Saving a Unimatic - a Custom Imperial restoration

[swestoyz]

Hey gang - it's been a long time since I've had an open window of time to post something in the Imperial forum, and I'm excited to share with everyone a project that I worked on between August of this year, through the fall.

About 5 years ago a 1958 Frigidaire Custom Imperial set came to live in Iowa, after living with John and Tom for quite sometime, while the Maytag combo went to live in the Beltsville museum.

The story I was told was that the washer was found while Tom was driving along the interstate in Atlanta and spotted the 'Ultra Clean' on a loading dock. I too would have been shocked to see such a sight while driving!

Eventually the transmission made its way to Minneapolis for a reopperation, and from there it served Tom for several years and went to live in the museum.

Knowing that not everything is going to come blemish free and in tip top operating condition, the washer appeared to not have been used in quite sometime and had a fatal issue - spin (with a roaring upper spin bearing), but no pulsation. At the time it was best to push the set in the corner and wait for a rainy day/different season in life.



Between the summer of 2014 and now I even debated selling the set but decided to hold on to it, and since then I've gotten married, moved (outside of the house, one 18' U-Haul truck handled the whole collection) , had a daughter, and everything else that comes along with the typical American dream.

The set, back in 2014:

 

[swestoyz]

A few years ago the first spark to light the fire to restore the washer came from a partnership with Bud (Sfh074). I had supplied him with several rubber Frigidaire items, including a mint 5432199 pulsator and the dispenser cap from the '58. We've all seem the fruits from Bud's efforts over the last few years as he magically recreated the soft rubber parts, making new items that were not only soft and pliable, but also the correct colors. His efforts will allow us to take restorations to the next level.

The second spark came this summer, when I had planned to visit Jetaction and our webmaster in Minneapolis. Ahead of this trip I decided to pull the mechanism so I could take the housing to Robert's to extract the upper spin bearing. From the get-go I knew things weren't great.

Rust covered the pulsator shaft, long with rust inside the upper spin bearing and coating the bushing and spacer. Signs of water and rust were also evident inside the mechanism support seal.

Also, I was surprised to see this mechanism had been outfitted with a replacement Delco motor from 1976, and a modified mount for a compressor style capacitor. It was also missing the trip solenoid terminal shield (oil pan under the solenoid).[this post was last edited: 12/28/2019-20:32]

 

[swestoyz]

Well, the next step to getting the housing off was to drain the oil. When I was growing up I was often found in the garage helping my Dad work on his drag car, and when you pulled the oil pan plug to find this, he always called it a chocolate milk shake - something you definitely don't want to find.

Water had mixed with the oil, and mostly water was left. The spin cage and base were seized solid and rust was lining the inside of the housing.

 

[swestoyz]

While visiting with Robert and extracting the bearing from the housing, the balance of the parts were soaking in mineral spirits. First and second round of cleaning actually went pretty well and all parts from the spin cage/base assembly came apart without too much hassle.

Date code on the base is early 1958, and the mechanism base is late '57:

 

[swestoyz]

The first item tackled during the reopperation was the spin cage and base assembly.

Out of all the various service manuals I've come across from reopperating Unimatics, the 1961 commercial manual Robert has posted on AE.org is by far the best for general use of reopperation. The '58 manual is also really good and covers small changes that happened through the years.

Both manuals clearly it clearly walk through the assembly of the base assembly and which pin requires staking. All clearances checked out to be within tolerance (on the low side, too!).

As for the bolts that secure the cage to the base I decided to use a dab of Locktite as some added insurance.

Pro tip - spend as much time as you can on cleaning out the oil passages on these parts. They need to be perfectly clean - use compressed air and small bristle brushes to make sure no debris is left behind. In my case, there was a lot of sludge left over even after two rounds of cleaning with mineral spirits.

