Crank bolt capture install: what it fixes, what it can't, and the clocking problem
The crank bolt capture install on N54/N55/S55: what a capture does and doesn't fix, the bolt-head clocking problem, kit torque specs, and why it belongs on the hub job.
The crank bolt capture is the smallest part in the crankhub conversation and the one with the clearest contract: a plate that surrounds the factory central bolt's head and locks to the damper's fasteners, so the bolt physically cannot rotate backward. This is its install canon — the VTT Crank Bolt Capture (CBC) and Kies Bolt Lock class of kits, plus what the honest tier below them looks like. The conversions guide owns the decision tree; this page owns what the part does, what it cannot do, and the clocking problem that governs when you install it. Everything kit-specific below is vendor documentation, paraphrased and labeled — the sheet in your kit governs. The factory numbers (the central-bolt law, the damper screws) trace to the documents cited below.
What it fixes — and what it doesn't
The crankhub failure story has two paths, and the capture addresses exactly one:
- Bolt back-off. The central bolt loses tension — a reused bolt, an interrupted angle stage, plain loosening over years of torque reversal. Clamp load falls, and the friction stack loses capacity. This is the path the capture kills: the bolt head is captured against the damper, rotation is mechanically blocked, clamp load stays where the torque-plus-angle put it.
- Friction-stack overload. A torque spike (money shift, launch, raised limiter) exceeds the stack's capacity while the bolt is still tight. The hub rotates relative to the crank regardless of bolt tension. The capture does nothing here — and both major vendors are honest about it in print: one states a capture "helps prevent the bolt from backing out, but is not a complete repair for every crank-hub failure mode" and "does not create a keyed or splined connection"; the other says flatly that with their lock fitted "it is still possible to spin a crank hub," and recommends pairing it with a four-pin conversion.
That vendor honesty is why this part earns a guide instead of a footnote: it is insurance with a precisely stated scope, from makers who publish the scope.
The kits
Prices are the vendors' listed street prices, checked October 2026 — verify before you buy.
| Kit | Material and design | Pattern | Kit torque |
|---|---|---|---|
| VTT Crank Bolt Capture (~$127) | CNC aircraft-grade aluminum, black anodized, about 1.3 oz | Application-specific damper-bolt pattern; ships with 6-8 bolts and washers in spline-lock kits | 40 ft-lb (~54 Nm), provided bolts and washers |
| Kies Crank Bolt Lock ($119-139) | Billet 6061 aluminum, black or blue anodized; 32 mm hex machined in; single steel washer (their answer to 6-8 small washers — pressure distribution, easier install); 12.9 bolts | 8-bolt N55/S55, 6-bolt N54 (some N54s are 8-bolt — inspect) | 40 Nm per bolt, star pattern, medium-strength threadlocker recommended |
| Budget tier (BAVMODS-class, ~$100) | Varies — read the sheet | Varies | Per kit |
The Kies 32 mm hex detail is more than a convenience: it is the factory-sized socket on the front of the engine, so future hand-rotation by the crank bolt method works without removing the lock. The VTT counterpart's design brief is weight and pattern fidelity — at roughly 1.3 ounces it is invisible to the damper's balance.
One hard compatibility line from VTT: their capture fits the factory crank bolt only and will not fit an aftermarket bolt. If your build runs a non-factory bolt, that capture is off the list until the bolt changes.
When to install it: the clocking problem
A capture has to land with its holes over both the damper fasteners and the crank bolt head — and the bolt head's final position is whatever the angle stage left it at. That is the clocking problem, and it is why the honest answer to "when?" is during the hub or damper job:
- The vendor's splined-hub sequence builds clocking in from the start: mark one damper bolt hole during the angle stage and line the bolt head up deliberately, so the capture drops on at the end with no forcing.
- Their capture page says it plainly: on some vehicles the holes will not align at the existing torque position — do not force the capture into place; a new factory crank bolt may be required so it can be torqued and clocked correctly.
- The Kies note is the same truth from the other side: in rare occurrences the crank bolt may need to be slightly stretched for the lock to fit.
Read those together and the law falls out: never chase clocking by adding angle to a bolt that already took its stretch. The central bolt is single-use, torque-plus-angle — if the head landed in the wrong clock, the fix is a fresh bolt done properly with clocking planned, not a quarter-turn "adjustment" of a yielded fastener. That is why a capture onto an undisturbed engine is sometimes a five-minute fit and sometimes a redo-the-bolt job — and why everyone pairs it with work that has the bolt out anyway.
The install sequence
Vendor instructions, paraphrased. The engine pages carry the factory damper and hub procedures this rides on.
- Do the factory job first. Whatever brought you here — damper R&R, chain job, hub conversion — finish it to the factory spec: fresh central bolt, 100 Nm plus the full angle (360° N54, 270° N55/S55), torque tracked and the head's final clock known.
- Plan the clock during the angle stage, not after. Mark the bolt head and one damper fastener hole before stretching; aim the head's landing at a position the capture accepts. This is the one step that costs nothing and saves the redo.
- Count the pattern. Six or eight damper fasteners — physically confirm against the capture before it goes anywhere near the car (the N54 8-bolt wrinkle is real).
- Trial-fit the hardware. The Kies instruction: ensure the provided bolts thread into the crank hub with ease before any final torque. A bolt that binds is a thread problem to fix now, not at 40 Nm.
- Mount the capture over the bolt head, washer(s) per the kit's design (VTT: provided bolts and washers; Kies: their single washer), and bring the bolts down evenly.
