Got a track related question? I'll try to answer.

[brn12345]

Originally Posted by Doozer

Hey folks,

Experiencing understeer on entry in long sweepers and can't break the rear free throughout the rest or the corner. Really, really frustrating.

Considering an upgrade to a 1.5 diff to try and get a little more free on entry and solve this dilemma.

Curious to hear some racers thoughts on if a diff *could* solve this issue (may very well be a driver issue, not sure).

There seem to be some different thoughts on diff preload as well. Some say lower is better, others more. Anyone play around with this and feel like commenting?

Thanks in advance

You would need to state your full setup to get a useful answer. Include suspension brand and settings (ride height, compression, rebound), alignment specs, wheels and tires (width, diameter, offset, pressure), also list any other suspension and handling parts you have installed.

[Doozer]

Originally Posted by brn12345

You would need to state your full setup to get a useful answer. Include suspension brand and settings (ride height, compression, rebound), alignment specs, wheels and tires (width, diameter, offset, pressure), also list any other suspension and handling parts you have installed.

Good god, long list. Here goes:

Ohlins 380lbs spring ft and rear
3 clicks hard rear
8 clicks hard front
Cusco fender braces
Tanabe lower front sub brace
Toyota hardend frame bolts
Whiteline 22mm front sway (set loose)
Whiteline 18mm rear (set medium)
Whiteline rear sub bushing (full bushing)
CF drive shaft
JP auto works A/T vacuum delete
5:1 FD
Airaid intake
Delicious tune
ACE 4-2-1 header and front pipe
RacerX front LCA's (solid bushings)
RacerX rear UCA's
RacerX rear LCA's
TRD door latches
front caynards
Perrrin steering rack bushings
Hardrace stiff motor mounts
Rays 17x8.5 SL's (37et)
20mm spacers rear only
Maxxis RC-1 235/40/17
AP 5200 Sprint kit (ft only)
CL-6 sintered pads (ft and rear)
Essex "harness" bar
51.3% cross weight
45% rear weight
5.6 caster LF (I forget, have to check notes)
5.5 caster RF (I forget, have to check notes)
4* camber LF
2.5* camber RF
4* camber LR
2* camber RR
2mm toe out front
0 toe rear
57cm ride height LF (measured from center of hub to fender with driver (78kg)
57cm ride height RF
57.7cm ride height LR
57.5cm ride height RR
total weight 1218.6kg with driver (2681lbs)

looking to solve T3 (second right after straight ending under bridge)
[ame="https://www.youtube.com/watch?v=zHM51jTFXu0"]3 22 '15 OTGP Time Attack Final - YouTube[/ame]

that's all I can think of right now
thanks

[ddeflyer]

Originally Posted by Doozer

Hey folks,

Experiencing understeer on entry in long sweepers and can't break the rear free throughout the rest or the corner. Really, really frustrating.

Considering an upgrade to a 1.5 diff to try and get a little more free on entry and solve this dilemma.

Curious to hear some racers thoughts on if a diff *could* solve this issue (may very well be a driver issue, not sure).

There seem to be some different thoughts on diff preload as well. Some say lower is better, others more. Anyone play around with this and feel like commenting?

Thanks in advance

Generally speaking, a diff is unlikely to be the solution you want now (it is possible it could be the solution, but if it was then you would probably not be asking). Quite frankly, the most common cause of understeer on entry is not slowing down enough for your inputs (if so, some people might be able to do a faster entry but they have technique that you don't yet).

The first question I ask myself when I am figuring out understeer on a corner is how much of the rear tires I am using at that point (and if there is a reason I'm not using more). Usually I find that I am not making good use of of the rear and I need to adjust how I have the car balanced at corner entry (usually using the throttle). So my question for you is: "Hows your throttle steering? Do you dance on the throttle through the corner or is it an on off switch?"

