Best known practice to correct front geometry?

Discussion in 'Suspension and Chassis' started by Badger, Jun 2, 2019.

  1. rwleonard

    rwleonard TMO Intermediate

    Messages:
    23
    Likes Received:
    17
    Joined:
    Jul 2, 2018
    Location:
    Virginia
    MM has extensive info on their website and is a worthwhile read. One of the things they tout is improved geometry.
     
    Badger and ArizonaBOSS like this.
  2. ArizonaBOSS

    ArizonaBOSS Because racecar. Moderator

    Messages:
    8,189
    Likes Received:
    1,811
    Joined:
    Dec 6, 2010
    Location:
    Arizona, USA
    All of them (including the Ford Performance rack) are the same mechanically. It's all in the programming. Unfortunately, we have been down this road and there is no way to reprogram the racks.
    What I do know is I have an MY2012 BOSS 302 street car rack, built in June 2011, and do not have ANY issues with this. Also it seems that only MY2011 cars are affected by the steering shake. So you may very well be able to get away with a junkyard/used rack from a 12+ S197.
     
    Grant 302 and Badger like this.
  3. Badger

    Badger TMO Intermediate

    Messages:
    71
    Likes Received:
    129
    Joined:
    Dec 15, 2017
    Location:
    SFV
    @rwleonard
    In regards of the MM K-member I am skeptical about marketing speak. E.g. the watts links was so praised as the silver bullet for everything but all I really needed was a cheap v6 sway bar to fix my issues. Nothing wrong the the Watts, it´s a great piece in itself. The real question is, is the K-Member bang for the buck or is the money better invested in other places?

    @Norm Peterson
    My current tires would require -5° of camber due to the mcpherson struts. Yikes. I`m kind of locked in with my current wheels though.

    @ArizonaBOSS I`m more curious about what the benefits between the racing and the stock 12-14 racks are. Or if the difference is neglect-able.
     
    Grant 302 likes this.
  4. blacksheep-1

    blacksheep-1 TMO Addict

    Messages:
    1,722
    Likes Received:
    933
    Joined:
    Mar 12, 2013
    Hole saw for the strut tower......
     
    Badger likes this.
  5. Badger

    Badger TMO Intermediate

    Messages:
    71
    Likes Received:
    129
    Joined:
    Dec 15, 2017
    Location:
    SFV
    Have mercy! I still got 1/2" left on one camper plate and have not used any camber bolts yet either. Are you guys ever going beyond 5?
     
  6. blacksheep-1

    blacksheep-1 TMO Addict

    Messages:
    1,722
    Likes Received:
    933
    Joined:
    Mar 12, 2013
    It depends on the application..

    [​IMG]
     
    byronj, Grant 302 and ArizonaBOSS like this.
  7. neema

    neema TMO Race

    Messages:
    419
    Likes Received:
    89
    Joined:
    Jun 10, 2012
    Location:
    Fresno, CA
    Like some mentioned, geometry. The main thing is the slightly higher A arm pickup, raising roll center and helping the camber curve.

    When you say your 3.7° camber is not enough, are you still seeing more outer tire wear? We're on opposite ends of the spectrum.
     
  8. Norm Peterson

    Norm Peterson Corner Barstool Sitter

    Messages:
    326
    Likes Received:
    268
    Joined:
    Oct 22, 2017
    Location:
    a few miles east of Philly
    Best I could find, but too dark to see the lateral distortion down at the bottom clearly. The wheel itself looks like it's got plenty of negative camber, though.

    [​IMG]

    I'm guessing that being locked into 11's is either a consequence of some competition rule directly or indirectly by your choice on how to use preparation/modification points?


    Norm
     
  9. Badger

    Badger TMO Intermediate

    Messages:
    71
    Likes Received:
    129
    Joined:
    Dec 15, 2017
    Location:
    SFV
    Norm, gotcha. I know what you mean. It´s mostly that I already got my sets of wheels and have other problems to fix first. 18x12 is a pretty penny to dish out.
    Here is a better image:
    tires.jpg

    I ran -3.5 on street tires for a year, which was a pretty good spot and I had pretty even wear on 295 RS4.
    I ran some 275 RSRR for a bit and they kept wearing hard on the outside with -3.5°

    This season though I`m running take off slicks and slicks just need a lot more camber. Everyone who runs slick straight up tells me to go to -5°. Track depended obviously.

    Our front suspension is camber hungry! Fore reference 949 Racing was dialing in their tires of their GT350 based on pyrometer readings at WSIR. They went full -5° on street tires to give the car what it needed.
     
    Grant 302 likes this.
  10. Grant 302

    Grant 302 OPM Spent: $665,833 Moderator

    Messages:
    6,790
    Likes Received:
    1,718
    Joined:
    Nov 23, 2011
    Location:
    In the OC
    Required camber settings vary wildly depending on tires and the rest of the suspension geometry and spring rates and driver skill/style. On top of that, course specific settings like at Streets really matter.

    For myself, when I was on P springs and street tires, I couldn't get enough camber with plates and bolts at Streets. Just after switching to the CorteX/JRi and 305 slicks I had to dial back even a moderate ~2.7º to ~2.4º at Laguna Seca (I remember Ron/moto had to do about the same after our first session). Racked the plates back to max in for Streets on slicks. Back to low 2.xºs on street tires at Chuckwalla.

    People also manage their tire pressures differently. lower hot pressures often need more camber. And there's rim/tire size fitment differences as discussed earlier.

