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xr_velocity

Massive Understeer At The Track, What To Do?

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Was after some advice. I hit Eastern Creek a few weeks ago, while I had a great time, my front tyres did not. Massive understeer all day, even before the tyres had got so hot they almost melted.

My setup is Lovells shocks and springs SSL all round with a 27mm sway bar on the front.

The rear end stuck like glue all day, even under full power out of corners there was zero slide from the back end. My tyres are fairly new Falken FK452 2435 19 and 275 30 19. I never expected them to be a good track tyre, but the understeer was very bad. The car had a Heasmans alignment a while ago, they set it up halfway between street and track.

Is there something else I should be doing other than buying slicks? I get the feeling that with the way the car was handling, slicks would just mask the understeer a little.

Edit: I am getting front lower and upper control arm bushes and control blade bushes done next week. All up $647 including alignment and fitting new power steering boot as mine is split. $400 labour from Bankstown Pedders, bushes are cost price from my brother. I thought I'd give Pedders a plug as I think that is a very cheap price.

Edited by xr_velocity

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You need negative camber on the front end to reduce the understeer, the way it is now the tyre is probably trying to fold under itself.

To add to that, a larger rear swaybar will help promote a more neutral stance since you already have the front bar fitted.

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How much do you guys do a proper alignment for?

I have heard mixed feelings about a bigger rear sway bar on these cars. What's the reason for going larger on the rear?

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Turn two would have been fun...not

The guys @ pedders should be able to do an alighnment to erradicate some of it.

I use 2.5 neg camber on the rear with 1mm toe. Works ok. But only about 10,000 k's at best from the tires.

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Full alignment including camber adjust is $95 :beerchug:

The larger rear bar increases the oversteer nature of the vehicle, since you have fitted a larger front bar (which increases the understeer nature) this will bring the car back to a more neutral setting.

If you don't like the idea of fitting a larger rear bar, just look into the extra camber, that should give you a decent increase in turn in.

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another in agree'ance with Senna_T, you need to stiffen the rear to loose a little grip to make the front gain it, it's all a balancing act.

Also depending on whether you have understeer going in or coming out of the corner can affect what adjustments are required

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I was at Eastern Creek early August too. Did you go on Monday or Wednesday?

I was in the silver FGXR6T with the black wheels.

I've gone through a set of Falken FK452's and they aren't really a track tyre. The temperature would really increase even close to 45-50psi after a few hard laps. What hot pressure were you running? Checking and adjusting the pressure is crucial to the car's handling. 35psi hot is a good starting point.

Rather than going to slicks (2nd hand Porsche cup front 18" Michelins are sometimes on ebay and cheap)I would try either Kumho KU36 or Federal 595RSR or Toyo R1R. Falken RT615 are good too. For more traction and street legal I'd try an R rated tyre like Toyo R888. Yokohama A050 or Dunlop DZ03G are even better but more expensive. Any of these above tyres will help you reduce your understeer compared to the 452's. Also is your front rim width 8" or 8.5"? That extra 0.5" does make a difference stopping the tyre roll slightly contributing to understeer and lets me honest, who couldn't do with an extra half inch!!?? ;-)

I also agree with the rear sway bar addition. I have the adjustable rear whiteline bar and had it in the middle setting at Wakefield experiencing huge understeer on the turns at the top of the hill. When I set it to the hardest of 3 settings, the understeer disappeared with all other variables constant.

Front camber kits are available for the BF's. A track wheel alignment with 3deg of negative camber would help reduce understeer significantly.

Driving Style also has a big influence on understeer. Maybe you are going into the turns too fast and coming out too slow?

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Thanks all. I am definitely not hitting the corners too fast, I was actually going in slow and still understeering. I didn't check the hot pressure, first time on a track day so that is something I have learnt! I will get myself a pressure gauge before the next one. Front wheels are only 8 inches, they were probably so overinfalted with the heat I had a small contact patch on the road.