[7thgear]

why is your front toe out, and your L/R camber off by so much

[ddeflyer]

Originally Posted by Doozer

Good god, long list. Here goes:

Ohlins 380lbs spring ft and rear
3 clicks hard rear
8 clicks hard front
Cusco fender braces
Tanabe lower front sub brace
Toyota hardend frame bolts
Whiteline 22mm front sway (set loose)
Whiteline 18mm rear (set medium)
Whiteline rear sub bushing (full bushing)
CF drive shaft
JP auto works A/T vacuum delete
5:1 FD
Airaid intake
Delicious tune
ACE 4-2-1 header and front pipe
RacerX front LCA's (solid bushings)
RacerX rear UCA's
RacerX rear LCA's
TRD door latches
front caynards
Perrrin steering rack bushings
Hardrace stiff motor mounts
Rays 17x8.5 SL's (37et)
20mm spacers rear only
Maxxis RC-1 235/40/17
AP 5200 Sprint kit (ft only)
CL-6 sintered pads (ft and rear)
Essex "harness" bar
51.3% cross weight
45% rear weight
5.6 caster LF (I forget, have to check notes)
5.5 caster RF (I forget, have to check notes)
4* camber LF
2.5* camber RF
4* camber LR
2* camber RR
2mm toe out front
0 toe rear
57cm ride height LF (measured from center of hub to fender with driver (78kg)
57cm ride height RF
57.7cm ride height LR
57.5cm ride height RR
total weight 1218.6kg with driver (2681lbs)

looking to solve T3 (second right after straight ending under bridge)

that's all I can think of right now
thanks

That is an interesting set of changes, left vs. right camber especially.

The video helps alot. From what I see, I think the biggest thing is you need to smooth out your turn in a little more (let the weight transfer onto the outside wheels some instead of hammering). After that I would try slowing down a little more and then accelerating more through the corner (the point being to push the tail of the car out some more). Eventually you can pick back up that speed but only once you are using your rear tires more.

Also, the way you shake your car around is kind of unnecessary. Generally you see racers doing it to scrub the crap off their tires when they come out of the pits, but that doesn't take very much. Trying to get heat in the tires though that sort of means is just asking for trouble.

[Doozer]

Originally Posted by 7thgear

why is your front toe out, and your L/R camber off by so much

Front toe out only because that's how we used to do it in nascar chevy's. guess just old habit. (out is always better then in for the fronts right?)

Right to left camber difference because all high speed turns are right and lefts are generally slower tighter.

Last years link to tire temps and data are here. http://www.ft86club.com/forums/showthread.php?t=80118
We adjust camber by tire temps only. However, the inside LF is always the hottest.

I think we have the only 86 in the world whose rear tires are colder then the fronts...weird...

[Doozer]

Originally Posted by ddeflyer

That is an interesting set of changes, left vs. right camber especially.

The video helps alot. From what I see, I think the biggest thing is you need to smooth out your turn in a little more (let the weight transfer onto the outside wheels some instead of hammering). After that I would try slowing down a little more and then accelerating more through the corner (the point being to push the tail of the car out some more). Eventually you can pick back up that speed but only once you are using your rear tires more.

Also, the way you shake your car around is kind of unnecessary. Generally you see racers doing it to scrub the crap off their tires when they come out of the pits, but that doesn't take very much. Trying to get heat in the tires though that sort of means is just asking for trouble.

Good notes. I've tried different ways of entering 3, but I guess I need to do some data logging to find out which way is actually fastest. Agreed smooth is fast...and it ain't smooth right now

The scrubbing of tires is a bit excessive, I guess it's just getting the butterfly's out. Also, you can't see it, but there's 40+ cars behind me and by weaving it allows me to "hold-up" the field and get 1 or 2 clean laps.

[ddeflyer]

Originally Posted by Doozer

Front toe out only because that's how we used to do it in nascar chevy's. guess just old habit. (out is always better then in for the fronts right?)

Right to left camber difference because all high speed turns are right and lefts are generally slower tighter.

Last years link to tire temps and data are here. http://www.ft86club.com/forums/showthread.php?t=80118
We adjust camber by tire temps only. However, the inside LF is always the hottest.

I think we have the only 86 in the world whose rear tires are colder then the fronts...weird...

Most drivers on street cars (not quite applicable to you, but still) have hotter fronts than rears no matter the car. This is because most cars are setup to understeer (also, most people are scared of really pushing the tail out (myself included)).

