Best Track Set Up

[Stu 18]

Just my twopenneth, and not wanting to rock the boat, but here goes.. I run mine with a 309 GTI beam (my car is mainly a track car and was put together as such; but it does get used on the road) and find it much more 'planted' as a result..

 

As for the originally posed question, i run adjustable Koni's front and back, 309 GTI beam with a 21mm arb, 309 GTI bones and shafts and Baker mounts front and back. Not a fantastically expensive/intricate combination of bits but VERY effective; i do run slicks, but even on road tyres the balance is excellent; really well composed.

 

The black billies are a real 'budget' setup mate, i ran them prior to the Konis and the difference really is night and day.

 

Hope this helps!

[andyjstone 5]

You also have to factor in how good a driver you are!

 

Mine started off just over a year ago as a pretty standard 1.6 lowered by around 30mm with 15mm spacers on the back. I found it too soft and not knowing much about 205s and not having found this forum I 'upgraded' to Bilstein blacks, which did make an improvement, but not that much.

 

I have now changed everything, all the hubs et al are 1.9, rear beam is 309 (doesn't rub at all now, used to with the spacers) with solid mounts and Bilstein Challenge spec. dampers all round, front now has Eibach springs with Bilstein Challenge spec. dampers with BBM top rubbers and I have just picked up a 309 ARB from Baz, which I need to fit. I think this spec even without the uprated front ARB handles brilliantly, but it's currently at the stage where the car is way better than my driving so there isn't much point in playing further - yet

[Cameron 16]

Just my two pence here, but i think you're getting this back to front Cam.

 

As a result of increasing rear track, the weight transfer at the rear axle is essentially being decreased. The cars centre of gravity is lower towards the rear due to this wider spaced footprint thus increasing rear end grip and promoting more understeer.

 

That's how I understand the theory anyway

 

Nope.

 

The centre of gravity is unaffected by any of this, you're very slightly changing the roll centre height (the point at which the body rolls around due to the suspension geometry) by making the track wider, and that causes more weight to be transferred to the outside tyre, and more weight to be taken off the inside, reducing grip.

 

Yes, but there's a lot more to the physics than just weight transfer and it's almost impossible to work out what all the different combinations of track, springs, dampers, bars, etc., will have on the handling of the car going the physics route

 

You're absolutely right, but if only the track width is changed then it's easy.

 

Can I make a suggestion Cam? Speak from experience, not from what you think should happen "in theory" and certainly not implying that "theory" is fact

 

I've had a 309 beam on my car for years now, have built, fitted, and driven all manner of different beam specs, and I can confidently say that you're talking complete bo***cks frankly.

 

Nope, fair enough I don't have much in the way of "experience" to back up my claim. Believe what you want frankly, I don't mind. I don't want to turn a question about a good track set-up into a physics lesson, but you can appreciate that if I'm going to make these claims then I should at least back it up with something. Funny how most race teams that have the resources will use physics before anything else.. it can't all be bollocks!

Edited December 30, 2009 by Cameron

[evo rich 0]

im sorry about spelling i have got dyslexia i think im on the right track with wot i have got and wot i wont to get i just need to get some track days under my belt. i think a lot of people have got there opinion on this i just need to get out there and find wot i think feels right thanks for all the info and when is there a track day coming up let me no thanks rich

[Dazza 4]

im sorry about spelling i have got dyslexia i think im on the right track with wot i have got and wot i wont to get i just need to get some track days under my belt. i think a lot of people have got there opinion on this i just need to get out there and find wot i think feels right thanks for all the info and when is there a track day coming up let me no thanks rich

 

Iam sure all will understand the dyslexia issue ( my daughter also struggles with this and I certainly sympathise) .

 

Rich can i make a suggestion , I dont want to be an old boring Fahrt but what have you fitted inside the car to keep you safe , ie harnessses , cage , seats ...

