3 link rear springs. how soft is to soft?

[dirtracer07x]

Ok guys warmer weather is coming and our track is already getting dry slick. i am new to this bmod 3 link stuff and am wondering if soft springs would help drive off the corner. in all other forms of racing you want the rear to squat off the corner. why in dirt do we want the cars to hike up? 08 hoffman on big 3/8's with good banking 600lf, 550rf, 200lr in frt, 175 rr on top, soild pull bar 18 deg, 1/4 lr lead, lr bar 20 deg up, rr 5 deg up, left 52%, rear 56%, cross 51%, bite 75. car is free in (off the gas) little loose in middle, but not much drive off. could you drop rear springs to 175lr and 125 rr and get more drive off? still learning......

[Confused?]

Hiking up is what creates the drive you are searching for. It creates a form of mechanical traction. For the car to raise up, it has to push against something. That something is the track surface.

As far as your car goes, softer springs don't usually create more drive. They help the car turn better allowing you keep your momentum up through th the corners. I would swap the front springs and work on keeping in the tthottle some through the corner. The more throttle on entry, the tighter the car will be. Focus on learning that and trail braking on exit before you make a bunch of changes to your car. On a 3/8 mile, you shouldn't have to get completely out of the throttle unless it is a stop and go track or something happens in front of you.

[RaceMentally]

I'd switch the rears. I like a light LR faster indexing so I'm not relying on upper bar angle. Keeps weight on RF easier as well as up on bars. Comfortable for myself.

[Confused?]

No indexing. It's a three link car, not a four bar car.

[bob75]

If your lr has 20 degrees at full drop not enough

[RaceMentally]

No indexing. It's a three link car, not a four bar car.Whoops. Still doesn't matter run a lighter spring. You're trying to achieve the same thing but with a different suspension system.

[Confused?]

Going to a 125 on the RR will usually make a car very loose on entry when off the gas. Whatever you do to increase bite generally has the opposite effect on entry when you are off the throttle. That's another reason to learn to stay in the throttle some through the entire corner.

Your spring choice can also be affected by what tire you run

[a25rjr]

I always had to run 125-175 lbs of bite during the summer months. However, that will make your entry looser. Usually, I would roll the lr back 3/8 inch, stiffen lf spring, and increase rake in jbar.

[Matt49]

Here us some good reading on anti-squat and it is focused on the 3-link design. They working with asphalt late models but the same principals apply to dirt with the possible exception of what you're using for lateral location (panhard bar) and where that is mounted. But that doesn't really affect anti-squat.
http://www.hotrod.com/how-to/chassis-suspension/ctrp-0406-antisquat-explained/

[a25rjr]

Good article from Mr. Bolles. I don't think he gets near the respect he should from the dirt world. I have found his software to be very helpful, esp the roll angle one. I hope he will update it one day, as it has a few minor kinks.

[TS3g]

Your setup looks pretty close to what I used to run on my b-mod. In your case, I'd soften the LR spring like was mentioned, as should help it get on the bars easier and tighten entry a little (if the car comes off the bar completely).

I also ran about 130lb or LR bite in my car, which unfortunately would loosen your entry off throttle. To tighten entry back up, you could keep stiffening the LF spring and or lower your panhard bar.

Also, what shocks are you running?

[dirtracer07x]

never thought about running a lighter lr spring. might try that. im ok with loose in if helps me coming out. Running integra dry slick shocks. rf hold down, lr hold up. i am a heavy guy...260 and im pretty sure my lr bite goes way up with me in the car. that is why i didnt think about a lighter lr spring. also thought about putting more caster split in it as this should help load the lr at mid corner counter steer also which would help speed off. think i will start with squaring the rearend... no lead... and switch the frt springs

[powerslide]

think i will start with squaring the rearend... no lead... and switch the frt springs
As I read through this thread I was thinking these exact same things.

Get in the car and see how much LS%, Rear%, and LR you have w/ you in it.
If still loose on entry after trying what I quoted try lowering the RR bar to 0. How much stagger?

[langdonracing48]

Try a heavier RR spring, like a 200. I didn't like soft springs on my 3 bar stuff in the slick, especially the LR. I always ran 200 RR, and 225 LR with 95# bite, with a 12" panhard bar set at 3" of rake. LR trailing arm at 18-22* depending on the track, RR 0-5* up hill, almost always at zero. Pull bar 20* down hill. 2" offset wheels on front and LR, 4" on RR. Always keep my cross between 48-52, left side weight 55%, rear weight 55-57% full of fuel with me in the car(I'm also 260lbs).

[langdonracing48]

I run my caster at 5* RF, 3* lf, camber at 5* RF, currently 6* lf. Always use to run 2-3 on lf, but seen some newer cars up here running way more than that so I decided to try it. I love it so far.

[mod88s]

I would go to a 225 on LR since the spring is in front of the rearend. Also bump up Left side just a smidge. try 52.4 Swap front springs. Go 1 hole down on both bars. go up on rear 2% more, 150lbs bite

[dirtracer07x]

Update: last wednesday night we went back through the car and found i had 5/8" LR lead. I dont know how we did that but at least we found it. Also lr bar was only at 15* and rr at 0*. so we set rearend straight up and moved lr bar to 20* and rr to 7*. Car was great until i got hit when another car spun and I checked up. After that it was a 3 wheeled monster. Came in and figured out the lr shock mount broke which was also my travel limiter. So this week I will add a chain and a 3 off rf and leave everything else the same and see how it goes. Also to note: I run rr spring ontop of rearend and lr spring on slide in front if this matters. Question: when checking bar angles and rear end square is this done with or without driver in car?

[langdonracing48]

Without driver

[JustAddDirt]

i would say with driver, because the driver is in it when it is on the racetrack...right?

[dirtracer07x]

question? can i move the lr slider/spring behind the rearend and move the shock to the front? what advantage and disadvantage? the reason i ask is after i broke the shock mount last week the car really got up on the bars and turned great and had forward bite. The shock was limiting the travel. if i move it to the front i should get more travel.

[mod88s]

You dont want to move the spring to the back on a 3 link. On the throttle, the rear end wraps up into the spring when its in the front. This is what helps to load the LR. Putting the shock on the front wont give you any more drop. Just put an extension on the end of the shock.

[TS3g]

^^^ Agreed

Are you allowed to put a chain on the axle tube for a limiter? That would be best case scenario

[langdonracing48]

When the car is at ride height, make sure you only have about 3" of shock shaft showing on LR. Use extensions if necessary. That'll allow for plenty of travel.