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This topic was originally posted in this forum: Modified Tech Talk
Author Topic:   4link/zlink question
driver27
Member
posted April 29, 2004 06:33 AM     Click Here to See the Profile for driver27     
I have a 4 link z link rear mod and was wondering if everyone else is extremely loose on corner entry off the gas? It really is almost as if the rear end skates up the track when off the gas and slightly on the brakes. Only way to control it is to roll into the corner much sooner than I would prefer. How do you know when your rear springs are too stiff? Currently running 250 lr and 225 rr with lr in front and rr behind. Track gets very hard and rubbers up by main event time. Any help appreciated.


de94wcc
Member
posted April 29, 2004 08:23 AM     Click Here to See the Profile for de94wcc     
We have actually had just the opposite problem, way too tight in. Have you checked your brake bias? Sounds like you have a little too much rear dialed in. Do you run the LR clamped/unclamped in front? Maybe you should try running LR unclamped behind, and the RR in front or maybe even on top of the rearend. What is your rear percent? Perhaps you are a little light?


driver27
Member
posted April 29, 2004 09:12 AM     Click Here to See the Profile for driver27     
Have been running about 57.5 rear percent with the driver in. Brake bias I dont think is the problem as I can change the way the car enters by using it, to the point that I can actually lock up the front whees if too aggressive. Is everyone running the rear square, or putting some lead in? By the way, everything is unclamped and mounted on the birdcages. Left spring in rear, right spring in front. To get decent entry I have to run practically no bite in left rear (without driver), so it makes the car loose off.

After reading my 1st post, I had the springs wrong, lr is behind, rr is in front, sorry.

zeroracing
Member
posted April 29, 2004 09:39 AM     Click Here to See the Profile for zeroracing     
read post below

[This message has been edited by zeroracing (edited April 29, 2004).]

NJantz
Member
posted April 29, 2004 10:14 AM     Click Here to See the Profile for NJantz     
Yeah I have the same problem. So I'm taking Zero's advice and putting on a stiffer LF spring. I also put some more angle on my RR brake bar.

My LR spring is behind on the cage and RR spring is in front on the swing arm. I'm running longer 4bar links than most peeps.

[This message has been edited by NJantz (edited April 29, 2004).]

[This message has been edited by NJantz (edited April 29, 2004).]

zeroracing
Member
posted April 29, 2004 10:38 AM     Click Here to See the Profile for zeroracing     
i have a short upper link 4 bar, long lower.
i am clamping my rr spring behind the axle, so it will tighen up all over the track.

as far as driver 27, i would consider clamping the rr spring behind the axle, this will tighten the car up all over, then lower your rr reaward facing trailing arm. this will free it up off the corner.
if you do that it should tighten up entry, and almost be a wash on exit, so not effect it much.
also boost up the lf spring to tighten up entry, or lower rf. lowering rf will also free up exit.


Majic Maker
Member
posted April 29, 2004 10:45 AM     Click Here to See the Profile for Majic Maker   Click Here to Email Majic Maker     
I would put the lr on a clamp bracket in front of the rearend and put the rr on top of the rearend,also i would even up the split between your front springs.


WPP
Member
posted April 29, 2004 04:15 PM     Click Here to See the Profile for WPP   Click Here to Email WPP     
How does the car react when you put the spring on top of the right rear differt then the spring clamped behind thanks


dirtbuster
Member
posted April 29, 2004 04:23 PM     Click Here to See the Profile for dirtbuster   Click Here to Email dirtbuster     
With the spring on top it doesnt react to rotation of the axle housing when getting in or out of the gas. With the spring in front on the right rear it loads on the gas and unloads off the gas. Behind on the RR it loads off the gas and unloads on the gas.


WPP
Member
posted April 29, 2004 06:04 PM     Click Here to See the Profile for WPP   Click Here to Email WPP     
So on a dry slick track with the spring on a clamp on the rear it loads up off the the gas and tighten the car on entry and unloads on the gas to tighten you up off the corner.When infront it loads on the gas and unloads off the gas this could make you loose on a slick track.Then when the spring is on top it just there no loading and you still are only useing the left rear for all the bite if you are clamped on the left rear infront while on the gas. If i can see things clear here a spring clamp behind will act almost like a spring on top of the rear when you exit the corner the only differce is on entry. When is the best time to run the spring infront only when there is bite or tacky track thanks for the help


Majic Maker
Member
posted April 30, 2004 10:29 AM     Click Here to See the Profile for Majic Maker   Click Here to Email Majic Maker     
Wpp your 100% correct on the spring behind clamped up on the lr rear its neutral it just holds the car up! The spring in front of the lr clamped up is good on a tacky track or dry slick it works good on either! The spring behind the lr works good too it works off of body roll its more less driver preference!


