As sometimes happens during assy....I found something not quite right:

I've chosen a set of Eagle rods (CRS5137S3D) for my engine. The bearing crush is not acceptable. There was deformation of the bearing when approaching 25 ft/lbs.

What I need to do is ascertain whether

a) The rods are not machined properly (they mic good; dial bore gauge is okay)

b) The bearings are not the right size....I think the PN is correct (12108AA730 for STD rod bearings?)

or

c) The crank pins are a different size from the EJ205 to EJ257

My crank pins are 2.046". The rod big end bore is 2.165 (the stock STi rod is 2.166"). The STi manual states that a STD bearing thickness is .0587-.0591....mine measure .061. Interestingly enough, the WRX FSM lists the EJ205 (DOHC section) as having crank pins measuring 1.8891 (STD). Can someone confirm this? The WRX SOHC section lists crank pins of 2.046" which is what I have. Maybe I've goofed....but that's why you check, check, and recheck.

Thanks for the help!
Steve

b) The bearings are not the right size....I think the PN is correct for a EJ257 STD rod bearing (12108AA730)???

or

c) The crank pins are a different size from the EJ205 to EJ257?

My crank pins are 2.046". The rod big end bore is 2.165 (the stock STi rod is 2.166"). Interestingly enough, the WRX FSM lists the EJ205 (DOHC section) as having crank pins measuring 1.8891 (STD). Can someone confirm this? The WRX SOHC section lists crank pins of 2.046" which is what I have. Maybe I've goofed....but that's why you check, check, and recheck.

Thanks for the help!
Steve


Bump for help, please. :)

Crank pins? You mean the journals on the crank for the rods? IIRC, they should be 52mm, about 2.0472"

Now the 1.8891" dimension sounds a lot like a phase 1 motor's crank (pre 1999, usually). Phase 1 motors had crank journal sizes of 48mm, or 1.8897".

Regardless, if they're both USDM motors (WRX/STI) then I would say they all should be 52mm crank journals, phase 2 cranks. IIRC, the crank we had pulled out of RiftsWRX's original motor (2002, EJ205) was a phase 2 crank, 52mm crank journals.


You should be able to measure the diameter of the bearings, approximately, by measuring from inside to inside of the tips on one half. What do those measure out to?

Crank pins? You mean the journals on the crank for the rods? IIRC, they should be 52mm, about 2.0472"

Yes, the rod journals.



Now the 1.8891" dimension sounds a lot like a phase 1 motor's crank (pre 1999, usually). Phase 1 motors had crank journal sizes of 48mm, or 1.8897".


Right.
Exactly why I think the 2002 WRX FSM dimension is a typo. The EJ257 and 205 journals are the same, I think.


Regardless, if they're both USDM motors (WRX/STI) then I would say they all should be 52mm crank journals, phase 2 cranks. IIRC, the crank we had pulled out of RiftsWRX's original motor (2002, EJ205) was a phase 2 crank, 52mm crank journals.

You should be able to measure the diameter of the bearings, approximately, by measuring from inside to inside of the tips on one half. What do those measure out to?

I'm not following you. My bearing thickness is correct. The big end dia of the Eagle rod shows 2.165....the stock EJ257 measured 2.166. I don't think the free diameter of any engine bearing will reflect the bearing dia under crush pressure....and besides, I don't have a ball mic handy. :) Keep thinking....I appreciate the help!

S.

Hmmm, how about putting the bearings together and putting a piece of string/wire around the outside and measuring the length (circumference). You can then divide it by pi and find the outer diameter. Subtract 2x bearing thicknesses from it, and you should have the inner diameter (at least a rough one).

I wasn't aware bearings weren't perfectly round when new, I've only taken them OUT of motors, not put them in. :)

Two things.

Axis had to order several sets of bearings to get ones that worked well with my crank. This was to resolve a clearance issue, the first set of bearing let the clearance fall out of range.

