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Author Topic:   Just scaled car
Rat Trap
Dirt Maniac

Total posts: 129
posted March 12, 2005 12:36 PM  
We just scaled our car using the bathroom scale method. Total cost to make them $40

Heres what we got, we are going for more of a dry slick set up on a medium banked 3/8

With driver,
LF 630lbs
RF 395
LR 735
RR 710

Left side 55.26%
Rear 58.5%
Cross 45.75%

20 gallon of fuel
without the driver the left side and rear percent was a bit lower, but cross was higher.
Are we at a good starting point?

dirtmod0
Dirt Maniac

Total posts: 143
posted March 12, 2005 01:08 PM  
looks good but the rf seems pretty low

Xtreme12x
Dirt Forum Champ
Total posts: 874
posted March 12, 2005 01:36 PM  
RF and lr are too low and too much left/not enough cross

justin
Dirt Freak

Total posts: 263
posted March 12, 2005 03:59 PM  
Definately add some more cross into it. That should help bring your LR and RF wheel weights back up. I'd shoot for around 51-52% and fine tune it up or down from there.

Justin

Xtreme12x
Dirt Forum Champ
Total posts: 874
posted March 12, 2005 04:10 PM  
48.5 to 49 cross

Rat Trap
Dirt Maniac

Total posts: 129
posted March 21, 2005 02:48 PM  
We are new to making the adjustments needed. I'm bumping this back to the top to see if i can get somemore help. We took the car out yesterday and it ran and drove pretty good except for on entry and middle, it had a bad push. Exit and straights were great.
If you read the top post you will see that our RF weight is way too low and our cross is low. What/where do we adjust to correct this. We can see (we video taped our practice also) that the right front is dipping alot but the front of the car just don't want to turn on entry.
Some other info on our car is its a 3 link.
springs:
LF 700lbs
RF 750lbs
LR Slider infront 225lbs
RR Slider on top 200lbs

Ride heights:
LF 5 1/2"
LR 5 3/4"
RF 6"
RR 6 1/2"

Our shocks are all 94's, We know we should change some of our shocks, but i have read from you guys that we don't necessarily want to do that till we get the other stuff right.
We are also wondering if our ride heights are way to low. Of course we can play with all of this on the scales and we will, but would like to know which way to go and where to start so to speak, Thanks guys you are tons of help and i hope i can get to where i can help others as you have helped me.

FlyNLoIMCA17
Dirt Forum Champ
Total posts: 753
posted March 21, 2005 03:47 PM  
Your right on the shocks. Get the car close to handling right before you mess with the shocks. They are for fine-tuning and will not fix a big problem.

Your Left side % is WAY high. The more banking a track has, the less left side % you need due to the downforce produced by the banking.

Your cross is too low try for around 48-50% like what Xtreme said.

The more cross you have, then the car will free up going in. With that much LF weight I don't see how the car is tight???
Also you only have 25 lbs of LR bite. Try for around 75-100 and if you need more bite coming out then add more.

I know you said it was good coming out but don't worry about that right now. You always adjust the entry first. Fix the tight in problem and then worry about what effects that has. Is the car "skating" up the track on entry or is the front end pushing straight up?? Does it feel like the car has any side bite??

dirtbuster
Dirt Forum Champ
Total posts: 2007
posted March 21, 2005 04:04 PM  
flynlo,
His left% was with driver, didnt know whether you caught that or not. Thats prob not far off, maybe a little high yet though.

Teh ride heights dont look too bead depending on the car. What kind of car is it, have you checked with the manufacturer?

Without driver Id shoot for 52-52.5% left, 58 or more rear, and aroudn 50-75#LR. springs should be good, shocks are good except maybe could got a little stiffer in front like 5 valves. While its true shocks wont fix a bad car, the wrong shocks can also make a good car seem really bad.

Was the tightness in the middle rolling to the middle or after you start to pick up the throttle?

It was prob tight on entry because of the low cross. Up the cross and that should free the car up more on entry and into the middle up to the point you gas it. If its still tight soften the LF spring a little.

Rat Trap
Dirt Maniac

Total posts: 129
posted March 21, 2005 04:25 PM  
if i get that left side % down is that going to increase that RF lbs? Logic tells me it should.

The push/tight is in the entry / middle of the turn. Its doesn't seem to have the skating feeling as you mention. The front wheels are turned and the car goes still goes up the track, unless i really get the car slowed way down going into the turn.

It is an old buddy mullens chassis. I don't konw if anyone is familiar with them or not. This is my 2nd year in a mod. So i do realize alot of it is driver, but i don't feel that is all it.

To change the left side and add LR bite, is it just a matter of adjusting jack bolts or is it adding and moveing lead around?

I reread a couple of the responses, the push i believe is going to the middle when i start to pick the throttle back up. I'm trying to explain it the best i can. If i don't back way off on the throttle and brake hard it doesn't get to the middle. I tried braking just in the straight and in the straight going into the turn with close to the same results.

[This message has been edited by Rat Trap (edited March 21, 2005).]

Kromulous
Dirt Forum Champ
Total posts: 796
posted March 22, 2005 06:24 AM  
Can you move the fuel cell? or do you have any weight you can move around on the car? maybe a battery or something?

You need to move some weight to the front and to the right. Your rear percent looks high, and the left side is high. Try to find some things to move around until those two numbers are in the 52% range for left side weight and about 57% rear.

Then start adjusting for cross and bite.

Add fuel, put the springs you want on, and set the ride heights. If one corner is low on weight, turn that jack bolt in 1 turn on that corner, and out 1 turn on the other 3 corners. Contnue this procedure until you get the numbers you need.

Also there are two ways to do it, with driver in, or out. Either way be consistent on how you do it, also you can use some type of ballast in place of the driver.


irace74
Dirt Forum Racer

Total posts: 80
posted March 23, 2005 07:40 PM  
I concure with everything which has been stated previously. I would try to get some of the weight off of the left front. It looks to me that you can wedge the front of the car and get to where you generally need to go. If you put 2-4 turns in the RF, take 2-4 out of the lf and put 1 -4 in the left rear I think your numbers will come right in. The ride heights in the front should not change very much but the wedge will. By adding 80 # to the lr, and adding 80 or so to the rf, reducing the left front, I think you will achieve the balance you are looking for. The ride heights look ok I think that the rr is a little high for a car with the driver in the seat I would expect the rf and the rr to be nearly identical with the driver in the seat. Further, the left side should also equal out when the driver is in the seat. I typically look for 5 1/2 on the left side and 5 3/4 to 6 on the right.

flyin353
Dirt Full Roller

Total posts: 49
posted March 24, 2005 06:24 AM  
I always shoot to get the front springs balanced. As other people on here have said, take 4 or more turns out of the LF and put the same amount into the RF and your weights should all come around without changing your ride heights. Looks to me like the car, how you have it now, would push like a truck going in and would be terrible loose coming off. If you are racing on real dry slick tracks I would reverse your front springs...I run 850 LF and 800 RF.

JMO

racer 4
Dirt Forum Racer

Total posts: 77
posted March 24, 2005 06:50 PM  
i dont know what you run for wheel offsets i would guess you are probably in the area maybe a 2 off r/f and 4 off l/f try moving the right front in a couple if you can and move left front out a couple if you can.this will add r/f take out l/f and add cross .to often we get carried away cranking on the screw jacks. i suspect if your front split is that far off it will take more than cranking weight around and upsetting your ride heights. other things may be tire size, air pressure, be sure your scaling on a perfectly level surface, and always bounce your car a couple times to be sure your springs are completly set in the spring pockets. good luck.

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