Adjusting Pinion And Ring Gear


Careful adjustment of the drive pinion and ring gear is important to guarantee a long service life and quiet running for the final drive. This is why drive pinions and ring gears are matched during production and checked on special testing machines for the most favorable surface appearance and low noise levels in both directions of rotation. The position of quietest running is determined by moving the drive pinion in an axial direction, keeping the ring gear within specified backlash tolerances.

The deviation "x" from the master gaube "Ro" is measured and inscribed on the outside periphery of the ring gear belonging to a pinion/ring gear set supplied as a spare part. Each set (drive pinion and ring gear) may only be replaced together.


Service Sets

1 - Code "K 935" means pinion/ring gear set with

Klingelnberg teeth and 9 : 35 ratio. Number always has 3 digits.

2 — Pair code 312 of pinion/ring gear set. Number always has 3 digits.

3 — Deviation "r" in reference to master gauge of special testing machines used in production. Deviation "x" is always given in 1/100 mm and always has two digits. For example: "25" means "x" = 0.25 mm. Other letters or digits concern manufacturing and material batches.

Ro — Length of master gauge used in special testing machine.

Standard Sets Important!

In production the location of the drive pinion is given by distance Po (center of ring gear to back of pinion head). Deviation "r" on the ring gear and the pair code are omitted. Because deviation "x" is not given, the installed position of the drive pinion must be measured before removing same, when replacing parts which have direct influence on the installed position of the drive pinion.

X — This data not required in production. E — Actual distance between ring gear shaft and face of pinion at point of quietest running for this set.

Recommended Sequence of Adjusting Pinion and Ring Gear

Porsche 911 Adjusting Ring Pinion Gear

51 = Shim for ring gear The goal of adjustments is to relocate the point

52 = Shim for ring gear °Pt'ma' Qu'et running as was determined in the

53 = Shim for pinion

54 = Shim for pinion Perfect results require absolute care and cleanliness special testing machine during production.

Perfect results require absolute care and cle during all assembly and measuring operations.

When it becomes necessary to adjust the pinion and ring gear, it would be in the interest of economical procedures to keep to the following sequence.

1 — Determine the total shim thickness "Stot"

(Si plus S2) for the specified pre-load of tapered roller bearing/differential.

2 — Determine the total shim thickness "Stot"

(S3 plus S4) for the specified pre-load of tapered roller bearing/drive pinion.

3 — Divide total shim thickness "Stot" in S3 and S4

that the distance from center of ring gear to face of drive pinion is equal to distance HE" determined during production.

4 - Divide total shim thickness "Stot" in Si and S2

so that there is the specified amount of backlash between the ring gear and pinion.

Adjustment Survey

The pinion and ring gear only have to be adjusted when repairs on the final drive require the replacement of parts having direct influence on the adjustment. Refer to the following table to avoid unnecessary adjustments!

Replaced Part

Ring Gear (Sx +S2)



Pinion only shim "S4"

Transmission case

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