How to polish a crank ( crankshaft )
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- Опубликовано: 6 янв 2011
- Engine-Guru.com Presents a video on how to polish your crank shaft. Any questions call 616-430-3114 ask for KYLE.
We are located out of Grand Rapids, Michigan. 
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I had a crank where the rear main seal wore a groove, so I took some JB weld and put it in the groove and spun polished it on a rig I made, it made the groove perfectly smooth and never leaked.
GREAT video! I feel informed enough to call a shop for service now.
Great video , i like how you did the QnA at the end
Appreciated the video. Good Job of demonstrating.
GREAT VIDEO!
Nice video & well done.
Very good answer.
great work
Good informative video.
Gr8 trick, thanks for sharing this trick
Good video!
good video amigo
@enginesRmyLife that's right buddy,been building engines for 30yrs.All journals have a blueprint tolerance on main,bigend,cam,aux,balance shafts sizes usually 0.001 maximum(top) to minimum(bottom),even when a shaft is reground its always linished not for sizing,polishing the grain from grind,golden rule,if you can feel or even see a scratch it needs regrinding.More clearance = less oil pressure = failure and 400-500 grit paper can be used,but deglaze paper,no sparks at all,sparks is metal
That groove on the seal surface that remains can take out a seal real fast.
silicon212 Never did for me. I took a groove twice as bad as that, smeared JB weld in it smooth with a razor blade then polished it on my lathe. Still doesnt leak.
That's what Speedi Sleeves are for.
Cleaning up the mains with that hand held belt sander would be OK I would say but if the big end journal's had worn oval due to compression pressure the belt would follow the same form and would surely wear out the shell's in no time at all, before I retired I worked on a cam and crank cylindrical grinder in an engine refurbishing company and we never used this method.
actually that's polishing as far as I can tell. Every time I've seen it done was either this way or with a "polisher" for cranks that've been chamfered for increase flow.
Its to ensure bearing life. As long as everything is to spec, the motor lives it takes out any impurities off the finish to make sure it doesn't eat your bearings. A small pit of rust can destroy a bearing fast and cause catastrophic failure ie blown motor.
My Chilton manual said pullout your she laces get 600grit wet paper wrap it and pull it back and forth till it erupes.
about how much is the cost to refurbish a crankshaft and do you do heads and Blocks also. I have a 216 motor in my 49 chevy fleet line and looking at rebuilding it
Sir can you do a tutorial on how to setup amd grind the cranshaft.Thankyou
SUPER
Great now I can go to my local parts store where they loan tools & borrow a crank polisher .
Guess I'll borrow a head machine boring bar crank grinder & jet wash while I'm at it .
Ha ha you funny smart ass fkr!! What parts store do you use? :o
+B Ann
If your( re-)building engines you should really have a knee mill and lathe .
+Mark Rich Rather have a cylinder "head machine" with an air float table designed specifically for replacing guides and seats.
B Ann
If thats all you do is head work. Its good for nothing else . A nice 3 axis cnc knee mill and cnc lathe will be much more versatile. I make beautiful cnc parts , do head work , deck block . All in my home shop but the down fall is I can only fit so much in my garage. So I have to pick and choose what will be best for all my projects , hobbys.
Mark Rich
Seems you never have everything you need or the room for it.
Then if by chance you do get it it's near impossible to find competent people willing to work.
If I had my life to do over I'd find a good job somewhere and just tinker in my spare time.
Naw, probably not.
@woodwardcars
he is not using "sanding belts" they are buffing belts. they use same grit labeling system as sandpaper, but feels more like 3m scotchbrite pad. if the crankshaft journal is measured to be within specification in size and out of round, then it can be polished with paste. even extensive polishing will not remove more than 0.0005" inch.
because there are 2 connecting rods per rod journal and 1 main cap per main journal on (most) V8's.. i.e. the rod journals are 2x as wide as the main journals.
The crankshaft is being polished and will be checked with a mic to check proper clearances .