    Anyway, I don't think anyone should be too hung up on what others are running for camber unless you are running the same, same, same. I don't see the 'need' for more camber in those two pics above, but I'm sure it needs more rounding the skidpad.
     
    Norm Peterson and Badger like this.
  11. blacksheep-1

    blacksheep-1 TMO Addict

    Messages:
    1,722
    Likes Received:
    933
    Joined:
    Mar 12, 2013
    a tale of 2 pics....
    your car on a relatively flat turn..
    [​IMG]

    a T2 car on a bank at Homestead/Miami

    [​IMG]

    now the bottom car is limited to about 3 degrees of camber, I want to say that's a 275 tire on a 10 in wheel, but notice the similarity in how far the wheel is punching out of the bead area of the tire, not sure if your car is trying to understeer or not, but you might want to throw a couple of extra psi of air into that tire. Generally..and by that I mean very generally, front engine cars like about 1 to 5 psi more air in the front than the rear. I'm not worried (well, at least at this moment) of the red car losing the bead because of the design of that particular wheel, you, on the other hand, might need to keep an eye on that, especially if it's a painted wheel.
    I've said this before, you guys aren't trying to reinvent the wheel, you're basically building a T2 r T3 suspension, so find one that works, and copy it.
     
  12. Badger

    Badger TMO Intermediate

    Messages:
    71
    Likes Received:
    129
    Joined:
    Dec 15, 2017
    Location:
    SFV
    My car rarely under steers in that turn. The goal is rather to rotate it.
    It`s a fast straight with heavy uphill braking which leads into a slow 180° and slightly cambered turn. Its basically the crest before the track leads downhill again. I´m hitting ~1.2 - 1.3G in that pic. I usually hit 1.4 with a peak of 1.6.

    I´ll try adding some more PSI. The tire is indeed very soft even after the first lap. Depending on the track I usually start at 25-27PSI and end up with 32-33. I do not know the actual temperatures of my tire surface though. I also don´t know what session or lap that picture was taken in.

    S197 are kinda rare on the tracks over here. Only NASA has a hand full of them and I don´t run NASA right now. It`s tricky to find and copy a good example, that`s why I keep asking all these questions.
     
    Grant 302 likes this.
  13. Grant 302

    Grant 302 OPM Spent: $665,833 Moderator

    Messages:
    6,790
    Likes Received:
    1,718
    Joined:
    Nov 23, 2011
    Location:
    In the OC
    Agreed with Badger about this part. Not gonna have access to such cars out here. Even if they were here in SoCal, I'm not gonna expect somebody to share the specifics.
     
  14. blacksheep-1

    blacksheep-1 TMO Addict

    Messages:
    1,722
    Likes Received:
    933
    Joined:
    Mar 12, 2013
    I've tried to share all I know
     
    Badger, Grant 302 and rwleonard like this.
  15. Grant 302

    Grant 302 OPM Spent: $665,833 Moderator

    Messages:
    6,790
    Likes Received:
    1,718
    Joined:
    Nov 23, 2011
    Location:
    In the OC
    Understood and I appreciate that. People in the know are usually very tight-lipped about anything they or their team does. Even more so for winning teams.
     
    Badger and blacksheep-1 like this.
  16. blacksheep-1

    blacksheep-1 TMO Addict

    Messages:
    1,722
    Likes Received:
    933
    Joined:
    Mar 12, 2013
    Don't get me wrong, some stuff is proprietary, but the guys at Phoenix have handed people creepers and let them go under the car. I remember putting the car on the hauler and these guys were looking at it, they were amazed that there was nothing "trick" there..it's mostly in the details...
    my biggest issue is I try to lead someone in a certain direction and they go off and ask everyone else for advice...Okay...you're on your own.
     
    Badger, ArizonaBOSS and Grant 302 like this.
  17. neema

    neema TMO Race

    Messages:
    419
    Likes Received:
    89
    Joined:
    Jun 10, 2012
    Location:
    Fresno, CA
  18. Badger

    Badger TMO Intermediate

    Messages:
    71
    Likes Received:
    129
    Joined:
    Dec 15, 2017
    Location:
    SFV
    I always hold Robs advice in the highest regard and as my baseline. I had a lot of questions recently with a certain amount of overlap. I hope I did not create the perception of inquiring multiple times on the same topic. That certainly was not the intent.

    My buddy and me have the fastest local s197. Which really doesn’t mean anything as no one tracks them and they are kinda rare here. But it also makes it incredibly hard to chase down info in person. You guys though have been really informative and probably helped us a lot more than you are aware :)
     
    Last edited: Jun 12, 2019 at 12:37 AM
    blacksheep-1 and ArizonaBOSS like this.
  19. blacksheep-1

    blacksheep-1 TMO Addict

    Messages:
    1,722
    Likes Received:
    933
    Joined:
    Mar 12, 2013
    You're fine, you gotta go a lot longer ways than that to yank my chain.
     
  20. dabossinnne

    dabossinnne TMO Addict

    Messages:
    548
    Likes Received:
    85
    Joined:
    Aug 6, 2012
    Location:
    Omaha, NE
    If anybody knows how to properly set up an S197 race car it's Rob aka Blacksheep-1, the Aquilantes and Phoenix Racing . Numerous PWC and SCCA class wins including two back to back PWC championships says it all.
     
    Last edited: Jun 14, 2019 at 8:08 PM
    ArizonaBOSS likes this.

Share This Page