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Everything posted by xr_velocity
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Massive Understeer At The Track, What To Do?
xr_velocity replied to xr_velocity's topic in Wheels and Tyres
You are good with the explanation mark key though -
Massive Understeer At The Track, What To Do?
xr_velocity replied to xr_velocity's topic in Wheels and Tyres
Any pictures Rosie? -
Massive Understeer At The Track, What To Do?
xr_velocity replied to xr_velocity's topic in Wheels and Tyres
Where do you mount your engine oil cooler? There is little space in the front with the water bottle on the left and in bumper air intake on the right....I am thinking maybe behind the head light where the original air box was. There is some airflow through there around the headlight...also keeps it out of harms way in case of a front ender. -
Massive Understeer At The Track, What To Do?
xr_velocity replied to xr_velocity's topic in Wheels and Tyres
Thanks for the tips. Will get the wrap just for now and look at ceramic later. It does amaze me how the dump pipe stays together at all given the extreme changes in temperatures it goes through especially at the track. The other thing that melted was the battery cable running along the chassis rail, put some silver heat reflector around that one. Need to inspect it soon. Engine mount will probably cop a flogging like you said. I suppose it's all a part of maintaining a 900 degree part of the engine bay I could always put Homer speed holes in the bonnet! -
Massive Understeer At The Track, What To Do?
xr_velocity replied to xr_velocity's topic in Wheels and Tyres
King 520lb springs installed. General driving they feel the same as they are progressive rate. Can't wait to hit the track with them. The added ride height is brilliant, no more hitting the bumper on the road! Whilst I was under it, I noticed some heat affected areas from the turbo and dump pipe, notably the steering boot under the turbo just melts under the heat. Need to have a new one installed and some heat shielding added. Will be wrapping the dump pipe in heat wrap in a couple of weekends time as well to try keep all that heat from destroying my engine bay! -
Massive Understeer At The Track, What To Do?
xr_velocity replied to xr_velocity's topic in Wheels and Tyres
My thoughts on Eastern Creek track.....brilliant track! Plenty of fast sweeping corners and tight technical turns as well. It is a great track to learn at as you face just about every scenario possible in one lap. It takes some time to learn it though. At the moment I am loving turn 4, a sweeping right handerat the bottom of a down hill, I can get about 1.2G through that one, it has a tricky exit where you have to power out and get yourself set up on the opposite side of the track under brakes. A lot of people have come unstuck on that corner and hit the concrete! They really need some kitty litter there. The other is turn 11. Coming down from about 140 into turn 10 a slight right hander, having to brake and set yourself up on the far right to throw the car into turn 11, a nice flowing left hander that you can take deceptively quicker than what it looks like you could. Plenty of grip there. One area of the track I don't have the knackers yet to master is turn 1! I can see the fast guys are on the gas all the way down the straight and brake into the corner, whereas I brake well before the corner from about 210- 215 and roll into it at about 150. With a bit more practise I will be able to do as they do, but for now my dacks have stayed clean and the car in one piece! Once I have more confidence in the car and how it reacts, it will change my confidence levels. In this initial setup phase I am still very cautious. -
Massive Understeer At The Track, What To Do?
xr_velocity replied to xr_velocity's topic in Wheels and Tyres
What alignment settings is everyone running? Front and rear toe, camber and castor? -
Massive Understeer At The Track, What To Do?
