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SGKent 
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Joined: October 30, 2007
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 Posted: Fri Sep 04, 2009 9:16 pm Post subject: mahle vs KS cam bearings end play variations-Opinions needed |
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Type 4 motor, street and long distance trips planned
Building the motor this weekend
Cam end play with KS copper thrust is .004
Cam end play with Mahle babbit thrust is .002
New is supposed to be .0016 to .005. Wear limit .006
Which would you use? I would like to use the KS but I am a little concerned about the greater endplay. I mic'd the bearings to see where the difference is and it is in the thickness of the actual thrust area. So.... I am thinking the Mahle is a better gamble as it has to wear .002 just to get to where the KS are now - by then the KS will be at .005 I figure.
T4 engine builders - what do you think?
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SGKent
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| Posted: Sat Sep 05, 2009 6:00 pm Post subject: |
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well, I guess no one here knows. Mahle it will be.
reasons:
correct end play
chamfered oil hole
I've heard good things
noticed that JR had Mahle's on the Bugme video a friend lent me
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miniman82
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| Posted: Sun Sep 06, 2009 2:07 pm Post subject: |
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You know you can wet sand the thrust on tight bearings until they give the correct endplay, right? I've had to do that on every engine I build, as I find the Mahle ones are a little on the tight side.
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| satterley_sr wrote: |
I just wanted to bitch but I'm getting no sympathy. |
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SGKent
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| Posted: Sun Sep 06, 2009 4:53 pm Post subject: |
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gee, but one can't sand them to lower too mcuh freeplay. The KS were .001 shy from being too much freeplay and the Mahle were dead on. The KS is supposed to be a better bearing with the copper thrust but if they are too loose then that doesn't work either.
We used the Mahle and the case is now buttoned up.
Also WARNING from a friend, a professional grinder from the aero-space industry, who taught me a little about grinding. Sanding a soft material like a bearing can be problematic. The soft material picks up the loose abrasives and it then becomes a cutting stone. What would be better is to use a babbit knife or even a pocket knife with a flat blade to gently scrape them until they fit.
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miniman82
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Joined: March 22, 2005
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| Posted: Mon Sep 07, 2009 9:03 pm Post subject: |
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| SGKent wrote: |
| Also WARNING from a friend, a professional grinder from the aero-space industry, who taught me a little about grinding. Sanding a soft material like a bearing can be problematic. The soft material picks up the loose abrasives and it then becomes a cutting stone. What would be better is to use a babbit knife or even a pocket knife with a flat blade to gently scrape them until they fit. |
You should take what your friend says with a large helping of salt. Sometimes things that apply to the Aerospace industry sound stupid when you apply them to automotive hobbies. For example, the whole reason there's a soft babbit in bearings is so that if something does get into the bearing, it will get embedded in the soft metal instead of sliding around and around doing damage to the journal.
Scaping a bearing with a pocketknife is also a very bad idea, there's almost no way to make sure you remove the same amount of material consistantly. That's why you wet sand with fine grit paper, so the bearing will still be square. Everyone I know does it this way, I dare say it's standard practice. For what it's worth, even if some grit from the paper does get stuck in the bearing thrust, it won't stand a chance against the hard cast iron of the camshaft.
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| Glenn wrote: |
| satterley_sr wrote: |
I just wanted to bitch but I'm getting no sympathy. |
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Sigurd
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Location: Rockford, IL
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| Posted: Tue Sep 08, 2009 6:41 am Post subject: |
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I second that. I had to wet-sand about 0.003" off my cam thrust bearing. I would never use or recommend something as imprecise as a knife to set a bearing clearance. You have no way of keeping the surface flat and you have no way of being anywhere close to uniform.
Last edited by Sigurd on Tue Sep 08, 2009 9:05 am; edited 1 time in total |
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SGKent
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| Posted: Tue Sep 08, 2009 8:06 am Post subject: |
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| Quote: |
| Scaping a bearing with a pocketknife is also a very bad idea, there's almost no way to make sure you remove the same amount of material consistantly. That's why you wet sand with fine grit paper, so the bearing will still be square. Everyone I know does it this way, I dare say it's standard practice. For what it's worth, even if some grit from the paper does get stuck in the bearing thrust, it won't stand a chance against the hard cast iron of the camshaft |
I spent many years working for a shop that built engines for Indy teams. You need to learn how to scrap a bearing to increase clearance. The best tool is a 3 edged babbitt knife. You also need some dye or a magic marker to find high spots. As for my friend, I didn't want to go into a disertation on all the things he builds parts for including air cooled aircraft engines.
