Re: Circle Track suspension and steering advice
[Re: MadMez]
#1285773
08/15/12 03:52 PM
08/15/12 03:52 PM
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Joined: Jan 2003
Posts: 5,394 Pikes Peak Country
TC@HP2
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master
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Posts: 5,394
Pikes Peak Country
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Anderson Speedway or Slinger Speedway? I've heard one of them recently stole the fastest 1/4" mile oval title from my track, I25 speedway, in Pueblo Colorado. Our record was a 10.48 from a Super Mod car back in '92. I don't think we've had any of them back there since then.
Biggest problem you will have with running any mopar on a high banked oval is t-bar sizes. The biggest you can stuff under a B body is 1.22, which is 400# wheel rate. This translates to the equivilent of a 800# spring for the chevy boys. When I was running at I25, we were running 1000# RF spring to be competitive. If your track has some serious banking, you will need the big spring rates to avoid bottming out the suspension, or you'll run at the back of the pack. Do you know what the fast cars in that class are running now?
You can sort of compensate some with sway bars sizes, but since you have a rule limiting that, you're in a pinch. Of course you could go out on a limb and run two smaller sway bars stacked on top of each other, but that would likely only get you through one night before they outlaw it.
FJM cars would be a bad choice because of the t-abrs they use. Way too soft. A body may work, but again you have a 3200# minimum weight rule and they can only runa 1.18 t-bar, which is 370#, so your giving up 30# of rate comapred to a B body.
Do you have wheel base limtiations to consider at all because they may dictate whether you can even consider an A body. Most entry level racing classes spec this to try and get larger cars out in those classes.
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Re: Circle Track suspension and steering advice
[Re: TC@HP2]
#1285775
08/15/12 04:44 PM
08/15/12 04:44 PM
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Joined: Dec 2003
Posts: 22,727 Bitopia
jcc
If you can't dazzle em with diamonds..
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If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 22,727
Bitopia
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Seems to me the biggest hurdle is tb size. I run both a and b/e bodies never noticed the hex sizes are different. The rule quoted here says " no modifications", i understand that to refer to steerong only, how hard would it be to switch to b hex receivers over to an a body and have firm feel make up some custom a body tb's?
Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
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Re: Circle Track suspension and steering advice
[Re: TC@HP2]
#1285776
08/15/12 04:46 PM
08/15/12 04:46 PM
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Joined: Jan 2003
Posts: 27,480 So Cal
autoxcuda
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So Cal
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I think Firm Feel will make you a 1.24" A-body T-bar. Whats the coleman hub rule? Is that a specific hub? What part number? Sounds like that place puts a lot of load on the right front. -makes sense if it's the fastest 1/4" bowl You could control the roll with shocks too. Do the shocks have to attach to the factory points and method or can you weld bungs to LCA and roll bar? Run a FMJ spindle on the right front for most camber gain. Can you run the rebuildable Howe upper ball joints? If so might experiment with the taller pins for more caster gain when starting with 5 deg max static. Run fitted Delin bushings for smoothness with no binding. " Non-remotely adjustable spring spacers are allowed." So this means weight jacks are allowed? What are the specific engine rules? Any picture of the suspension of some of the cars that are competitive in the class right now?
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Re: Circle Track suspension and steering advice
[Re: jcc]
#1285777
08/15/12 04:48 PM
08/15/12 04:48 PM
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Joined: Jan 2003
Posts: 27,480 So Cal
autoxcuda
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So Cal
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Quote:
Seems to me the biggest hurdle is tb size. I run both a and b/e bodies never noticed the hex sizes are different. The rule quoted here says " no modifications", i understand that to refer to steerong only, how hard would it be to switch to b hex receivers over to an a body and have firm feel make up some custom a body tb's?
Hex sizes are the same A to B/E. With 1.24" being the biggest diamter T-bar to fit that Hex.
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Re: Circle Track suspension and steering advice
[Re: autoxcuda]
#1285778
08/15/12 07:30 PM
08/15/12 07:30 PM
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Joined: Jan 2003
Posts: 5,394 Pikes Peak Country
TC@HP2
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The rules say 1965 or new American cars, 108" minimum wheel base 3200 pounds minimum.
