Crank polishing

Marvin Robinson · 05-27-2014, 11:20 AM

Got a crank that needs polishing to get another .001-.0015 on the rod throws. Anyone have a method for doing this in house, or is a machine shop the ONLY way to get this done... trying to meet a deadline.

carl hinkson · 05-27-2014, 11:30 AM

You should never try to polish crank to remove material for clearance as you will not have flat journal in the end.

Ed Wright · 05-27-2014, 12:40 PM

Can't find +.001" bearings?

john corcoran jr · 05-27-2014, 01:23 PM

Marvin,
You could just "polish" the bearings instead. After all, aren't they made of a softer metal than the crank? I'm JUST KIDDING. Just call the crazy Ukarainian and I'm sure he will get the right parts for you before you even get back out to the garage.

Marvin Robinson · 05-27-2014, 05:09 PM

Bearings are already .001 oversize and coated so I can't polish them, no .002 available. Looks like a trip to the machine shop, I don't have access to a lathe.

okieracer · 05-27-2014, 06:32 PM

You can't polish what you need in the crankshaft. Get the bearings you need undersize and have your crankshaft grinder set the clearance with the crank grind. If you try to polish the journal will be swaybacked.

Rick Leininger Jr. · 05-27-2014, 08:35 PM

Open up the rod bores to max spec, if that don't put clearance to where it needs to be, grind the crank -.010".

Marvin Robinson · 05-28-2014, 02:14 AM

Won't resizing the rod end change the crush on the bearing?

Rick Leininger Jr. · 05-28-2014, 06:34 AM

Quote:

Originally Posted by Marvin Robinson

Won't resizing the rod end change the crush on the bearing?

The range is usually only .0005", if your rod bores are slightly undersized, going to max bore spec may get your clearance closer to where you want it to be. Removing the flashing from the back of the bearing shell with Scotchbrite can help gain a tenth or two of clearance as well.

Mike Taylor 3601 · 05-28-2014, 09:08 AM

Quote:

Originally Posted by Marvin Robinson

Won't resizing the rod end change the crush on the bearing?

Rods could be @ low side (small side) of spec,if they are new rods maybe under spec,new rods need to checked also,most are left under specs about .0005. just don't go over high side spec of rod housing bore
Try to polish that off crank won't be good,can't remove that much evenly by polishing
BTW if make journal .001-.0015 smaller clearance will open up around .003 or more,I think you meant you want to increase your clearance .001-.0015,but thought I would mention that just in case
Mike Taylor 3601

05-27-2014, 11:20 AM	#1
Marvin Robinson Member Join Date: Jun 2005 Location: Gary, IN Posts: 139 Likes: 0 Liked 0 Times in 0 Posts	Crank polishing Got a crank that needs polishing to get another .001-.0015 on the rod throws. Anyone have a method for doing this in house, or is a machine shop the ONLY way to get this done... trying to meet a deadline. __________________ Marvin Robinson 3188 STK/SS

05-27-2014, 11:30 AM	#2
carl hinkson Member Join Date: Feb 2007 Location: NORTHEAST Posts: 287 Likes: 1 Liked 18 Times in 10 Posts	Re: Crank polishing You should never try to polish crank to remove material for clearance as you will not have flat journal in the end.

05-27-2014, 12:40 PM	#3
Ed Wright Veteran Member Join Date: Mar 2005 Location: Sand Springs, OK Posts: 8,132 Likes: 896 Liked 390 Times in 170 Posts	Re: Crank polishing Can't find +.001" bearings? __________________ Ed Wright 4156 SS/JA

05-27-2014, 01:23 PM	#4
john corcoran jr Junior Member Join Date: Oct 2003 Location: darien, il Posts: 53 Likes: 0 Liked 16 Times in 10 Posts	Re: Crank polishing Marvin, You could just "polish" the bearings instead. After all, aren't they made of a softer metal than the crank? I'm JUST KIDDING. Just call the crazy Ukarainian and I'm sure he will get the right parts for you before you even get back out to the garage.

05-27-2014, 05:09 PM	#5
Marvin Robinson Member Join Date: Jun 2005 Location: Gary, IN Posts: 139 Likes: 0 Liked 0 Times in 0 Posts	Re: Crank polishing Bearings are already .001 oversize and coated so I can't polish them, no .002 available. Looks like a trip to the machine shop, I don't have access to a lathe. __________________ Marvin Robinson 3188 STK/SS

05-27-2014, 06:32 PM	#6
okieracer Junior Member Join Date: Jul 2002 Location: Durant Posts: 8 Likes: 0 Liked 0 Times in 0 Posts	Re: Crank polishing You can't polish what you need in the crankshaft. Get the bearings you need undersize and have your crankshaft grinder set the clearance with the crank grind. If you try to polish the journal will be swaybacked.

05-27-2014, 08:35 PM	#7
Rick Leininger Jr. Member Join Date: Jun 2007 Posts: 162 Likes: 0 Liked 0 Times in 0 Posts	Re: Crank polishing Open up the rod bores to max spec, if that don't put clearance to where it needs to be, grind the crank -.010".

05-28-2014, 02:14 AM	#8
Marvin Robinson Member Join Date: Jun 2005 Location: Gary, IN Posts: 139 Likes: 0 Liked 0 Times in 0 Posts	Re: Crank polishing Won't resizing the rod end change the crush on the bearing? __________________ Marvin Robinson 3188 STK/SS