Jump to content

Replacing rear end pinion seal on 1950 Dodge Meadowbrook


frcc16

Recommended Posts

In a few months, I will be at a point where I'll have to replace a leaking pinion seal on the rear differential of my 1950 Dodge. Examining it, here's the steps I see...

1) Drain oil

2) Remove bolts connecting rear yoke (or flange?) to drive shaft and move shaft out of the way

3) Remove cotter key from castle nut (or flange nut) and remove castle nut from the pinion shaft

4) Remove yoke

5) Remove the case bolts and work the case cover free and replace seal and gasket...

However, I have learned that the castle nut (step 3) also serves to pre-load the pinion bearings.

I don't have the tools to properly torque the castle bolt back into place when I reassemble everything.

Am I crazy to think that I can keep track of the exact position of the castle nut before I remove it, then be very careful to tighten it back into exactly the same position???? Can I hope that the pre-load will be preserved by following such steps? Anyone done this already?

Link to post
Share on other sites

It is possible to do that if you are careful. It has been done that way many times, if you do not change the preload everything will be ok.

If there is no gear whine and no excess play in the gears, that is the best way to do it.

Retorquing only works if you replace the crush spacer and there are other details to getting it right.

Link to post
Share on other sites

I may be reading this wrong but if you only need to replace the pinion seal you don't need to drain the oil or mess with the carrier gasket. Remove the drive shaft at the differential, remove the pinion nut, remove the yoke, remove the seal, install a new seal and everything else again. I believe those old Chrysler differentials use a spacer and shims to preload the pinion bearings, Not a crush sleeve. If this is correct, it would be hard to overtighten the pinion nut.

Link to post
Share on other sites

OK.. maybe I'm asking the wrong question!! I would have thought that the pinion seal is inserted from the inside of the case and is held in by a lip on the case. Can it be installed from the outside?

Link to post
Share on other sites
OK.. maybe I'm asking the wrong question!! I would have thought that the pinion seal is inserted from the inside of the case and is held in by a lip on the case. Can it be installed from the outside?

Just double checked the '46 to '54 Plymouth factory service manual (pretty darned sure Dodge is the same as Plymouth in this regard) to verify that the basic design concept is the same as for my much older car. You should pick up a service manual for your car!

The seal can be removed and re-installed "from the outside". Bearing preload is set by shims. The pinion flange nut is torqued to 175 ft-lbs when you put it back together.

Not in the manual but you should check the surface on the flange that the seal works against. If it is damaged at all, get a speedi-sleeve installed to give you a smooth surface for the seal to seal against.

Link to post
Share on other sites

If you cannot pry the seal out try drilling a small hole in it, then put a screw in that hole and pull it like a nail.

Link to post
Share on other sites

Hey frcc16, This job can be accomplished in just a few minutes if you have a lift ro raise your car on. Even outside under a shade tree it is not a very hard job. Getting the old seal out is sometimes hard. Just drill a hole in it and run a self tapping screw in and either pry the seal out or using visegrips on the screw and a hammer on the visegrips. Seals with a lip can be removed with a screwdriver and a hammer.

Link to post
Share on other sites

The factory seal can be tough to pull out with out the right tools.

The screw trick will work-maybe. You might end up totally destroying the OE MoPar seal to get it out. Do what ya gotta do to remove it. Just don't nick the case or pinion flange. You will need to hold the pinion flange firmly to be able to remove the cotter pin and 1-1/4" nut.

An 1/2" impact gun will quickly remove this nut but....... could damage a gear- I say could!

Aftermarket replacement seals are very wimpy in construction compared to the OE seal and can be easily removed as they have hardly any thick steel in them.

A scew type factory seal removal tool used to remove the same type seal on the rear of a 1950 Chrysler M6 Trans shown....

Bob

post-62228-143142625088_thumb.jpg

Link to post
Share on other sites

As having replaced many diff pinion seals in my time as an Auto mechanic, I would offer the following as a suggestion to prevent any issues with pinion bearing preload on re-assembly.

Mark the position of the nut, the pinion shaft and yoke before you undo it all and start removing things. A gentle centre punch mark across all 3 elements on a straight line will do the job well. Take a picture of it all with the witness marks before you dis-assemble it all....

Use a long holding tool on the pinion flange ( a pipe wrench works well as it has a long handle that you can wedge against the floor ) to hold the pinion static and not load the diff gears when undoing the pinion nut...... the nuts can be extremely tight on older vehicles and bigger diffs.....

Sometimes you may not be able to get an impact socket on to the nut so have to use a normal thin wall CRV socket to suit and a large breaker bar....

If you jack the front of the vehicle up, then all the oil should stay in the final drive diff housing when you pop the seal out.

Generally a pry bar will pop the seal out of the housing, but be carefull to not damage the counter bore in the housing otherwise it may leak oil from the O.D of the seal if you create a leak path.....Also the seals can fly out and cause damage to the seal removal tool operator so pls be carefull you don't wear it , as I did one time......

When you re-assemble - lube the seal lips and check the pinion for seal tracking, if there is a groove worn then a Speedi Sleeve is a good repair option.....

Install the seal using a suitable installing tool like a large 3/4 drive socket or seal drivers....

Align all the punch marks back up and then re-assemble it all in exactly the same orientation as it came out....

Re-tighten the pinion nut to align the witness marks and you should be good to go.

Best of luck :)

Oh - Don't forget to check , refill the oil level if the seal has been leaking ...

Link to post
Share on other sites

Thanks for the help with this..... I just spotted a disturbing thread on this posted back in 2005. The jest of it was that you really need a hefty impact wrench to loosen the flange nut. OK, well I don't even have an air compressor! It was encouraging to hear that these nuts can be loosened with a breaker bar!

Link to post
Share on other sites

Yes , most definitely can break out the nut with a breaker bar, the trick is getting enough purchase on the bar ( especially if you are working above ground level) I used a 24inch bar on most occassions, and holding the pinion still to break out the nut..

Its quite simple if you have a hoist as you can gain some mechanical advantage on the breaker bar....

Most pinion nuts on cars are tightened anywhere from 100 to 150 ft.lbs initially to get the crush / bearing preload correct on the pinion.

Cheers

Link to post
Share on other sites
  • 1 year later...

Well,  up to yesterday, I had resigned to leaving removing the castle nut to a mechanic with the right tools.... BUT, yesterday, I decided to at least have a look at it an see if I had a shot at loosening it myself....  I removed the drive shaft, pulled out the cotter pin and......

 

WAS ABLE TO REMOVE THE CASTLE NUT WITH MY FRICKEN FINGERS!!!!  It wasn't even tight!!!!  Yikes!

Link to post
Share on other sites

In hopes that when torqueing it back up it still rotates freely.

Probably will but I always prepare for the worst and hope for the best.

 

I have a 52 Plymouth parts car here if you end up needing a rear end.

Link to post
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...