8 second OEM 4 link drag race chassis setup
- Thread starter Alky V6
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No one showed to take video. I bothered Ray to take one video, which was the run where the car steered to the left on take off and before I removed the preload from the RR. I only have an oral report from another racer that the car looked to launch straight after the chassis change.
Darn it Donnie. Did you at least get an in car vid?
Squid4life
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Yeah, sorry Donnie (and Charlie 
) I was really hoping to be out there but kids and sports had to come first. Of course, my ten year old asked friday if we were going to the track and I said no because of his basketball game. He wanted to skip the game he was supposed to play (and I was supposed to coach!) to go to the track. Definitely my kid! 
) I was really hoping to be out there but kids and sports had to come first. Of course, my ten year old asked friday if we were going to the track and I said no because of his basketball game. He wanted to skip the game he was supposed to play (and I was supposed to coach!) to go to the track. Definitely my kid! No. Sorry 'bout that. The camera hasn't been real dependable on the in car stuff. I did modify the mounting awhile back. I'll have to give it another try. I didn't think about it, actually. I was more concerned about getting a good baseline so that I could try the wing out, next time out.
That's funny. I had the feeling he was really interested when I picked up the wing, if it was the same kid.Yeah, sorry Donnie (and Charlie
Squid4life
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Yep, that's him. Very interested in cars and motor builds. Already knows quite a bit too. I have pics of him when he was ~4 helping build my first hot air motor. Here he is yesterday double nutting and removing the head studs of the SII motor. Proud papa. *sniff*
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Here are some chassis measurements without driver weight. I'll have to wait until I have some help to get w/driver numbers.
Fender lip heights with one turn of ARB preload on the RR.
LF 26 1/2", RF 26 1/4"
LR 28 3/4", RR 28 1/2"
Rear spring hts.
LR 9 13/16", RR 9 7/8"
Same measurements without driver and without the one turn of ARB preload on the RR.
Fender lip heights.
LF 26 5/8", RF 26 1/4"
LR 28 3/4", RR 28 1/2"
Rear spring hts.
LR 9 13/16", RR 9 13/16"
This is what I ended up with after the adjustments to the chassis I made at the track yesterday. These numbers appear to be practically neutral. Just one turn of ARB preload. The ARB preload should be much less with driver weight in the picture. It will be interesting to see what the numbers look like with driver weight.
Fender lip heights with one turn of ARB preload on the RR.
LF 26 1/2", RF 26 1/4"
LR 28 3/4", RR 28 1/2"
Rear spring hts.
LR 9 13/16", RR 9 7/8"
Same measurements without driver and without the one turn of ARB preload on the RR.
Fender lip heights.
LF 26 5/8", RF 26 1/4"
LR 28 3/4", RR 28 1/2"
Rear spring hts.
LR 9 13/16", RR 9 13/16"
This is what I ended up with after the adjustments to the chassis I made at the track yesterday. These numbers appear to be practically neutral. Just one turn of ARB preload. The ARB preload should be much less with driver weight in the picture. It will be interesting to see what the numbers look like with driver weight.
Try measuring on the frame to the ground just behind the front wheels and just in front of the rears Donnie. That should be able to give you a better idea of what the changes do. I know your car is pretty solid but the frame is the best place to measure since it's the lowest point on the car.
I'm not sure if you remember, but the car did go through a LF corner impact before I bought the car. The frame is bent. That is obvious when you see the height of the LF spring seat on the front shock body compared to the right side. I think I covered that at the beginning of this thread. I suppose I could get a baseline with the frame, but if I'm already using the fender lips, what would be the advantage of changing over to using the frame points?
Squid4life
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Donnie, did you end up getting a set of scales, or do you have someone near you over there? That is something I will be doing once I get this one on the road.
LOL I should've explained better Donnie.:redface: I remember the frame is damaged but you have to remember that you still have body bushings in the car. My point was to find a place on the frame that will only change due to the suspension being moved, not like the body. The body will always shift to some degree when changes occur from any movement. Unless you put metal bushings in then you will still have some flex and changes going on from things setling and getting older. If you pick 8 different locations you can measure on the frame and start fromn a base line then you have more complete data on what the changes will do.
Even with the frame being damaged you should still be able to tell what the changes will do or not do.
