How To Polish Your Crank Journals
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- čas přidán 23. 07. 2024
- #390fe #thunderbirds
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How to polish a crankshaft! In this video I will show you how to polish V8 crank journals to a mirror finish. I have done this on Honda cranks, Volkswagen cranks, Chevy cranks, and Ford cranks. This method of polishing crank journals has been done for many years. This method can be used to polish cam bearing surfaces, polish valve covers, polish wheels, and any other type of ferrous and non ferrous materials.
Yes machine shops will charge you $50-$100 for a polish which isn’t a lot for most but it is for some and any money saved is more money to put into the build.
This works on 4 cylinders, inline 6,V6, V8, V10, V12
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When people ask my why I do all the work myself and don't go to a profession I tell them "I know there are professionals that can do all of this better than me. I also know people that have paid professionals to get worse jobs done than what I can do... Looks amazing.
Couldn’t have said it better! Thanks brother! Plus every job is one climb higher!
The biggest problem with machine shops is they make the money machining parts. Why polish a crank when you can take .01 off and make more money. Why buy new rods when you can do all the machine work on your old ones and spend the same money on parts that can't handle the power. The guy doing my block started taking about blueprinting like he's gonna build a NASCAR engine. I'm like ya I don't think so it's the bare minimum buddy. I'll spend a little extra where it's needed to get it right I'm not going to space.
@@stoneyswolf i have always seen shops polish cranks and never saw one that didnt.
That looks really good . Im definetly going to redo mine with this method. I initially just used metal polish and microfiber, it was pretty good, but I definitely need to do what you did.
Thanks dude for taking the time to help folks!
My pleasure! This crank will be turning soon! Hopefully yours will be soon also.
Hat's off to you for taking the time and filming this process. Greatly appreciated as am rebuilding my 93 7.3 IDI and your video is informative and straight forward.
Awesome! Keep them 7.3’s tickin!
Dude awesome video thanks! Now I don’t need to pay a machine shop for the polishing service seeing it’s a simple task. Thank you for also being informative with technique and understanding how the oil can pick up grit if not careful. Cheers to you!
It should be cleaned when done.grit.dosent matter
Great Job! Very Informative!
Very helpful video, thank you!
Very well done
Great job!
Nice work.
Great job I love it
Nice work man.
Thanks for the video dude. I get what you mean about being a lot of work to make the video more so than the actual project... I do a lot of cool stuff at home too and think about recording it so others can learn, but it's pretty invasive to the process! And then you have to know what to say to the camera lol. Anyway I'm gonna be polishing up my newly purchased crankshaft for a 2.0L Honda engine. Thanks again, from Ventura CA
Well done sir! 👍 ✔
Great video! This will definitely help
Yes ! Super helpful ! !
very helpful and will do it
Great video man!
Thank you!
great video, it was very.... very helpful. thank you so much. BTW, this is the first time I watched your channel and I subscribed too.
Thanks brother! I have a baby girl coming in 2 months but I’m hoping after things get back to normal, I can make some more videos. Thanks for the sub!
Looks amazing
Thank you!
Great vid bro!
Thanks brother!
There u go, wallymart polishing job, great job. Should hit it with the 1500
😮 Nice job. I’m going to use your method on a old school bug crank.
Works great!
too bad youre not close to me ive got more bug parts than samba.
😂 where do you live?
Nice! Looks like it's Christmas
Haha thank!
im 79 and buy the emory cloths in a 1 inch wide roll. that is a neat idea though.
looks good..
good video. i feel the same way about making youtube videos. it could do my projects much faster without filming, editing, etc. and then just getting a bunch of complaints. but, i do think its worth doing to help people and educate.
That’s the only reason I do it! Thank you for the encouragement!
I like to grind off those casting ridges also
Good woork thank you good men 👍👏👏👏👏👏👏👏👏👏👏👍 mexico city DF
You got a like from me. That is awesome! Great job! I typically send my cranks out to the machine shop for polishing but they never come back looking as good as yours.. I will be doing this myself next time. My only question-about how long did you spend doing this? If you mentioned it in the video, I apologize but I missed it.
It could take you anywhere from 30minutes to an hour depending on how much polishing you need. Forged cranks are usually easier to polish and it’s easier to get a shine from a harder material.