xr_velocity replied to xr_velocity's topic in Wheels and Tyres
I already have the springs, I get it all at cost price thanks to a brother that works at Burson and a mate whose family owns a car parts store. If they are a step backwards I can always ebay them and get some new ones, will only cost me a couple of alignments anyway. My old Lovells will be going on ebay, someone will like the very low look. The rear end is definitely improved, it was a lot easier to steer with the throttle without the rear bar. The feel from the rear end is very good, it's progressive, no sudden movements, just linear slides on the throttle. It is still far superior to the front end grip. Though the front is still too soft, under brakes it unloads the rear tyres too much taking away some grip. The rear end was moving around a little braking from say a right hander into a left hander. That sort of movement unsettled the car a little. There is still much more to be gained in the front. The outside edges of the front tyres no longer exist! They were scrubbed away once the tyres got too hot, combine that with not enough front camber and say goodbye to those tyres. The next track day is in November, so I have some time to get the front springs in, a camber kit and an engine oil cooler....the engine oil overheats in the afternoon on a 21 degree day, mornings are OK, I can go the whole 20 minute session. Other than the engine oil temp, the rest of the car has fared well in terms of heat. I will also be wrapping the turbo dump pipe in some of that heat tape to try and keep the engine bay temp0s down a bit and to prevent and items surrounding the dump pipe from melting. Just a note to others out there about engine bay heat, there is a red battery wire that runs along the chassis rail below the turbo, this will melt through the plastic exposing the live wire.....wrap this in some heat reflective stuff. The Ferodo DS2500 front pads are brilliant compared to the stock Brembo pads! The Brembos were good and reliable at the track but do not have the stopping power of the Ferodos, they did last 3 track days, a couple of Powercruises and about 20000km so not complaining. The Ferodos took two sessions to bed in. While bedding in I had to take it easy, initial bite was great, but once they got heat in them they lost any ability to create friction. But once the third session came about, they were awesome. Where I would normally brake hard with the Brembos, I would have to back off the pedal with the Ferodos because they kept making the ABS go off. I have to get some stickier tyres to take full advantage of them. Coming into a 150kmh + corner the ABS would go off meaning I would have to back off the brake and get back on it again. Turn 2 is hard on brakes, hit it at bout 165kmh and have to get down to about 60 or 70 for the hair pin. I overshot that corner thanks to the ABS a couple of times. I also have the PBR 328mm rear brakes on now with Bendix Ultimates. They do the job, at least they did not crumble apart like the old QFM A1R pads on the original solid disks. -
Massive Understeer At The Track, What To Do?
xr_velocity replied to xr_velocity's topic in Wheels and Tyres
I will drop the pressure again next time. Thanks. -
Massive Understeer At The Track, What To Do?
xr_velocity replied to xr_velocity's topic in Wheels and Tyres
Took the Tyre pressure down to 36lb and found a whole lot more front end grip on the third session. Was running 41 hot prior. Best lap time of 2:00 again but didn't ge enough clean laps without traffic. Maybe this arvo I'll get under 2 -
Massive Understeer At The Track, What To Do?
xr_velocity replied to xr_velocity's topic in Wheels and Tyres
Two sessions without the rear sway bar on now, FMD what a massive improvement in front end grip. Chalk and cheese the rear bar will never be put back on! I can hit the apexes now! No loss of rear end stability or grip either, wouldn't say it's better, but wouldn't say it's worse either. The added front end grip really highlights that the street tyres are not up to it. Haven't run a decent time yet as still bedding in pads. A few sessions to go though. I am only 5 seconds off my best time with taking it very easy. I didn't get around to putting the king springs 520's in either. Still Lovells 410's. Happy days, now I need tyres. -
Massive Understeer At The Track, What To Do?
xr_velocity replied to xr_velocity's topic in Wheels and Tyres
Once the 520lb king springs go in and stiffen the front, I am thinking if I still get a bit too much understeer to go back to the stock front roll bar to see how it goes. Going by all the info I posted above of handling symptoms, my own personal situation is that I can initially turn in great, but once the front outer becomes loaded it just slides and scrubs the outside shoulder of the tyre. THe car is just rolling over onto the outer of the tyre. Firmer front springs may help it to hold camber better if more level. -
Massive Understeer At The Track, What To Do?
