Differential cleanup and reseal

S

SteveInMissouri

Junior Member
I am getting started on a 56 Mercury Montclair restore. I found the differential nasty and obviously leaking at the seal. After pulling the plug a little black oil ran out a few spoons full. Next I removed the cover to find thick black goo. The shop is unheated and about 30 degrees, but this stuff is past cold and thick.

I know I need to clean this blob of goo out of there, but do I need to use something like a Carb Cleaner on the gearing before I seal it all back up and refill it?

Thanks,
 

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Barring disassembly and hot tanking carb cleaner is prolly your next best bet. It will take at least one can to do the job. Be sure to rotate the innards to get as much goo as you can. The seal is available, the cover gasket may be hard to find since it's a Dana 45, not a 44. A 44 gasket almost fits but not quite so unless you can find one you'll need to resort to silicone sealer.
 
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Put the rear cover back on and clean the outer housing/tubes first. You don't want any of that to hit the inside.
 
Likely bad bearings if it's been that way too long. You can clean it out with any petroleum based solvent. There is nothing in there that solvent or kerosene will hurt. You will just have to make sure you put some fresh lube in there before you run it much. Check it for shake on all the bearings. A person can use light grade motor oil as a flush. Modern SAE 10W/30 or thinner will work for an around the block run to flush more crap out. Good grade SAE85/90 for winter use from there on. Some parts are available for those axles. If it is a 45 then some things are interchangeable with the 44 but not all. You can buy gasket material at some parts stores & tap around the edges to get the fit. I'd change it to a Dana 44 or a 9-inch if parts were a problem. I always thought the Lincolns used the Dana 45 & Mercs the 44 but I have no experience with the 56 Merc.

PS: I forgot that Lincolns used the Dana 53 but they are likely about as hard to find parts for. There may be some similarity between the Dana 45 & 53. The Dana 45 was also used in GM trucks of the late 50s but they are 6-bolt axles.
 
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If it's the original axle it's a Dana 45. They look similar to a 44. 45-specific parts are unobtainium. Some 44 parts can be substituted with some creative shimming.

From Wikipedia so take it FWIW:

The Dana 45 was introduced during the 1950s as an upgraded Dana 44 with larger 20 spline axle shafts. Since the Dana 45 is no longer being made you can use the Dana 44 gears in the Dana 45 housing if you use model 53 pinion bearings and plenty of shims.
 
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It would have been easier to clean out if that had been a Ford Banjo housing rear end, since the pumpkin with the gears and all are removed with the carrier housing, but you have an integral housing rear end like the Ford station wagons had (those have a stamped metal cover on the backside).
I would put the drain and filler plugs back in and fill the thing up with parts cleaner solution and drive it around the block a couple times. Drain it and fill with 5W-20 motor oil and drive around the block a couple more times. Drain it a third time and fill with 90W gear oil. For the rear cap gasket, you can make your own out of a roll of cork material available at most chain auto parts stores. I have seen people do without a gasket altogether by just squeezing out Permatex Form-a-gasket from the tube they sell it in. Put your cap on with all the nuts in place just deep enough to squeeze out a little Permatex. Wait a couple hours and tighten all the nuts down. If it's done right, it will seal up as good as a gasket.
 
I agree that keeping any grit out of there is a priority. As far as a seal I was able to pick one up online at RockAuto. My plan is to put a thin film of Permatex on the cover and align the gasket on that then let it setup. Next put a bead of it on the pumpkin and let it get 3/4 set and mount the cover.

Right now the car has the engine and ****** out at the rebuilders. So the around the block flush out will need to be postponed, but if I understand there is no problem putting the back wheels in the air and spraying out the gearing and rotating the wheels until the goo is gone.

Then when I am back on the road again doing some flush out work. The car has been stored for nearly twenty years. I don't feel or hear anything I would relate to a bearing issue, but is there a good way to check while I am in the middle of this rear end project?
 
Thank you everyone for the advice, I got it cleaned out last night. Wow what a mess I thought the carb cleaner would thin it down to the point of being runny, and the goo would drain out. I was wrong, it did free it up off of the parts and get it in the bottom of the housing. Then I could scoop and drag the stinking black crap out of there. A couple of final clean outs with carb cleaner and everything I could see looked good.

When I am up and running I will do a couple flush outs with fresh oil.

Thanks again!!
 
Are you planing on replacing the pinion and axle seals at the least?


When put back into service, jack the car up with the differential off the ground (on stands) and let it turn with fresh lubricant. Drain, refill and run again listening for any bearing noise(es).


Make sure the vent is clean and functional.
 
Well KULTULZ, I'm probably a bit on the clueless side of this so I appreciate the advice. I assume the pinion and axle seals have set and dried out and need replaced.

I don't have any experience with replacing either of them, so I will need to get googled up on how to go about it. I know it has been pointed out that the Dana 45 is hard to find parts for. The cover gasket that i bought was way wrong and I went the gasket material route that was suggested by Daves55Sedan.

Do you have any advice on where I may be able to pick up new pinion and axle seals for this old guy?

