LR Hike, Chain ??

[Kromulous]

IF... i am against the chain all the time, what makes more traction ?

Aero, spoiler downforce.

Weight transfer, from acceleration.

How does the 5th coil come into this mix? Does it create more weight transfer to the rear wheels, via picking up, or trying too, on the RF / Front. I understand it to be a damper to the load created by the power of the drivetrain, but that lifting force how can it be applied if the LR is against the chain already?

I am missing something, and trying to figure it out LOL, lifelong process i know LOL but anyway, thought i would ask. I know there are some great opinions and ideas to be had here.

[billetbirdcage]

IF... i am against the chain all the time, what makes more traction ?

Aero, spoiler downforce.

Weight transfer, from acceleration.

How does the 5th coil come into this mix? Does it create more weight transfer to the rear wheels, via picking up, or trying too, on the RF / Front. I understand it to be a damper to the load created by the power of the drivetrain, but that lifting force how can it be applied if the LR is against the chain already?

I am missing something, and trying to figure it out LOL, lifelong process i know LOL but anyway, thought i would ask. I know there are some great opinions and ideas to be had here.

Higher LR:

More Aero and higher COG (anti-squat) thus more weight transfer front to rear during forward acceleration, but also more weight transfer during braking and cornering. It has pro and con's just like everything else.

[Jking24]

And the lift bar/5th coil works directly off engine torque no relation to the chain/ limiter. Remember the rear is full floating well most are. You can demonstrate this by hanging the rear and jacking up the rr to simulate race condition. Their is virtually no load induced into the fifth coil when doing this

[Kromulous]

Yep, on the full floating part, but the load created by the 5 coil / shock has to be applied somewhere? Where does that force show up on the foot print, aka 4 wheel weights, each corner etc. I would think the RF would have the highest load on the wheel, and would want the 5th coil to work against it mainly.

Anyway, I took the 5th coil and moved it on the chassis side, to the left, closer to the Driver by about 1". This made a considerable impact, Car is against the chain all the time, but its not making much drive. I am running about 200lbs droop load as well.

These cars are sure fun to tinker with, but dam they can be aggravating as well LOL.

[MasterSbilt_Racer]

The 5th coil lifts the chassis at the attachment point. How it effects each wheel load is determined by that lifting point location in relationship to the Center of Gravity, and the wheel rate at each corner as the new CG location is influenced by how far each corner moves to rebalance the forces.

The 5th coil isn't really a magic traction device as far as loading goes. Its more about smoothing out load spikes and keeping the tires within the load range where they are most effective, IMO.

[billetbirdcage]

Yep, on the full floating part, but the load created by the 5 coil / shock has to be applied somewhere? Where does that force show up on the foot print, aka 4 wheel weights, each corner etc. I would think the RF would have the highest load on the wheel, and would want the 5th coil to work against it mainly.

Anyway, I took the 5th coil and moved it on the chassis side, to the left, closer to the Driver by about 1". This made a considerable impact, Car is against the chain all the time, but its not making much drive. I am running about 200lbs droop load as well.

These cars are sure fun to tinker with, but dam they can be aggravating as well LOL.

If you moved only the top of the 5th coil shock to the left? This will loosen the car on the gas. The top and bottom are separate things and will do different things, so not 100% what you moved to comment

[Kromulous]

Yes, just the top, moved 1" to the LEFT, towards the Driver. Loosen on the gas via more roll steer?

Whats the bottom do?

[billetbirdcage]

Let’s back up and I’ll explain some things that are happening (take this will a grain of salt and is my experience and point of view).

Top mount of the 5th coil:

This is where the lift arm is picking up on car. Let’s say the arm is picking up 1000#. Let’s also say the top mount is exactly at the COG of the car as far as front to back and left to right (I realize this isn’t possible at 36” unless the car had 65%+ rear weight as 32 to 38” on the lift arm would be way short of the COG)

So if that was true, when the lift arm lifted on the chassis it would remove equal weight from each of the 4 tires and put it on the rear axle. How that weight is divided to the rear tires will get covered latter but let’s just say it’s 50/50 for now. So a car with these wheel weights would look like this when the arm is lifting

Static: Wheel weights

600# 600#
600# 600#

Torque are lifts 1000# and removes 250# from each tire and places 50% on each rear tire

350# (600 – 250) 350# (600 – 250)
850# (600 – 250 + 500) 850# (600 – 250 + 500)

Now keep in mind I’m using liberties here like no shocks resisting travel and etc. This is really just with the car static and like you where power braking a car with an auto trans to put the power through the lift arm, but gets the idea across.

