Thust bearings and surfaces

[PhyrraM]

There are very few things 'on the net' I take at face value. There are, however, a few people that have earned my trust. Such as Matt, Matt, Vikash and others on other forums. I read that early phase 2 EJ25 cranks were supposedly machined with both #3 and #5 thrust surfaces.

i picked up a crank from an '01 EJ251. It appears to be machined for both thrusts, but the #3 thrust (never used) has machining marks. They *feel* smooth, I can't catch a nail on them. However, the #5 'used' thrust is virtually a mirror.

"used" #5 journal


"Fresh" #3 journal


My question is...Was the #5 journal polished from the use of the motor? Did it start out looking like #3?

Or....Was #3 left unfinished by the factory and I need to have it polished before installing it.

*NOTE*, I have not properly checked endplay yet, but a quick check with a feeler it seems to be in spec.

[log1call]

Thrusts normaly have the same finish as the crank journals.

That thrust looks far too rough for a bearing to run on.
If you polish those marks out you are going to need oversize thrusts.

I would suspect it was never intended as a thrust.

[GodSquadMandrake]

The best picture I have of my crank doesn't show it very well.



But that's an EJ22T crank and it only has one thrust bearing on the crank which is #3.

The picture is bad but it doesn't look nearly as scored as yours is because you can actually see a reflection in it.

[entirelyturbo]

It's possible that Subaru essentially just took the Phase I crank design and started machining #5 thrust surfaces in them for Phase II, thus leaving an unused thrust surface on #3.

I honestly am not 100% sure what the question is, but just so you know, I've got a couple years at a Subaru dealership, with access to all Subaru official documents and specifications, and I can definitively say that the Phase II engines have a thrust bearing in the #5 position and not the #3 position. So, if you want to rebuild the motor according to Subaru specifications, put the thrust bearing at #5 and a regular bearing at #3.

[PhyrraM]

I have no doubt about the factory thrust positions. I'm trying to work around them.

My goal is simply to build a 'classic' 2.35 stroker. I am trying to use components I already have. The main thing I have is a very nice set of Pauter rods sized for the phase II 52mm journals. I haven't had success in finding affordable phase I rods to replace them with.

I am trying to find a *supposed* phase II (52mm) crank that is factory machined for both #3 and #5 thrusts. I would chalk it up to internet rumor, but the crank was referenced by people whose info is normally trustworthy.

Either way, I'm looking for a machine shop I trust that can machine one of my blocks for a proper phase II thrust location.