[Updated July 5th 2025]

JUMP TO INSTALLATION

We say bush 🇬🇧, our friends over the pond say bushing  🇺🇸, so in in the interests of consistency with other information on the topic as it relates to pinball, "bushing" is used throughout this document. The assembly itself is a stainless steel housing with sintered bronze bushings located at each end, forming the overall structure. The composite structure is referred to here as the bushing. 

This document is split into 2 parts:

• A technical introduction to the range of flipper bushings
• A detailed installation guide

You can skip ahead past the nerd-fest to the installation guide, but please please please familiarise yourself with the guide before attempting installation, even if you have replaced conventional nylon bushings, or bushings from any other manufacturer before.

Technical Info

Why?

Pinball’s magic lies in its beautiful constraints. With just two flippers and a heavy steel ball, players navigate a world of chaotic motion through precision timing and touch. It’s a game that’s instantly accessible to a beginner, yet endlessly deep for an expert — a true test of skill disguised as simplicity. At the heart of this control is the flipper, and at the heart of the flipper is the bushing. It’s the single most critical mechanical interface in the game — the pivot point through which timing, feedback, and power are transmitted. Every nuance of feel, every live catch, dead bounce, every shot angle begins here. That’s why we care. That’s why we build these and that's why we believe the obsessive attention to detail is warranted. 

Our goal for a flipper bushing was to optimise for various targets

• Low friction, even under radial and moment forces
  
• Extreme service life under loads typical of the application
• High overall rigidity for game-play consistency

However one engineering target is prioritised above all others

• Near constant friction through the stroke under variable forces. A predictable game, i.e. where input to a control vector yields rational output, is a fun game. 

Do these make the flippers more powerful?

Well if you are comparing these to nylon bushings or particularly bushings near the end of their life then these will transfer power form the crank to the bat via the flipper drive shaft with fewer frictional losses, sure. But that is really completely missing the point.  

These bushings are primarily engineered to maximise responsiveness to player input, i.e. FUN.

Material choice

At MAYA pinball we work with various materials and select specific materials for a given product based on a range of material parameters.

The most important parameter for maximising rigidity is the Young's modulus of the material, inverse floppiness. The steel types shown in the table resist bending the most. 

Another interesting but less critical parameter for this particular application is the yield strength. Yield strength is a measure of the load on a given material before it permanently deforms. The types of load exerted on a flipper bush are typically not the kinds of load that would lead to permanent deformation. This is not a shooter rod that can be pulled out and then be used as an improvised jungle-gym swing bar (yes, I have actually seen this in the wild, hosting an open session at a local pinball club 😱 - a serious consideration in the design of the Dart Ti, but I'm off track). The yield strength becomes more interesting when viewed in the light of parameters that describe the brittleness / toughness of a given material.

Without getting too deep into the weeds of material parameters, elongation at break is how much you can stretch something before it breaks. Fracture toughness is how well a material resists crack growth. Nylon is a wonderful material in that while it has a low Young's modulus, it has a huge elongation at break, meaning that cracks are not likely to form, but the low fracture toughness means that when they do form, they will rapidly extend. Nylon is also amazing in that it has self lubricating properties, making it a cost effective bushing material. However, it has in Achilles heel in the way it absorbs moisture form the air which can reduce the yield strength by 20 - 50% when saturated (more bendy). It is also prone to thermal and oxidative ageing which can lead to elongation losses at break in the region of 30% to 60% within 6 months. More bendy plus breaking at reduced bend (more brittle), plus crack propagation equals snapped flipper bushings. If you've encountered this, you will have probably seen it at the interface between the playfield side of the shaft and the flange, where radial forces from ball impacts give rise to the point of maximum moment. In a way, total failure is a blessing indicating the need to replace the bushings entirely, however, the changes in the other parameters means that even if a flipper bushing looks intact, and the shaft isn't noticeably deformed when looking down its length, it may well not be performing as new, and due to the low Young's modulus of nylon, it probably didn't play that great when fresh from the factory. 