I will give the rear bar a shot, will cost me bugger all cost price :)

$95 is a great price for a real alignment, if Pedders don't know what they are talking about (the alignment is included with the steering boot change), I will get it down to you for sure Senna. Heasmans charged me $180 last time!

I was at EC on a Friday, not Mon or Wed. It was a private practise day with the ARDC. Not bad I thought, $95 for the day with membership.

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I would IMO:

1. Lift the car back UP to std ride height. The current lower roll center (intersection of control arm pivots) and fixed c of g that the ssl setup is, actually means that the roll center has moved to a much lower point further away from the c of g. What this means is that the fixed c of g can now get much more leverage on the front of the car during cornering. That is where the forces in cornering are acting through. These cars usually hammer the outside edges of the front tyres. I presume that is where the tyre was most worn? Tyre wear pattern is always something I watch very closely. It's a great way to see what the tyre is actually experiencing and telling you about chassis setup. You can have more grip AND longer tyre life, the geometry and spring and bar settings just have to be correct to expose the full contact patch to the road. Lower is not necessarily better.

2. Pat is right in that a bigger rear bar will restore the balance. The bigger rear bar will lessen weight transfer to the rear, and hence grip to achieve that. More camber will then be requires to get then rear to not do the same to it's tyres as the front. My preference is to remove it though and try and get some weight transfer to the rear to help "unload" the front. The weight transfer in cornering is LATERAL and DIAGONAL. Chassis stiffness is the transmitter of that. With the 27mm front, that is in the zone, but I would remove the rear and see how it feels. That sharpens up turn in and mid corner grip as the load transfer makes the actual cornering load at each end of the car much more equal. This will actually help the front tyres to not roll over onto their outer edges so much. You can re-fit it if you don't like it. A no cost option. Have a close look at any rear wheel drive race car (that is well setup), particularly as it loads up it's suspension entering a corner. The rear will always have softer rear springs (traction) and more roll (cornering load balance). This is also why the V8 's fiddle with the rear roll centre. A turn "here or there" can make a noticeable difference. Raise it for less roll, lower it for more roll.

3. Do you know what rate the springs are on the front? I have gone from the std 520's to std XR height 620's.I am now thinking that King Springs have chosen this as a good compromise for sixes AND eights. They just seem that tad stiff for the lesser weight if the six. If I build the enthusiasm in the near future, I will get some made at about the 570-580 in/lb rate that I think will actually be an improvement from where it is now.

4. Those bushes mentioned are the ones to go for that will be the most value for dollar spent AND promote tyre (and diff/cv) life.

5. You need to get some more front camber into it. About zero is std. That is completely ineffectual for cornering. Dynamically when cornering (with the std bushes), the geometry probably goes into positive camber. Add body roll and you get the picture. The fronts have no chance but to understeer as they "fall over" onto their outer edges. Outer edges in distress usually take small chunks out of the leading edges of each tread block, or have a sort of ski ramp on each tread block caused by distortion under load. If you can get at least 1 degree negative that will help. More camber is better than more caster as to increase caster loses some camber (just the way the geometry is). More caster won't be as good as more camber, as it arrives "too late" to be effective for the small amount of wheel movement to negotiate a turn. It is also steering dependent, not load dependent as we want. About 1-1.25mm toe in per side should be the go for about 1-1.5 degrees neg camber. About 2.5 degrees is the max neg camber I would run on the street. I would also set it up with equal settings on each side.

Edited by Smoke them tyres

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How much neg camber can you get out of the stock parts?

You have mentioned more neg camber in the rear...is this adjustable stock or need a kit to do so?

Not sure on spring rates, will try find out today.

Edited by xr_velocity

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At this stage seing it was your first time at a track, I would just keep it simple and not touch the rear camber. Stock is fine. More negative front will be more beneficial for the track.

