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Author Topic:   4-bar / z-link bar lengths
de94wcc
Dirt Forum Racer

Total posts: 87
posted September 02, 2004 11:41 AM  
All else equal, what are your opinions about what bar lengths should be from center of heim to center of heim. I'm getting ready to start building a new car for next year but I think I need a little tweak on the rear suspension. We've been running about 15 1/2" on top of 4-bar, and 13" on bottom bar. 13" on both z-link. Thanks for any replies.

dirtywrench13
Dirt Freak

Total posts: 324
posted September 02, 2004 12:23 PM  
I'D THINK YOU'LL WANT A FULL 2 TO 3 INCHES AT THE LEAST TO GET THE BIRD CAGES TO INDEX RIGHT.

CUSTOMPERFORMANCE
Dirt Forum Champ
Total posts: 1172
posted September 02, 2004 12:31 PM  
Were running 14" on the lower and 16" upper lr 4 bar and 15" lower and 20" upper rear bar z side. Car is very fast.

[This message has been edited by CUSTOMPERFORMANCE (edited September 02, 2004).]

de94wcc
Dirt Forum Racer

Total posts: 87
posted September 02, 2004 12:41 PM  
That's what I suspected. I think I'll plan to add at least another two inches all the way around. Thanks for the replies.

NJantz
Dirt Forum Champ
Total posts: 755
posted September 02, 2004 01:47 PM  
de94wcc:
My left rear 4bar is very close to your dimensions. My top rear zbar link is probably around 26 tho.

OX54
Dirt Newbie

Total posts: 3
posted September 02, 2004 06:27 PM  
Can anybody tell me how far the bird cage should index when the car is up on the bars, full throttle. Should it still be straight up and down or should it be indexed back or forward, thanx.

zeroracing
Dirt Forum Champ
Total posts: 1875
posted September 02, 2004 08:36 PM  
i run 20 on the bot and 15 on the top. it makes the car index a ton. on slick tracks you waant as mcuh indexing as you can without giong over center.

de94wcc
Dirt Forum Racer

Total posts: 87
posted September 02, 2004 09:34 PM  
The main problem we are having right now is that the car is up on the bars so quick and so hard, I think the spring is just hanging there anyway. My thought is longer 4-link bars might slow it down some. It seems every car I look at has longer bars than us. I'm very interested in your comments on the z-link lengths. Why the longer bar on top in the rear? Does it "lever" the spring more on the RR to increase bite at that corner?

zeroracing
Dirt Forum Champ
Total posts: 1875
posted September 06, 2004 04:14 PM  
i would also like to know the reasoning behind the longer upper bar on the z link. if you have a shorter upper link then the car will increase bite on that side more, it will increase indexing(so if you are running spirng in front) but it will increase rearsteer. so what are the reasons behind the long upper.

CUSTOMPERFORMANCE
Dirt Forum Champ
Total posts: 1172
posted September 06, 2004 05:41 PM  
short lower on z side for bite and longer upper rear bar to keep rearsteer to a min on the right side.

#13 mod
Dirt Full Roller

Total posts: 72
posted September 06, 2004 06:41 PM  
We have been running harris's 4/z this season. It took awhile to get everything working well, but I can tell you that we do adjust the 4link bars, shorter or longer, to match the track conditions through out the night. I guess what I'm trying to say is don't get stuck on one lenght just because someone says that it works well for them. Remember that a shorter lenght for any bar on the car will react quicker and you should be good to go.

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