Additives can significantly enhance nylon’s performance as a bushing material by tailoring its mechanical properties for demanding applications. Glass fibre reinforcement, for example, increases nylon’s Young’s modulus by up to 3–5 times, improving stiffness and resistance to deformation under load—critical for maintaining bushing shape and alignment. At the same time, glass-filled nylon maintains moderate elongation at break (~2–5%) for impact absorption while offering greatly improved crack resistance and dimensional stability, especially under repeated stress. Lubricant additives like PTFE or molybdenum disulfide further reduce friction and wear, improving the nylon’s performance in sliding or rotating applications. Additionally, stabilisers can protect against UV degradation and thermal ageing, ensuring that the bushing remains tough and reliable over time. These enhancements make modified nylons far more suitable for structural and load-bearing parts than unfilled, moisture-sensitive base nylon. Recent efforts by other pinball manufacturers to shift the mechanical properties of the humble nylon bushing towards the more exotic metals through use of modified nylons must be applauded. This is smart engineering between cost effectiveness and performance. At MAYA Pinball, we decided to take the path to develop a product that offers performance over everything.

Aluminium may seem like a reasonable middle-ground choice as it is also corrosion resistant and more cost effective to machine, however, there is the risk of galvanic corrosion to contend with. When two dissimilar metals like aluminium and steel are in contact—especially in the presence of moisture or conductive grime from handling during installation—a galvanic cell can form, causing the more anodic metal (aluminium) to corrode rapidly. Since base-plates and screws are often made of steel or zinc-coated steel, pairing them with an aluminium bushing creates a high-risk galvanic couple. This is all further aggravated by the fact this interface exists in a vibrating system.

1. Fretting: Vibration causes microscopic rubbing at the contact interface, removing protective oxide layers (like aluminium's natural passivation layer or chromate coatings), exposing raw metal.

2. Electrolyte Access: Vibration can pump moisture, oils, or conductive grime into tiny crevices, sustaining the galvanic reaction.

3. Mechanical Wear + Electrochemistry: Wear from vibration accelerates metal loss at the anodic (more reactive) metal—often aluminium—compounding both mechanical and chemical degradation.

In contrast, stainless steel is much closer in electrochemical potential to carbon steel and resists corrosion far better, making it a more stable and long-lasting option. Using stainless prevents seizing, pitting, and premature wear that could compromise the mechanical integrity of the flipper assembly over time.

Stainless, while fractionally less rigid than carbon steel, it is less brittle and tougher. This combined with its well known corrosion resistance properties makes it the optimum material for maximising service life. Further, it is a material that lends itself to extremely tight machining tolerances. The geometry of a bushing for a rotating shaft is critical for low friction and importantly predictable friction, particularly in an environment where the drive shaft is subject to radial impacts and forces during rotation, and the non-static moment loading that this places along the bushing.

Bronze sintered internal bushings

Oil-sintered bronze bushings are ideal for use in high-speed, high-load, and low-maintenance environments like pinball flippers.

1. Self-Lubricating

These bushings are made from powdered bronze compressed and sintered (fused) at high temperatures, forming a porous structure. These pores are impregnated with lubricant, typically oil, during manufacturing. Under operation, heat and friction cause the oil to seep out and lubricate the shaft automatically.

✅ Benefit: No need for additional lubrication — it's built-in.

2. Low Friction and Quiet Operation

The continual supply of oil reduces friction and wear between the shaft and the bushing. This results in smoother, quieter motion, which is critical in high-repeat, low-clearance mechanical assemblies.

✅ Benefit: Better feel and consistency for precise control.

3. High Wear Resistance

Bronze is naturally hard and resists galling and deformation under load, even when subjected to radial or moment loads (as flipper rods often are). Combined with the lubricating oil, the surface resists scoring and metal-to-metal contact.

✅ Benefit: Long service life.

4. Tolerant of Misalignment and Contaminants

Sintered bushings can handle a small degree of shaft misalignment and tend to shed debris better than plastic or polymer alternatives. Since the lubricant is internal, there's no sticky external grease to attract dust.

