Setting up the LGT for SCCA Classes (D Street -> STX -> ASP -> SM)

[StoplightAssassin]

The more popular a car is, the more favorably it is classed. Usually, newer cars take precedent in classing.

 

Course dependency can be an issue. Big turbo cars will go slow at small sites, but the small turbo cars might not have much of an issue, especially new turbo cars, where they make max torque from around 2k RPM.

 

If your tires look that bad after 1 event, it's the alignment, the tire compound, or both. A dedicated set of extreme performance summer tires will last longer than most max performance summers. Not sure how the new PS4S and Conti ECS will hold up.

[whitetiger]

anyone here sign up for the NJ Prosolo?

[covertrussian]

The more popular a car is, the more favorably it is classed. Usually, newer cars take precedent in classing.

 

Ain't that the truth. If they keep on putting nice fast cars into H Street (as log as it goes), we are gonna need a Lemon class or something

 

Course dependency can be an issue. Big turbo cars will go slow at small sites, but the small turbo cars might not have much of an issue, especially new turbo cars, where they make max torque from around 2k RPM.

 

Indeed, our courses are usually 60 seconds for fast cars. I used to run a GT2860r (Disco potato), but it was still too slow boosting. Downsized to GT28r which is a slight step above T25 and it's much more autox friendly, but now since boost sets in so early wheel spin occurs much sooner

 

 

If your tires look that bad after 1 event, it's the alignment, the tire compound, or both. A dedicated set of extreme performance summer tires will last longer than most max performance summers. Not sure how the new PS4S and Conti ECS will hold up.

 

Our course is a government parking lot in a small city. Lets just say there is 3 distinct pavement types, and all of them are grit 0. With high power FWD and lots of understeer it just destroys the tires. Last set of tires was AD08's which lasted me a decent amount, current set is copper RS3-S's and 2.5k miles in the drive side is bald. So going back extremes next tire purchase.

[bucko3the7man]

anyone here sign up for the NJ Prosolo?

 

Not me. Trying to finish my Kitchen remodel in some semblance of soon.

 

Ain't that the truth. If they keep on putting nice fast cars into H Street (as log as it goes), we are gonna need a Lemon class or something

 

 

 

Indeed, our courses are usually 60 seconds for fast cars. I used to run a GT2860r (Disco potato), but it was still too slow boosting. Downsized to GT28r which is a slight step above T25 and it's much more autox friendly, but now since boost sets in so early wheel spin occurs much sooner

 

 

 

 

Our course is a government parking lot in a small city. Lets just say there is 3 distinct pavement types, and all of them are grit 0. With high power FWD and lots of understeer it just destroys the tires. Last set of tires was AD08's which lasted me a decent amount, current set is copper RS3-S's and 2.5k miles in the drive side is bald. So going back extremes next tire purchase.

 

Lemon class - There's always STS I guess? But you're just going to be beaten by CRXs and Miatas there anyways. G20 has no good class really.

 

Bald driver side tire - this sounds like a case of Open Diff FTL or too much skinny pedal while understeering. I'd recommend fixing your understeer issue with a rear bar or something if you're looking to stay in HS. If you're talking the SMF car then you can do pretty much whatever you want to fix this.

[covertrussian]

Lemon class - There's always STS I guess? But you're just going to be beaten by CRXs and Miatas there anyways. G20 has no good class really.

 

Bald driver side tire - this sounds like a case of Open Diff FTL or too much skinny pedal while understeering. I'd recommend fixing your understeer issue with a rear bar or something if you're looking to stay in HS. If you're talking the SMF car then you can do pretty much whatever you want to fix this.

 

Ha I'm already in SMF, car has an NA SR20 stock, it's hard not to slap a turbo on it . Car is making about 230whp/wtq currently, fairly quick in straight line and handles decent in long turns but short technical corners is where she suffers.