What you need in my opinion:

1. Better tyres (see my recommendations above), and set them to mid 30's hot.

2. A track wheel alignment at Wholesale Suspension with more negative camber.

3. A rear adjustable sway bar (set to max) seeing you already have the front sorted.

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Different tyres wont improve it. The Falkens are more than capable of a good flogging if the car is set up right. Too many people blame their tyres when its actually a poorly set up suspension. Some stiffer springs, sway bars and lower shocks doesn't automatically mean better handling. Unless they are all tuned and chosen for a specific feel, its all for looks and brag factor.

A rear sway bar will help alot, and so will negative camber in the front. It sounds like your spring rates in the front maybe too stiff though.

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If he has Lovells, I would be very surprised if the spring rates were too high, generally they are very soft in Falcons

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The spring rates are not too high, seat of the pants is a little firmer than stock.

Tyre wear on the rear looked very even, tyre wear on the front was all on the outer edge, chunks falling off!

I will try the sway bar with a more aggressive alignment then.

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Different tyres wont improve it. The Falkens are more than capable of a good flogging if the car is set up right. Too many people blame their tyres when its actually a poorly set up suspension. Some stiffer springs, sway bars and lower shocks doesn't automatically mean better handling. Unless they are all tuned and chosen for a specific feel, its all for looks and brag factor.

A rear sway bar will help alot, and so will negative camber in the front. It sounds like your spring rates in the front maybe too stiff though.

I disagree that better tyres will not improve the understeer. Sticky R rated tyres can often mask poor handling characteristics like understeer up to a certain level. However, I do agree that this is not addressing the cause of the problem. Just a bandaid cure, but one that will improve everything from braking to acceleration on a track day, so therefore first on my list of mod suggestions.

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Chunks off the front and understeer......I'm not surprised. On the front of the tread blocks no doubt? Pics?

A good read here would help our understanding of chassis dynamics.....http://home.scarlet.be/~be067749/58//index.htm

Different tyres will only change the overall characteristics (understeer) if the grippier ones are fitted to the front only.

The stiffer rear bar will restore the balance, but at a lower grip level than can be possible....re slower. This stiffer bar will cause less weight transfer to the rear outer in cornering. Therefore, it will induce more slide and more heating of the tyre over a run of laps.(That is why the Top Gear one lap dash is unrealistic. It should be done over 3-5 laps to accurately check how fast the car ACTUALLY is and then the average used).

Removing the rear bar (more weight transfer) will compress the rear suspension more, allowing shorter upper arm to do it's job of counteracting body roll. This will keep the tyre squarer to the road with no additional camber dialled in. The std rear spring is what I am running and I have no reason to change it.....std is spot on in this case IMO.

The max negative camber I could get out of my BF on each side on the front was 1 degree (minimal/nil shims), but trimmed equal on both sides. I now have 2.5 neg on each side on the front and response is much better again, although a few tricks have been employed to get this at the std ride height.

The Fulcrum upper arm mounts are exactly the same as std. All you need to buy is their slide in shims if the wheel aligner doesn't have them. The 1.5mm shim pack is the one to get if running minimal shims.

I would think that if the Lovells are only slightly stiffer as Pat has said, that they are right on the money. I wouldn't be changing those.

I think everyone should try it without the rear bar on....it's no cost anyway. I have done the same to a friends BA XR8 and he was surprised at how much better it was. I don't see the point in restoring the "balance" by detuning it and making it slower than it could otherwise be. It also adds no additional weight to these heavy cars once the heavier front is fitted.

Edited by Smoke them tyres

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The front understeer is not helped by a gripped up rear pushing it.

Using the stiffer bar on the rear end of the car will reduce the understeer and push of the car. But why do that to ungrip the rear when the real problem is still at the front? Traction over bumpy surfaces will be an unintended consequence of this stiffer bar. This does not help our cars, which are already somewhat under tyred.

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I have a 27mmm rear bar. And I took it off. And put the std one back on.

