Probably the most valuable thing you've ever posted ;)

Just because it "works" doesn't mean it will make good power, or be reliable. The idea of dropping parts in an engine without machining seriously worries me.

Sorry, but I find it very unlikely that the Babbitt or shells on all 10x main bearing halves as well as all 8x con rod bearing halves were out of spec straight from Mazda.

Did you take the cylinder bore measurements yourself? Did you check main and rod bearing clearances with plastigauge yourself?

If I took my block to a machine shop and they told me that what you just posted was wrong with my block, first thing I would do is take it back home and measure myself. Don't take this the wrong way, but it would not be the first time a machine shop tells a customer that something needs this and that even if it does not so they can get the work. They make money by machining shit. Not telling customers they're shit is OK.

Fuck I mean, really? every single bearing half shell out of 18 pcs was out of OEM spec? Are we in the 60s were the Babbitt is cast on the shells with a pillow block? lol.
If all those bearings were bad straight from Mazda, they would be the world wide leader in COPQ (cost of poor quality).

I didnt take any measurements myself, but the 3 MZR engines he has done have all had the same issues with the OEM bearings straight from mazda... not sure about the "Ovaled" cylinders though.

Same shit happened to dustin with his bearings, they were all on the loose side straight from mazda.

@djuosnteisn

hmmmmm.
If the con rod bearings were off, I would suspect aftermarket rod bores could be out of tolerance.
On the mains is a different story.

The OEM rod bearings are out of spec in just about every build I've seen and read. It's fucking ridiculous!

That being said I believe DJ told me not too long ago they now offer both oversize and undersize bearings, which *should* fix the problem.

It just makes it so you dont have to get your bearings coated... the machine shop i went to just grinded down the crank to get the bearings in spec.

That's a pain in the dick for the whole "drop in" idea lol. Machine work to the crank isn't drop in by any means.

We need help from ACL Bearings :(

If the cranks have hardened bearing surfaces, that will ruin it. Once upon a time, I had to shell out ~$1k for a new crank in a V8 because of this....not fun.

well hasent ruined mine or dustins... dustin had the same shit done and he hasent had any issues with his engine...

Cant really say anything about my shit though, ran for 30 miles, now the fucker wont even start lol.

It won't ruin the crank, it just ruins the hardening. Thinking about it, I doubt any OE cranks go though a hardening process, so it's probably moot.

If someone coats the bearings it's because they are undersize, the coating compensates for that.
If you had your crank machined so the bearings would fit then the bearings would be oversize.

Seems like 2 different issues. The coating for undersize and machining the crank for oversize.

Am I missing something?

Yippie!

http://img266.imageshack.us/img266/8...6072315001.jpg

yes the fact that I am retarded. I did the same shit dustin did but at the time the undersize bearings from mazda where not available so dustin had his coated...

undersize/oversize... shit gets confusing lol

IIRC dustins rod bearings were .0022 UNDERSIZED so he coated them but he did not turn the crank. dont' know whats wrong with papa

@djuosnteisn
@djuosnteisn


wtf hapened with your shit? Im horrible at explaining shit.. All I know is I had my crank machined... and Im pretty sure dustin told me he also had his machined.

hahah

it doesn't really matter

Lot to take in in this thread

I was gonna ask for a short version, but, having kept up with it, I'm not sure that a short version would, could, really do it justice

Ya'll keep going.....

Do you remember if he measured the bore on his (I assume) after market big end rods?

Not too sure. I believe he was measuring bearing clearance and ended up .0022 under and the coating got him within spec

So IDK if the issue was due to conrods being too big or bearings being too small

I think that was the point of your question. :).


Tappin

Has anyone that had rod bearing clearance issues actually measured the bore of the rods instead of just bearing to crank journal clearance with plastigauge?

Sorry, but it's just hard to believe the con rod bearings from Mazda are out of tolerance. It is much more likely the bore of the big ends on some aftermarket rods are too big.

When these engines are built in the assembly line they are not checked for bearing clearance. They are put together and that's it. Miscellaneous parts are always measured at random but it is not part of the standard assembly process. If the fail rate on the bearings was as high as some have stated before you would see bearing failures left and right on these engines. That' s just not the case. Rods are weak but bearing issues are almost non existent. I could be mistaken but I haven't seen a single main or rod bearing issue on a stock motor yet.

