On this page
- GoJak 6313 Wheel Replacement: Spec, Swap, and Upgrade Path
- What Wears Out on GoJak Wheel Dollies
- Factory Caster Spec on the 6313
- How to Measure the Existing Caster
- Matching a Heavy-Capacity Replacement
- Step-by-Step Caster Swap
- Replace in Kind or Upgrade
- Maintenance That Extends Caster Life
- Frequently asked questions
- Related Engineering Tools & Guides
GoJak 6313 wheel replacement comes down to four bolt-on casters: two 5 inch and two 4 inch nylon swivels with double ball bearing raceways.
- Zendex sells the OEM set as kit 6313-K, which also fits the G6313L and the discontinued G6200
- Each G6313 dolly is rated 1,575 lb, so a set of four dollies moves a 6,300 lb vehicle
- Replace casters as a matched set of four per dolly, never one at a time
- Aftermarket swaps must match wheel diameter, mounting height, and plate bolt pattern
- Call 844-439-4335 for fitment help; CasterHQ ships from Mansfield, Texas
The GoJak G6313 rides on four bolt-on swivel casters per dolly: two 5 inch and two 4 inch, nylon wheels on double ball bearing raceways, ANSI ICWM 2012 certified. When they crack, seize, or roll rough, replace all four as a set. The OEM path is Zendex kit 6313-K (two 6313-5 and two 5263-4 casters with new locknuts, about $140 per dolly). The aftermarket path is any heavy-capacity plate caster that matches wheel diameter, overall mounting height, and bolt pattern, sized so the four-caster set exceeds the dolly's 1,575 lb rating with margin.
GoJak 6313 Wheel Replacement: Spec, Swap, and Upgrade Path
A GoJak G6313 set moves a 6,300 lb vehicle on sixteen small wheels: four dollies, each rolling on two 5 inch and two 4 inch nylon swivel casters. Those casters are the wear item on the tool. The steel frame and ratchet mechanism outlast them by years, which is why Zendex sells the casters as a dedicated OEM replacement kit and why a dolly that drags, chatters, or refuses to swivel almost always needs wheels, not a new dolly. This guide covers what fails, the verified factory spec, how to measure before you order, OEM versus heavy-capacity aftermarket replacements, the swap procedure, and the maintenance that stretches replacement intervals. Written for body shops, dealerships, storage operators, and fleet garages running GoJaks daily.
In this guide
What Wears Out on GoJak Wheel Dollies
The casters fail long before the frame does. A vehicle dolly concentrates a quarter of a car onto four small wheels, then asks them to swivel under full load on concrete that is rarely clean.
- Raceway wear and seizure: the double ball bearing swivel raceway is unsealed. Brake dust, sandblasting media, and floor grit work into the ball track. The caster gets stiff, then stops swiveling under load, and the operator starts dragging the dolly sideways instead of steering it.
- Flat spots from parked storage: nylon resists cold flow better than soft tread compounds, but a loaded dolly parked in one spot for weeks can still develop a flat that thumps at every rotation. Worse on dollies used for long-term vehicle storage.
- Chipped and cracked wheel faces: hard nylon handles load well but is brittle at edges. Impacts with floor seams, drain grates, and lift rails chip the tread face, and each chip becomes a starting notch for a crack.
- Bent kingpins and elongated mounting holes: side-loading a stuck caster, or dropping a vehicle onto the dolly instead of pumping it up, bends the swivel section. Once the kingpin is bent the caster never tracks straight again.
- Lost or backed-off locknuts: the casters bolt to the frame with serrated locknuts. Vibration across rough floors backs off reused nuts, and a loose caster wallows out its mounting holes within weeks.
Symptoms map to causes. Hard steering under load points to raceways. Rhythmic thump points to a flat spot or chipped tread. Wander or crab-tracking points to a bent swivel. Any of these on a dolly carrying 1,500 lb of someone's vehicle is a replace-now item, not a watch item.
