Left rear in front

[hpmaster]

Ok so what about a 4 link like this?

We ran both bottom bars down on the chassis about 5-degrees uppers 25+ left and right 18+, thats what we ran back in the day. As I think about it might have been a 225 spring on the right rear. Trycycling, hardly see over the hood but a ton of drive, if you didn't drive the he!! out of it, tail out it, rf brake off pushed like a dump truck, but a fast dump truck..

[fastford]

185lb spring clamped up on the LR in front, 90/10 on top of rear end, 275lb on RR in front, , 21" to 23" j bar, 40" lift bar 350lb spring on a dummy shock, chained limiter no 6th coil 550lb springs across the front turn off RF brake give it a bunch of rear % and go!

we won a fair amount of races back in 1999 - 2001 on that same basic set up , I think I wound up on a 400 rf though.

[V1SLM]

Almost the same set up as hpmaster...we ran LF 550, RF 500, LR 275 on clamp in front, RR 225 springs. Left side was 55%, rear was 54%, ran around 200lbs of bite, ran a 400lb 5th arm. Our left front was useless....

[Bcollins82]

I believe you guys are overthinking this a bit... I think the 5 link dual birdcage idea is kinda cool, but I don't think its really necessary. Look at how the rear mount reacts on the birdcage right now. It doesn't actually "push" the spring into the chassis, it just slows the rate that the LR spring is unloaded when the LR drops. By slowing down that motion it effectively softens your wheel rate on the LR. I would put the spring in front with an extra soft spring, or preferably a stack setup if the clamp bracket wasn't allowed. If the clamp is allowed, there's no reason to step back 15 years on your setup. Run a shock on the birdcage to control the LR timing, and put the spring on a clamp bracket. Cars now travel nearly as much on LR as they did back when people ran clamped up cars, but they don't have the attitude of the car above because of the more balanced package being run now with the cars being down on the RF, not rocked back on the RR.

[Dirtmod13]

Clamped up?

Anyone got a pic of the clamp bracket? Rule states single coil over mounted to birdcage. So is the clamp on the tube or the birdcage?

[Dirtmod13]

Also, who are the off the wall crazy guys that have the real bad advice on this forum? Just so I don't waste a bunch of time listening to some goofball. Had a few on last forum that after reading it for a year it was easy to weed them out. I'm new to this forum.

[Bcollins82]

Anyone got a pic of the clamp bracket? Rule states single coil over mounted to birdcage. So is the clamp on the tube or the birdcage?

Clamp bracket clamps directly to the axle tube independent from the actual birdcage. You can probably find one on BSB's website. You'll probably have an easier time finding a pic of one in steel since mod guys are more apt to use them.

[drtrkr244]

The original TWM bcages were 2 piece. The inner half was the clamp bracket or you could put the bolt thru the bottom halves if you ran it conventional. We always threaded a bolt into the tube when we ran clamped up, just to make sure it didn't move.

[Bcollins82]

And for the record, this IS an idiotic rule... It will have little to no effect on how much horsepower you use. Someone did a test a few years ago and took the LR spring completely off the car and ran nearly identical lap times. The only effective way to limit these cars at this point without sending everyone running to their chassis builder is to limit rear suspension down travel. Good luck finding a sanctioning body that will enforce that one... Lol

[MasterSbilt_Racer]

I believe you guys are overthinking this a bit... I think the 5 link dual birdcage idea is kinda cool, but I don't think its really necessary. Look at how the rear mount reacts on the birdcage right now. It doesn't actually "push" the spring into the chassis, it just slows the rate that the LR spring is unloaded when the LR drops. By slowing down that motion it effectively softens your wheel rate on the LR. I would put the spring in front with an extra soft spring, or preferably a stack setup if the clamp bracket wasn't allowed. If the clamp is allowed, there's no reason to step back 15 years on your setup. Run a shock on the birdcage to control the LR timing, and put the spring on a clamp bracket. Cars now travel nearly as much on LR as they did back when people ran clamped up cars, but they don't have the attitude of the car above because of the more balanced package being run now with the cars being down on the RF, not rocked back on the RR.

Not really. The dynamic wheel rate is as important, or moreso than the wheel rate at ride height.

[Bcollins82]

Not really. The dynamic wheel rate is as important, or moreso than the wheel rate at ride height.

Agreed. But the dynamic wheel rate with the spring behind is softer than the spring being used on that corner, if you don't account for the weight being transferred through the bars, only the spring. Softer rate=less spring rate unloading per inch of down travel, correct? So you would have to be extremely soft if you were in front to try and mimic the loading of the spring behind. I'm still not sure you could go soft enough in front to keep the load in the spring at dynamic height since the spring would unload so much faster in front. I'm sure you would have to use shock valving and bar angle as a crutch to help keep the car up and going.

[MasterSbilt_Racer]

Agreed. But the dynamic wheel rate with the spring behind is softer than the spring being used on that corner, if you don't account for the weight being transferred through the bars, only the spring. Softer rate=less spring rate unloading per inch of down travel, correct? So you would have to be extremely soft if you were in front to try and mimic the loading of the spring behind. I'm still not sure you could go soft enough in front to keep the load in the spring at dynamic height since the spring would unload so much faster in front. I'm sure you would have to use shock valving and bar angle as a crutch to help keep the car up and going.

Correct. But the front mount typically has increasing spring rate in rebound and the rear is decreasing.

[TheJet-09]

Maybe I'm misunderstanding something, but how can the spring in front gain rate (technically ride rate) during rebound if the upper and lower shock mounts are headed in different directions?

[Bcollins82]

Yep, MasterSbilt_Racer that is true. The curves would be complete opposites. You could increase lower angle, and decrease upper angle to help it some, while trying to keep thrust angles similar. You won't make it act completely the same with it in front, but from what I've experienced the amount of LR drop makes a much bigger difference than LR rate. I don't think anyone is going to switch it to the front and win a Lucas race, but this rule won't leave the cars flat and sliding either. IMO.. And Jet09. It's not that it gains rate as in loading the wheel, the motion of the front mount is faster than axle speed, making the spring act stiffer by loading faster in compression and unloading faster in rebound.

[TheJet-09]

Great suggestions by everyone and memories of things we used to run! What I don't understand is the intent of the rule. If it's engine related then address that. Make them run a 7000 RPM chip, or a 2-barrel. Don't Crate Cars run the spring behind? If it's to assist "older" cars I don't think they have an issue. LaSalle used to run a Limited class that was very competitive and not everyone had a brand name chassis. Even with the rule, where there's a will there's a way.