The forged crank in my my turbo Honda prelude took a half hour. 9k rpm and going strong for 3 years making just shy of 600hp to the wheels.
how do you know that the necks need to be polished? if the finger and nail do not feel unevenness but a little dull, is there a risk of bearing damage? does it then wear out the bearings?
I'D LIKE TO SEE HOW YOU USE THE BLUE MAGIC
Use a clean shoe buffing rag cut into strips, a hockey skate lace, or a microfiber towel cut into strips.
Do you need to go to a 010 bearing when you do this?
You did fine work. Now, are all journals to spec? And, let's be speculative, if we may, and allow me to ask, if I were to keep my crank outside for a day or two due to conflict of working opportunities, can I add some type of heavy oil on the journals till next work opportunity? And, if that is not allowable. What can I cover the crank with until I work on it again; such as bolting it back on the block? What I fear is working on the journals, getting them just as you have, and then not being able to work on the engine for some days. What would you recommend I do? I will be working on my 4.6 in the near future but I want to fix the motor "old school". Have a great day.
Always store cast cranks vertically as they can sag over time horizontally (forged cranks don’t suffer from sag as much)
Honestly I use either white lithium grease or WD40 (water displacement 40th formula) because of their great covering abilities and easy wipe away. Use WD40 if storing in doors and you plan on getting back to it like a month later as it can dissipate over time. White lithium grease for months outside.
Cosmoline (rp-342) is harder to find these days but it’s great for years of storage. I have the stock cam sitting in cosmoline.
Some WD-40 is sufficient to prevent rust and is a little easier to clean off than oil.
Nice. I have a V-6 crankshaft in the bottom of a Nissan 3.3L VG33E long block, from my 1998 Pathfinder, 166,000 miles. Very clean and owned by an elderly couple since new. Oil pan is off. Block is sitting on its top in a tire giving me access to crank. It is a spare motor. It was having rod and/or main bearing knock. I found shavings in oil and filter. It had been oil starved from previous owner, due to a leak they didn't notice. First I had moonlighting mechanic try to refresh bearings. Nothing changed. I'm not sure he did it well. I had it pulled out and replaced with used motor. I want to restore the crank, flush motor with cheap vegetable oil and then diesel and put it back in. Any suggestions? My first time doing any motor block repair. Thanks!
Sorry to hear that! My suggestion is definitely locate where your metal shavings are coming from. Next: drop the block and crank off for a hot tank and tell the shop that there was metal shavings in the oil. This should also tell them to also clean the oil galleys in the block and crank if that’s not part of their procedure. Often when you have a bearing failure the moonlight mechanic doesn’t have the wherewithal to think to clean these oil passages and often this can contribute to oil starvation and more metal shaving build up. Some shops will do the block and not the crank also. Definitely ask what they plan on doing. If your crank journals are still in good condition (not scored) then a quick polish should do the trick.
Just saved me some money, we ballin on a budget baby!🤟🏼
Did you go to the next size bearing? Or will the oem one still fit and function
@@breezentheosescapades8769 the OEM size did just find, no binding or eating the bearings up
Ferrite burs. Sounds like the CGI scarabs from one of the Scorpion King movies, no? "And then, the guys was suddenly covered in ferrite burs and they ate him to the bone in like five seconds. It was AWESOME! Ya gotta see it, man!" :D
😂😂😂😂😂 you will be happy to know I am a fan of al the mummy movies! Love those scenes! Thanks for the support!
@@thestateofreal2533 Smart-assed comments aside, you do a good service to the motorheads about, and are faithful to be exacting about the terms. Kudos to you for that high standard.
Thanks brother I do try.
I'm interested to know the result of this work over a year ago now in the engine, Do you have a video of it running?. I come across alot of CZcams videos showing what people do with cranks but never showing the results of it put together turn key I'm not convinced to do it cos the clearances and ovality need to be miked if your putting new bearings
Watch my short with my turbo Honda prelude making 552 whp and 400ftlb of torque…rev limiter set at 8k rpm. I polished the crank on that engine like I have always done. When I made 450whp before the rev limiter was set at 9k rpm as I always race balanced my pistons and rods to go to that rpm.