 

Remember a 205 will wrap around you like a crisp packet should you decide to bin it off into somethig solid , and if you have got race seats and harnesses but no cage ..dont what ever you do roll the car as your in serious danger of the roof coming in on your head as you wont be able to duck down ..think about it Rich ..

 

Get a safe cell with you well strapped down within it before you do anything else ..Be safe ..and enjoy .

[Baz 421]

The centre of gravity is unaffected by any of this, you're very slightly changing the roll centre height (the point at which the body rolls around due to the suspension geometry) by making the track wider, and that causes more weight to be transferred to the outside tyre, and more weight to be taken off the inside, reducing grip.

 

That's a contradiction in terms though, as by increasing the track width you're reducing the chance of roll to the point of lifting the inside wheel anyway.

 

Feel free to educate me if you want to expalin the theory in your thinking etc though, i'm all up for learning, whether or not i agree it's directly applicable is another thing though.

[Batfink 201]

cameron is right on the theory. A wider track on the rear is supposed to give oversteer. But thats like for like and is not factoring the other differences that a 309 beam gives. A 205 with 15mm spacers at the rear is completely different to a 205 with a 309 rear beam.

[Atari Boy 11]

... when is there a track day coming up let me no ....

 

 

Here youy go, Cadwell Park, 25th March, Drivers/PSOOC track day

[Anthony 1,000]

cameron is right on the theory. A wider track on the rear is supposed to give oversteer

Theory used to say that bees couldn't fly...

 

My previous reply was probably somewhat blunt, but the reality isn't at all as Cameron was suggesting and misinformation like that isn't going to help anyone make a balanced and educated decision on a potential suspension setup. Never once have I had someone come back from driving a 205 GTi with a 309 beam for the first time complaining that the tail was sliding around like a greased weasel, nor have I had people from the D1 drift championship knocking on my door wanting to ditch their AE86's for one of these supposid super-sideways wide-axle 205's...

 

No, the responses are almost always the same - comments like "planted", "improved turn-in" and "no longer nervous on the limit".

 

Indeed, a 309 width beam on the back argueably has two downsides - one being that you're far more restricted on what width wheels you can run, and the other being that it argueably makes the rear end too planted and loses you some ability to steer the car on the throttle, particularly on lower-speed tighter sections.... which is actually completely the opposite to what Cameron was claiming!

 

I don't have a particular vested interest and I've rebuilt far more 205 beams than I have 309 ones, but I do object to nonsense being portrayed as factual information, especially when that person has never actually driven the combination that they're spouting forth about. Such misinformation will become "fact" left unchecked.... Mi16's having less torque than 8v's anyone?

 

Going back to the original poster for a minute, I'll echo what others have said - get the standard suspension setup working properly, drive the car in anger, and see how you feel and what area(s) of the setup you think need improving to suit your personal preferences and driving style. Standard 205 GTi's out of the box, whilst having much lower limits compared to modern hot-hatches, handle sublimely and do possess that certain something so lacking in many cars - they're not still one of the benchmark hot-hatches for no reason.

[evo rich 0]

Iam sure all will understand the dyslexia issue ( my daughter also struggles with this and I certainly sympathise) .

 

Rich can i make a suggestion , I dont want to be an old boring Fahrt but what have you fitted inside the car to keep you safe , ie harnessses , cage , seats ...

 

Remember a 205 will wrap around you like a crisp packet should you decide to bin it off into somethig solid , and if you have got race seats and harnesses but no cage ..dont what ever you do roll the car as your in serious danger of the roof coming in on your head as you wont be able to duck down ..think about it Rich ..

 

Get a safe cell with you well strapped down within it before you do anything else ..Be safe ..and enjoy .

 

thanks for understand about the dyslexia issue. i have got a set of buckets and harnesses and a half cage but it used to be a full cage but for some strang reson they have made it into a half cage. so im going to make it back into a full cage agen. thanks rich

Edited December 31, 2009 by evo rich

[Cameron 16]

That's a contradiction in terms though, as by increasing the track width you're reducing the chance of roll to the point of lifting the inside wheel anyway.

