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Author Topic:   Loose or tight?
leapinlizard
Dirt Freak

Total posts: 402
posted November 03, 2005 09:17 AM  
Car enters really good. When I pick up the throttle as early as I'd like the car will come up in the "bars" and push. Push bad. Not as bad with a 3 off rather than a 4 off. If I pick it up slowly it's better in the center but it'll get loose on exit and the lap times are fall off. If I pick it up quickly but roll out slightly to keep the car from getting way loose in the center it will snap tight as the chassis unloads thru the center. Then the corner speed ***** and it get's loose on exit trying to catch up. IF... I can find the very fine line between getting back in the gas to early or too late the car is good everywhere. But man that line is thin. Moving up the track helps the center loose but I have nowhere to push to on the throttle. Running a lane down the hill helps but the laps speeds are slower. What can I do? Should I stay in the throttle thru the center to keep the suspension loaded and fix the tight on the throttle? How?

3 link with LR in front, RR behind, Striaght panhard bar mounted behind rear. 16" long.

Kromulous
Dirt Forum Champ
Total posts: 796
posted November 03, 2005 09:30 AM  
3 & 4" offset on the RR?

If so, the 3" is loosening you up in, and tightening off.

Thats the key i believe to your problem. Could you stand the car a little free-er going in?

All that drive out is good, but you need to free it up in so you can let it come around a little more, hang the rear out a little more. That way when you pick up the throttle the car is turned enough to make it out.

That or you increase the RR drive, maybe more bar angle, or decrease LR drive, more stagger or less bar angle.

You may try moving the pull bar an 1" or 2 over to the right, that may help depending on how bad the push is.

Just some thoughts.

Krom.

dogwalker
Dirt Full Roller

Total posts: 65
posted November 03, 2005 09:49 AM  
If it's clamped on LR, you may try it floated to reduce the initial dynamic cross.

leapinlizard
Dirt Freak

Total posts: 402
posted November 03, 2005 12:20 PM  
3" on RR.

I tried a 4" off in the slick. The car pushed so bad it was undrivable. Kept haveing to set the car twice. One to get in, and once to correct the tight on the throttle. I am building a bigger engine next year. Will I be able to power through the throttle push and loosen the car up in the center? Or does that make it worse? The offset are

LF RF
2 3

LR RR
3,4 3

[This message has been edited by leapinlizard (edited November 03, 2005).]

autoshop
Dirt Freak

Total posts: 298
posted November 03, 2005 12:50 PM  
rr spring in rear will always be tight under throtlle simply moving the spring to in front or on top will make it more nuetral feel. I would run the springs both in the rear only when the track is dry.

Kromulous
Dirt Forum Champ
Total posts: 796
posted November 03, 2005 01:04 PM  
Extreme12x is the best at this 3 link stuff, maybe he will post up some thoughts.

A couple things i would try.

Raise the panhard bar up on the frame side 1", more left side lift will generate more rear steer. Use this if you going in up or just coming off the bars. If your going in flat, this wont help i believe.

Put a 4 on the LR, and 3 on the RR. Try to add about an 1" more rear stagger. And see if it gets a little better. Make sure your LR bite is the same with the smaller tire.

Then add some front stagger, front stagger is a quick way to increase LR bite. I'll do this sometimes just to see if i need more in the car. Then fix it right at home on the scales. This will loosen in, or off throttle.

You gotta 2" on the LF now, so it sounds like your reaching for some more LR bite anyway.

Then i would try more RR bar angle, to increase RR drive so the car can power thru this push. Thats where your big motor will help.

Krom.


leapinlizard
Dirt Freak

Total posts: 402
posted November 03, 2005 02:02 PM  
Other thought's:

I have added stagger to loosen the center but I didn't like that. It didn't help our tight entry.

Our engine last year was a worn out back up. 9:1 with dart heads and solid cam. That's it. We were at least 150 hp shy. But he track is alway's super dry half way though the heats.

Since our track is really tacky high banked 1/2 mile paper clip shaped with long corner's the car works with a 3" off on the LR on the heat with LR spring behind. We were running a 3" off on the LF but that gives us 20# of bite if nothing else changes. We didn't know what we were doing yet either. The car is a little loose there. The original builder said the car was always loose for him. But he likes it that way. I am too new to know what I like most. I know I don't like it tight on the throttle. He didn't know why though. He's the type to wrench till it flies without regard. We put a 2" off on the LF to get some bite before we understood and the car was better on entry so we left it. Then we moved the LR spring in front from behind to loosen entry more and that helped but the side affect is to tight on the throttle. If I put the 3 off back on the LF will that keep the entry the same but not jack in so much bite on the throttle?

I want to keep the entry but ged rid of the throttle push. But not so far to loosen entry.

Is that asking to much? lol

PEwaste
Dirt Roller

Total posts: 14
posted November 03, 2005 02:11 PM  
This is Xtreme12x... and for some reason I can't log in under Xtreme12x. Must have something to do with the whole schpeel with 66jj, or his other usernames.

Anyways.. Back to what's important.


Ok, lets break this up into 3 parts of the corner...

Entry

You are getting in real good... Now are you driving the car in or floating? Driving the car in will be driving it straight and easing off the throttle, floating will be easing out of the gas and letting the car begin to turn rather than pointing and going

Middle
Now when you pick up the throttle, it is beginning to push... If you are easy on the gas it isn't as bad right?

With the picking it up quickly and then rolling out of the gas to keep the car underneath you, that is basically breaking the tires loose to snap the back end around.. and then you have to pedal the car to keep going

Exit
It is coming off loose because of the early tight, no matter what you do.


