2JZ bearing sizes
- Thread starter 5uprahboy
- Start date
http://www.supracentral.com/foundation/mkiv-tsrm/engine-mechanical/
page eg104
Depends on the marks on the crank for what the original size was.
prolly best to measure them to find out first hand what they actually are.
page eg104
Depends on the marks on the crank for what the original size was.
prolly best to measure them to find out first hand what they actually are.
Indeed but the cranks have numbers indicating the size of the journal stamped into it. So even when ground down an even number across all 6 when you fit bearings one might fit tight and another loose. Best to machine all to the same size for the right bearing and clearance for the application.
I've measured the crank and the big end size is 51.75-51.8mm and the mains are 61.9mm. I measured these with digital callipers. So they might be slightly out. I will try and get crank around to my mates who has a micrometer to get an accurate reading.
But I'm just wondering, when you buy 10thou (0.254mm) oversized bearings, what is the base crank journal bearing size that this oversize measurement is in reference too? Is that Mark 0 on the TSRM, which is 61.998-62.000mm for the crankshaft main journal, and 51.994-52.000mm for the crankshaft crank pin?
But I'm just wondering, when you buy 10thou (0.254mm) oversized bearings, what is the base crank journal bearing size that this oversize measurement is in reference too? Is that Mark 0 on the TSRM, which is 61.998-62.000mm for the crankshaft main journal, and 51.994-52.000mm for the crankshaft crank pin?
They give the clearance specs for 25 over but not the journal specs.
because most machine shop when you tell them take 25 off there just going to take 25 of each one. but since toyota uses there select fit bearing system not all the journals are the same size so you end up with different sizes and different clearnances. what needs to be done is have the crank machined so the bearings have the proper oil clearnance.
because most machine shop when you tell them take 25 off there just going to take 25 of each one. but since toyota uses there select fit bearing system not all the journals are the same size so you end up with different sizes and different clearnances. what needs to be done is have the crank machined so the bearings have the proper oil clearnance.
The crank has been machined. I was told it was machined to 10thou over. I guess that's why all the measurements (as accurate as I can with callipers at least) are the same.
I just want to confirm the bearings I need are in fact 10 thou over, and out of curiosity, what does the 10thou oversize reference?
I just want to confirm the bearings I need are in fact 10 thou over, and out of curiosity, what does the 10thou oversize reference?
.010in is the next size in bearings. in the manual it is mm. which would be the .25mm refference.
hvyman;2017743 said:
Yeah but next size compared to what? I mean, from Toyota or any other bearing supplier you can buy standard bearing size, or 10thou (0.25mm) oversized, or 20thou (0.5mm) oversized.
Is the oversize of the bearings in reference to a base size of the crank +/- a certain amount. Or is it a comparative measurement between the crank journals and the block/cap sizes?
No. It's just the next size in bearings. It's like that for every motor. Std 10 20.
Can't make the next size too small as your already talking about a small amount.
Your over thinking it a bit it seems like.
Can't make the next size too small as your already talking about a small amount.
Your over thinking it a bit it seems like.
hvyman;2017765 said:
Appreciate you help, but I'm still not clear on one thing.
If my crank has been ground to accept 0.01" (0.25mm) larger than stock bearings, what diameter should my crank journals be?
The bearings that came out of the crank do have 0.25 stamped on them - but I'm curious as to what diameter my crank should be?
I mean, it'll be 0.25mm thinner than the STD size, but what is the STD size?
If you can buy STD, 0.01 and 0.02 sized bearings, those sizes must reference a base measurement.
The stock size how your crank came from the factory is marked on the crank.
If you read the manual that I posted you will see how the toyota select bearing system is.
The crank journals are NOT all machined to the same size from the factory.
If you read the manual that I posted you will see how the toyota select bearing system is.
The crank journals are NOT all machined to the same size from the factory.
I don't because if you look what your stock sizes are and subtract .25mm you should be close to the diameter of what yours are if they have been machined .25.
I don't have a magic book that tells what every engine should be at. Machine shops usually have a book but you shouldn't be machining to a spec in the book. You should be machining to get the proper oil clearance that your motor requires.
I don't have a magic book that tells what every engine should be at. Machine shops usually have a book but you shouldn't be machining to a spec in the book. You should be machining to get the proper oil clearance that your motor requires.
Yeah I get that. But my crank has apparently already been machined to take 0.01"/0.25mm oversized bearings.
On my crank are the markings 2222244
That would assume the last 2 journals were originally machined a little more from factory and from factory took slightly larger bearings to compensate.
Since the crank has been machined, and all the journals now appear to be exactly the same diameter (61.77mm), the original crank numbers are irrelevant for finding the correct sized bearings.
On my crank are the markings 2222244
That would assume the last 2 journals were originally machined a little more from factory and from factory took slightly larger bearings to compensate.
Since the crank has been machined, and all the journals now appear to be exactly the same diameter (61.77mm), the original crank numbers are irrelevant for finding the correct sized bearings.