Understood.LOL I should've explained better Donnie.:redface: I remember the frame is damaged but you have to remember that you still have body bushings in the car. My point was to find a place on the frame that will only change due to the suspension being moved, not like the body. The body will always shift to some degree when changes occur from any movement. Unless you put metal bushings in then you will still have some flex and changes going on from things setling and getting older. If you pick 8 different locations you can measure on the frame and start fromn a base line then you have more complete data on what the changes will do.
Even with the frame being damaged you should still be able to tell what the changes will do or not do.
There is a small chassis shop down the road that can scale the car with electronic scales. I noticed though, when I watched them scale a friend's car, that they didn't shim the scales. I supposed the floor could have been perfectly level, but I doubt it.
I can also scale the car, but my method is old school and takes a bit more time using one mechanical scale and moving it from corner to corner. I may invest in an e setup if I find I'm having to scale cars more often.
I can also scale the car, but my method is old school and takes a bit more time using one mechanical scale and moving it from corner to corner. I may invest in an e setup if I find I'm having to scale cars more often.
Squid4life
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Intercomp-racing.com has their entry level set on sale for $1,090. I would guess with your contacts and folks you know at Barona you would make you investment back reasonably quick scaling cars, and you could use the heck out of it for personal use. I can definitely see the benefit of scaling the car.
I can definitely see the benefit of scaling the car.I agree. Scaling the car will at least point you to any problems that may exist with the chassis and suspension. It also allows you to get weight distribution numbers, determine if they're reasonable and calculate the CG of the car. I was actually able to predict how much preload weight was on the RR before I scaled the car simply by using spring heights and knowing the rate of the springs. Scaling the car confirmed my prediction, and now I can simply measure the loaded length of the spring to get an idea of how much preload exists in the rear, and on what side.Intercomp-racing.com has their entry level set on sale for $1,090. I would guess with your contacts and folks you know at Barona you would make you investment back reasonably quick scaling cars, and you could use the heck out of it for personal use.
Exciting news!!! Offsetting left to right instant center locations will dynamically control torque body roll! It has been confirmed! The amount of offset is tricky, but when the right numbers are found, the process works beautifully. The latest measurements w/driver weight coming up next.
These are the measurements of the car as they came to be after making the chassis changes at the track to correct a left steer problem at launch while the front tires were in the air.
All measurements with driver weight.
First thing checked was the amount of ARB preload present. ARB preload did exist on the RR. It was 1/12 of a turn of the adjustment buckle. One half of one flat. That was one turn without driver weight.
The remaining measurements were taken with the ARB preload neutralized.
Fender lip heights. Meaured through the centerline of the wheels.
LF 26 3/16", RF 26 3/16"
LR 28 1/2", RR 28 1/4"
Rear spring heights, loaded.
LR 9 5/8", RR 9 1/2"
This is telling me that there is very little preload present at the RR of the car. 1/8" of rear spring height difference, excluding the ARB, which is basically just taking up the slack in the adjuster.
1/8" compression on a 125 lb/in spring rate is 15.6 lbs of preload. That would be less than 1/2 turn preload on the ARB adjuster.
The track photographer has posted up pics from Saturday already, and the pics show the car with very little, if any, body roll on take off. And verbal reports from another racer is that the car left straight. Nice.
The track pics show the rearend to be very neutral as far as drop or rise in relation to the rear axle. Tire crush at the launch about 1/2 sidewall height.
All measurements with driver weight.
First thing checked was the amount of ARB preload present. ARB preload did exist on the RR. It was 1/12 of a turn of the adjustment buckle. One half of one flat. That was one turn without driver weight.
The remaining measurements were taken with the ARB preload neutralized.
Fender lip heights. Meaured through the centerline of the wheels.
LF 26 3/16", RF 26 3/16"
LR 28 1/2", RR 28 1/4"
Rear spring heights, loaded.
LR 9 5/8", RR 9 1/2"
This is telling me that there is very little preload present at the RR of the car. 1/8" of rear spring height difference, excluding the ARB, which is basically just taking up the slack in the adjuster.
1/8" compression on a 125 lb/in spring rate is 15.6 lbs of preload. That would be less than 1/2 turn preload on the ARB adjuster.
The track photographer has posted up pics from Saturday already, and the pics show the car with very little, if any, body roll on take off. And verbal reports from another racer is that the car left straight. Nice.
The track pics show the rearend to be very neutral as far as drop or rise in relation to the rear axle. Tire crush at the launch about 1/2 sidewall height.
