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Old 09-24-2019, 01:15 PM   #3739
M0nk3y
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I'm getting a little frustrated with my setup development so maybe the community here has some helpful advice. Throughout the last two years of running a twin in STX I have tried a variety of setups in terms of spring rates and sway bars and I have consistently had issues with mid-turn push. The current setup is 350F/400R, stock rear bar, Karcepts front bar. Caster is 7*, 4.1* camber in the front and 2.5* in the rear. I have about 3mm of positive rake. I currently run rivals and I run the fronts at 27 PSI and I get just a little roll over on the edge but not a lot. I've tried down to 26 PSI and that was definitely not an improvement. I've checked tire temperatures and I find about 15* warmer on the inside edge with the middle measuring closer to the outside edge than the inside which has led me to experiment again with higher front pressures which has yielded mixed results. I like the turn in but it doesn't help my mid turn grip problem. Turn in feels very good as is and the car transitions pretty well. Once I shed enough speed to get the front end planted the car exits very well with good balance on throttle. Generally adding throttle to rotate out of the push will just cause more push unless the speed is just right to have the power to really break the rears loose. The car also will not trail brake at all. Holding a little brake in to a turn just causes the car to push on entry rather than turn in nicely before pushing. Almost every single sweeper or 90* at nats was a nightmare. I was slowing more than I wanted to before turn in, getting a decent entry and then once the car was set the front end just pushed until I shed enough speed to be able to get on the gas so I was always on the gas late.

I've ended up adjusting the front bar down to the third softest setting of 7 which is still rather stiff at 346 lbs. In order to keep turn in crisp when changing to softer sway bar settings I have bumped front compression damping up to about 7 clicks on MCS.

The obvious course of action I think would be to continue softening the front or to stiffen the rear but the problem I am running in to is that the front is already getting to the point where it's soft enough to be close to running out of travel. I made sure that I'm maximizing travel in the front when installing this suspension system. I use a bump stop that contacts the damper body within a few mm of when the tire contacts the fender liner. I am not currently running out of front travel but pictures of the car on course show that it's not too far from doing so. I've tried the front bar all the way up to almost full stiff and that really made the problem worse. I've tried a stiffer rear bar but that made the rear end really snappy under throttle and I had trouble putting power down. I believe the next thing I am going to try is stiffer rear springs (450 lbs as I can't find any 425s in the right length) and if the car gets too loose I can balance that out with more front sway. I'm not really a fan of this solution though because I already am not using all of my rear travel. I took a video of the rear suspension motion at the damper on a rough road through some hard turns and found that the suspension is really only traveling through 60% of the available range and as such stiffer springs will really only act to sacrifice rear grip rather than to improve front grip.

Another solution I have considered is to use some rear toe out. I have usually kept rear toe at 0 but currently I have just a hair of rear toe in, about 2mm total.

Understandably, many will say that this problem is more a result of driving style than of setup. I have been trying to drive around this by reducing entry speeds and keeping steering inputs smooth but in order to avoid this mid-turn push I end up sacrificing entry speed so much that I'm just slow. Not to mention, using some rear compression damping has the car so balanced on initial turn in that it's even harder to give up that entry speed.

I would appreciate any constructive input on this. I'm just stumped as to whether the front end is pushing because it's too stiff, is it a matter of tire pressure and/or camber, is it that there is not enough front roll stiffness and the body is rolling too much, or are the weight distribution and other inherent characteristics of this car just such that I need to accept limiting rear travel and grip by going too stiff on the rear springs in order to get the car balanced out mid turn so I can get on the throttle earlier.
Late reply here so I apologize, too busy licking my wounds from Nats lol

The main things I've picked out is that you seem to run the rates opposite of me. I'm 400/350 which typically use to be the lemming setup until Lugod came on in here and upset the apple cart. I do think his rates work (I mean they obviously did) but with a defined setup which revolves around OSG.

Obviously you're most likely going to disagree when I say swap the rates, but the only reason I'm saying this is because you're trying to add artificial spring with bump on MCS. 7 Clicks of bump is ALOT (at least knowing from my shocks and revalved shocks I don't think about going past 4). I run a decent amount of bar (I was 2/2 on Karwan's bar at Nats) and usually 2/3 everywhere else.

Here's my video from Nats. They aren't pretty, but should show how the car was working for me.

