Circle track 65? Suggestions?
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5th Wheeling
Joined: Aug 2011
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1/8 or 1/4 ? Banked? Sure wish there were more places in Kalifornia that had good old fashioned fun tracks for the "Farm Leagues" as we used to call them back home. Madera Speedway is down the mtn about an hour or so away, they still have the fun punkin smashin event every year which is a blast for the kiddos!
Cargo Master
Joined: Oct 2020
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I would not run a sway bar on either end on dirt. Most dirt cars run a pretty high rear weight percentage, 53% or maybe even more yet little or no static cross weight to make the chassis very neutral. Then as the track conditions change they usually change the amount of stagger in the back and the amount of front/rear brake bias. Most if allowed use brakes on only 3 corners(none on the right front). The reason I mentioned the roll center stuff is because having it be stable and not move around a whole bunch as the chassis rolls is important to making the car feel consistent and stable. Raising or lowering the pivot will change this height without necessarily changing the ride height and that could be a nice tuning tool. A 300 6 is probably not overly heavy but it is tall and that mass is up high so something to think about.
I'm not convinced that the unsprung weight will be a real serious drawback when compared to other suspensions. Look at the size and weight of a GM metric spindle compared to a 1/2 ton Ford with no brake rotor. The I beam portion is pretty heavy but the farther it gets away from the wheel the less it is moving so a lot of that mass won't count. You won't have any ball joints just a king pin which isn't overly heavy. I think that I would make the front end so that it can use a regular racing spring with a weight jack right on top. Something like a C4 sun shell could make a good spring holder.
A leaf spring rear can work well. Not as good as some 3 or 4 bar setups when they are right but the tuning window on a leaf spring car can be pretty big. In other words it can work pretty under a lot of conditions without a lot of changes. They can be weird to rate and can sometimes do strange things. All of a sudden lose forward bite, swap out the springs and it is good again. They can loose arch and they can sometimes unwind or bend the spring eye at the front where it is tough to see but it certainly can hurt performance. I would run them using a slider at the rear instead of a shackle.
I'm not convinced that the unsprung weight will be a real serious drawback when compared to other suspensions. Look at the size and weight of a GM metric spindle compared to a 1/2 ton Ford with no brake rotor. The I beam portion is pretty heavy but the farther it gets away from the wheel the less it is moving so a lot of that mass won't count. You won't have any ball joints just a king pin which isn't overly heavy. I think that I would make the front end so that it can use a regular racing spring with a weight jack right on top. Something like a C4 sun shell could make a good spring holder.
A leaf spring rear can work well. Not as good as some 3 or 4 bar setups when they are right but the tuning window on a leaf spring car can be pretty big. In other words it can work pretty under a lot of conditions without a lot of changes. They can be weird to rate and can sometimes do strange things. All of a sudden lose forward bite, swap out the springs and it is good again. They can loose arch and they can sometimes unwind or bend the spring eye at the front where it is tough to see but it certainly can hurt performance. I would run them using a slider at the rear instead of a shackle.
Last edited by DaveMcLain; Today at 01:16 PM.
Thread Starter
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5th Wheeling
Joined: Aug 2011
Posts: 28
Likes: 3
I would not run a sway bar on either end on dirt. Most dirt cars run a pretty high rear weight percentage, 53% or maybe even more yet little or no static cross weight to make the chassis very neutral. Then as the track conditions change they usually change the amount of stagger in the back and the amount of front/rear brake bias. Most if allowed use brakes on only 3 corners(none on the right front). The reason I mentioned the roll center stuff is because having it be stable and not move around a whole bunch as the chassis rolls is important to making the car feel consistent and stable. Raising or lowering the pivot will change this height without necessarily changing the ride height and that could be a nice tuning tool. A 300 6 is probably not overly heavy but it is tall and that mass is up high so something to think about.
I'm not convinced that the unsprung weight will be a real serious drawback when compared to other suspensions. Look at the size and weight of a GM metric spindle compared to a 1/2 ton Ford with no brake rotor. The I beam portion is pretty heavy but the farther it gets away from the wheel the less it is moving so a lot of that mass won't count. You won't have any ball joints just a king pin which isn't overly heavy. I think that I would make the front end so that it can use a regular racing spring with a weight jack right on top. Something like a C4 sun shell could make a good spring holder.
A leaf spring rear can work well. Not as good as some 3 or 4 bar setups when they are right but the tuning window on a leaf spring car can be pretty big. In other words it can work pretty under a lot of conditions without a lot of changes. They can be weird to rate and can sometimes do strange things. All of a sudden lose forward bite, swap out the springs and it is good again. They can loose arch and they can sometimes unwind or bend the spring eye at the front where it is tough to see but it certainly can hurt performance. I would run them using a slider at the rear instead of a shackle.
I'm not convinced that the unsprung weight will be a real serious drawback when compared to other suspensions. Look at the size and weight of a GM metric spindle compared to a 1/2 ton Ford with no brake rotor. The I beam portion is pretty heavy but the farther it gets away from the wheel the less it is moving so a lot of that mass won't count. You won't have any ball joints just a king pin which isn't overly heavy. I think that I would make the front end so that it can use a regular racing spring with a weight jack right on top. Something like a C4 sun shell could make a good spring holder.
A leaf spring rear can work well. Not as good as some 3 or 4 bar setups when they are right but the tuning window on a leaf spring car can be pretty big. In other words it can work pretty under a lot of conditions without a lot of changes. They can be weird to rate and can sometimes do strange things. All of a sudden lose forward bite, swap out the springs and it is good again. They can loose arch and they can sometimes unwind or bend the spring eye at the front where it is tough to see but it certainly can hurt performance. I would run them using a slider at the rear instead of a shackle.
Cargo Master
Joined: Oct 2020
Posts: 2,718
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Well you're going to want to run some minus camber in the right front anyway so that might not be a problem. On the left side get the axle bent to give it some +. I'd give the right front a little more caster than the left front too while you're at it. I don't think that it'll want to push with the right set of springs in the front. It would be a good idea to rate what you've got so that you can come up with a few options. I think that the main goal is to get the chassis to be pretty neutral handling then if you feel it needs to be a little tighter or looser just adjust the stagger.
I wonder what gear it'll need? One of my customers used to pull a 6.66 at Peavely with an Allied Sportsman car at 3100lbs. That was with an engine that made 485 horsepower and turned 7200rpm. Depending on how hard you turn it and how tall of a tire you run I would think that you'll need a 7.0 or even a 7.33
I wonder what gear it'll need? One of my customers used to pull a 6.66 at Peavely with an Allied Sportsman car at 3100lbs. That was with an engine that made 485 horsepower and turned 7200rpm. Depending on how hard you turn it and how tall of a tire you run I would think that you'll need a 7.0 or even a 7.33
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