Caltrac info set up" hypothesis"

[TrentNell]

i have been playing with my 4 link design software .... and led me to do some tinkering with my caltrac design . i saw that there are 2 mount choices on my front bracket for the bar mount . i called caltrac and the adviced me that bars the most level to the ground would perform best ..... so i checked there theroy .
setting the top bar level and conection point to duplicate the leaf i set the lower bar at both points we have to chose from and was suprized to see how much it affected instant center . for thgose that dont know about instant center it would take about 3 pages to fully describe it , but in a nut shell its effects wether the truck squats under accel or rises . 2wd trucks like to squat because of weight transfer so less instant center( meaning IC would be around the front bumper) would be benificial.... this what the lower mount would be suited for from my software predictions anyway . wich leads me to believe there setup rec. was biased to 2wd .


using the next link up actually moves the instant center much further toward the middle of the car VS the front bumper .... meaning the rear end would squat less and maybe rise under accel. this more of what we want for us 4X4 trucks so less weight is being lost off of the front tires . this is still just a theroy but off of the software's predictions it makes perfect sence. i will be moving my bar up to the next whole and will start doing some testing .
flame on

 

[Subman]

Trent, Rob and I were discussing this today, the caltracs push down on the back and by nature lift the front end which as you say is a no no in 4x4 drag racing. It got so bad on the race truck we tried blocking the right rear to hold the left front tire on the ground which was lifting on launch. We don't have caltracs for this reason, and will try a 4 link setup of some type. Might want to talk to Rob, sounds like you are both working on the same problem. Thanks for starting this tread. I'm a dumb ass on this so will enjoy reading about what people have to say on the topic.

 

[LarryJewell]

i have been playing with my 4 link design software .... and led me to do some tinkering with my caltrac design . i saw that there are 2 mount choices on my front bracket for the bar mount . i called caltrac and the adviced me that bars the most level to the ground would perform best ..... so i checked there theroy .
setting the top bar level and conection point to duplicate the leaf i set the lower bar at both points we have to chose from and was suprized to see how much it affected instant center . for thgose that dont know about instant center it would take about 3 pages to fully describe it , but in a nut shell its effects wether the truck squats under accel or rises . 2wd trucks like to squat because of weight transfer so less instant center( meaning IC would be around the front bumper) would be benificial.... this what the lower mount would be suited for from my software predictions anyway . wich leads me to believe there setup rec. was biased to 2wd .


using the next link up actually moves the instant center much further toward the middle of the car VS the front bumper .... meaning the rear end would squat less and maybe rise under accel. this more of what we want for us 4X4 trucks so less weight is being lost off of the front tires . this is still just a theroy but off of the software's predictions it makes perfect sence. i will be moving my bar up to the next whole and will start doing some testing .
flame on

Pictures would be helpful, i'm interested in the 2wd theory

 

[TheBac]

As Mr Spock would say -- "Fascinating"

So the Caltrac people never figured their bars would be used by 4x4 vehicles? Did they feel just moving the mount would help solve our traction issues, Trent? Or was this a "guess" on their part?

 

[TrentNell]

Trent, Rob and I were discussing this today, the caltracs push down on the back and by nature lift the front end which as you say is a no no in 4x4 drag racing. It got so bad on the race truck we tried blocking the right rear to hold the left front tire on the ground which was lifting on launch. We don't have caltracs for this reason, and will try a 4 link setup of some type. Might want to talk to Rob, sounds like you are both working on the same problem. Thanks for starting this tread. I'm a dumb ass on this so will enjoy reading about what people have to say on the topic.

i spoke with rob today about other things but .... i was trying to con him into building me a 4 link at the same time as yours he was willing but wants to test it on your guys truck for a while first . suprisingly the change i mentioned changed anti squat( upward drive force) from 64% to 94-120 % depending on how many inches it moved .anything over 100% will make the rear end rise instead of squat. it will never make it better than a 4 link but might make it better than anything else bolt on.

 

[TrentNell]

Pictures would be helpful, i'm interested in the 2wd theory

if i can fugure out how to do a snap shot of the screen i can show each setting and the instant center point and anti squat #'s

 

[TrentNell]

As Mr Spock would say -- "Fascinating"

So the Caltrac people never figured their bars would be used by 4x4 vehicles? Did they feel just moving the mount would help solve our traction issues, Trent? Or was this a "guess" on their part?

i think there kits was not designed for 4x4 trucks . but they new it would still stop axel wrap and gave us 2 bar mounting options and the upper mount seems to be a good match on paper anyways .