 

Feel free to educate me if you want to expalin the theory in your thinking etc though, i'm all up for learning, whether or not i agree it's directly applicable is another thing though.

 

Ok, so I'll explain.. The vehicle centre of gravity is in a fixed position dependant on the location of mass throughout the vehicle. Only by redistributing mass can you change the location of the vehicle CG. The roll centre is the point at which the body of the vehicle will rotate around, and is a function of suspension geometry and track width. So imagine you have a vehicle with CG 0.5m off the ground, and a roll centre at 0.2m off the ground; the CG is then 0.3m higher than the roll centre. When you go round a corner the force of the GC being pushed outwards (centrifugal force) causes a moment (torque) around the roll centre, much like applying a load to the end of a wrench. This then causes load to be transferred from the inside wheels to the outside.

 

So, by widening the track you are lowering the roll centre, but the CG height stays the same as the vehicle mass is unchanged. This means you are effectively extending the distance between CG and RC, which means a greater roll moment is applied - think applying the same force to a longer wrench.

This means that more weight is transferred from the inside wheels to the outside.

 

Now how all that fits in to the amount of grip you get is down to tyre behaviour, in that the grip available from a tyre is proportional to the amount of weight on it. But, the relationship between weight and grip is non-linear, which means you get less increase in grip as more load is added. So when you have lots of weight transfer to the outside tyre, you are gaining grip on it - great! But the inside tyre is losing grip. And since the relationship of grip to weight is non-linear you have lost more grip on the inside than you have gained on the outside, thus decreasing the mean grip for that axle.

 

This is why only increasing the rear track will cause the car to lose grip at the back. You all seem to have mis-quoted me so far, especially Anthony. At no point have I said that fitting the 309 beam will cause you to lose rear end grip. What I've said is that it won't offer the same improvement as fitting the same "package" (i.e. springs etc) to a standard width beam. This isn't misinformation, it's the bloody truth I'm afraid! You carry on fitting 309 beams, as I said the benefits of the stiffer springs will outweigh the shortfall in grip. My point was only that you don't need the extra track width.

Edited December 31, 2009 by Cameron

[welshpug 1,627]

Anyone know how a 106's handling compare to a 205? I've driven a few 106's and liked the way they drive, but none had rear ARB's so are hard to compare

 

If they can match a 205's feel they they concrete Cameron's argument that the extra width is not needed, just decent torsion bars, or maybe people should just buy a 309 and be done with it!

[Atari Boy 11]

maybe people should just buy a 309 and be done with it!

 

[andyjstone 5]

Maybe I should swap my 309 rear beam for a 106 rear end

[Rob Thomson 6]

So, by widening the track you are lowering the roll centre, but the CG height stays the same as the vehicle mass is unchanged. This means you are effectively extending the distance between CG and RC, which means a greater roll moment is applied - think applying the same force to a longer wrench.

This means that more weight is transferred from the inside wheels to the outside.

 

How does changing the track affect the roll centre? The geometry of a 205/309 beam is fairly simple; surely the roll centre will either be at ground level or at hub level (can't get my head around that today) but I don't see how track would affect it either way... Please explain.

Edited December 31, 2009 by Rob Thomson

[Rob Thomson 6]

Anyone know how a 106's handling compare to a 205? I've driven a few 106's and liked the way they drive, but none had rear ARB's so are hard to compare

 

If they can match a 205's feel they they concrete Cameron's argument that the extra width is not needed, just decent torsion bars, or maybe people should just buy a 309 and be done with it!

I used to rally a 106 Rallye with a 106 GTi beam. Hated it, but that's probably because the front end wasn't standard and I'm sure the geometry was totally f***ed, i.e. the caster was verging on being negative (whatever it is when the strut leans forward?). Most people say that the 106 handles pretty well though, and they've all got a very narrow rear track in relation to its front.

