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Old 08-23-2017, 08:03 AM   #1826
Xian_1
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Quote:
Originally Posted by speedyHAM View Post
It is a 1 way Cusco set at 60% lockup. What I didn't like is that once power was applied the front end would understeer- always. My car is pretty well optimized and prior to the last set of suspension subframes it would go up on two wheels on certain high grip surfaces. After I fixed that the front end would wash out far sooner than the rear when on power out of corners.

Rear diff was (and is) a Cusco clutch set at 100% lockup. Type MZ I think, the one that will lock up at 1 mph vs. the street driveable one. Most people think my car is broken when I pull out of a parking lot space.
It's been quite a while since I did much reading on roll centers but, if you were bicycling the car, my first reaction would be that there's a bigger problem than the diff causing an on throttle push. Just seems odd to me that you're the only person who's seen a clutch diff create an understeer situation on throttle and you also were lifting inside tires. :shrug:

Maybe Tim or someone with additional experience will chime in.
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Old 08-23-2017, 01:17 PM   #1827
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Originally Posted by Xian_1 View Post
It's been quite a while since I did much reading on roll centers but, if you were bicycling the car, my first reaction would be that there's a bigger problem than the diff causing an on throttle push. Just seems odd to me that you're the only person who's seen a clutch diff create an understeer situation on throttle and you also were lifting inside tires. :shrug:

Maybe Tim or someone with additional experience will chime in.
SpeedyHAM, you're talking about an XP car not an SM car right? I'm guessing your car is a lot more tuned up than the SM cars this thread is discussing. You might be fighting a set of issues that the rest of us haven't even encountered yet.
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Old 08-23-2017, 02:37 PM   #1828
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Quote:
Originally Posted by speedyHAM View Post
It is a 1 way Cusco set at 60% lockup. What I didn't like is that once power was applied the front end would understeer- always. My car is pretty well optimized and prior to the last set of suspension subframes it would go up on two wheels on certain high grip surfaces. After I fixed that the front end would wash out far sooner than the rear when on power out of corners.

Rear diff was (and is) a Cusco clutch set at 100% lockup. Type MZ I think, the one that will lock up at 1 mph vs. the street driveable one. Most people think my car is broken when I pull out of a parking lot space.
The RS when setup at 100% is basically the same as the MZ. I had the RS for 3-4 years and can tell you it's the rear diff combined with keeping the rear wheels on the ground that is causing the issue. You have to set the car up to hike it's rear inside tire, then it'll turn.

Quote:
Originally Posted by Xian_1 View Post
It's been quite a while since I did much reading on roll centers but, if you were bicycling the car, my first reaction would be that there's a bigger problem than the diff causing an on throttle push. Just seems odd to me that you're the only person who's seen a clutch diff create an understeer situation on throttle and you also were lifting inside tires. :shrug:

Maybe Tim or someone with additional experience will chime in.
Bicycling some is ok. Doing it all the time is bad. Too many people focus too much on keeping wheels down IMO. Even with a bunch of geometry correction my car still lifts wheels (although almost never a front). Still, like I said above, it's not the front diff that's causing this, it's the rear diff.

Quote:
Originally Posted by Suba_Roo View Post
SpeedyHAM, you're talking about an XP car not an SM car right? I'm guessing your car is a lot more tuned up than the SM cars this thread is discussing. You might be fighting a set of issues that the rest of us haven't even encountered yet.
XP isn't really that far beyond SM. They weigh less, but you can fix the geometry pretty much as well in SM as in XP. it's just harder in SM. I've fixed the issues he's having on my car
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Old 09-07-2017, 06:24 PM   #1829
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Not sure if people are following. subydude is doing pretty well at nationals

http://sololive.scca.com/SM.php
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Old 09-08-2017, 06:38 PM   #1830
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Not sure if people are following. subydude is doing pretty well at nationals

http://sololive.scca.com/SM.php
Must be the connecting rods

I was thinking about those rods this morning as I woke up (yeah, I know, I'm broken). ~130 grams per rod lighter than OEM STi rods. So about 1.14 lbs of reciprocating mass out of the bottom end. Shoot, I should upgrade you to some lighter wrist pins now too, now that I've got some more limit pushing under the belt. Pair that with a billet crank (about 2-3 lbs) off of rotating mass....that bottom end would have a FIELD DAY with a sequential trans.
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Old 09-12-2017, 03:21 PM   #1831
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Must be the connecting rods

I was thinking about those rods this morning as I woke up (yeah, I know, I'm broken). ~130 grams per rod lighter than OEM STi rods. So about 1.14 lbs of reciprocating mass out of the bottom end. Shoot, I should upgrade you to some lighter wrist pins now too, now that I've got some more limit pushing under the belt. Pair that with a billet crank (about 2-3 lbs) off of rotating mass....that bottom end would have a FIELD DAY with a sequential trans.
I mean, if you want to make another set I'm starting to build a spare block.....just saying I'd be happy to talk to you about other internals if you've got other ideas too

Sequential trans is baller, but I don't have baller money. Speaking of transmissions, I broke the unbreakable and sheared the teeth off 1st and 2nd at the Pro Solo on Saturday so now I'm hunting a gear stack. I had another 6-speed there without the good gearing that I was going to sell to someone that ended up going in my car for Nats. Sadly, the lack of good gearing and some shock/power steering issues landed me in 5th over all out of 25 in class and 92nd in pax out of 1,300+. I was on the podium day 2 until final runs too so that was a mildly rough 5 minutes when the second drivers finished their runs

Glad people had fun following along. I always encourage people to come out even if they don't think they're ready. It's a riot of a week and seeing all the cars out there is always amazing.