xr_velocity replied to xr_velocity's topic in Wheels and Tyres
Some info I read on another forum, seems very informative and helpful: http://www.aussiestreetcars.com/showthread.php?t=1118 CARROLL SMITH’S CAUSE AND EFFECT GUIDE RIDE AND ROLL RESISTANCE-SPRING Too much spring: overall • Harsh and choppy ride • Much unprovoked sliding • Car will not put power down on corner exit – excessive wheel-spin Relatively too much spring: front • Understeer – although the car may initially point in well • Front breaks loose over bumps in corners • Front tyres lock while braking over bumps Relatively too much spring: rear • Oversteer immediately on application of power • Excessive wheel-spin Too little spring: overall • Car contacts the track a lot • Floating ride with excess vertical chassis movement, pitch and roll • Sloppy and inconsistent response • Car slow to take a set – may take more than one Relatively too little spring: rear • Excessive squat on acceleration accompanied by excessive rear negative camber, leading to oversteer and poor power down characteristics • Tendency to fall over on outside rear tyre and ‘flop’ into oversteer and wheel-spin ANTI-ROLL BARS Too much anti-roll bar: overall • Car will be very sudden in response and will have little feel • Car will tend to slide or skate rather than taking a set – especially in slow and medium speed corners • Car may dart over one wheel or diagonal bumps Relatively too much anti-roll bar: front • Corner entry understeer which usually becomes progressively worse as the driver tries to tighten the corner radius. Relatively too much anti-roll bar: rear • If the imbalance is extreme can cause corner entry oversteer • Corner exit oversteer. Car won’t put down power but goes directly to oversteer due to inside wheel-spin • Excessive sliding on corner exit • Car has a violent reaction to major bumps and may be upset by ‘FIA’ kerbs Too little anti-roll bar: overall • Car is lazy in response, generally sloppy • Car is reluctant to change direction in chicane and esses Relatively too little anti-roll bar: front • Car ‘falls over’ onto outside tyre on corner entry and then washes out into understeer • Car is lazy in direction changes Relatively too little anti-roll: rear • My own opinion is that on most road courses a rear anti-roll bar is a bad thing. Anti-roll bars transfer lateral load from the unladen tyre to the laden tyre – exactly what we don’t want at the rear. I would much rather use enough spring to support the rear of the car. The exception comes when there are ‘washboard ripples’ at corner exits, as on street circuits and poorly paved road circuits. SHOCK ABSORBER FORCES Too much shock: overall • A very sudden car with harsh ride qualities, much sliding and wheel patter • Car will not absorb road surface irregularities but crashes over them Too much rebound force • Wheels do not return quickly to road surface after displacement. Inside wheel in a corner may be pulled off the road by the damper while still loaded • Car may ‘jack down’ over bumps or in long corners causing a loss of tyre compliance. Car does not power down well at exit of corners when road surface is not extremely smooth Too much bump force: general • Harsh reaction to road surface irregularities. • Car slides rather than sticking • Car doesn’t put power down well - driving wheels hop. Too much low piston speed bump force • Car’s reaction to steering input too sudden • Car’s reaction to lateral and longitudinal load transfer too harsh Too much high piston speed bump force • Car’s reaction to minor road surface irregularities too harsh – tyres hop over ‘chatter bumps’ and ripples in braking areas and corner exits. Too little shock: overall • Car floats a lot (the Cadillac ride syndrome) and oscillates after bumps • Car dives and squats a lot • Car rolls quickly in response to lateral acceleration and may tend to ‘fall over’ onto the outside front tyre during corner entry and outside rear tyre on corner exit. • Car is generally sloppy and unresponsive Too little rebound force: overall • Car floats – oscillates after bumps (the Cadillac ride syndrome) Too little bump force: overall • Initial turn in reaction soft and sloppy • Excessive and quick roll, dive and squat Too little low piston speed bump force • Car is generally imprecise and sloppy in response to lateral (and, to a lesser extent longitudinal) accelerations and to driver steering inputs Too little high piston speed bump force • Suspension may bottom over the largest bumps on the track resulting in momentary loss of tyre contact and excessive instantaneous loads on suspension and chassis Dead shock on one corner • A dead shock is surprisingly difficult for a driver to identify and/or isolate • At the rear, that car will ‘fall over’ onto the outside tyre and oversteer in one direction only • At the front, the car will ‘fall over’ onto the outside tyre on corner entry and then understeer. WHEEL ALIGNMENT Front toe-in: too much • Car darts over bumps, under heavy braking and during corner entry – is generally unstable • Car won’t point into corners, or if extreme. May point in very quickly and then dart and wash out Front toe-out: too much • Car wanders under heavy braking and may be somewhat unstable in a straight line, especially in response to single wheel or diagonal bumps and/or wind gusts • Car may point into corners and then refuse to take a set • If extreme will cause understeer tyre drag in long corners Rear toe-in: too little • Power on oversteer during corner exit Rear toe-in: too much • Rear feels light and unstable during corner entry. Car slides through corners rather than rolling freely Rear toe-our: any • Power oversteer during corner exit and (maybe) in a straight line • Straight line instability Front wheel caster or trail: too little • Car too sensitive (twitchy?) • Too little steering feel and feedback Front wheel caster or trail: too much • Excessive physical steering effort accompanied by too much self return action and transmittal of road shocks to the drivers hands • General lack of sensitivity to steering input due to excessive force required Front wheel caster or trail: uneven • Steering effort is harder in one direction than in the other • Car will ‘pull’ towards the side with less caster – good on ovals, bad on road courses Camber: too much negative • Inside of tyre excessively hot and/or wearing too rapidly. At the front this will show up as reduced braking capability and at the rear as reduced acceleration capability. Depending on the racetrack and the characteristics of the individual tyre, inside temperature should be 10°-25° hotter than the outside. Use a real pyrometer with a needle rather than an infra red surface temperature device. Camber: not enough negative • Outside of tyre will be hot and wearing. This should never be and is almost always caused by running static positive camber at the rear in an effort to avoid the generation of excessive negative camber under the influence of aero download at high speed. • A better solution is improved geometry and increased spring rate. Dynamic positive camber will always degrade rear tyre performance and if extreme, can cause braking instability and/or corner exit oversteer. Bump steer, front: too much toe-in in bump • Car darts over bumps and understeers on corner entry Bump steer, front: too much toe-out in bump • Car wanders under brakes and may dart over one wheel or diagonal bumps • Car may understeer after initial turn in Bump steer, rear: too much toe-in in bump (same as solid axle steer on outside wheel) • Roll understeer on corner entry • Mid phase corner understeer • ‘Tiptoe’ instability when trail braking • Darting on power application on corner exit Bump steer, rear: too much toe-out in bump (same as solid axle steer on outside wheel) • Instability on acceleration • Good turn in followed by a tendency to oversteer at mid-phase and exit TYRES Too much tyre pressure • Harsh ride, excessive wheel patter, sliding and wheel-spin • High temperature reading and wear at the centre of the tyre Too little tyre pressure • Soft and mushy response • Reduced footprint area and reduced traction • High temperatures with a dip in the centre of the tread Front tyres ‘going off’ • Gradually increasing understeer – Enter corners slower, get on power earlier with less steering lock Rear tyres ‘going off’ • Gradually increasing power on oversteer – Try to carry more speed through corner and be later and more gradual with power application LIMITED SLIP MALADIES Limited slip differential wearing out • Initial symptoms are decreased power on understeer or increased power on oversteer and inside wheel spin. The car might be easier to drive, but it will be slow • When wear becomes extreme, stability under hard acceleration from low speed will diminish and things will not be pleasant at all Excessive cam or ramp angle on coast side plate (clutch pack) limited slip differential • Corner entry, mid-phase and corner exit understeer. Incurable with geometry changes or rates – must change differential ramps. In 1998, virtually everyone is running 0/0 or 80/80 ramps. SUSPENSION GEOMETRY Excessive front scrub radius (steering offset) • Excessive steering effort accompanied by imprecise and inconsistent ‘feel’ and feedback Excessive roll centre lateral envelope: front or rear • Non-linear response and feel to steering input and lateral ‘G’ (side force) generation Rear roll centre too low (or front r/c relatively too high) • Roll axis too far out of parallel with mass