Diff assembly coming soon
 

I got all my parts cleaned up and new parts arrived. The carriers were knurled and next step will be assembly. I also made trial bearings to aid in figuring out how many shims I will need. Once I figure that out I will install the new bearings. Wish me luck.

Re: Diff assembly coming soon
 

Trial Bearings? I am not following this. the amount of preload on the bearings will very, unless you have copied exactly, the bearings to be used, or am I missing something obvious?

Re: Diff assembly coming soon
 

Bearings (Timken) are made to VERY close tolerances. Timkens made today match VERY closely Timkens made in 1930.

Yes, they are that good.

I'm not sure what "Dummy circles" would do in this case? The preload is determined as "rolling friction" of the carrier held between the left and right trumpets and could not be duplicated except by method given by Tom Endy (or Rick Freeman back in the 1970s)

OR only slightly later in the process - finding the "wear spot" matching the pinion to the ring - which is normally adjusted AFTER you have the carrier "total gasket" determined to make the preload (or possibly shims if yours is as far out as was first described.)

Once preload gasketing thickness is established, one adjusts the gaskets from left to right (or substitute A for B,B with the total remain the same) to get the "contact spot" correct radially on the differential bevel gear tooth/pinion.

Or am I missing something here?

Perhaps you could outline what you expect to be the methodology and let us comment on it?

Joe K

Re: Diff assembly coming soon
 

Since I don't know how many shims I will need under the carrier bearings I can use my test or trial bearings to get close without having to press them on, pull them off etc multiple times. Since these pull of easily it makes life much easier plus less risk of damaging my new bearings.

Re: Diff assembly coming soon
 

Bearing preload (and its establishment) exists as a way to "compensate" for small differences between bearings. It also serves to "locate" parts, compensate for reduction in race size occurring during pressing in (interference fit) and allow components to be assembled to optimal situation.

Substituting another "filler" defeats the purpose of pre-loading - because you can never establish EXACTLY the same degree of compression, location of bearing, tolerances of parts in the filler pieces.

You may end up with a "loose" bearing (causing roller skid) or a tight bearing (causing brinnelling of the race, and a hot bearing, or failure.)

Bearing preload is "individual" to the components being loaded. It brings them together to a "one and only" conformance - specific to that assembly.

Check out a good description of the whys and wherefores of bearing pre-load at https://www.bearingtips.com/preload-...-applications/ He discusses ball bearings (angular contact) but the theory is the same for roller bearings.

Again, I would follow Tom Endy's instructions. If you're having problems establishing a preload (as you found it with NO gaskets) then something is not right in the assembly.

I'm thinking someone may have modified the carrier?

One solution which MIGHT bring you to a proper gasketed condition would be to put the shims BETWEEN the two halves of the carrier - and then you could use proper gaskets - but (thinking out-loud) this might cause a need for shims under the differential gears/axles to bring the bevel gears closer to the spider gears? I think we saw that as a possible cause (bevel gear seat?) which perhaps a previous rebuilder may have corrected by shaving the carrier halves?

Joe K

Re: Diff assembly coming soon
 

Re: Diff assembly coming soon
 

Complete rear end assemblies are large . Most wouldn't want to pay the shipping cost .

Re: Diff assembly coming soon
 

I just bought two differential carriers - one a Model A and one for the 32 up Ford. They're similar in appearance and probably fill the spot the same in a Model A housing. Also a banjo housing which I don't need. Also a rear axle shaft/gear - usable. All $20. For $5 he threw in a trumpet which has a good spring perch although the bearing seat is worn egg to 20 thousandths.

The stuff is out there. And pretty cheap really.

I could have bought a pressure plate on Ebay buy it now for $8.50. Advertised as flat but restorable. It looked pretty good. But shipping was $14.50.

I have paid more for shipping than the price of the part. But not that time.

Joe K

Re: Diff assembly coming soon
 

Just adding a follow up to complete this thread. I would caution anyone trying to use trial or setup bearings to get a guess on how many shims would be needed under the carrier bearings. I spent quite a bit of time determining this all by using setup bearings. When I went ahead and put in the final new bearings I ended up removing 4 shims, which was a real pain. Both old and new bearings were timken so you would have thoughts would get similar results and be close. Definitely assume the new bearings will use less shims to lockup the carrier.

Re: Diff assembly coming soon
 

Looking at your photo I think you will find that you will need two of the large wrenches that fit the two large nuts on the pinion sleeve when it comes time to set the pre-load there.

Another tip: When you have the hubs on the carrier knurled, have the machinist take a .005 cut on the bearing stop to true it up, then add a .005 shim there. Have another cut taken below the stop about a 1\4" deep and about 1\8" in. This will allow more room to get a bearing puller under the bearing to pull it off without damaging it if you need to add more shims.

The last photo shows a bearing hub sheared off because someone did not understand pre-load and locked up the bearing. Henry's 40 horses usually spin the bearing on the hub, however, in this case it sheared the hub. This actually came out of a running car. I have seen this on several occasions.

Best to use a shop press when installing the bearings. Hammering them on is not recommended. Be certain they are fully seated.

Tom Endy

Re: Diff assembly coming soon
 

I have used trial bearings to check set-ups in building gear sets in farm equipment where I worked. You hone out the trial bearing just enough to slip on the shaft and check for proper shims behind the bearing. Once you figure out what you need you instal the shims with the service bearing. Works every time.
This way you don’t use a puller to remove a tight fitting bearing and perhaps damage it. Makes quick work of a difficult problem. I’ve done hundreds of gear sets on farm equipment machinery this way. Pretty much just like Tom Endy describes in his wonderful article on rebuilding the Model A rear axle.
Fred

Re: Diff assembly coming soon
 

Hi fred. That's what I tried but I ended up with vastly different shim thickness compared to when I used the new bearings. At least that was my experience.

On a positive note, I put the pionion race in freezer and heated the banjo a bit with a heat gun. The race dropped in like a charm and is firm as can be now that the temps equalized

Re: Diff assembly coming soon
 

Hi Tom. When I took the pinion off I used one of the vendor wrenches for near the banjo and a large adjustable wrench on the outer one. That seemed to work to remove it at least

Re: Diff assembly coming soon
 

When you go to set the pre-load on the two pinion bearings, you will do it by adjusting the first nut to establish the pre-load, the second nut has to jam very tightly against the first nut to lock them in place. Sounds easy. Its not!

As you tighten the second nut it will alter the setting of the first nut. The trick is to get the two nuts jammed tightly together and have the correct pre-load. The pre-load is the same as the carrier, 20 inch pounds. My window of acceptance for both is between 14 and 22.

What I do is set the pre-load with the first nut to about 9-10 inch pounds and then tighten the second nut. It is trial and error effort. If you get it too tight you have to back off the nuts and tap the end of the drive shaft to loosen the bearings,

This is why it is important that the sleeve on the pinion be two dimensions. There should be .0015 difference. The first bearing should press on with an
interference fit. The second bearing should have the ability to move without too much effort. The originals are made that way. Some of the repos are not, and it best to have them machined or it will give you fits trying to set the pre-load.


The Ford service bulletins say to actually hammer the Ford factory wrenches to make sure they are tight. I am fortunate to have a set of Ford factory wrenches and that is what I do. They have long handles on them to give a lot of leverage.

Tom Endy

Re: Diff assembly coming soon
 

I ended up welding 12" extensions on both of my vendor supplied wrenches. It's a must, or you just can't get enough leverage.