[ame]https://www.youtube.com/watch?v=cRS8m0DB_ck[/ame]

[ame]https://www.youtube.com/watch?v=9Z-E19lmLgc[/ame]

[ame]https://www.youtube.com/watch?v=L3rkavXUz0Y[/ame]
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Old 09-24-2019, 01:26 PM   #3740
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Thanks for the reply. I could try flipping the springs. I have tried rates similar to that in the past (350f/275r iirc) and the car honestly wasn't much different than it is now.

So with your spring rates you don't experience much mid turn push? It looks like around mid turn on some sweepers you add more steering input without a lot of response. It's hard to see what the rear is doing in a video though. Having watched your car on course, it certainly doesn't look pushy from the outside.

Also, are you that low on rear compression as well or do you use more?
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Old 09-24-2019, 01:37 PM   #3741
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Thanks for the reply. I could try flipping the springs. I have tried rates similar to that in the past (350f/275r iirc) and the car honestly wasn't much different than it is now.

So with your spring rates you don't experience much mid turn push? It looks like around mid turn on some sweepers you add more steering input without a lot of response. It's hard to see what the rear is doing in a video though. Having watched your car on course, it certainly doesn't look pushy from the outside.

Also, are you that low on rear compression as well or do you use more?
Forgot to add I'm at 1/8" rake, and considering going to 0 neutral rake next year to keep the rear end planted more. I'm -4.2* front, -2.5* rear and 1/16th total toe in at the rear. I also have caster plates yielding an additional degree of caster - however never measured to see how much caster I'm actually running.

Lincoln is weird, also insert the whole "I'm running Yokohama tires which I've never ran before" clause in there too. I was dealing with push with loose exit Thursday on the West. Decided to go up in front bar and try to tighten up the car on exit that way and drive through push. It wasn't necessarily pushy mid-corner per say, but it wasn't ideal for me. Tried to play around with shocks a tad to get the car to rotate a bit more on entry and ease the tightness on push - I did the best I could. Car was PERFECT for me at the Finale - sucks it became worse during when it actually mattered

I'm same range on rear compression as well, usually within a click of each other front to rear. Rebound up front is usually 9-12 clicks, rear is around 6-12 depending on surface and car behavior. I tend to play with rear rebound the most.

[ame]https://www.youtube.com/watch?v=8yPnTBOYk4s[/ame]

I can link video upon video. But this is how the car was on BFGs at Oscoda
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Old 09-24-2019, 04:27 PM   #3742
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Thanks for the replies. My setup would be pretty much exactly like yours if I swapped the springs. Very close. maybe I'll just give it a try after the next event where I'm just going to play with the sway bar, compression damping, and tire pressures to see what I can do with that. I have a feeling that a large part of the problem might be too much compression damping and not enough front tire pressure.
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Old 10-06-2019, 09:24 PM   #3743
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Update: increasing the front spring rate to 400 and lowering the rear to have no rake made a huge improvement. This is counterintuitive to what I thought I knew about setup but the car sure is much better now.
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Old 10-07-2019, 07:36 AM   #3744
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Flip to 400/350 or just go up in the front to 400/400?
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Old 10-07-2019, 08:00 AM   #3745
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Update: increasing the front spring rate to 400 and lowering the rear to have no rake made a huge improvement. This is counterintuitive to what I thought I knew about setup but the car sure is much better now.
Awesome, good to hear.
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Old 10-07-2019, 03:22 PM   #3746
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Flip to 400/350 or just go up in the front to 400/400?
So far I just upped the fronts so it's 400 square. Just making incremental changes. I believe I have some more tweaking to do before dropping the rears to 350 because while the car did feel much better it was still more pushy than loose. I had the fsb set almost all the way soft. I'm not sure the softer rear springs would work too well for me without a stiffer rear bar. Of course, I previously had a stiffer rear bar but decided I didn't like it and sold it. Maybe karwan will release his rear bar for the twins one of these days.
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Old 10-08-2019, 07:19 PM   #3747
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Is there anyone on this thread who's interested in an OS Giken limited slip with the STX tune and the OS Giken fluid?


It's new in its box - it was only opened to confirm it was tuned for STX tires.


I'm not fully committed to selling yet, but I have too many parts lying around.