Congrats to Dan on the 2nd place position (on stock rods too)! The AWD cars are coming closer and closer to the top spot again.
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Old 09-15-2017, 07:13 PM   #1832
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I need to get out there 1 of these years
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Old 09-15-2017, 10:45 PM   #1833
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I need to get out there 1 of these years
Its a blast being in the SM grid, even when trophies are out of reach. So much awesome machinery and cool people. I'll be there again in '18 hopefully. I should think about adding more power. lol.
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Old 09-16-2017, 11:49 AM   #1834
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Come for the cars, stay for the Trasharita!
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Old 09-21-2017, 10:26 PM   #1835
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Brainstorming on engine for next year. After 4 years it's time to rebuild mine and I'm debating between 2.35 and 2.5.

Option 1 = 2.5 + 07+ gearing. Pretty standard setup.

Option 2 = 2.35 with 04-06 gearing and ~9k redline. 2nd gear is about 6% shorter than 07. If you can rev 6%+ faster than the 2.5, you have an advantage on top speed before shifting. Then you get 6% more wheel torque, so even if the engine produces a bit less torque, still end up similar acceleration. Engine spool later in RPM, but you get 6% advantage in actual speed at which the turbo will spool. You can remove 50-60 lbs from the car. Bonus you get to use all your cluster RPM range and less chances to break drivetrain

Thoughts?
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Old 09-22-2017, 10:06 AM   #1836
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I'm working on a group buy for a regear to 3.54 final drive. Do the 2.5 and either trans with that and you don't have to worry about revving high. PM me if you're interested.
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Old 09-23-2017, 10:58 PM   #1837
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taller final drives only put more stress on the trans....
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Old 09-25-2017, 09:44 AM   #1838
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Originally Posted by Homemade WRX View Post
taller final drives only put more stress on the trans....
While true, it's not a huge jump for 1st gear. I'm pretty sure my case was something special since I was launching it a LOT on 335's. DR would actually be easier on the gears I think.
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Old 09-29-2017, 12:59 AM   #1839
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XP isn't really that far beyond SM. They weigh less, but you can fix the geometry pretty much as well in SM as in XP. it's just harder in SM. I've fixed the issues he's having on my car
You need to look more at the XP rules. I have custom front and rear subframes with relocated suspension pickups along with different length control arms. I have also modified the locations of a few of a chassis pick up points. My weight (last time I ran) was 2012 lbs after my 3rd run, so the weight difference is a lot.

I played with the lockup of the front diff a few times and never got it to work the way I wanted.

I was pretty much always lifting a rear tire on corner entry, then I would switch occasionally to lifting a front tire on corner exit.

Hope to see you all at Nats in 2018.
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Old 09-29-2017, 10:55 AM   #1840
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Originally Posted by speedyHAM View Post
You need to look more at the XP rules. I have custom front and rear subframes with relocated suspension pickups along with different length control arms. I have also modified the locations of a few of a chassis pick up points. My weight (last time I ran) was 2012 lbs after my 3rd run, so the weight difference is a lot.

I played with the lockup of the front diff a few times and never got it to work the way I wanted.

I was pretty much always lifting a rear tire on corner entry, then I would switch occasionally to lifting a front tire on corner exit.

Hope to see you all at Nats in 2018.
I should have been more clear. I know XP is a good bit beyond SM overall, but my geometry is likely almost as good as yours now. We can't touch the inbound points, but everything else (arms, uprights, etc) is open.

Should be fun in 2018!
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Old 10-26-2017, 01:07 PM   #1841
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So friends, new FastTrack proposes unlimited and open motor swaps.

What v6 is short enough to fit in our bay and retain the 6 speed?
- letís ignore the inherent height complication and placement of steering rack for now.

Discuss.
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Old 10-26-2017, 02:46 PM   #1842
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Why V6?
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Old 10-26-2017, 02:56 PM   #1843
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LS all the things!
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Old 10-26-2017, 03:03 PM   #1844
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Doesn't that class already exist?

Good luck fitting something else (big) with our stock subframe.
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Old 10-26-2017, 05:58 PM   #1845
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Subframes are open assuming stock weight or more and stock geometry is retained. Have been for a few years.

The weight calculations are based on displacement so going up to LS levels of displacement means adding a TON of weight.

I don't see anyone really changing right now.
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Old 10-26-2017, 06:17 PM   #1846
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Obviously the 911 turbo motor sounds interesting. 540 HP stock. Some tuning and e85... Our Subys can break drivelines even more efficiently.
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Old 10-26-2017, 06:36 PM   #1847
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M97/74 please.
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Old 10-26-2017, 06:46 PM   #1848
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Quote:
Originally Posted by Krang View Post
So friends, new FastTrack proposes unlimited and open motor swaps.

What v6 is short enough to fit in our bay and retain the 6 speed?
- letís ignore the inherent height complication and placement of steering rack for now.

Discuss.
Joking about fun motor swaps aside, I hope this doesn't get approved. Next step is a transmission from any manufacturer and at that point for a Suby chassis to be competitive at all, we will need to swap in something like a Ford Focus RS driveline thereby moving the engine mass way back behind the front axle.
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Old 10-26-2017, 10:25 PM   #1849
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Meh, EG33 up front with a GTR rear transaxle. Clint at TIC and I had talked about this 5 years ago when they were still running their TA car.

Andy Forrest now has that very combo in his WTAC car.
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Old 10-26-2017, 10:33 PM   #1850
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Transmissions are already open. You could run a 2 speed power glide if you wanted.
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