Typical timing for street cars at Sepang SIC

[cqloh]

soulV.. don't be disappointed with your decision having said all i have about the 1.5 way.

racing is about an entire package.. sometimes you make the right decisions.. sometimes you don't.. but instead of crying over something you probably don't have the resources to change (money, availability and more importantly time) you almost always have to live with it.

the philosophy behind building a race car (at least what i adopt) is to suit the car to the driver.. but we don't live in a world where everything goes your way.. so its a chance for you to suit your driving to the car.

since i'm not a driver like faisal or adian i can hardly explain the details in which you will experience with your setup ie. what line to take, when to brake and how much throttle to apply or remove...
what i can tell you from an engineering point of view is that with a 1.5 way (all other settings being the same camber, alignment, ride height etc) is that the car becomes sensitive in pitch.. that is the weight transfer for an aft of the car in a corner.. you need to balance the car with throttle and brake application; as i said above.. the amount of lock with the gas applied is the same.. it only happens when you are off the gas when the weight is transfered from the rear to the front..

when you get off the gas abruptly.. the weight is transfered quickly from the rear which overloads the front tires and causes the maximum LSD locking ability.. if you allow the weight to transfer in a smooth controlled manner the locking is reduced.
unless you know someone that has the experience and know how to set the preload on your LSD.. thats probably the best advice i can give you..

again it boils down to skill.. so practice practice practice..

 

[adian]

cq... nice. I am not an actual engineer so your explanation is a good one. I understand the basic intricacies of all these components, but not specific workings nor the physic behind them, so I very much appreciate and understand your write up. Thanks!

 

[soulV]

thanks cqloh for the write up...but then it trigger me to a new question...can the lsd preload be changed/set?for what?& the effect of changing the set up?

thanks again..

 

[cqloh]

adian.. hahah you're very welcome.. its always good when a driver appreciates an engineeres explanations.. they usually shrug and say "i just know how to drive"...

soulV.. LSD preload can be set on clutch type LSDs..well.. they also can be set for torsen and viscous.. but thats totally beyond our capabilities...
on the clutch type.. preload is set with springsthat push against the clutch packs of the lsd..
by changing preload.. you change the way the LSD bites... either abrupt or in linear fashion..

as with the example above.. if you reduced the preload in your lsd... you wouldn;t have to be gentle with the throttle control... the lsd would have done it for you by slowly loading up the tires.

 

[adian]

soulv/cqloh: yes, you can change the preload, but your 1.5 way setting is fixed, and that cant be changed unless you change to a different LSD casing! The best thing you can do right now SoulV is to get your LSD serviced and reduce the preload a bit as advised by Cq. That way it should be more progressive in relation to your driving.

Bump: soulv/cqloh: yes, you can change the preload, but your 1.5 way setting is fixed, and that cant be changed unless you change to a different LSD casing! The best thing you can do right now SoulV is to get your LSD serviced and reduce the preload a bit as advised by Cq. That way it should be more progressive in relation to your driving.

 

[cqloh]

thats a good one adian... something i completely neglected..

soulV: if you've purchased a 2nd hand LSD the first thing i want you to do is to jack the car up on one side so the other front wheel is on the ground. if possible remove the wheel thats in the air and use a torque wrench to turn the 32mm drive shaft locking nut. you should have something within the vicinity of 50-65 Newtons..

if you don't have access to a torque wrench then try turning the wheel with your hands.. if it turns easily then its time to rebuild the LSD...

what you are describing are also symptoms of a worn or broken LSD...

if its not then breathe a sigh of relief and continue driving like a pro =)

 

[adian]

What about basic alignment and geometry setup fellas? Do you fiddle with that before a track day? It makes a huge difference, you'll be surprised! What do you guys set up?

I know it's "the in thing" to have lots of front static camber, but in reality it's not ideal. The more camber you run, the less traction you have under-braking, and also reduced steering response into the corner. There's a balance la. For road-cum-track day cars I wouldnt go more than -2deg. If you hardcore can try la -3deg.

Rear toe I personally like it to be zero. Some ppl use toe-out but I dont like that the car takes a little bit more wasted time and opposite-lock to straighten out compared to zero toe.

If you have adjustable height suspension, dont take for granted whatever height the foreman put for you. It's always best to start with a flat car ie front and rear rideheight the same. Raising the rear slightly (up 10mm) increases understeer, and lowering is vice-versa. OR you can raise the front or lower it, it's opposite of the rear (Raise front slightly to reduce understeer). There is a point tho where altering the ride height too drastically will create problems. Remember to get this set right for good cornering balance!

And of course you can also play with tyre pressures.