 

[Osubeaver]

if i can fugure out how to do a snap shot of the screen i can show each setting and the instant center point and anti squat #'s

Hit PrtSc (Printscreen button) -> open paint or whatever -> paste

 

[TrentNell]

Hit PrtSc (Printscreen button) -> open paint or whatever -> paste

no worky print screen doesnt do anything on the lap top . might have to try later from home .

 

[Randy5.0]

I find this very interesting. I for one, hope it works. Consistant 1.6x 60' would be pretty cool.

 

[Kat]

no worky print screen doesnt do anything on the lap top . might have to try later from home .

On my laptop it's FN print screen at same time

 

[TrentNell]

On my laptop it's FN print screen at same time

still no worky bad part is my lap top is the only one with the software i will get some pics up some how tonight or tomarrow .

 

[DT Mag]

Ask Wide Open Performance about their thoughts on launching a 4x4 with Cal-Tracs? You were there in AZ at the NHRDA Trent, did you see the back end of that race truck hop? Probably two feet of air under the rear tires.

Cal-Tracs are an amazing traction aid, I love mine on my 2wd. However, the way they are designed to work, at a certain point, I think they can hinder the way a 4wd will hook.

When the truck launches and the Cal-Tracs plant the power, the front end begins to lift, then as the front tires grab and begin to 'pull' the truck it unloads the the rear end, which induces the hop. Least thats my thoughts.

 

[TrentNell]

Ask Wide Open Performance about their thoughts on launching a 4x4 with Cal-Tracs? You were there in AZ at the NHRDA Trent, did you see the back end of that race truck hop? Probably two feet of air under the rear tires.

Cal-Tracs are an amazing traction aid, I love mine on my 2wd. However, the way they are designed to work, at a certain point, I think they can hinder the way a 4wd will hook.

When the truck launches and the Cal-Tracs plant the power, the front end begins to lift, then as the front tires grab and begin to 'pull' the truck it unloads the the rear end, which induces the hop. Least thats my thoughts.

Very good points ... i am hoping proper shock valving can calm these effect . switching to my qa1's has curred the front end rise problem and i am hoping this switch of mounting points will get the IC to help keep the weight transfer more biast towards the front . shoot who knows all we can do is try some things no one else has . thats how the rest of the sport will learn what we will consider fact one day .

 

[IdahoRob]

I clamped my springs on my first truck, worked well. I then added cal-tracs and went backwards(tried every type adjustment). I then put the clamps on with the caltracs and ended up withe the same results as without cal-tracs.

New truck and no way I put cal-tracs on. Clamped springs and bought decent shocks and out 60'd the truck with cal-tracs(about same HP) by .05.

They are great for 2x4.

 

[TrentNell]

I clamped my springs on my first truck, worked well. I then added cal-tracs and went backwards(tried every type adjustment). I then put the clamps on with the caltracs and ended up withe the same results as without cal-tracs.

New truck and no way I put cal-tracs on. Clamped springs and bought decent shocks and out 60'd the truck with cal-tracs(about same HP) by .05.

They are great for 2x4.

did you ever try that upper mounting hole rob ? i assumed you had by your statement

 

[IdahoRob]

Thats the only hole I ran Trent. I did some homework on it a long time ago.

 

[TrentNell]

Thats the only hole I ran Trent. I did some homework on it a long time ago.

thanks for the info rob not what i was hoping to hear...... but i still might be able to pick up some advantage from swaping the mount from were i have been running them to the upper holes .just the end result is still short of what i was hoping for . we will see how tommarrow goes .

 

[JoshH]

It has been a long time since I've looked at suspension setup theories, but from what I remember, even 2wd guys don't want the rear end to squat. They want the A/S to be set neutral or high. When you have the suspension set to squat you are actually pulling the tires up from the pavement. Think of it like this: of the suspension is pulling down on the back end of the car/truck, it is also pulling up on the axle with the same force and pulling the tires away from the pavement, unloading them. If the suspension is pushing up on the back of the car/truck, it is pushing down on the axle with the same force and forcing the tires into the pavement harder.

 

[Subman]

I had caltacs on my first dmax and that's the only reason Idaho Rob ever beat me.