All of my best efforts building winning 305 Cu" stock car engines stock had honed cylinders course stones , chrome rings, swirl polish OEM valves, lapped & 30 degree back back cut to narrow the seat on the valve, with STD/STD by hand in a lathe 2000 grit polished side to side /journal/ around each ,bent chunk of steel with parallel lines , weighed all the valves equal weight 8 in/8ex. However I did use an old set off 16 followers and ground a bunch of the bottom of each in an old valve grinder & equal weight STOCK PARTS o, yeah 283 cam bearings ./ It kept winning until it was run low on life blood by a troublemaker . I would not build an engine for that dipstick , that just a couple of my favourite things . Grumpy's book really helps cooling/more advance timing. I love SBC James T.Burke Motor Mouse
15 years ago they did,nt have the [INTERNET today is like having a teacher 24 hours awesome!!!
What instruments use polish the crankshaft?
I have done it at home with emery cloth. but I wont ever say do it. like he said take it to a shop. but it was one of them times I had no choice. plus it was a old dirt track motor. and was meant to get me threw the weekend. I got lucky and it lasted half the season.
Use crocus cloth last.
Unless your a machinist, you shouldnt "rebuild" cranks.
I have a huge question...whats the need for this step...If you dont do it will the bearing start knocking???on a rebuild engine...im curios...Send me a message plz
Really, that's all there is to it? I realize you have $thousnads in tools. What grit are the sanding belts?
Nice vid.
What about the roundness of the journals , scratches only hold oil!
Well if its in serviceable conditions you can have larger size bearings...
Why does he spend longer on the rod journals then the mains? I would imagine it is done by "feel" so maybe they felt worse?
if u have the c, shaft in standard can you cut it in to 10 thousands ? in other words can you cut in to the next measurements up using that method ?
no
I hate hand held crank polishers. I prefer dedicated polishers that the belt is located on the rear of the lathe and pivots forward. Much better control of the belt and pressure applied to the belt and crank surface.
I noticed no polishing compound was used.
I would always take a new belt and run it on a old crank and knock the sharp edges off the grit and use a 800 grit compound followed by a 1000 grit compound on another belt. If using Clevite bearings I would step up to 1200 grit polish after the 1000 grit.
Left the crank looking like a smooth mirror. Not one sanding / polishing scratch anywhere.
Polishing a crank is the same as waxing your carrot, it makes a mess and your hands hurt when youre done.
Yea I had one polished and I told them no it is bad. Why can't a shop call you and say no we tried one journal and it need turned easy done. Like I asked them.
Does this increase hp or jus rotate the pistons faster?
Azyatic Both, racers always give their bearings more clearance for less friction.
It's definitely not a polishing, but a grinding.How can you be sure that this grinding is the same on all of the surface of the journal? The belt you're using is twice smaller than the width of the journal....
Question is this what is called micro polished? Or is that more procedures and how much more is it for a micro polish
400 grit def ain’t micro polished, they got crazy sand paper now that goes to like 12k
Is it just me or does 'polishing' with 400 grit seem sketchy. I would think more like a 2000 frit for polishing.
Depends on how bad the surface is
Website does not work.
part 2 see below for part 1...too rough will allow the scratches to score the soft metal of the bearings. Grinding cranks is an art with very close tolerances usually .001" high to low...some even closer at .0005 high to low. Using a new belt at 320 grit can easily remove .0005" from the surface. I always kept used belts as a follow up after initial polish. Too fine of a belt can heat the surface and cause distortions....many people think finer is better...not always true!!!!
I got my crank back and every other scratches
do I need to take it back
is this wilford brimley talking?
Years ago I was sent to Bangladesh to oversee the hand over of a tractor workshop to the government, out of the original 36 tractors only 8 were running, on the day before I went on 2 weeks leave a Ferguson 135 came into the workshop knocking its head off, the mechanic Sheraz came to me and said Mr Roger I know the problem and I will fix it whilst your away. knowing how few spare parts there were and no special tools I told him to strip it but then wait for my return. On my return I walked into the workshop and Sheraz was smiling as he leant on the completed tractor, I told you I could fix it he said so I went to the stores and asked what had Sheraz done whilst I was away to which the store man replied Sheraz had spent 10 days sitting under the tractor with emery paper at which I asked the store man had he got the old big end shells that came out of that engine oh yes he said and gave them to me. The shells edges were razor sharp and the metal backing had turned blue and paper thin. Much to Sheraz's disgust I told him to strip the engine again so I could measure the crank, yes the crank was shiny but it was as oval as an egg.
