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Discussion Starter #1
I have a 4 link back half 68 Dart with a big block in it that is front heavy. 58-42 on the weight percentage. 1724 up front and 1256 out back. I am considering moving the engine back at least 4-6 inches to help with the weight transfer so its more consistent on bad tracks.

I know there are a lot of variables but does anyone have any Idea how much weight you transfer doing something like that? What I would like to do it transfer at least 100 lbs and take some off the front. to get the percentage a little better.
 

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Assuming you've already moved everything you can from in front of the firewall to the rear of the car.

To move the engine/trans back a couple inches will be a big job but it will move weight onto the rear axle and off the f/e. To calculate how much, one would need to know the weight of and the center of gravity of the engine and trans assembly. Then the distance from the CG to the front spindle centerline and from the CG to the rear axle centerline.

52/48 is a pretty good percentage.

That said, what's your front suspension ... torsion bar?
 

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I used actual car scales.Built brackets to hold the motor on the frame and moved it back. No guessing.
 

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If you can find the center of gravity of your motor and trans(a close estimate is ok) how far past the front wheels it is, how it is mounted and the wheelbase of your car, you can calculate how much weight will be moved to the rear when the motor is moved x inches.
 

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Discussion Starter #5
I have scales but the biggest problem I have is I can't move anything back to even check without cutting the firewall out . If moving it back will get me 100-150 lbs more on the rear and transfer some weight I was thinking it might be worth the effort. If it was less then I didn't want to do it to this car.
 

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Move it ahead an inch or two. See what kind of weight it moves around. That will give you an idea.
 

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You don't have to move anything to figure out if it will help or not. Let's make it simpler and take the trans out. If you know the weight of your motor (let's say 700 lbs) and the centerline of it is 4" in front of your front wheels, and your wheelbase is 108", then you have 26 lbs of force pulling up on your rear end. If you move the motor back 6" you now have 13lbs pushing down on your rear end. (A change of 39lbs more on the rear). If you can give me the motor weight and centerline of how far forward, or back it is from the front wheels I can give you a good estimate of how much it will change the weights. My initial guess is a 6" move will only move 50 lbs to the rear. I am assuming the motor is mounted with a front plate and mid plate.
 

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I have scales but the biggest problem I have is I can't move anything back to even check without cutting the firewall out . If moving it back will get me 100-150 lbs more on the rear and transfer some weight I was thinking it might be worth the effort. If it was less then I didn't want to do it to this car.
So how well do you think the front and rear suspensions are working?

Have you got 6cyl torsion bars up front?
 

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Discussion Starter #9
You don't have to move anything to figure out if it will help or not. Let's make it simpler and take the trans out. If you know the weight of your motor (let's say 700 lbs) and the centerline of it is 4" in front of your front wheels, and your wheelbase is 108", then you have 26 lbs of force pulling up on your rear end. If you move the motor back 6" you now have 13lbs pushing down on your rear end. (A change of 39lbs more on the rear). If you can give me the motor weight and centerline of how far forward, or back it is from the front wheels I can give you a good estimate of how much it will change the weights. My initial guess is a 6" move will only move 50 lbs to the rear. I am assuming the motor is mounted with a front plate and mid plate.
Yes its plate mounted. I was thinking the engine and trans were around 700. The wheelbase is 111 inches and I did some measuring this AM (the car is apart right now) and the #1 spark plug looks like it is 8 inches(!) in front of the axle centerline. So looks like I will be setting it engine back at least 8 if I do it. To top it off I also have accumulated a bunch of stuff mounted up in front on the core support that has added weight in the worst place. Fuel cell, accumulator, oil and trans coolers filters etc that should be relocated if possible to help.

So how well do you think the front and rear suspensions are working?

Have you got 6cyl torsion bars up front?
Its factory torsion bar up front and has the 6cyl bars, and it is a backhalf 4 link car.
 

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Do you feel the front suspension is working good? Is it transferring the weight to the rear when the transbrake is released? Is the car pulling the front tires off the track?

Just a thought -- maybe the existing torsion bars are tired and are needing replaced. Keep in mind, there are lots of Super Stock cars like yours, running with the engine in the stock location and are pulling big wheelies.
 

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Discussion Starter #11
Edit: I measured wrong earlier my engine is actually 6 1/2 inches forward of the axle centerline.
 

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700 lbs, motor and trans, on a 111 wheelbase, moving it 8" back will move 50 lbs to the rear, moving it 6" back will move 37 lbs to rear.
 

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Discussion Starter #14
Thanks for the replies. So looks like I need to transfer and remove some weight from the front to get the percentages better. Need to replace the stock front suspension and k-frame, and put it on a diet to make the front 75-100lbs. lighter, and set the engine back. That would get it to 2900lbs and 1600 1300.... That will be 55 45 and work a lot better.
 

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If the car is apart and you are willing to cut out the firewall.
A less intrusive approach would be.
Move front wheels max forward 2"?
Move rear axle forward 2 "or more.
Move engine back 2"...should be able with header work and leave firewall alone.
All these changes are reversible should you choose a different path down the road.
Cutting out the firewall is a big modification in the eyes of a buyer someday.....IMO
 

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Look at the front suspension ...... maybe the torsion bars and shocks are spent!
 

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Discussion Starter #17
Well I got the car back on 4 wheels this week and mocked it up. Although its not finished I added lifting weights in all the areas to get it to what I figure is 20 lbs or so of actual race weight and boy did I make a difference. The engine setback looks to only have netted 45-50 lbs on the rear like some of you figured, which will definately help, but somehow I took 200 lbs off the front?!?! At first I thought the scales were off but I zeroed and tested each pad with actual weight and they are right.

Here is the scale from last summer.
77607


And here is where I am at now. This is 20 or so light on the front as I forgot the diaper and starter but still....Huge difference.
77616
 

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Sumting not right !!!

If 50 lbs of weight was shifted to the rear, it did not lose 200 on the front end.
 

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Discussion Starter #20
I think it is going to be more like 200lbs when all is said and done. I forgot the starter and diaper when I weighed it, and a few other parts. Swapped the stock front suspension out for a custom built tube K member and suspension, aluminum firewall, dash and trans tunnel, swapping the stock windshield and gasket out for lexan, made new lighter fender exit headers, and basically re engineered anything that was heavier than it needed to be. I bet saved 20 lbs in hoses just re routing them. Drilled a lot of holes in things too. Over the weekend I worked on the doors and cut 15 lbs a piece. The ol girl should work a lot better at a 52 48 weight percentage.



I knew it was going to add up but didn't think it would be that much. Its been a pain in the ass and more work than most anybody would do to an old junker like this but hey, I ain't goin to a car show.
 
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