centroid axis, leading to non-linear generation of lateral load transfer and chassis roll as well as the generation of excessive front jacking force. • Tendency will be towards understeer Rear roll centre too high (or front r/c relatively too low) • Opposite of above, tending towards excessive jacking at the rear and oversteer Front track width too narrow relative to rear • Car tends to ‘trip over its front feet’ during slow and medium speed corner entry, evidenced by lots of understeer (remember trying to turn your tricycle?) • Crutch is to increase front ride rate and roll resistance and increase the camber curves in the direction of more negative camber in bump (usually by raising the front roll centre) INSTABILITY Straight line instability: general • Rear wheel toe-out, either static due to incorrect (or backwards) setting, or dynamic due to bump steer or deflection steer • Vast lack of rear download or overwhelming preponderance of front download • Wild amount of front toe-in or toe-out • Loose or broken chassis, suspension member or suspension link mounting point • Dead shock absorber Straight line instability: under hard acceleration • Malfunctioning limited slip differential • Insufficient rear toe-in • Deflection steer from rear chassis/suspension member or mounting point • Rear tyre stagger (car pulls to one side) • Dead rear shock absorber • Wildly uneven corner weights Straight line instability: car darts over bumps (especially one wheel bumps) • Excessive Ackermann steering geometry • Excessive front toe-in or toe-out • Uneven front caster or trail settings • Insufficient rear wheel droop travel • Dead shock or uneven shock forces or incorrectly adjusted packers/bump rubbers • Wildly uneven corner weights • Front anti-roll bar miles too stiff Instability under hard braking: front end wanders • Excessive front brake bias or uneven corner weights or excessive front damper rebound force Instability under hard braking: car wants to spin • Excessive rear brake bias • Insufficient rear droop travel • Wildly uneven corner weights • Excessive rear damper rebound force • Unbalanced ride/roll resistance – too much at rear • Insufficient rear camber (usually in combination with one or more of the above) RESPONSE Car feels generally too heavy and unresponsive • Tyre pressures too low • Insufficient ride and/or roll resistance (springs and bars) • Excessive aerodynamic download, or insufficient spring for the amount of download • If high speed acceleration is sluggish, the culprit is often too large a rear wing Gurney lip Car feels sloppy, is slow to take a set in corners, rolls a lot, doesn’t want to change direction • Insufficient tyre pressure • Insufficient damper forces • Car too soft in ride and/or roll Car responds too quickly – has little feel – slides at the slightest provocation • Excessive tyre pressure • Excessive bump force in shock absorbers • Car too stiff for inexperienced driver • Excessive ride or roll resistance • Excessive front or rear toe-in • Insufficient aerodynamic download UNDERSTEER Corner entry understeer: car initially points in and then washes out • Excessive toe-in or toe-out (car is usually ‘darty’) • Insufficient front droop travel (non droop limited cars only) • Incorrectly adjusted packers (car rolls on to packers) • Insufficient front damper bump resistance (similar to roll stiffness example) • Insufficient front roll stiffness – car may feel like it is pointing in but may actually be falling over onto the outside front tyre due to insufficient front roll stiffness or diagonal load transfer under heavy trail braking. Initial understeer can often be cured by increasing front roll resistance, even though doing so may increase the amount of lateral load transfer. • Non linear lateral load transfer due to spring and/or bar geometry. Or to non-optimal roll axis inclination Corner entry understeer: car won’t point in and gets progressively worse • Driver braking too hard, too late • Relatively narrow front track width • Excessive front tyre pressure • Excessive front roll stiffness (spring or bar) • Relative lack of front download (excessive rear download) • Incorrectly adjusted packers or bump rubbers (car rolls onto packers) • Insufficient front toe-in • Insufficient Ackermann effect in steering geometry • Front roll centre too high or too low • Insufficient front damper bump force • Insufficient front toe-out • Insufficient front wheel droop travel (on non droop limited cars only) • Nose being ‘sucked down’ due to ground effect • Excessive Ackermann steering geometry • Can also be caused by unloading the front tyres due to rearward load transfer under acceleration – cures include: • Increasing front damper rebound force • Increasing rear damper low speed damper rebound