Need help in design.
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Thread: Need help in design.

  1. #1

    Default Need help in design.

    I am currently designing a fox body mustang to build after my army tour in Korea is over (May). First off I will be running NASA.

    Design:
    8.8 IRS (out of a tbird) tubular a arms and coil-overs on all corners
    302 carb engine aluminum heads forged rotating assembly t-5 transmision
    nasa approved cage
    tubular diff and tubular k member with redesigned tube strut mount for proper coilover travel etc.
    the car will be completely gutted with fabricated dash and solid steering column
    I am thinking wheel travel will be around 9 inch's on all fours

    Is there anything I am missing to be legal in 2wd open and anything in my plans I can not do?

    Also I need help on spring length and rate Also over all coil-over length. Shock rebound and compression rates.

    What gearing do you guys usually run?

    Me and my dad have built plenty of race cars and my dad is a mechanic by profession however this will be our first rally build I am expecting the build to take a year or so. Any and all input would be greatly appreciated. I want to have the design hammered out by may so I can begin work when I settle in at Paso Robles CA.

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  3. #2
    The Scorpion King John Sundelin's Avatar
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    First off, not to start off on a negative note, but I've never understood why anyone would say that are only going to run one sanctioning body or the other. Organizers choose which sanctioning body they are going to run for a variety of reasons, some of them very good, some of them petty. In my mind, the quality of the event is vastly more important than who sanctions it (if anyone). Besides that, if you build a car for only one sanctioning body and you decide you don't like/can't afford to compete in it, you've limited the market for the sale of the car quite a bit. On top of that, if you are living in California, the nearby events are split about 50/50 between sanctioning bodies.

    Now, to the specifics of the car, I am not familiar enough with Mustangs to understand the implications of "solid steering column", but if that means a solid piece between the steering wheel and the steering rack, that would be a really, really, bad idea. People used to get impaled on steering columns all the time before automakers came up with collapsing columns. In the design of the car, you should think about how things are going to respond in an "off road excursion", because they will happen.

    I think you are more likely to run afoul of the California smog laws than the rulebook. Just something to keep in mind. I don't see anything problematic about what you are proposing, though I haven't read the latest NASA rules for displacement, and keep in mind that NASA Rallysport West events have typically used the California Rally Series rule book for classes. Suspension dimensions are probably going to have to wait until you've got everything mocked up, but if you can really get 9" of travel, you should be in good shape. As for gearing, if you are going to use rally tires, they are typically only rated for about 120 MPH for a reason. There have been rallies where cars got up to about 140, but that's generally considered a really bad idea. There is one section at Prescott and one section at Seed 9 that I can think of where a very fast car might be able to exceed 120, but if you target that for your max speed, I don't think you'll have a problem. The number of Mustangs is fairly small (3 or 4?), so the experience base is somewhat limited, but the people who have built them are good sources of information. Locally, Bill Holmes runs a Ford Raptor (ok, it's not really a Raptor because of the smog laws), and Jim Morris used to run a 3rd gen Camaro, which was basically the Chevy equivalent of what you are thinking of. It sounds like it will be a lot of fun to drive when you are finished!

    --
    John
    Last edited by John Sundelin; 12-02-2013 at 10:35 AM. Reason: Gene's right...

  4. #3
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    Quote Originally Posted by John Sundelin View Post
    First off, not to start off on a negative note, but I've never understood why anyone would say that are only going to run one sanctioning body or the other. Organizers choose which sanctioning body they are going to run for a variety of reasons, some of them very good, some of them petty. In my mind, the quality of the event is vastly more important than who sanctions it (if anyone). Besides that, if you build a car for only one sanctioning body and you decide you don't like/can't afford to compete in it, you've limited the market for the sale of the car quite a bit. On top of that, if you are living in California, the nearby events are split about 50/50 between sanctioning bodies.

    John


    Completely agree, build the car for both. Even if you dont run it itll hurt potential buyers if you ever sell it. It's like 5% more work at most making sure you're legal for both series.

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  6. #4
    don't cut
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    NRS West does not use CRS rules for anything. The only big issue one may run into between NASA and RA rules is cage construction. NRS allows a couple of configurations that RA frowns upon. We can easily guide you thru that. Springs and such may be a bit harder and depends somewhat on how you configure the suspension. Those answers can be found also.

    Gene McCullough
    NRS/RA western scrutineer
    Olympus co-chairman

  7. #5

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    not knowing anything about the t-bird IRS, why not run a solid axle with a long 4-link setup? http://www.doublegmotorsport.com/rsp...nsion-Rear.pdf

  8. #6

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    I agree with the both sactioning body thing. and by solid steering column I am replacing the stock one with a solid round piece of steel to a cuick release it will travel through an adjustable ball bearing connector. It enables you to build the shaft how you like and add in a quickener if you like. The reason for the IRS is it is better suited for rally and also I just want to say I have done it.

    thanks for the responses guys I am planning with the cage builder now to begin work as soon as possible.

  9. #7

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    Can someone give me a pros and cons list for 4link and IRS?

  10. #8
    The Scorpion King John Sundelin's Avatar
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    Quote Originally Posted by heymagic View Post
    NRS West does not use CRS rules for anything. The only big issue one may run into between NASA and RA rules is cage construction. NRS allows a couple of configurations that RA frowns upon. We can easily guide you thru that. Springs and such may be a bit harder and depends somewhat on how you configure the suspension. Those answers can be found also.