 

It's interesting to note that the 205 1.6 GTi has a wider front track and narrower rear track than the 1.9 GTi. A lot of people say the 1.6 handles better than the 1.9. Mine is wonderful, much better than the 1.9s I've driven though I will concede they haven't been all that numerous and were probably f***ed.

 

Then, handling isn't the same as roadholding, and on track you might want to compromise one against the other.

[Batfink 201]

Theory used to say that bees couldn't fly...

 

My previous reply was probably somewhat blunt, but the reality isn't at all as Cameron was suggesting and misinformation like that isn't going to help anyone make a balanced and educated decision on a potential suspension setup. Never once have I had someone come back from driving a 205 GTi with a 309 beam for the first time complaining that the tail was sliding around like a greased weasel, nor have I had people from the D1 drift championship knocking on my door wanting to ditch their AE86's for one of these supposid super-sideways wide-axle 205's...

 

No, the responses are almost always the same - comments like "planted", "improved turn-in" and "no longer nervous on the limit".

 

Indeed, a 309 width beam on the back argueably has two downsides - one being that you're far more restricted on what width wheels you can run, and the other being that it argueably makes the rear end too planted and loses you some ability to steer the car on the throttle, particularly on lower-speed tighter sections.... which is actually completely the opposite to what Cameron was claiming!

 

I don't have a particular vested interest and I've rebuilt far more 205 beams than I have 309 ones, but I do object to nonsense being portrayed as factual information, especially when that person has never actually driven the combination that they're spouting forth about. Such misinformation will become "fact" left unchecked.... Mi16's having less torque than 8v's anyone?

 

Going back to the original poster for a minute, I'll echo what others have said - get the standard suspension setup working properly, drive the car in anger, and see how you feel and what area(s) of the setup you think need improving to suit your personal preferences and driving style. Standard 205 GTi's out of the box, whilst having much lower limits compared to modern hot-hatches, handle sublimely and do possess that certain something so lacking in many cars - they're not still one of the benchmark hot-hatches for no reason.

 

there are other factors that need to be taken into consideration which back up the real world experiences. A wider track will reduce role and the tyre will therefore have a more optimum contact patch with the road surface, giving better traction. I'd say thats a bigger factor than the roll centre stuff..

With Robs coments about the 1.6 rear being thinner..many years ago I found that under heavy braking and standard suspension my old 1.6 would snake a little at the rear. I've never had that on a 1.9 or 309 beam since so it could have been my s*it driving I'll still state that the biggest difference in handling is down to the lighter 1.6 alloys though..

 

Thinking about the beam widths again. Cameron pointed out about grip not being linear. Now is the 309 beam a more optimum setup with a more even balance between the wheels. I think we can safely assume that the 205 as standard is not going to be at an ideal or optimum width. Surely we have to look at ratios between the front and the rear to work out on paper how good a change will be.

Edited December 31, 2009 by Batfink

[Cameron 16]

Right, this is going to be difficult to follow without a diagram, but here goes..

 

To calculate the roll centre, first you have to find the point at which the wheel is rotating through suspension travel - as the wheel moves up / down in an arc when viewed from the front. You do this by extending the lines of the wishbones (in a double wishbone setup) until they cross at a point in space, this is called the instantaneous centre of rotation. For McPherson struts, you draw a line perpendicular to the top of the strut until it meets the line of the bottom wishbone, and for trailing arms the IC is at an infinite distance to the side of the wheel, since they don't actually move in an arc.

 

And annoyingly I've hit a wall.. since the IC for trailing arms is an infinite distance to the side it turns out the roll centre for trailing arms has to be at ground level, so doesn't actually change height when you change the vehicle track! The problem becomes much more complicated!

 

But I'll finish explaining anyway.. for suspension systems OTHER than trailing arms, you then draw a line from the centre of the contact patch to each IC (since there are 2, one each side) and the point at which they cross is the roll centre. It then follows that if you make the track wider you are lowering the roll centre.

