EnginesN54 N55 S55

Pinned crankhub install: the jig, the carbide law, and the chip protocol

The pinned crankhub install on N54/N55/S55: the foil-shimmed drill jig, the carbide law, depth stops, chip control with the pan off, and the factory torque-plus-angle that finishes it.

10 min readUpdated 2026-10-20Rapid Racing

Jig, stop, chips down — our schematic, drawn for this guide

This is the install canon for the pinned crankhub conversion — the VAC/Insane/SSR-class kits that turn the hub and timing sprocket into one machined body locked to the crank by dowel pins through drilled holes. The conversions guide owns the decision layer: why pins carry the load, the drilling tradeoff against the crank's hardened case, the unanswered pin-material question. This page owns the drilling discipline. The sequence below is the pinned-kit vendor's install instructions paraphrased and labeled, never copied — the sheet and drawings in your kit box govern, pin counts and pin fit differ between makers, and everything here is vendor documentation or community experience, marked as such. The factory numbers (the central-bolt torque-plus-angle that finishes the job) trace to the documents cited below.

The kit anatomy

Across the pinned market: a one-piece hub and timing gear (this is the conversion — the stock two-piece stack and its friction plates are gone), a drill jig that bolts to the crank snout and guides the bit, carbide drill bit(s), dowel pins, a new central bolt, and hardware. Kit tiers add a keyed oil-pump drive gear, a crank seal guard, gaskets and one-time hardware — the expanded SSR kit ships the full gasket set. Two pins was the original design; the market has moved to four. Prices verified in the conversions guide's comparison table: roughly $1,000 to $1,700 for the hub kit itself.

Prerequisites — read this before the car is on the lift

The pinned-kit vendor's own tool list, paraphrased: a two-post lift; a 3/4-inch breaker bar and socket for the crank bolt (their S55 breakaway note: over 440 lb-ft — the factory document says the S55 central bolt breakaway exceeds 600 Nm, and the two numbers agree); a torque wrench that reaches the factory crank-bolt spec; the crank locking tool and the full BMW timing tools; front crank seal install tools; an engine support cradle; a small 3/8-inch drill; and cutting oil or a dedicated drilling lubricant.

The vendor's minimum OEM consumables to have on the shelf: valve cover gasket set, front crank seal, two front cover seals, two VANOS bolts, oil pan bolts, oil pan gasket, coolant, engine oil. Order all of it with the kit — a pinned install opened without its consumables is an install that sits half-done.

And the boundary, stated up front because the vendor states it: this is skilled-workshop work. Their own liability line — only a skilled workshop or technician, no margin for error during this complex install — is not legalese to scare you; it is an accurate description of drilling a hardened crank nose in the car with the chips falling toward the oil pan.

The install sequence

Vendor instructions, paraphrased. Your kit's sheet and drawings govern — pin counts, depths and hardware differ between makers.