Can anyone spy what I assembled backwards?[this post was last edited: 12/28/2019-20:38]

 

[swestoyz]

The next leg of the restoration became more of an exploration of the mechanism seal. It is widely known that the '57 and '58 Unimatic features a redesigned seal assembly (5879002), featuring a smaller mechanism nut and a new mechanical face seal, differing from the previous '47 through '56 lip seal and larger nut.

What isn't as widely known is that the top seal of the 57/58 Unimatic is the same mechanical face seal as the late 1955 thru 1958 Pulsamatic, which then is the same seal for the '59 through '64 Multimatics, AS WELL as the Rollermatics up through 1969! Yes the nut part of the assembly is unique to the Unimatic, but you can pop out the mechanical seal and replace it with a new 5439025 seal.

In the early 70's GM sub'd out the 5439025 seal on the Rollermatics to the updated 633626 seal, making that seal backwards compatible back to the Pulsamatics and Unimatics! The bronze seal assembly on the bottom side of the tub remained the same for late ‘55 thru ‘58 Pulsamatics, 57/58 Unimatics, up to the end of the solid tub Rollermatics in 1969.

First picture below - on the left is a Unimatic seal nut with a 5439025 seal set in place, and the original seal that was on the Custom Imperial.[this post was last edited: 12/28/2019-20:41]

 

[swestoyz]

While on the seal discovery path, parallel to those efforts I was getting the last of the parts disassembled and cleaned. I'm still shocked that the motor ran at all with the amount of oil coating the start switch terminals. Sheesh!

Also, it was at this time that I discovered that the torque plate was damaged. In the photos I've staged the torque spring and hub to sit inside the plate. The second shot you can see the broken part of the plate where the torque spring is able to twist into the plate. In '58 GM redesigned the plate with larger openings, of which I suspect was to allow for better oiling of the torque spring.

It's amazing that this machine would still stop the tub after spin, considering the glazed condition of the brake pad on each plate.

And, yes, that is oil coating everything within the motor. While the windings weren't soaked, everything else was.[this post was last edited: 12/28/2019-20:42]

 

[swestoyz]

Thankfully over the years I've found a fair amount of Unimatic parts, with one now critical part being a hub kit (5876907), which included a new hub plate and hub. I also had found one brake plate (5430571) and happened to find a second NOS plate during the restoration.

One critical measure the reopperating manual documents is the clearance between drive shaft sleeve and the torque plate, spec'd to be between .003 and .012. I don't have a picture of the feeler gauge in place, but in the first shot the gap is about .030! That isn't going to work at all, and may be the reason why the torque plate had a broken finger in the first place. Unfortunately the drive shaft diameter and collar diameter are not 'standard' to different industry thrust washers, leaving any over the counter generic option off the table.

I reached out to Robert and he happened to have an extra thrust washer (.025, 5433461) that I could use. With the thrust washer in place the clearance came out to .005. Almost perfect![this post was last edited: 12/28/2019-20:45]

 

[swestoyz]

Speaking of reading the reopperating manual carefully...

While reading up on the spacing in the previous post, I stumbled upon a mistake I made when assembling the spin cage/base assembly earlier (first photo). I had gotten the oiling hole orientation backwards, which would have caused the upper spin bearing to not receive any oil! I'm so glad I caught this when I did.

Also - a must have tool to add to your Unimatic arsenal is a pair of Vacuum Grip 70-B pliers. These work PERFECT for removing the rings that hold the trunnion on place. GE also recommends using these to install the brake bands in the '56 through '59 solid tub transmissions.

I used the snap ring pliers to reinstall the rings (and be careful you don't stab yourself when doing so...)[this post was last edited: 12/28/2019-20:47]

 

[swestoyz]

At this point I was getting ready for the full reassembly and needed to button up the NOS hub plate/brake assembly. Each brake plate had a layer of oil added to each brake pad prior to assembly. I also re-used the 1958 style pins and springs but used new cotter pins from the hardware store to hold everything together.

To assemble, use a 2x4 on the floor to press down on each pin/spring to get the cotter pins to slide through the back side.

