Rod bearing clearances...

[2ndGenGuy]

Okay so according to the Factory service manual, the rod bearing clearances for new bearings in my EK1 are:

0.020-0.038mm or
0.0008-0.0015in

With a service limit of 0.07mm or 0.0028in.

So I checked with plastigague and I got somewhere between 0.002 and 0.003.



The wierd thing is that this is the LAST bearing in the whole engine to be torqued down. All the other bearings were well within spec. The crank and rod bearings. I'm just wondering if this is normal to happen just because all the other bearings are tightened down, or if I actually happened to get one screwed up crankshaft rod journal, and it happened to be my last one.

If it's actually screwed up, should I just go buy a new bearing that is for the slightly smaller crank, and plastigauge it to make sure the clearance is tighter? Or am I okay?

Here is the page in the FSM so you can see what I'm referring to.

[88Accord-DX]

Your still within your service limit. The maximum service limit is .0028 in.

Thing thing about that is, once you get some milage on it down the road, you'll be loosing some valuable clearance you need. If you can get another bearing with 1 thousandths of an inch thicker & re-check your tolerance.

Edit- .003 in. is the one I'm talking about.

[2ndGenGuy]

Hmm, yeah that's what I was probably going to do. It's within service limits, but BARELY. It's less than 0.0005 inches from being out of service. It's somewhere between 0.002in and 0.003in. 0.0025 is way to close to 0.0028 for me to be happy considering all the work this is.

I think I'll pick up a new bearing tomorrow.

[offthahook]

Better safe than sorry. It's not like it's a stereo and you can just pull it out if something isn't quite right. These things are finicky. You don't want just serviceable, you want a good tight fit that will last and work right.

"0.0025 is way to close to 0.0028 for me to be happy considering all the work this is." Exactly!!

[2ndGenGuy]

Yeah so I ordered the new bearing. The original bearings were all 0.25mm undersized. I just went to the next size, 0.50mm undersize. It cost me more to ship the bearing than it did for the bearing itself. It's kind of a bummer because all the bearings are ACL bearings, and now I'm going to have one rod with an off-brand bearing... Oh well.

[Ichiban]

I would have first tried another like sized bearing first. Sometimes the tolerances just stack up the wrong way and that happens. You are gonna have to get the journal ground for the .50 under bearing?

Edit: Did you check the rods for round? If a rod end is egg-shaped it might cause this.

[2ndGenGuy]

How can I check for round myself? The machine shop was supposed to do that for me, but sometimes I get the feeling he didn't like working on my stuff...

[Ichiban]

the machine shop has a special tool that does this in like 1 second, but you can use a telescoping bore gauge and an outside mircrometer, and compare it to spec

[88Accord-DX]

Good point guyhatesmycar. If he has a outside micrometer, he can measure all his crankshaft journals for out-of-roundness & taper. Here is how I done it.

1. Now this is where the 4 measuring points come into play.
2. Make four measuring points on connecting rod journals.
3. The first measurement (A-1) is made to the left side of the rod journal at top to bottom of the journal. Second measurement (A-2) is made on right side of the rod journal from top to bottom. This is horizontal taper.
4. We have now measured points "A-1" and points "A-2". With the crankshaft in the same position, rotate the micrometer 90 degrees on the same plane as points "A", this is the point for "B" (vertical taper). Repeat what you did for points "A-1" and "A-2" at ninety degrees and you will have points"B-1" and "B-2", write these measurements down.
5. Taking the difference between points 1 and 2 in either "A" or "B" will give you the amount of taper on the journal.
6. The difference between points "A-1" and point "B-1" will give you the amount of out of round of the journal.
7. Do this for each and every rod journal of the crankshaft.