 

I got a helical LSD (stock part of the Spec V trans actually). I've been fighting with fixing the understeer ever since I started racing the car (which was a month after I bought the car ). Nissan was so afraid of oversteer that they engineered a lot of terminal understeer into it. The car refuses to rotate, I didn't know how bad it was until I bought the 4th gen LGT.

 

Here is what my setup was up until last week, which still was very understeer prone:

• Fortune Auto 500 Coilovers 8k front springs, 10k rear springs
  
• Addco rear swaybar solid 22mm
  
• -1.5* rear camber stock (not adjustable without bending the beam)
  
• -0.5* front camber (from lowering 1", not adjustable without new arms or elongated bushigns. New arms are usually 10mm shorter = only -1* gain). I gain about -0.6* per inch of travel. I just picked up some SuperPro UCA bushings for -1* of camber static gain.
  
• 10mm ALK kit
  
• Super pro caster bushings (~3.5* total)
  
• 225/45/17 on 17x7.5" +40mm wheel with rolled fenders, not much room for bigger. Might be able to do 235 with +30 wheels (but 4x114.3 has very limited wheel options).
  
• Front roll center is at or below the ground
  
• Rear roll center is at around 12"
  
• Tire Pressures during racing: 36f/42r
  
• Front toe 0"
  
• Rear toe 0-1/16" (had to bend the beam, stock was 1/8")
  

 

Full build thread can be found here.

 

Last weekend I put 5k front SWIFT springs (had them laying around the garage). This made the rear 5k lbs stiffer, I then used the following tire pressures 32f/38r and the car was finally rotating in some turns but still overloading the front tires like crazy.

 

I'm now in progress of building a new panhard bar (which is allowed even in lower classes) that will lower the rear roll center to be about 6-7". From what I'm told this is the main reason these dead axle cars roll over front wheels so much. I'll post my build pics in the car build page on this site once I'm done welding.

[bucko3the7man]

I think you're on the right track increasing the difference. I would step the rear up even more still keeping the 5k springs in the front. 14k should be closer to good, and should still allow the front to droop enough. Do you have any autocross videos to show us?

[StoplightAssassin]

Without knowing anything about G20s, I look at that alignment and think that car is going to understeer quite a bit. Is it MacPherson strut in the front?

[StoplightAssassin]

anyone here sign up for the NJ Prosolo?

 

No. Car is not ready. BiL is dicking around so I can't get my new exhaust fabbed up. Then I desperately need a corner balance.

[covertrussian]

Sorry for the thread jack, I was just ranting about SCCA classing being biased against uncommon cars. You guys feel free to carry on the discussion at the build thread, or maybe mods can move the post there. Here are some pics of it autocrossing when it was still fairly stock.

 

I think you're on the right track increasing the difference. I would step the rear up even more still keeping the 5k springs in the front. 14k should be closer to good, and should still allow the front to droop enough. Do you have any autocross videos to show us?

 

I gotta get my gopro running again, my battery decided to bloat. Last videos I had were on stock suspension or weak drop in springs so wouldn't even be the same.

 

14k seems pretty intense, I'm hoping autocross pics get posted from last weekend, if I'm already dog peeing (3 wheeling) increasing spring rates wont matter.

 

Without knowing anything about G20s, I look at that alignment and think that car is going to understeer quite a bit. Is it MacPherson strut in the front?

 

It's actually a multi-link, it's supposed to gain camber on roll, but the camber curve is abysmal on it. Stock is 0*, 1" compression it only gaines about -0.35*. I've considered just doing a mcpherson strut conversion from Sentra's. That at least would let me run -2* camber static and maybe more caster

[StoplightAssassin]

It's actually a multi-link, it's supposed to gain camber on roll, but the camber curve is abysmal on it. Stock is 0*, 1" compression it only gaines about -0.35*. I've considered just doing a mcpherson strut conversion from Sentra's. That at least would let me run -2* camber static and maybe more caster

 

That's tough, but it wouldn't be so bad if not for all the camber in the rear.

 

What's the rear suspension setup? Run 1/16th toe out?

