Frigidaire Unimatic Oil Pump Seals - explained

[sfh074]

If you are worried ....

about a dry top spin bearing, could you use a sealed bearing alternative?

 

I used this sealed top spin bearing in place of the original open style on my multimatic rebuilds. Have done 5 this way so far and they have worked out great. They are totally water resistant, permanently greased with synthetic bearing grease that is non-hydroscopic and never dry out.  No oil is needed above the bearing on anything in the uni just like the multimatic . The multimatic simply relied on splash lubrication to oil this original bearing ..... and it is much further up the housing than a uni design. I say this because I wonder WHY they went from a positive pressure oiling design on the uni ..... to a splash oil design on the multimatics. The stresses are the same, but maybe they figured the old design and all that oil was just not needed? 

 

Below is a picture of the sealed bearing I used in my multi rebuilds.

 

[swestoyz]

Sealed bearing alternative?

Great minds think alike

This thought has crossed my mind before as well. The problem then becomes - what to do with all that pumped oil? It would pool on top of the rubber seal in the housing neck with nowhere to go/drain back down to the mechanism base.

The top hole on the spin cage shaft could technically be plugged, as there is a hole above the bearing and one just below the washer that provides lubrication to the rotating mechanism just below in the spin cage. While the intent is good it's probably not worth it. GM wisely submerged the rotating mechanism in oil within the Multimatic, relying then on splash lubrication to throw oil up through to the bottom bearing on the mechanism housing support, as well as the pulsator shaft.

John and Robert have a good point about the top bearing on a Unimatic, however I like to err on the side of caution to ensure that the bearing does have enough lubrication to avoid any unnecessary stress, even if it is only to relieve stress in my mind.

Ben

 

[combo52]

Fun Thread

While it is certainly true that the UM oil pumps will not pump much oil till the motor has reached full 1140 RPM speed, it only takes 10 or 15 seconds to reach full spin speed, no bearing damage would occur in that time.

 

The UM mechanism with its own oil pump forces oil through out the inside to all bearings, the agitation operation does not help assist the oil flow, in fact less oil would flow to the top bearing while agitating because when it is agitating more oil will escape out of the moving bushings.

 

The pressure oil system was over built and considering washing machines have no where near the stresses an internal combustion engine in think the engineers decided the splash system was more than sufficient for long life in the later Multimatic mechanisms, in my experience the MMMs out lasted the UMMs and certainly had less problems.

 

Hi Bud those new sealed bearings are really good, however they still not take water & detergent for long, I suppose you could try leaving out the main water seal but I can assure you the machine won't run a year with those bearings exposed to water etc.

 

John L.

 

[gyrafoam]

Years ago------

I was delighted to find an old Flat-Top with a low production-run number.
No telling how many decades it sat idle gathering dust until I came along.
Cosmetically it was in great shape and appeared to be low-mileage.

While I did have the forethought to run some hot water down it's hose and into the pump for an hours soak, I did not think-out the possibilities of a lubrication issue. So in my zeal to find out if it worked I advanced the timer through the fill and into Pulsation. Since it Pulsated without the tub turning, the next step was into spin. At the same moment I heard the trip-switch engage the thought occured to me that there might not be a drop of oil in it. By then it had been ten seconds or so, but, I shut it down anyway. The instant I did the whole machine seized-up and turned itself a half-turn on the floor nearly knocking me down in the process. (A Unimatic with an empty tub can get up to a pretty good speed in about ten seconds!)

In disgust I set it aside. I knew whatever the problem was, it would be a shlep to repair. A few years later and I decided to tinker with it and started to tear it down. As soon as I got the tub out I saw that the Tub-Support Mechanism had been torn in two. It was brittle almost like glass. So once again, in disgust, I walked-away. It still rests down in Triage awaiting assistance.

Lubrication may or may not have been the problem, but, someone would have a hard time convincing me that allowing it to Pulsate for ten minutes or so with the oil moving around might not have made a big difference in the outcome of my little spin-test.

 

[swestoyz]

John, I agree with part of your thinking in that the likelihood of bearing damage occurring on a rebuilt/reoperated mechanism would be slim if activating spin when the machine has been idle for a bit of time. While I wouldn't considering it babying the machine, if I can at least help the bearing out by getting oil up to the bearing before spin I will continue this practice and will continue to suggest the same to others.

What I would like to be clear on is the oiling system does supply plenty of oil to the top bearing, regardless if it is in agitation/pulsation, or spin. The photos and video within response 19 provide enough evidence for me to feel comfortable with this as fact; both the still shot and video were taken with the machine pulsating with an original style pump.

This would also be taking into account your hypothesis of oil pushing past the rubbing surfaces of the rotating mechanism during agitation, and still the pump is pushing enough volume of oil through this entire oiling system (orange is pressure/blue is passive return to the mechanism base). Is it over built? Absolutely. Is it definitely built by a car company? Absolutely. Is the mechanism less reliable due to it having a pressurized oiling system? Possibly - if we consider the idea that it can/will leak past the mechanical seal/or fail due to a broken finger.

GM did the right thing by ultimately moving to the Pulsamatic/Multimatic mechanism, outside of the early clutch fiasco, but it does leave some wonder of why they didn't go ahead and have all commercial machines start with the Multimatic mechanism staring in 1959.

Ben