Steel on steel - bearing

General engine tech -- Drag Racing to Circle Track

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Kevin Johnson
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Re: Steel on steel - bearing

Post by Kevin Johnson » Sun Oct 14, 2018 9:18 pm

cgarb wrote:
Sun Oct 14, 2018 8:05 pm
Was it an air bearing by chance?
I think with steel that an inert gas would be used. I used to use these in a dental lab to carve porcelain teeth.
gas_bearing.png
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Re: Steel on steel - bearing

Post by modok » Sun Oct 14, 2018 9:26 pm

Circlotron wrote:
Sun Oct 14, 2018 8:32 pm
Hypoid ring gear and pinion (where the pinion shaft is lower than the axle half shafts) have plenty of sliding motion and that's steel on steel. They seem to get along okay. Specific oil though.
Gears are more like flat tappet cam and lifter, in fact you can think of gear teeth as little cams :D
Perhaps a needle roller or ball bearing, is more similar to a gear than a plain bearing.
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Re: Steel on steel - bearing

Post by vwchuck » Mon Oct 15, 2018 2:21 pm

If you want to do steel on steel you better have a PHD in tribology. Why re-invent the wheel. If shit works leave it alone.

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Re: Steel on steel - bearing

Post by noice » Tue Oct 23, 2018 2:19 am

cgarb wrote:
Sun Oct 14, 2018 8:05 pm
Was it an air bearing by chance?
Oil mist lubricated too?

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Re: Steel on steel - bearing

Post by n2omike » Tue Oct 23, 2018 12:45 pm

I opened up an engine someone had free floated the pins on... Never used a bushing on the rod. Had a lot of miles, and wasn't worn. Piston pin against the rod.

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Re: Steel on steel - bearing

Post by midnightbluS10 » Tue Oct 23, 2018 3:49 pm

Truckedup wrote:
Sun Oct 14, 2018 7:43 pm
exhaustgases wrote:
Sun Oct 14, 2018 7:39 pm
So what about iron on iron? I've seen that a lot. And steel on iron as well.
Yeah, Ford N tractors ran the cam directly on the cast iron block..I believe the cam was cast, but not 100 % sure...On some manual transmissions, gears may spin on shafts with no bushings or needle bearings
GM's 4.2L I6 in the Trailblazers/Envoys runs the cams straight on the aluminum head with aluminum hold down caps, also. No bearings anywhere. Something I'm glad I didn't have to get into when the local machine shop overtorqued the caps so badly the cams barely turned. I knew something was up when the cam didn't roll over itself once I got over the nose from spring pressure. It just stayed there.

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Re: Steel on steel - bearing

Post by jsgarage » Tue Oct 23, 2018 4:27 pm

Had the exact same thing with a Harbor Freight compressor on which a flex hose blew off late one night so the poor thing tried to refill its 60 gallon tank all night & overheated. I looked at the no-oil-pump design and made a new con-rod out of scrap 7075 aluminum. Took about 1/2 hr and that was 4 years ago. My best guess- don't screw around with steel on steel when its so easy to dup' the rod in other materials; if I'd had a chunk of bronze, I'd have used that.

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Re: Steel on steel - bearing

Post by governor » Tue Oct 23, 2018 6:01 pm

If you could ceramic coat the rod or apply a DLC coating you might get buy, how about an bronze busing

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Re: Steel on steel - bearing

Post by pamotorman » Tue Oct 23, 2018 7:01 pm

don't forget ball and roller bearings are steel on steel. with proper design and lube it works well

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Re: Steel on steel - bearing

Post by hoodeng » Tue Oct 23, 2018 8:22 pm

Ball and roller element bearings are friction-less bearings ,journal bearings are passing surface bearings for lack of a better description and need constant supply lubrication.

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Re: Steel on steel - bearing

Post by pamotorman » Tue Oct 23, 2018 8:35 pm

could it be that plain bearing cranks are a cheaper way to do crank journals. porsche built engines with roller bearing cranks and motorcycles also had roller bearing crank journals

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Re: Steel on steel - bearing

Post by Momus » Wed Oct 24, 2018 4:55 am

Circlotron wrote:
Sun Oct 14, 2018 5:53 am
Not quite an engine but the similarities are obvious.
A friend has a cheap, nasty and quite small air compressor that has an aluminum conrod with no bearing shells, just conrod running directly on the journal. When he first got it given to him free it had a huge big end knock. Eventually we found a replacement rod and all was well. The crank journal is about 1/2" diameter and was still smooth. If it quits again I am considering making a steel rod for it. Balanced be damned!

Is there any issue regarding running the steel rod on a steel crank pin provided the surfaces are sufficiently smooth to begin with?probably no issues.
Motorcycle rods and pins are almost all steel to steel and the same grade as well.

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Re: Steel on steel - bearing

Post by peejay » Wed Oct 24, 2018 7:03 am

Truckedup wrote:
Sun Oct 14, 2018 7:43 pm
exhaustgases wrote:
Sun Oct 14, 2018 7:39 pm
So what about iron on iron? I've seen that a lot. And steel on iron as well.
Yeah, Ford N tractors ran the cam directly on the cast iron block..I believe the cam was cast, but not 100 % sure...On some manual transmissions, gears may spin on shafts with no bushings or needle bearings
Triumph sixes did this too. It didn't work very well long-term. One of my friends had one where the cam dug itself so deep into the block that the hole was still egg-shaped after boring it out to take press-in bearings.

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Re: Steel on steel - bearing

Post by peejay » Wed Oct 24, 2018 7:06 am

midnightbluS10 wrote:
Tue Oct 23, 2018 3:49 pm
Truckedup wrote:
Sun Oct 14, 2018 7:43 pm
exhaustgases wrote:
Sun Oct 14, 2018 7:39 pm
So what about iron on iron? I've seen that a lot. And steel on iron as well.
Yeah, Ford N tractors ran the cam directly on the cast iron block..I believe the cam was cast, but not 100 % sure...On some manual transmissions, gears may spin on shafts with no bushings or needle bearings
GM's 4.2L I6 in the Trailblazers/Envoys runs the cams straight on the aluminum head with aluminum hold down caps, also. No bearings anywhere. Something I'm glad I didn't have to get into when the local machine shop overtorqued the caps so badly the cams barely turned. I knew something was up when the cam didn't roll over itself once I got over the nose from spring pressure. It just stayed there.
I have yet to see any OHC engine with an aluminum head and separate cam bearings. They always ride directly on the aluminum. The spring loads are very low so this is not a problem.

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