Thanks,
 
Well, not having the correct FORD Catalog makes it a little harder. The seals (and bearings-cups) will (should) have ID NOS on them. There are specialty parts houses that deal mainly in bearings and seals. That is where you will find correct fresh replacement parts.
 
Mac's auto parts sells that rear cover gasket part # 1M-4035 for $5.99. It is listed as fitting 1951 - 56 Mercury and Ford station wagons and sedan delivery wagons. If you accidentally bought the gasket for the Ford banjo housing rear-end, that would be wrong since your "integral housing" type is a whole different animal.
They also show rear axle grease seals (they go behind the rear wheel bearings) listed for '49 - 59 FORD station wagon & sedan delivery (1-1/2" I.D. and 2-1/2" O.D.). Not sure if these are same as merc, but you could measure your old ones.
They show rear wheel bearings for Ford wagon '49 - 59 but I don't know if mercury had bigger bore in their housing.
Mercury pinion seal '49 - 56, (1-9/16" I.D. X 3-11/64" O.D.) part #8M-4676 for $12.49
Pinion bearing and race for '56 Mercury are sold separately; Bearing #8L-4630 and Race # 8L-4628
 
The 55 and 56 Tbirds used the Dana rear axle and the gasket for the back cover, pinion seal, rear seal and bearings are all available from the TBird parts suppliers, CASCO in particular, one company I have dealt with extensively and they are great to deal with.

Supposedly, the wagons and TBirds for 55 and 56 used the same rear end. And I heartily agree with the other poster who said put the rear cover back on (use a gasket), clean off all the crap around the cover (actually I would do the whole rear end) before starting to clean the inside of the rear.
 
In 1955 & 56, the Ford cars still used the precursor to the 9-inch and have a removable center section. The pickups, station wagons, police cars and Thunderbirds used the Dana 44. They are not a problem to source parts for. The Dana 45 & 53 are a different story. I'm not sure why FoMoCo went the Dana 45 route for the 55 & 56 Mercury but they did. They are hell for stout as are the Lincoln Dana 53 but if they go south, finding parts is a PITA.
 
It's almost as if Ford was anticipating a bigger engine for the '55/'56 Mercs, the MELs and FEs were in the works at that time. A Dana 45 and T-85 trans is much more driveline than even a very stout 312 could use up in a lifetime of squalling the tires while pulling out of the Dairy Queen...
 
I bet your differential is just fine. It did not completely run out of gear oil. Usually if its bad you will know it, teeth will be laying in the bottom of the case or a lot of silver colored paste will be in the bottom of the case. Differential bearing can last for hundreds of thousands miles if they have been over loaded with too much weight. If they do go bad its almost always the pinion bearings because they rotate three or four times more than the side bearings because of the gear ratio. Even then they will whine and make noises for a long-long-time, for years. It only takes aa few pits in a pinion bearing race to make them loudly sing going down the road.

At work our fleets trucks would break axles and blowup rearends all the time. Phone Company Gorillas driving them. We would stick a long magnet down the axle housings to get the metal chunks out. Then roll the solvent tank under the axle ends and spray the rest of junk in the housings towards the center section. Then we moved the solvent tank under the center section and hosed it out. Then we sprayed brake clean in there to get the solvent out. You always put new axle seals in if you have the axles out.

Once you have worked on hoists you will never lay on the ground again! I would quit working on cars if I had to do that. When I retired the first thing I did was install a hoist. Then I bought a used commercial grade solvent tank for $100.00. They outlawed them in businesses here in CA. You can only have water based solvent which does not work. The business I got it from had to get it off of their property or they would get fined, so I bought it. It needed a little work but I got it dialed in. You can see how much pressure that pump puts out without the hose on it. It cost me more to fill it with solvent than the tank cost. And now I don't want to use it because I don't want my pretty clear solvent getting dirty.
 

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SteveInMissouri said:
Well KULTULZ, I'm probably a bit on the clueless side of this so I appreciate the advice. I assume the pinion and axle seals have set and dried out and need replaced.

Messing around with replacing the pinion seal can change the preload on the pinion bearing if you do not get that nut back in the exact same spot. And I mean within an 1/16" of where it was at.

If the axle seals are out on the ends of the tubes like normal rearends then they will be easy to replace. I suggest if the pinion seal was not leaking that you don't mess with it and just put in new axle seals. Usually its an axle seal that leaks, at least it was on the stuff I worked on.
Click to expand...
 
I have found through the years that shop guys will "peen" the pinion shaft right at the edge of the pre-load nut, that way there is a noticeable mark they can see when putting it back together. Another outfit, I noticed, the guy got out a Dremel tool with a little cutting disk on it. Before doing anything, he took the Dremel and cut a little slot into the end of the pinion shaft and partially into the end of the nut. When re-assembling, he just screwed the nut back in and stopped when the slot on the nut mated up with the end of the mark on the shaft.
Problem I see with doing this is getting the proper type of seal puller. I made my own three-prong combo slide-hammer/seal puller to do mine. I could see any offered at the chain auto parts stores that would work. Otherwise, the job is pretty easy, as long as you have a bunch of large diameter pieces of junk pipe laying around you can use as a ram to hammer the new seal in with.
 
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