+rodger stephenson Never trust a Bangladeshi.
WOW great story! gold star for you!
can i polish 1mm layer on cranck shaft?how?
very easily if you let this shyster polish your crank as he is using a very abrasive belt and removing material not polishing if you are actually polishing it is impassible to remove STEEL this guy is using the polish routine to up sell crank cutting because hes in this for a living to make money and people rebuilding engines these days are few and far between
Not at all. I used to work as a polisher for a company who manufactured (from forging a straight bar to finishing) crankshafts for many of the largest locomotive companies in the world. We would FINISH with 240 grit paper. The cranks would come to us with .005" to remove on them and we would start with 80 grit paper and work our way through 100 grit, 120 grit, and finally to 240 grit. The tool he's using we would use sparingly, but our primary tool was a proprietary tool.
The shop I work with goes to 2000grit.
That thing is louder than fuckall.
I polish 16-20 Cyl. locomotive cranks. We use hands and clubs and no power tools like that. i prefer hand polishing compared to that..
doesnt matter if its hand made or with complex tolls, the work must be perfect. Many old sxkool guys do the work perfect, and if you check sometimes is better than with a machine.
I work in a machine shop and we work on big engines like yourself,everything is done "old school" one of our guy's thats now retired did crank work for 30 plus years, guys was super sharp and i would go with him on some crank polishing or cutting jobs sometimes.
We used these polishing blocks, i called them "the man killers", when you were done polishing a journal it was a thing of beauty, i would always ask him, "shit man, why dont you have a machine to do this hard ass work? and he would say , because it wont look like this, ha ha ha ha, in spite of the work i enjoyed going on those jobs, now i just mainly stay in the shop.
if its out of round don't waste your and their time the only fix is to grind under size this is one of those times when the customer is usually not right
oops should have waited to ask how much till the end of video lol
If there is deep pitting rust no way in hell a 2000 grit would ever touch it. 400 grit is fine to start with but you will have to go through your grits as with any polish job. 400-600-1000-1200-2000 is how I'd step it up to make sure its a true polish, just tedious though, then obviously your rouges and buffers.
No you do not put a cross hatch on crankshaft you are trying to polish the crankshaft to a smooth finish.
Is that a vw vr6 crankshaft? Looks like rods ride the same journal is why I'm asking. lol
Would this device be able to do a .010" inch cut?
not a chance.. lol thats work for a grinder
Unless your a machinist, you shouldnt "rebuild" cranks.
He took off close to .002, so if you did it 5 times it would get you in the ballpark. Thats why you mic it.
rutter STFU IDIOT
Yes, if you want barrel shaped journals.
Thats a big crank
That's what she said
What I can't understand is I tell a machine shop- what I want and they don't hear me???? What is wrong with writing it down what the customer wants and calling him and letting him know what it's looking like?
It's funny how many of you "experts" watch how to videos and then tell them how they're doing it wrong.
lol, i have to say i have never seen that many in one single video comment section,wouldn't be surprised if some of the guys that built the Saturn 5 are on here commenting,many wives tales and ways people have to do things different adds to the confusion.
I will take my engines to any one that will do what I want!!!!!!
I wouldn't do it that poorly on a mower engine.
Holy tappers 🙄
You don't cross hatch a crankshaft
End play end play end play end play. Thrust. Everyone checks the bearing surfaces. If the crank end play thrust is out of whack you are wasting your time. It will run but never be right. Never run smooth. Never be entirely properly lubricated. And it will die prematurely.
did you not watch the video long enough to see them polish the thrust bearing surface? a thrust bearing is literally just another main bearing, kind of a given that it would be cleaned along with the rest of the surfaces...not really sure why your implying in your comment that most people just decide to skip that main bearing surface....then I went on your profile and realized your a gamer..explains it all
Ryan James Thats why you call clevite for a wider bearing.
FUCKING IDIOTS!
That is not the correct way to polish a crank. You have absolutely no control of how much material you are removing; Nor do you have any control to maintaining an even surface.
Polishing a crank isn’t just about a “shiny” surface. That crank will not wear the bearings evenly leading to more frequent bearing replacements.
What are you guys doing? What kind of paper you show how to polish the crankshaft is ridiculous you show how to destroy the crankshaft.