I have a back halved car, and want to set it set up properly befor I race it. I bought the car already back halved with the coil overs in it, but I have changed so much that It cant be right anymore. Different drivetrain, interior, front suspension! I have scales and have weighed it at all 4 corners, and have measured all the suspension points. How do I go about getting the correct springs, and 4-link properly set to the car? Any help would be great. I want to do this myself. I know I can take it to a chassis shop but there must be enough competent guys on here to help me figure it all out. Thank! Chris
First you need to find the center of gravity with you in the drivers seat race ready with fuel in. then i think you center your rear end with the two bottom bars top left is for pinion angle. and top right adjustment is for launch. then you need to find the instant center of rotation. this is all crude information Ar I'm still learning. search for my thread. Backhalving for dummies
Good go grasshopper:beer Does the car have any adjustment in the front? If there is or not. In the rear of the car is the at the ride height that you want? This is how we set up my 4link in my tube car. 1>Get the car on a level surface and make sure the car is square with the 4 link mounts and that the rear end is square in the car. This will show any tweeks in the brackets, housing and any of the mounts. 2> Gt the car at the right ride height in the back by using blocks probably under the forward link brackets on the chassis. After this measurement is done remove the coil overs, the car is now supported by the blocks and the car is at your prferred level. 3>The bottom bars should be parellel to the ground. The bottom bars will be used to set your wheelbase. 4>The driver upper bar is used to ser pinion angle. The rear mount should be mounted low next to the housing if possible then the forward mount should be pointed down. If you were to draw an imanginary line from the bottom bar rear mount forward and the same on the upper bar they will intersect towards the front of the car. At that point where they intersect is the instant center. 5>The passenger side upper bar is used for preloading the suspension. So it can be installed so that the bolts just slip in. Your rear suspension is in neutral at this point. 6>Put your shocks on to fit. When you scale the car with you in it you will be able to find the center of the car meaning if you were to put jack stands at this point the car would set perfect.. If the car weighed a total of 3000# font weight was 1600# and the rear weight would be 1400#. to get the percentages you divide 1600/3000= 53% of the weight is on the front and 47% on the back. Now if you know the wheelbase is 110" then 53% of 110" is 58" from the front spindle or 52" from the rear center. So if you take that distance and mark the rocker panel and go up to the cam center line that is the approximate center of the car. Thats the point that you want the IC to point to. Usually that point would be behind and lower. That kind of gets you in the ball park (but the park is kind of big) I am not sure where to go now without knowing the front end. Before taking anything apart look at the set up and see where the IC is now. See if any of this crap makes sense. Dave Morgan wrote a book http://www.jegs.com/i/Chassis+Book/622/CHASSIS/10002/-1, this is a great book that explains all this stuff. He also does seminars on this also http://www.davemorganseminars.com/ if you have a chance go to one even take your car, it will be some of the best money spent. Hope this helpsou: :eek2: :Smarty: I know just enough to be dangerous, I have been to three of Dave's seminars and still learning. Thanks Rick
My garsh I think I have diarreah of the keyboard. if there is anything else PM me your phone and I will call you and help you out. Thanks Rick
I try. still waiting for my book to get here so i can be a little more confused. what front adjustments are you talking about?
When you start moving weight in the car from corner to corner, you can do that by moving the platforms of the shocks front and rear. By adjusting the height of the platforms you can move alot of weight. I guess without adjustable fronts would have to physically move weight. I don't have my starting and finishing corner weights at work but when I get home I dig them up and post them to show what I mean. I changed my rear springs from 110 to 90# and re-scaled the car. Before that I had a difference of 35# between left to right rear, I couldn't get it to move because of a messed up right rear shock platform (couldn't turn it no more). It made the car go to the right at the hit of the throttle. I ended up putting 2 flats of preload and took alot out, put that also will put your suspension in a bind. So now I have nearly a balance left to right rear I think within a pound or two. I really like messing with this stuff, its quite a challenge. Can't wait till May to try it out. Thanks Rick
oh ok. pre loading the spring on the coil over. by adjusting the base tight or loose. like using air bags to move weight. do front coil overs go in the place of factor springs and shocks
If you have coil over adjustable front suspension yes you can move weight that way. When you do this you adjust diagonally. Lets say you adjust the right rear one turn up now you do the same with left front. Now you should also move the other two corners down one turn, that way the car ride height will remain the same. The weights are always taken with the driver in place. When the adjustments are made to the front its easier to lift the car up and take the weight off of the springs, when the car sets back down on the scales the suspension will be somewhat bound up because of the movement that is natural (toe in, caster, camber). So either you roll the car, which is a pain, or make them slip either with slip plates or something as simple as a heavy duty garbage bag. Now here is something on my car that I missed last time. Because I am the driver I was stuck in the car I missed alot of what was going on. What I missed was this, the upper right bar..... not sure if that was put back as the adjustments were made or left out till all the adjustment were done. Remember as the platforms are moved you create preload in the suspension, preload creates bind, bind makes for a non working suspension. So i'm not completely sure where I'm at, I think with me in the car the suspension is still neutral. Its hard to check while your sitting in the car. Ok diarrea of the keyboard again.:Comp: Like I said enjoy this stuff. Maybe more food for thought. Rick
Ok here is my info. The car when I bought it would 60" 1.4 here are the corner weights LT FRT606 RT FRT 692 LT RR 628 RT RR 537 These weights were without water and fuel, my mistake didn't realize what I was doing. These are the numbers that I ended up with. LT FRT 664 RT FRT 630 LT RR 569 RT RR 598 We couldn't move any more weight because of the rt rr shock platform was galling the shock body. Here is a video of the car after the adjustments. The car could now do a 1.28 60'. Part of the part time is better weight dist on the rear and the rear suspension was so bound up it couldn't work. Watch the launch at the release of the button the car will shoot to the right. I knew it was doing it but with the video it was really obvious. http://www.youtube.com/watch?v=l1DZZaAX5Ho&list=UUzjY74O-LmEm6Ll6AbMkvDg&index=4&feature=plcp In November I put new rear shocks and springs on ,went from a 110# spring to 95#. Now with the new shocks my adjustment was easier. LT FRT 739 RT FRT 618 RR FRT 635 RT RR 643 I went from 29# difference in the rear to 8# difference, should fix the quick right twitch that it had. But you can see how much weight can be moved by moving the shock platforms. Thanks Rick
I know the feeling, I have been to 3 Morgan seminars and it was 2 days after the 2nd one that some of it started soak in and that was only because Dave was parked in my yard and I could ask him more questions. He rams so much info down your neck in 2 days its unreal. The first one we mapped out my four link which when you make a pattern of the 4 link plates and put them on a big sheet of paper. Then you can draw out every concievable IC. that is very handy piece to have. Mine got tossed the at the first school:spank: So this spring I am going to start over. More useless info:sleep: NOT Rick