Teardown to the stack. Follow the factory disassembly process until the timing gear, oil pump gear and crank hub are removed — the engine pages carry those procedures. The VANOS assembly, timing chain and cassette come fully out or are lifted clear; the oil pump chain and cassette can stay, chain tucked out of the way.
Pan off before drilling. Remove the oil pan prior to drilling the crank snout — the vendor recommends taking the valve cover off before suspending the engine, then dropping the front subframe and pan on the cradle. Chips are controlled from below; that is the entire reason the pan is out.
Seal out, landing protected. Remove the front crank seal for access to the drill fixture and the shortened fixture bolt — with care, because the seal's landing surface must not be damaged where the new seal will sit.
The jig fit check — before any hole exists. Test the fixture's fit in the end of the crankshaft. The vendor's own record: S55 fitment very snug; one N54 with minimal play — and play means the dowel holes will not drill on-center. The fix is foil shim layers wrapped around the drill template until the fit is snug. Any doubt at this stage: contact the vendor before drilling. This is the step where the install is won or lost.
Set the depth stop before the fixture goes on. Measure the exposed length of the dowel pins (close to 0.120 inch on the reference kit). Insert the drill bit in the install tool so it protrudes slightly past that length, and put a tape or marker ring on the bit as the stop. Doing this with the jig off the crank is the only way it is done cleanly.
Mount the jig. Tighten the fixture to the crank snout with the supplied short bolt. The rotation of the hole pattern around the snout is not critical — but from the first hole onward, the fixture must not move. Every hole inherits any drift.
The carbide law. The supplied bit is straight-flute carbide: very hard, fairly brittle. Good lubrication (the vendor suggests cutting oil, gear oil or motor oil), slow-to-moderate drill speed, mild pressure. Side-load it and it snaps — and a snapped carbide bit usually fractures clean and comes out with a small pick, which is the recoverable failure. The unrecoverable ones are a dull bit that rubs and wanders, or a rushed one that bell-mouths the bore. Take your time; the holes are the hub's only alignment.
Drill the holes — two or four per your kit's drawings, through the jig's bushings, to the tape stop, lubricated, unhurried.
The chip protocol — the section that saves engines. With the drill fixture still installed, blow out each hole (brake clean and compressed air) with a shop vac running at the crank. Never blow upward — the top end is assembled and debris goes exactly where you cannot retrieve it. Wipe the internal lip at the front of the motor, passenger side, where debris accumulates — then check it with a finger. The vendor wrote that step because engines have been lost to that lip.
The pan and magnet pass. With the pan already off, inspect and clean the pan and block bottom for chips before anything closes. This is the moment the pan-off decision pays for itself.
Reassemble per the factory process — chain, sprockets, new one-piece hub, fresh central bolt. Pin insertion specifics (dry press, retained, or otherwise) come from your kit's sheet; the public instructions stop at drilling and chip control, so the sheet in the box is the authority on pin fit.
The tightening law — hold the hub, not just the crank. Clean the crank's internal threads and the bolt; oil the threads and the bolt head's underside. The vendor's method: hold the crank hub with a tool from the front of the motor while tightening the central bolt, rather than reacting all the torque through a flywheel lock alone — it eliminates the possibility of damaging the freshly installed dowel pins and stops you from twisting the entire crank. Pin the flywheel with the locking tool at the same time anyway.
The factory torque-plus-angle. 100 Nm + 360° on the N54; 100 Nm + 270° on the N55 and S55 — the factory spec, fresh bolt, no exceptions.
Timing per the factory procedure. Cam locks, TDC, tensioner tool, VANOS bolts — the engine pages carry it in full, and a hub job that ends with the timing wrong is not finished.

Factory service documentN54 crankhub central bolt — the factory torque-plus-angle that finishes the pinned installOpens in your account's service knowledge — sign-in required.

Fastener	Spec	Torque
Central bolt, N54 (`M16 x 80`)	Replace; lightly oil thread and bolt head underside	100 Nm + 360°
Central bolt, N55/S55 (`M18 x 108`)	Replace; lightly oil thread and bolt head underside	100 Nm + 270°
Dowel pins	Per your kit's sheet — must seat without bottoming	Press-fit per kit

The machinist boundary, honestly

Where this leaves DIY, in one paragraph: you are drilling a surface-hardened crank nose, in the car, through a jig whose fit you verified by feel, with depth control by tape ring, and the chips falling toward an open engine. Every one of those clauses is a normal Tuesday for a machinist and a genuinely new experience for most home mechanics. The vendor's own words — skilled workshop only — plus the market's pin-spec silence (no maker publishes pin material or hardness; the conversions guide carries that story) mean the honest recommendation is: DIY the decision, the parts research and the surrounding refresh; send the drilling to a shop that has done pinned hubs on these engines specifically. Ask them how many, and ask to see the jig shims.

