Ford Mustang Forums banner

1 - 18 of 18 Posts

·
Registered
Joined
·
351 Posts
I went from stock k member stock a arms and stock struts with eibach sport lines to tubular k member, tubular a arms, lakewood 90/10''s and upr 14x175 coilovers. I saw 100% zero difference in 60ft, 330ft, and 1/8 mile et. This is when I ran 8.0''s so maybe there's a difference on a faster car or maybe it makes a higher power car more consistent who knows but I was very disappointed.
 

·
Registered
Joined
·
53 Posts
Discussion Starter #3
I went from stock k member stock a arms and stock struts with eibach sport lines to tubular k member, tubular a arms, lakewood 90/10''s and upr 14x175 coilovers. I saw 100% zero difference in 60ft, 330ft, and 1/8 mile et. This is when I ran 8.0''s so maybe there's a difference on a faster car or maybe it makes a higher power car more consistent who knows but I was very disappointed.
Not the answer i was looking for... lol
That sucks man sorry to hear!
 

·
Registered
Joined
·
629 Posts
I didn't do any E.T. testing the difference. But I did weigh everything, and it was a 66 lbs savings over the factory junk. The room it gave me was reason enough for me though. The weight savings was a bonus. And when you take weight out, your car is gonna go faster, every time.
 

·
Registered
Joined
·
241 Posts
Unsprung weight reduction (those items below the spindle or axle) theoretically have a 3:1 (or greater) realization in weight reduction and ET reduction. If a crossmember were 50#’s lighter, expect an ET reduction similar to a 150# weight reduction or .15 reduction approximate. Just because a part is “tubular” or “aftermarket”, does not mean it’s lighter or better.
If I saw a guy go same ET after taking out 50# or so in unsprung weight, I would question what bushings he was using on the rotating parts. Maybe there are bushings that are binding? If it is a dedicated drag car, front end travel is very important on the slower cars or cars with limited rear tires. I would define “slower” as mid 10’s and slower.
Unsprung weight is typically wheels, brakes, control arms, crossmember on the front. Usually done in that order if not all at once.
Sometimes adding the weight taken off the front to the rear trunk as ballast will show an ET improvement.
Scales are your friend!
 

·
Registered
Joined
·
5,227 Posts
What? We have different definitions of unsprung weight. To me, unsprung weight is anything that doesn't ride on the springs. Like lower control arms, spindles, wheels, brakes, tires, etc.

Also, 3:1 ratio? Not in my experience - a little more than 1:1, but not even 2:1. Perhaps in handling, but not in drag racing. Removing 50 lbs worth of cross member will not net you .15 in ET. It's not "unsprung weight" anyway. But removing weight is always a good thing for us racer types.
 

·
Registered
Joined
·
241 Posts
Those parts is what I listed...and I’m pretty sure the engine cradle, K-frame, whatever you call it is below the coil springs. OK, maybe 1/2 of it. Plenty of engineering out there to confirm the ratio and I myself have seen it on my own drag cars. Mostly wheels and brakes for me but I know of one guy that had his spindles made from titanium.
But yes, no matter what, I agree with DragKing, if nothing else it sure does make life easier! And if you really want to obtain proven HP, make that modified / aftermarket K-Frame allow for a really BIG and boxy oil pan.
I race NHRA Super Stock and we can not use aftermarket K-Frames although we can modify for aftermarket oil pans. We also have a minimum weight.
 

·
Registered
Joined
·
31 Posts
the k member is sprung weight, unsprung IS anything not on the spring like wheels tires brakes like stated above,, also around half of the control arms are sprung because they bolt to the k member,basically if you pull down on a certain part and the car moves it is sprung
 

·
Premium Member
Joined
·
1,340 Posts
When we started out - we were using stock K-frame and Eibach drag springs strange struts. Car had 280ish hp and would leave wheels up EVERYTIME. Reaction times were excellent. I converted to UPR K-Member with coil overs 14x150# springs and the nose is like a STONE! I couldnt cut a light and spin city on the starting line. Was very disappointed. Ive spent the last 5 years trying to get the car to leave hard with the wheels up so that I can cut a decent light. I finally figured it out towards the end of this season. I don't blame the K-member - I believe its all about the stored energy in the springs. On a "slowish" bracket car I think the weight transfer is important to go rounds. If I could do it again I would use and aftermarket K-member but stock style A-arms and stock style drag springs.
 

