Birdcage Rotation w/ "Traction" Dummy Shock

[cc_3234]

On my way to NC from PA today i did a lot of thinking on the whole traction, pop-up, ect. dummy. Have we gone from trying to hold the car up with the dummy to trying to rotate the birdcage with the dummy to make forward bite. I mean 9c/0r shocks with 140-250psi to get the car to "pop". The more i think about it the more I see the birdcage just hammering into the spring with this deal. Is that the true plan or am i missing something. Thanks for the feedback.

[billetbirdcage]

This can be a drawn out subject and can get complex, but if you remember a couple basic things it isn't so hard to understand and make educated decisions.

First look at the rebound numbers for a 0 rebound shock (tested at 4.7 inches per second)

STD twin tube shock: A #0 will be around 16 to 18 pounds to pull the shock out at these speeds.

STD twin tube with low friction seals and bearings: A #0 will actaully have the shaft come out on it's own because of the low seal drag. I can't remember the numbers but I is likely close to 0 pound at that speed. The bag inside the shock will push the shaft out similar to a gas shock (with alot less force--generally). This just doesn't happen on a normal twin tube because of the seal and bearing drag is higher then the force on the shaft.

A gas pressure mono tube: This also depends on the design of the shock and gas pressure. Typically a #0 with around 75 to 100# of gas will have about 15 pound of force pushing the shaft out at 4.7" per second.

summary: At 4.7" per second -- force to extend shock

STD: 16-18 pounds
STD LOW: 0 pounds
MONO Gas: -15 pound or more

What do these do?

Obviously these are going time the climbing of the car on the bars upon throttle. Timing devise just as any onther shock on the car.

The difference comes in here:

Say the car needs this much bar angle or j-bar to climb the bars and removing some will not allow it to do so. With that in mind and you had a STD shock on the front of the LR, If you went to a high gas pressure shock you may be able to remove some of the bar angle or j-bar and have the car still climb the bars. Anytime you have less rebound or positive pressure from the shock trying to lift the car you don't need as much from bar angle or j=bar to roll the car up.

Example: say the car has a gas LR front shock set at 75# and the car gets on the bars but you would like to remove some j-bar to loosen entry. You do so and now the car won't get up on the bars (consistantly), but you like the less j-bar for entry. You could increase the gas pressure up to 150# and it will likley then consisantly climb the bars.

[cc_3234]

Ok, so i was goin to start out with the original 5c/4r (100 psi)LR we got from integra and build a 9c/0r (200 psi) shock to go with it. then for slick build a 6c/2r and i have either a 6c/0r or 4c/0r (oil) for the dummy. So basiclly i want to add comp. and psi to get the car up on the rods when i have very little rod angle and then decrease the dummy as the rod angle goes up? is that how it works and would this LR package work? Thanks for the feedback billet and let me know what you think.

[billetbirdcage]

Once you settle on a compression number that controls the hike down to your likeing, you probably won't change it alot. You may increase it if you need to hold the car up more on tracks that you are out of the throttle early and the car sets down easily. For the most part once you find the comp you like or need you will probably leave it alone and not mess with it.

Then you use rebound setting to control the timing or instant traction of the LR, adding gas pressure will reduce the number of the rebound. Example a shock that dyno's a # in rebound with 75# of gas will be less then that if you bump the presure up. So adding gas pressure you reduce the rebound and increase the compression. If you have enough gas pressure and a low rebound number (like a 1 or 0) you will have pressure lifting the car (actually like a negitive number -- -#1 or -#2 on rebound).

There are several things you can do with the LR shocks, I was just giving a example of things that would be common. Basically the more gas pressure you have the easier and quicker the car gets up, it can be used to make a car get up that wouldn't with out the help of the shock force lifting the car. This isn't the only thing the shock can be used for but should give you an understanding or the principles and help in understanding other uses that may apply.