Help with 1937-40 rear axle rebuild

[Chester Leighton]

I'm getting ready to overhaul the rear axle in the 37 Pickup I got from my father. A little background on this. He had a 5 speed T-5 transmission put in it and an open driveshaft conversion before I got it. The truck had been converted to 1940 hydraulic drum brakes and a 1953 8BA engine installed before he got the truck. All that said, it still has a 4.44:1 rear end ratio. I don't know if the rear axle is 1937 or 1940 or if that even matters. I'm looking to put a set of 3.55 gears in the rear axle, replace the carrier bearings, thrust bearing, pinion bearing and outer axle seals. I've overhauled a model T rear end so I'm familiar with having to shim the axle housings to set the carrier bearing clearance and pinion gear lash. What I don't know is how do you know when you have the correct carrier bearing clearance? How do you know when you have the correct preload on the thrust bearing? Is there a book or some other info I can get that walks me through this? I've watched some U-Tube videos and they were helpful but didn't give me the detail I'm looking for. I also have a motors manual that I've read but again, doesn't go to the detail I need. Or, is there some where reputable near Lynchburg Va. that does this work?

[Ken/Alabama]

I’m in Alabama but you can probably find someone closer.

[deuce_roadster]

If you are familiar with the gaskets setting the lash on the ring gear and pinion, you should be able to do this. The 4.44 is from a V8-60. You will be quite happy with 3.55. I have a KRW pinion bearing setting tool. After setting a new pinion with it, I checked it with a calibrated inch-pound torque wrench and it was 30 inch pounds turning the shaft from the torque tube end. Keep in mind used gears are a bit trickier to set up. Go for new.
Good luck.

[bobH]

[QUOTE= Keep in mind used gears are a bit trickier to set up..[/QUOTE]

Interesting..... My preference has always been original, old, used, absolutely Ford script. 'Select' used, meeting my visual criteria. Just opinion.

[Brian]

the way I set the pinion preload [learnt this trick here on the 'barn] is to assemble the pinion/bearing setup in the banjo. Hold the spline of the pinion upright in a vise [so the banjo is facing up]...spin the banjo as hard and fast as you can...it should only rotate between 1/2-3/4 of a complete turn when preload is set correctly.

[JM 35 Sedan]

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The 3.54 gears with a 10 spline pinion are a bit difficult to find in good used condition, and nos is nearly impossible. Good used 6 spline sets are much easier to locate.
I would suggest doing a search in the archives here and on the H.A.M.B. - Jalopy Journal for threads on this subject. Some of these threads should lead you to full written procedures.
I've rebuilt a few of these rear axles ('35 - '40) for my own cars and some for my friends. It's not really that difficult of a job, but take your time, ask questions here, and get it set up correctly on the first try.

[cas3]

Good advise from John above ^^^ I only suggest you use google for the search. Seems to work better for me, Just do the search with " fordbarn" or " Hamb" included in the search. Example, I would try "differential preload fordbarn". Or similar . Brians method is what I shoot for when I do mine.

[Flathead Fever]

Here is one that sold on eBay for $73.00. Its missing its calibration spring so it's useless. Both KR Wilson and Manzel made them. I've only seen one of the Manzel's for sale and it looked like a nicer tool than the KRW. I have a KRW one but I'm too lazy to go out and dig it out and take a photo of it. If you were to get one of those pinion spine adaptors and then weld a quarter inch socket to it then you could use a modern inch-pound torque wrench to set the pre-load. Somewhere in my factory literature I saw the pinion pre-load specs but I don't remember what they were. The early factory instructions said to set the preload with the assembly in your hand, with a rag around the bearing race and then tighten the pre-load until the pinion bearing starts to spin in the rag instead of the bearing. Then they heated the housing and dropped the pinion assembly into center-section. That doesn't seem very scientific, I would prefer the preload tool with the inch-pound specs.

I've rebuilt rearends, maybe 200 or more at the phone company over 30-years but I have yet to do an early Ford. One of the things the old-timers taught me on the first one I did when setting the pinion preload was to get it set where it needed to be and then smack both sides of the pinion with a punch and big hammer. The bearing pre-load would loosen up. Then they would adjust it back to the pre-load spec and then smack it again. It would loosen up again. After a few smacks and minor adjustments, the pre-load would not change. We did this whether they used shims or crush sleeves. I would think with the races driven in until they bottomed out and bearings pressed on, they shouldn't have loosened with the hammer smacks, but they did.

[Terry,OH]

The above K R Wilson tool is missing it's special spring Do Not Purchase, beside there is no need for it. An inch/# torque wrench with a pointer is good. You can find Spec. and instructions in Ford Service Bulletins. T

[tippa77]

Hi
I change mine with help of VanPelt book , old gears was 4.44 now 3.54, i am happy and my flattie are too

[ford38v8]

The KRW preload tool is one that in my opinion, was never used by experienced mechanics back in the day. When I used it on my banjo, the indicator mark was acting so erratically that I couldn’t tell where it was set at all. I gave up, and took it to an old timer who set it upright in a bench vise and with both hands, gave it a whirl. By dumb luck, I had set it correctly myself, as with multiple spins, it would barely or almost make one complete revolution.
My gear set is a 3.78, which replaced a 4.44, which would have been a good set for parades, but I wanted a highway set. I’ve toured through 19 states and a bit of Canada with that gearset, which to me, proves the KRW gauge to be excess baggage.
In reading through the KRW catalogues, I believe that they went overboard on designing and producing a number of tools that saw little use at all.

[Chester Leighton]

Thank you for the responses. That covers the the input shaft thrust bearing pre load. How about the carrier bearing preload? How do I know when I have the housings shimmed correctly?

[Chester Leighton]

Also, I currently have a 6 spline input shaft. I have been looking at the Speedway catalog and they have new 3:55 ring and pinion gear sets that they advertise to fit this rear axle. I was also going to purchase new carrier bearings and the pinion and thrust bearings for the input shaft. I would think they have those as well?