POLYSTOP · PRELOAD RETURN BUFFER · HARD TPU · IN DEVELOPMENT

The last inch of travel shouldn't be a frame-shock event.

A conventional bump stop is a crush device — high force by densification, runs hot, packs down, gives nothing back. POLYSTOP is a staged-elastic buffer: a thick graded annulus that compresses and bulges into its own open bore, catches the terminal energy of a bottom-out, and returns it.

See the mechanism →
POLYSTOP prototype installed on the post-runner frame POLYSTOP prototype above the leaf pack, frame side POLYSTOP rear bump stop — full-height Yoshimura diamond relief, rev F unibody POLYSTOP section view — graded wall, tapered bore, solid base with M10 bolt hole POLYSTOP front variant — stiffer and shorter for the lower control arm

Staged-Elastic Bump Stop · Rev F Unibody · Hard TPU · R&D

POLYSTOP

One watertight printed solid: a 5/16" base with an M10 bolt hole straight through it, and a graded annulus rising out of it. The wall runs thin at the top — soft first touch that won't jack a diagonal corner on a crawl dip — to thick at the base for stiff bottoming. A full-height Yoshimura diamond relief targets a force plateau in the thick wall for a softer, more repeatable catch. Rear mounts frame-side and strikes the axle perch; the front variant is stiffer and shorter because the lower control arm's motion ratio concentrates force into less stroke.

  • 2.50" OD · 4.00" rear / 3.50" front · 5/16" solid base
  • Graded wall, 6→19 mm rear · 8→21.6 mm front
  • Compress-and-bulge mechanism — not crush; low hysteresis, energy returned
  • Full-height Yoshimura relief, 8 around × 6 rows
  • M10 bolt-through, same fastener front and rear
  • Hard TPU, printed base-down with no supports; gyroid infill is the tuning knob

Pricing coming soon

Available Soon

In development — geometry is real, force numbers are model estimates until the bench says otherwise · QUESTIONS → products@sanchezlabs.us

The Mechanism

Competitors crush. This compresses and bulges.

The solid 1–2" urethane pucks on the market make force by densification — they run hot, hysterese hard, and pack down. POLYSTOP's open tapered bore gives the wall a free surface to bulge into, so it stays elastic through the whole stroke.

Graded annulus wall Wall thickness climbs from 6 mm at first touch to 19 mm at the base, so area and shape factor rise together through the stroke A smooth staged force curve for free — soft on a crawl dip, stiff at bottom-out
Open tapered bore Gives the compressed wall somewhere to go — bulge, not confined hydrostatic densification Hysteresis stays near the material floor; the stop returns energy instead of turning it into heat
Yoshimura diamond relief A full-height engineered-instability pattern that flattens the force curve into a plateau Same landing energy at a meaningfully lower peak force — a softer, repeatable catch
Front-specific variant On the lower control arm the motion ratio multiplies force and shrinks stroke, so the front part is specced stiffer and shorter — not a rear part reused A stock front doesn't waste a capable rear
Model Estimate

Same energy. Lower peak.

Both curves absorb the same landing energy. The rising-rate curve is what a plain graded stop does — the force spike arrives late and hard. The plateau is what the Yoshimura relief is shaped to do: catch earlier, hold steady, peak ~40% lower. Axes are dimensionless on purpose — the printed-TPU modulus swings every absolute number until the coupon test pins it down.

POLYSTOP plateau (Yoshimura) Plain rising-rate stop
~40% lower peak rising-rate · η≈0.40 plateau · η≈0.7 target stroke → (fraction of usable travel) force → (fraction of rising-rate peak) 0 full
First-order elastomer-compression model, η = energy ratio W/(Fpeak·stroke). Not bench data. The plain-vs-patterned control print exists specifically to measure what the pattern actually buys.
The Solver, Run On A Real Truck

Raptor Gen 1 rear — four configs, one landing.

POLYSTOP isn’t one part — it’s a parametric solver that specs a part. Here it is pointed at a Gen 1 Raptor rear: 1,500 lb corner, Sterling 10.5 under it, 315s, ~6″ of jounce. Two leaf packs (OE ~550 lb/in linear · ICON RXT progressive) × two ride heights (factory · +0.75″). Every config catches the same conservative landing — a 12″ drop at the wheel, 18,000 in-lb, no shock damping credited — inside the same 7 g peak-force budget. Softer, more progressive leaf hand-off → higher plateau-efficiency target → shorter part.

(a) Leaf force vs jounce

STOCK ~550 lb/in (linear) ICON RXT (progressive)
stop engages · factory +0.75″ lift 0 1.5k 3k 4.5k 6k 0 2 4 6 jounce from ride (in) wheel force (lb)

(b) Tangent rate — the “more progressive” story

STOCK (flat) ICON RXT (rising)
flat ~550 rising to ~630 400 450 500 550 600 650 0 2 4 6 jounce from ride (in) tangent rate (lb/in)

(c) Energy split — who eats the landing

leaf over free gap POLYSTOP (% of landing)
61% STOCK factory 47% STOCK +0.75″ 64% ICON RXT factory 51% ICON RXT +0.75″ landing energy · 18,000 in-lb 0 5k 10k 15k energy (in-lb)

(d) The catch — idealized plateau, four configs

STOCK · factory · H 5.77″ STOCK · +0.75″ · H 4.52″ ICON RXT · factory · H 5.10″ ICON RXT · +0.75″ · H 4.12″
F_peak budget · 10,500 lbf (7 g) 0 2.75k 5.5k 8.25k 11k 0 0.5 1.0 1.5 2.0 stop compression (in) force (lb)
Config Free gap Stop energy Stroke Part height Wall grade η target
STOCK · factory 3.00″ 11,025 in-lb (61%) 1.91″ 5.77″ (146 mm) 6→15.3 mm 0.55
STOCK · +0.75″ 3.75″ 8,508 in-lb (47%) 1.47″ 4.52″ (115 mm) 6→15.3 mm 0.55
ICON RXT · factory 3.00″ 11,437 in-lb (64%) 1.68″ 5.10″ (130 mm) 6→15.3 mm 0.65
ICON RXT · +0.75″ 3.75″ 9,102 in-lb (51%) 1.33″ 4.12″ (105 mm) 6→15.2 mm 0.65

Same honesty as the chart above: design numbers at E = 100 MPa. The printed-TPU modulus band (30–200 MPa) swings absolute force ~7× until the coupon test pins it; η and the plateau are targets the bench has to confirm. Landing energy is conservative — no credit taken for the shock’s bump-zone damping, which the stop supplements, not replaces.

Where It Actually Stands

What's proven, what isn't.

Proven: the rev F unibody geometry — one watertight solid, verified zero open edges, prints base-down with no supports — and a parametric solver that takes corner weight, travel, and motion ratio in and puts wall grade, height, and cone out. Not yet measured: the printed-TPU modulus (every force number swings ~7× until one compression coupon settles it), the plateau efficiency on a bench, and road miles. Every product on this site gets proven on a real vehicle before it's sold. This one is no exception, and it isn't there yet.

Development platform: 2005 F-150 SuperCrew 4×4 — the same post-runner build the pushrod suspension lives on.

See the rest of the bench →

On The Bench

Printing and solver work

QUESTIONS & FITMENT INTEREST

products@sanchezlabs.us

Not yet available for sale. Email with your platform if you want to be notified when testing lands.