The gotchas the instructions and threads agree on

The jig that walked. It is not a forum myth — the vendor documented it themselves (an N54 fixture with play). Foil shimming is the fix; doubt is the signal to stop and call.
The bit that snapped. Usually recoverable with a pick — the carbide fractures. The spare-bits note in the vendor's text exists because snaps are common enough to plan for; carry them.
Chips you cannot see. The internal lip at the front, passenger side, is the documented collection point — wipe, finger-check, repeat after blowing the holes.
Bottomed pins. The tape stop exists so the pins seat without bottoming; a proud pin holds the hub off its seat and everything downstream (seal, damper, belt) sits wrong.
Torquing against the pins. The hold-the-hub method is not preference — reacting torque through the crank alone risks the fresh dowels and twists the whole rotating assembly.
The access bill. Pan off, subframe down, cradle on — the labor is the cost, not the kit. Quoted shop hours dwarf the parts price on every row of the comparison table.

The verify checklist

Jig fit snug before drilling — shimmed if anything moves, vendor called if doubt remains.
Holes on-center, to depth, no bell-mounting; chips blown with the fixture on, vacuum running, nothing blown upward.
Internal lip wiped and finger-checked; pan and block bottom chip-free before closing.
Pins seated flush, not bottomed — per the kit sheet.
Fresh central bolt, hub held from the front, 100 Nm plus the full factory angle for your engine.
Timing set and verified the factory way — locks re-seat after two rotations, no force.
All one-time hardware renewed: pan, damper, VANOS, tensioner seals.
Oil system primed before first crank; first start watched for pressure, not hoped for.

While you're in there

The vendor's own while-apart list, paraphrased: the front crank seal ("now is the time" is their phrasing — the hub is out and the bore is in your hand); chain guides, tensioner and rails if the mileage says so (the valvetrain and timing refresh page carries the judgment); the oil pan gasket and its one-time hardware — the pan is off by definition of this job; VANOS bolts wherever touched. And the same arithmetic as every front-of-engine job on these platforms: if the head is coming off in the same build, the HCR head stud guide sequences that work; the capture plate question is answered by its own guide — a bolt capture on a pinned hub protects the one path pins don't, and one pinned-kit maker explicitly recommends pairing the two.

Where the factory numbers live

The engine pages carry the full factory teardown, torque tables and timing procedures this install assumes — N54, N55, S55 — and the overview maps all five engines. Every factory number on this page traces to the factory document ids listed in the sources; every drilling and fit instruction is the pinned-kit vendor's, paraphrased from their public install instructions current as of October 2026 — the sheet and drawings in your kit govern.

References — the research shelf

Factory sources

Questions

Can I install a pinned crankhub in my driveway?

Honestly: this is the one conversion whose own vendors say skilled workshop only — SSR's instructions end with exactly that sentence and 'no margin for error.' The drilling is precision work on a hardened surface inside an assembled engine, the pan and subframe work demands a lift and an engine support cradle, and the failure modes (a walked jig, chips in the pan) are engine-killers. A practiced home machinist with the right lift does it; everyone else should book the shop that has drilled cranks before.

Why would the drill jig need foil shims?

Because jig fit on the crank snout is a real variable — the pinned-kit vendor's own install notes record an N54 where the fixture sat with visible play, which would let the dowel holes drift off-center, fixed with foil wrapped around the drill template. S55 fitment has been snug by their report. Check fit before you drill anything; if the fixture moves at all, shim it or call the vendor.

What happens if the carbide bit snaps in the crank?

The supplied bits are straight-flute carbide — very hard and fairly brittle. Side-load one and it snaps, but the vendor's experience is that they fracture rather than bury: the stub typically comes out with a small pick. Spares are off-the-shelf items at industrial suppliers. The bigger risk than a snapped bit is a dull or rushed one — it rubs, wanders and bell-mouths the bore.

How deep do the pin holes go?

Deep enough that the dowels seat fully without bottoming out — the vendor's method is to measure the exposed pin length (close to 0.120 inch on their kit), set the bit to protrude slightly past that inside the drill guide, and put a tape or marker stop on the bit. Do this before the fixture goes on the crank. Bottoming a pin means it stands proud and the hub will not seat.

Does the hole pattern's rotation matter?

Per the vendor, no — the position of the drilled holes around the crank snout is not critical, because the one-piece hub and pins rotate with it. What is critical is that the jig does not move once the first hole is drilled: every subsequent hole inherits whatever the fixture did. Rotation free, rigidity absolute.