I am really not sure if it made it faster or slower on the track. It felt faster but it really got nervous at the limit. It did not drift it just went out very quickly at the rear.

It did stop the front pushing under throttle though. Turning in was always turn in grab some oppisit till the nose pointed where u wanted and then turn in again

I am running teins as well. It might be better with softer shocks though ?? or a fatter front bar. But its already 32mm or something like that on the FG

Edited by XR09

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I have a 27mmm rear bar. And I took it off. And put the std one back on.

I am really not sure if it made it faster or slower on the track. It felt faster but it really got nervous at the limit. It did not drift it just went out very quickly at the rear.

It did stop the front pushing under throttle though. Turning in was always turn in grab some oppisit till the nose pointed where u wanted and then turn in again

I am running teins as well. It might be better with softer shocks though ?? or a fatter front bar. But its already 32mm or something like that on the FG

There are a lot of factors when it comes to making these cars handle and there are really only a handful of people with real experience that have had success with trial and error over the years. Often the best theory does not work in practice. Wholesale suspension are good for street track applications, so are East Coast Suspenion in Sydney.

I went through this process last year and could not find any off the shelf products that suited my requirements. Ford engineers fitted the larger (from BF) 32mm front bar to the FG for a reason, but it is still hollow. I took it one step further and had a "solid" front 32mm front sway bar to my FG, fitted from Selby/East Coast Suspenion. I think Wholesale have a bigger one for FG now too.

Another, and I believe the most important factor to getting handling correct is matching your damping and spring rates. I went with a rebuildable Koni shock with custom made internals to suit the spring rate of my lowered springs. Costs a little bit more but worth it long term as a perfect street/track compromise.

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I am certainly going to do some more reading on this as I really only have a limited understanding.

So moving to the stiffer front sway bar has also brought more understeer at the same alignment settings, so why not go back to the stock bar with the stiffer springs and shocks that are on the car now? Is this also an option? I know the car feels a lot flatter now though through corners with the fatter front bar. Less body roll is supposed to be better yes?

I am far more inclined to remove the rear bar now and see how that affects the front. Though I will do that after an alignment at Pedders to gauge how each change feels. Do it all at once and I won't understand what has done what.

A stiffer rear bar is going to move more weight to the front when shifting weight in a corner? Hence taking weight off the rear? So in theory going to the stock front bar would have similar effect?

Edited by xr_velocity

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I am certainly going to do some more reading on this as I really only have a limited understanding.

So moving to the stiffer front sway bar has also brought more understeer at the same alignment settings, so why not go back to the stock bar with the stiffer springs and shocks that are on the car now? Is this also an option? I know the car feels a lot flatter now though through corners with the fatter front bar. Less body roll is supposed to be better yes?

I am far more inclined to remove the rear bar now and see how that affects the front. Though I will do that after an alignment at Pedders to gauge how each change feels. Do it all at once and I won't understand what has done what.

A stiffer rear bar is going to move more weight to the front when shifting weight in a corner? Hence taking weight off the rear? So in theory going to the stock front bar would have similar effect?

Every "expert" has a slightly different opinion. Set up is an art form and not easy!

Just keep it simple.

I prefer/recommend what has been proven to work in practice or works for your individual driving style.

For your next track day:

- Keep your stiffer springs/shocks and bigger front bar.

- Fit an adjustable rear Whiteline bar and play with the settings. As mentined previously, I found the hardest setting best to reduce understeer but it may be different for you as you have different springs/shocks and driving style.

- If your current settings provide a huge amount of grip at the rear, perhaps just change the front tyres to some Falken RT615's, next step up from the 452's if you are happy with this brand.

In the meantime, remove your rearbar and drive some twisty roads with your current set up. It's a no cost experiment. It may well be perfect for you personally and you won't need to purchase an adjustable rear bar.

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Set up is science isn't it????????

Less body roll is not necessarily better. What we are looking for is a "window" that the car will be happy with.

