cranks, pilot bearings and auto trannies

Mon, 29 Jul 2002 08:39:23 +0200

The auto cars use a bushing in the crank, the manuals have a bearing
in the crank or the flywheel depending on whether they are the turbo
or non-turbo motors. Turbos have them in the crank. I learnt all
this recently.

If you're putting in a manual transmission then you'll need to remove
the bushing and fit the proper pilot bearing. There are 2 pilot bearings,
both have the same outer diameter (24mm if I recall correctly),
but have different lengths and inner diameters. Select the one which
has the inner diameter matching the diameter of the input shaft on
the manual transmission.

To remove the bushing requires a puller than can go through a opening
of about 15mm and pull a bearing on its inner race. The exact tool
is available over in the USA for around $25, but I can't recall the

I didn't have access to that over here in South Africa and settled
for using my own contraption. The bushing has an ID of 15mm and it
is a press-fit item. My quick-fix had the following items:

 1. M16 thread tap
 2. matching tap handle
 3. M16x20cm bolt (or longest M16 bolt you can get)

Tap the bushing with the M16 tap and handle, try and go as straight
as possible. Remove the tap, separate handle from tap and then push
the M16 bolt through the tap handle and then fit the bolt tightly
into the bushing. Now use the handle as a sliding hammer along the
length of the bolt. The handle with hit the back of the bolt head
hence acting like a sliding hammer. It took a few seconds to remove
after many attempts at other methods.

M16 tap and handle was on loan from a ship engineering shop, but
should cost about $10-$15 (not sure). 15-20cm long M16 bolt was $2.

I haven't fitted my pilot bearing yet, but I understand it has to
be installed in the crank so that it either protrudes 5mm or is seated
in 5mm. Anyone got a quick answer to that? Bentley says to install
until a=5mm, but they never mark what "a" is. :)