DIY adjustable camber ball joints mod

[sambb]

First dry night in a while so started getting the car ready for the weekends hillclimb. I fit my 20mm spacers to the front and its a no go. The wheels sit way proud of the guard lip now that the audi joints have increased the track - it just looks wrong really and would definitely get knocked back at scrutineering on the grounds that its not street legal. That left me only able to run my 12mm spacers. With them fit up, the front track is a touch wider than it had been pre-ball joint mod with the 20mm spacers fitted. But because of the camber it has now it doesn't look too out of place because the tyres are tipped in at the top.
I can confirm that the audi ball joints have changed the front geometry noticeably. When the front end was standard, the 12mm spacers felt weird I think because they were running at close to zero scrub eg strange squirming on down hill sweepers and really light pedestrian speed steering. The 20mm spacers had the steering feeling like standard again, nice and weighty, but obviously with positive scrub and a much wider track. Now, because the audi joints pivot much lower relative to the hub than the OE ball joints, the scrub radius will have moved more towards zero and so it takes less spacing out now to achieve the same result as before. This time the 12mm spacers felt wicked with nice meaty steering weight again and lots of feedback.
Theoretically now with a higher roll centre the car should be less inclined to roll, and by achieving the same wide track but with narrower spacers my wheel rate won't have dropped as much as when I had the 20mm spacers on, so overall the car will have more front roll stiffness than before (which you can definitely feel) so I should be able to get away with the front ARB on soft for the weekend I think and hopefully get some good drive coming out of the hairpins.

[Martin]

Theoretically now with a higher roll centre the car should be less inclined to roll

Probably not - the roll center was already in a good place
The reason the car leans/rolls is because it's up high and and is setup soft for comfort

It's when you lower the car that the roll center moves down away from the center of mass - which induces more lean/roll
Devices like the TT ball joints put the roll center back where it's meant to be - fixing the problem and making low work correctly

Never the less, one would assume all the work you've done should return better handling, good luck and keep us posted on how she performs in the hillclimb

[sambb]

I do see what you mean that at standard front ride height there is no roll centre height issue to correct yet.
With the original ball joints and at stock ride height the control arm pivots were basically dead level. This was measured at the front LCA pivot. The rear LCA pivot is much higher even with the anti dive reducing rear offset bush in place. To be honest in that situation I'm not sure if you are meant to take an average of the two inner pivots or use trig to work out a virtual inner pivot point that lines up in top view with where the ball joint sits. So basically the instantaneous centre with the OEM joint is governed almost entirely by the SAI.
But with the ball joint pivots now a full 10mm lower than the OEM's the roll centre would have to have risen because the SAI has increased by a degree and a bit and so has the control arm angle by more. But like you say it will have risen towards a COG that is unchanged because the ride height is unchanged so what effect it will have in that situation, I don't know.
For sure I agree that the real performance benefit of this won't be felt until I throw my lowered weitecs back in which should restore the factory geometry but with a lower COG. I don't have the stomach for any more work at the moment though - the garage floor is too cold atm. I would have thought the raised RC would have to be having some effect though but I guess there's every possibility that it feels less inclined to roll only due to the fact that the unspaced and spaced front track is wider than before.
At the moment its tricky because so many things have had to change due to the ball joints. eg I physically couldn't run the 20mm spacers because the track is so much wider and the 12mm spacers that didn't work well before now feel like the 20's used to in terms of steering feel. And where I needed to run the front bar on hard before to get a good balance, the car seems to prefer the bar on soft. On hard it is sharper and pointier than before with the new camber but is more inclined to spin up the inside front. I hate having to change more than one thing at a time. Even the rear will have changed from last time out because the 12mm spacers that I used there are now on the front, so the rear track will be back to stock and I'll have a wider front track by a smidgen. I don't think the bigger F:R track ratio will hurt me on the tight track i'll be on though and should even help. I'm hillclimbing at the same track as 3 weeks ago on sunday so if its dry I guess we'll see if changing about 4 things at once due to the ball joint change helps my time!!

[sambb]

hey martin I just measured my tracks and have a question. My front track with the BJ's and with the 10mm spacers on is 1450mm. My rear track std/no spacers is 1380. I could put my 20mm spacers on the rear to give F:R 1450:1420 and square things up. What do you reckon for a tight hairpin riddled track where you don't really get out of second.

[Martin]

My gut feeling would be to leave the rear in stock/narrow format
This may help the car being taily and eager to rotate
If you go wider the car may be less inclined to rotate and may increase understeer tendencies

Put the spacers in the boot and take them with you - an easy thing to try at the event if in need

[Notso Swift]

Agree, leave it but bring them along just in case you want to play. Problem with a HC the time is limited so I would only put them on if you don't like it with them off because it feels skitty (I don't think it will, it is not like you have a 155 on the back as well!)