PM me if you're interested.
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Old 10-30-2019, 11:57 AM   #3748
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I'm sure this has been answered somewhere in this long thread. But are aftermarket front splitters and rear diffusers and other areo parts legal in STX or were that bump you into SM?
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Old 10-30-2019, 02:17 PM   #3749
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Factory option aero only. And there is even some factory option aero that is not allowed (860 edition spoiler).
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Old 11-06-2019, 02:21 AM   #3750
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Hey all, I am going to try to take autocross seriously this next season and have a few questions on my car and what class it falls in.

After perusing the thread I think my car no longer would fall in DS or STX based on the 2019 rules

Mods are as follows
- Racecomp yellow springs
- stock shocks
- OFT E85 tune
- TRD short throw shifter kit
- perrin shifter mount bushing
- perrin CAI (I have the stock to put back in if necassary)
- catback (technically has mufflers but they are blown out)
- Gmax A/S 05 tires 225/45/R17, though I will probably get some good summers for Autox
- Strut tower brace
everything else is stock.

So after reading this thread and the 2019 rules I believe the car would be in C street Prepared, would I be correct in that assumption?

that being said, would I be better off trying to get the car back to STX?

Also, if I stay in street prepared, I know I can do some additional modifications, SS brake lines, any other things to suggest?

ok, and lastly, I know street prepared allows for removal of stock engine fan, stereo, and speakers, is there any other 'free' mods that I can do that can be restored back to a more street friendly configuration after the race relatively easily?

EDIT: my front grill likes to come loose, can i remove it?

Thanks for any and all help!
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Last edited by Takumidesh; 11-06-2019 at 02:24 AM. Reason: added question
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Old 11-06-2019, 08:29 AM   #3751
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Quote:
Originally Posted by Takumidesh View Post
Hey all, I am going to try to take autocross seriously this next season and have a few questions on my car and what class it falls in.

After perusing the thread I think my car no longer would fall in DS or STX based on the 2019 rules

Mods are as follows
- Racecomp yellow springs
- stock shocks
- OFT E85 tune
- TRD short throw shifter kit
- perrin shifter mount bushing
- perrin CAI (I have the stock to put back in if necassary)
- catback (technically has mufflers but they are blown out)
- Gmax A/S 05 tires 225/45/R17, though I will probably get some good summers for Autox
- Strut tower brace
everything else is stock.

So after reading this thread and the 2019 rules I believe the car would be in C street Prepared, would I be correct in that assumption?

that being said, would I be better off trying to get the car back to STX?

Also, if I stay in street prepared, I know I can do some additional modifications, SS brake lines, any other things to suggest?

ok, and lastly, I know street prepared allows for removal of stock engine fan, stereo, and speakers, is there any other 'free' mods that I can do that can be restored back to a more street friendly configuration after the race relatively easily?

EDIT: my front grill likes to come loose, can i remove it?

Thanks for any and all help!
With the E85 Tune you're in CSP. Remove the E85 and run off of 93 Oct and you'll be in STX with the rest of the mods you have currently configured.

I'd advise staying away from CSP, or Street Prepared in general. They run on DOT Slicks (Hoosiers) and is just massive scope creep from what you have currently.
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Old 11-06-2019, 08:52 AM   #3752
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Quote:
Originally Posted by Takumidesh View Post
Hey all, I am going to try to take autocross seriously this next season and have a few questions on my car and what class it falls in.

After perusing the thread I think my car no longer would fall in DS or STX based on the 2019 rules

Mods are as follows
- Racecomp yellow springs
- stock shocks
- OFT E85 tune
- TRD short throw shifter kit
- perrin shifter mount bushing
- perrin CAI (I have the stock to put back in if necassary)
- catback (technically has mufflers but they are blown out)
- Gmax A/S 05 tires 225/45/R17, though I will probably get some good summers for Autox
- Strut tower brace
everything else is stock.

So after reading this thread and the 2019 rules I believe the car would be in C street Prepared, would I be correct in that assumption?

that being said, would I be better off trying to get the car back to STX?

Also, if I stay in street prepared, I know I can do some additional modifications, SS brake lines, any other things to suggest?

ok, and lastly, I know street prepared allows for removal of stock engine fan, stereo, and speakers, is there any other 'free' mods that I can do that can be restored back to a more street friendly configuration after the race relatively easily?

EDIT: my front grill likes to come loose, can i remove it?

Thanks for any and all help!
I know it is a bit of a drive from Greensboro, but the CCRSCCA events at zMax usually have a pretty large open STX class and will likely have a couple of "pro class" STX twins at events next year.

You'll have a lot of fun comparing to those folks.
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