Engine · 993-ENG-CHAIN-CASE-LID-TI-F0-0001
Left chain case lid 964 105 107 01, Ti-6Al-4V variant
ConceptFunctional part
Bolted, oil-tight left lid of the chain case, factory plate 103-05 position 15, paired with gasket 964 105 181 01. Remanufacture in machined Ti-6Al-4V explicitly requested. The original part is **cast magnesium**, whose failure mode is corrosion of the sealing faces: that is where titanium brings something, not on mass. Against magnesium, titanium is 2.45 times denser and loses both plate-bending trade-offs, strength included. One serious obstacle remains: the titanium/magnesium galvanic couple is the least favorable in the grid.
The design
- Vehicle
- Porsche 993, 1994–1998
- Variants
- 993 split by variant to confirm
- Porsche part numbers
- 964 105 107 01, 964 105 181 01
- Category
- Engine timing chain case lid
- Geometry basis
- Estimated
- Preferred process
- CNC machining
- Material
- Ti-6Al-4V Grade 5, plate — deliberate choice; 6061 billet aluminum is the market's answer
- Material standard
- ASTM B265 for the plate, to be contracted
Known limits
- The original part is cast magnesium, not aluminum: any mass comparison made against aluminum was comparing with the replacement product, not the original.
- Against magnesium, titanium loses both plate-bending indices, strength included: it will not be lighter, whatever thickness is chosen.
- No dimension is measured: outline, thickness, hole spacings, holes, gasket face and centering are unknown.
- Neither commercial reproducer publishes a dimension: the dimensions cannot be found online; they are obtained by buying the part or its gasket.
- The computed expansion margin, +0.056 mm, rests on an extreme hole spacing of 100 mm and an 8.4 mm hole for M8 screws, both hypothetical.
- The internal clearance to the chain and tensioner is not measured.
- Titanium makes the part 64% heavier at equal geometry; it is a deliberate material choice, not a gain.
- The part retains oil: a leak on an air-cooled engine has hot neighbors, hence the `functional` class and not `non_critical`.
- No leak test, thermal cycling or repeated removal-refitting.
- The manual's tightening torque, 9.7 Nm, places the fasteners at M6: the expansion margin computed on an M8 assumption must be redone once the hole is known.
- The titanium/magnesium galvanic couple is not resolved and could shift corrosion from the lid to the case.
Post-processing it would need
- Facing of the gasket plane, flatness to be defined after measurement
- Edge breaking
- Bead blasting or titanium anodizing depending on the intended finish
- Anti-seize paste on fasteners, insulating washers if direct metal contact
What a supplier would have to provide
- Material certificate for the plate
- Flatness and surface finish held on the gasket plane
- Dimensional inspection of the outline, hole spacings and holes
Titanium route
- Alloy
- Ti-6Al-4V Grade 5
- Heat treatment
- none: part machined from plate supplied in the annealed condition
- Hot isostatic pressing
- Not applicable
- Gasket plane flatness
- Hole spacings
- Thickness
Sources
- 993 factory catalogue, plate 103-05 Chain case · read
Position 15 `lid` 964 105 107 01, paired with the position 16 `gasket` 964 105 181 01. The catalogue identifies; it does not dimension.
- Commercial reproducers of the lid: LN Engineering and Auto-Service Schefter · read
Confirms that 964 105 107 01 is the left lid, paired with gasket 964 105 181 01, and that the part is reproduced by machining from solid. Both reproducers use aluminum. Neither publishes a dimension.