Caltrac info set up" hypothesis"

[The Neens]

I cut a 1.748 60' @ approx. 7,400 lbs. & 500 rwhp with CalTracs about 2 months ago...285s with lowered pressure...Felt pretty darn smooth...

I wonder if it's just a problem for the higher HP crowd...Maybe there's a fine line that gets crossed...Just like you guys, I'm always looking for a better way to get it done...

 

[Stingpuller]

Cal Tracs

Josh is correct. You do not want the rear to squat. If the bars are set up corrrect they will work fine on a 4x4. Shocks will be the key. Ride height will play into the set up also. These trucks are heavy and most of the weight is up high. I hope to be able to test before TS but it's not looking good at this point. I need to get the new shafts into the tranny and get back to the track. Jeff

 

[minisub]

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

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

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 .

There is a Freeware program called Printkey that I have been using for years. It is much more sophisticated than just using the print screen button on the keyboard. It lets you clip just the portion of the screen you want and allows you to save the images in a variety of formats. When installed it is triggered by the print-screen keyboard button.

Found it available for download here:
http://www.webtree.ca/newlife/printkey_info.htm

 

[TrentNell]

Josh is correct. You do not want the rear to squat. If the bars are set up corrrect they will work fine on a 4x4. Shocks will be the key. Ride height will play into the set up also. These trucks are heavy and most of the weight is up high. I hope to be able to test before TS but it's not looking good at this point. I need to get the new shafts into the tranny and get back to the track. Jeff

i kinda feel the same way i know a few people that have cut 1.6* on caltracs.... and i saw some improvment also but many other things were changed at the same time so ? i fully beleive the software that the upper mount hole is better than the bottom . and thanks for the info guys i still am having a hard time with seperating weight transfer and anti squat seems like the more i learn the
less i know . I think what is hard to decide is there are so many diff opinions and you ask 1 guy and he will say that caltracs are worthless then the next guy will say the worked great and he lost .15 off of his 60 ft so far on my truck i like them better than clamps and seem to work better with fewer springs on the rear , and started to feel very good once i got a good shock on the front end . if weather holds i will be @ the strip tonight for some more testing . any other idea's or thoughts i like to open idea's and discussion and i will try that software today for some pics .

 

[DT Mag]

I believe Wide Open was cutting 1.5 60-foots at the 800hp level with there race truck and cal-tracs. But once they cranked the power up past that, they couldn't get it to hook and just broke parts.

 

[TrentNell]

another question that i will look into on my software but it will take me a while to answer but any one know how ride height effects this equation ? both front end hieght and rear end hieght ?

by theory if the rear end was higher and the front lower it would change the angle of the bar more and could be benifitial as well . but might raise the center of gravity @ the same time so ?

 

[TrentNell]

I believe Wide Open was cutting 1.5 60-foots at the 800hp level with there race truck and cal-tracs. But once they cranked the power up past that, they couldn't get it to hook and just broke parts.

thats pretty good , i can see them not being enough for those power levels .
i will move onto a 4link one day but for now would like to try and maximize the performance of the clatrcs if possible . i will be running slicks for the first time tonight and launching harder than ever before so we will see ..... might be a expensive evening :rofl:

 

[malibu795]

.....

 

[TheBac]

Trent, it seems that every time we talk about suspension, the conversation comes back to the shocks over and and over again. It just seems that they are always the stumbling point.
Since you already have the QA1's, seems to me that you're finally in a position to test your other theories. It will be interesting to see if changing the Caltrac mount will now show some improvement. Have fun and good luck!

