[BLWNAWAY]

I scaled my truck last night and a guy who was there told me that it should have gone dead right but it didnt. The right rear was 109lbs lighter than the left rear with a driver in it, only 20 lbs lighter with no driver. I set it up originally by jacking up the front and then pre loading the bar to get the left front 1/8th higher than the right front and it went straight. I dont have a clue how to read my scales or the weights to tell what is going on. Here are how they read.

LF 834 RF 785


LR 679 RR 570.

It went straight as an arrow with the only problem being the IC too long making it want to wheelstand at half track. Any ideas?

 

[68Bird]

I just scaled mine a few weeks back and it went straight. This is with driver in the car and zero preload.

LF 901# RF 830#

LR 772# RR 693#

I've read / heard where you want 30-40# more weight on the RR and I've also heard you want more weight on the LR. Both theories make sense to me as to why each is better, so I don't know whats "right". I guess as long as the car is going straight, then thats the "correct" way. Lol.


Craig

 

[BLWNAWAY]

I just scaled mine a few weeks back and it went straight. This is with driver in the car and zero preload.

LF 901# RF 830#

LR 772# RR 693#

I've read / heard where you want 30-40# more weight on the RR and I've also heard you want more weight on the LR. Both theories make sense to me as to why each is better, so I don't know whats "right". I guess as long as the car is going straight, then thats the "correct" way. Lol.


Craig

Another thing is that I am nose heavy and they say no way that will work either but it appears you are as well.

 

[Joe_M]

theories about weight, IC height & length are just that...theories.

the car wants what the car wants, although depending on power and available traction those numbers may have to change in the future.

 

[race9899]

As engines increase in torque there will be a point that the chassis will throw weight onto the right rear tire with more force than the rotation of the rearend housing applies weight to the left rear tire..
When that happens, Negative Preload will be how the car has to be setup...

Where that point is is purely up to your individual car and setup....

 

[JeffMcKC]

Be careful with the preload as when you hit the brakes it will reverse it making for some very nasty driving problems

 

[68Bird]

Another thing is that I am nose heavy and they say no way that will work either but it appears you are as well.

You're only 56% up front, I don't think thats too uncommon for a light car with big engine up front. Mine is 54%.

Craig

 

[Joe_M]

some of the fastest door slammers in the world have 52-54% on the nose...dont fall for the 50/50 rule unless your running stock eliminator or something

 

[outlaw68]

those wieghts are not bad.. Hell our Bickle prostock car had 190 on the drivers side rear.. Run it and give it what it wants you might be surprised.

 

[SHAWN DAVIS]

weights

Mines almost 52 on the nose, and 60 lbs more on rt rear.dont worry about the weights as long as is goes straight. 100 lbs is not abnormal. if it goes stright with zero preload to 2 flats longer on the top rt bar you're good.If you go jacking 4 flats or so it will cause handling issues down track, especially upon shutdown

 

[BLWNAWAY]

Mines almost 52 on the nose, and 60 lbs more on rt rear.dont worry about the weights as long as is goes straight. 100 lbs is not abnormal. if it goes stright with zero preload to 2 flats longer on the top rt bar you're good.If you go jacking 4 flats or so it will cause handling issues down track, especially upon shutdown

Thanks for all the help. My truck goes very straight for about 150 to 200' where it knocks the tire off. It has a 5.29 rear gear and I knew that was too much but tried it anyway since it was in the truck already. I have a 4.10 that will go into it on Monday.

 

[BillyShope]

A tire pair yields maximum performance when equally loaded. This is true whether it's cornering or traction performance. The driveshaft torque tends to unload the RR. The greater the torque, the greater the unloading. The only way you can get maximum tractive effort from the rear tires is when they're equally loaded on launch and the only way that's going to happen is if the RR is heavier than the LR statically OR more of the weight transfer goes to the RR than the LR. The former is called "static preloading" and the latter is called "dynamic preloading." There's nothing to keep you from using a bit of both, of course. The net result can only be determined by direct measurement (either onboard instrumentation or use of a traction dyno). The fact that a car goes straight only shows that the situation isn't as bas as it could be. It does not, however, show that your car is set up properly.