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Author Topic:   3link-loose,and no foward bite
chapa73
Member
posted March 21, 2004 06:00 PM
At practice today under dry conditions and tacky the car was very,very loose,with NO foward bite.I was running 1/2" of stagger in the back.Its a 2link with a rubber biscuit for the lop link.I havnt scaled the car yet,and if it would help you guys then I can get some frame hts.I was looking at the mods today and alot had alot of pinion angle in them.I dont have alot of pinion angle.
I run a strait pan bar behind the rearend,mounted on left side of chassis.
What are some things I can do to get the car to hook up better without making it radical,today was the first time I had drivin a mod.
I have 200lb springs across the back.I was thinking more angle on the lower links,maybe some more pinion angle?Its an old flexi flyer kit car with some modifacations to it.

Any advice on getting the car tighter under accleration and wopuld be great.

Xtreme12x
Member
posted March 21, 2004 06:10 PM
without scaling it you'll never get it close to fine tune
you could have a lack of rear percent, lack of cross
put all the angle you can in both your rear bars upward, what kind of angle is your pullbar at???
also if you have too soft of a right front spring you will have no foreward bite
get the car on some scales....


chapa73
Member
posted March 21, 2004 07:44 PM
The pull bar is at abuot 20 degrees downhill.
What kind of numbers should I be shooting for once I get it on some scales,hopefully that will be this week.I have the Mod chassis technology book from Steve Smith,but those numbers seem to be quite a bit different from the talk on here,what Iv heard and varous setup sheets.

Thanks

Ego Racing
Member
posted March 21, 2004 07:55 PM
Those number are a starting point to get you in the ballpark. Every driver will like the car a little different. Scale the car and get the hard numbers. Post them then you will be able to get the help you are in need of. You could just raise the banhard bar and it will tighten it up and get you some bite off but if the car is off on springs and shocks it could just put you in the wall!!


dirtracer14
Member
posted March 21, 2004 08:06 PM
Is the rear staight with the front? What size fuel cell is in it whats the wheelbase is the panhard centered on the rear side or is it up or down of center? What offset wheels did you have? What chassis is the front end...metric? whats the front spring rate? How much shock travel did you get? Do you have a spring bar you could try....what tires did you have? What type motor and gears? If you could shed some light for us im sure we could get you a little closer ....untill you can get the scales!


Chad
Member
posted March 22, 2004 10:50 AM
All the questions posted by Dirtracer14 are important and you should determine the answers to those. You need to know your starting points. But, often times, especially for new modified drivers, their cars are actually too tight and they think they're too loose. Obviously if the chassis isn't set up correctly you'll need to address that first, but you'll need to think about what the car's doing as you enter and set for the corner. If you have to steer too much to the left to get it to turn the car will have a tendancy to snap loose once the front tires bite. It takes experience to determine this, but I run across guys all the time that complain their cars are loose when they encounter this situation. Usually the car snaps loose as you're applying the the throttle and it catches you with the wheel cranked to the left. Just something you should be aware of, but get the chassis straightened out first and answer all of Dirtracer14's questions and the guys on the Forum with get you in the ballpark.


chapa73
Member
posted March 22, 2004 05:45 PM
okay thanks for the repleys,here is what I got,less front springs,dad cant remember what they are and thay are not stamped.

75 chevelle frame-metric spindles,adjustab;e uppers,chevelle lowers.

Frame hts were meseared at the front were the frame starts to go uphill to the aframes,the rear was measured at the square tubing that is run to the bacl of the car that the rear hoop welds to,thats about level with the bottom of the stock frame thats its welded to.
lf-5.5" rf-7"
lr-6" rr-6.5"
Wheel offsets:
lf-3" Rf-2"
LR-3" RR-3"
American racer G-60 tires:
LF-78 RF-79
LR-80 RR-80.5
The pan bar is mouted on the right side of the rearend,at this time its bolted slightly lower than the axle tube,mount on the left side of car,I dont have an angle finer here,but measured distance from floor up on both ends and here is that measurement:

Right side,bolted to rearend-11" from ground
left side(bolted to frame)-12",so not alot of angle

It didnt take alot to get the car to rurn,I did notice that when I hit the brake it took off to the right,I dont have a brake bias guage,I need one Im sure,but it seemed to me too much front brake.?
shock travel:
LF-2" RF-2.25"
LR-2.5" RR-2.5"
Shocks:
LF-76 RF-76
LR-95 RR-96

Its a 350,small dome pistons,48#scat crank,re-man rods,462 heads,2.02 valves,power plus intake,MWM-8 cam.
500 gear.
rearend is strait with the trailing arm mounts,but that prolly dont mean its strait with front end im sure,tips on doing that i could use!
cars total wight at track with about 3/4 load of fuel and alittle mud was 2560.

