DEEP SOURCE PASS · 2026-07-20
DATA GRADE A
Rocket Chassis
XR1 / XR1.2 4-link Super Late Model. Numbers below come from public manufacturer sheets or sanction rulebooks. We do not invent missing values.
Wheelbase
VALUE
103–105" series envelope
Lucas Oil / Super Late Model series min/max — not a Rocket-unique published chassis WB number
Published geometry & baseline numbers
J-bar start
21" (5/8" below C of pinion noted on sheet)
Camber
LF +6° / RF −5° (5.5 max noted)
Left / rear %
54.0% left / 52.5–53.0% rear
Cold PSI
LF 8–9 / RF 11–12 / LR 6–7 / RR 10–11
Stagger
0–1" front / 3–4" rear
Rotor-to-rotor (birdcage ref)
54 3/8"
Upper control arms
LF 11¼" / RF 8¼"
Lower CA (grease fit→heim)
LF 26½" / 17⅛" · RF 27½" / 19⅛"
Pinion angle (lift bar)
5°
Driveshaft
Bert/Falcon 37" · Brinn 34½"
Rocket sheets emphasize 4-link rod positions + J-bar vs numerical RC height. No published RC height in XR1.2 sheet.
XR1 platform described by Rocket as stiffer/more structurally sound; smaller adjustment scale than pre-XR1 (Rocket Chassis Evolution).
Primary sources
Always verify against your exact year chassis and series rulebook. Setup sheets change by year.
Manufacturer correction
If a number is wrong for a specific year, email the correction with a sheet PDF. We will update grade and sources.
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