New assembly on the left, old on the right.

 

[swestoyz]

With the hub/brake assembly taken care of it was time to assemble the rest of the mechanism, starting with the oil pump. Take two small 2x4 and place the mechanism base upside down, and insert the bronze thrust bearing and drive shaft. I lubricated both with air compressor oil prior to installing.

This particular mechanism had the upgraded oil pump from the mid 60's, which includes a revised mechanical seal placed on the bottom of the pump housing and a new spring loaded plunger style pump, vs the early style finger pump.

Rather than reuse the original gaskets and o-rings I opted to make new cork gaskets where needed, and procured properly sized o-rings for both the oil pump and trip shaft. Another issue I ran across was the cork gaskets supplied in the oil pump kit shrank considerably from its original form, which mirrors what I've seen with the cork gaskets for various pump housings as well. Thankfully all cork gaskets on a Unimatic are round are pretty easy to cut and I highly recommend getting a punch set to knock out the correct size holes.

For the 6591693 oil pump kit, use these o-rings. I'll eventually do a write-up on the differences between the two oil pumps with the industry numbers for both versions.

Large 7529598 - industry number 213 (Grainger 41UK89)
Small 7529595 - industry number 115 (Grainger 41UK13)

The revised oil pump directions are not printed in any of the reopperating manuals, so I've included it here.

 

[swestoyz]

With the rotor in place it's time to slip the motor case over the rotor and onto the mechanism base. Align the trip solenoid with the trip. Prior to installing the motor base I'd recommend checking the bearing. This one was locked up and required quite a bit of oil and motivation to get back on track. Also make sure to replace any spacers that may have been installed between the rotor and motor housing and make sure the start slider for the start switch moves freely and install the start switch. Both screws have different shoulder lengths so make sure you keep track of which screw goes where (tall shoulder goes towards the outside).

I used a Craftsman impact driver to install the screws for the motor cover - if you don't have one this is a MUST have for both assembly and disassembly of many fasteners we deal with. The motor housing will make an audible snap once it's been properly seated. With the screws torqued down it's time to install the motor fan. If there is any slop between the shaft and the fan you may end up with a rattly fan during operation.

 

[swestoyz]

Next up - pump housing. Both the bronze and carbon seal were in great shape so I reused both. All flaky residue was cleaned off with a wire bush on a motor. Add a dab of RTV to the bottom of the bellows seal and put a coat of compressor oil on the seal face using a cloth (not your finger). I use Locktite for the impeller screw and the impact driver again to install the impeller screw with a single screw installed in the housing and a screw driver holding the fan stable.

A new cork gasket was cut and and punched with RTV installed on the cover side, dry on the housing side. Prior to installation buff both sides on a wire wheel, if possible. This will also help during the final installation when installing the mechanism on the snubber.

Align the X on the backside of the cover with the trip shaft and torque down the screws.

After about an hour I came back and rechecked all screws.

Pro tip - you may notice that all the fasteners are shiny but not new. Take the time to clean all screws on a wire wheel and taped holes with a tap. This will help ease the reassembly and ensure that all fasteners are torqued down without debris interfering with the fastener. [this post was last edited: 12/28/2019-23:11]

 

[swestoyz]

At this point everything has been reassembled from the base down to the pump. Now it's time to flip the assembly over to finish the top side.

I didn't document with photos the installation of the trip shaft and oil plug, but I did install a new o-ring for the trip shaft. In '58 they revised the trip shaft to have an o-ring seal from the trip shaft bore, rather than on the outside of the base. You can use a '58 trip shaft in all earlier bases if you happen to have a spare on hand. I haven't taken apart an earlier version yet to see how this seal is put together to understand if we can replace those seals with newer parts, yet.

1958 Trip Shaft seal o-ring 5929144: industry number 010 (Grainger 1KET3)

For the oil plug you can more than likely reuse the seal, but I went to the hardware store and found a replacement.