The hard pieces of grit will scratch the crankshaft. What do you think they polish it with?
Let's have a test of whether you are right or I am right. Thin (sand) a stick of cold butter with pieces of sharp broken glass glued to a piece of cardboard. As the pieces of glass come loose they will get stuck into the butter. Now run your hand across the butter and tell me if you have cuts on on your hand or if the glass magically buried itself so deep it couldn't cut you.
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miniman82
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| Posted: Tue Sep 08, 2009 8:32 am Post subject: |
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Or how about a real life situation: ALL MY ENGINES ARE BUILT THIS WAY. None of them are breaking down, and neither are anyone else's that wet sand their bearings. If you want to worry about every microscopic peice of crud that gets into your engine you'd never sleep at night- guess what? There's all kinds of shite inside engines ALL THE TIME! A few peices of aluminum oxide isn't going to kill it, and it's not like you sand and install. You clean everything very well, then assemble.
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| Glenn wrote: |
| satterley_sr wrote: |
I just wanted to bitch but I'm getting no sympathy. |
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Sigurd
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| Posted: Tue Sep 08, 2009 9:08 am Post subject: |
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| Any microscopic particles that remain and then make their way through the 0.003" oil pump clearance that I have will be filtered out by the filter. |
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SGKent
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| Posted: Tue Sep 08, 2009 9:20 am Post subject: |
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I've never in my life seen so many mule headed people in one place. Believe the world is flat too if you wish.
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Viande
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Sigurd
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| Posted: Tue Sep 08, 2009 10:25 am Post subject: |
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So where do we draw the line? Oil pump bodies and gears get sanded for zero clearance. Pump covers get sanded flat. Cylinders get lapped to the case. Cylinders get lapped to the heads. I had to wetsand the distributor drive slot so the shaft would slide in and turn after I drilled out the galley plug next to it. All these operations generate grit. Did you knife the tops of your cylinders? Did they seal?
And as long as we're taking analogies completely out of context, scrape that knife across the stick of butter and see how many high spots you leave. Is the top surface of the butter parallel to the table you cut it on? How many times did the knife dig in?
Even with the dye, how do you know how much you took off? Great. You scraped the dye off. Half a thou here, 6 there. Whatever, the dye's gone! Must be flat! |
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miniman82
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| Posted: Tue Sep 08, 2009 12:55 pm Post subject: |
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This is getting blown way out of propotion.
They only way to have a perfectly clean engine, is to assemble it in a clean room. Guess how many people have access to one of those? Fact remains- you won't do any damage to the cam bearings by wet sanding them, and the sanded bearings won't do anything to the hard iron camshaft. You probably create more grit from breaking in the cam and rings anyway, ever seen what the oil looks like after break in? It's not clean at all, and I don't care how careful you are about keeping stuff out of it during assembly. I'm not telling you to stop worrying about being clean with building, but you can take it to far.
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| Glenn wrote: |
| satterley_sr wrote: |
I just wanted to bitch but I'm getting no sympathy. |
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Randy in Maine
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| Posted: Tue Sep 08, 2009 1:05 pm Post subject: |
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More importantly, how is the split bearing fitting?
Is it keeping the case from being correctly tightened up? |
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Jake Raby
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| Posted: Tue Sep 08, 2009 2:24 pm Post subject: |
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Before you grind or remove material.
Install the bearings into the case and then install the camshaft..
Tap the cam fore and aft end to end using a soft piece of wood or a brass drift and use some force..
Do this 4-5 times back and forth and then check your end play.
Report back with what you find. (I already know)
Then you'll see what happens IF you had removed the material required to gain the clearance...
