XelderX's BG FSP Build
- Thread starter xelderx
- Start date
The first event will just be an evaluation of the suspension. I'm running a completely opposite springrate setup on the 1st Gen from the 3rd Gen. The swaybars are attached different from what I'm used to and they will be a different ratio front to back. I could be doing a lot of springrate changes over the first few events so I'm not really putting any major expectations on finishing position. Jinx Jordan (2nd place FSP 2007) is at all my local events so I do have a good target to aim for. He is flying this year. He came to last weekend's event on the new 255-13 and set FTD/FTP. He out paxed 2nd place by 6/10ths and that was the 2007 DS ProSolo Champion. On the surface it seems like there is no way I can compete, but Jas00x was only 1 second back from him at Nationals last year and my car should be faster than his when it's finished.
The only two things left that are not just bolt-on affairs are the exhaust and the ECU/wiring. Boswell still has my ECU, but he should be very close to finishing it. I'm ordering the header next week, but I'll have to have it modified before I can install it. The header I'm ordering doesn't have a large enough inner diameter pipe after the secondaries come together. With the smaller pipe it will reduce some top end power. I'll need to cut that off and weld in a new larger flex pipe and straight pipe to the cat. None of that really bothers me at the moment. The next big hurdle will be the wiring, ECU, and getting it to talk to the FS motor through the BP harness. If I can get the motor to run properly everything else should be a piece of cake.
Vanimaniac
Member
Jeez, Justin. You are working like crazy on that thing. I admire that. My brother and I have done half of what you've done and we've had our SP car for 3 years now. Eg. we've run one set of springs from day one.
Hoping to be running FSP with you next year.
Van
ps. Any pics of the new 255/13's? How much faster can you guess Jinx is going on the new tires?
Hoping to be running FSP with you next year.
Van
ps. Any pics of the new 255/13's? How much faster can you guess Jinx is going on the new tires?
It looks to be around .5-.7 seconds, but he did say that the car can be faster with a few more adjustments.
Vanimaniac
Member
Cool. And that was over the 225 Hoosiers correct? So if I could put the 225 Hoosiers at 0.3-0.5 secs faster than the 215 V710's maybe I can expect to go a sec faster? Hmm. I'll have to see. Three cars from our region trophied in FSP last year (BMW 2002, Scirocco, Pink Golf). We are in range of the last two, still a ways back from the BMW. The scirocco is going to the 255's soon and has a new national caliber driver so you'll have him to contest with this year.
Anyways, I'll be rootin' for you!
Good luck!
Van
Anyways, I'll be rootin' for you!
Good luck!
Van
We were at 455/370 and are now going to 550/370 on the STS ZX2. It was just too loose...like 'driving on ice' loose.
I'm starting out with 600f/450r...since that is what I had laying around and it's close to Will's magic ratio of 1.25:1 roll ratio. We'll see what happens.
What's this roll ratio you speak of?
I might be calling it the wrong thing. I'm trying to recall an email from memory that Kalman sent me a few months ago.
He tried a lot of different front to rear spring rate ratios and found that the BG chassis responds best to a 1.25:1 ratio with all the other suspension stuff he had. He tried a 1:1 ratio and found that the car wanted to push. I'll quote the email when I get home this evening. I have it saved.
gavin_leslie
Member
Unless I miss my mark, Wills Escort had a shorter wheelbase than the sedan you have. You may find that with that difference and the fact that you will be running R-compounds (much more so than Will ran) you might want/have to change those ratios a bit
Will had a post on RR-AX about what you are speaking about and went into detail about the spring/roll ratio.
EDIT: found it
Gavin
Will had a post on RR-AX about what you are speaking about and went into detail about the spring/roll ratio.
EDIT: found it
wkalman - 2008-06-16 5:37 PM
It is my opinion that reducing traction on either end of the car is a Bad Idea unless you are absolutely out of other things to do or up against the limits of the rules - or you're desperate to try anything just in case it works.
Typically, the hot setup for FWD is to add rear roll stiffness but I believe that a given chassis has an optimal F:R roll resistance **ratio** and anything outside that optimum is "less" overall. Once you find this optimal ratio, you can raise or lower the total stiffness, adjusting shock rates as appropriate and make small adjustments to things like camber, tire pressures, and toe. Note this is Total Roll Resistance, springs and bars included (and shocks to a lesser degree and then mostly in transistions).
