Differential case repair questions.

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nsbrassnut
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Differential case repair questions.

Post by nsbrassnut » Wed Dec 07, 2022 9:09 pm

Hi All

I'm sorting rear end parts to use in m '13 T project. The car is a dismantled basket case and some parts are pretty rough.

The question today is to look for suggestions for differential case repair suggestions. The spider carrier in the original case has wear and can be "jiggled" a bit in the case. And both side holes where the axle gear rides are worn .005 to .010" over size.

I went into my parts pile and out of a total of 8 different differential cases, only one, and maybe two will hold the spider tight. And every single one has the axle gear hole on the crown gear side worn over size by several thousands inch. And also, each one on the crown gear side has worn "shoulders" where the steel and bronze thrust washers ride. So I don't trust that side to keep the bronze thrust washer in line and there could be a risk of it dropping down and jamming.

The rear axle rebuild guide mentions "replace or repair" when the wear is more than recommended. So far replace doesn't look like an option here, so I'm down to repair.

I tried a search of the forum for old postings on the topic but didn't have much success.

So can anyone provide some suggestions and experience on ways to repair/rebuilt the differential cases to both hold the spider tight and resize the axle gear holes and shoulder. Such as machine a new axle gear sleeve and install it in the differential case sections.

Thanks

Jeff
Nova Scotia


Kerry
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Re: Differential case repair questions.

Post by Kerry » Thu Dec 08, 2022 2:57 pm

Up to about 1914 the cases had brass bushings for the spider and axles, either find an early one to re-bush or machine one to take bushes or if only several thou, just leave it.


Kevin Pharis
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Re: Differential case repair questions.

Post by Kevin Pharis » Thu Dec 08, 2022 4:42 pm

The early housings had a bushing of adequate wall thickness. Later housings may lack adequate material thickness to accept a bushing without sacrificing strength. I have repaired several Ruxtell carrier housings by boring out slightly (approximately .040”, brazing up the bore, and re-machining to proper clearances. Beware tho, I have had a couple parts shrink due to the heat, and became unusable…


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Re: Differential case repair questions.

Post by speedytinc » Thu Dec 08, 2022 5:28 pm

This is a job for a good lathe operator.
The carrier can be bushed on both sides to get back to spec to carry the axles. (1.812 ID. to fit a stock gear, 1.807 OD) .005" stock clearance.
I normally use a 2.00" OD bushing. If the thrust washer retaining collar is too bad, use a thicker walled bushing to match. Machining a step in the bushing where it goes thru the carrier. Locktite/press in place. Carrier material is plenty thick to rebush.
As far as the spider fit goes, a little belt sanding/slight cut on the faces will narrow the holes to grip the Y. This area isnt usually worn that bad.
If to worn, you could build up the 3 spider legs into a custom oversize to match the carrier's wear. I have not seen a carrier that was that worn.

I use this method to save worn rux parts. The bell & the castle, where the axles ride.


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nsbrassnut
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Re: Differential case repair questions.

Post by nsbrassnut » Thu Dec 08, 2022 6:44 pm

Hi John

Careful machining and installing a new steel bushing to restore the fit where the axle gear goes is what I was thinking also. Just wanted to hear how others may have done it.

Some of the spider "fingers" that sit in the casing on a couple of them appear to be very rough machined from the factory where the end of the finger is held between the halves of the case and actually measure undersize from the numbers mentioned in the repair book. Those ones surprised me. And those spiders are a bit loose in most too from age.

I was also thinking about carefully sanding one side of the casing to tighten up the fit of the spider hole as you noted. Inspection with a flashlight showed that only one face of the two in the step actually contact and shaving a few thous by careful sanding on a flat surface may be enough to tighten them up.

And yes, what I'm calling the case is what I think you are calling the bell and castle. I haven't heard it called that before. :^)

And for the centre of the spider, I have both the early bronze bushed ones and the later all steel ones. So I have options there also.

And I do have a lathe and beginner's level experience so it is something that I may be able to do. At least I have spare parts to practice on first to decide if I can do the job well enough. If not, I think I know someone others who can help out.

Thanks for the advice.

Jeff


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Re: Differential case repair questions.

Post by speedytinc » Thu Dec 08, 2022 7:05 pm

The castle is the carrier equivalent component in a ruckstell that holds the spider.

The carrier right side half has a step to it that mates to the left side with the opposite steps. So at least 2 surfaces on one half need to be reduced to tighten the fit.

Indicate the carrier to the ring gear mounting faces. Extreme precision is called for.


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nsbrassnut
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Re: Differential case repair questions.

Post by nsbrassnut » Fri Dec 16, 2022 6:20 pm

Hi John

I tried the carrier in my lathe and I can get it set up on the four jaw chuck and turn the axle hole for bushing sleeve. And with patience and a dial indicator I can get is dialed in in both dimensions to get it straight and true within 0.001 inch which should work for a T.

Can you provide some suggestions on the sleeve to carrier fit and loctite product to use for the repair.

After some more cleaning and slight mix and match of parts I came up with an assembly that holds the spider carrier properly. But still needs one side sleeved to both close up excessive wear in the hold and repair the worn/damaged step that holds the bronze washer in place.