Well, that's wide open. So, do you have to sign up to request a rule book? I don't see any links on their web site for rules.
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It is Slinger Super Speedway. The fast qualifier lap time was a bit less than 14.5 seconds last week.
Wow, 9.908 track record. That is stinking fast in a straight line, never mind going around corners.
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You could control the roll with shocks too. Do the shocks have to attach to the factory points and method or can you weld bungs to LCA and roll bar?
Run a FMJ spindle on the right front for most camber gain. Can you run the rebuildable Howe upper ball joints? If so might experiment with the taller pins for more caster gain when starting with 5 deg max static.
Yes, shocks will help slow it down, but with that much loading, they will give up travel part way through the turn. With the other restrictions, I'd assume you must maintain all stock mounting points for all suspension positions.
The FJM spindle and tall joint is a decent idea for camber gain. However, with the banking you generate less body roll and more suspension compression so the camber gain may not be as big a help as it would be on a flatter track.
The biggest C body bar Firm Feel will make is 1.24, other wise I'd suggest maybe using C body sockets and stepping up to something even bigger.
Maybe, just Maybe, you could talk to a company making t-bars for chevy trucks and see if they could make a step up bar with the 1.24 socket and a 1.38 bar. Could get pricey though.
Herein lies the biggest issue of running a competitive mopar oval track car. On a flatter oval you may be able to get away with a big bar, soft spring set up, but on a banked oval your just sunk for lack of rate.
Is it Allpar that has the oval track forum? I know there is a fairly active one out there somewhere, but I haven't visited for a while, so I forget who it is. They may have some ideas of how to work around the lack of rate.
In any case, knowing what the fastest cars are set up like and running for rates and shocks would be a big help in creating starting point.
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Re: Circle Track suspension and steering advice
[Re: TC@HP2]
#1285779
08/15/12 08:31 PM
08/15/12 08:31 PM
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Joined: Jan 2003
Posts: 260 Slinger WI
MadMez
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Slinger WI
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Thanks for all the replies guys! I looked up the Coleman hub, I think what they are refering to is for the GM fellows. http://www.colemanracing.com/Hub-Aluminum-GM-Mid-Size-P3550.aspxI emailed the track for the rules and they sent me a Word document. I do not know why they are not on the web site. This class is intended to be a lower cost way to race and the rules say you cannot do much modification. I will talk to some of the racers and see if they are willing to share some information with me. I will also visit Allpar and do more web snooping to see what I can find. Moparts is my default stop! Thanks again everyone.
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Re: Circle Track suspension and steering advice
[Re: Winchester 73]
#1285783
08/16/12 11:43 AM
08/16/12 11:43 AM
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Joined: Jan 2003
Posts: 5,394 Pikes Peak Country
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Moparchat is where quite a few Mopar circle track racers hang out.
Moparchat, thank you Brad. That's what I was thinking.
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sorry ,i say dumb things-why not use a travell limitter on the lca and wind the bar tighter against it?seems like a good way to stiffen up the right front.i bet the PHD guys drill me on this
also you can play with the length of the sway bar ends to get more swaybar out of the same size bar.
also if you like cheeting-couldent a sneeky racer make a swaybar act as an auxilary torsion bar buy welding it solid out of teck sight?
With the downforce of the banking, you wouldn't want to limit travel to gain rate. Bottom out the suspension, your rate goes to inifinity and the car skates up the turn into the wall.
Changing the lever arm length of the sway bar can manipulate its rate, but with stock mounting points, you can only have two lengths of arms and the roll rate of the sway bar won't help with compression on the t-bar. Banking inhibits roll and promotes downforce. That's how the speeds get so high on banked tracks.
Considering a 9.90 e.t. at the drag strips has a trap speed of 135 mph, once you factor corners into things, the record setting car at Slinger had to be up around 145-150 at the end of the straights before throwing it into a 90* corner. The banking to hold that much speed smashes the suspension down unmercilessly, even in a light weight 1800# sprint car.
Even at the Thunder class times of mid 14s, the 3200# weight limit is going to require some pretty high spring rates to hold up the additional compression even though the speeds are lower.