[covertrussian]

That's tough, but it wouldn't be so bad if not for all the camber in the rear.

 

What's the rear suspension setup? Run 1/16th toe out?

 

Ha I wish it was 1/16th toe out. Beamed Nissan's ship with 1/4" to 1/8" toe in rear beams. This car had 1/8", I bent it out to 0 toe, but mechanical bending seems to spring it back overtime. I have a warped rotor with too much run out, so I'm seeing around 1/16" toe in right now.

 

I've been thinking about the camber myself, maybe I should try to bend the beam out to have only -1.0* camber...

 

Do you have any autocross videos to show us?

 

It's no video but here is a pic of the car rolling on drop in springs. I just posted a bunch more pics here.

http://i160.photobucket.com/albums/t188/covertrussian/Cars/00%20G20t%20KH3/Pics/Racing/AutoX/20120812_003.jpg~original

[Dujo]

No worries about a threadjack. We've been talking about Miata setups in here too. Let's just call this the current autocross thread for LGT.com members that care to post and follow and all discussion is welcome. Try to keep the sammichs to a minimum. Enjoy!

[covertrussian]

Here is the the car rolling on with 8k/10k spring rates, strut bars, rear swaybar, and 205/50/15 AD08's.

http://i160.photobucket.com/albums/t188/covertrussian/Cars/00%20G20t%20KH3/Pics/Racing/AutoX/2015-05-31_001.jpg~original

 

Here it is with 225/45/17 RS3-S tires and 10mm shorter UCA's (about -1.3* neg camber).

http://i160.photobucket.com/albums/t188/covertrussian/Cars/00%20G20t%20KH3/Pics/Racing/AutoX/2016-0501_Verona01.jpg~original

 

Just for kicks and giggles here's a pick from 2010 with me being in H Street on 100k mile stock everything. I'm surprised it didn't flip

http://i160.photobucket.com/albums/t188/covertrussian/Cars/00%20G20t%20KH3/Pics/Racing/AutoX/20100815_002.jpg~original

[covertrussian]

To continue on the SCCA classing rant. Last weekend we had a bone stock Taurus show up, well it was so much of a beater that it was missing two interior door panels. He got classed in SMF

[whitetiger]

weight reduction is weight reduction.

[bucko3the7man]

the only mod that can help a car turn, brake and accelerate better!

[whitetiger]

that and tires.

[StoplightAssassin]

and the driver

[Dujo]

I removed the sun visors on the Miata. Can I stay in ES like that? Shaved a good ten or eleven ounces. But since the driver more than makes up for any weight savings there, I'ma call it good.

[bucko3the7man]

Now that I can actually see the Russian's pictures, I think you are using the steering wheel too much. lots of steering input in those pictures, I can see hwo the front would be overwhelmed and just understeer on you.

[covertrussian]

Now that I can actually see the Russian's pictures, I think you are using the steering wheel too much. lots of steering input in those pictures, I can see hwo the front would be overwhelmed and just understeer on you.

 

Thanks for the feedback. Best reason I can come up with is, the car is refusing to turn causing me to overdue on steering.

 

Front outside overloading and terminal understeer is very common issue with beam Nissan's built in late 90's and early 2000's. All cars that use the Scott Russell lateral link suffer from very high rear roll centers. I just measured mine at 11.5" (stationary) from the ground on 225/45/17 tires. Mike Kojima covers it pretty well on his build page of a race car Sentra.

 

 

Scott Russell Linkage (from another car, thanks wikipedia):

 

I just finished welding up my beam for a panhard bar today, made adjustable too, I set it to have a 6" stationary roll center.

http://legacygt.com/forums/attachment.php?attachmentid=247417&stc=1&d=1491715292

 

Since this is a crude and simple panhard bar even classes below SM allowed one to be installed . But what a difference did it make, even without the rear swaybar (wont fit with panhard bar's beam mount). The car rotates much better now with the rear coming out a little too easily. Time to start removing oversteering inducing mods (stiff springs and high rear tire pressures mainly).