Thats all the info I got right now,im hoping to get it scaled this week,and get down to a raceshop and get the front springs checked.

If it helps I was practicing at State Fair Speedway in OKC

dirtracer14
Member
posted March 22, 2004 06:58 PM
check the rear end off the front grese zerks..drop a plumb bob off the zerks and off the rear of the car. the rr spring seems stiff to me....from shock travel and mayby a bit stiff on the shock. Now withthe car weighing that im gonna guess its got a 22 gal fuel cell unless you are a light driver? How long are the trailing arms on the right and left? I would put more angle in the panhard and maybe a 2" off on the lr and a 4" off on the rr. These are all things to look at but if i were you i would check the rear and make it square...then if the track is dry put a 175 or a 150 spring on the rr. The rf also seems a tad high on ride height. I am just tossing a few things out there but if this is you first time in a mod get the rear done and springs close and just drive the car were it feels good to you....just drive you own car dont worry about the guys around you so you can get the feel and be able to remember what the car was doing when you get in the pits and make a change to go forward. The other thing is what size track are we talking? 1/2 mile or what? 5.00 gear? How many rpm did you turn?????? Not spinning rpm but driveing rpm?


chapa73
Member
posted March 22, 2004 08:05 PM
its a small 3/8,in my factory stock I would want to pull a 690-710,I normally run a 740 ona 1/4 and at the other 3/8 I run a 679.
Alot of the guy si talk to say they run a 523 there,I was prolly in the 7000 rpm,My peak was 7300 on the last session of practice wich was my better run.I forgot to mention its a 32 gallon fuel cell.
18 " on the trailing arm,the rod end to rod end.Tomorrow I will check for sure.
No spring loaded pull bar to try,is that somethign I should really look into,and if so what type and what kind of angle?

Thanks very much for all the info,this furom has the greatest folks.

dirtracer14
Member
posted March 22, 2004 08:48 PM
You are running a 5.00 on a small 3/8?


zeroracing
Member
posted March 22, 2004 10:01 PM
The track I plan on running is bigger and a buddy that runs there told me a 500 works well,it was a small 3/8 we were at sunday,just trying to get the time in the car.
Thanks Zeroracing,dirtracer14 and everybody for the advice. As far as the wheel spin,on my best run i dont think i was into the 4 barrel till almost the entry of the corner,I was staying with the pack of cars then.

as far as nothin but RR bite,im not really for sure,A few times under alot of throttle in the middle of the strait,the rear would jump out from under neath me,it felt like wheel spin,but also I dont have alot of seat tim ein it either. I know with my factory/street stock i never had to baby the throttle that much enless the track had stabding water and and in the 1st heat,I know thats 2 completly differnt cars,but just trying to get all the info i can,I know that some of the problems I was and am having is me,as some of the "handling' problems went away be the end of the day.

Now I just need to figure out the quick steer,IM used to cranking on the steering wheel!!!

Thanks guys.
Ill let ya now sunday how things work out!
goodluck to everybody this year.


16Again
Member
posted March 27, 2004 08:47 PM
try 94s on the rear


xhubby
Member
posted March 28, 2004 09:16 AM
When my son started racing mods, we took a white tire marker & colored in several 3-4" wide patches on the sidewalls of the tires, (from the rim to the tread), to help get an idea how much wheel spin he was getting compared to the front wheels. It wasn't rocket science, but it gave us an idea. It also helped to set tire pressures, as we could see how much the tire was rolling over in the turns, by how much of the tire chalk was rubbed off.


chapa73
Member
posted March 28, 2004 05:43 PM
wow,I nevee really thought of that.Thanks for the input,with these mods there is so much to tune with than with the stocker.I re-set my ride hight,squared the rearend,well actually I made the left side 1/4" shorter,put more pinion angle in it and at the track I planned to run at this year the car really worked good,track was pretty dry and it had alot more foward bite,only a few other mods there so I didnt have much to judge from but we could run just as fast as they were.

THanks again for all the input from everyone

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