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Re: Circle Track suspension and steering advice
[Re: MadMez]
#1285785
08/16/12 12:44 PM
08/16/12 12:44 PM
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Joined: Jan 2010
Posts: 1,442 NW Chicago suburban area
Mopar Mitch
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Good luck with the track and car setup.. I raced my Challenger there -- at Slinger -- with a Wisconsin autocross club about 30 years ago. at that time, my Challenger was running F/Stock with the SCCA Solo II program. Its a fun high-banked race track... with an infield to also run on.
Mopar Mitch
"Road racers and autocrossers go in deeper and come out harder!"... and rain never stops us from having fun with our cars... in fact, it makes us better drivers!
Check out MOPAR ACTION MAGAZINE, August 2006 issue for feature article and specs on my autocross T/A!
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Re: Circle Track suspension and steering advice
[Re: MadMez]
#1285787
08/16/12 05:03 PM
08/16/12 05:03 PM
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Joined: Nov 2008
Posts: 1,491 Lethbridge, AB, Canada
dangina
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Quote:
I have done a litle bit of research and the the GMs use front coils with a spring rates of 750 to 1000 lbs/inch. I seem to recall a factor of 2.2 (?) between the spring and wheel rates for those cars so the wheel rates would be 341 - 455 lbs per inch but that could be wrong, does anybody know the ratio between the spring and wheel rate on GM G bodies?
The stiffest FirmFeel bars are for an A body at 370 lbs/inch. Those are 1.18 diameter. 1.25 bars in the a body length would be stiffer but that math is beyond me.
Here is my goofy idea. The shock absorbers must fit in the stock mounts. Could a coilover shock fit that would add more spring rate than the available T bars can provide? Or is that just crazy?
Thanks!
I think magnum force is the only one that makes coilovers fit your stock strut towers, when your into coilovers the sky is the limit for spring rates - I run 10k on my drift car which is 560lbs, I've seen them as high as 14k which is about 784lbs!!
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Re: Circle Track suspension and steering advice
[Re: MadMez]
#1285789
08/17/12 12:58 PM
08/17/12 12:58 PM
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Joined: Jan 2003
Posts: 5,394 Pikes Peak Country
TC@HP2
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I'd have to go back and try to find my notes on my set ups, but I seem to recall that the GM arms I used were either just shy or just over a 50% motion ratio for the springs. I'd imagine metric chassis are similar, but may not be exactly the same as the earlier F and X body stuff I was using. 50% is a close enough ball park to say a 800# GM spring is a 400# wheel rate.
I know a 1.22 41" B body bar is 400#. Not sure what a 1.22 37" A body bar would be, but it would be higher. Of course, with a 3200# minimum weight requirement, this would give the nod to an A body potentially being more competitive than a B body.
When you say coil over, I assume you are talking about a clamp on coil overload assist and not an actual coil over racing shock/spring combo. The former is a band aid for loads, the latter a component specifically outlawed by the rules requiring stock, make to make suspensions utilizing OEM pick up points. Yes, you could clamp one of those overload units in place, however, the shock tower is not designed for that amount of loading so eventually you will bend something. I also assume they do not provide rates on any of those so it is a swag on what amount it will help. There is a motion ratio involved with the shock mounting locations, so if they claim a 500# load capacity per inch, it may only provide an effective rate increase of 50# at the tire contact patch. Will that be enough to help, maybe. However, you still have tech inspection and rules compatibility to deal with and if the overload spring is the crutch that makes you competitive, I'll put money on it being made illegal after your first main event win.
Turning a sway bar into a torsion bar is an interesting trick that could be effective. The mounting would present certain challenges since you cannot clamp a round bar tight enough to provide a consistent spring action. The hex ends on FJM cars was huge to absorb the leverage produced. I suppose a hex mount inside the K frame to match the t-bars hex would work, but then you would need to bend the opposing end to simulate a sway bar and mount in a manner that won't deflect. That might work for a while. I'm also not sure how that would impact roll couple percentages since you could then radically alter it from side to side. Eventually, someone will figure it out and again, likely outlaw it.
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