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Author Topic:   Rear steer with a z-link
msnead
Dirt Forum Racer

Total posts: 77
posted July 19, 2005 08:40 AM  
Our car has been a bit on the pushy side, especially in the middle of the turn.

I've been told by more than one person that running a z-link RR will "take away all of your rear-steer"...

Since we are running a 4-bar LR, can I compensate for the reduced rear steer on the right side by adding some into the left? If so, how do I accomplish this? Which bar(s) do I move?

(We already added about 1/4" of static rear steer to the car before the feature and it made a world of difference.)

Thanks,

M

Xtreme12x
Dirt Forum Champ
Total posts: 874
posted July 19, 2005 08:46 AM  
IF you go TOO far on rear steer on any suspention, the car will start to push the front end up the track. I have had that problem for weeks now, so I lengthened my LR trailing arm (2 link) but am running it at the same amount of uphill angle. A Z link will "pin" the RR harder, which will make the car tighter. What you might want to try is moving your Z link bars around a little. You get the rear steer out of the Top bar on a 4 link, so the principal is the same on the Z link, but we tend to angle the bottom bar on the z link uphill quite a bit at ride height and let the rearward facing bar sit about level to 5-10 degree's downhill from the rearend.

Kromulous
Dirt Forum Champ
Total posts: 796
posted July 19, 2005 09:01 AM  
LR, move the bottom bar up one hole.

The Z-Link statement is inaccurate, you can get lots of rear steer with a Z-link, and you can get zero if you want. This is why its popular i believe, you can make a car super tight, and then super loose real easy.

I remember another post by you talking about the mount on the rear bar on your Z-link, and how you cant get it to go much past level. You cant get downward angle in it.

That needs to be fixed, adding angle in that rear bar, down ward angle, will help generate some rear steer as well. Plus take some drive out of the RR, which may be the true issue.

If its pushing in the middle, i would also consider stagger. Adding another .5 to 1" of stagger, with the same LR bite number should do the trick.

dirtmod0
Dirt Maniac

Total posts: 143
posted July 19, 2005 10:52 AM  
dropping the top bar adds right rear drive to that tire. and adds rear steer.

Camaro_Dude_1991
Dirt Maniac

Total posts: 104
posted July 19, 2005 11:00 AM  
quote:
Originally posted by dirtmod0:
dropping the top bar adds right rear drive to that tire. and adds rear steer.

Your right, i posted that wrong above, it would add drive to the RR, making it feel looser off.


msnead
Dirt Forum Racer

Total posts: 77
posted July 19, 2005 08:54 PM  
I tried to reply earlier and the site went down and I lost my post...so, I'll try to remember what it said.

Before I go into the actual discussion, let me recap the race on Saturday: We went out onto a tacky track for hot laps and had a really bad push in the middle of both turns. To remedy this, I made 2 changes...

1. Before hot laps, I bought a new LR tire and forgot to let all of the air out so the LR was way too big--meaning 0 to + stagger. I'm sure that didn't help our push any.

2. Upon the advice of another DirtWorks racer, I added "static" rear steer to the car. In the feature, both changes seemed to make a world of difference because we went from 13th to 7th in 2 laps. A caution and a flat tire took us to the back. When I put a new LR tire on, I suspect that the stagger was wrong again because it got a little "pushy" after that. All in all we didn't do too bad since nothing major got bent this week.

Kromulous, you make several good points... I think stagger was to blame for part of our problem...the car wasn't as free as we would like it but it drove much better when the stagger was set right...especially at the apex--the car seemed to rotate better.

The other point you made was about the top bar on the right... You're right...I am only getting 1 degree of downward angle in it right now. The DirtWorks guy (I forget names) mentioned that it may be that the ride height was set incorrectly in the rear meaning that the bar can't get any more angle... So, I checked and he is right, the car is too high in the back. I just didn't have time to reset the ride heights and rescale it before the race. I'll do that this week.

Thanks for the advice so far...now, my new questions are:

1. When we add angle to the top bar on the RR (the "Z" bar), will that be enough rear steer to notice a difference? How drastic of a change will it be?

2. I moved the bottom right bar up 1 hole before hot laps to try to add some rear-steer--what did this do (we didn't notice any difference on the track) and should I put it back?

Thanks again!!!

m

rpm20
Dirt Freak

Total posts: 338
posted July 25, 2005 05:29 AM  
quote :
2. I moved the bottom right bar up 1 hole before hot laps to try to add some rear-steer--what did this do (we didn't notice any difference on the track) and should I put it back?

in reply to this, i will tell you that you moved the bar up and never reset your bar length so the rearend is in the same as it was before the change , then you took rearsteer out when you moved it up and in the corner you didnt notice a change because of 2 reasons 1. you shortened the wheelbase on that side (tightened the car slightly)
and 2. the lower bars mainly effect corner exit handling. while the uppers effect entry mainly

so what you did is took out the static rear steer you put in earlier and ended the same as you had it before.
had you lengthened your bar when you moved it up then you would have seen a difference.

measure distance from rearend to frame and restore that distance after you move the bar up or down. ( we use a plumb bob)

msnead
Dirt Forum Racer

Total posts: 77
posted July 25, 2005 07:59 AM  
The reason I moved the bottom bar is because on the 4-bar (both sides) car I help out with, moving the bottom right bar up was supposed to add rear-steer and moving it down was supposed to take it away. (This was the advice from the car builder...) We would move the bar up when the track was wet/tacky and back down when it dried out. I figured that on our z-link RR it would do the same thing.

Since someone replied to this post, I'll update everyone on what happened this past weekend: Lowering the car in the rear, which allowed us to have some downward angle in the z-link bar helped loosen the car up considerably. We qualified 9th out of 23 cars...not bad for our 3rd race.

During the feature, the track went from tacky to dry-slick almost instantly. (Which is odd because we were the first feature and there weren't any late models this week...)

To make a long story short, our driver lost it in the dry stuff (or was it the slick stuff?) and spun the car out. Then, another driver who apparently didn't see him hit us head on (he never hit the brakes) and literally drove over top of our car. The frame doesn't look like it took that much of a hit... The front suspension and sheet metal is trashed, though. (The other car came to a rest on top of our car--when our driver climbed out of the car, he hit his head on the back bumper of the other car.)

One thing I can praise is the safety of these cars...

Ok, I know I've asked this before, but I'll ask again: Other than ordering from DirtWorks, where is a good place online or by phone to get parts from? I need swaged tubes, upper a-arm collars, ball joints and a shock. I don't have a problem with DirtWorks but I'm on the east coast and it takes 3-4 days to get something from them. I'd rather have it take 2-3 days if possible.

Thanks for the replies...

m

[This message has been edited by msnead (edited July 25, 2005).]

Kromulous
Dirt Forum Champ
Total posts: 796
posted July 25, 2005 09:54 AM  
Do you have a Poske's catalog? Dave Poske's performance wharehouse i believe. There in West Virginia and carry most anything you'll need. They can get things to me in Cincinnnati Ohio in 1 day, or 2 max.

1-800-430-Race, is the number.
http://www.poske.com/

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