force • Increasing rear anti-squat • Droop limiting front suspension (will also make turn in more positive and will reduce overall understeer) Mid-corner (mid-phase) understeer • Excessive front tyre pressure • Excessive relative front roll stiffness • Excessive front toe (in or out) • Excessive Ackermann steering geometry • Insufficient front dynamic camber • Relatively narrow front track width • Insufficient front wheel travel (car rolls onto packers or bottomed shock) • Insufficient droop travel (on non droop limited cars) Corner exit understeer: slow corners • Often a function of excessive corner entry and mid-phase understeer (whether driver induced or car induced) followed by throttle application whilst maintaining the understeer steering lock. The first step must be to cure the corner entry and mid-phase understeer. If this is impractical, then corner entry speed should be reduced slightly in order to allow earlier throttle application. Sometimes we have to be patient. Corner exit understeer: fast corners • Relative lack of front download – often caused by negative pitch angle (squat) due to rearward load transfer on acceleration. Can be helped by increasing rear anti-squat and/or by increasing rear low speed bump force, increasing front droop force and by limiting the front suspension droop travel. • Relatively narrow front track width • Excessive ramp angle or pre-load on clutch pack or plate type limited slip differentials. Understeer stronger in one direction than in the other • Uneven corner weights • Uneven caster • Uneven camber (especially front) OVERSTEER Corner Entry Oversteer • Excessively heavy trail braking • Excessive rearward brake bias • Severe rearward ride rate/roll resistance imbalance • Rear roll centre too high • Diabolical lack of rear download • Severely limited rear droop travel • Broken or non-functioning outside rear damper • Broken or non-functioning front anti-roll bar Note: A slight feeling of rear ‘tiptoe’ type hunting on corner entry can be due to excessive rear toe-in or excessive rear damper rebound force. Mid-corner (mid-phase) oversteer • Driver threw the car at the corner to get through initial understeer – only cure is to educate the driver and/or decrease understeer • Excessive rear tyre pressure • Excessive relative rear ride and/or roll stiffness • Rear suspension bottoming in roll • Insufficient rear droop travel (non droop limited cars only) • Very loose rear anti-roll bar linkage Corner exit oversteer: gets progressively worse from the time the power is applied • Worn out limited slip differential • Excessive anti-squat geometry • Excessive rear ride and/or roll stiffness • Insufficient rear spring, bar or shock (low piston speed bump force) allowing the car to ‘fall over’ onto outside rear tyre • Excessive rear negative camber • Too little dynamic rear toe-in • Relatively insufficient rear download Note: If car feels as though it is sliding through the corner rather than rolling freely, reduce the rear toe-in and see what happens. Corner exit oversteer –sudden – car seems to take a normal exit set and then breaks loose • Insufficient rear suspension travel (lifting the inside wheel on non droop limited cars or bottoming the outside suspension due to lack of bump travel) • Incorrectly adjusted packers • Dead rear damper • Sudden change in outside rear tyre camber • Too much throttle applied too soon –often after the drivers confidence has been boosted by the car taking a set. Car does not put the power down smoothly on the exit of smooth corners • Worn out limited slip differential • Excessive rear ride/roll resistance • Excessive anti-squat geometry • Excessive rear tyre pressure • Tyres gone • Excessive rear damper low piston speed bump force • Excessive rear dynamic camber – either from download or from camber change on squat • Relative lack of rear download Car does not put the power down on the exit of bumpy corners • Any or all of the above for smooth corners • Excessive rear damper high piston speed force • Excessive rear damper rebound force (jacking down) • Insufficient rear droop travel TRANSITIONS Understeer in, snap to oversteer on power application • The most common complaint of all ! Usually caused by too little roll resistance – car falls over on entry and then snaps. • Increase front bar and/or spring and/or front damper low piston speed bump force. Stiffening the bar will also transfer some load on to the inside rear tyre on acceleration. • If the suggestion above cures the understeer but the car still snaps, the culprit is almost always the car falling over on the outside rear tyre on longitudinal plus lateral load transfer. Add rear bar or spring. Bar will transfer load away from the inside rear tyre. Spring will not. Spring