✅ Benefit: More robust performance in a real-world pinball environment.

5. Good Load-Carrying Capacity

Despite their small size, sintered bronze bushings can withstand fairly high static and dynamic loads — making them suitable for the repetitive impact forces present during flipper actuation.

✅ Benefit: Doesn't deform under repeated use or shock loads.

Geometry and friction

All three bushing types of bushing produced by MAYA Pinball have the same basic basic construction. As with standard nylon bushings, there is a flange for mounting to the flipper assembly or playfield and a bushing bore for the flipper drive shaft to rotate in. Each stainless flipper bushing has a recess at the top and bottom to accept a sintered bronze internal bushing at each end.

Types A and B which are designed for mounting into a sheet metal plate have a slightly thickened part of the main shaft above the mounting flange. This is to add as much structural mass as possible below the bore hole in the playfield, which is a hard geometric constraint. This added mass resists deformation from radial impacts from the topside of the playfield. The holes drilled in the base plate are slightly larger diameter than the playfield bore hole to allow for structural webbing on a conventional nylon bush. We used this opportunity to add as much material as possible in this area. Type C lacks this thicker part of the bore above the flange because it mounts directly to the playfield, however the smaller distance to the flange (because there is no baseplate adding distance to the fulcrum) results in inherently lower moment. 

Below the flange of each design is structural webbing to maximise resistance to deformation under radial loads and resultant moment induced by the crank pulling at the flipper drive shaft. Again, as much material as possible is added without impeding tool access to the bolts or the crank fixing to the flipper drive shaft. The flanges are also thickened relative to standard nylon bushings, but bolt positions are recessed in reliefs so that the bolting geometry remains identical to that of a conventional nylon bushing. In short, we took every opportunity to add structural mass without compromising function or serviceability.

TYPE A

TYPE B

TYPE C

The contact surface of a conventional nylon bushing, appears on first inspection to run the entire length of the shaft, but in operation this is not the case. Radial forces originating from the crank, or forces from the topside of the playfield, result in a moment with a maximum force around the flange. This coupled with the poor tolerance of the running shaft of the nylon bushings cause the flipper drive shaft to rotate on a slight diagonal relative to the main axis. This means the flipper rod, when in motion, typically contacts the topmost and bottom most parts of the shaft initially. This in turn deforms the nylon shaft increasing the overall contact area over the time of the stroke until an equilibrium is met. The driveshaft is certainly not rotating in a perfectly on axis, or even a constant diagonal axis under radial loads in a soft, loose tolerance bearing. This is why extremely worn nylon flipper bushings appear to have an out-of-round profile when looking down the empty shaft, with an hour-glass like cross section due to relatively higher amounts of wear towards the extremities. Some of this can come from repeated impact, but the most repeatable wear pattern arises from the moment induced by the crank. Juggling all of the forces at play gets mind-boggling pretty quickly, but as a player, this chaotic dynamic system is felt as a lack of consistency. The game doesn't feel as reactive or predictable as it could. In extreme cases, the flippers can feel weak and lifeless, or worse, weak and lifeless sometimes 😱. 

Frictional forces in such a dynamic system are certainly far from constant using a bushing that deforms easily. Adding structural mass to maximise rigidity, and making the tolerance to the flipper rod extremely tight helps to eliminate many variables, and and results in a step towards a more constant friction all the way through the stroke under variable loads. 

Why 2 separate internal bronze bushings?

Radial forces and associated moments are almost always present for the flipper drive shaft during play. In a more rigid bushing body, the contact pressure is much better distributed along the entire length of the bushing  However, we decided it to be a better trade off to use the more rigid but less slick material (stainless steel) through the centre of the bushing shaft where the contact pressure would be slightly lower on average over time i.e. frictional contribution of total friction through this portion is fractionally lower under moment (torque twisting) load. 