    Gene McCullough
    NRS/RA western scrutineer
    Olympus co-chairman
    Oops... What I wrote was not what I thought I wrote, so I fixed it to say what I thought I said. To the OP, if that doesn't make any sense, 4 of the 5 currently scheduled NRS West events this year are also in the CRS, so there are effectively multiple events going on at the same time with different classes.

    On the subject of 4-link vs. IRS, I will only point out that there is a downhill towards a bridge at Prescott that is a great test of suspension. I first ran the event in 2003, and frankly don't even remember the downhill (my Focus has IRS). Last year I ran fast sweep in my truck (long story), and was getting very concerned that we might end up in the small canyon at the bottom.

    --
    John

  11. #9
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    Quote Originally Posted by bwhit16 View Post
    I drove dirt track prior to joining the Army almost all of my cars and parts are sold now but I am looking to get into Rally I got dizzy doing left turns. I have learned a lot driving for years on dirt (from the age of 4 in karts) and one thing that is apparent is throttle control can make or break someone in a higher horsepower car. The reason I am going with the 302 is I have an engine builder (family friend) who has more knowledge of smallblocks then he does of 4 bangers and also I have parts built of for spares. And that is also the same reason I am building a foxbody I have raced them before and I have spare parts I know them in and out and I know how the chassis will hook up with good bad and ugly setups (sometimes you get stuck between a rock and a hard place but need points for a series) Plus I want to have a hand in something unique.

    OK so you have Foxies on hard, that is always a good thing---if the car isn't a real POS like some tiny 86" wheelbase thing..

    Look I's been a Ford engine builder for damn 33 years now, all Furrin Fords, like made in Germany or made in Brazil but I know SBF (hell I'm using SBF 5.4" eagle rods with 2" Chevy journals in my lttle 1963cc (German) Ford V4)....
    Your guy doesn't have to know anything special about the 4 cylinders like the 2300 SOHC (which most 'Merikun Frod guys call "Pinto" and I call "Squinto" (if you kinda squint at it--and ignore the obvious stuff----it sure looks like a Pinto) but is really called the "Lima" motor--built from '74 onwards in a brand new plant in Taubaté, SaoPaulo state in Brazil... they are tougher in everything by far compared to SBF (talking stock here--buigger rods bigger oil pump, STOUT mainline in the block etc)

    I say to guys looking for either the Xerrti or 240: If it has oil pressure, call it good...
    Much more important in rally is to get the RIGHJT: suspension
    Steering
    Brakes
    final drive---to match the motor
    gear set---to match the motor

    And if possible: LIGHT WEIGHT which makes all those things easier..

    Whatever a little motor doesn't make for ft/lbs, the axle ratio does..
    We ---those who are smrat and buy cars that they CAN chose---use short axle ratios from (depending on tire dia) 4.6 to 5.45:1 cause 99% of what we're doing is coming out of a corner around 25-30 mph at the slowest and zingin it up to about 90, again and again and again..

    No need for building a hot V8, no need for the power, no ned for sure for the weight.
    None of the few insane high HP guys are any faster because of that than prettty tame normal shit...

    OK solid axle---done with LONG likes advatagesd: its good enough and the wheels are always 90 degrees to the ground.. Good enough for the best rally car in the part of the Galaxy: Ford Escort MkI and MkII, good enough.
    Just long links (which make for slow arcs when doing long travel, and slow arcs means reduced axle tuggin and pushing and pull..

    IRS: better ride...yep that's it. Ride is nice but every single gawddam IRS set up is invariablt goofy in wheel movement, often--usually weak junk, but wait, usually heavy..
    Yep like we used to say "Well pardner, it aint strong but at least it ain't light" Sheeeeeeeut.

    True story-bro-back when everybody (factories) were all in RWD several ditched the IRS and went to solid axle.....with long links like in the link Bopocapolys or apackolips posted. It did fine on both gravel AND tarmac..

    So if you had sumpin that came IRSed in the first place like these Xratties (which just happen to have 2300 Turbo Limas too) then OK run it, but if the thing is solid axle now, do a right 4 link+ panhard and get some travel in it... ther is NOT a lotta grip and we get grip by letting the bugger squat down....and by being smart with power and power delivery.
    John Vanlandingham
    Sleezattle, WA, USA
    www.rallyrace.net/jvab
    www.rallyanarchy.com

    Telephone +1 206 431 9696
    Rememeber the time zone difference

    Vive le Prole-le-ralliat

  12. #10
    400 flat to crest
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    Quote Originally Posted by John Sundelin View Post
    Oops... What I wrote was not what I thought I wrote, so I fixed it to say what I thought I said. To the OP, if that doesn't make any sense, 4 of the 5 currently scheduled NRS West events this year are also in the CRS, so there are effectively multiple events going on at the same time with different classes.

    On the subject of 4-link vs. IRS, I will only point out that there is a downhill towards a bridge at Prescott that is a great test of suspension. I first ran the event in 2003, and frankly don't even remember the downhill (my Focus has IRS). Last year I ran fast sweep in my truck (long story), and was getting very concerned that we might end up in the small canyon at the bottom.

    --
    John

    Then again that might be something about the vileness of pick-ups, balloon-osis tires probably on pick up , maybe a hundred other factors--just maybe, possibly, maybe.
    John Vanlandingham
    Sleezattle, WA, USA
    www.rallyrace.net/jvab
    www.rallyanarchy.com

    Telephone +1 206 431 9696
    Rememeber the time zone difference

    Vive le Prole-le-ralliat

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