Factory Caster Spec on the 6313
Zendex publishes the caster spec, and it is worth reading before you order anything. The figures below come from the manufacturer's own product listings.
| Item | Factory Spec |
|---|---|
| Rated load per dolly | 1,575 lb (6,300 lb vehicle on a set of four) |
| Casters per dolly | (2) 5 inch swivel + (2) 4 inch swivel |
| Wheel material | Non-marking heavy-duty nylon |
| Swivel raceway | Double ball bearing, ANSI ICWM 2012 certified |
| Mounting | Bolt-on, reinforced steel caster plate, serrated locknuts |
| OEM replacement kit | 6313-K: (2) 6313-5 + (2) 5263-4 casters with locknuts, $140.07 list |
| Kit compatibility | G6313, G6313L, and discontinued G6200 |
| Superseded part numbers | 2006-B6 and 2006-B56 |
| OEM mounting hardware | 5/8-11 hex serrated lock nut, Zendex part 2008-B6 |
| Tire envelope | Up to 13 in wide, 36 in tall |
Two details matter for sourcing. First, the mixed diameters are intentional: the 5 inch and 4 inch casters sit at different corners of the frame, so a replacement set must preserve both sizes in the correct positions or the deck will not sit level. Second, the kit ships with fresh locknuts because Zendex expects you to discard the old ones. Serrated locknuts are single-use fasteners.
How to Measure the Existing Caster
Zendex does not publish plate dimensions, so measure your own casters before ordering aftermarket. Seven measurements fully define a plate-mount caster. Take them with the caster off the dolly and record all four corners, because a worn set rarely measures identically.
- Wheel diameter: measure across the tread face through the axle center. A worn 5 inch wheel may read 4-7/8 inch; order to the nominal size, not the worn size.
- Tread width: caliper the tread face at its widest point. Wider tread lowers point loading on soft asphalt; narrower tread swivels easier.
- Overall mounting height: floor to the top of the mounting plate, loaded flat. This is the critical dimension on a GoJak. Deck height sets the lift geometry and the foot pedal throw, so a taller caster changes how the tool closes on a tire. Match it to within 1/16 inch, and match it separately for the 5 inch and 4 inch positions.
- Plate length and width: outside dimensions of the steel top plate.
- Bolt hole pattern: center-to-center spacing of the mounting holes in both directions, plus hole diameter. The G6313 uses bolt-and-locknut mounting, so slotted plates buy you tolerance if the pattern is close but not exact.
- Swivel radius: horizontal distance from kingpin center to the farthest edge of the wheel at full swing. A larger replacement wheel with a longer swivel radius can strike the frame or an adjacent caster mid-swing. Check clearance before committing to an upsize.
- Kingpin offset: distance from kingpin center to axle center. Offset is what makes a swivel caster trail and steer; grossly different offset changes steering effort under a loaded vehicle.
If a measurement is ambiguous, photograph the caster next to a tape and send it with your RFQ. A fitment desk can identify most vehicle dolly casters from a plate photo, a height, and a diameter.
Matching a Heavy-Capacity Replacement
Size the set first, then pick the wheel material. A G6313 is rated 1,575 lb across four casters. Even distribution would put roughly 395 lb per caster, but a wheel dolly never loads evenly: the tire sits between the rollers and the load shifts corner to corner as the vehicle moves. Spec each caster at 500 to 600 lb minimum so the worst-loaded corner still runs inside its rating.
| Wheel Material | Typical Per-Caster Capacity (4-5 in) | Strengths on a Vehicle Dolly | Watch For |
|---|---|---|---|
| Nylon / glass-filled nylon (OEM) | 350 to 800 lb | Low rolling resistance, non-marking, shrugs off oil and solvents | Brittle edges chip on floor seams; loud on rough concrete |
| Phenolic | 450 to 1,000 lb | High capacity for the money, low sensitivity to shop chemicals | Chips on debris, absorbs water, poor outdoors or on wet floors |
| Polyurethane on steel core | 500 to 1,250 lb | Quiet, protects finished floors, best grip for controlled moves | Higher rolling resistance; soft grades can flat-spot in parked storage |
| Ductile or forged steel | 1,000 lb and up | Immune to flat-spotting and debris, longest service life | Marks floors, transmits vibration, hardest to swivel under load |
For most shops the practical ladder is: OEM nylon kit for a stock restore, phenolic for a budget capacity bump in dry indoor service, and polyurethane on steel for showrooms, epoxy floors, and storage duty where flat-spot resistance in the 95A hardness range earns its price. Whatever the material, every caster on the dolly must present the same mounting height as the factory pair it replaces, and the raceway should be a double ball bearing swivel equal to or better than the OEM unit.