That almost gives credence to the whole mantra of not having to bore out for new pistons. Maybe some inherent 'imperfection' allows the character of the motor to 'mesh' and run smoothly. How many times have you seen a motor done at a machine shop, to 'spec', fail for some stupid reason or another?

Get ready for a long arse post.
If you no want no read go to summary at the end.

Took some measurements of the bore on the big end of a stock rod and bearings. The manual does not actually have a tolerance for the big end bores. Just oil clearance and bearing thickness. It's going to take about 2 more weeks till I get the K1 rods since apparently they are on backorder. Once I have them I'll take the same measurements as below under the same conditions to compare.

This isn't some "engine rebuild shop" equipment. These Mitutoyo bore gauges are laboratory grade. Calibrated yearly. The granite plate where the measurements were taken is in an environment controlled room and is about 8" thick.
If you want more precise measurements than this you' re going to have to use a molecular nuerbuerg ring super fantastico neutron microscope.

Temperature. NIST standard is 20 degrees C which is 68 degrees F but I didn't feel like waiting till this shit cooled down to temp. For this purpose that's overkill anyway.

http://i1211.photobucket.com/albums/.../photo-7-1.jpg

Zeroing the gauge.

http://i1211.photobucket.com/albums/.../photo-3-1.jpg

http://i1211.photobucket.com/albums/.../photo-1-1.jpg

http://i1211.photobucket.com/albums/...t/photo-12.jpg

Measurements of the big end. 3x taken at 50*-60* rotations. Missing one pic. Don't know where the fuck it went. No bearings. Just bore.

-0.33275
-0.33275
-0.33285


http://i1211.photobucket.com/albums/...photo-10-1.jpg

http://i1211.photobucket.com/albums/.../photo-9-1.jpg

Now the bearings.

Zeroing the dial indicator.

http://i1211.photobucket.com/albums/...photo-11-1.jpg

The manual states bearing shell thickness of 1.495 to 1.519. All shells were 1.50 to 1.51. These 8x shells are new. Never used before.

http://i1211.photobucket.com/albums/...t/photo-13.jpg

http://i1211.photobucket.com/albums/...photo-12-1.jpg


Bid end with bearings. 3x measurements here as well.

-0.44865
-0.44875
-0.44870

http://i1211.photobucket.com/albums/.../photo-6-1.jpg

http://i1211.photobucket.com/albums/.../photo-5-1.jpg

http://i1211.photobucket.com/albums/.../photo-4-1.jpg

So.

The bore of the big end is 2.1671 +/- 0.00010 (2.49985--0.33275) That's 55.044mm (forget the last 2 digits converting to mm)

MEASURED: big end with bearings is about 2.05115 +/- 0.00020 (2.49985-0.44870)
That's 52.099mm

CALCULATED: big end with bearings is ID of the bore + bearing thickness = 52.044 (55.044 - (1.50 x 2)) That's about 0.05mm off from the measured ID of the rod with the bearings.

The crank pin OD as per the manual should be 51.980 to 52.000. If you go by the calculated ID of the big end with bearings in it you'd be out of tolerance ON THE LOW SIDE by 0.044mm. If you go by the measured ID of the big end with bearings you'd be out of tolerance ON THE HIGH SIDE by 0.099mm.

What does that mean?

Well, it could mean that the outer contour of the shells doesn't completely match the ID of the big end. OR, it could just be that the measurements are wrong. Assuming the measurements are correct, which I am going to do, you can think of the discrepancy between the measured ID and the calculated ID as the shells having a little bit of "spring" in them so that once tied down on the rod to the crank pin they'll sit just a little tight.

So is that the case?

Well let me whip out a crank and see.

Crank OD check. Looks to be within spec

http://i1211.photobucket.com/albums/...t/photo-14.jpg

Tie down the rod see if it turns.

http://i1211.photobucket.com/albums/...t/photo-15.jpg


Rod turned with no effort whatsoever. If you wiggle it (oscillation torque check) the rod turns freely. No slack can be felt. You could use plastigauge to measure clearance. I won't. To me it's good enough and that's how I intend to put the K1 rods on once I get them IF THE BORE IS WITHIN 0.02mm OF THE STOCK BORE.



