Tracking for trackdays & bumpsteer!

Anybody on here experimented with different tracking settings for circuit use?? Toe-in/out or neutral.

Thoughts please, don't just want to hear set it to this, that or the other but rather what experiences peeps have had/felt using different setting?

Secondly anybody got there own gauges/string and set it themselves??

cheers
Ian.

 

do all my own geometry with string, bits of wood and old tech drawing kit, only 'fancy' thing I have is digital spirit level from usa - cost 70 USD.

toe - toe out makes car sharp and twitchy, turns in well but upsets braking and high speed stability, toe in really improves braking feel

sometimes I run different camber side to side but set combined toe with equivalent camber side to side, (say 5mm toe out total across both wheels) then adjust camber on one side and have calibrated how much of a turn of the tie rod brings this back t what I want

have seen the guys in the british gt paddock with bits of string and whatnot so figured if its good enough for them its good enough for me

 

Aren't all Nascar's setup wiith string? One of the set up tool suppliers are Autosport was telling me they could sell anything to the yanks as long as it had string attached.

 

Yep, what RobT said. But Toe out does tend to eat tyres much much quicker. Mk1 has a slight toe out set from factory along with its slight +ve (yes i said +ve) camber.

Gurds

 

-ve, I'm pretty sure...

 

According to the haynes book of lies it's positive too.

Anyway the point of this post was that after recently changing my tie rod ends for rose joints so i could attach the steering arms below rather than on top of the hub (to reduce bump steer), i've had some geo issues.

i got the tracking reset to 0 toe after fitting the rose joints and the bumpsteer was non-existant but the car seemed to wander over undulations and road cambers a lot more, i thought i'd wait till the next trackday before making final judgement. I was at Zandvoort last week and the car was actually dangerous on a fast left right left section over a couple of brows, the car would literally go from one side of the track to the other without the steering wheel moving at all. The general steering effort and amout of necessary lock was greatly reduced, also the car seem to have a very oversteery balance, seeming to pivot around the middle in long bends (which was quite nice!).
I swapped the arms back above the hubs at lunchtime (which i could see increased toe-in quite a bit) and the results were very different, dead stable and flat out through the high speed undulating section, but the bump steer was back, as was increased steering effort and lock and the car was a lot more understeery.

Now my 1st thought, which i'm hoping is correct (not checked yet) is that the garage who did the tracking, cocked it up and the car was toeing out a lot, which was counteracted by moving the arms back above which in turn made it toe-in a bit too far.

Or could the new position of the steering arms be the cause?? Fixed under the hub on level ground they are dead straight, above the arm (in factory position) they point up to the hub carriers from the rack.

i'd love the arms to stay below the hubs as the steering was much nicer, without the usual vicious kick back thro the wheel but it really was unsafe at high speeds over cambers in the road.

Who else runs their steering arms in that position?? motorhead, nick, mr hillclimber, reeves, chris ?????

 

Lizard was telling me about it last night, sounded 'interesting' to drive !

I don't know much about it all tbh, hopefully someone does.

Sounds about right, they may have seen the rose joints and started sweating that it wasn't the norm?

 

It was actually a lithuanian bloke with a massive bandage on his head i nearly said sod it i'll take it somewhere else, but other than his lack of english he seemed alright, apprently back home he was a rally mechanic and his mate will be driving in this years RAC. He even managed to drive it in without stalling it, every other tyre monkey always does, even after i warn them it's got a snatchy clutch!

 

Hey, I stalled it [:^(]

 

just bumped this part, input greatfully received

 

If the steering arms are moved down, the ball joint has to go down too - can't just move one (although I was assuming to start with that both were moved..).

The wishbone and steering arms move through fractionally different arcs due to different pivot points, the steering arms pivoting further inboard than the wishbone pivot. Therefore the OE settings are a compromise, designed to minimise bump steer and geometry changes in the majority of the operating range, at OE ride height.

I assume as a base line that the OE setting of the wishbone and steering arms minimises bump unwanted geometry changes. Dropping the ride height will move the car out of the median of this operating range, with little discernable effect (since lowering kits would be unsaleable otherwise).

But I suspect correcting it visually by re-paralleling the steering arms with the wishbones for the lowered ride height operating range is to do the obvious, but miss the wider geometry implications. Theory says it will move those OE steering arm-to-wishbone relative settings markedly and put the geometry well outside that median range.

(Haynes camber settings have got me well puzzled btw - will get head into book!)

 

Cheers Chris,
that makes sense, no i have not lowered the bottom ball joints yet as i still can't see an easy option for doing this.
I was just trying to compensate the existing bumpsteer caused by lowering the car by levelling the steering arms, had not thought that the ball joint pivot point would affect this. I know Motorhead had done it with good results on his mk2.

But thinking about it, by lowering the bottom ball joint therefore raising the hub, would this not bring the arms back to their original unlevel postion and return the bumpsteer???

 

I had an MSN recently with Daz and my initial view was this wasn't technically correct. The car apparently had a handling characteristic which pointed towards that mod being responsible - though may be best if Daz elaborates.

The hub stays where it is, dictated the wheel joined on the hub, the spring above it, and the car on top of that. Both the w/bone and steering arm need to physically move down..

 

Ahh penny drops, yes of course.

so back to how to lower the wishbone.
balljoint spacers?? What material would that need to be made of to be strong enough, i know Nick mentioned a few of his beemers had gone into the wall where the cone had failed (going back to the thread from the other day).

 

i remember reading something about moving the ball joint below the arm on a article on a mk1 golf in revs years ago, always wondered how htis was possible as i run a low mk2, will be following this thread with interest guys. good luck!!!!

 

'EN 40B'-type sexy steel basically, presumably heat treated, or a high angle rose joint in place of the ball joint, plus the spacer (c/w radiused machining for strength).

 

http://forums.vwvortex.com/zerothread?id=2485086

I haven's touched mine yet but aill do the whole lot on one go, i'm going to space the ball joints, run the tie rods underneath the arm on the hub and fabricate some rose jointed wishbones so i can adjust the castor aswell.

 

Lots of tasty products from these people.

http://www.pmwltd.com/gallery2.html

Gurds

 

ooooo nice!

 

Good finds fellas, funnily enough i was having a poke around on vortex yesterday pm aswell, i'll add a couple of links later to the useful pages i found.