I started installing the thrust washers, bearings and all to check the front
end play. But I don't remember having such a big space in between the plate
and the parts under it. I took a sequence of photos of the individual parts.
Does this look normal?

Thanks

Jay


I am no 20B expert by a long shot.
Do you have the 3rd gen RX7 engine manual?

Looks like the purple spacer is too thin. They come in different thicknesses.

Down load the 1991-93 shop manual from here and read up on the
thrust bearing installation. It should be the same as the 3 rotor.

http://foxed.ca/foxed/index.php?page=rx7manual

  From the thinnest to the thickest is only .12" but that
looks like more than .12". One side of the spacer is
chamfered are you sure that chamfer is towards
the engine?

-------------------------------

I think I see the problem.

If that is a new needle bearing it may not be a 3rd gen.
The 3rd gen bearings are larger in diameter. I suspect
the 20B uses the 3rd gen needle bearings. That spacer
should fit inside the needle bearing I think.

It could be the wrong 2nd gen thrust plate as well.


Paul Lamar

That is not the piece that goes there. The actual spacer is a segment of a
tube. It must fit through the thrust plate and the centers of the thrust
bearings. The length of the spacer tube controls the end play. Usually .0025"
to .0035" But I don't have any 20B data so check on that. Those numbers
should be enough. It is just to be sure that the thrust bearings are not ever
preloaded in any way, and a bit extra to prevent pinching the bearing with
crank flex, should you scream the engine.

That fat looking spacer may go on last to adjust the position of the front
pulley. The last time I saw one was on an RX-2. Once Mazda could machine two
pulleys the same height or buy them, the spacer vanished.  It looks normal
up to that point. You need to find the correct spacer.

It goes:
 Hardend thick washer with the chamfer to the center of the engine to allow
for the radius on the crank nose. Then a bearing with the spacer in its
center to keep it from falling behind the end of the spacer. Then the thrust
plate with two bolts just snug..

 Then the second bearing.

Then the thin hardedned washer that fits into the back side of the front
counterweight.

Then the counterweight. (You glue the thin thrust washer to the
counterweight with a dab of grease).

Then the spiral gear drive for the distributor or crank angle sensor..

Then that thick looking thing if required to adjust pulley depth or if not
just the front pully.

Be sure the spacer is through the center of the first bearing.

Install the big bolt and washer and torque the front pulley to spec. (70 to
115) Tighter makes the nose stiffer. Then check the end play with a dial
indicater and magnetic base.

You can also do the whole thing off of the engine if the crank is still
out.

All of the thrust measurement is controlled by the thickness of the spacer
tube. Nothing else.

They are available in different lengths. If yours is too long you may lap
it in order to shorten it.

Shorter spacer = less end play. Longer spacer = more end play .

The spacer tube that came out of the engine is probably ideal.

Once you have the correct end play, remove everything down to the thrust
plate and bolt the plate down with all of the bolts. Safety wire the bolts
with the finished ends inboard to avoid the counerweight touching them. No lock
washers. Those thing only bit into the shitty bolt heads and make swarf to
fall of into the bearings. Use hard washers the same thickness.

The bolts are crap, but that is fine. the threads in the casting are weak.
No locktite as the threads may come out with the bolt, or the bolt may break
off. Just to minimum torque and wire them.

Lynn E. Hanover

Thank you everyone for taking the time to respond. After posting the
question I watched my rebuild video on this part several times and finally
realized the thrust bearing should slide over the outside of the spacer,
mine don't. These are new made in Japan bearings I got from Mazdatrix that
fit all models through 1992. I got an email from them today, while I was at
work, informing me that the 20B uses 93' - 95' bearings ect. For some reason
I was thinking this was a second gen engine.
So I simply have the wrong bearings, which are smaller than the originals.
I just finished ordering the proper ones.

If anyone is interested I'll sell the pair of P/N 0813-11-505B bearings,
brand new, at a discount to what I paid.

Lynn,
I replaced all of the bolts with new and had planned on using split lock
washers since that's what was there originally. Also there was no safety
wire. I'll get some bolts with holes in the heads and new flat washers. I
presume it'd be a good idea to do the same with the rear stationary gear?


Jay