Summary:

1. If you think the OEM bearings are out of spec IMO it's very likely the bore on the rods you bought is wrong and not the bearings.

2. If the bore on the aftermarket rods you bought is too big return them and get other ones. Grinding down the crank pins and using oversize bearings is the worst solution to this IMO. If the bore is too small What I WOULD DO, if it's less than about 0.1mm. is hone them a few passes at a time till they open up to spec. I know all the engine rebuilding fans will say that's wrong but that's my opinion.

Tomas, I'll pay your gas if you come over and help me do my motor build, LOL

@Tomas

are there any specs for the stock journals on the crank?

I need to get my hands on the FSM portion for rebuilding the bottom end.

Engine rebuild manual is in VIP :)

not just the FSM?

checking....

This.

2012-06-25_2338 - CrownImperial's library

Look at the stickies

I got it, I got it.

Still concerned about the rod bearing thing...but my thoughts are, big end too big, oversize bearings...........humm. Only gonna have a week of downtime for the motor to be dicked with....

Speaking of rod bearings... when I did my first teardown a year ago I popped the head, removed and put in new piston rings. Honed the cylinders and used the cometic (standard size) head gasket and some good head bolts (can't remember name). Unfortunately I didn't label my conrod bearings so I just had to through them in to each piston. As far as I can hear and feel everything is smooth and no rod knock.

Then again my engine has been low on power and have no idea what is causing it but engine seems to run fine :P

@Tomas any updates?

Haven't started the tear down. Waiting on web cams.
But I've taken additional bore measurements of both Eagle and K1 rods. Also performed plasti gauge check just in case although as mentioned earlier, I much prefer big end bore measurements than plastigauge. The instructions that come with the K1 rods also say to measure bore instead of using plastigauge by the way. Just in case people think plastigauge is the only way to do it because the Mazda manual says so.
The bores were all within spec. Not more than 0.01MM from OEM.

Only conclusion so far is that the Mazda OEM rod bearings being out of spec is very unlikely.

http://i1211.photobucket.com/albums/...photo-12-3.jpg

http://i1211.photobucket.com/albums/.../photo-108.jpg

http://i1211.photobucket.com/albums/.../photo-109.jpg

I assume you are measuring the actual crank rod and main journals with a good outside micrometer of some sort. How are they? Appearances can be deceptive. All I saw in the earlier pix was a digital dial indicator for the rod journals which, of course, would not suffice for rebuilding purposes.

The precision instrument used on the rod big end I.D. was amazing. You don't need that degree of accuracy, but I suggest that you do need at least a good outside micrometer calibrated with accurate standards to see whether the crank does need to be machined for oversize bearings.

So you are saying a micrometer is generally better than a caliper for measuring a 55mm OD pin? I would have to disagree with that.

Also, the measurements above are just to get an idea of the OEM and rod suppliers tolerances. That crank is a used spare. Not for the build. When the time comes for the "drop in internals" I won't measure the crank pins nor do plastigauge. It's going to be shit out and shit in over a week end.

Tomas,

pull the trigger on this already...i wanna do a drop in swap this fall and I need your input :)

but seriously....I am following you....do you have your own thread somewhere?

In two words: Emphatically yes. C-shaped real outside micrometer in 2 to 3 inch range with a calibration standard. You can get a Starrett for about $50 bucks or borrow one from someone. Accurate to .0001 inch.

Not questioning your plan or your capabilities and wishing you great success with the build. But suggesting that a digital caliper is more accurate and better for measuring and accessing wear on crankshaft rod and main journals would be unheard of in any reputable automotive machine shop.

Maybe not necessary for what you are doing, but it would be for me. Just one opinion.

Well Tomas, when I get my eagles I'll shoot you a PM, maybe send mine over to you for measurement as well.

Dano, no thread yet. But I'll start one at some point.

That would be awesome!

you are very thorough in your process and a writeup would be a tremendous asset for the forum. Since most guys build after ventilating the block there is little information on this route.

Even some of the guys that fully built had bearing size issues so this is especially of great interest to me.

I know a full writeup is a PITA but any information you can record and publish here would be extremely appreciated by the community I am certain!

Send'em

And that's one of the reason why I disagree. But opinion noted.

And Dano, this is all I have to say to you.