AJatx

iTrader: (1)

Just curious if eccentric shafts between generations and AT/MT are the same or different?

I'd imagine the eccentric shaft between 2nd gen and 3rd gen may be interchangeable.

The eccentric shaft I recently acquired has a smaller diameter tapered hole where the pilot bearing is installed. I checked some S5, S4, and FD eccentric shafts and all of the parts I tested can fit the S4 pilot bearing I'm using.

Just wondering if I should bore out this eccentric shaft since the motor is closed up or if I should rebuild again with a different eccentric shaft.
A slight misalignment on the bore could cause some issues with the transmission shaft or engine.

I have the picture of the old pilot bearing. You'll notice the deformed lip and slight conical shape.
The other picture shows the new pilot bearing in this eccentric shaft. It only goes in half way. There is nothing "stuck" in the e-shaft passage as I have already cleaned it up with a little 240 grit sandpaper.

J

AJatx

iTrader: (1)

Here is a picture of the new pilot bearing in the old S5 eccentric shaft.
This shaft is no longer good since the front bearing failed on this part.

alwayssideways

i had the same problem. I ended up drilling the bore of the hole to match the pilot bearing

Carzy Driver

did you try lubing it up some? are you installing it with the correct side going in, rounded edge first?

TII '87

the way I got it in was to heat up the shaft and to freeze the bearing

after that i lubed it and got it in with some effort

but I admit it was a bitch to get in there!!!

AJatx

iTrader: (1)

Yes, I did that to the first pilot bearing.
Both ends are identical, rounded on edge.
It's the pilot bearing, not oil seal. Oil seal is unidirection.

AJatx

iTrader: (1)

It'll be the first time I have to freeze the pilot bearing and heat the eccentric shaft to install it. I've never encountered this fitment issue until this eccentric shaft. I've done FC and FD replacements (pretty much the same thing).

But, I'll give it a try.

AJatx

iTrader: (1)

The first new pilot bearing that I tried installing had a compressed outer diameter which popped the needles out of the race.

I always check the "needle" bearings after installation and the previous pilot bearing had seized bearings, at least the 5 or so that stayed in the race.

So I may need to bore out the eccentric shaft a wee bit.

Carzy Driver

where are you getting your bearings? who's the maker of them?

1SxyRXy

go to autozone and rent a damn pilot bearing remover. they probably wont know what it is but they have one. you also have to hammer the new one in

AJatx

iTrader: (1)

It's a Mazda OEM part. It's the same part being used since the 80's.

AJatx

iTrader: (1)

I'm not having issues REMOVING the pilot bearing.
It's an issue with fitment. If you "hammer" or press the bearing in the eccentric shaft, the bearing becomes "pinched" and the needles bind to the race or pop out.

So, the transmission shaft has a very good chance of binding to this pilot bearing and failing prematurely.

AJatx

iTrader: (1)

In case it's hard to see in the picture, the new pilot bearing fits 90% or so into the old eccentric shaft. The current eccentric shaft only allows 50% of the pilot bearing to fit.

I already ruined a bearing thinking it just needed to be "forced" or "hammered" into the eccentric shaft. After digging up a thread I wrote on making a pilot bearing installation SST when I installed a twin plate clutch, I recalled that the bearing should fit most of the way into the eccentric shaft. You "hammer" or press in the rest of the pilot bearing and then the oil seal (which requires correct orientation).

It's the first time I've encountered this issue after rebuilding engines/replacing and upgrading clutches on FC's and FD's.

So far, alwayssideways is the only person who had a similar experience.