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Author Topic:   NEED SIDE BITE
DirtTrackRacingRules 3 8
Dirt Maniac

Total posts: 101
posted October 30, 2005 04:34 PM  
car doesn't get on the right rear hard enough. if the car doesn't get on the right rear i have to wait to get pointed straight to get on the gas. And also when i wait for the tail to grab the front end wants to push. But if i give it some gas then the tail is gone. 4bar on birdcage lr and swing-arm z-link rr j-bar and a pull bar around 60lbs bite and 59 tail 2 1/4 stagger

viper3244
Dirt Full Roller

Total posts: 57
posted October 30, 2005 06:25 PM  
Need Some More info. What chassis do you have? Sounds like you could do sevral things. More angle in the j-bar, wheel spacing, spring rates, etc., etc, etc, If you are close to your base set up, I would make sure your rear end is located right to left where you want it then go from there. Post more info we can narrow it down.
What size track? WHat are the track conditions? We have run as much as 3 1/2 inches on tight tacky track. And 1/4 inch on a dry slick (which gets the car pointed straight much easier.) Your problem sound like a easy fix.

rrrrick
Dirt Maniac

Total posts: 192
posted October 31, 2005 02:18 PM  
I know just changing offsets on my R/R from a 2" to a 3" offset makes a big difference in side bite

DirtTrackRacingRules 3 8
Dirt Maniac

Total posts: 101
posted November 01, 2005 03:55 PM  
its an old american made with my own tail design. As far as the rearend side to side i dont know what the meassurement should be, i just lined the lr with the lf
springs are900 1000
275 250
4 bar left swingarm z-link right
i have ran the car the same all year and its been the same except were i run weekly i can get the lf on the grass which is like a curb and it gets on the rr harder and it works a little better. im getting 4-5 inches of travel on rr so i dont want to go softer with the spring. thats a quarter mile very slick.
i went to a flat 3/8 track very slick and the car really didnt get on the right rear and the car really didnt have enough side bite. the left rear doesnt really lift either, i dont know if that is a problem. the right rear also lifts a little on the throtle, which i dont like. if i run less stagger the car will not turn on entry 2 3/8 is the least i have ran and that was this past race.
im starting to think that there could be a lot of changes needed.

20crew
Dirt Roller

Total posts: 18
posted November 01, 2005 06:39 PM  
we had to add weight [lead] on our right rear to help side bite. also ashorter bar willget it up on the bar quicker. can also soften shock [commpression ] on RR. totrnsfer weight quicker

[This message has been edited by 20crew (edited November 01, 2005).]

Modracer86
Dirt Forum Racer

Total posts: 79
posted November 01, 2005 09:25 PM  
if you are runninga 250 on the right rear that is wayyyyyyyyyyy to soft for a swingarm car i run a 325 tacky and as high as 400 when it slicks off i always run a 200 on the left 4 bar side. remember that body roll does not make sidebite i struggled with this alll year and the guys on here got me going Krom know what he is talking about when it comes to 4 bar swingarm cars but there is so many different things you can do but i would start by putting a heavy spring on the right rear

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dogwalker
Dirt Full Roller

Total posts: 65
posted November 02, 2005 09:31 AM  
If you have any angle in the right side z-link, I would recommend running them flat (or flatter). It should keep the car off of the bars on the rr anyway and should keep the car under you more on the gas. Let us know how all the responses work out for ya on the track.

Kromulous
Dirt Forum Champ
Total posts: 796
posted November 02, 2005 01:00 PM  
What do you mean when you say "getting on the RR harder" i'm not sure i follow what you mean by that?

Is the car tight out, and your trying to get to throttle steer more? Or is it loose?

Loose in, loose out?

Loose in, stiffer RR spring will help.

What kind of panhard bar you running? and what is your rules, IMCA, UMP or ?

Krom.

[This message has been edited by Kromulous (edited November 02, 2005).]