Step-by-Step Caster Swap
The swap is a 30 to 45 minute bench job per dolly. No vehicle anywhere near the tool during the work.
- 1. Unload and stage: release the dolly from any tire, roll it to a bench, and flip it or stand it so the caster plates face you. A 47 lb dolly is a two-hand lift, not a two-person lift.
- 2. Photograph before touching anything: one photo per corner. The 5 inch and 4 inch casters occupy specific positions, and the photos settle any doubt at reassembly.
- 3. Remove the locknuts: back off the serrated locknuts and pull the bolts. Expect resistance; the serrations bite the frame. Discard every nut. Reused serrated locknuts are how casters fall off dollies.
- 4. Inspect the frame: with the casters off, check each mounting pad for cracks at the bolt holes, elongated holes, and bent plate seats. Wire-brush the pads clean. A wallowed-out hole means frame repair before new casters go on.
- 5. Bolt on the new casters: correct diameter to correct corner, fresh locknuts, tightened in a cross pattern until the serrations seat and the plate cannot be shifted by hand. Do not stack washers to correct a height mismatch; return the caster and get the right height.
- 6. Bench check: set the dolly on a known-flat surface. All four wheels touch, no rock, every caster swivels 360 degrees by hand without notchiness.
- 7. Load test: first lift on a low-value vehicle or a shop cart, one full pump-up, a straight push, a sideways push, and a tight spin. Listen for clicks from the raceways and recheck nut torque after the first week of service.
Replace in Kind or Upgrade
Replace in kind when the tool was doing its job; upgrade when the failure tells you the spec was wrong. The failure mode is the diagnosis.
- Replace in kind (OEM 6313-K): casters wore out over years of normal service, the dolly stays inside its 1,575 lb rating, floors are ordinary shop concrete. About $140 per dolly restores factory geometry with zero fitment risk, and the kit covers the G6313L and old G6200 frames too.
- Upgrade the wheel material: flat spots from storage duty call for harder polyurethane or steel. Chipped nylon from rough floors calls for polyurethane's impact tolerance. Raceway seizures in blasting or bodywork dust call for a sealed or serviceable swivel with a grease fitting.
- Upgrade capacity margin: if the shop routinely positions trucks and SUVs at the top of the rating, spec aftermarket casters with per-wheel ratings 50% above the arithmetic share. The dolly frame rating still governs; heavier casters do not raise the 1,575 lb limit.
- Do not upgrade past the tool: a 6 inch caster on a frame built for 5 inch changes deck height, pedal geometry, and swivel clearance. If the vehicles outgrew the G6313, the answer is a higher-capacity dolly, not taller wheels on this one.
Maintenance That Extends Caster Life
Five habits roughly double the service interval on dolly casters. All five cost minutes, not dollars.
- Store dollies unloaded: the single biggest lever. A GoJak hanging on a wall bracket or parked empty cannot flat-spot, and its raceways are not sitting under load collecting grit.
- Sweep the travel path: nylon and phenolic chip on exactly the debris a body shop makes: fastener heads, glass, weld spatter. A 60 second sweep before a move is cheaper than a caster kit.
- Blow out and lubricate raceways quarterly: compressed air through the swivel head, then a light machine oil worked in while spinning the fork. Skip heavy grease in dusty shops; it turns the raceway into a lapping compound carrier.
- Recheck locknut torque quarterly: one wrench pass across all sixteen nuts on a four-dolly set. Any nut that moved goes in the trash and gets replaced, not retightened and forgotten.
- Rotate parked storage positions: for dollies that must sit loaded under stored vehicles, roll the vehicle a quarter wheel-turn monthly so the same tread patch is not loaded all season.
Key takeaways
- The G6313 uses two 5 inch and two 4 inch bolt-on nylon swivel casters with double ball bearing raceways, ANSI ICWM 2012 certified.
- OEM kit 6313-K ($140.07, parts 6313-5 and 5263-4 with locknuts) fits the G6313, G6313L, and discontinued G6200.
- Measure diameter, tread width, mounting height, plate size, bolt pattern, swivel radius, and offset before ordering aftermarket.