I have a crank that is almost perfect but somehow and disassembly I have developed a burr, I can catch this bird with my fingernail is this something we can polish out at home in your opinion
My opinion is to use a file that’s not very aggressive and wider thank the but by 3x at least and without putting a lot of pressure…knock down the bur. All you want to do is make the plastic deformation (volcano) become flat and even with the rest of the journal. The spot will not disappear but making it flat and concentric is what maters
Could you use this method to restore a bad main journal on a crank to ten thou under? Asking for a really cheap friend...
The short answer is yes but it will be awhile. Cast steel is much easier to accomplish this then forged crank journals. Be sure to check concentricity as you go and diameter across the entire journal.
What most of the comment haters don’t know because they never ran a lathe…it takes forever to take .010 off unless you are using 60-80 grit and polishing down and even then it will take some time as you have to step down grit to get a polish and each time you do that material removal gets slower. This is why undercut journals are spun on a lathe while a mechanical belt grinder grinds it down.
Hmmm. There is an argument that supports the theory that drag (non polished surface) on the journals creates an oil wave that increases the oil film that reduces crank to bearing contact.
What are your thoughts on the topic?
Mine opinion lies with the Magnus effect as it is the main engineering around fluid bearing systems. Without the Magnus effect considered, even a polished surface under a microscope has grain structure enough to interact sufficiently with the fluid. You can see this in comparison visually with a freshly ground cast crank vs forged crank as the journals on the forged will look much much shiner.
How did you wash out the crankshaft vertically in a 5 gal bucket with gas or ??? don't want to leave the grit or stuff inside only to ruin your engine
Gasoline and an air compressor. I used little straw brushes as well to clean the oil channels.
Would have been nice if you would have measured it before and after. I know the loss is minimal but would have been nice to have concrete numbers
Yea I should have but didn’t have my micrometers in the basement at the time 😕
@@thestateofreal2533 How much material do you realistically use? Is it appropriate to use 0.010" undersize bearings if all you're doing is polishing in this manner?
@@jkpq8738 it all depends on how long you polish with more of the aggressive grits. All said and done I used .0008 of an inch polishing. Which is so minimal.
What about rust on the journal’s
I did this to my crank and there was still streaks (not deep, ran my fingernail through and felt no gouges) that were there before the sanding/polishing but they did clean up the line that forms from the old rod bearings, and there were much more "cleaner" i did it with wd40, 1000, 1500 grit sandpaper, and used metal polisher. Did i do this wrong? I didnt achieve the mirror finish like yours and if i were to run the crank like it is now with fresh bearings, would i run into problems ?
Nope not at all! Having streaks is okay as long as they don’t catch a nail and they are in the direction of rotation. Depending on if your crank is cast or forged you might have to use a lower grit number to get rid of streaks but keep in mind the more material you remove the larger your bearing to crank clearance gets.
@@thestateofreal2533 its just a cast 5.3 crank. Ill just install it like it is now, with fresh bearings, and hopefully not have any problems in the future. Thx man !!
@@carlosgutierrez2383 you will be good brother!
Would have liked to see how that one mared journal turned out
It came out good. The nick will always be there without being turned down but the biggest thing is knocking down the edges of the dent. I have a dented crank someone didn’t want in my turbo prelude and run it to 9000 rpm under 18psi. Makes 549hp on e85 before the nitrous 😈
Do you have any education in fluid dynamics? You started with an explanation of crankshaft polishing and oil film. What you missed was that the oil need something to cling to. In lamens terms, you can go too shiny and not leave the oil anything to cling to.
Tom how much metal did you take off when sanding for new bearings
My micrometers go out to tenths: .0007 was m the average deviation across all journals.
This can obviously change based on how much time you spend polishing and how long you stay at the lower grits. If the crank isn’t too marred up be in and out with the lower grits quickly. If the crank is really marred up then just expect the bearings tolerances to be a little wider when you plasti gauge. If they are wider than the prescribed assembly tolerance by .001 and you plan on smashing the pedal regularly, consider using an oil weight higher than the stock: 5w to 10w. I always use high zddp (900+ ppm) from a high mileage formulation.
You’ve taken time to prep your production except for the most important prep in a video production, your camera mount.
