7MGTE rebuild question about crank specs

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89_turborunner

New Member
Oct 1, 2006
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Today I got the pistons in my 89 7MGTE, and a few of the rod bearing clearances were about .01mm over spec, came in at .070mm, spec is .060 (from plastigaging). Should This worry me or is it close enough? Also, there is a little bit of blue coloration on the crank (the rough cast part by the rod bearing surfaces). I know this is from heat, but is it normal?

My machinist checked all the crank journals for roundness and diameter and said they're all within OE spec, and he polished them for me.

Anyone with experiance please chip in
 
Nick M

Nick M

Black Rifles Matter
Sep 9, 2005
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Where did you come up with those numbers? Toyota lists the rod clearance standard at .021mm-.053mm.

Discard size is .070mm, meaning (from toyota anyway) that the crank needs to go in the garbage. But they don't have to pay for a new one. I would have it turned down by the slightest amount and install new bearings to the correct clearance. You do not want to take much off of a Toyota crankshaft though.
 
supra90turbo

supra90turbo

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Mar 30, 2005
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The hardening is very shallow on the crank journals. If you have to go undersize or especially 2nd undersize, you're better off buying a new crank from Toyota.
Basically they want you to buy a new crank if you need to machine it.
If you're going to have it turned down a size or two, at the least you're going to have to have the journals nitrided and heat-treated.
 
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89_turborunner

New Member
Oct 1, 2006
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Oregon
Nick M said:
Where did you come up with those numbers? Toyota lists the rod clearance standard at .021mm-.053mm.

Discard size is .070mm, meaning (from toyota anyway) that the crank needs to go in the garbage. But they don't have to pay for a new one. I would have it turned down by the slightest amount and install new bearings to the correct clearance. You do not want to take much off of a Toyota crankshaft though.
Click to expand...

My TSRM is a 1995 publish date for the 1989 supra engine only. It states standard clearance of .030mm-.048mm, with the maximum clearance being .07mm.

I did re-plastigage the two bearings that were on the loose side, and they came in at .038mm. I made sure to clean every singe surface and the hardware this time. I guess there was some debris in there or something.

So now there are 5 bearings that are .038, and one between .038 and .053. I think it is good.

Thanks for the info about the heat hardering of the crankshaft journals. I was concerned.
 
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