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Author Topic:   Rear Spring Split???
FlyNLoIMCA17
Dirt Forum Champ
Total posts: 753
posted June 30, 2004 04:36 PM  
I was wondering what kind of rear spring split most of you guys were running, just curious. I'm running 50lbs. I'm gonna change it to 25lbs. this weekend. Just wondering what to expect. Oh yeah its a 4 bar car. Springs LR-250 RR-200. Progressive spring pull-bar. Gonna change LR to a 225. Car just doesn't have enough bite out of the turns. Pullbar has 20* of angle on it. Car is good everywhere else. Just need more bite. Tried moving the 4 bar and it helped but not enough. Thanks for any help you guys can give me!

Dale

2nd2none
Dirt Forum Champ
Total posts: 755
posted June 30, 2004 05:12 PM  
how much rear % you have?

nvracer
Dirt Maniac

Total posts: 127
posted June 30, 2004 05:32 PM  
How much LR bite is in the car?
Lacking bite is it loose coming off, Tight in the middle?
How much rear %?
Need more info.
Lowering the spring rate will not improve forward bite. It will probably reduce forward bite.

FlyNLoIMCA17
Dirt Forum Champ
Total posts: 753
posted June 30, 2004 06:40 PM  
I have 56% rear and if I remeber correctly its about 90lbs LR bite. I know that dropping spring on the LR supposedly reduces bite, but last year I ran the car with the 225, I got to run only one full race. The car drove like it was on a rail on a dry slick track, on the last lap a car bumped me and spun me out, another car hit me head on and bent the frame. So the car builder cut the metric frame out from under it and installed another one(yes it was jig built) When I got it back I thought I'd change to the 250LR to give it more bite, but it seems like less than it had before. I had heard somewhere that too much split would cause it to lose bite off the turn and thought maybe I went too far?? Just wondering what you guys thought?? The car is good everywhere else, going in, through the middle, and its not loose coming out to where I can't control it, it just lacks forward bite, an acceleration loose if you will. Its running consistently about 5th place, just looking for a little extra to get me to the front. Thanks, Dale

FlyNLoIMCA17
Dirt Forum Champ
Total posts: 753
posted July 01, 2004 12:19 AM  
ok I searched through the archives and found something interesting, rear spring location. I have the LR behind the axle and the RR in front of the axle.......from what I read that is backwards from what I originally thought. I was told that the way I had it would produce more bite coming out. I guess I never really thought about it. The LR 4-bar video on here really helped b/c the spring unloads on accel. So I guess I'll change that and put the LR in front and the RR behind........maybe that will work?????

rocket36
Dirt Freak

Total posts: 209
posted July 01, 2004 01:08 AM  
don't do that. leave the left rear spring behind and the right rear spring in front, both floated on the birdcage.

2nd2none
Dirt Forum Champ
Total posts: 755
posted July 01, 2004 11:30 AM  
the reason to run the LR behind on a 4 bar is because on initial throttle the spring is being compressed and it helps the car climb the bars.

It looks like you need to increase rear %. go up to 58% and try that, if still loose add more weight if too tight take some out. Rear percent is a huge facter in getting foward bite. The bar angles are a timing effect.

FlyNLoIMCA17
Dirt Forum Champ
Total posts: 753
posted July 01, 2004 04:35 PM  
ok guys thanx, I'll try mounting some lead in the rear, thanks for the help!!

FlyNLoIMCA17
Dirt Forum Champ
Total posts: 753
posted July 01, 2004 06:22 PM  
one more question regarding the LR spring location, if I shouldn't put it in front of the axle then why when you clamp the LR do you put it in front of the axle?? Also what will it do if I leave the LR in behind the axle and move the RR behind the axle also??? I trying to learn all this so I'm sorry if I'm bugging the heck out of you with stupid questions.

Dale

boas51
Dirt Maniac

Total posts: 190
posted July 01, 2004 07:31 PM  
a lighter lr spring will allow the car to climb the bars quicker, and should tighten the car.
if your springs are mounted to the birdcages, because of indexing (the rotation of the birdcage through chassis roll) the lr will unload slower if it is mounted behind, and the rr will load quicker if mounted in front.
i moved my rr from in front to on top of the housing with a load bolt and it seemed to improve forward bite. from what i have heard moving the rr behind on the birdcage makes the car too tight.
if the lr is clamped, mounted in front of the diff, with a spring/rubber pullbar or a lift bar, it will compress when the diff rotates under power, and add bite.

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