Tyre pressures can alter the balance a lot if you get it right. Plus, what works on the 1st lap out will not be the same by your 5th lap. So when you 'tuned' your tyre pressures, have a target at which lap you'd prefer them to be at their best response. Usually on track days most ppl only go out for 5-7 laps max and then come in for a rest (as you drive road cars and dont want to break em!), so tuned for optimum handling balance from Lap 3 till about Lap 5, and when it starts crapping up on Lap 6, you can come in to the pits :)

FWD cars can get away with high rear tyre pressures eg 2-3psi higher than normal, and you'd want to be 1-2psi lower than normal at the front. Of course this depends on the brand and type of tyre. Ideally you want a bit of 'looseness' at the rear for an FWD car, and not want to 'lean' on the front tyres so much that they overheat and you start understeering.

FR cars could do with 1-2 psi extra in the front tyres, and MR cars start with more or less equal pressures front and rear. This is just a guideline, you can "tune" as you go along. Just be sure you are driving consistently!

For all the hundreds and thousands of $$$ you spend on modding, just a few tens of ringgit getting the setup right can make or break 1-2seconds per lap!

/adian

 

[cqloh]

well said again adian...

just a few quick pointers.. always check your alignment before and after a track day.. alignment especially on street cars tend to run away from your initial settings, we check alignment on our track cars every time it sees the track to ensure that all our changes reflect the true results.

i'd personally prefer running 0 toe front and rear as this will reflect the true character of the car and tires, then progressively make changes. i never run toe out in the rears unless the car has compliance bushes built in (DC5s and FC RX7s take note) but as with all cars.. theres give and take.. if you run toe out.. you car will be unstable in the straights and tend to oversteer into a corner.. on rwd cars when the power is applied its gonna be a hand full..

buy a good tire pressure gauge and make sure you take the pressure when its hot. ensuring that all 4 have the same pressures.

but i have to argue the point regarding raising and lowering of the front and rears... maybe we'll save that for another day.

what is also important is that you log all your changes so you know what you're doing and where you're heading in terms of set up.

 

[minivan]

I usually set 0 toe all round and as i'm a road car i set just -1 to -1.5 camber all round. As for tyre pressure, i just set higher than normal by 2-3psi all round. But this one huh, some people say set lower then normal as the tyre temp will spike when the tyres are hot. I've tried it before, but the car understeers even worst and it feels loose and it scrubs the tyres' wall quite badly... so, i'm comfortable with setting higher pressure for trackdays...

 

[km_chew]

but i have to argue the point regarding raising and lowering of the front and rears... maybe we'll save that for another day.

I'm following up on this thread very closely, eager to know about this part. Free to explain more ? This kind of technical knowledge really helps to interpret a lot of When / How / What / Where for me ..

Thanks again to CQ / Adian. You guys are helpful.

 

[soulV]

hmm...

Bump: hmm...

Bump: hmm...

 

[adian]

Minivan: Well said. This is because different types and brands of tyres react differently. Some tyres work best at 35psi hot, some best at 32psi hot, etc.

CQ: Re raising and lowering the ride height, not correct meh? I have always started setting up with a flat car, measured from wheel centre hub. And for track and drifting I always try to dial in something lower at the rear by 5-10mm, as it helps a lot braking deep into the turns, and i'm able to achieve a better balance point.
I do know however that raising the front a by too much promotes 'push', and the opposite for the rear. You're explanation, when you have the time, is most welcome!

Basically, everyone talks about power and GT wings and AD08 tyres, but very very often I notice some ppl never bothered to work on the basic geometry setups! Basically, reducing lap times for almost free :)

Bump: Minivan: Well said. This is because different types and brands of tyres react differently. Some tyres work best at 35psi hot, some best at 32psi hot, etc.

CQ: Re raising and lowering the ride height, not correct meh? I have always started setting up with a flat car, measured from wheel centre hub. And for track and drifting I always try to dial in something lower at the rear by 5-10mm, as it helps a lot braking deep into the turns, and i'm able to achieve a better balance point.
I do know however that raising the front a by too much promotes 'push', and the opposite for the rear. You're explanation, when you have the time, is most welcome!

Basically, everyone talks about power and GT wings and AD08 tyres, but very very often I notice some ppl never bothered to work on the basic geometry setups! Basically, reducing lap times for almost free :)

 

[soulV]

hmm...another question to ponder..

 

[akuma]

1 more thg i'd like 2 add..BRAKES!very important component too 4 track days....might need 2 spend a lil more but w better brakes....u tend 2 brake later n also more consistent......+ on a lightweight car like my EF CRX..heheee.....i can brake @ almost d 50M mark on d main straight n continue doin so for 4-5 laps...no brake fade @ all......
oh,btw,i'm running EBC Red Stuffs front w Brembo slotted rotors n EBC Green Stuffs rear w stock rotors.....front camber -2.5deg,rear -1.5deg....195/55/15 AD07..my laptime?dun ask...d only time i my passenger "managed" 2 time me,i did a 2.56:xx...chis!hahahahahah

 

[soulV]

thanks akuma...very gud info...thinking of using kinda like ur set up as a base bef getting my own since we drive similar car.....:proud:

whats the price for those ebc stuff? where to get?