ride height and enjoying the handling so much, as VW intended and everyone still raves about, I have decided on the new Corrado Project that I will lower the car, but want to then straighten all the wishbones and track rods back to their original angles to maintain the roll centre.

As I am well aware this is not as straight-forward to do as on a MK2 Golf or 16v Corrado as the ball joint bolts through the hub, rather than being a pinch type.

 

I know you can buy extended Hub carriers for the MK4 Golf platform cars which give the right results but has anyone seen anything "off the shelf" for a VR6 Corrado that will allow the extension of the lower balljoint.

 

Obviously it would be possible with welding etc.. but I would like something that bolts on to factory parts and is proven on either track or road.

 

I am happy about how to do the track rod ends (flip over) but the lower ball joint is a problem)

 

What have people seen?

 

Jay

[quicky1980 0]

I tried looking into this and ended in a dead end. Will keep an eye on this incase you do any better.

[24V Renshaw 0]

Yeah, I can't find anything useful. Its such a fundemental issue with the Corrado. The ride height is simply too high, which puts the C of G up and if you could lower the car, but retain the roll centre, then it would only be as good if not better than standard handling. Dropping the car to a visually appealing height just ruins the handling and you have to start sticking massive anti roll bars on to counteract it, which then ruins the ride and handling LOL.

 

I have designed my own extender, but I don't have the time or inclination at the moment to get it made, test it, develop it etc..

 

SCCH in the states do some nice stuff, but they are not straight forward fit.

 

Jay

 

---------- Post added at 12:54 PM ---------- Previous post was at 12:53 PM ----------

 

Surely VR6 Vento cup cars etc.. must have something or is it all fabricated?

[boost monkey 0]

Why not drop the car and drop the roll centre too? Is there any reason why you would like to keep the roll centre the same height?

 

I definitely don't know everything about suspension, but I just finished Motorsport Engineering degree at Oxford Brookes so would be happy to help if I can.

 

I'll have a hunt for some pics of VR hubs so I can see how your ball joints mount.

[24V Renshaw 0]

I am trying to keep the roll centre as good or better than standard. Of course if it can be better then great, but I think enough of a challenge it to get the same roll centre but with a lower CofG.

 

Products like this would be ideal if someone made a Corrado VR6 version

 

[/img]http://image.nengun.com/catalogue/original/nengun-0000-00-sunlineracing-roll_centre_adjuster.png

[boost monkey 0]

omg, deffo don't want to get a "nomal" one!

 

do you know what vertical distance the wishbones need to be adjusted to then sit flat, is it deffo 15mm?

 

I'm sure it would be possible for some CAD monkey to do a little design and then give a basic schematic to a machine shop.

[24V Renshaw 0]

You need to see a VR6 hub and and lower ball joint to see the challenge...

 

I have not done the maths yet of the actual length needed, but its a simple bit of trig based on the original position and ride height dropped....might do it over lunch :)

 

Jay

 

---------- Post added at 01:13 PM ---------- Previous post was at 01:10 PM ----------

 

Actually thinking about it, whatever the car is lowered by, the extension to the lower ball joint needs to be the same...

[boost monkey 0]

really? that sounds like some odd logic. If the vertical distance is reduced (std to -20, -40, -60 etc) then the angle the bone is at will be different each time.

 

Perhaps I should indeed try to look at a vr hub to see what is going on. Should be a simple affair to do though, finding a machine shop which will run of a low quantity amount may be harder.... potential GB?

 

---------- Post added at 01:31 PM ---------- Previous post was at 01:16 PM ----------

 

I think i can see some of the differences betwee the 4cyl and 6cyl LBJs. This is the VR item I think:

 

 

so instead if having a recessed groove all the way around which a bolt sits in to hold the LBJ in place, it torques up into the bottom of the hub and I guess that tapered shoulder provides an interference fit?

[24V Renshaw 0]

If you think about it, lowering the car by 40mm lowers the inboard pivot point of the wishbone by 40mm, so to get the wishbone back to stock position you need to extender/lower the outer pivot point (i.e the lower ball joint) by the same amount, 40mm.

 

You are bang on about how the VR ball joint works, now try and come up with a simple extension... :)

[boost monkey 0]

Ah yes, it's making sense. Cheers for that clarification!

 

I'd need some basic dims off both LBJ and hub, like:

 

inner diameter of hub hole,

outer diameter of LBJ shaft (M10/12 etc),

length of LBJ shaft,

required offset/extension,

other dimensions (i.e. does it need to clear anything through the suspension travel)

 

Grabbing an old VR hub and an LBJ would be a good start! but that still doesn't clarify whether it would interfere with suspension between bump and droop.

 

You could probably make a small part which had an interference fit from LBJ > extender, and also extender > hub, but it might be a total ballache to remove.

 

Using the pic above, perhaps something a little more complex with tabs that reach down to the most outboard LBJ mounting holes (not the slot) but this would increase manufacturing costs. I think a simple cylindrical design which can be lathed from a solid billet would be the best idea.

[quicky1980 0]

James, any chance I can see your design. I came up with one a while back but cant find it at the moment. If yours is better than mine (which wont take much) I may be able to have a very small batch made up for trial purposes.

[Kevin Bacon 5]

The only way to do this properly to withstand the huge forces involved, is with a modified (recast) hub carrier, which oddly enough is how VW do it. There is a company in America who do this but they hadn't got round to the Corrado when we last brought this up a couple of years ago.

 

I'll see if I can dig out the info....

[boost monkey 0]

Sounds useful CheeseFish.

 

I'm sure with some accurate modelling and stress analysis a component could be designed that would be able to cope withe the rigorous forces.

[quicky1980 0]

ball joint extenders arent anything new and seem to be used in the motorsport industry so it must be possible to come up with something for the vr6.

 

Admitadly Kev, having a new dropped hub would be the best method, are there non made for the vr6 golf as I thought they were the same part.