 

[malibu795]

Trent, it seems that every time we talk about suspension, the conversation comes back to the shocks over and and over again. It just seems that they are always the stumbling point.
Since you already have the QA1's, seems to me that you're finally in a position to test your other theories. It will be interesting to see if changing the Caltrac mount will now show some improvement. Have fun and good luck!

shock control 50-75% of the suspension oscilation rate... the springs themself make up majority of the rest.

example
stif springs and soft shock will ride similar to soft springs and stiff shocks witht he soft springs on the soft side of the road.

ideally you want hte mix 50/50 pending application... high capcity run stiffer spring and softer shock

softer spring allow more body movement (yaw/pitch-side to side and front to back) and allow for more "tunability" with shocks

suspension geometery changes how effective said shocks and springs work.
example shocks @ 90* (verticle) twice as effective then a shock @ 45*
stock rear on our truck is ~60* angles

 

[TheBac]

But we already have comparatively "stiff" rear springs, dont we Adam? Especially if we clamp them? So running shocks set soft would work there?

I guess if the T-bars are completely unloaded, then they'd be considered a very "soft" spring? If so, then the QA1 or Ranchos set for very stiff would offset that?


Sorry, but suspension theory makes my head swim. Im kinda in over my head with the snubber idea already.

 

[malibu795]

But we already have comparatively "stiff" rear springs, dont we Adam? Especially if we clamp them? So running shocks set soft would work there?yes one would run a soft shock with a stiffer spring

I guess if the T-bars are completely unloaded, then they'd be considered a very "soft" spring? If so, then the QA1 or Ranchos set for very stiff would offset that?

yes thats the principle tom

 

[RPM Motorsports]

Anybody ever thought about getting rid of the leafs and making it a "4 bar" suspension? Using two more torsion bars to control the rear end. You could then jack weight from corner to corner and load what ever you wanted to. (I.E.) If your spinning the FL, jack some weight into the RR... I think it's great and funny at the same time that "Race Suspension" is being talked about for a farm truck.

 

[Stingpuller]

Set up

If you move the hole up one it will hit the tires(rear end) harder. If you take a string and go from your lower bar eye to eye and the same on the leaf spring eye to eye and go forward that will give you the instant center at your ride height. IC out front more will hit the tires with less force, if you move the IC back under the truck more it will hit the tires harder. By harder I mean it will try to walk the rear end up under the truck. I would assume that is what happened when WOP tryed more power it it started to hop. I hope to try my new set up before TS but if not I will post results after. I took pictures but have not had the time to get a USB cable to down:angel: load them. I will try to get some posted soon. Jeff

 

[Kat]

If you move the hole up one it will hit the tires(rear end) harder. If you take a string and go from your lower bar eye to eye and the same on the leaf spring eye to eye and go forward that will give you the instant center at your ride height. IC out front more will hit the tires with less force, if you move the IC back under the truck more it will hit the tires harder. By harder I mean it will try to walk the rear end up under the truck. I would assume that is what happened when WOP tryed more power it it started to hop. I hope to try my new set up before TS but if not I will post results after. I took pictures but have not had the time to get a USB cable to down:angel: load them. I will try to get some posted soon. Jeff

Most cameras have a memory card :angel:

 

[TrentNell]

well no testing tonight was loaded up slicks on @ the track ready to run ... got 1 run blew through the brakes and red lighted and waited for the other guy to leave got a 5.6 sec 60 ft :rofl: and ran a 16.** @ 112.** got rained out so no more runs .. i am mighty disapointed with myself about right now 1 run and i blew it on a side note i did launch after the red light and left pretty decent and had no tire spin just dont have a slip to tell me if it was good or not . :rofl:


but i live to fight another day .

 

[Kat]

Truck looks evil with those tires

 

[Subman]

weather looks about like it does here, at least it's warm, or is here anyway.

 

[TheBac]

Dont you just love rainy spring days at the drag strip?


You'll have another opportunity, Trent.

 

[TrentNell]

Here is the pics i think i have the bars set pretty close to represent the top bar as the spring and bottom bar as the caltrc , here is pics of using a hypethetcal of 4 lower bar mount postions and how it affect Instant center wich will be the blue dot , and the rise #'s are in the top of the screen .


lowest mount hole

then the next 3 higher mounts in order

you can see how much the changes have effected to instant center and rise, or as jeff explained how hard the hit on the rear tires are .