Looking at the product photography, the stainless steel band is visible in the bore, however it is recessed a fraction of a mm back from the bronze bushing away from the drive shaft. In normal operation with low radial forces, this is effectively an air gap around the flipper rod with no frictional contribution. You can feel the subtle step when pushing a (new, please) flipper rod down the shaft as the flipper rod enters the 2nd internal bushing during assembly. Under brief moments of intense radial and moment load during play, the stainless core helps to distribute the frictional forces across the entire length of the bushing better than an all-bronze internal surface. Using 2 inserts instead of one places a tighter constraint on the concentricity of the opposing machined bores. Rest assured, this was taken into consideration in manufacturing. 

The weight of the flipper and flipper drive shaft places a small axial force on the bushing when installed. This force results in a small amount of friction between the body of the flipper and the top of the bushing.  For this reason, the top surface of the bushing is multi-stage polished in a rotational motion as a final manual quality step. Of course, the relative contribution of this is very small compared to all the other forces at play, but we wanted to ensure we left no performance on the table.

If you have one of our bushings to hand you can twizzle it on a (new, please) flipper shaft and it will feel slick and tight tolerance and spin nicely. But this tells you absolutely nothing about the performance of the component under the variable loads it is designed to operate under. The same is true of any engineered system involving bearings (I'm pointing a finger at all the YouTube videos of people comparing bicycle hub "quality" using relative unloaded freewheeling time as a metric 🤢). Anyway, I'm off track again. Get the bushings into a game and enjoy them!

Some notes on bolt mounting holes

The bolt mounting holes are drilled a tiny fraction larger than those found on nylon bushings to give a little space to manoeuvre in case the playfield bore and flipper mech mounting holes are not perfectly aligned, because of course, stainless steel is not quite as pliable as nylon. Chamfers are cut around the mounting holes to allow easy bolt locating during installation. Notice the chamfers are located on the reverse side of the flange for type C bushings compared to types A and B because of course the twist screws from this era of game come down from the playfield rather than being bolted from under a base plate. We like to get the small details right...

A detail we didn't get right on the initial production run is compatibility with linear flipper mechs typically found in Bally 6803-era games. While the nylon bushings on these look near identical to type B, the sheet metal baseplate actually uses a fractionally larger size of bolt compared to the common counterparts that are compatible with type B bushings. You can get away with installing nylon bushings because the action of screwing in a bolt effectively cuts a thread into the nylon. You cannot do this into stainless steel. Unfortunately, this was discovered after completion of the initial production run, but shop-modified versions have been fitted successfully showing this to be the only parameter requiring modification. The official stance of MAYA pinball at this stage is that linear flipper mechs are not supported until a revision in a future production run. Please feel free to contact us with enquiries.

Installation Instructions

Please read each phase in its entirety prior to executing each phase. Even if you have replaced conventional nylon flipper bushings in the past, it is important to read these instructions. If in any doubt whatsoever, seek a competent technician to complete the installation.

Installation is split into 4 phases. Links here allow skipping between phases.

1. Flipper Removal and Prep
2. Removing the Old Flipper Bushing Assembly
3. Installing the New Flipper Bushings
4. Reassembling the Flipper Mechanism

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🛠 Phase 1: Flipper Removal & Prep

For all bushing types (A, B, and C)

Prepare the Machine

• Turn off and unplug your pinball machine.

• Remove the lock bar and glass.

• Lift the playfield into the service position carefully to avoid damage to any side art blades or paint finish.

Remove the Flipper Bats

• Locate the set screw or grub screw on the flipper crank (under the playfield).

• Loosen the screw with the appropriate tool (usually a 1/8" Allen key).

• For Type C compatible assemblies, you may need to loosen one or more spiked screws to free the flipper shaft.

• From the top of the playfield, pull the flipper bats upward to remove them.

⚠ If the flippers don’t slide out easily from the shaft gripping mechanism, gently twist while pulling. Avoid excessive force, which can bend shafts or damage the mech.

Inspect and Prepare the Flipper Shafts

• Examine the flipper shafts for any dings, burrs, or wear. For best performance and component longevity, MAYA Pinball recommends replacement of old worn flipper bats entirely as part of the installation.

• The shaft should be glossy and smooth. Any roughness will interfere with proper function.

