Front Roll Bar settings...help!

[Motormouth]

Looking for a bit of help here guys.... I was testing a Global GT Light at Mondello today and through the quicker corners (turn two and the second part of the esses if you know the circuit), the car was very tail happy and kept snapping out of line, giving me no alternative but to lift. I went one notch stiffer on the front roll bar and this made a huge difference. As soon as I went back out, I could take both those corners flat, or almost flat.
The problem is that the stiffer front bar means I now can't get turned into the slow stuff, and unless I go in slower then before, I miss the apex. I know the cars have a solid rear axle and will tend to push on anyway because of this, but the bar definitely made it worse.
My times were quicker with the bar stiffened but I know It's costing me time in the slow ones. So, what to do next?
Any help/advice appreciated............

[kelvin88]

progresive springs?

[phoenix]

Make the front bar adjustable from the cockpit......

[GordonG]

fit a diff?

[GordonG]

slightly more practical, try playing with the shocks - stiffer at the back, or softer at the front. You may find that there is more shock movement going on at turn in to a tight corner than in a fast sweeper, which allows you to differentiate performance in the 2 types of corner.

You may find though that it makes it looser (more OS) over bumps.

G

[zefarelly]

interesting. . . I sufferedthe same old understeer problems at Spa last weekend andwatched the Lotus cortinas powering round with a wheel in the air, I think a 1" ARB is too much and 7/8" is the norm, but also with stiffer springs, 600lb instead of 550. . . . I have the same rigid rear axle and the car was fine through blanchemant (flat if the lines right) and twitchy but ok at Eu Rouge nearly flat out!

I'm sure dodgy brakes don't help in as much as I carry too much speed into the tighter corners, but the car turned in ok then just drifted away at the front, I thought I'd cured the problem but it seems to be back, possibly oil on the circuit made matters a bit worse but not that much

[AU N EGL]

Sounds like the challange of a race course. Some corners are great some or so slow a snail could be faster.

The question is, which provides the quickest laps with the lowest lap times?

That is the setting you want.

[zefarelly]

a bent drag link probably isn't helping my steering geometry either !

[Lukin]

There are a few things you could do (Without knowing your car it's hard to say).

Aero vs Mechanical grip. If you can add more rear aero you can come back on the FARB to help in the slow corners where aero contribution is low, but still get decent rear grip in the quicker corners. For a basic car this is probably the easiest.

Front Geometry. Lowering the front roll centre will help give more front grip at the entry to middle of the corner and can take out some of the initial response in quicker corners (if that was the drama). Of course if the oversteer is mid corner, then it could hurt. Also anti-dive can help in slow corners as the brake is released with minimal effects in quicker corners (which would have less brake)

Shocks - Im with Gordon, play with the shocks if you can. Shocks can sometimes hurt in situations when you think they would help. For slow corners (which implies heavy braking) increasing the rear rebound will help the braking and turn-in while in quicker corners (with less pitch) it may not be as sensitive. Front shock is a hard one, it depends on so many things.

[Motormouth]

This is great stuff guys, thanks. I'm learning all the time. I know my way round an fwd saloon pretty well but it's a while since I tried to adjust a rwd chassis.
I wonder if a bit of toe-out would help the Cortina? Tends to help when you get mid-corner washout.......

[Lukin]

Yeah that sounds good.

I assume the rear toe's in? A little more of that could give some rear stability too, though it's hard to tell without having a prior knowledge of tyres/chassis etc.

With the softer RARB, where did it go OS in the corner (as you pick the throttle up, or mid corner, or entry etc)?

With the FARB up, where is the main US? Is there initial response when you steer (which I've found can be the case with FARB up; it gives initial response and turn but then overloads the tyre mid corner) then it washes to the middle of the corner or is straight away (no response and no mid grip)?

[Motormouth]

In he Global, with the FARB (noe I have the lingo!!) full stiff (one up) It is initial turn in, or lack of, that is the problem. Once it is eventually turned in, the throttle will adjust the cars' attitide easily!!

[zefarelly]

exactly the opposite of me, initial turn in is great but then fades away, I suspect If I carried less speed in and nailed it at the apex I could push the car round with my right foot, BUT being a relatively low powered car momentum is everything!

[GORDON STREETER]

In the end all suspension settings can only be a compromise (if not cockpit adjustable) and its best to set the car up for the faster corners, the slower corners you can still take the racing line and people cant just overtake you easily.
All that most clubbie racers can do is set the car up to get on the fastest lap possible for the class that they are in. Most cars that put in good times understeer on slow corners and you have to adapt your driving style and line to suit.
Other factors come into play like tyres going off at different rates front to back, especially in longer races and playing about with pressures can reap benefits. At the end of the day an oversteering car is more difficult to drive than a neutral to understeering one.

[zefarelly]

tyre pressure for me do make a big difference, the DUnlop crossplies go right off if they get too hot, they go up 3-5 PSI when in use, depending on the weather

I guess I need to learn to slow down better for slow corners and gain exit speed for the big/quick ones as Blanchemant flat, Eu Rouge (nearly) flat and La SOurce/Rivage with understeer isn't so bad. certainly preferable to the other way round!

[GORDON STREETER]

One thing I have found with ARBs is that when you have found an optimum diameter one for your particular car, make the adjustment stepless rather than a series of holes as you can tune it easier and quicker. Also if you use a thick diameter bar its even more important as it only has to be moved a slight amount to make the difference.

[phoenix]

Originally Posted by GORDON STREETER

One thing I have found with ARBs is that when you have found an optimum diameter one for your particular car, make the adjustment stepless rather than a series of holes as you can tune it easier and quicker. Also if you use a thick diameter bar its even more important as it only has to be moved a slight amount to make the difference.

Definitely. Another thing people may not realise is that the bar gets exponentially stiffer for every adjustment. Say you have holes and they are, for example, 20 mm apart. Starting with the bar in the softest position, moving to the next position will make the bar stiffer, but the same increment to the third hole will make much more difference than the move from the first to second holes.

For the same reason, longer lever arms on a thicker bar allow finer adjustment than short lever arms on a thinner bar.

[zefarelly]

with fixed positions then I'm F***ed although running a 1" ARB and 500lb springs seems less popular on LC's so I'm switching to 7/8" ARB and 600lb springs for testing next

[Motormouth]

Doesn't look like she's understeering too much in your avatar pic!!!!