A case in point was my STS Escort GT. I was doing very well with 250F/200R springs but then decided to take it up a notch. Along with some GC AD struts valved for the application, I went 500/500 - a 1:1 ratio compared to the 1.25:1 ratio I had before. The results with this new, more-rear-biased springing? Push! The reason was that I'd gone outside the optimal F:R ratio for the chassis. I was lifting the inside rear (remember, it's stiffer vs. the front now) moving the rear roll center to the contact patch of the outside rear (as Nate alluded to), which diagonally loaded the outside front = push. Putting 600# springs on the front solved the problem by putting my ratio at 1.2:1, much closer to the 1.25:1 that worked so well before.
That was on struts where less body roll always results in less camber loss. On a double-wishbone suspension like yours, you may find that a higher or lower **total** roll resistance puts you in the sweet spot of your car's geometry or at least in a place where you balance the suckage front to rear.
Ultimately, unless you go to a F/R staggered tire setup, FWD is going to push in a steady state corner. Outside of a staggered setup, the trick is to get a car that allows you to trailbrake/lift throttle steer it into corners - **predictably**.
And extreme example is our HS '07 Civic - We're leaning WAY over into the outside front while trailbraking into a turn (as much as the stock ABS will allow) and really extending the inside rear suspension. We're hoping to fix it with a bigger front bar - straighten up the car and reduce the *diagonal* loading. Conventional wisdom says that we need more rear stiffness to get the car to rotate but that would be completely the wrong direction for us. Our F:R ratio is not nearly optimized from the factory.
Gavin
It wasn't "roll ratio" he was referring to. I got two different emails from him confused. We were talking in another email about running stiffer springs on the rear like I ran on the Pro5. He was explaining that he tried that and the weight transfer diagonally across the chassis caused a bad mid-corner push. The way he explained it made sense even though it was completely backwards from my experience with the Pro5 which never pushed.
Quoted from Kalman...
What struts/springs/rates are you running? I've found that a 1.25-to-1 ratio F:R to be ideal (with the bars I'm running).
My old suspension was with four-way adjustable Maxdaspeed struts 250F/200R. Then I went to the Advance Design struts and did 500/500 and found that the rear was too stiff relative to the front, causing mid-corner push. Then I went to the current 600/500 setup (1.2:1) and it improved a lot.
The only problem with the setup now is fighting wheel spin because of the lack of an LSD and because it's so stiff that any uneveness in the surface causes a diagonal weight transfer which makes one front wheel light. But I assume you've got a good LSD in your setup.
Also, David Avard and I found that lowering the car too much causes all the awesome turn-in to go away. Keep the suspension arms level. But if your suspension is stiff enough, it may not affect you that much, we discovered it when we were both running 250/200 springs. I haven't tried it on my current stiff setup becasue I need the suspension travel due to strut length.
Quoted from Kalman...
What struts/springs/rates are you running? I've found that a 1.25-to-1 ratio F:R to be ideal (with the bars I'm running).
My old suspension was with four-way adjustable Maxdaspeed struts 250F/200R. Then I went to the Advance Design struts and did 500/500 and found that the rear was too stiff relative to the front, causing mid-corner push. Then I went to the current 600/500 setup (1.2:1) and it improved a lot.
The only problem with the setup now is fighting wheel spin because of the lack of an LSD and because it's so stiff that any uneveness in the surface causes a diagonal weight transfer which makes one front wheel light. But I assume you've got a good LSD in your setup.
Also, David Avard and I found that lowering the car too much causes all the awesome turn-in to go away. Keep the suspension arms level. But if your suspension is stiff enough, it may not affect you that much, we discovered it when we were both running 250/200 springs. I haven't tried it on my current stiff setup becasue I need the suspension travel due to strut length.
Damn Gavin...4 minutes quicker.
Yea...that post is basically the long version of what we talked about. There are several large differences between Will's setup and mine, but I'm just happy to have a good baseline to start with, especially since I was about to start with the springs completely backwards from his setup. It normally doesn't take me very long to setup a car the way I want now that I've setup the Pro5 and know what I want the car to feel like.
I went and double checked. Wheelbases are listed to be the same. My staggered wheel setup and tire compound should be the only big differences.
gavin_leslie
Member
Same wheelbase for the escort and the protege? How odd. Even with the GD chassis for the 626/mx6 the chassis was shortened 2" for the coupe. Thats pretty cool though that you done get a "long wheelbase" penalty.
whoa....Does AWR have the individual pieces for those endlinks. I see a project to do.
Gavin
whoa....Does AWR have the individual pieces for those endlinks. I see a project to do.
Gavin
Call up Tony at AWR. I'm sure he can work something out with you. The ends are from the rear Mazda3 fitment he sells with a longer center shaft. I installed them today and they work perfectly, but I'll probably cut them down about an inch shorter. They are just a hair longer than I need them.