DirtTrackRacingRules 3 8
Dirt Maniac

Total posts: 101
posted November 02, 2005 02:55 PM  
its loose in center until i get the car pointed straight. this is a b-mod 2750 min weight, usra rules except weight. the less the car rolls the worse the sidebite is. the more it rolls, the quicker and harder i can get to the throttle.

im running a j-bar, about 6 or 7 inches of rake.

my z-link(back) bar is at 10 degrees up hill foward, swing-arm 1 or 2 degrees

would putting the spring on top of rearend help on rr so indexing doesn't effect spring, or will a shorty bar fix this

Thanks so much for the replys so far, keep them coming i have all winter to deside.

Also cant really try anything now the year is over.

Kromulous
Dirt Forum Champ
Total posts: 796
posted November 02, 2005 03:52 PM  
"the less the car rolls, the worse the sidebite is" Thats the key right there.

Is the spring / slider mounted on the swing arm itself? Or is it attached to the bird cage?

If its mounted on the swing arm, which is what i run. I would say you need a short bar, it will create more side bite, instantly. Put it on with 4" of rake, up to the chassis side, start at the same height that the J-bar is now, on the pinion side.

Sounds like your going in to the corner on the LR bars, if you are, all that J-bar angle will make you loose in the middle. Alot of angle in the J-bar promotes left side lift, not true body roll.

If you need more true body roll, lower the short bar at both ends equally, just move the whole thing down towards the ground.

As well, sometimes coming out you need the LR to get up on the bars faster, thats where the angle comes into play.

Short bar all the way, and dont be afraid to make it short, like 10" or so. Sounds like the car is to slow for you, and your always waiting for it.


dogwalker
Dirt Full Roller

Total posts: 65
posted November 03, 2005 09:41 AM  
usar??? I thought you were running UMP with 2 1/4" of stagger.... Get rid of the stagger and you should be able to get in the gas through and off the corner. Hoosiers work with stagger on dry, but A/R's do not. Stagger is great for tacky, but it's insanity on dry. If you rr is compressing 4", then I don't think it's a "getting on the rr" thing.

Kromulous
Dirt Forum Champ
Total posts: 796
posted November 03, 2005 10:36 AM  
Them American Racer tires must be a real treat to work with. Sounds totally different than a UMP Hoosier.

Krom.

dogwalker
Dirt Full Roller

Total posts: 65
posted November 03, 2005 02:14 PM  
Actually I might have overstated the stagger case somewhat. It's not quite insanity on a 4-bar car as much as a 2-link. A few years ago I was running a 2-link swing arm car and was running low on tires and had to run a really dry main with 1 1/2" of stagger and it made the car undriveable (for competitive purposes). The next week I swaped them back out for a set with about 1/4" and it was back.

The 4/z car I've had for the last couple years is not nearly as sensitive to stagger because the rear end moves around so much anyway, but usually the McCrearys are within 1/4" if you don't mess with em. Getting over 2" of stagger in a AR G60 usually requires a fair amount of pressure while being left out in the sun.

To me, it sounds like a lot of the side bite problem is throttle sensitive, like the rear is very loose under acceleration. For an AR, it's a bunch and I think even on a 4/z it would contribute to the car being loose through and off the corners when trying to get back into the gas.

It could very well be the roll center like you stated and just needs the j bar moved, but the stagger caught my eye when I noticed the usar part.

DirtTrackRacingRules 3 8
Dirt Maniac

Total posts: 101
posted November 03, 2005 06:05 PM  
i dont think i mentioned that i am running on American Racers G60's, dont know if that matters. we can use the BTC tires as well thats why i can get the stagger so easy, i have had as much as 4" of stagger and won on it earlier in the year(tracks still had some moisture in them)

less stagger than what i run makes the car way to tight getting in the corner.

my rr spring is on the swing-arm, and its a 16 inch swing-arm(FYI) dont know if it makes a difference.

I have been thinking about putting a shorty bar on it for a while but before last saturday my race before that i won the car didnt really have the side bite but i was on a cushion, and i didnt change it for this one,wish i would have

thanks again for the help you guys are awsome!