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Jake Raby
Raby Engine Development
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"I've never given anyone Hell, I just told them the truth and they thought it was Hell" |
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SGKent
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Location: at the beach
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| Posted: Tue Sep 08, 2009 4:23 pm Post subject: |
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Hi Jake - Engine is together so I can't smack it without tearing it back down however the I tapped the front and back a little when installing it. The KS were .004 with light pressure in each direction and the Mahle were .002. The Mahle also were a tighter fit in the thrust area of the case where the KS were looser. I also noticed the KS had no chamfer on the hole whereas the Mahle have a small chamfer on the hole. Mahle looks to be a harder material whereas the KS look like the older babbit material.
Steve
Re Sigurd question on sanding pumps etc :
| Quote: |
| Oil pump bodies and gears get sanded for zero clearance. Pump covers get sanded flat. |
Those are hardened steel and alloy aluminum. It is Ok to polish those. They are hard enough to reject the embedding of the grit. I spoke only of sanding bearing material which is a very soft material and it will pick up pieces of grit and then slowly grind away at the journals.
Re Miniman82 clean room comment: Before I assemble an engine I clean the garage (it is drywalled) and use a leaf blower to blow out as much dust as I can. I mop the floor. Everything around my work area is wiped down or old towels / sheets that have been dried in the dryer with fabric softener are laid down. The workbench top is smooth masonite. Some benches in the past have been stainless steel as it is easy to clean. Then I build the engine and use compressed air outside to clean parts. Get used to rubbing your fingers together as they will tell you when they are dirty. During a motor build I probably wash my hands 20 times or more. Did you notice how clean Jake's hands were when he assembled the motor in his bugme video? Several times he wipes his fingers and feels a bearing or part for any imprefection or even lint. You don't have to own a clean room to build a clean engine. Shops that have a clean room often do that because they have other things going on that create dust - glass beading, grinding etc. Good practices are what you want to strive for. Example - Jake suggested I load the cam in both directions before measuring clearance. That is a good practice I have now added to my list of practices on the next motor.
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miniman82
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| Posted: Tue Sep 08, 2009 7:26 pm Post subject: |
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Correcting for cam endfloat by wet sanding does not do damage to engines, period.
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Build thread: http://www.thesamba.com/vw/forum/viewtopic.php?t=212747
| Glenn wrote: |
| satterley_sr wrote: |
I just wanted to bitch but I'm getting no sympathy. |
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Jake Raby
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Location: Aircooled Heaven USA
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| Posted: Tue Sep 08, 2009 7:57 pm Post subject: |
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| miniman82 wrote: |
| Correcting for cam endfloat by wet sanding does not do damage to engines, period. |
Except when the material is removed for absolutely no reason...
Which is what you'll find IF you seat the bearings into the case with the practice I outlined above. I see cam bearings of any manufacture that have as little as .001 or even zero clearance end up with a perfect .002-.003 after simply being seated into the case. I probably haven't removed material from a cam bearing in at least 5 years.
In 20,000 miles when a small noise pops up at idle speed and you find that you have thrust bearing wear you'll understand.. Maybe after 20-30 engines having that noise and having accelerated thrust bearing wear you'll understand that I was right.
Remember, you haven't built a TIV engine yet. I'd refrain from making such bold statements until I had at least one under my belt- but thats just me.
As for being clean, you can never be clean enough.. In the video I didn't shoot it in the clean room and I didn't use practices that those doing the job at home would not be able to comply to.. I didn't use crazy practices because I didn't want to scare people by making them think that you **had** to have these areas- just good practices and cleanliness.
But when I assemble an engine I clean the entire room top to bottom before the parts are introduced into the environment (clean). Here is one working area, notice that I am assembling an engine while these pics were taken.
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Jake Raby
Raby Engine Development
www.rabyenginedevelopment.com
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miniman82
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| Posted: Tue Sep 08, 2009 11:11 pm Post subject: |
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| Jake Raby wrote: |
| Remember, you haven't built a TIV engine yet. |
Doesn't matter, they both use the same exact cam bearing setup. Matter of fact, I'm using T1 double thrust bearings in mine. It's not my first shindig.
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| Glenn wrote: |
| satterley_sr wrote: |
I just wanted to bitch but I'm getting no sympathy. |
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SGKent
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| Posted: Tue Sep 08, 2009 11:33 pm Post subject: |
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Jake - that is one of the nicest assembly rooms that I have seen. All the more reason that people should consider your services when it comes time to build a new T4.
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