Thanks

Jeff


speedytinc
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Re: Differential case repair questions.

Post by speedytinc » Fri Dec 16, 2022 6:29 pm

A tight press fit about .003" I normally use a locktite bearing/bushing setting liquid. Its blue. Since this is a permanent fix, red would be fine.
Make sure the 2 holes in the diff are perfectly aligned. The ring gear must center to the axle holes. I would mount one half indicated in the lathe, bolt the other half on & do the final bore


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Re: Differential case repair questions.

Post by RGould1910 » Fri Dec 16, 2022 6:41 pm

You probably know this already but although you want precision in the dimensions of the parts, you don't need or want close tolerances in your fits. Biggest reason is the axle housings are never precisely aligned and you need enough tolerances to prevent binding. I'm talking about the holes in the differential case where the axle gears ride. The spider should be tight in place. If I were you, I would shoot for no closer than .005" clearances. You'll have to machine each sleeve differently because the dimensions of axle gears will be different.
I assume you will be using bronze bushings. May I recommend phosphor bronze. If appears to my eye that the bushings Ford used on the earliest cases were phosphor bronze. I would try an interference fit of 3 thou and see how that works. If you go with Loctite and opt for a slip fit, I'd go with Loctite Sleeve Retainer.
On the Perfecto 2 speed rear ends I've rebuilt, I ve used Sleeve Retainer with phosphor bronze bushins in the bell housings.


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Re: Differential case repair questions.

Post by Original Smith » Sat Dec 17, 2022 12:19 pm

You don't need to bother with the 1913 case. Just use a later one. They are everywhere.


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Re: Differential case repair questions.

Post by speedytinc » Sat Dec 17, 2022 12:55 pm

Didnt the 13 & earlier carrier run a smaller axle gear race? In this case bore to later axle gears & replace the geras with later. Also, werent the spider gears brass bushed?

Regarding gear clearance. Originally the gears measured 1.807" & the carrier hole 1.812". If you have worn gears, you can compensate in the carrier bore & maintain .005" clearance. However, standard or very low wear axle gears are more common. I gotta have 20 or so that I salvaged from the more common bad axle shafts.


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nsbrassnut
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Re: Differential case repair questions.

Post by nsbrassnut » Sun Dec 18, 2022 5:48 pm

Hi All

I'm unsure about the bronze bushed earlier differential cases. In my '13, its a late year Canadian model and the differential that came with it is all cast iron, but the spider holder does have the bronze bushing. The car was apart when I got it and is a bit mixed up. It has some '14 style parts, but whether they all came with it originally or they were early repair/replacement parts I don't know.

A bit of an update on my project. I dug 8 differential cases out of my spares pile. That actually represents a significant portion of the local population of T spares in my neighbourhood too. Out of the bits I was able to assemble 4 differential cases that hold differential spiders still as they should. The others had varying levels of serious wear, in some cases enough to make the spider arm holes in the differential case oval and tapers. And one of the spiders with the fingers also worn oval where they mount in the case.

And in most the non-crown side of the case the axle gear hole and thrust washer lip is good with only 4-5 thou wear in the hold. Enough to still use with a good axle gear based on the guidelines in the axle repair book. However every single one has either or both serious wear in the axle gear hole, up to 30 thous oversize and wear damage on the lip that the thrust washer ride on. Enough that there is a serious risk of a thrust washer jamming the differential.

So my new plan is to use one of the cases and spider holder that fits tight. And then machine a steel step bushing to press into the crown gear side of the carrier to restore the axle gear hole bore and thrust washer shoulder.

I did take some pictures of the worn parts and will try to post them later.

Stay well.
Jeff


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nsbrassnut
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Re: Differential case repair questions.

Post by nsbrassnut » Sun Dec 18, 2022 6:04 pm

Here are some pictures to try to show a bit of what I'm working with.

The picture which has both sides of the differential case has a non-matching "top" on it from another one. But hopefully you can see how much the bottom half (crown gear half) has had the spider pin hole worn oval.

The other pictures are examples of the wear damage to the thrust washer collars and how much wear there is in the axle gear hole with a gear placed inside the hole.

A friend had some mechanical tubing of about the right dimensions that I can make the stepped bushing out of. Made one so far for practice and to test my fabrication proceedure. Now to make a second better one based on some learnings along the way.
Attachments
Diff Case 4 - Copy.jpg
Diff Case 3 - Copy.jpg
Diff Case 2 - Copy.jpg
Diff case 1 - Copy.jpg


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Re: Differential case repair questions.

Post by RGould1910 » Sun Dec 18, 2022 9:09 pm

Interesting. How are you planning to fix the stepped bushing to the crown side carrier? If I were doing the work, I would take steps to insure that the bushing would hold fast and not break free and either revolve or migrate outward against the roller bearing
Just a thought. If youre going with an interference fit, using a steel bushing, keep the tolerances very small to avoil breaking the carrier. IMHO, you'd do better making your bushing out of either 660 bearing bronze or phosphor bronze. Either will crush down easier when fitting without risking damage to the carrier.

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