[This message has been edited by DirtTrackRacingRules 3 8 (edited November 03, 2005).]

DirtTrackRacingRules 3 8
Dirt Maniac

Total posts: 101
posted November 03, 2005 07:30 PM  
when using the shorty bar, where do you mount it on the pinion??? in front or behind and what would the differences be???

Kromulous
Dirt Forum Champ
Total posts: 796
posted November 04, 2005 05:49 AM  
In front or behind, of the pinion plate?

Mine is in front, it will mount just like the J-bar, same side of the Diff housing just on the other side of the pinion than the J-bar, J-bar mounts on right side of the pinion, short bar on the left side, the LR tire side.

I don't have a pic, or would post it. Maybe somebody can post one for ya, of a short bar mounted up properly.

Two things the short bar gave us when i put it on, and i was also very reluctant, bad move on my end. Anyway it gives you loads of bite to play with, side and FWD bite. As well it makes the car quicker and more apt to change direction, quicker. Alot better response out of the car. My driver commented that it felt more like a real race car the first time out with it, car was racey and responsive.

The RR swing arm makes the car alittle on the cadilacy side anyway, smooth and kinda dull. So the short bar helped it.

They can be rough on a rough track, but i havnt seen it pogo stick as some guys say. When a track is super rough, i'll just slap the J-bar back on and run it.

DirtTrackRacingRules 3 8
Dirt Maniac

Total posts: 101
posted November 06, 2005 06:51 PM  
what would putting the rr spring on top of the rear end do???

Vorby 78
Dirt Roller

Total posts: 6
posted November 09, 2005 08:51 AM  
guys, I would like to see how a short bar should be mounted also

Kromulous
Dirt Forum Champ
Total posts: 796
posted November 09, 2005 10:12 AM  
I'll try and take some pics this week sometime and post them or email them to ya.


Krom.

DirtTrackRacingRules 3 8
Dirt Maniac

Total posts: 101
posted November 10, 2005 04:51 PM  
I have also heard that putting the 4bar on the right you will gain side bite, is this true?

20crew
Dirt Roller

Total posts: 18
posted November 10, 2005 07:26 PM  
Depends on who you ask ,some say just the opposite . WE changed our car to a 4bar rr really [was 4bar lr Zlink rr] Didn't notice much if any change in side bite . it did really free the car up getting in.

DirtTrackRacingRules 3 8
Dirt Maniac

Total posts: 101
posted November 11, 2005 06:09 AM  
has anyone went to 4bar rr that had the swing-arm on before? If so did it help side bite?

DirtTrackRacingRules 3 8
Dirt Maniac

Total posts: 101
posted November 13, 2005 05:12 PM  
Hey DOGWALKER when you were talking about the z-link bar having angle did you mean the back bar or the swing-arm? Which bar is making the car get up on it? What should i run my swing-arm angle at if i run the back bar level or even past zero, putting it down hill to the front of car rather than up hill like it is now?

dogwalker
Dirt Full Roller

Total posts: 65
posted November 14, 2005 08:02 AM  
I leave the swing arm slightly uphill (one hole from bottom). If it's super slick, I'll move it down one more to the bottom (flat).
When it's tacky, I put the back bar all the way down to add rr bite to keep the car loose, them move it back to level as it dries out. Usually the rear bar change is more noticeable than the swing arm angle change. Someone else may know better, but it seems like the swing arm angle causes the car to "get on the bars" more than the rear. What's been your experience with which bar has the most effect on getting the car on the bars Krom? ....i've always tried to keep the rr real calm.


Kromulous
Dirt Forum Champ
Total posts: 796
posted November 14, 2005 10:45 AM  
Your on the right track, i run 10 degrees up angle in the swing arm, as a base set. Thats 10* from hiem to hiem angle, not on tube, measuring wise.

The rear bar will help fine tune the adjustments, but the swing arm has the most influence. More angle, up angle, the more drive in the RR.

The rear bar will help the car generate more rear steer, quicker or slower. More down angle, the more rear steer. Plus it influences drive.

Krom.

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