I did not know Eagle had rods that worked with the EJ257. They always list them as EJ18, 20, 22 only. I believe they will work. I called Eagle, but never got an answer about whether the rods work in the 257.

I'd choose "b" as the answer. I ordered some subaru main journal bearings, and when they showed up they were rod bearings. I can verify your stated bearing thickness range, but not the part number. Looks like maybe you have some "undersize" bearings.

I did not know Eagle had rods that worked with the EJ257.


They don't...so far. :lol: I'm working with Eagle to resolve this issue.
FWIW, I'm using the rods listed on the website.


I'd choose "b" as the answer. I ordered some subaru main journal bearings, and when they showed up they were rod bearings. I can verify your stated bearing thickness range, but not the part number. Looks like maybe you have some "undersize" bearings.

Not B...I used a ball mic, and the bearing thickness was correct, so it's got to be the differences in the rods. Stay tuned. ;)

S.

The potential problem I saw with the Eagle rods was not on the bearing face, but on the top of the "cap" between the bolts. Here you can have clearance issues with the crank or block in the STI.

I guess I'm not understanding. You have torqued down the rod bolts and measured inside (if their is a difference, you should be able to measure it). You know the diameter of the rod journal. You know the thickness of the bearing. All the measurements check out, yes?

The bearings are deforming because they are too "loose"? You rod journal is a little small.

The potential problem I saw with the Eagle rods was not on the bearing face, but on the top of the "cap" between the bolts. Here you can have clearance issues with the crank or block in the STI.


No clearance issues noted.


I guess I'm not understanding. You have torqued down the rod bolts and measured inside (if their is a difference, you should be able to measure it). You know the diameter of the rod journal. You know the thickness of the bearing. All the measurements check out, yes?


There IS a difference:

Journal (pin) dia 2.046"
Rod big end ID 2.165"
Bearing thickness .0589" (since posting, verified with a ball-end mic)

That leaves 2.0472", which should give me a oil clearance of .0012"...perfect in my application....it doesn't. Go figure. I've only done this 500 times in my life, so I trust my measuring equipment, but it doesn't make sense


The bearings are deforming because they are too "loose"? You rod journal is a little small.

No. The bearing crush and oil clearance isn't correct, according to A) Plastigauge and B) Bearing ID deformation. I tried the stock bearings, as well, so it must be the either the .001" difference in big end bore ID, or the .002" difference in beam width.

After speaking with Quirt, looks like I'm going to trust the stock rods and save the effort. End of story.

S.

There IS a difference:

Journal (pin) dia 2.046"
Rod big end ID 2.165"
Bearing thickness .0589" (since posting, verified with a ball-end mic)

That leaves 2.0472", which should give me a oil clearance of .0012"...perfect in my application....it doesn't. Go figure. I've only done this 500 times in my life, so I trust my measuring equipment, but it doesn't make sense
2.165-2.046=0.119
0.119/2=0.0595
0.0595-0.0589=0.0006" for oil clearance.

Is your math wrong, or am I misunderstanding what I'm calculating?

2.165-2.046=0.119
0.119/2=0.0595
0.0595-0.0589=0.0006" for oil clearance.

Is your math wrong, or am I misunderstanding what I'm calculating?

*2 = .0012" :D

Well, I wasn't sure if oil clearance was measured as a whole (diameter) or half (radius) dimesion. Heh, just made more sense to me as a half/radius dimension as that would be the clearance all the way around, instead of just on one side. :)

OK, now I see. You are measuring at 12 o' clock and it's ending up to tight, hence the idea on beam width being too narrow. I just hate stuff like this in the middle trying to build something--but it is the norm. Sorry we could not be of more help.

The stock rods are very nice and holding in cars with 550 whp at least for now. Since you are not pushing RPM, you should be good.

BTW....the Eagle rods fit.

It was a "feel" issue, in that I'm used to "feeling" anywhere from .002" to .003" on the rods (domestic), and my 257's .001" "felt" too tight. :D

Bump for move to "built engine forum" :)

S.