Birdcage bar positions

[hunterracing]

What would affects be if you took little angle outa top bar but then lowered it equally down on cage and frame to lowest hole on cage then took the lrl and lowered it to 5.5 on cage and lowest hole on frame keeping same angle would this give more drive and maybe take some steer out as well?

[Kromulous]

Speaking on the LR? you asked this before and i can relay a few findings. Now a disclaimer, this is on a Mod, but i found it about the same.

The RR i raised the top bar to 5" and the lower at standard 4.5", the car laid over bad on the RR. Same bar angles, i set it back to 4.5" on the upper bar and the attitude was better. May be a great adjustment when its super slow and slick.

LR, lower bar to 5.5" on a zero index deal, actually it indexes a little so... Anyway, same angles on the bar, just lowered it on both ends. It makes a lot of drive, and really promotes the hike. We're running around 300lbs of droop load.

Once i moved the LR bar, car really made the drive we needed. I would be careful on a SLM, track would have to be somewhat slicked off or you might just shove the nose all over the track. This has been one of the biggest impacts to the car, really changed how the car drove.

Also one of the biggest changes i have seen is a 3" bar length split on the RR, really deadens the drive and makes it lay over and calm. The indexing change really helped.

Hope the helps. We race on dry slick pretty much all the time, Hot Laps you get some wet but thats about it.

Also this was all with the same springs, shocks and stagger.

[hunterracing]

That makes sense

[pa_dirt]

Speaking on the LR? you asked this before and i can relay a few findings. Now a disclaimer, this is on a Mod, but i found it about the same.

The RR i raised the top bar to 5" and the lower at standard 4.5", the car laid over bad on the RR. Same bar angles, i set it back to 4.5" on the upper bar and the attitude was better. May be a great adjustment when its super slow and slick.

LR, lower bar to 5.5" on a zero index deal, actually it indexes a little so... Anyway, same angles on the bar, just lowered it on both ends. It makes a lot of drive, and really promotes the hike. We're running around 300lbs of droop load.

Once i moved the LR bar, car really made the drive we needed. I would be careful on a SLM, track would have to be somewhat slicked off or you might just shove the nose all over the track. This has been one of the biggest impacts to the car, really changed how the car drove.

Also one of the biggest changes i have seen is a 3" bar length split on the RR, really deadens the drive and makes it lay over and calm. The indexing change really helped.

Hope the helps. We race on dry slick pretty much all the time, Hot Laps you get some wet but thats about it.

Also this was all with the same springs, shocks and stagger.

What do you mean by the 3” rod split? We are struggling with forward bite as well.

[Kromulous]

Bar lengths, lower is 15" and upper is 18". That is on the RR.

On my car, LR, with the zero index deal, i have to run a 18" upper, and a 14 3/4" lower, and it has welded in plates (SMH) Does anyone think there is more traction to be had with a shorter upper bar? Thinking about making a shortening bracket like what Rocket used to have on there cars and going to like a 16 1/2 or so.

[hunterracing]

That’s a big split on lr would think it would rollsteer a bunch

[Jking24]

15 and 18 is pretty standard in the right side. I think some of the older mb stuff would run somthing like a 13-14" lower at times iirc

[brett4]

Kromulous, what LR spring are you running with 300lbs of droop load?? what kind of lower bar angle are you running on lower left when the car is on the ground??? is this a UMP mod

[Kromulous]

I run a 100lb spring, i like to be able to measure it on the fly so the 100 is easy to add up LOL. Some run the 80, i dont think there is any difference. On the Mod with the slider its a pain to pull it off and smash it, so i just measure the compressed spring and multiply it to the spring rate.

So at full droop my spring measures 17" on a 20" spring, is it exactly 300? probably not, but its close.

Lower bar is 10 degrees, or so. I will have to measure it on the ground, that is a estimate.

Yes, UMP Mod, so your mileage might very with a SLM, but i was trying to relay some info to Hunter racing, he and i asked before about the bar position on the cage, and not a lot of intel was out there on it.

[Jking24]

I run a 100lb spring, i like to be able to measure it on the fly so the 100 is easy to add up LOL. Some run the 80, i dont think there is any difference. On the Mod with the slider its a pain to pull it off and smash it, so i just measure the compressed spring and multiply it to the spring rate. So at full droop my spring measures 17" on a 20" spring, is it exactly 300? probably not, but its close. Lower bar is 10 degrees, or so. I will have to measure it on the ground, that is a estimate. Yes, UMP Mod, so your mileage might very with a SLM, but i was trying to relay some info to Hunter racing, he and i asked before about the bar position on the cage, and not a lot of intel was out there on it.Just a little fruit for thought always wanna measure the free standing height of the spring off the car. Most manufactures are pretty good about this now days but not so long ago I've seen free standing heights vary over+- 3/8". secondly the first inch is usually soft so maybe 90# on a 100# but then you couple that with the variance in height you could be off nearly 40# either way. So it is entirely possible that your 300# could be 340 or 250. I'm not insinuating you don't already know this krom just thought it was info worth mentioning

[Kromulous]

Ive seen some really collapse, but i run Eibach pretty exclusively, and not seen them move much. Usually i will throw them on the smasher a couple times thru the year and check too.

