(http://www.mazdatrix.com/faq/pulley.htm)
ANYONE changing a front pulley, or loosening
the front eccentric shaft bolt for ANY reason!, needs to be aware of what
can go wrong with the Torrington thrust bearings inside the front cover/front of
engine!!
Before we wade through this FAQ, the way to prevent the problem from
happening in the first place is to, (BEFORE! you loosen the bolt):
1) If the engine is in the car (this
DOES NOT APPLY for 93-95's) do something to wedge the clutch pedal down -- meaning a 2x4 or
something like it, holding the pedal down and wedged against steering wheel or
front of the seat.
2) If the engine is out of the car, set it with the flywheel down,
front pulley up, the whole time you are working on the front of the engine. Do
not roll the engine horizontal until the front bolt is tightened.
3) For 93-95's you need to do something to wedge the flywheel forward
- easiest we have done is a small piece of wood up through the inspection plate
on the bottom of the bell housing. With the wood between the pressure plate and
the bell housing. Do something to hold it there, because if you rotate the
engine while trying to get the bolt loose, the wood will fall out.
What any of the above steps will do is to hold the rear Torrington
bearing in place against the thrust plate - keeping it from dropping out of
place if the spacer moves forward.
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This is what the front "stack"
looks like outside of an engine. The bolts shown hold the thrust plate and
front stationary gear to the front side housing. |
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With most of the pieces out of
the way, you can see where the front torrington bearing is -- the other
bearing is between the thrust plate and the front of the front gear. |
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Side view of the "stack" with the
gear not there. For those not familiar with this assembly - it is what is
setting the "end-float" of the eccentric. With the thrust plate and front
gear bolted to the front side housing, and pulley tightened down, the
"stack" is solid to the eccentric --EXCEPT the torrington bearings, which
are floating "loose". |
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Here is the "stack" spread apart -
this "group" order (front to rear) is: front counterweight, thin thrust
washer (which also actually "floats"), bearing, thrust plate, bearing,
thicker thrust washer, with spacer under the plate and bearings, all goes up
against the shoulder on the eccentric. |
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This shows the rear bearing
sitting up on the spacer and against the rear thrust washer - like it
should. This spacer is what the stack clamps against, and is what comes in
different thicknesses so end float can be adjusted. |
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Here is the "bad" thing that can
happen when that front bolt is loosened - there is nothing to hold the
spacer in place, and it gets pulled forward when the pulley is removed.
Since the bearing can't also go forward (it's against the thrust plate), it
simply drops down behind the spacer. |
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This shows the bearing dropped
down out of place, between the thrust plate and the rear thrust washer. |
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Bearing dropped down in relation
to the spacer. |
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You can see what happens to the
bearing when the front is reassembled, and the bolt tightened! The spacer
smashes the bearing. |
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This bearing is supposed to be
FLAT! |
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Here comes the rest of the
damage--
The spacer can actually be dented by the needles of the
torrington bearings. |
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The thrust plate gets destroyed. |
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This was an extreme case -
normally the thrust washer is really chewed up. This was even split! |
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And the resulting destruction of
the thrust surface of the front stationary gear. |
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If you think you have
dropped the bearing, you are welcome to try anything you want to get it back
up in place, but we strongly suggest it will be faster to just bite the
bullet, and pull the front cover off.
If you think your engine may already have the bearing down, and
the engine has been run, first check to see if you have ANY end float. This
is the amount the eccentric / pulley / flywheel will move front to back.
Spec is .0015" to .0028" - not much at all, but some. If you have absolutely
NO float, you have a problem.
All of the damage CAN be repaired with the engine in the car, and
the front cover off. The front gear can even be replaced (just DO NOT
rotate the eccentric AT ALL while the gear is out. |
Parts list if you
are going to pull your front cover: Front cover gasket
Front cover "O-ring
Oil pan gasket Water pump housing to engine gasket At least one Torrington bearing (assuming the front bolt has been tightened)
More parts we recommend, or you may need if it has
been run: The other Torrington bearing Front seal Thrust
washers) Thrust Plate
Hopefully you will not need a front stationary gear.
If the spacer has been damaged, try to salvage it with a file or
something. That way (assuming end float was previously set correctly) you
will not have to re-set end float by trying various thicknesses of spacers. |
This site is meant to give information related to the 1993
(o)Mazda RX-7 Twin Turbo. Anything from rotary engines to wiring diagrams and turbo upgrades to tuning info, this site has it all! efini 93 rx7 13b anfini Turbo RX-7 Turbo RX7 turbo rx7 rx7tt rx-7tt As well as the Rotary Engine Pickup Truck aka REPU repu
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