Bowflex 5.1 Bench

mrresistance

Bowflex 5.1 bench owners, assemble: is this Craigslist classic mod-able or destined to wobble into retirement?

Picked up a Bowflex 5.1 because the price was “how could I not,” and now I’m trying to decide if it’s a fixer-upper or a shaky shrine to pad gaps. Before anyone says “just buy a commercial bench,” please also buy me a winning lottery ticket and a garage upgrade.

Looking for practical, tested hacks to turn this thing from “adequate for sit-ups” into “actually solid for dumbbell pressing and rows.” Specifically:

Slop and wobble fixes: Has anyone tightened up the backrest play with washers/shims/bushings? Brass sleeve in the hinge? UHMW strips on the ladder? Loctite on which bolts? Bonus points for torque specs or bolt grade upgrades that actually helped.
Bench height surgery: Can this be dropped closer to 17″ without compromising structural integrity? Swapping feet, trimming legs, removing wheels-what worked, what cracked, what voided your imaginary warranty?
Pad gap exorcism: Best DIY gap fillers that don’t turn to marshmallow under load. Yoga block + Velcro? 3D-printed bridge? Thin plywood wrapped in vinyl? Dimensions that fit the 5.1 specifically would be glorious.
Don’t slide off incline: Any seat wedge mods to stop the downhill ski feeling at 30-45 degrees? Foam wedge angles that actually keep you planted?
Width upgrade without full reupholstery: Anyone bolt on a removable wider “overlay” pad (think 11-12″) for scapular support on flat, then remove for incline to avoid shoulder pinch?
Leg hold-down attachment: Clever repurposes? Nordic curl anchor? Belt squat foot hook? Or is it just a shin-bruiser in disguise?
Real-world capacity: What loads have you safely pressed/rowed on this after mods? Not marketing numbers-actual user + dumbbells totals.
Creaks and squeaks: What lube works without dissolving the bushings/finish? Silicone spray vs lithium grease vs “shh, turn the music up.”

If you’ve Franken-benched a 5.1 into something respectable, photos, part sizes, and shameless bragging welcome. If the consensus is “it’s a glorified ab chair,” I’ll accept my fate and use it for Bulgarian split squats and existential dread.

P.S. If anyone has STL files for a gap filler or seat wedge that fits the 5.1’s dimensions, please drop them. My printer is bored and my spine is curious.

CoreCavern

Did exactly this to a 5.1 last winter. Cliff notes: it can be made respectable.

Kill the slop: My hinge had goofy clearance (holes bigger than the bolt). Swapped to a shouldered bolt + oilite bushings and thin stainless shims on each side. Blue Loctite (243) on everything, snug to no play, then back off just enough for smooth tilt. If your holes are 12 mm and the bolt is 10 mm, ream both to 12 and run an M12 shoulder bolt with a nyloc-night and day. Also added 1/16″ UHMW tape to the ladder contact faces so the hook lands tight.
Bench height: Removing wheels + swapping to 10 mm rubber bumpers dropped me ₀.8″. To get under 18″, I shortened the rear U by ₂₀ mm and sleeved the cut with 1″ × 0.083″ DOM inside, plug-welded, then repainted. Still rock solid. Don’t just hack the front legs-geometry goes weird.
Gap filler that doesn’t squish: ½″ birch ply + 10 mm firm EVA, wrapped in marine vinyl, Velcro on both pads. Mine ended up roughly 230 × 180 mm with 25 × 70 mm “tongues” that tuck under each pad-make a cardboard template because pad spacing changes slightly with angle. Zero marshmallow.
Don’t slide on incline: A 10-12° wedge cut from 2″ minicell (L200) sized to your seat pad (about 9 × 11″) keeps you planted without hip pinch. I stuck 3M Dual Lock on the underside so it pops on/off in 2 seconds.
Wider flat overlay: 11.5″ × 32″ ½″ ply + ¼″ high-density rubber. It “saddles” the stock pad with two U-clips (I 3D-printed them and lined with UHMW tape) and a short cam strap underneath. Adds _¾″ height, so I only use it for flat pressing for scapular freedom, then yank it for incline.
Leg hold-down repurpose: Works great as a Nordic anchor if you ratchet-strap the rear of the bench to a rack or plate tree so it can’t scoot. Also doubles as a belt-squat foot hook for bodyweight+chain work.
Real loads: After the above, I’m comfy pressing 100s and rowing 120s at ₁₉₀ bw. No racking drama, no flex I can feel. I wouldn’t treat it like a comp bench, but it’s miles past “ab chair.”
Creaks/squeaks: Super Lube synthetic grease on the main pivot (won’t eat plastics), dry PTFE spray on the ladder and hooks, paste wax on painted contact points. Avoid WD-40; attracts grit and wears the ladder.

If you want a printable gap-bridge or seat wedge, I’ve got STLs sized to my 5.1-PM and I’ll share.

JHookJunkie

Couple add-ons that helped mine without repeating the good stuff above:

Biggest wobble killer for me was a simple cross-brace: 1″ × ⅛″ flat bar bolted between the rear U-legs (two rivnuts per leg). Night-and-day lateral stability.
Ladder quiet/lock: heat-shrink on the hook tines + UHMW tape on the ladder faces. Adds bite, kills rattle. Dry PTFE on contact, not oil.
Pivot clean-up: shoulder bolt + flanged bronze bushings sized to your actual holes, aim for ₀.002″ clearance. Blue 243. For reference, I used 10.9 hardware and tightened to “no play then back off a hair”; torque tables put M8 ₁₈ ft-lb, M10 ₃₅-50 ft-lb depending on grade.
Height drop with integrity: low-profile glides instead of wheels and a 10-12 mm trim on the rear tube with an internal sleeve. Check pad ends up level; a 1-2 mm shim under the front feet fixed the nose-down tilt on mine.
Gap bridge that survives heavy rows: ½″ birch ply core sized to your pad gap + 6 mm EVA top, magnets epoxied into the underside corners (sticks to the frame) so it doesn’t walk when you dig your hips.
Cheap no-slip seat wedge hack: cut down a 12° yoga wedge and back it with drawer-liner rubber. Zero sliding at 30-45°.
Leg roller reuse: great tib-raise anchor and decent Nordic if you ratchet-strap the bench to plates/rack.

If anyone’s got exact 5.1 STL dims, I’ll trade you my magnet-in gap bridge file and the U-clip overlay brackets.