rod bearing dilemma (major stuff up)

**urantia** · 08-03-2006, 07:56 PM

rebuilding a gen1 3sge, as part of the rebuilt new bearings were needed.

following local toyota's advice on how to get the correct bearings, (brearing numbers on the rod caps).which were 2 3 2 3 . Whent to toyota, said they will have a 3 week wait becuase they have to come from japan.

Well 3 weeks later they finally arrived, and all the bearings are marked 2! there are no 3's at all!!!! so i have size 2 bearings for all 4 conrods.

And i've just noticed some of the old bearings had a :"3" stamped on them, but the bearing cap had a "2" on it. In other words they don't match up, and as far as i know these are original from the factory as the bottom end hasn't been touched until now. So much for toyota's great wisdom on selecting correct size bearings, and also sending the correct ones. >

**oldcorollas** · 08-03-2006, 08:02 PM

grab some plastigage, get one of the bearings, and check them all out... i guess....
there may not be a huge difference between them in the end... or not big enough to worry? at least then you will know either way

**urantia** · 08-03-2006, 08:12 PM

i bought a micrometer/digital vernier calipers, are these accurate enough? or is plastiguage much better for measuring tolerances/clearances?

Got another 3sge to rebuild aswell, i should of whent with measuring up with plastiguage and going aftermarket bearings from the start.

**oldcorollas** · 08-03-2006, 08:15 PM

plastigage is better because of bearing crush etc.... and what you really want is the bearing clearence measurement anyway.

micrometer/vernier will tell you if the crank journals are still in spec, and will give you a hint of you need to undersize them...

i reckon if you assemble them with plastigage, they won't be too bad.... at least you know for sure if you need bigger/smaller bearings..... or you could get individual journals slightly decreased in size? that possible?

**urantia** · 08-03-2006, 08:24 PM

Was thinking of measuring the inside diameter of the rod with bearings and cap bolted up, setting the verniers to zero,.then measuring the journal which should give me the clearance. Ah feck plastiguage is the way to go for sure

Yeah could get the crank journals decreased and install oversize bearings, but have heard (dunno if it's true, and i'm sure you will know the correct answer) that it will take off the hardened metal surface on the crank journals, ah there is a better word for it i can't remember.

**RWDboy** · 08-03-2006, 11:01 PM

If the crank journals have been tempered/hardened in any way, then yeah you will need to get them re-hardened if you machine them (I'm fairly sure the 3S cranks are all cast).

In any case - the only way the manufacturer can get the crank journals to spec is to machine them *anyway* so usually re-machining isn't a huge deal. Plus, the bearing should be made of a softer material than the crank journal is as well, so wear should mostly occur on the bearing (rather than the crank).

I'm not sure where i heard this from, but I think the reason that Toyota specify certain bearing sizes is because they *don't* machine the journals to spec after casting - (not sure on that one though - sounds iffy). Instead they measure the journal and specify a bearing size.

Also - afaik - the difference between each bearing is 4/5ths of fuck all, somewhere in the realm of 0.0005 of an inch (that's 1/2 of 1 thousandth). So basically, i would suggest making sure that the clearances (check with plastigauge) are within normal spec, and then if okay - stick with the bearings you have got.

Killing a big end isn't that hard on a 3S-GE, so just be thorough and methodical and keep a list of all your clearances and don't get anything mixed up!

**urantia** · 09-03-2006, 10:43 AM

Thanx RWDboy, some good info there that i didn't know about!!

And your right the difference between a "2" bearing and a "3" bearing is 4/5ths of fuck all.
Will go with plastiguage just to make sure clearences arn't too out of wack.

+ rep added
Cheers Stu,RWDboy.

**rolleraction** · 09-03-2006, 11:23 AM

Yes RWD boy is correct. Personaly, I ditch the toyota gear and get the crank machined and use aftermarket (ie ACL etc) bearings. As much as I love my toyota's, the different bearing shells for respective journals in the 3SGE's is a crappy system.

I have some brand new toyota 3SGE (gen 1) bearings in the shed. You're welcome to have them if they suit. I don't have the part numbers on me at present, but can get them for you. Send me a stamped self addressed envelope and they're yours.

PM if you want

Cheers
Steve

**urantia** · 09-03-2006, 04:23 PM

Pm sent rolleraction.

**mullett** · 10-03-2006, 10:07 PM

hey man, or sure, get it machined. They'll get everything perfect, and you'll KNOW it's right. Plus at the same time you can get a nice dynamic balance and suchforth.

RM.

**urantia** · 11-03-2006, 02:31 AM

this motor if i can get away with it i'll use bearings i got from toyota/rolleraction, unless the clearances are too much still.

other 3sge i'll get machined, i just know the crank journals on this one are going to be scorched with deep grooves for sure, hopefully it's salvagable.

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