Rear axle ratio Ford 1947 QUESTION!

[Harylufa]

Hi all!
I have the chance to buy an used Differential that is complete. It is a 1947 differential but my car is 1946.
The question is: Is there something different? I´d like to buy it as spare part.
But before that I want to be sure if it is correct one for my car.
I attach a picture of it. It is on sale as it is.

Thank for your advises.

Harylufa

[Gary in La.]

The rear axel assy's for 1942-48 are the same with the exception of possibly a different gear ratio. There should be a number stamped on the bottom rib of the banjo that you can compare to your rear axel. Keep in mind the ring and pinion could have been changed at sometime prior and is now different than what it came with. If the price is right it would be a good investment no matter what the ratio is.

[ford38v8]

What he said.

[Old Henry]

Funny you should ask this question. Just a couple of hours ago I stumbled onto this discussion by "Uncle" Tom McCahill* about the difference in gear ratios in the differentials of the '46 and '47 Fords. Very interesting read and very enlightening: http://auto.howstuffworks.com/1941-1...er-deluxe8.htm

Wish I had that '47 rear axle right now. Looks like I'm probably going to need it or at least parts from it. (http://www.fordbarn.com/forum/showthread.php?t=89703)

*Uncle Tom McCahill conducted the first published road test in America which appeared in the February 1946 issue of Mechanix Illustrated. The first car he road tested was a 1946 Ford DeLuxe sedan - just like yours Harylufa (except yours is a coupe). (More about "Uncle" Tom here: http://www.joesherlock.com/Tom-McCahill.html)

[ford38v8]

Henry, save that link to McCahills review of the gear change. Whenever someone asks about ratios on the Barn, post that link. McCahill was a very well respected expert on cars, as can be attested to by the review. I used to love reading of his road tests, as did most kids I knew back then. Tom was very influential back in the day!

[Harylufa]

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Hi all!
I was trying to find out "There should be a number stamped on the bottom rib of the banjo that you can compare to your rear axle" told by Gary in LA but it is impossible see it.
What do you think If I buy this differential? the price U$s 120.-COMPLETE as you see in picture including rear spring assembly too.

I think it is a real opportunity.

Please help me to decide

Harylufa

[Mart]

Just buy it, for that price it's worth it just for spares.

I put a little video on youtube showing how you can check the axle ratio.

http://youtu.be/bkvp3Fq21ZM

Mart.

[Harylufa]

Originally Posted by Mart

Just buy it, for that price it's worth it just for spares.

I put a little video on youtube showing how you can check the axle ratio.

http://youtu.be/bkvp3Fq21ZM

Mart.

Hi Mart!

I have just seen the video It is very interesting, thank you for showing us how to check it.

Please if you have something more that i must know please let me know.

Harylufa

[Harylufa]

Hi All!
Finally I bought the diferential. I attach some pics.
Please I´d like you take a look at this and please!!! give all your opinions.
I want to take this as a PROJECT and rebuild it if I can. All information you have tutorial pics etc etc, will be welcome.
I hope did a good purchase...
Keep in touch

Thans all

Hary

[Fibber Mcgee]

$120. Looks like you made out pretty well. You'd be lucky to get the spring for that over here.

[Harylufa]

Originally Posted by Fibber Mcgee

$120. Looks like you made out pretty well. You'd be lucky to get the spring for that over here.

Hi!
Yes, I must clean It. How can I know if spring are in good conditions?

Thank you.

Hary

[bobH]

Regarding the pictures... Turn it over, bottom side up. Clean off the web that is directly below the pinion bearing - should be some numbers stamped there, numbers like 39 11 or 34 9 or 37 9.
The brake assemblies, at least in my area, are worth most of what you paid.
As for condition - a look inside would be my next interest. Most of the rear ends that I have pulled apart, if they have been stored outdoors, have had water in them. And, there is usually nothing usable in them. You could pull the fill and drain plugs first, and see what you can see. Water or rust would be a bad sign. Looking through the plug holes with a flashlight (preferably at night) might give a clue as to what the inside looks like.
As for differences... 46 and 47 were years that some changes were happening, at least at US plants. Nothing that would make any difference to you, but sometime along in there, they introduced the brackets (bolt-on) that were to later be used for tube shocks - on some 47's, and 48's. So, it's possible that your 46 would likely not have some unused lower shock brackets. And, the 47 might have some lower shock brackets installed. No big deal, and it would make no difference.

[Fibber Mcgee]

Originally Posted by Harylufa

Hi!
Yes, I must clean It. How can I know if spring are in good conditions?

Thank you.

Hary

Check for broken leaves first. But as far as being worn out (needing to be re-arched) I'm not sure other than putting it in and seeing where it sits, maybe someone on here has a better way to tell.