will, however, decrease traction over exit bumps while bar will not. • Loose anti-roll bar linkage/blade sockets can have the exactly same effect Car is slow to change directions in chicanes or esses • Insufficient ride/roll stiffness, especially at front. • Relatively narrow front track width. • Insufficient front damper low piston speed bump force. BRAKES Brake pedal gets soft, spongy and/or long during session or race • Fluid boiling in calipers. Not pad fade ! Upgrade fluid and/or cool calipers. Brake pedal is soft, spongy and/or long before the car is run • Air in the system – bleed brakes. • Brake pads badly taper worn – replace Reduced stopping power with normal brake pedal • Pad fade – due either to unbedded new pads or to temperature beyond pad capacity. Upgrade pads. Long pedal with little effort required • Master cylinder(s) too small or pedal mechanical advantage too great. Rough braking – pedal vibrates under pressure • Organic pickup on discs – clean discs with garnet paper (not aluminium oxide sandpaper) and upgrade pads • Warped (not grooved) rotors. Grind (or, if you must, turn) rotor surfaces • Insufficient axial float on floating discs Uneven braking – car pulls to one side • Stuck piston(s) – rebuild calipers Brake bias changes during application • Excessive clearance between master cylinder push rod clevises and bias bar bearing housing. • Rod end bearings used instead of clevises on master cylinder push rods. • Bias bar incorrectly adjusted. Bar must be perpendicular to vehicle longitudinal axis with full foot pressure applied. Contrary to popular opinion, relative length of master cylinder pushrods is immaterial. -
Massive Understeer At The Track, What To Do?
xr_velocity replied to xr_velocity's topic in Wheels and Tyres
INitgial thoughts on the rear sway bar removal....feels weird compared to wit hit on , but only because it is different. Definitely a lot more squat to the outer rear during power down out of a corner, quite a weird sensation feeling the weight transfer so quick. Might actually be good for my understeer given the weight more easily moves to the back. Can't comment on mid corner entry and mid corner....just too stupid to give it hell on the street. Will keep it off for a few more days then put it back on again to gauge how well it turns in and holds the front in line during a corner. -
Massive Understeer At The Track, What To Do?
xr_velocity replied to xr_velocity's topic in Wheels and Tyres
I measured the car height today, rear was 340mm hub to guard...front was 325mm hub to guard. Way too low in the front. The rear is good going by other people's reports and general consensus on how high / low these things perform best at. The Lovells front SL springs have sagged over time so it's time for them to go. I have ordered a set of King Spring KFFL-57/520 front springs. They are the 520lb springs, which is up from 410 I have in the Lovells fronts. I spoke to King Springs today, their standard front BA/BF springs (the ones not coded with 520) are only 375lb which again would have been too soft, softer than the Lovells if the figures are correct. The 520lb King Spring I was told by Kins Springs should sit at 365mm height, but in reality looking at other people's experiences with that spring in an XR6T, should be closer to 355-350mm which is right where I want it. I don't need to change the rear Lovells springs as they are already rated at 370lb, where as the King Springs KFRL-68SSL is rated at 360-380lb and possibly a little higher as it is a progressive spring rate meaning it gets firmer as it compresses. I think the spring rates go some way to explaining what was happening to my car. The soft fronts were compressing too much and taking a lot of weight transfer onto the outer front in a corner. The firmer (in comparison to the front) rear springs were holding the back quite steady which was again putting weight to the front, then throw in the firm front sway bar which was promoting more understeer. If the front spring change fixes my woes, I will be a happy man. If not I will try something different. I have removed the rear sway bar today, will be doing some on road feeling around to see how it goes. I have a track day coming up on the 30th of September so will get to test out my new front springs. I will take the tools I need to remove the front sway bar on the day to gauge how it feels with one and without one. But I will start the day with it on as I need to gauge the difference the front springs make. Two changes will leave me with no idea what did what. Picking up some 328mm PBR brakes this week along with Ferodo 2500s in the front Brembos...that way hopefully my rear brake pads don't turn into crushed biscuits after 1 hour on the track again! -
Unfortunately not.