Here are some quick things to try at the track:

To fix the center, up the Panhard on the pinion one hole (Without knowing exactly where you have it mounted and the angles I can't go much further with that)

Put a 25 pound softer spring in the RR. This will Tighten the entry, and help from the center off.

I'd go with the RR on top anyways, and run the same percents that you are running now


Some other idea's:

Raise the RR trailing arm up a hole to increase RR Drive
Soften up that pull bar, what rate is in the car now? (on a 2 link car with limited power, I beleive in a soft pull bar spring to help "lift" the chassis on the bars


Here are some questions that I have that will help me help you a little more

What front springs are in the car, what bar angles, lengths, pull bar spring, and shocks.
What percents are you r unning also.

You don't seem like you are far off. This is a symptom my car had at the start of the year, and I ended up finishing 10th with the car handling like this, and made 2 changes, moved the panhard up a hole on the pinion and raised the RR Trailing arm up a hole and was the fastest car on the track and a consistent top 5 after that. The key is keeping the front end happy, the back end gets you off, front end gets you in.

If anyone needs ANY help, e-mail me at xtreme12x@mchsi.com or catch me on MSN Messenger at Jet_96_2@hotmail.com and I will help you in any way that I can.


leapinlizard
Dirt Freak

Total posts: 402
posted November 03, 2005 03:26 PM  
I really appreciate the feedback. This is helping alot. You must be god like or something to know exactly what my car is doing by my not so educated guessing.

I've been "floating the car in" I roll out easy and turn left slighlty to get the car to roll over to the right and the left rear start's pulling the rear around. Then I "catch" the car sliding and use the throttle to get it going forward while I keep the front wheel's pointed in the direction I want to go in. If everything works, the car goes forward while back end rear steers thru the center and off the corner.

If the car has too much forward bite then you get push right? Or also stated as "not enough side bite".

So I have to either change my timing to pick up the throttle. (I don't like to change my routine unless it's imparitive to be faster after the car is already on the track)or add RR bite till it's good.

I tried really throwing the car in hard by driving deep and snapping the rear around with the brake but it's tricky at best to recover the very loose center. AND not good in traffic at all. I like the smoooth style better. I'll try leaving the front alone and adding right RR drive via the lower bar.

The rest of the setup for FYI.

LF #650
RF #750
LR #175, 5 degree's up, 20" long
RR #225, Level, 20" long
Pull bar, #1100, 3" of movement.
Percent's are:
Left Side%, 53%
Rear% 55%
LR bite 40-60 Lbs. I've managed a two top fives and 2 top 15 of 25 starters in the features with the current setup.


x13jc
Dirt Freak

Total posts: 390
posted November 03, 2005 03:44 PM  
Your Level RR bar is the culprit. It needs a little angle in it, increase drive and viola, your dialed in.

It may loosen entry, if it does drop down on the LR bite.

As well, this winter you should consider making a plug for the LR and running a shorter link on that side. Maybe a 15" or so. If your rules allow it.

Extrme12x can guide you on a good length for it. Plus confirm the above, but i believe that RR bar is the problem.

Krom.

washeduptoo
Dirt Maniac

Total posts: 155
posted November 03, 2005 04:48 PM  
When we used to run a 3link, our lr spring was always heavier than rr unless we were running a swing arm. On a 3-link,does the spring in front lessen the spring rate like on a 4-link? How about the spring behind, does it increase the spring rate? Just wondering for future reference.

PEwaste
Dirt Roller

Total posts: 14
posted November 03, 2005 07:37 PM  
This is Xtreme12x again

Here are some idea's

Put your 175 on the RR and 225 on the lr (But I think you've got them swapped around and you have it right on the car)

For now, put some angle in that RR bar, and also in the LR bar. Try running both bars at about 15 Degree's up. With a 20" Bar, you'll need more angle than you have.

Also, try about 100 Pounds of Left rear,
Take that pull bar spring and toss a 800 or 900 in there. We see upwards of 4 inches when the car is working good (Just make sure nothing overextends and driveshaft clearance is ok)

Also, put about 57 percent rear in the car also

Over the winter, build a plug for both sides, run the left rear at 14" heim to heim, and RR at the same length. Put your RR on top, put a 250 in front and a 175 on top and let her dig. Try the same angles, 15 degree's left and start with 15 on the right. Keep your percents the same also.

This should help the car all around the track.

racer2
Dirt Freak

Total posts: 352
posted November 04, 2005 05:48 AM  
the thing that helped me out the most on my dw8 3 link was putting a short bar on the left with about 30 deg of angle, just took off the long panhard bar behind rear end and put a j bar on it.gonna try this .

[This message has been edited by racer2 (edited November 04, 2005).]

leapinlizard
Dirt Freak

Total posts: 402
posted November 04, 2005 06:53 AM  
You right, I told you wrong. I have it on the car the way you say.

I've written everything down in my log book. I'm armed with a ton of things to try. My track has three play dates before the season start's. So that gives me three chances to screw something up and not suffer. lol


I didn't change the LR spring when I moved it in front. Just reset the desired precent's. Moving the spring closer to the pivot point should demand a increase in spring rate correct. Are we just splitting hairs here?

x13jc
Dirt Freak

Total posts: 390
posted November 04, 2005 07:42 PM  
pewaste, i fabricated my own bracket for the left rear earlier this year, before going to swing arm. if i could get that bracket reinforced better, to where it would not bend from the pressure, I would put it back on, and drop the swing arm. incredible bite. will tell ya later what i found. i made another one but unfortunately, the first one broke. need better reinforcement.

X

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