Visit The Dirt Forum for More Information

Author Topic:   Tight in Apex
hasben
Dirt Full Roller

Total posts: 26
posted April 25, 2005 01:11 PM  
Our rear suspension is 4link on lr and z-link on rr. As soon as the driver gets on the throttle he picks up a push. We have trailed the left rear to try and eliminate the rear steer. It has helped some but I would prefer to have rear end square in the car and not have the push either. Need help!

jdj9410
Dirt Full Roller

Total posts: 65
posted April 25, 2005 02:23 PM  
Tried 4/Z link first of year and had same problem. Could get it to turn with 47% cw and about 80-90 lb left bite. Was inconsistent though go from push in middle to loose in middle. Fixed it by going back to 4/4 link. Gonna try it again at some playdays later. Maybe some of the 4/Z guys on here will help out.

nyimcamod8t
Dirt Full Roller

Total posts: 67
posted April 25, 2005 04:47 PM  
alot of variables here, where are your springs and what bar angle are you running?
kinda confusing me on trailing the LR. why would you take away rear steer when the car is already tight in the apex? generally tight on apex would indicate you need either more steer or less bite on the LR.

nvracer
Dirt Maniac

Total posts: 127
posted April 25, 2005 06:47 PM  
I was also wondering why trail the LR, If anything I would trail RR.
A few Ideas reduce LR bite, Increase stagger, Raise LR bottom trailing arm up a hole (To increase roll stear. Lower LR Upper Trailing Arm Down a hole (reduces forward bite on the LR).
So many things can improve this, shocks, springs, J-bar (panhard bar).

hasben
Dirt Full Roller

Total posts: 26
posted April 25, 2005 07:05 PM  
We wound up trailing the lr by trial and error. Where we have it works the best. Left upper trailing arm about 16 degree uphill. Lower trailing arm about 5 degree uphill. This has proven to be optimum for us. Spring lr is 175 and rr is 250 on swing-arm style z-link. 650 lf and 750 rf on a metric chassis. j-bar is in bottom hole on pinion mount and about 5" up on chassis. Would lengthning the lower trailing arm help? The top trailing arm is 16" long and bottom is 14" long. 140 of bite in lr,xw51.8

dirtee1
Dirt Full Roller

Total posts: 28
posted April 25, 2005 07:42 PM  
I would take the bite down to about 70 #"s

hasben
Dirt Full Roller

Total posts: 26
posted April 25, 2005 08:55 PM  
tried that. car won't come off the turn without spinning out or real slow. by then the rest are gone

boas51
Dirt Maniac

Total posts: 190
posted April 25, 2005 09:14 PM  
jbar up on the pinion

Mastersbilt05
Dirt Roller

Total posts: 21
posted April 25, 2005 09:22 PM  
You could move your pullbar over to the right a little bit more unless it is already over there but I am like nvracer there are alot of different things that you can do to fix this.

nyimcamod8t
Dirt Full Roller

Total posts: 67
posted April 26, 2005 03:20 PM  
work on getting the car thru the apex of the corner and then work on exit.sounds like you have the car tightened right up for exit when alot of the problem being loose off is due to a tight apex. having the car exiting the corner good is useless if you can't turn it in the middle.first thing i would try is raising the j-bar on the pinion side and running a little less split.could prolly get away with a little less lr bite then also. is your lr spring on the birdcage behind or clamped in front?

washeduptoo
Dirt Maniac

Total posts: 155
posted April 26, 2005 06:04 PM  
LR spring is on bird cage behind. Thanks

nyimcamod8t
Dirt Full Roller

Total posts: 67
posted April 27, 2005 03:07 PM  
the spring behind is good.doesn't sound like the setup is too far off, just snug in the center. try raising the j-bar, that should free up the center and still allow you to get off the corner good.

hamer36
Dirt Maniac

Total posts: 196
posted April 27, 2005 04:49 PM  
what springs are in the car? You could lower the rr Z arm. This would put more bite into the RR when the car rolls and you pick up the throttle, and also give a little more rear stear which should help.

droper23
Dirt Freak

Total posts: 233
posted April 28, 2005 06:28 AM  
We fought the same problem. We took off the top bar on the RR and welded the birdcage solid to the rear end. We then got the CW to about 49 % with about 30lbs of LR. Cars drives a lot better now, it is a little loose mid to exit but I can deal with that over a heavy push.

melracen
Dirt Newbie

Total posts: 1
posted April 29, 2005 08:28 PM  
you've got your rear springs backwards. The left rear spring should always be heavier than the right rear spring.

zeroracing
Dirt Forum Champ
Total posts: 1875
posted April 29, 2005 09:13 PM  
His rr spring is on a swing arm z link, so it is not that 250 rate by the time it hits the wheel. And spring rates depend on balance of the car and track conditions, on some heavy tracks i put alot of rr spring in the car to get alot of drive.
I agree 75-80% of the time or more the lr should be stiffer than the rr but sometimes it will work better for different tracks the other way around. also with it on a swing arm the spring is not going to be as stiff as that 250 rate.

washeduptoo
Dirt Maniac

Total posts: 155
posted May 01, 2005 07:58 PM  
Thanks for the information. He moved the pullbar all the way to the right and moved the j-bar up on the pinion. The car was really fast in the hot laps and handled pretty good, broke in the heat,got it fixed, track went slick for the feature and we didn't have any side bite or forward bite with this set up. Back to the drawing board again, going to try a 300 spring on rr and go from there. Keep the information coming. Does anyone know of a book or a guide on the 4-link z-link setup. I have something on the 4-link, just want to know more about the z-link. Thanks again.

holeshot
Dirt Maniac

Total posts: 119
posted May 01, 2005 10:29 PM  
I had this problem and what fixed it for me was raising my pull bar up. I had too much angle and when I picked up the gas it would be tight and then loose. when I moved it up it took bite out but carried the bite it had further thru the turn and down the strait.

Xtreme12x
Dirt Forum Champ
Total posts: 874
posted May 01, 2005 10:57 PM  
washed up
to get that side bite back, simply move that pull bar back over to the left and drop the j bar down on the pinion again. You should probably get that pull bar over to the left as far as you can and leave it, then tune the side bite with the j bar...

Start with what you've got, only move that pull bar over. Another thing you might try in the heat when the track is heavier (when the push would occur worse), is put a 3" off set on the rr if your running a 4" right now. If you've got a 3" on there right now, get yourself a spacer and put big studs in there. With the Pull bar to the right it is giving up some side bite, but not a lot. It is also giving up the lr drive and putting it on the RR.

Back to the Archives