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Author Topic:   Help with forward bite
Racer17V
Member
posted June 27, 2000 02:19 PM
My car handles great, goes in great, but coming out I have no forward bite. The car is straight, but just rings the tires. We have a 3 bar car with sliders. The LR has a 200# spring, 94 shock, RR 150# spring, 93 shock. The lift bar has about 1" preload on it with a 175# spring. The panhard bar runs downhill about 1" in hopes of getting the car to roll over. Any ideas? We were going to put a softer spring on the lift bar, say 150#. I understand we have a lot of motor with only 8" tires, but it's really bad. The first 200 feet or so I have nothing. We were even thinking of retarding the timing a few degrees as the track is high banked and very slick. Any help would be greatly appreciated!!


jammin
Administrator
posted June 27, 2000 02:54 PM
What percentages are you running and what are the locations of your rear springs?


Racer17V
Member
posted June 27, 2000 04:10 PM
Jammin...

The LR has the 93 shock...RR 94 sorry.
The springs are located about 6" infront of the rear end on swing arms.
The track we run at is high banked 1/2 mile always dry-slick.

Setups with driver)
649-524
766-627
50.3 C 55.1 L 55.3 Rear 139# LR heavy
We have a 50# weight above the fuel cell, which is in the center of the rear clip.
We also have a 93 shock on top of the rear end.

Thanks!

jammin
Administrator
posted June 27, 2000 04:41 PM
If your running a 93 on top of your rear, that is your problem, your supposed to have a 90/10 on top. Very little extension is needed, not letting the rear rotate as needed.


Racer17V
Member
posted June 27, 2000 04:53 PM
Jammin....

we had the 90/10 on and took it off....we were having the same problems with it on.



jammin
Administrator
posted June 27, 2000 06:59 PM
Well, if you were, then something else is wrong besides the shock, you need to put it back on. It also looks like it is taking too long for the left rear to sit back down on the ground, which means that your on the Left Rear shock is holding it up too long. Lighter shock is needed so it can add pressure to the LR spring sooner. With a 55% rear weight, your gonna have to add some cross to the car to get the left rear on the ground, the combination of the shock and your crossweight are the problem.

[This message has been edited by jammin (edited 06-27-2000).]

Racer17V
Member
posted June 27, 2000 07:13 PM
Thanks Jammin....

I will let you know how things went Saturday night!

Racer17V
Member
posted June 27, 2000 10:14 PM
Hey Jammin

I forgot to ask you...what shock would you recommend I put on the LR when you say softer, and would you also recommend the softer spring on the lift bar, down to 150#?

Thanks again.

jammin
Administrator
posted June 27, 2000 10:18 PM
The lift bar spring will depend on the travel you are getting now, you want as much movement in the bar as you can get without it bottoming out. This means that it will be spongey enough to take throttle when you apply it. I would go to a 93 on a tacky track and then put a 93/5 on the LR on a dry track, this will help hold the car down on the left rear throughout the turns.


Chad
Member
posted June 28, 2000 10:40 AM
[QUOTE]Originally posted by jammin:
The lift bar spring will depend on the travel you are getting now, you want as much movement in the bar as you can get without it bottoming out. This means that it will be spongey enough to take throttle when you apply it. I would go to a 93 on a tacky track and then put a 93/5 on the LR on a dry track, this will help hold the car down on the left rear throughout the turns.[
/QUOTE]
Hey Jammin, tell him about putting the RR spring behing the rearend. Jammin helped me out by suggesting this to me, and it really hooked the car up. I was running a 406 with lots of torque, and once I put the RR spring behind the rear end, I had to work to spin the tires off the corner. Jammin, are there other changes that need to go along with the spring position change??? Possibly having to increase the rate on the torque arm??? or having to adjust the spring rate of the RR spring???



jammin
Administrator
posted June 28, 2000 11:17 AM
I was assuming, since your on a swing arm type suspension that you did not have spring mounts behind your axle, in this case you can not take advantage of housing movement in this manner. The way I do the torque arm is the same way that I just described to him on the pull bar as far as spring pressures. I want a really forgiving suspension.


MelFer
Member
posted June 29, 2000 04:52 PM
Jammin has been allot of help to most that have posted and I aggree with him The 5/3 on dry but I use 5's on the LR during heats (very heavy red clay North WI) as for the cross we have as much as 249# of bite on the LR over the RR with 59.3 rear and as fuel load decreases we will get as much as 255# bite increase. Good Luck and THANKS JAMMIN I have found the car was settling too fast for the 5/3 LR when heavy and pushin will change NOW for heats.


A2KY2K88
Member
posted July 09, 2000 01:34 PM
WHAT IS THE PROPER WAY TO ADJUST CROSS WEIGHT AS FAR AS WHAT TO DO WITH THE LF AND RR WEIGHT JACKS???????


jammin
Administrator
posted July 09, 2000 03:21 PM
You can adjust the crossweight with the LF or RR wieght jacks as well as the RF and LR weight jacks. If you increase the weight(raise) the left front or right rear, you will decrease the actual cross(wedge)(LR,RF). This will tend to set the car easier in the turns, but will make it a little looser coming out. If you increase the wedge by doing the opposite, it will tighten the car on exit and loosen it on entry with the same setup. I generally alter my cross with the LR jack as to not alter the car's front end settings from where I started. If you increase the weight on the LR, you have effectively increased the crossweight. This is more of a direct change that is easier to keep up with. No caster/camber/roll center settings to deal with on the rear as on the front. This is how I do it. Air pressure to the LR and RF will alter the cross some also. But in the same instance. If you decrease air pressure to the RR or LF, you have also increased it. There are many ways to alter it. Just making small changes and documenting what they do is what helps us be more consistent. Hope this helps.


MelFer
Member
posted July 25, 2000 12:42 AM
racer17V if you have a car that is say 2500# and you want to move 1% cross. find that no. in lbs and divide by 8. 2500X1%=25#DIV.8=3.125# per tire. place a team member at the LR scal add or subtract this 3.125 from the LR scale and start adjusting from the RR so the LR scale reads what you want + or- the 3.12#. step two again add or sub. the 3.12# on the LR scale and move to the RF make your adjustment in or out till the LR scale reads this new # the next two corners are done in the same manner with The LR being the final adjustment. You have reset the cross with no noticeable other changes to the chassis. gives you some free time. Hope this helps.


onewheel
Member
posted August 02, 2000 11:16 PM
I would suggest that you try moving your torque arm (front) to the right a little,this will allow the car to get up off the right front quicker, and get to the left rear quicker. GOOD LUCK!


6x
Member
posted August 05, 2000 09:24 AM
what is your pinion angle set at?


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