Next year i am going to put jack bolt on the LR upper shock mount, so i can unwind it, should make it a lot easier to get on and off the car. That or get one of them Advance Preloader deals, them look pretty sweet.

[Jking24]

Eibach springs are super consistent a freind of mine mic'd them and across like six or seven springs they were within. .012" and they come preset so that shouldn't change unless the sorting incurs damage

[JustAddDirt]

Ive seen some really collapse, but i run Eibach pretty exclusively, and not seen them move much. Usually i will throw them on the smasher a couple times thru the year and check too.

Next year i am going to put jack bolt on the LR upper shock mount, so i can unwind it, should make it a lot easier to get on and off the car. That or get one of them Advance Preloader deals, them look pretty sweet.

Do that with the LR shock, and the eliminator mount.
That way you don't have to have shock extensions if a quick shock change is needed. Or you switch brands, lengths vary.

[Kromulous]

JAD, were you on a shock in the front, slider in back, or coil over on the LR? We tried a coil over and just cant keep the car up.

This car is weird, its has the front shock on a jack bolt deal, and the back hard mounted. I guess they dont want you messing with the spring base, but seriously. That and welded in 4 bar plates, and these front shock mounts are sad.

Im gonna retire someday, and build my own cars, my way LOL. Come on lotto !

[MachineMasters]

JAD, were you on a shock in the front, slider in back, or coil over on the LR? We tried a coil over and just cant keep the car up.


I'd bump your LR coilover compression valving up so it has 300lbs of compression at 2" per second. Keeps LR up and lets you drive like you had a shock in front.

[Kromulous]

Ok, wow thats some compression, i'll check the dyno numbers on what we got now and see if i am close. I cant remember.

Right now i am working on making the top bar shorter, its on a zero index deal and the top bar is 18.5" long, i want to get that down to 17" at least while on the zero index. I am hoping to get the car to traction up faster, more would be good, but i really want a faster reaction.

[MachineMasters]

Ok, wow thats some compression, i'll check the dyno numbers on what we got now and see if i am close. I cant remember.

Right now i am working on making the top bar shorter, its on a zero index deal and the top bar is 18.5" long, i want to get that down to 17" at least while on the zero index. I am hoping to get the car to traction up faster, more would be good, but i really want a faster reaction.

Valving like that would only be suggested as LR coilover behind with no shock in front. It's a lot of shock but if on a soft spring with nothing in front it doesn't feel that stiff.

Quicker traction on the LR - i feel like this is related to LR static bar angle, with more angle making things happen quicker. Also feel like the 5th coil position (front to back) has an effect with quicker happenings as you move it back. Might not be "correct" but what I've felt.

[billetbirdcage]

You need to keep something in mind when dealing with Shock numbers especially LR:

While most cars the axle may travel at a certain speed on average, the actual shock speed can be dramatically different depending on what the cage is doing. Meaning if the cage is actually indexing a lot or very little. This goes back to terminology (the whole no index term), a true no index is not the same as the referred no index (actually more like "no over center")

Say the axle moves 4" on the LR and it's traveling at 4" per second: Now with a normal cage set up (cage actually rotates or indexes) then the LR behind shock is not traveling at 4" per second until it gets close to ride height but when it first starts to drop it can almost move none (could be close to 0" per second) or semi close to that 3-4" range once the car sets down closer to ride height. Where on a true no index (cage does not rotate) then it will move at roughly 4" thru it's entire travel.

So that can be a huge difference in how stiff the shock acts on different LR cage set ups.

[Kromulous]

What's you guys opinion on a car that needs 350 to 400lbs droop load to make any traction?

I keep thinking something is off elsewhere, design or ?? This is the reason i want to shorten the top LR rod to see if it will help, and i can decrease the load. It messes with my deck height having so much load, but it is what it is i guess.

On my set up, i am traveling the spring 4 3/4" from ride to full droop. I am going to check how much angular rotation i get in that movement on the Birdcage.

[cjsracing]

What's you guys opinion on a car that needs 350 to 400lbs droop load to make any traction?

I keep thinking something is off elsewhere, design or ?? This is the reason i want to shorten the top LR rod to see if it will help, and i can decrease the load. It messes with my deck height having so much load, but it is what it is i guess.

On my set up, i am traveling the spring 4 3/4" from ride to full droop. I am going to check how much angular rotation i get in that movement on the Birdcage.


That seems like a lot. I start at 200ish and I have throttle push with that in qualifying.

[MachineMasters]

That seems like a lot. I start at 200ish and I have throttle push with that in qualifying.

Agreed.. i've never been over 185, usually 100-150.

maybe the RR is too stiff and it takes a lot of LR to make it feel tight enough