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1937 Diff Suggestions Needed


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I've never done anything with a differential and I'm looking for some suggestions on two things I want to do.

 

1. What is the simplest way to change the oil in the differential.  There's no drain plug just a fill plug so for those who have already done it, what's the best way to suck the heavy oil from the differential while it's still on the car?

 

2. Is there something I should know before removing the rear universal joint mount/base?  I know I'll have to lock the rear wheels from spinning in order to turn the nut.  You can see in the pix the old seal is leaking and needs replacing.  Is this a simple job to do?  I'll mark whatever I remove to put it back the way it was but beyond that, I'd appreciate any suggestions?

 

 

 

019.JPG

Edited by kookie1 (see edit history)
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You need to mark the nut and pinion shaft so that when you put it back you do not get it too tight and change the preload on the bearing.  I have a NOS, genuine GM pinion seal @ $40 & $8.45 postage.  Kurt Kelsey 641-648-9086  Thanks!

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26 minutes ago, kookie1 said:

1. What is the simplest way to change the oil in the differential.  There's no drain plug just a fill plug so for those who have already done it, what's the best way to suck the heavy oil from the differential while it's still on the car?

 

You could use a suction gun, but that might sour you on the hobby forever. Maybe you can remove the bottom bolt of the pan and let it (really slowly) drain out the bolt hole. Works on 1936, not sure about 1937 (different rearend).

 

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On 6/3/2021 at 11:23 AM, kookie1 said:

I've never done anything with a differential and I'm looking for some suggestions on two things I want to do.

 

1. What is the simplest way to change the oil in the differential.  There's no drain plug just a fill plug so for those who have already done it, what's the best way to suck the heavy oil from the differential while it's still on the car?

 

2. Is there something I should know before removing the rear universal joint mount/base?  I know I'll have to lock the rear wheels from spinning in order to turn the nut.  You can see in the pix the old seal is leaking and needs replacing.  Is this a simple job to do?  I'll mark whatever I remove to put it back the way it was but beyond that, I'd appreciate any suggestions?

 

 

 

019.JPG

if you remove 2 or 3 very bottom bolts from the carrier, the old fluid will drain, pontiac used the same basic designed of the carrier from 1937 to 1956

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  • 2 weeks later...

So I have used a 12V oil suction pump that has a small diameter suction line that will easily enter the housing fill plug. I've used these to empty crankcases in boats and transmissions that the drain plug when opened will only create a huge mess to clean up. These pumps are  cheap and available on Ebay  and will pull the heavy weight oil out in short order.

Also - If you are changing the pinion seal then jack the vehicle up at the rear and support under the rear axle then remove the rear uni joint base as you call it and the pinon seal, , a lot of the oil will then drain through the pinion shaft bearings  and you wont have to pump much out if utilising the vacuum pump method. Thats how i changed my final drive oils in my old Chieftains......

 

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Draining from the bottom bolt on the differential WAS the way to go if you can.  I had some hand pumps to use but was wondering how to get the tubing to go to the very bottom from that rear fill hole.  Thankfully I didn't have to do it that way.  I'm not sure with a '37 differential you get absolutely ALL the oil out with the lowest bolt but you must be pretty dang close.  I plan on flushing it anyway with some mineral oil so the little oil left is not really an issue.  Thanks guys for the help!   

Since I usually ask others for pix I better produce a few of my own.  After looking at the differential in the past (first pix) it was obvious it needed an pinion seal so I had purchased one long ago.  The U-joints needed re-greasing (at 30,000 mi. according to the shop manual) since the car already had 35,000+ miles on it so it was time to do both jobs.  I decided to replace the u-joints with ones that had a grease nipple as well.  I mostly sand blast everything, within reason, which is why it lookes in the picture rather light colored but it's just to remove all the surface rust.  I applied POR 15 to the drive shaft before putting the u-joints back in.  Anyway, thanks for all the suggestions.   You guys are a great resource!

000 - Before Starting.jpg

001 - New Diff Seal Installed.jpg

002.jpg

003.jpg

004.jpg

005 - Propellor Shaft End.jpg

006 - Differential End.jpg

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Nice job !

Straight 8 - the rear uni joint with the grease nipple that will fit is  Hardy Spicer 114-2111  - it has  the  correct  flat flanged  cups  for mounting on the  Pontiac pinion flange.

Hope that helps. 

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Dave - So the front u-joint is different on my '51  as it has 4 round cups that are more typical of later model U-joints as compared to the flat face mounted cup type in the rear. 

Looking at Ebay here it seems that both front and rear for a '37 are the same. 

I had to go with Hardy Spicer here as that was the only supplier available locally that could supply that style of flat faced cup joint.  To import from your part of the world is worth more than the component is nowadays...

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Yes, Dave, the front and rear u-joints are identical.   I bought these two NOS Haberle #2000X (US made) at different times several years ago off Ebay knowing I would eventually have to change them.  I had to remove all the needle bearings in each one to clean out all the old, hard grease and replace with fresh grease.


You've also got good advice from Russ about the Hardy Spicer 114-2111 universals.  I wasn't aware of them at the time I was interested.   Those flat faced cups are not easy to find.

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The Internal seals on the Hardy Spicer u joint cups  are the modern elastomer type . I have fitted them to both my 51 and the 53 that my  Dad had and so far its all good. Not that they do a lot of miles nowadays but every time i put the grease gun to it they dont take a lot of grease to refill the cup, and there is no evidence of grease fling out around the transmission tunnel or diff  floor pan area.  So far so good, they should outlast this current owner  :)

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