Plastic cage bearings?

[mercrazy]

What rpm is safe for these?
I’ve torn down a lot of blown engines and have never seen a failed plastic caged bearing. I’ve seen several bad metal caged bearings. None of these engines were all out race engines. Are plastic caged safe at 7000 rpm?

[tlwjkw]

seen a lotta $hit fail over tha years but never a rod bearing (primary cause) of "either" type... jmo

tha merc scientist seemed ok with 'em ina a lotta motors, includin' tha PM's............

[Chaz]

I've got no dog in the 2.5L fight, but I think it's a case of the bean counters winning out over the engineers on this one.

Is it just a wife's tail .. that every time someone ask's about doing a rebuild .. that they get pointed to doing the metal caged bearings .. ???

[tlwjkw]

Is it just a wife's tail .. that every time someone ask's about doing a rebuild .. that they get pointed to doing the metal caged bearings .. ???

....

[David - WI]

Interesting thing...

Non-metallic bearing cage materials are mainly polymers and their composite materials, including nylon, phenolic adhesive, PTFE and so on. Polymer materials have good strength and elastic matching. The good sliding properties allow the polymer cage to generate only a small amount of friction when it is brought into relative motion with the surface of the lubricated rolling element, which minimizes heating and wear of the bearing. In the absence of lubricant, polymer cages still have excellent kinematic properties. It can be assured that the bearing will continue to run for a while without damage. Due to the lower density of the polymer, the cage made therefrom has less inertia.

[rock]

Never seen one fail and have used a bunch of them.

Rock

[pcrussell50]

Never seen one fail and have used a bunch of them.

Rock

Do you replace them automatically during a rebuild? Or do you re-use them if they still look good?

I’ll be replacing a the top two pistons on a stock 2.0/150 fishmotor. It will remain a stock fishmotor.

-Peter

[pcrussell50]

Never seen one fail and have used a bunch of them.

Rock

Do you replace them automatically during a rebuild? Or do you re-use them if they still look good?

I’ll be replacing a the top two pistons on a stock 2.0/150 fishmotor. It will remain a stock fishmotor.

-Peter

[LakeFever]

Certainly a lot of suggestions against them out there but I haven’t owned enough of these yet to see a problem. . Same as the oil injection delete which is highly suggested. I was advised, ignored and paid the price. The engine had sat fogged for a few years. Old school engine builder says it’s the fogging fluid that softens the oil gear and causes the issue. Maybe it’s the fogged motors having issues with the plastic cage bearings?

It’s worth a thought or two maybe. I’m on 65 hours of high rpm on my metal rod bearings. So far so good

[tlwjkw]

if it softens tha oiler gear "plastic" then don't ya think it would do tha same to tha bearin' plastic???.. 8 ta 10 grand plus stem winder motors then yeah.. can see tha metal but plain 'ole production motors really no reason for metal ta me... i can't recall one thread on this site where tha plastic was ta blame for a failure... but i'm pretty old soooooooooooooooo.

[skialot2]

One of the motors i picked up last year came with a powerhead that had thrown a bearing. Some how, someway, a rod bearing came out of the rod with the rod still in one piece. The rod cap was still attached to the rod. A little banged around but not really deformed. Both bolts still tight. Plastic cage must have disintegrated. I still cant figure out how all the needles got out from between the rod and crank but I found no remains except one roller wedged between the piston and the sleeve. I don't think that could happen with metal cages. But who knows.

[tlwjkw]

not sayin' it can't/doesn't happen jus think its way overstated as a problem.. seems ta me if one let go it would be total destruction with everything in that hole includin' tha head.... jmo

[David - WI]

not sayin' it can't/doesn't happen jus think its way overstated as a problem.. seems ta me if one let go it would be total destruction with everything in that hole includin' tha head.... jmo

Yeah, my buddy just traded his 30 year old 2L (with a plastic oil-injection gear) in for a four-sroke after it blew a head gasket... he said he wanted something more reliable.

I asked how many times the 2L broke down... he said, "Just this one time."

We won't probably live to see 30 years on the four-stroke but I bet we'll live to see it break down more than once in first 15 years!

[skialot2]

seems ta me if one let go it would be total destruction with everything in that hole includin' tha head.... jmo

Yep. Everything was destroyed. Piston, sleeve, rod and crank were junk. Head was peppered. Front half had a slight crack from the rod banging it.

[rock]

Do you replace them automatically during a rebuild? Or do you re-use them if they still look good?

I’ll be replacing a the top two pistons on a stock 2.0/150 fishmotor. It will remain a stock fishmotor.

-Peter

As long as they look correct, I re-use them.

Rock