When I went the 680 front springs in mine, it had less cornering grip than the 620's for the same grip tyre. The tyre tended to slide at it's limit because there was not enough weight transfer ie high side load with limited downward weight applied. On the link I posted, there should be a graph that shows grip vs applied weight. It is not linear....that is why it is a "window" I suppose.

What we want is the softest suspension settings that will do the job. Fitting stiffer and stiffer components to the car can effectively "lock" the suspension in one position. Hardly dynamic or balanced at the limit.

A sway bar is too stiff when you get the car feeling like it has a side to side shimmy/rocking in it over different bumps on each side of the car. The bar should stiffen it up, but not to the point that each wheel cannot move independently of each other without rocking the chassis. It should complement the springs, not override them.

The 27mm bar with the Lovells springs and shocks at the front is in the zone. The rear springs that are std are also in the zone. I would keep those ON the car.

The std rear bar and the zero camber settings on the front have been put into the car to give it some understeer/push so that the average person does not get themselves into too much trouble. This is at the detriment of front tyre life. These are the 2 combined ways of managing the understeer in these cars. I don't believe it will be PROPERLY ELIMINATED due to the weight and limited tyre width of our cars, but they can be MUCH better.

I don't know why people are so obsessed about keeping the rear bar on. The utes don't have them from what I have seen. Just because it is fitted std, doesn't mean it has to stay there. This certainly works in the engine bay dept. What weight is there in the rear end anyway?.....basically sheet metal paneling as even the fuel tank is within the wheelbase now.I haven't had the rear bar on for a long time now and I am not convinced that I need to re-fit it anytime soon.

I think you are on the right path by getting the work done and doing a back-to-back comparison. Baseline testing is always the way to do chassis adjustments.

Edited by Smoke them tyres

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Interesting read. Spring rates need to have a relation to the tyres used...street tyres are meant to have a lot of slip angle, semis not so. You can get away, and exploit the potential of R tyres with heavier rates. I am not a fan of unsticking the rear with a bigger bar in order to fix "balance". I would also give the rear bar removal a run. I have seen it work on other RWDs before, and it would certainly help power down on exit on tight corners as it will help keep inside wheel planted.

My preference above all else would be to look for a 9' front at +30 or even a 9.5 +25 or so and run them "square" with matching rears (not staggered).

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I'm with Erko on not adding bigger bars to the rear simply to "unstick it"....the thing was "stuck" in the first place for good reason.

Camber has always worked for me...in the case of the BA I have gone beyong -3.0 to get it where I want it. Oddly I still get even tyre wear :bopp:

Other often forgotten things which have dropped my circuit times dramatically are decent wheels (read: lightweight) and trying to shift a little of the weight the BA/BF has sitting in all the wrong places.

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This is what Whiteline have to say about alignment on a BA I6:

Wheel alignment settings are of critical importance on any car and it seems Ford has all the settings pretty well

sorted. Front castor is left factory-standard (at a fairly generous 7.5 degrees) as is camber (at about -1.0 degrees),

but Whiteline elect to change from 0.5mm toe-in per side to neutral. This improves turn-in response. At the rear,

camber remains at -1.0 degrees while toe-in is reduced from 1.5mm per side to 0.5mm per side. Again, this enables

quicker direction change response.

Jim says the Ford has quite good front-end geometry that exhibits minimal bump-steer. "For 20mm of compression,

the front-end toes-in by an extra 0.5mm." At the rear, however, 30mm of compression gives another 1.5mm toe-in,

which is partly responsible for a counter-steer effect that Jim says is common to late-model Ford Falcons.

I was looking to try to get -2 to -2.5 camber in the front, standard caster and 0mm Toe in. The rear to have 1.0mm camber, 0.5mm toe in the quote above. All I have done is increase the camber on the front using whitelines settings, but I have no idea how more camber on the front affects toe in etc. So this is really an uneducated guess.

Would this be an acceptable set up with also removing the rear sway bar?

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