[Harylufa]

Originally Posted by bobH

Regarding the pictures... Turn it over, bottom side up. Clean off the web that is directly below the pinion bearing - should be some numbers stamped there, numbers like 39 11 or 34 9 or 37 9.
The brake assemblies, at least in my area, are worth most of what you paid.
As for condition - a look inside would be my next interest. Most of the rear ends that I have pulled apart, if they have been stored outdoors, have had water in them. And, there is usually nothing usable in them. You could pull the fill and drain plugs first, and see what you can see. Water or rust would be a bad sign. Looking through the plug holes with a flashlight (preferably at night) might give a clue as to what the inside looks like.
As for differences... 46 and 47 were years that some changes were happening, at least at US plants. Nothing that would make any difference to you, but sometime along in there, they introduced the brackets (bolt-on) that were to later be used for tube shocks - on some 47's, and 48's. So, it's possible that your 46 would likely not have some unused lower shock brackets. And, the 47 might have some lower shock brackets installed. No big deal, and it would make no difference.

Hi BOBH!

I will investigate all you mentions and came back with news

Thanks

Hary

[Harylufa]

Originally Posted by Fibber Mcgee

Check for broken leaves first. But as far as being worn out (needing to be re-arched) I'm not sure other than putting it in and seeing where it sits, maybe someone on here has a better way to tell.

Fibber Mcgee!!

One thing that I have to do is change front springs and back springs. My car jump always and its very hard.

I must find out if this one work fine, in this case I ´d change it.

Keep in touch and thanks

Hary

[G.M.]

Make sure the bearing surfaces under the tape is in good shape. As long as it wasn't stored out side with the torque tube bell up and not covered it shouldn't have water in it. G.M.

[ford38v8]

Somebody mentioned the brakes... Those brake shoes are unobtainable here in the States, do your best to salvage them.

You have a 19 tooth speedometer gear, which indicates a 9/34 pinion/ring set, producing a 3.78 final ratio. This is a good all around ratio for your car, likely the same as you have now, but will be a spare.

[Fred A]

The 3.78 ratio is OK but if you ever need to use the gears, it would be better for many well funded owners to buy the 3.54s and give your engine and ears a break at road speeds. Next thing would be the axle bells. Ford discontinued the grease fitting at the cost of more worn housings. If worn, they would only be a convenience to sleeve the bearing race on the spare before taking the car out of service. Condition of the axles in case your originals are either stripped or spun on the taper is usefull. Brake parts can be useful if included. Springs may not be that thrilling unless yours are rusty. Super Deluxe had the desirable covered spring. Others, not so much. Inspection of what you have will give a better idea how useful a spare may be. Good Luck: Fred A

[Harylufa]

Hi all!
Here I found a number. What do you think? Now I must discover my number diferential.

Please keep in touch

Thanks

Harylufa

[Harylufa]

Originally Posted by ford38v8

Somebody mentioned the brakes... Those brake shoes are unobtainable here in the States, do your best to salvage them.

You have a 19 tooth speedometer gear, which indicates a 9/34 pinion/ring set, producing a 3.78 final ratio. This is a good all around ratio for your car, likely the same as you have now, but will be a spare.

Hi!
I think you are right;
"which indicates a 9/34 pinion/ring set, producing a 3.78 final ratio."

Now is this correct?

Harylufa

[G.M.]

The numbers stamped on the bottom of the bell housing won't tell you the ratio if the gears were changed unless someone restamped it. The easy way to check the ratio is put a vice grip on the drive shaft pointing up at 12 o'clock. Mark the tires or drum with chalk at the bottom. Roll the wheels forward one complete turn counting the turns of the vice grip. 4 turns = 4:11, 3 3/4 turns = 3:78 and 3 1/2 turns = 3:54. In the car mark the tires, mark the crankshaft pulley, put in HIGH gear and push the car to move the tire ONE turn watching the mark on the pulley. Same number of turns as the vice grips tell the ratio. G.M.

[Harylufa]

Originally Posted by G.M.

The numbers stamped on the bottom of the bell housing won't tell you the ratio if the gears were changed unless someone restamped it. The easy way to check the ratio is put a vice grip on the drive shaft pointing up at 12 o'clock. Mark the tires or drum with chalk at the bottom. Roll the wheels forward one complete turn counting the turns of the vice grip. 4 turns = 4:11, 3 3/4 turns = 3:78 and 3 1/2 turns = 3:54. In the car mark the tires, mark the crankshaft pulley, put in HIGH gear and push the car to move the tire ONE turn watching the mark on the pulley. Same number of turns as the vice grips tell the ratio. G.M.

Originally Posted by Mart

Just buy it, for that price it's worth it just for spares.

I put a little video on youtube showing how you can check the axle ratio.

http://youtu.be/bkvp3Fq21ZM

Mart.

Dear Friends!

Here I put a video testing axle ratio check "differential" teached by Mart and G.M from FordBarn.

https://www.youtube.com/watch?v=OfWXtT0o0Lw

As you can see the result is 3 3/4 turns so the ratio is 3:78.
Am I right with this check? please correct me.

Thank for your answers

Harylufa

[Harylufa]

Hi!
Please tell me if you could see the video.

Thanks

hary

[Mart]

That's great, Hary.

If the opposite hub did not turn, that is indeed a 3.78 ratio.

Thanks for the "Name check"!

Mart.

[Drbrown]

A little late to this conversation but thought I'd add that my 1947 Ford model 79A 5 passenger Sedan Coupe was built in June 1947 and has its stock 3.54 spiral bevel diff with factory shock brackets using tube shocks.

[hellmet]

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how about a 47 rear end with a #18 speedo drive does it have 354 gears?