[Campo]

Originally Posted by Doozer

Hey folks,



Experiencing understeer on entry in long sweepers and can't break the rear free throughout the rest or the corner. Really, really frustrating.



*snip*



Thanks in advance

I don't have anything constructive to add that others haven't already said before me.

I'm just happy to see another automagic on the track.



Except I don't think anyone mentioned the wheel spacers in the rear. I might remove them since it's the simplest possibility.


Tapatalk - because smoke signals would be too easy.

[swarb]

How should I adjust my single adjustable coilovers? I know they adjust rebound, but dampening is slightly affected. I see people adjust them as if they are dampening adjustable only. But when I read info on double adjustables, the rebound adjustment effect is almost the opposite of dampening.
For example, I am getting a little understeer during off throttle turn in and a little more front roll than I would like. Should I stiffen the front or rear rebound? or soften?

[brn12345]

Originally Posted by Doozer

Good god, long list. Here goes:


that's all I can think of right now
thanks

Ok here are my comments take them for what they are worth:


1. Change to 0 toe front and rear
2. Change to same camber left and right (Suggest -2.5 to -3.0 front and -2.0 rear).
3. Your front end is not planted. Try harder front suspension clicker and softer rear (go full hard then back off 3 for front and 5 for rear), you need to combine this with going back to stock rear sway bar.
4. I don't see sway bar endlinks on your list. If you have them make sure they are adjusted properly, if not get some adjustable ones.


The following you wont like to hear:


1. Ohlin DFV's are not really good road race coil overs. You really need TFX Ohlins or KW Clubsport or equivalent at this level.
2. Get rid of the Maxxis... R7's or V710's are what you should use (32-34 hot pressure).

[celica73]

Doozer - What have you actually tried to do to loosen turn in. Is it just this turn, or all turns? You can't make a car totally balanced everywhere via setup, just not possible. Once it's good in the places that offer the most gains, it is up to the driver.

Having a hard time figuring out what turn, can you give a time point in the video? Is there braking before the turn? Will trail braking initiate some rotation for you? If there isn't any hard braking, will a touch left foot braking get you that rotation?

Run more air in the LR tire.
Adjust the front shocks a click or two softer (or the rear one or two clicks harder).
Run less camber in the LF (this should help turn in, at the expense of everywhere else in the turn)

Hard to tell from the video, but honestly, it looked like the car was tight everywhere. That's great if you want to drive it home, less great for lap records. It seemed like in many of the slow turns it took a long time for you to get back in the throttle, that's a sign of a tight car.

[7thgear]

Originally Posted by travisb

My question is about launches at the start of an autocross. How much wheel spin is desired to get the fastest launch?

Originally Posted by juliog

^ Not much info on this forum

http://www.ft86club.com/forums/showt...ghlight=launch

[Doozer]

Originally Posted by celica73

Doozer - What have you actually tried to do to loosen turn in. Is it just this turn, or all turns? You can't make a car totally balanced everywhere via setup, just not possible. Once it's good in the places that offer the most gains, it is up to the driver.

Having a hard time figuring out what turn, can you give a time point in the video? Is there braking before the turn? Will trail braking initiate some rotation for you? If there isn't any hard braking, will a touch left foot braking get you that rotation?

Run more air in the LR tire.
Adjust the front shocks a click or two softer (or the rear one or two clicks harder).
Run less camber in the LF (this should help turn in, at the expense of everywhere else in the turn)

Hard to tell from the video, but honestly, it looked like the car was tight everywhere. That's great if you want to drive it home, less great for lap records. It seemed like in many of the slow turns it took a long time for you to get back in the throttle, that's a sign of a tight car.

We keep softening the front and stiffening the rear to get it looser. Yes, the car is tight just about everywhere, but like you said, we have to make sure it can still drive home.

Because NA, I've tried trail braking but the car just doesn't have the power and starts to bog down.

I understand fast in one corner means a loss at others, but T3 (3min mark) is a big time loss for me. I think I give up about .5s to the S2000's there. The other .5 is the straight. Nothing I can do about that

Thanks for the input and I'll post feedback after our practice next week.

Take care