It’s funny you say that because in the production of this video I actually broke my original Tri-pod. I was trying to get a higher angle shot (POV shot) while I was polishing by setting it on a storage tub and my wife came down and swung the door open which hit the tub sending the Tri-pod tumbling over and cracked off the mount. I used cheapy old one I had for the rest of the video 🤦🏻♂️
Did you just rub the polish on there let it sit and then used the microfibers?
You can. No need to do that as we are just using it as an abrasive then cleaning it all off.
The only thing i have to say is did you do a measurement with a micrometer to see if the journals were even across their surface. they need to be in spec so your bearings don't wear out
You know I did! Concentricity and diameter were the same within .0008 (8 10th of an inch or .0203mm) from their original measurements. It’s important not to get crazy with this process as you can definitely take off more!
I went to college for machining at Thaddeus Steven College of Technology so I understand the importance of bearing tolerances. Thanks for asking!
@@thestateofreal2533 Good stuff its really enjoyable when you know you get it right.God bless
I like how you were careful with your rod bolts and I just hit them with a hammer until it moved...😂 (the last person to have it running locked it up.)
Haha hey you win some and you loose some!
@@thestateofreal2533 it moved....that's for sure...😂
🤣
If the crankshaft was polished to mirror...is it possible to use the standard bearing 0.0mm or need to use undersize one?
Depends on how much it takes to get it to a mirror finish. Use a micrometer to measure starting diameter and figure out the difference after you polish. Then determine if you need different bearings. Also consider using heavier oil for larger bearing clearances.
@@thestateofreal2533 can you give the tolerance for polish...let's say if the journal is 49.07mm....if we taken out 0.02m and final measurements is 49.05mm....is it still okay to use 0.0mm?
How much the measurements need to be taken out if we want to use undersize 0.25mm? Please advise
Yes 0.0mm STD is fine. .02mm (.00078) is so small it will not make much difference. I often polish to gain more clearance for high load engine builds to sustain better oil film and prevent spun bearings from thermal expansion.
@@thestateofreal2533 thanks....I just bought the std size bearings..and I would like to polish the crankshaft a bit..
I hope that I not overdo it...thanks .
After polish...what grade oil do you use? 10w-40 or 15w-40..... 5w-40 is consider too thin for larger clearances?
I use the OEM oil grade if I’m not planning putting the engine under significant load like running high rpm, using nitrous, or other forced induction systems.
Do you use the blue magic on the sand paper or did you do the blue magic on its own rag?
Also did you just use water on the paper if you didn't put any blue magic on them?
No blue magic is used with a piece of cloth. I used a strip of microfiber towel.
I used WD40 on the sand paper as it won’t cause corrosion but will still prevent the sand paper from loading up.
In the machining world we do this with debuting stones to remove swarf. They do the same in knife sharpening a well.
I've never been afraid to go low, ill start as low as 320 and work to as high as 3000
I an not being a smartbut in reply to your opening statement of,," IF YOU DON'T BELIEVE ME",,, I SAY IF I DIDN'T BELIEVE YOU I WOULDN'T BE WATCHING YOUR VIDEO. THANK YOU FOR THE CONFIDENCE TO MY CRANK.
Haha thanks!
does this have any effect on your bearing clearances at all or are you removing so little material that it isn't a concern?
Yes it does change your bearing clearance but if you are just polishing you might .0005 of an inch of clearance. Removing .001 takes a lot of effort on a lathe when you are polishing.
If your using the method shown in this video, you are not gonna be able to change the concentricity. I have done this three times on separate cranks forged and cast and they mic concentrical.
Aren't you removing material and increasing the tolerances. Not worried about spin-out?
Yes but not enough material to make a fatal issue for the oil film/pressure. What is spin out? Do you mean concentricity?
@@thestateofreal2533 ... 'spin out' ... is when the shell bearings break free and rotate on their own. For example, Mercedes Benz bearings have bearing tabs that align and are prone to it. I put a dab of red locker behind the shell. If the tolerance is too great, they break loose .
Never had that issue. Usually you mitigate that with a heavier oil weight. Iv built motors with .0025 bearing clearance. .0025 I ran 20w50 weight and had no spun bearings with the rev limiter at 8700rpm.
