4ag Main Bearing stamp

[old_mr2]

Hi All

I am ready to order Main and Rod bearings for my 4Agze. When I checked the Mains for stamps I found that they differ (2, 3, 3, 3, 4)

Is this normal? On the sites I have looked at their seems to be no provision to choose Mark 1 2 3 4 5?

Please share your thoughts..

[Bazda]

Yes all the bearings will differ.

Toyota does I think 5 sizes for the mains. #1-5
3 sizes for the big ends. #1-3

If you buy from a Toyota parts dealer they will ask you what # bearings you need.
The difference from #1 to #5 bearing is 0.0006" (0.6 of a thou).
#5 bearing having the thickest wall center. #1 having the thinnest.
If you buy aftermarket bearings they are always made to the biggest clearance to be on the safe side therefore to #1 bearing of the Toyota specs.

[old_mr2]

Thanks Baz

Good info!

[trdee]

Yes all the bearings will differ.

Toyota does I think 5 sizes for the mains. #1-5
3 sizes for the big ends. #1-3

If you buy from a Toyota parts dealer they will ask you what # bearings you need.
The difference from #1 to #5 bearing is 0.0006" (0.6 of a thou).
#5 bearing having the thickest wall center. #1 having the thinnest.
If you buy aftermarket bearings they are always made to the biggest clearance to be on the safe side therefore to #1 bearing of the Toyota specs.

so if you want it to be "toyota tight" (as drifty says ) then your best bet is to get the bearings from toyota as they are the only ones who make bearings to all the right specs? no aftermarket people make them to all five sizes?

well i guess you could machine the crank to suit the aftermarket bearings, but yeh. sorry, thinking out loud lol

[Bazda]

so if you want it to be "toyota tight" (as drifty says ) then your best bet is to get the bearings from toyota as they are the only ones who make bearings to all the right specs? no aftermarket people make them to all five sizes?

well i guess you could machine the crank to suit the aftermarket bearings, but yeh. sorry, thinking out loud lol

Thats correct, if you want it to have perfect clearances you can only get Toyota ones.
Or you will have to get OS bearings and grind the crank.

No one makes them in all 5 sizes except Toyota.

[old_mr2]

Yep, I have some tgp bearings coming from Lithia Toyota Oregon. The only website I have seen so far that gives Mark 1, 2, 3, 4, 5 option. Mark 1, 2, 3 option for the rods.

[allencr]

Is this normal? Please share your thoughts..

Yes.
The factory grades are great, IF you've got a new/slightly used block & crank, otherwise with 15+ year old & worn parts, the grades are pretty much useless.
Also, it isn't just the grade of the block's mains but the cranks & when combined that gets the bearing number, right?

[oldeskewltoy]

[old_mr2]

Well I am worried about my Main Bearing Caps. I dont believe they are marked in order and I didnt mark them when I removed them! How can I know for sure which cap goes where?

[Bazda]

main bearing caps are always marked by toyota. 1-5 with arrows.

[troysota]

If my failing memory serves me correctly you can use the TRD bearings of the same spec with better oil grooves?

[Bazda]

The TRD ones will have chamfered oil grooves like the Toga bearings and ACL race bearings.

Toga


Toyota OEM

[troysota]

Am i also correct by saying that there is a colour code?

[Bazda]

On the Toyota OEM bearings there are no colour codes. just Numbers.

[old_mr2]

main bearing caps are always marked by toyota. 1-5 with arrows.

Checked this and you are correct. Phew!

I am just waiting on my crank balancing, then will be ordering.

Main 2, 3, 3, 3, 4
Rod 2, 2, 2, 2