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Massive Understeer At The Track, What To Do?
xr_velocity replied to xr_velocity's topic in Wheels and Tyres
Just called Heasmans. Given that I have the idea in mind to keep the car street oriented first and foremost for the time being, suggestion was some Bilsteins and King 520lb springs in the front and leave the 370lb Lovells rear springs in there. Try get a bit more camber with an adjustment kit as well. Leave rear alignment as is though as I am happy with it. Their thought was that the fronts are just too soft for a heavy car with a lot of nose weight...which is something I was considering already, but didn't want to have to do :( I think my next step from here will be to get a set if Kings front and rear because I want to raise the car anyway, sick of scraping things under the car! I will persist with the Lovells shocks for now and see how that goes.The Lovells springs are the SL and SSL ones from memory. I think I should have gone with standard and SL. I will take the rear sway bar off this weekend to see how it feels on the road and gauge whether or not I may like it at the track...without going silly of course. -
Massive Understeer At The Track, What To Do?
xr_velocity replied to xr_velocity's topic in Wheels and Tyres
Thanks all. I know it is not a sports car, but the understeer really is shocking, not normal at all. I know some of this is driver ability for sure. I was actually about to call Heasmans today, didn't get time...though will do so tomorrow. Is still want the car road drivable, so it can't be super firm, needs to behave in the wet etc. I am after a compromise that is fairly neutral. -
Massive Understeer At The Track, What To Do?
xr_velocity replied to xr_velocity's topic in Wheels and Tyres
No worries, 30mm and 22mm at a guess. -
Massive Understeer At The Track, What To Do?
xr_velocity replied to xr_velocity's topic in Wheels and Tyres
Here is a pic of my car on a 90 degree turn at EC. See all the weight on the front outer tyre....my understeer problems in a nutshell. That is one corner I just cannot get around without completely backing off. Got to get the weight off the front of the car. -
Massive Understeer At The Track, What To Do?
xr_velocity replied to xr_velocity's topic in Wheels and Tyres
What sway bar sizes are you using? -
Massive Understeer At The Track, What To Do?
xr_velocity replied to xr_velocity's topic in Wheels and Tyres
http://stealthtdi.com/SwayBars.html This sums up how to fix your issue of lifting a rear wheel. -
Massive Understeer At The Track, What To Do?
xr_velocity replied to xr_velocity's topic in Wheels and Tyres
You should be worried about lifting a rear tyre off the road, you'll never get as much grip from one wheel as two. It's the stiffness somewhere on your rig that is causing the rear wheel to lift, alignment will do nothing for you until you can get the wheel to stay on the ground. -
Massive Understeer At The Track, What To Do?
xr_velocity replied to xr_velocity's topic in Wheels and Tyres
http://www.trackpedia.com/wiki/Suspension There are some good explanations here about sway bars and stiffness..."When cornering, the bar will twist with the outside end being pushed down, and the inside end being lifted (just like the body of the car). On the outside tire, this downward pressure helps increase tire traction. However, on the inside tire, the anti-roll bar is pushing up on the suspension reducing the downward force the spring is trying to place to keep the tire on road. If the anti-roll bar is too stiff, it will overpower the spring, prevent it from extending enough to keep the tire on the road, and the wheel will actually lift off the ground. This is not an optimum situation, but it is common in several racing classes. The cause is not so much poor engineering, but the limitations of the class rules that allow the engineer to compensate for it." Could be your scenario. The Teins are already pretty stiff so adding some VERY stiff roll bars for this car and you have problems...which you are seeing now. -
Massive Understeer At The Track, What To Do?
xr_velocity replied to xr_velocity's topic in Wheels and Tyres
Alignment won't keep your rear trye on the ground. Are you sure the rear is lifting? It sounds odd that it would be doing that at all. If your inside rear is lifting off the ground that means your outside front has to be almost at full compression...since you have a 30mm sway bar on front that is odd, hence my question are you sure your rear is lifting. It would be hard to get that much roll in a car with such stiff sway bars. Are you referring to being on the brakes and coming into a corner which would make your outside front compress?