• If needed, clean with a Scotch-Brite pad to remove high spots, then wipe with a clean rag to remove all debris. If the surface is remotely compromised, replace them.

Test Fit the existing flippers

• Before installing the bushes, insert the cleaned flipper shaft into one of the stainless steel bushes to test the fit.

• The shaft should slide smoothly but snugly through the bush.

⚠ Important: If you feel resistance or binding, stop immediately.
Do not force the shaft through, as this may dislodge the press-fit bronze internal bearings (despite its high-strength retaining compound) or damage the internal running surface surface.

If resistance remains after cleaning, it may be time to replace the flipper bats entirely.

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🛠 Phase 2: Removing the Old Flipper Bushing Assembly

Identify Your Mounting Style

• Type A (Sega / Data East / Stern): Bushing is mounted to a metal flipper base plate, which is then bolted to the underside of the playfield.

• Type B (Bally / Williams): Also uses a metal base plate with the bushing attached, similarly mounted under the playfield.

• Type C (Classic games): The bushing is mounted directly to the playfield using threaded nails (drive screws with a machine thread) and nuts on the underside.

Removing Type A & B Bushings

For Type A and B:

• The bushing is bolted to a metal base plate, which is itself fastened to the bottom of the playfield.

• In some cases, the bolts securing the bushing go through the base plate and into hidden nuts sandwiched between the base plate and the playfield.

⚠ Warning:

• These nuts may be completely obscured by the flipper mech and not obvious at first glance.

• If the bolts spin freely or resist removal, it likely means a nut is present and turning with the bolt.

• In this case, you'll need to remove or lower the entire flipper mechanism to access the nuts and complete the disassembly.

Removing Type C Bushings

For Type C:

• The bushing is mounted directly to the wooden playfield using threaded nails (drive screws) that were hammered in at the factory.

• These threaded nails have a machine thread, and are secured with nuts on the underside of the playfield.

To remove:

• Locate the nuts under the playfield.

• Use a nut driver or small spanner to carefully remove the nuts first, then lift away the old bushing. Pull this away in an axial motion to prevent binding on the drive screws.

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🛠 Phase 3: Installing the New Flipper Bushings

Test Fit in the Playfield (All Types)

Before installing the bushing, perform a test fit from the top side of the playfield:

• The outer diameter of the Maya bushing is slightly larger than conventional parts to maximise rigidity around the bronze insert — but still within the expected tolerance for a standard playfield hole.

• If you feel any resistance, stop and inspect the playfield hole:

  • Debris or moisture swelling can cause tightness.

  • Gently remove any raised wood fibers or high spots with fine sandpaper or a reamer.

• Do not force the bushing — it should drop in cleanly with a light press fit from the top side.

Mounting Instructions by Type

You’ve already selected the correct bushing type (A, B, or C) — follow the relevant instructions below:

🔩 Type A & Type B (Baseplate-Mounted)

• Align the bushing with the mounting holes in the flipper mechanism baseplate.

• Use the original screws or bolts to attach the bushing.

• If the entire mech had to be removed as part of step 2 due to retaining nuts, be sure to replace the retaining nuts from the opposite side of the mech. 

• Tighten all fasteners evenly and incrementally in a circular pattern do not overtighten, as this could damage the sheet metal baseplate.

• If the entire mech was removed, now is the time to offer the mech back to the playfield checking the alignment of all playfield mounting points, and then screwing all fixings back into position.

🪵 Type C (Direct-to-Playfield Mount)

• This style mounts directly to the threaded spikes (often called threaded drive screws) embedded in the wooden playfield.

• Place the bushing over the protruding threaded studs. The tolerance of the drill holes in this bush are quite tight so you may need to rock the bush onto the drive screws and *gently* tap it home (it will not deform the same way a typical nylon bush will). This is quite safe, as you have already diligently checked the tolerances in the initial part of this installation phase.

• Reinstall the nuts onto the exposed threads and gently incrementally tighten to the final position in a circular pattern across the 3 bolts.