@@thestateofreal2533 .... I always plastigauge the clearances first. For example, if you have an older engine with slight oval stretch in the connecting rods, you will be on the upper limits of bearing fit. It's very easy to exceed that by removing crank material. If you plastigauge and specs are good, then a light polish is fine, but you know what DIYers are like with abrasives... lol
Yes I bore gauge and mic everything for that reason exactly. I have been spoiled though…I went to Thaddeus Steven’s college technology for machining. I would honestly never used stretch rods…your asking for trouble there.
Will it hold for 1000+?
I don’t see why not if your crank can handle that much. Oil film isn’t solely about journal polish though.
But when you polish doesnt you get diffrent tolerances?
@@kristoffermustonen5046 yes but if your trying to make 1000+ hp with a stock crank that can handle that hp, your gonna need more bearing clearance anyway.
I like your procedure. The only thing I disagree with is using a file for the burr in the crank.
I'd use a stone instead.
@@brettspaulding5855 I’m sure you have your reasons.
When I went to college to become a master machinist, one of the projects you have to do is square a bandsaw cut block of 1018 steel with a file. You have to come within .002 in perpendicularly, parallelism, and over all lengths. You do this with a machinists square and then it’s measured on an optical comparator. After we finished the project, our teacher said to everyone, “this exercise was not only to test your selection and use of files, but more to show you the accuracy and purity of the material you shaped.”
@@thestateofreal2533 At one time, not sure if they still do, the Canadian Military machinists on course were required to make a small machinist's vice with only a file and saws. The level of accuracy of our hands can be quite remarkable.
My uncle, a long time engine builder, taught me to polish my old Triumph motorcycle crank with a 1x4 board. You cut a hole close to the size of the journal with a hole saw (near the end of the board), then split the board in half lengthwise, splitting the hole down the center. On the end nearest the hole, use a piece of leather as a hinge tacked onto the end. Then you line the hole with emery paper, some WD 40 or other, and clamp the board around the journal (squeezing the board like pliers). Spin the crank with the board like a connecting rod. I just kept the crank in the crankcase half so we could spin it easily.
Leather belt strip works better .
I will have to try it on my next crank!
Dang, really should have jumped to a 3000 grit before the polish.
There would have been no point. They were mirrors.
@@thestateofreal2533 Definitely close enough bro 👍
I used vaseline when I was young and dumb
I’m assuming you mean on your crank 😉😂 haha hey whatever gets the job done. Money is no objected usually when you are young.
A machine shop left my crank kinda rough after a “polishing” and I not being a professional, figured they had some new technique. 200 miles later it started knocking.
How to crank polish your shangdangdangdang
So I turn cranks for a living I would never put that Crank in an engine the mains and rods are definitely out of spec out of round probably way to slick too I’m sorry but doing it the “CHEEP” way will cost you a fortune if you do this method that Crank needed to be ground to a lower spec then polished
My other crank has been turning 8800 rpm for 3 year under boost. 🤷🏻♂️
Looks nice but you ruin your tolerances. Moran.
😂 I can tell you haven’t ever done this. It’s a slow process and the amount you take off is so minimal…like a couple tenths of a thousandths. For my application, I plan on running a high zinc oil like a rotella 15w40…it’s not uncommon to run wider bearing tolerances when you do this or run higher rpm. Thanks though.
Dude did you really go thru the process of doing a vid and NOT set up some small dime store tripod ??? Wow OK Bro
Here at The State of Real, I am the director so I get to shoot video however I choose. Thank you for the encouragement.
For some it aint about the money ... in my country machine shops have no idea how to do this kind of shit 🤡
That gouge in crank is bad. Dont run it.
Watch me! Done it before! The 65 dodge coronet 500 has been running for 10 years. The current owner runs nitrous on it!
You are not supposed to polish a journal with both directions.
Wrong wrong wrong
Bloodviking
Here’s why that’s a wife’s tale…the Magnus Effect shows no difference in fluid film “capacity” whether the surface shows a high or low Spacial Frequency Roughness. Meaning the micro Burs that everyone was taught had to lay in the opposite direction to get the right fluid film and not degrade the bearings was simply untrue.