Moving on - the NOS torque spring and NOS hub are now installed on the drive shaft. I'd recommend putting oil on all surfaces to ease in installation. You'll want to twist it as you push it down in order for everything to seat properly. Next, install the hub plate/brake assembly over the torque spring hub, aligning the fingers of the spring inside the hub.

Next, install the trust washer spacer (as needed, in this case I desperately needed one), the collar, pin, and pin retainer.

Pro Tip - make sure the oil passages in the drive shaft are also clear of any debris or sludge. We need to make sure those upper spin bearings are lubricated properly.
[this post was last edited: 12/28/2019-23:14]

 

[swestoyz]

Now the spin cage/base is reunited with the mechanism! The reopperating manual shows the use of a spacer tool to ensure that the cage is aligned and doesn't damage the drive shaft during installation. Take caution as you lower the assembly and use your fingers to adjust the drive gear in the base to align with the teeth of the drive shaft.

At this point I tested the mechanism to check for noises, and everything sounded great. There is enough surface lubrication from the assembly process to briefly perform this test without oil in the base, but I wouldn't recommend running the assembly without oil pumping for very long.



Once the base is filled with oil and the spin cage and base are coated, perform a test to make sure oil is running through the mechanism up to the top oiling holes in the spin cage. The pressure of the revised pump is drastically higher than the original finger style. I had oil flying across the room within seconds after filling the base with oil, whereas in the past I've seen the finger style pumps take several seconds and the pressure is enough to push oil just over the bearing.

Pro Tip: Oil. The service manual calls for 25 oz of oil, which is just a hair above 1.5 pints. GM provided an oil for reopperating Unimatic and Multimaic mechanisms without specifying the specifics of the oil (type or viscosity). Robert has used Air Compressor Oil in the past and I've found this to be the best option for Uniatmics. Air Compressor oil is compatible with soft metals, it is a non detergent oil, and it runs sooth and quiet through the mechanism. I grabbed this bottle of Mobil when I ordered the spin bearing and o-rings from Grainger. I checked the bottle after filling to just below the gasket line of the mechanism base and it was spot on at 1.5 pints.[this post was last edited: 12/28/2019-20:56]

 

[swestoyz]

Last step in documenting the rebuild for today is getting the mechanism housing installed. Use the special bearing tool* to install the nut over a new bearing (SKF number 6006 JEM / Grainger 36MC24) and stake the threads so the nut is safely installed. Brushing and spacer should be installed with the groove facing up on the bushing and notch up on the spacer (third photo of four below, second photo shows the bushing upside down).

I cut and punched a new cork casket and used The Right Stuff to seal both sides of the gasket for the housing. I let it sit over night and came back and re-torqued the screws.

The reopperating manual calls for Permatex Number 2 on the threads of the mechanism nut, as well as on the gasket under the mechanism support. I bought a tube of this stuff years ago when I worked on a WO-65, so I'm not sure if you can still get it. Permatex No 2 is a tacky adhesive that I recall being used on other GM automotive items.

I also used RTV on both sides of mechanism support nut washer to make sure oil wasn't getting out of the mechanism. This mechanism came with the later 7535394 anodized washer, vs the original version (5433471) made from a softer metal.

I'll start working on Part 2 tomorrow - bench testing the mechanism and getting the cabinet ready for installation!

[this post was last edited: 12/28/2019-23:20]

 

[repairguy]

Wow! What an amazing documentation for folks in the future to tackle this rebuild. Thanks for the tips and amazing step by step instructions for the rebuild. Congratulations on breathing new life into another great piece of history.

 

[goatfarmer]

Another fine job, Ben, looks better than new!

 

[twintubdexter]

<span style="font-size: 14pt; color: #008000;">Of the many Unimatics I rebuilt, I never took one apart like that. Of course, way back then, they weren't all that old. I didn't realize there were so many individual parts. It does bring back a lot of memories. The 1958 models were the nicest of all the Unimatics. </span>