[sambb]

yeah I think i'll do that. Its so cold up there in the mornings, usually about 6 degrees, that first run is always very slidey on cold tyres straight out of the boot. It won't be until second run that i'll get a proper idea. It looks like the track will be wet and then drying throughout the day which will make it even trickier, so that's why I was hoping for magic bullet advice, but yeah i'll just leave it be and only put them on if I'm all over the shop.
thx

[Martin]

Sounds like a plan

When it's cold and wet the last thing you want is understeer
The BTCC guys all set the car up to over steer in the wet

[sambb]

Got a correction to make. I'd been measuring tracks off the 'centre' tread line in my Re003's. It turns out to not even be in the centre so my tracks are a lot bigger. Going off the track widths in the manual (ET43 for my manual I assume), and then adding spacings and BJ mods to them, the tracks are:

stock: 1434:1426
audi BJ - no spacers: 1454:1426
audi BJ front 12mm:rear 20mm: 1478:1466

Today I decided to run the rear 20mm spacers which turned out to be a good decision. We drove from Sydney and it was dry until we hit thick fog and fog/drizzle at Newcastle. It was 8 degrees, foggy and damp and the pits were a bog. I managed to find a bay with road base stones that left the tyres cleaner but it was pretty atrocious conditions for the first time out in the wet on stone cold A050's.
First run was just 8/10 looking for dirt and any rivers on the track and it was slippery as hell. Second run was big time sideways at the first corner but kept my foot buried and drove out of it cleanly and similar on turn two. I was in first spot so far and then by run 3 there was a dry line appearing. Run 4 was my quickest. I did a 44.62 which was 0.22 quicker than last month and for the conditions on a grit covered cold track was a much better effort than last time. I was leading the class by over a second at this point. Going into my last run I watched as my mate in his clio lost it coming over the finish line and slid 20+m towards a concrete wall. He'd dipped his outside tyres onto the wet grass and looped it into a grass gully. If it wasn't for the marsh and the fact that his rims dug in just before the wall he wouldn't have stopped. Can't really say if that shook me but I did think I was clear enough to get the win. My last run felt quick but I clipped a witches hat on a corner they were policing to stop people getting wheels on the grass and got a 5 second penalty. That didn't loose it for me - I hadn't gone quicker anyway but somehow the guy that was in second went over a second faster on his last run and got top spot. So I finished second in class against a pretty mental VZ and saw off a another VZ, a new clubsport GTS, a 600hp XR6T an XR8 etc so pretty happy. If the time penalty from hitting that cone had cost me I'd have been spewing but I didn't go quicker on the last run and he beat me fair and square so I was stoked.
The 2 degrees didn't hurt power down. There was zero traction off the start line anyway and considering that it was colder damp then drying throughout and the track covered in grit and every start being made with dirty semi's, I'd have to say the new front end made a massive difference compared to last time out on a warmer bone dry track. Considering how planted the front end felt and that I really only had to worry about the rear, I think the mod has worked super well and I'm glad I didn't run the narrow track rear.
When the result sheet is sent out to us i'll stick it on the tracking thread

[sambb]

ouch I just saw the results - he beat me by 0.4sec! now I'm spewing.

edit: what the it was 0.04!!!

[Martin]

Great report

Scary moment for the Clio indeed

Good to hear the car is handling well

[sambb]

I just spoke to my clio mate. He said that after he gave the thumbs up to the marshals that he was ok, he found that he could actually touch the concrete wall and some blokes that were standing right there, beers in hand had their jaws on the floor.
I could trail brake deeper, get on the power earlier and just had so much confidence in it. I'll be happy to lower it now and will reposition the offset bushes for some more castor which should finish off the front end for a while.
thanks for all the advice peoples. its been much appreciated.

[sambb]

bit of an update. Because my control arm pivot points had moved for the better with the ball joint mod, I went ahead and re installed my weitec lowered springs. They are a tad stiffer than H&R's and their ride height is between stock and the H&R's (330mm from guard lip to centre). The control arm pivots and ball joint pivot point are dead level now.
At the same time I pressed out my rear LCA bushes that were in the anti dive position which lessens the anti dive geometry of the car and pressed them back in in the castor position. I just got the toe reset and it has jumped a full degree and a half from +4/1/2 degrees castor to 6 degrees. I left the camber on -2/1/4 degrees because in 7 weeks is the steepest, quickest and riskiest hillclimb on the calender at Huntley. After that i'll get the subframes and camber all finally set together at the end of the year.
So I've got some pretty good geometry numbers out of it now. Only thing left is to drive it and see if bump steer is going to be a problem. I'm hunting for some tie rod ends that may fix that if its an issue. Landrover discovery 3/4 may fit and offer steering correction as they have a really long ball pin but it may not be necessary.

Here's a vid of Huntley. Note the run off area? on the outside of this turn. To get a good time in road reg < or> 2.5L class, the aim is to get through there flat in third and then just brush the brakes through the esses. Its hard to see but its bumpy and narrow and steeper than going up the esses at panorama.

https://www.youtube.com/watch?v=uMMUAj3R00E