·
Registered
Joined
·
541 Posts
When we started out - we were using stock K-frame and Eibach drag springs strange struts. Car had 280ish hp and would leave wheels up EVERYTIME. Reaction times were excellent. I converted to UPR K-Member with coil overs 14x150# springs and the nose is like a STONE! I couldnt cut a light and spin city on the starting line. Was very disappointed. Ive spent the last 5 years trying to get the car to leave hard with the wheels up so that I can cut a decent light. I finally figured it out towards the end of this season. I don't blame the K-member - I believe its all about the stored energy in the springs. On a "slowish" bracket car I think the weight transfer is important to go rounds. If I could do it again I would use and aftermarket K-member but stock style A-arms and stock style drag springs.
So what was the fix. I'm curious as I think I can knock some 60 times down if car would come up more
 

·
Premium Member
Joined
·
2,572 Posts
There is a lot going on in a drag car. How the rear suspension is set up can have as much of an impact on front end rise as anything done to the front suspension. If your instant center is way off, it would not matter how your front end is set up, your not going to transfer weight, and to transfer weight, you must first have traction. Without initial traction at the hit, the nose is not going to move at all. My car will pull 1.29-1.30 60' all day and barely make the front wheels come off of the ground. The key is to get the car driving forward, not up. Obviously the front tires just skimming or just off of the pavement is ideal because all of your power is driving the car forward. Pulling 1-2 foot high wheel stands is just wasting energy making the nose of the car go up and not forward. It looks cool, but it is not the fast way down the track.
Here is a run from yesterday. 1.30 60' car went 5.47 in the 1/8 and on the brakes slowed to a 8.79 @ 122 in the 1/4 mile. car weights 3150 with me in it. On a 26 X 8.5 tire. The front tires just barely come off the ground.

http://vid296.photobucket.com/albums/mm187/Saleen414/engine/drag%20car/bremerton%20010_zpsp4igoosy.mp4
 

·
Registered
Joined
·
5,227 Posts
That looks really gentle for a 1.30 60'. My car is more violent than that.
 

·
Premium Member
Joined
·
2,572 Posts
I take away a lot of power on the launch to keep from blowing those little tires off. I leave with only 10* of timing in the engine.
 

·
Premium Member
Joined
·
1,340 Posts
So what was the fix. I'm curious as I think I can knock some 60 times down if car would come up more
Changed alot of things over those years. I think the following made the most difference. Car doesnt 60 ft any better. But it is way more consistent round after round. Pulling the wheels up out of the beams is huge for reaction time. Gotta cut .010s or better to go rounds at our local track.

14" 130# front springs, short fast acting instant center, DA rear shocks to control the hit, anti roll bar, MT 28x9 "stick" tire, short minimal burnout, 14psi hot.
 

·
Premium Member
Joined
·
2,572 Posts
. Car doesnt 60 ft any better. Pulling the wheels up out of the beams is huge for reaction time. Gotta cut .010s or better to go rounds at our local track.
.
I will play Devils advocate for a second.....the car dose not 60' any better because you are wasting energy pulling the tires up out of the beams instead of making the car drive forward. If you got that same energy to drive the car forward, not only would your 60' be much better, it would not hurt your reaction time. Reaction time can all be manipulated with staging the car, practicing on the tree or changing certain things on the car. I improved my reaction time by changing the rear gear ratio on my car. The car now responds faster because of the gearing and I went from cutting .180-.220 on a .4 Pro tree to cutting .070 or better...all from a gear change. I can get into the .020's if I stage just a inch or so deeper. Actually, my reaction time is exactly the same, it is the cars reaction that has improved. All of my comments come from the perspective of a heads up racer. Not so good at bracket racing, .5 sportsman tree messes me up. 1/8 mile is what the car is geared for and in heads up there is no dial, just go as quick as you can.
 

·
Premium Member
Joined
·
1,340 Posts
All of my comments come from the perspective of a heads up racer. Not so good at bracket racing, .5 sportsman tree messes me up. 1/8 mile is what the car is geared for and in heads up there is no dial, just go as quick as you can.
This ^^.

I dont disagree with you. However Bracket racing an 11.90 sec stick car is worlds different than a heads up deal with an automatic.
 
1 - 18 of 18 Posts
Top