 

So I'm going to rack my brains and see if widening the track with trailing arm suspension does actually affect the weight transfer, I assume it still does.

[Cameron 16]

Ok, luckily I have a very good piece of lateral load transfer software.

 

Here is the 205 width rear cornering at 0.8g

 

 

And here is the 309 width rear cornering at 0.8g

 

 

As you can see, more weight is transferred to the outside rear wheel, decreasing rear end grip.

Less weight is transferred at the front, increasing front end grip, which explains the better turn-in etc that people comment on.

[Dazza 4]

Hi Welshy , in my experience ive driven all the models 309-205-106 on track and all were really good to expliot and push to the point at which they are ragged and going to the hedge-line with lost abondonment..

 

The 309 was reasonably stable with good turn in that caused the rear to lighten up and allow me to change the line into the apex to exit on power , nice and easy to push with plenty in the wings for correction .I would say these are great cars to drive , easier in terms of feedback that the others on the limit.

 

The 205 i use is imo brilliant at what the 309 experiences were albeit much sharper and you need to be ready for any level of grip /asphalt change to cause it to either grip and realign or snap out and you need to snap the throttle and twich it back in .

 

The 106 GTI is a laugh a minute , the one i drove was on uprated mac's and springs , stripped and caged and about 140 horses .This little "tub-of terror" was hilarious around Croft and Oulton Park it just rev's and rev's and was so flexible and forgiving , the turn in was shaper than the 205 and the rear end just dug in for fun .I would say given the same power as my 205 it would be an easier package to drive (POWER STEERING) . I like these very much , my mate just cant keep with mine due to power .

 

However i was in another mates 106 GTI S/C at Oulton 18/12/09 and thats a reputed 240 Horse screemer , that was one quick little motor around there and its got the Evo's under its belt ....

Edited December 31, 2009 by Dazza

[pug_ham 242 3 Cars]

Here is the 205 width rear cornering at 0.8g

 

 

And here is the 309 width rear cornering at 0.8g

 

 

As you can see, more weight is transferred to the outside rear wheel, decreasing rear end grip.

Less weight is transferred at the front, increasing front end grip, which explains the better turn-in etc that people comment on.

But does the fact that you have more load on the r/h rear wheel mean you also have a better contact patch & effectively more grip on that wheel? 38.1% vs 38.4%.

 

On both cars the inside rear wheel is off the ground so doing nothing but the front l/h figure is higher indicating more grip where the r/h figure is lower with the 309 beam so would the car understeer sooner.

 

Graham.

[Baz 421]

cameron is right on the theory. A wider track on the rear is supposed to give oversteer. But thats like for like and is not factoring the other differences that a 309 beam gives. A 205 with 15mm spacers at the rear is completely different to a 205 with a 309 rear beam.

 

Oh i'm well aware of the theory and how right it would 'appear' to be, but as i keep saying, it just doesn't work like that in practical terms. By that i'm not saying the theory isn't correct!

[Rob Thomson 6]

But does the fact that you have more load on the r/h rear wheel mean you also have a better contact patch & effectively more grip on that wheel? 38.1% vs 38.4%.

 

On both cars the inside rear wheel is off the ground so doing nothing but the front l/h figure is higher indicating more grip where the r/h figure is lower with the 309 beam so would the car understeer sooner.

 

Graham.

 

Yep, so what the wider rear track does in this example is reduce weight transfer to the front. That means more grip at the back.

Edited December 31, 2009 by Rob Thomson

[Baz 421]

I'll still state that the biggest difference in handling is down to the lighter 1.6 alloys though..

 

Toffee. A set of wheels doesn't make that much of a difference. IMO a 1.6 with either wheels still handles the same.

 

And on the snaky back end under braking, i'd hazard a guess something else was awry.

 

Certainly i've experience many a snaky rear-end under heavy braking on 1.9's, down to the common faulty compensators, but this is no where near as common on a 1.6.

[Batfink 201]

so with more grip at the front and more at the rear, everyones a winner!