WPP
Member
posted May 01, 2004 06:45 AM     Click Here to See the Profile for WPP   Click Here to Email WPP     
Magic Maker what i was meaning when is the best time to run the spring infront on the right rear Just when the track has bite. It looks when you run both springs infront you would have to have a real good track to stay on the the throttle because when you back out it unloads both rear springs if you could stay on the gas it could be a good set-up and keep the car tight . This is my first try with the spring clamped infront on the 4-bar and the spring on top of the z-link right the right rear spring is infront we have two tracks one you can stay in the throttle more one you can not should i run the spring on top on the tighter track and in front on the faster track if there is bite thanks


Majic Maker
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posted May 01, 2004 05:52 PM     Click Here to See the Profile for Majic Maker   Click Here to Email Majic Maker     
Wpp I would run the spring on top on the rr at any track no matter what the conditions are or how big the track is. As far as the lr goes the spring on on a clamp bracket in front of the rearend will work either way but you will problay see an advantage if you use it on a stop and go track rather than a track that you stay in the throttle, the spring behind the lr on the birdcage works great on a big track that you stay in the throttle!!! Hope this helps?



WPP
Member
posted May 01, 2004 08:19 PM     Click Here to See the Profile for WPP   Click Here to Email WPP     
When i told you the right rear was clamped the spring is on top of the rear and i still can move the spring infront with the bracket i have. Is this any differt than having a clamp bracker below the rear. I hope i did not confuse you. What spring rate would you start at on both sides and how much differt in spring rate with the clamped lr and changeing to the spring behind thanks


Majic Maker
Member
posted May 02, 2004 04:44 PM     Click Here to See the Profile for Majic Maker   Click Here to Email Majic Maker     
Wpp I understand now what you have on the rr i had a slight misunderstanding on the last post!! With the spring in front on the rr its helps with forward bite and its different than having the spring on a clamp bracket, because of the mounting points of the springs and the way it plants the rr tire! Im not trying to tell you what to do but from my experience with this the spring on top of the rearend on the rr is the best way to go! As far as the spring rates go I change springs and panhard bars from a tacky track to a dry track. For the tacky track i run a 150 on a clamp bracket in front of the lr and 200 on top of the housing on the rr and a panhard bar behind the rearend. When the track dries out i put a 200 on a clamp bracket in front of the lr and leave the 200 on the rr on top and put a short bar in front of the rearend.With the spring on the birdcage behind the lr I ran a 200 all the time.I also go from 30lbs of bite to 150lbs when the track changes.Hope this helps!



uforacing51
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posted May 04, 2004 10:26 AM     Click Here to See the Profile for uforacing51   Click Here to Email uforacing51     
I ran a 4/z last year for the first time on a Harris and had so many problems with it I finally took all of the lead out of it and it ran great. What I mean is this:
the 4 bar under acceleration moves the LR tire forward, in the corner your car should have the RF tire ahead of the LF and the LR ahead of the RR, thus helping the car turn. I couldn't drive it very well that way, I made it so the LR only moved forward enough to even the rear and I ran 1st two weeks in a row. I also had the springs at LR 200 and RR 150.
this year is exactly how harris set it up: spring in front on RR and in back on LR, we'll see how that works soon. Good luck with it, as one racer put it "a 4/z is a hard set up to be learning on"


driver27
Member
posted May 04, 2004 11:03 AM     Click Here to See the Profile for driver27     
So a 250 on the lr in front and a 225 on rr in back may be a bit too stiff? Im thinking of dropping 25 pounds each side and trying that. Also, im gonna make a clamp bracket for the rr, put spring in back and try that one day. Any idea on starting point for a spring rate if you go that rout.


zeroracing
Member
posted May 04, 2004 11:26 AM     Click Here to See the Profile for zeroracing     
"Wpp your 100% correct on the spring behind clamped up on the lr rear its neutral it just holds the car up!"
actually when you clamp the spring behind on the lr you are making it unload under gas and load under brake, it will make the car very loose.


WPP
Member
posted May 04, 2004 05:31 PM     Click Here to See the Profile for WPP   Click Here to Email WPP     
There are alot of differt spring rates people are running i think most of it is what tires you are running with imca tire i think you can go softer but what i run is ump tires i think you can go a little bit stiffer. What do you guys think. I was thinking about starting with 225s across the rear 800 lf 750 to 800 rf this ia a dw but i will also have a 200 ready for the right rear magic marker has been a big help thanks


STICK01
Member
posted May 11, 2004 07:50 AM     Click Here to See the Profile for STICK01   Click Here to Email STICK01     
WPP,

On my DW8 4-bar car that is very close to what I ran this past weekend, 750 LF, 700RF and 225's on the back, then changed to a 200 RR for the feature. Car worked great sticking on the bottom, middle, and top wherever it needed. Just looking for a little more off the corner. We put the car back on the scales last night and had 45LB or RR in it? How I am not sure yet, but we are working on it, as we went to the track with 60 lbs of LR in it.

STICK


WPP
Member
posted May 11, 2004 04:36 PM     Click Here to See the Profile for WPP   Click Here to Email WPP     
Keep the %% the same with the 45pds rr switch you front springs with the 750 on the right front and move the pull-bar to the left little at a time until you like it off the corner.


Ego Racing
Member
posted May 11, 2004 05:45 PM     Click Here to See the Profile for Ego Racing   Click Here to Email Ego Racing     
Driver27 Where is your J-bar mounted? Try lowering the pinion mount lower and dont get to aggressive on the bar angle.


driver27
Member
posted May 13, 2004 07:35 AM     Click Here to See the Profile for driver27     
the panhard bar is a short one mounted on the left. it is about an inch or so above the pinion centerline, with 2 inches of rake. Im thinking of dropping it a hole to even with centerline and tryin 2 inches of rake again. Sound good?


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