[offthahook]

Damn. This is where you start to question the machinists who worked on your block and the people who rebuilt your crankshaft and the manufacturer of the bearings. It's not a game of inches anymore; it's a game of thousandths of inches. EVERY time I have had machine work done, I have made a point to mention that "this is an older HONDA block/head. You may not have seen too many and none recently. When Honda says '1/1000th, that's what they mean. No wiggle room, champ." I've always, of course, been reassured that the machinist knows what's up. I know 2ndgenguy knows the 411 about all that, too. It sucks to have to recheck someone else's work, esp. if they have specialized tools/skills that we don't. I wish I were more help, but it could be a manufacturing issue with the bearing itself or the machine shop might be a little off or a combination of both. Measure it out if you can, but the machine shop should have done that lickity split when they worked it over. Too bad they don't have DIY machine shops where us anal types could really get down on our own stuff. I guess it's like any other job-- they do a lot of stuff (dealer warranty work) and maybe don't pay attention like they should to our stuff!

[2ndGenGuy]

Maybe what I'll do is take that one rod down to another machine shop in town. If it only takes a second to check if it's out of round, it shoudln't cost me too much money. A few bucks for a little extra insurance is worth it to me. If that one is out of round, I'll take all my rods in and have them rechecked.

If the rod is okay, I'll take in the crank and have it's size checked.

The precision of these things truely does seem important. The book shows tolerances down to the ten-thousandths of an inch. This means there is really absolutely no room for error.

And um taper is a bad thing eh? I noticed when I was doing the plastigauge, there was a bit of taper in the journals. Since I was told in the manual to measure the Plastigauge at it's widest point, I assumed that this might just be what Plastigauge does sometimes. Can you tell from the Plastigauge if there is taper, or is that an inaccurate way to measure?

I'm beginning to think that this "remanufactured" crank I bought might be junk. I've got the original crank, and it might be worth it to have that all machined down to size...

The reason I didn't use the original, was the sealing surfaces were all scored on the ends. I didn't think that this could really be fixed any way, and seeing as how it might need to be sized anyways, a new crank would be the way to go...

[88Accord-DX]

Here is some facts on taper & a good read on bearings for you 2ndGenGuy.

To check the roundness of the crank journals, measure each journal’s diameter at either bottom or top dead center and again at 90 degrees either way. Rod journals typically experience the most wear at top dead center. Comparing diameters at the two different positions should reveal any out-of-roundness if it exists. Though the traditional rule of thumb says up to .001 in. of journal variation is acceptable, many of today’s engines can’t tolerate more than .0002 to .0005 in. of out-of-roundness.

To check for taper wear on the journals (one end worn more than the other), barrel wear (ends worn more than the center) or hourglass wear (center worn more than the middle), measure the journal diameter at the center and both ends. Again, the generally accepted limit for taper wear has usually been up to .001 in., but nowadays it ranges from .0003 to .0005 in. for journals two inches or larger in diameter.

Here is the link I got this from. http://www.aa1car.com/library/ar797.htm

[Ichiban]

ddude, I'm suggesting that the big ends of the rod's themselves need to be checked for round as well, and if out of round, the cap should be machined and the big end bore honed back to spec. There should be directions for measuring this in the book. John, the plastigauge should appear as pretty constant widthwise, and you're right. If it's not, that would suggest taper in the journal. With a micrometer, you can measure the way ddude explained. Oh, and for you all, ALWAYS double check the machine work, never assume it's right.

[2ndGenGuy]

Well, I haven't had a chance to screw with any of that yet. But I have a suspicious feeling that the problem is that Crankshaft from eBay. The jerk that shipped it didn't even pack it in anything. It came in an empty cardboard box. The bearings were in the same box, but they were nicely tucked away and packed so they wouldn't be damaged. But fuck that crank was just in the box flying all over the place. Dickhead who sold it didn't even have the decency to wrap some newspaper or junk mail around it...

I think I'm going to take the original crank down to the machine shop and just have it sized to -0.25. I totally don't trust the "new" crank that I got off eBay. If he machines it, and all my clearances come out good when I put it in, and the Plastigauge doesn't show any taper, then I'll be happy.

Again, I appreciate all the advice from all you guys. I've learned a lot from this build. I think that when I finally get it together I feel pretty confident that it won't fly apart on me!

I'll post my results in my EK1 build thread.