Say we move the top mount over to the left enough to change that 50/50% of the left and right weight to 60% left and 40% right. Now out of that 1000# it picks up on the chassis it picks up 10% more on left and 10% less on the right so you numbers would look like this

(300# off each left side tire and 200# off each right side tire)

300# (600 – 300) 400# (600 – 200)
800# (600 – 300 + 500) 900# (600 – 200 + 500)

*Note the center of the COG is roughly 54” forward of the axle for typical rear weights so the torque arm is so far behind the COG it will NEVER lift equally on the front and rear and makes these numbers IMPOSSIBLE but it’s easy for discussion purposes.

How far forward/back the top of the 5th is will affect the % it lifts on the front vs back and how much it removes from the front. The lower mount Left/Right will control how much is biased to the LR vs RR tires as well as Front/Back will effect the spring rate the arm sees as well as the poundage/leverage it has to lift on the chassis. As you can see, IMO the top vs bottom positions are completely different and should be treated separately.

###AGAIN, serious liberties taken to show some things. There are several other things going on also like: anti squat, how rear lift can change roll-steer, and etc as I was just focusing on one main point.

[fastford]

good read billet , i know you were just using generic numbers to make a point , and i may be wronge , but if you only move the top of the 5th coil in , would not the weight applied by the torque arm to the rear tires remain the same?

[billetbirdcage]

good read billet , i know you were just using generic numbers to make a point , and i may be wronge , but if you only move the top of the 5th coil in , would not the weight applied by the torque arm to the rear tires remain the same?

Generally speaking, Yes as long as that move didn’t affect the traction at the rear tires initially and lose some poundage.

Say engine at that rpm is 600# of torque and gear ratio is 6.0 so you have 3600# of torque at the tire or 43,200 inch pounds. So if the torque arm was 12” then that’s 3600# of lifting force if you had full traction, so at 36” you have 1200# (14,400 inch #). As long as the bottom is at what ever inches you can figure the max lifting force it COULD have.

Obviously moving things around and creating angle in the coilover’s travel will affect the spring rate the arm sees, thus it’s rate and time/travel relationship.

[billetbirdcage]

Max poundage at different lengths on bottom length (600# torque and 6.0 gear - no driveline loss)

32" 1350#
34" 1270#
36" 1200#
38" 1136#

[Kromulous]

Thanks for the info Billet, always appreciated.

Now, on to another question LOL.

IF... the LR is not against the chain, maxed out travel, the 5th arm can move the LR or add more travel until you reach that max travel, and then begin to lift the chassis? A lot of it would depend on the mounting position, biased one way or the other of course.

Anyway, moving it to the left created what i wanted to happen, but you guessed it, once i ran out of travel on the LR, chain, it started to loosen the car on the fuel. I see the Touring guys and they can create so much drive out of the LR that it will completely wash out the front end, and i have never been able to do that. So i want to know how to, and where that point is, so i can create more drive when i need it.

[billetbirdcage]

Krom, I'm not 100% what your question was on the last post besides maybe the last statement.

I'm not sure how to answer that to be honest, but I feel there isn't a ton of magic in the 5th coil. You can use it as a tuning tool to adjust around problems or help in a few area's but IMO you're not going to create a ton of drive with altering it.

[Kromulous]

I dont understand myself most of the time LOL. Just talking myself thru the problem we were having more or less.

Going to set up a digressive style 5th coil, and leave where it supposed to be. After talking it over with my Brother (Driver) i think we have the J bar to high on the frame and that was compounding the issue.

At our last race the car was traction hoping with the top of the 5th coil moved to the left. We talked it over and believe that once the chain was maxed out, the 5th coil would start to pick up on the car enough to unload the LR, and then it would hop, not bad but enough to where its a problem.

Going to reset everything to what we were running at the beginning of the year.

[fastford]

hey krom , are you on a solid chain or something else ?

[Kromulous]

Solid chain, but I have it mounted to slip joint with a cut down bump stop. Once the chain tightens I have about 3/8 s travel, compressing the bump stop.