Petrol engines spigot-shaft bearing

Introduction

The spigot shaft bearing is the common name for a (usually needle) bearing (or plain bush ) in the clutch end of the crankshaft that helps to align and support the 'spigot' or gearbox input shaft (sometimes called the 1st motion shaft)

VW T25(UK)/T3 (Euro) utilise needle rollers beearings as their input shafts project a considerable distance from the first(closest) of the their gearbox support bearings.

A characteristic of a worn spigot shaft bearing is a rattling from that bellhousing area when the engine is idling in neutral and the clutch engaged... depressing the clucth pedal removes drive to the input shaft and rattling/knocking may cease, a fairly accepted diagnosis.

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Alt Engines and (missing) spigot shaft bearings

NB. When replacing your T25 engine with another Alt Eng. such as a VW in-line 4 (Golf 1800 etc) it is wise to check whether it actually has a spigot-shaft bearing in the crankshaft recess.

Many other engines do not (or have a plain bush) as their 1st motion shaft /input shaft are short and fully cantilevered from the gearbox bearings.
This requires one to be fitted to suit the T25 g.box spigot.

This also applies to Alt Diesel engines.

The result of overlooking this can do a lot of damage to the input side of the gearbox, such as the oil seal, bearing and oil thrower, and annoys the bejesus out of Aidan to boot :)

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How to replace a spigot shaft bearing

Aidan: So faced with flywheel

you need to undo the 5 bolts holding it on - it helps to have an impact gun, but failing that a 2 foot bar and another long bar or a flywheel locking tool to hold the flywheel whilst you undo them 10mm Hex

leaves you with

then armed with your puller or slide hammer

fit into bearing and tighten then fit slide hammer

and start to pull it

till it comes out :ok

leaving an empty space in the flywheel with a stop behind

this shows the diesel spigot bearing on the left and petrol on right, the flat face with the writing on faces the gearbox the curved end faces the engine when fitted

as you can see the receiving hole in the crank is 21mm

as is the bearing shell outer diameter

and the inner dimension is 15mm ish - to match the spigot end of the input shaft which will be just under 15mm (like 14.97mm)

and the felt washer on the petrol engine fits in the recess on the back of the flywheel and the sealing o ring sits in the groove, just visible in the picture

Replace the 'O' ring, the washer and the spigot bearing and reassemble - flywheel bolts need to be tight but VW tightening spec is scary tight as previously noted - 60Nm (44ftlb) plus an added 90degrees - you probably won't get them that tight so use a very little threadlock

Lube the new bearing with high temp grease :ok

Links

Here is a link to a forum thread on this, the 2nd of each pair of links hopefully still working once the topic has been moved to the 80-90 Tech Archive in due course (don't ask!)

itchyfeet: thread
Current forum
Future Archive

nickthefish: thread
Current forum
Current forum

From the diesel spigot-bearing topic

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Other

More about spigotty things..