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     901, 5-speed gearbox


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     Shift Housing


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 Blue Printing the 915 Shift Housing

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Objective:
To increase shifting accuracy by reducing tolerances in the factory shift housing

Degree of Difficulty (scale of 1-10) = 3

While the Gate Shift kit provides more accurate gear selection, there are additional modifications to incrementally increase the "feel" of the shifter and thus provide more accurate shifting. These additional shifter modifications are as follows:

-

Permanently join the multi-piece shift lever to prevent separation and loss of gearbox control

See B below

-

Adjust the shift lever-to-fork clearance. This reduces friction when moving the shift lever in the fore-aft direction

See C below

-

Adjust the shift housing-to-fork clearance. This reduces friction when moving the shift lever in the left-right direction. Applies to post-'77 shift housings only

See D below


Fig. 1. Shift housing, 1973-77 (click to enlarge)

Procedure

A.

Remove Shift Housing

Fig. 2. Threaded pin and locknut, 1977-86

1.

Loosen the threaded pin locknut on the front of the shift housing (see Fig. 2).
('77- '86 shift housing only).

Note:
To facilitate removal, loosen the lock nut (22mm socket) with the shift housing installed in the vehicle.

2.

Remove the shift housing from the car, then disassemble, clean and inspect parts. Replace worn parts if needed.

Note:
Leave fork installed (Fig. 1). If replacement necessary, use a pin punch to remove the fork pivot(s) (spring pin).

CAUTION:

When disassembling the shift housing, be aware there are two springs under the carrier plate (see Fig. 1). To prevent personal injury, disassemble the shift housing using a bench vise (or equivalent) to slowly release spring tension

B.

Modify Shift Lever
Permanently join the lower and upper shift lever to prevent the shift lever from separating.

Note:
The upper and lower lever sections are factory-joined with an epoxy-glue.

Tack weld both sections of the shift lever as shown (Fig. 3).
MIG or TIG welding preferred.

Remove the ball socket before welding.

Fig. 3. Tack welds join lever sections

C.

Adjust Shift Lever-to-Fork Clearance
Decrease friction by reducing the interference fit between the shift lever and the fork (the outer diameter of the lever is larger than the space in the fork).

Note:
Use a belt-type sander to reduce the OD of the shift lever where it contacts the fork.

Go here for more info.

Fig. 4. Resized lever OD. Click here for more info

D.

Adjust Fork-to-Shift Housing Clearance
'77 - '86 shift housing only (Fig. 5)

Adjust fork tension.

Adjust tension so the fork can rotate by hand with a slight amount of drag.

Note:
The threaded pin determines the lateral (side-to-side) play of the shift lever. When using the Gate Shift kit, reduce as much friction as possible.

Excessive play may cause the shift lever to rattle/vibrate.

To increase the adjustment range, remove the M8 spring washer (Fig. 5) and replace with a flat washer. Lubricate all friction areas before reassembly. Apply anti-seize lube to the lock nut threads. Do not overtighten the lock nut.

Fig. 5. Fork assembly w/assembled shift housing, 1977-86

E.

Reassemble Shift Housing
Relube all friction points with moly-based grease, water-proof grease or equivalent.

For best performance, inspect the following parts, then replace if needed:

Part name

Part no.
Qty.

Bearing bush

914 424 224 00
1

Ball socket

911 424 139 00
1

Shift coupler bushing

695 424 223 00
2

The above replacement parts are available from Porsche or most aftermarket parts suppliers.

Fig. 6, Blue-printed shift housing w/Gate Shift kit







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