  • ⚠ It is extremely important to avoid excessive force in tightening as this will pull the heads of the drive screws downward and risk deformation of the playing surface. This is probably one of numerous reasons that later games switched to an entirely separate mechanism. When incrementally tightening, check the top side of the playfield to check the drive screw heads are not pulling in. Take your time.

Final Check

• Insert the flipper shaft to test for smooth rotation.

• If resistance is felt:

  • Remove the shaft and check for burrs or high spots.

  • Never force the shaft — this can damage the sintered bronze bushings or compromise the retaining compound holding it in place.

• When satisfied with fit and function, you're ready to continue with Phase 4: Reassembling the Flipper Mechanism.

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🛠 Phase 4: Reassembling the Flipper Mechanism

Insert the Flipper Shaft

• From above the playfield, carefully lower the flipper bat and shaft into the installed bushing.

• The shaft should glide smoothly through the sintered bronze internal bushings.

  • If you feel any resistance, stop and inspect both the shaft and bushing for burrs, dirt, or damage.

  • Never force the shaft — doing so may damage the internal bore or compromise the press-fit of the bronze bearings.

• IMPORTANT: After installation, if the flipper ever needs to be removed, great care should be taken to ensure the flipper shaft slides up unimpeded, without force. The clamping mechanism of the crank can damage the surface of the flipper shaft. If there is any fouling on removal, use an abrasive pad to remove any high spots until the flipper is easily removable. Abrasion or coarse finish on this of this end of the shaft will not affect operation if the flipper bat is reinstalled, as this is not in contact with the running surfaces during normal operation. Forceful removal, runs risk of damaging the internal bronze bushings or compromising their mounting. 
• ADDITIONAL PRECAUTION FOR TYPE C: Flipper bats used with type C bushings have a small indented region in the drive shaft specifically for this reason. The spiked retaining screws used in these systems will absolutely displace metal by design, but the recess allows for successful clearance for removal. The geometry of the type C bushing does allow for fitment of modern type flippers if desired. However, removal of these can be extremely tricky unless you are in possession of rotary tool to completely deburr the shaft prior to attempting removal. Again aggressive sanding of this end of the shaft is fine as it is not in contact with the precision running surfaces in normal operation. 

Reattaching the Linkage

• With the flipper bat and shaft inserted from the top, reattach the linkage arm (the crank or pawl that connects to the solenoid plunger) on the underside of the playfield.

• Do not stack the flipper bushing and crank components tightly together. It’s critical that there is a small vertical gap between the bottom of the flipper bushing and the linkage arm.

  • This applies to all bushing types, whether using our stainless bushings or traditional nylon ones.

  • For Type C stainless bushings, this gap may appear quite large — this is normal and intentional.

• The linkage arm should be clamped to the shaft at a height that ensures the plunger rod moves freely inside the coil sleeve:

  • No binding.

  • No drag.

  • Full travel in and out of the coil at all times.

• Partially tighten the linkage arm clamp bolt only once you’ve confirmed smooth mechanical motion.

Set the Flipper Bat Orientation

• Rotate the flipper bat to your desired resting angle.

  • Most factory setups use an alignment hole or guide; if none is available, visually align based on playfield markings or symmetry.

• Secure the bat in place by tightening the clamp bolt on the flipper crank.

  • Ensure it's firmly clamped, but avoid overtightening and stripping the clamp.

Final Manual Mechanical Check

• Operate the flipper manually buy holding the flipper and moving it up and down and confirm:

  • Smooth movement without binding.

  • Full travel to the end-of-stroke.

  • No slippage of the crank on the shaft.

Final Powered Mechanical Check

• Lower the playfield gently back into playing position from its service position.

• Turn the machine on and get it to a state where you can operate the flippers.

• Check for slippage of the crank on the shaft (this will typically manifest as the flipper rest angle changing after a number of flips)
  • If this happens, the crank arm will need to be more firmly clamped to the flipper shaft. Loosen it slightly, realign the flipper, and then fully tighten and test again, repeating until satisfactory.  
    

Replace the glass and lock bar and play some pinball!

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