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Discussion Starter · #4 ·
Well the journals on a crank that have been resurfaced will be smaller, needing bearings with a smaller inside diameter, thus undersized. Correct? Sorry if I got my terms wrong, but I can do without any smartass comments, you know what I mean.

I'm looking for bearings that are 1 or 2 thous...
 

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No i don't think we know what you mean. If you cant handle a little playful banter, then you might need a few callouses on you feelings.
 

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boomerang opeler
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when you regrind a crank the journals are as you say under size but the bearings have to then be oversize to take up the diff
they are white metal bearings not needle unless you have some super exotic trick engine that no normal shop would know what to do with and a needle bearing comes with an inner and outer race that do not split so you would have a compound crank
and the least a regrind will take off is 10 thou so they were not smart ass coments just a straight question to get an answer to give you a good answer in return your machine shop will have given you a size that they reground to if you give us that we will be able to tell you the size you need but it will not be a
"I'm looking for bearings that are 1 or 2 thous..." it will be a fixed number

this comes to you without any smart ass comments just simple questions and concise answers so please respond with polite replys
 

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I meant no harm, I was just wondering if you had an oversize crank. if it were then where you got it was my next question.
 

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OGTS sells them on a regular basis. Keep in mind the crank needs to be groung to the new bearing size as the block your using seats them. It's a common missconception to think just grind it and go with it. Opel CIH motors are very critical of bearing clearance to maintain oil pressure. I'm only pointing out some facts from experience...some good and some bad. Trust me, it ain't a chevy and the rules are different.
 

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Perhaps what 73 has is a crank like mine that has standard size journals but came out a bit "small" after polishing. My bearing clearance came out just under three thousandths, yes a bit loose but that's okay for speedway use I think.
If this is the case, 73, and you need tighter bearings, I think you will have to grind the crank and use undersized bearings. Grab those -10s from T6, what a deal, then find a machine shop that won't ruin your crank. Make your machinist come here for expert help in grinding specs, there is something funny about them as I recall.
As for your question about different bearings, I think there was talk once here about using different rods, that could maybe change your rod journal dimensions but we're going into the topic of razoo exotic high tech engine building now...
I hope we don't get another lecture about tact and politeness, maybe we all need that group hug I mentioned in another thread today...
 

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Discussion Starter · #10 · (Edited)
I dunno, that #3 post just irritated me when I read it, sorry. Should just straight up ask what I meant if you don't under stand me. But anyways,

I have one crank rod journal that is a little small and is causing a rod knock under load. Has good oil pressure yet even with the knock.

All I want to know is if .001 and .002 bearings are availible and where to get them.

My Sealed Power catalog calls them undersized bearings.
 

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boomerang opeler
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cant see anyone making a bearing so small a diff from standard , if you read the catalog you will see numbers like .010 or .020 or .030 as these are the normal resize jumps
if you feel you must have some new ones then just go for a set of standards as the diff is probably just a little wear on the standard ones
but 1 thou is nothing
 

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I'm sorry, I didn't get it nomally a crank is stock or undesize requiring oversize bearings. that is why they call them like a plus .010. It makes it hard to answer a question if you state it backwards. All I did was go on what you said which meant you had an oversize crank and were looking for an undersize bearing. An oversize crank would be a nice find, Don't get excited at others if you stated the question backwards.
 

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Old Opeler
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"Knocking"

If that bearing is knocking you would soon know all about it. Usually there has to be considerable excess clearance for a rod journal to knock - at least 0.005" clearance OR a blocked oil way in the crank not letting oil through to that rod journal. It is more likely that any knocking with good oil pressure is in fact the pins in the pistons. This knock sounds a little higher up in the motor if you use a stethoscope to listen to it - or even the handle of a screwdriver against your ear with the blade on the engine block.
The determining factor for bearing replacement is the taper from end to end and the ovality of the journal itself. Carefully measure the journal to see what shape it is in. Standard rod journal diameter is held quite tightly by Opel at 2.0464" + 0.0003 minus nothing. Standard rod bearing clearance is 0.0006" to 0.0023" on a new journal; so up to 0.003" would be tolerable for worn bearings.
If you do have a bearing clearance problem that is only 0.001" to 0.002" then by selectively installing NEW replacement standard size shells in a rod that has been freshly resized to the minimum size you may find the the clearances are pushed back into tolerance.
The rule here is measure everything accurately and selectively assemble the shells with the tightest tolerance.
Opel only used standard and 0.010" (0.25mm actually!) undersize bearings in production and did not resort to the 0.001" and 0.002" undersize bearings that some of the "other" GM Divisions used in production.
The crank is ground "undersize" when reconditioning so, logically, the bearings that fit it are "undersize" - at least in the hole in the middle which is what matters! I guess the shells are actually thicker so that is where people get the idea that they are "oversize"! ;)
 