- Mounting height is the make-or-break dimension: it sets deck height and pedal geometry, so match it per corner.
- Spec 500 to 600 lb per caster minimum so uneven loading stays inside rating on a 1,575 lb dolly.
- Replace in sets of four with fresh serrated locknuts; never reuse the old nuts.
- Unloaded storage, swept floors, and quarterly raceway service roughly double caster life.
Frequently asked questions
What size casters does the GoJak 6313 use?
Each G6313 dolly runs two 5 inch and two 4 inch swivel casters with non-marking nylon wheels on double ball bearing raceways, ANSI ICWM 2012 certified. Zendex sells the OEM set as kit 6313-K, containing two 6313-5 and two 5263-4 casters with new locknuts. The same kit fits the left-pedal G6313L and the discontinued G6200.
Can I replace just one caster on a GoJak?
Mechanically yes, practically no. One fresh caster among three worn ones sits taller, takes a disproportionate share of the corner load, and tilts the deck the lift geometry depends on. The labor to change one caster is the same flip-and-bolt job as changing four. Replace per-dolly sets and keep the removed serviceable casters as emergency spares.
Do I have to buy the OEM Zendex kit?
No. The casters are standard bolt-on plate swivels. Any industrial caster that matches wheel diameter, overall mounting height, plate bolt pattern, and swivel clearance will bolt up, and heavy-capacity phenolic or polyurethane-on-steel options can outperform the factory nylon in specific environments. The OEM kit's advantage is zero measurement risk: it is a drop-in with correct hardware. Aftermarket only makes sense after you have measured your casters.
What load rating should replacement casters have?
The dolly is rated 1,575 lb across four casters, which averages roughly 395 lb per caster. Loading is never even on a wheel dolly, so spec each replacement at 500 to 600 lb minimum. Going higher costs little and buys raceway life, but it does not raise the dolly's rating; the frame and ratchet mechanism still limit the tool to 1,575 lb.
Should I switch from nylon to polyurethane wheels?
Switch if your floors or duty cycle punish nylon. Polyurethane on a steel core is quieter, protects epoxy and polished floors, and resists edge chipping from debris impacts. The trade is higher rolling resistance, so a loaded dolly takes more push force to start moving. For long-term loaded storage choose a harder polyurethane in the 95A range or keep hard wheels, because soft tread compounds flat-spot under weeks of static load.
How often should GoJak casters be inspected?
Monthly in daily-use shops: spin each wheel for roughness, swivel each fork through 360 degrees, look for tread chips and cracks, and check locknut tightness. Quarterly, blow out the raceways and oil them. Replace immediately on any seized swivel, visible crack, flat spot you can feel in the roll, or a caster that no longer sits flat, because a failure under a suspended vehicle is a safety event, not a maintenance event.
Need Casters Matched to a Vehicle Dolly?
CasterHQ matches replacement casters to wheel dollies, shop equipment, and OEM tools from a photo, a mounting height, and a bolt pattern. Send your measurements and we return a fitment with per-wheel capacity math, in OEM-equivalent nylon or upgraded phenolic and polyurethane-on-steel builds. Same-day RFQ response; stock sizes ship fast from the Mansfield, Texas warehouse.
References & Standards Cited
- Zendex Tool Corp, GoJak G6313 product listing and specification table, zendextool.com, retrieved July 2026
- Zendex Tool Corp, 5 inch & 4 inch Replacement Caster Kit 6313-K product listing, zendextool.com, retrieved July 2026
- Zendex Tool Corp, G6313 OEM parts catalog (2008-B6 lock nut, 2001-63 inner ratchet and axle), zendextool.com, retrieved July 2026
- ANSI ICWM 2012, Institute of Caster and Wheel Manufacturers performance standard
- CasterHQ fitment desk records, vehicle dolly and shop equipment retrofits, 2021-2026
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Shop All CastersCall 844-439-4335Jordan Wilson
Founder of CasterHQ.com. Works directly with engineers, MRO buyers, and procurement teams across material handling, healthcare, food service, aerospace, and OEM. CasterHQ stocks Albion, Hamilton, P&H, Colson, Faultless, and the in-house Durastar series from a Texas warehouse and retrofits OEM fitments from dimensional drawings when brands discontinue parts.