quick crank question

[bmoss85]

im about to start building the engine in the 90t that i just bought. i know that it uses the 7m crank that is better balanced but i already have a 6m crank that i have had turned and balanced for a another build i was going to do. will the 6m crank be fine or should i go with the 7m crank?

 

[Adjuster]

Honestly, both work fine.
But then again, it depends on who you talk to on here, and opinions on cranks being either slightly lighter, or slightly more in balance is the issue.

What do you want to do? LOL

It's your money. Have your 7M crank cleaned up if you think it will result in a smoother running engine, or use your 6M and possibly save some money.

The reality is however, if the block your using for the build is the same one the 7M crank is coming out of, and there is no damage to the journals, the BEST way to rebuild that engine is to use the crank that Toyota built it with, and the same size bearings they stamped into the engine.. (They will be sized the best if you go that route.)

If you have the crank polished, or machined, then it's all out the window however. It only counts if you use the undamaged setup from Toyota.

 

[bmoss85]

i tore down the engine last night with the 7m crank and it still had standard bearings in it and there was hardly any wear on those bearings and the crank journals looked great but i will have to have to mic the crank to know for sure how good of shape its in. thanks for the info

 

[Adjuster]

Excellent.

Now just decode the marks in the TSRM, and buy those exact same bearings for each main and rod journal.. They should fit perfect just like when it was put together. (There might be a different bearing for each one, and Toyota is the only source of bearings in those sizes that I know of, but the cost is not that much to get a motor put together to this level of precision.)

Good luck.

 

[IJ.]

Given the choice I'd take the 7M crank every time, I have run identically prepped early and late cranks in the same motor within weeks of each other and the 7M wins hands down for drivability.