Ive been learning a lot about rear suspension and I thought a thread discussing weight transfer would be a benefit to some people.

Basically I understand weight transfer to be taking the weight off the front and putting it on the back when you launch at the track. This is to increase rear traction.

Heres some good info Ive coppied from various posts...

posted by DrkPhx,
loosen the front (shocks) which allows the front to lift and transfer the weight to the rear tires (which stiffer is better), planting them for better traction

For added weight transfer, remove the front sway bar which allows for even greater front lift. (lets the front wheels drop down more?) (and removes front weight)

posted by goober35,
If your car squats to much it will hit the bump stop and cause the rear to come back up. This will cause the rear wheels to spin.

posted by gator's 99TA,
less weight to carry up (rear suspension raises the body?) will allow for better weight distribution to the rear tires. put the pressure on teh sidewall of the tire, not the rear suspension.

posted by colonel,
You want as much weight transfer as it takes to keep the tires from spinning. weight transfer than is (not) needed for traction is just wasted energy.

forget who posted this but basically lifting the front tires any higher than about 6" is wasting energy you could be using to go forward.
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please expand on theory and more info


I have 1 question, if the rear suspension is set up to push the tires away from the body to plant them, isnt this the reverse of weight transfer? I know if the rear squated this is very bad for traction, but what is the line between trying to get weight to the rear and being able to push the rear into the track. (I think gator's 99TA was talking about this but I do not understand)

 

If you were to graph the front bumper during a launch you want a nice even rise and a nice even fall throughout the first 20-60 feet. You don't want the bumper to pop up quickly then fall slowly. you also don't want the bumper to pop up quickly then fall quickly.
Fact: Maximum weight transfer occurs when the front shocks are at Maximum extension.
The Further the front end rises, the more force is applied to the rear tires (although it will turn to wasted energy if the tires get 100% traction)

If the front end is soft and rises easily then maximum weight transfer happens within the first 2 feet of the launch. Once the shocks start collapsing, the rear tires start to unload. With a car that produces a lot of power this will cause the car to hook hard initially for the first 3-5 feet then start to spin the tires while the shocks are collapsing from full extension. If the car does not have enough power to spin the tires then the car just wasted energy on raising the front end instead of pushing the car forward.

The goal in setting up a suspension is to apply just enough force to the tires to keep them from spinning and let the rest of the force push the car forward.

For the most part, the IC is what is adjusted to get the initial hook and the shocks should be adjusted to maintain the traction throughout the 60'.

This is where adjustable shocks help.

The (rear) springs need to be stiff to transfer the force to the tires.

one exception to the "wasted energy" weight transfer is to allow the front end to rise more so the engine can rev quicker and get into its power band earlier.
(this may seem to work good for launching M6 cars with big cams but then when you shift it will just be wasted energy as you are allready in the power band but the front will pop up)


all taken from http://www.baselinesuspensions.com/i...A_Drag_Car.htm

 

Gotta move this one to Drag Racing Tech. Not seeing any calculations or engineering/design/geometry discussion here.

 

http://www.motr.biz/beenfetched_2.wmv

this video explains it all

 

nice!

 

This is just what i was looking for. I would like to know what others are doing with their shocks when the track prep is not there. I have tried everything from softening the rears and setting the front on like 8 just to see what happens. Do you want the rears on a stiffer setting on a non-hooking track or a softer setting? OR What do you do with a track that is prepped well? I am currently on 5 in the rear and 8 on the front. I cut 1.36 60's on a track that was hooking great. Also How would pinion angle help out in a situation with a slick track? Do you need less angle on a hooking track and more on a slick track? All of this plays a part in getting the weight to transfer correctly.

Sorry for rambling!!! Just wondering?

 

1.36... That is just nuts. What kind of shocks do you have BKhawk?

 

Hals with stock springs in the rear and Hals with their springs in the front. Nothing speacial. That is on a MT Drag raidial also. I think there is a few guys that have a better 60 than that in here.