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I have some Repco 40 under bearings (meaning the crank is turned down 0.040)

p.n. 5m1342al-040 i think i got them from OGTS

Also clvite makes bearings but I cant find the p.n.

there was some talk about turning the crank down and running Honda bearings but you would have to talk to rally Bob about that

something about Honda using the same bearings in the F1 motors as they do in the production cars

But thinking about it if I had the money a F1 team has I would be using a roller crank.

HTH
Davegt27
 

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Ah, the excitement of the mundane. I don't mind a little friendly ribbing, when it is done with humour and decorum. But Dave, don't be pissing in the other members cornflakes, especially when you are wrong.

The correct term IS "under-size" for journals that are ground down to a smaller diameter, and "oversize" for cylinders that are bored to a larger diameter. And don't start arguing, because I'll just quote the Opel Factory Service Manual that lists the "Dimensions for grinding crankshafts for use with under-size bearings". That's the proper terminology, and used throughout the industry.

Crank main and rod bearings are only available in "standard" under-size dimensions, unlike factory pistons that come in various "ranges" of diameters, with up to 5 thou of difference between the ranges. Bearings can only be bought as either 0.010" or 0.020" under-size, OR 0.25 mm or 0.50 mm under-size. And while that is close to being the same, my very precise machinist tells me that there is a "slight" difference, so be sure you know what bearings you are getting BEFORE you get the crank ground.

JM2CW
 

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Keith I'm a machinist by trade if you have an undersized crank then you need oversized bearings. The original question was where to get undersize bearings, not where to get bearings for an undersize crank. If you read back I already appologized for any confusion. There are a boatload of odd parts out there for Opels so I went with the question posed. An oversize means by all terms a bearing that is over stock dimension. I asked apologized for any confusion and suggested a source.
 

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Discussion Starter · #18 ·
What is exactly measured on the bearings when you get under/over sized bearings? If its the inside diameter I'd say its undersized but if its the shell thickness it would be oversize.. I don't know. I've always heard them called undersized, sometimes oversized, but its pretty much understood what theyre talking about even if it aint the same terms I use. Never heard of an oversize crank journal.. I believe the correct term is undersize but whatever.
Here is a copy and paste from the Summit web site on rod bearings "These are available with various under-sizes including 0.001 in. of clearance for polished journals."
OK enough with the bickering already, It was just a simple misunderstanding. Whos right or wrong dosn't matter. Sorry if I offended anyone, din't mean to.
 

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SeventyThreeGT said:
OK enough with the bickering already, It was just a simple misunderstanding. Whos right or wrong doesn't matter. Sorry if I offended anyone, didn't mean to.
There is no reason for you to apologize. According to the Opel Factory Service Manual, and four sets of bearings that I just bought for my under-size ground cranks, you are correct. Dave is just being a pain. Simply put, this reminds me that I need to spend more time working on my cars, my house, and my life, and less time here. And with that, I bid you all adieu. See you at OMC, if you happen to get there this summer. TTFN...
 

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Bearings

Wow, sometimes reading these forums makes me glad I am a cardiac nurse by trade. How is the blood preasure? Some people go out of their way to keep me in business.

There are no bearings made to "just take up a little wear". You get them .010, .020, .... Then you cut the crank journals the minimum needed to take out any grooves or other damage to fit one of these "undersize" sizes. If you have damage to your bearing surfaces and you can hear tapping from the crank related to this then no matter what you oil pressure is you need it fixed. I have never seen a bandaid on a finger fix a heart condition. Though I have been give the "finger" at times. (humor)

Keep it coming, guys. If no one has told you they love ya, today. I do. But not in the biblical sense.

Mike
 
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