LR Chain / Limiter?

[Kromulous]

I was watching a video on you-tube of a Mod, Shaw car, with a LR limiting chain. Interesting part to me was, you can see the chain get tight, and go basically solid, but you can see the LR tire get more load on it, it really gets compressed.

That got me to thinking, dangerous i know, but... if the rear end / tires are driving FWD and the LR bars are in extreme upward angle (full hike), driving the chassis up and on to the RF hopefully. Then you engage the chain, question is to me wouldn't it pull down on the chassis at the LR corner?

I had always though about this in reverse, if it hits the chain you loose all drive, but after watching that video i am reviewing that, not sure thats correct.

[MasterSbilt_Racer]

I was watching a video on you-tube of a Mod, Shaw car, with a LR limiting chain. Interesting part to me was, you can see the chain get tight, and go basically solid, but you can see the LR tire get more load on it, it really gets compressed.

That got me to thinking, dangerous i know, but... if the rear end / tires are driving FWD and the LR bars are in extreme upward angle (full hike), driving the chassis up and on to the RF hopefully. Then you engage the chain, question is to me wouldn't it pull down on the chassis at the LR corner?

I had always though about this in reverse, if it hits the chain you loose all drive, but after watching that video i am reviewing that, not sure thats correct.

If the chain is tight, from the axle perspective, an upward force is applied. From the chassis perspective, a downward force is applied.

[Matt49]

I think that once you are fully hiked (chain tight) you are getting far more forward bite from the raised CoG than from anti-squat. But I could be crazy.

[MasterSbilt_Racer]

I think that once you are fully hiked (chain tight) you are getting far more forward bite from the raised CoG than from anti-squat. But I could be crazy.

I agree. Once you have reached near steady state (not accelerating hard) the bars shouldn't have much load from pushing the chassis.

[Kromulous]

So in turn, begs another question.

Lift-bar, wouldn't it be wiser to run the 5th coil closer to the reared to keep said anti squat longer, or all the way around the track? If the lever arm is to long, it cant lift, and begins to come down sooner.

Looking at it this way, one could plot out a correlation between the 5th coil pivot point, and an inline distance from the LR to RF points of tire contact, moving that point would be key to keeping an applied load on a corner. make any sense?

Also, concerning the steady state, the chain only slacked when he left off the throttle. I know there will be less force on the bars in the later part of the straights, but its apparently still there to some degree. Would love to be able to measure it.

[7uptruckracer]

We have found that with the 5th to far back it causes too much pinion wrap on accel and decel and has adverse effects. Most don't run it far back anymore, I know one that does but he is on a reverse Dual Stage Setup....I just RONCO it. Set it and Forget it

[Matt49]

I've seen benefits to forward bite in moving the 5th coil back but there is definitely a tipping point. Like 7up said, it allows for too much axle wrap up. The pinion mount for the j-bar is about 9 inches ahead of the center line of the axle. So if you get 4" of movement from your 5th coil at 31" out, that's over a full inch of upward movement of the j-bar pinion mount. This leads to what I can only describe as "instability" coming off the corner.

[7uptruckracer]

We actually had it all the way back earlier this year on a Super, and it messed up entry from excessive wrap up and wrap down. I also had a very very good touring crew chief tell me to set it at X length, put a 200# spring in it and stuff spring rubbers in it till you like what you get. We have done this on the LR of asphalt mods as opposed to upping the spring. It has a different effect you are changing the springs compression characteristics but their is a difference in the springs rebound characteristics say from a 150 coil spring with rubbers to a 250 with no rubbers.

[Kromulous]

I ca see that, it would have to be wildly progressive with the rubbers.

I've always thought we left alot on the table concerning the 5th coil, i am going to work with it alot this year i think. Shock valving on the 5th coil to, i believe it should be a Linear valve and next to small amount of bleed off.

All of that pinion wrap would affect your roll center as well? with the pinion mount moving around so much. I am going to move it back 1" at a time and see if i can find that tipping point, or at least what it does good or bad.