Ordered my replacement Crankshaft please help.

[packinkimber45]

Hello everyone. I ordered my used crank today since my old crank had too deep of gouges on one of the journals. I got it from pinamotorsports, supposedly it only has 46k mi. I got it for $125 shipped with insurance, I think it was a steal. My question is, can I just take the crank to my local machine shop and have it inspected as far as being within specs? Or do they have to have the block and crank in order to see if it is within specs? Also what should I have done to the crank? As long as it is within specs... do I get it magnufluxed and micropolished? I have never done this before so all your input would be great. Thanks.

 

[VETTE_50_TH]

They shouldn't need the block. However. I would just call to make sure. I would get it dipped, mic'd, and polished.

James

 

[1992awdlaser]

You are going to have to measure for bearing clearances too.

 

[jlr2196]

They will not need the block, there are specs on the crank and the machine shop will have them in a book. The machine shop will clean your crank and if they are a good shop they will magnaflux it to check for cracks around the journal radius. Next they will check the journal sizes on the mains and the rods to be sure they are in spec. If they are worn too much the crank will need to be turned .010" undersize on either the mains or rods or even both. If the crank only has 46K and no deep scratches it will easily pass, mits cranks are hard and generally do not wear much. My crank has around 180,000 miles on it and I have had it out twice and it still is only .001" under new spec. I believe you can be under new spec around .0015-.0018". If you are building a serious motor (450 horse or more) you can take the block and bearings to the machine shop (assuming you know what size bearings you will be running) and have them install the bearings in the block, torque down the main caps and measure the bore size, then have them set an exact clearance by polishing the crank to the desired clearance you want to run. The same goes for the rods, you would take the rods and rod bearings in and do basically the same thing. This is actually blueprinting the motor to a certain degree but doubt you are going this hardcore with it.

 

[TOONAH]

I recommend that you use ACL Race Bearings and use ARP Mains Studs. I would also definately use Plastigauge on the Main and Rod bearings as part of your pre-assembly
routine. Plastiguage gives you some peace of mind that the bearings are a good fit.
You should also check your crankshaft endplay. Use a dial gauge if you can, feelers are not that easy to use in there especially if it a 7 bolt. If it is a 7 bolt crank you should torque the nuts down to 40 ft lbs if you are using the goop ARP sends you. The torque pattern should be like a cylinder head with a one piece girdle type main caps.

 

[jlr2196]

I would not recommend race bearings of any brand in a daily driver, I see this alot on forums. The reason they are race bearings is because they are made of a harder material or plating to resist the constant beating of a RACE motor, therefore they lack the embedability or softness of a standard bearing. The reason stock type bearings are softer is because in a daily driver that accumulates thousands of miles and over time gets small particles of debris in the motor, those small particles will embed into the softer bearing and not damage your crank or continue to circulate through the motor. A race bearing does not do this as well, but if you change your oil very often, and I mean every 2K-3K then you can do it. But think to the future or if you sell the car, as the years go by it seems people become relaxed on their maintenance schedule. I will also tell you that I have not seen to many motors that I have torn down that do not exhibit some particles of debris being stuck in the bearings, no matter how well they were taken care of and changed oil every 3,000 miles. It's just the way it is and the bearing manufactures and OEM know this and that's why there are standard bearings and race bearings. But do invest in quality bearings!! OEM, ACL or King bearings all seem to work well in 4g63's.