Sprint Enduro Chassis Design
- Thread starter Flash765
- Start date
Thanks for the reply. I have all the rule books.
I was more so hoping for open discussion with fellow racers that are involved in that part of the sport.
Frame dimensions aren't that proprietary because if you can buy it, you can measure it.
Tubing on the other hand... Well, that's a whole different rabbit hole.
I was more so hoping for open discussion with fellow racers that are involved in that part of the sport.
Frame dimensions aren't that proprietary because if you can buy it, you can measure it.
Tubing on the other hand... Well, that's a whole different rabbit hole.
B-man
Member
We Animals run with the maximum wheelbase of 43.0” and rarely the minimum track width of 28". A track width of 31" seems best for my dense cranium and 6'2" frame. Ye Olde Bandit chassis of mine has 3/4" stepped spindles. Fabricated long as possible and radius rod ends that support spindles, if I recall 22" on a horizontal line center of kingpin. This was changed from original, It did make me a bit faster. I believe the tubing is 1 1/8" OD nothing magical ASFIK. I tried a 40mm rear axle and honestly could not tell the difference to 1 1/4". The bearing hanger to inside of tire is about an inch so that is a significantly shorter lever arm then most spirit chassis. Open to sharing more details.
I've been in several discussions with Al posted on this site.
Most are geared toward lto dirt chassis, but, the geometry and wheel loadings are the same, if you can make the leap, and understand that any changes are manifested at the contact patch.
Search kingpin inclination.
Being able to stack causes and effects doesn't hurt any either.
Changing the width of the kingpin centerline changes the weight transfer effects on a lefty/righty chassis.
The distance between contact patches is also relevant.
What problem are you looking to overcome?
Most are geared toward lto dirt chassis, but, the geometry and wheel loadings are the same, if you can make the leap, and understand that any changes are manifested at the contact patch.
Search kingpin inclination.
Being able to stack causes and effects doesn't hurt any either.
Changing the width of the kingpin centerline changes the weight transfer effects on a lefty/righty chassis.
The distance between contact patches is also relevant.
What problem are you looking to overcome?
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There's no problem, yet...
We built our own standard sprint chassis for this season and was fairly successful with it and are looking to adapt that chassis to road racing. Won out of the gate, got poles, set fast laps, lots of podiums and decent performance at Grands with less than stellar results, because, well, it's Grands...
Just looking for ideas on where to start the project at this point.
I know we will need overall less grip and less aggressive mechanical jacking. It's a typical Euro design but with a straight rear cross rail. 25mm front spindles and 50mm rear axle.
Current thoughts were to narrow the frame a couple of inches and bring the C's narrower by the same or more. Switch to 17's and a 40 and go max wheelbase.
Spindle C's currently at at a 22° natural caster with the kingpins centered.
1.25" tubing all around of varying wall thicknesses.
We built our own standard sprint chassis for this season and was fairly successful with it and are looking to adapt that chassis to road racing. Won out of the gate, got poles, set fast laps, lots of podiums and decent performance at Grands with less than stellar results, because, well, it's Grands...
Just looking for ideas on where to start the project at this point.
I know we will need overall less grip and less aggressive mechanical jacking. It's a typical Euro design but with a straight rear cross rail. 25mm front spindles and 50mm rear axle.
Current thoughts were to narrow the frame a couple of inches and bring the C's narrower by the same or more. Switch to 17's and a 40 and go max wheelbase.
Spindle C's currently at at a 22° natural caster with the kingpins centered.
1.25" tubing all around of varying wall thicknesses.
So less overall grip, more roll speed, less jacking.
22 degrees caster seems excessive.
Any kingpin inclination?
More kpi, less lift from outside front tire contact patch at turn in.
Chassis stiffness in correct direction can affect weight transfer.
Knowing what you want to accomplish can help.
22 degrees caster seems excessive.
Any kingpin inclination?
More kpi, less lift from outside front tire contact patch at turn in.
Chassis stiffness in correct direction can affect weight transfer.
Knowing what you want to accomplish can help.
The spindles we were using were 10°
When we're talking KPI are we talking spindle degree that everyone refers to as KPI, or the actual KPI that's affected by the static position of the C?
The caster was perfect for us on a fairly tight track, we ran a little caster out from neutral.
Most refer to kpi and spindle build angle as interchangeable. If kpi and spindle build angle do not match, this also affects geometry as related to the tire contact patch.
Some of the discussion relates to caster and kpi being separated by varying degrees affecting mechanical weight transfer, of course, related to camber.
Both caster and kpi affect the camber change curve.
Track width, tire size, air pressure, front and rear camber all affect roll speed in a straight line
Some of the discussion relates to caster and kpi being separated by varying degrees affecting mechanical weight transfer, of course, related to camber.
Both caster and kpi affect the camber change curve.
Track width, tire size, air pressure, front and rear camber all affect roll speed in a straight line
B-man
Member
Less but I am not positive on the actual dimensions. The goal was more KPI with a relatively low caster angle. The thinking and affect was stability at straight line speed. More than we had in the original of weight transfer. I don't know how to explain in words but basically I can lane change with little effort and great stability. Turn in is great and I can power thru the turn. When the toe and scaling is right she needs wheel chocks on a pool table, slightest breeze gets to rolling.
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Chris Cooper
Member
^^^ Less drag (while turning) is key 
Try pushing some karts around on the grid and see how much effort they take to turn.
Try pushing some karts around on the grid and see how much effort they take to turn.
Ted Hamilton
Helmet Painter / Racer
I wish someone made a thermoformed lexan piece that would bolt on in place of the tall nose fairing piece that sticks up. Would greatly help visibility... Interested to see your build My Jaguar is a little wider that it could be...