- Torque per the kit sheet — VTT: 40 ft-lb (about 54 Nm); Kies: 40 Nm per bolt, star pattern, medium-strength threadlocker where their sheet recommends it. The two specs differ on purpose; the sheet in your box is the authority.
- No force, ever. If the capture's holes and the bolt head disagree, stop — the fix is clocking (a new bolt, properly stretched), not the hammer.
- Function check. With a Kies lock: the 32 mm hex should accept the factory socket and turn the engine cleanly. Any capture: no contact with the damper face beyond the designed register, no vibration-path edges, all bolts at spec.
| Fastener | Spec | Torque |
|---|---|---|
Central bolt, N54 (M16 x 80) | Replace; single-use; lightly oiled | 100 Nm + 360° |
Central bolt, N55/S55 (M18 x 108) | Replace; single-use; lightly oiled | 100 Nm + 270° |
N54 damper-to-hub screws (M8 x 16) | Factory spec | 35 Nm |
| Capture bolts | Per kit — VTT 40 ft-lb / Kies 40 Nm star + threadlocker | Per the kit sheet |
The gotchas
- The quarter-turn temptation. A clocked-wrong bolt head begging for "just a little more angle" is the single worst move available — it is re-yielding a yielded fastener. New bolt, full procedure, planned clock.
- Aftermarket bolt incompatibility. VTT states their capture is factory-bolt-only. A captured aftermarket bolt that does not seat the plate properly is worse than no plate — it looks protected and isn't.
- The pattern mismatch. Ordering by engine alone catches out the 8-bolt N54s. One look at the damper before ordering closes the risk.
- Threadlocker discipline. Where the sheet calls for it, it is doing real work — these are small bolts in a vibration environment doing a safety job.
- The false-sense risk. The capture is the cheapest part of the crankhub story precisely because it covers the cheapest failure path. A tuned car with a capture and a tired friction stack has bought half an insurance policy — the conversions guide's decision tree is the honest next read.
The verify checklist
- Capture pattern matches the damper — counted, not assumed.
- Bolt head clocked under a capture hole by design, not by force.
- Kit hardware threads freely before final torque; washer(s) seated per the kit diagram.
- Bolts at the kit's spec — 40 ft-lb or 40 Nm — star pattern, threadlocker where specified.
- No forcing at any stage; a misfit means clocking work, not persuasion.
- Function check passed — socket engagement, clean rotation, no interference.
- The bolt underneath is fresh, at full factory torque-plus-angle — a capture on an old stretched bolt is locking the barn after the horse.
Where this sits in the plan
The capture pairs with everything: on a stock hub it is the cheap tier; with a pinned conversion one kit maker recommends it outright; with a splined hub the vendor treats it as required. The install moment belongs to the hub or damper job — the engine pages carry those procedures, the splined and pinned guides carry the conversions, and the while-you're-in-there arithmetic (seal, chain, refresh, head-stud adjacency) is the same on every path. Every factory number on this page traces to the factory document ids listed in the sources; every kit claim is the vendor's own documentation, current as of October 2026.
References — the research shelf
- VTT S55/N55 Crank Bolt Capture product page (design, factory-bolt-only rule, clocking and limitation text)
- Kies Motorsports — Crank Bolt Lock product page (32 mm hex, single washer, 6/8-bolt, 40 Nm star spec)
- VTT Spline Lock install guide (PDF — capture install at 40 ft-lb and clock-ahead marking)
- JG Media — Kies crank seal guard and bolt lock install video
- Turner Motorsport — VTT S55 Crank Bolt Capture listing (price cross-check)
- BAVMODS — N55/S55 crank hub bolt capture kit (the budget tier)
Does a crank bolt capture stop the crankhub from slipping?
No — and the vendors say so themselves. The capture mechanically prevents the central bolt from rotating back, which protects the clamp-load path. It does nothing for the other failure path: a torque spike that overloads the friction stack itself. One maker's product page states it is still possible to spin a crank hub with the lock fitted; the other says outright it is not a complete repair for every failure mode. It is insurance against bolt back-off, not a mechanical-lock conversion.
Can I install a capture without taking the hub off?
Sometimes — but the clocking decides. The capture's holes must line up with the bolt head and the damper fasteners at whatever angle the factory angle stage happened to stop. If they don't, the vendor's answer is not force: it is a new factory crank bolt, torqued and clocked so the head lands under a capture hole. On an engine where the bolt was just done, that means redoing the bolt; riding the hub or damper job is why most captures go on during that work.
What torque do the capture's own bolts take?
Per kit, and the two main kits differ: the VTT capture bolts to the damper at 40 ft-lb (about 54 Nm) with the provided bolts and washers; the Kies Bolt Lock specs 40 Nm per bolt in a star pattern with medium-strength threadlocker recommended. Forty foot-pounds and forty newton-meters are not the same number — follow the sheet that shipped with your hardware, not the forum's average of the two.
Six bolts or eight?
Count before you order. The Kies lock ships an 8-bolt version for N55 and S55 and a 6-bolt for the N54 — and their own note is that some N54s carry an 8-bolt hub, so physically inspect your damper's bolt pattern on every N54. VTT's capture is application-specific to the damper pattern and ships 6-8 bolts depending on the kit configuration.
Capture on a stock hub, or only with a conversion?
On a stock hub it is the cheap tier of the whole aftermarket — a fresh factory bolt at full spec plus a capture addresses the bolt-back-off path for three figures. One kit maker explicitly recommends pairing their lock with a 4-pin conversion; the splined-hub vendor treats the capture as a required companion to their hub. The decision layer — which path for which car — is the conversions guide's job.
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