| DuaneF | -- 04-11-2010 @ 8:50 AM |
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I am in the process of overhauling the rear end on my '35 P/U. When adjusting the lash on the differential bearings what is the appropriate torque for the axle nuts?
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| supereal | -- 04-11-2010 @ 10:29 AM |
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Place the right hand axle in its housing. Place the "spider" with free turning pinions into the case and the left half and axle are then bolted to the banjo without gaskets. Check the backlash of the axle gears by holding one shaft securely. Turn the other axle back and forth and measure the travel at the axle keyway. It should not exceed .010. After the drive pinion is installed, assemble the left hand axle housing with a .008 to.010 gasket. Install the right side using a similar gasket. Tighten all bolts. With a man on each side, turn the axles in the same direction. If the clearance is correct, a "heavy drag" will be felt (no torque value is given). If not, replace the right hand gasket with a .004 to.005. When correct, the backlash at the pinion shaft should be between .003 and .008. Ford was never great about listing torque values, other than for the engine internals. The old style Ford rear axles have survived for decades, in spite of this omission.
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| DuaneF | -- 04-11-2010 @ 12:01 PM |
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If I read your reply correctly; The right hand axle housing is initially attached to the banjo "without gaskets?". What holds the Carrier and the right differential bearing against the respective race? When the right hand housing is bolted to the banjo (temporarily?) doesn't the whole axle assembly, with ring/carrier just kind of float? How do you determine the right amount of lash? At the last minute in my overhaul (?),I have decided not to replace the ring and pinion as the installed ratio is just what I wanted (thought I had a 4:33 because of a 24 tooth turtle). The point being the pinion is already installed. The rest of your comments are appreciated. Last question, if you don't mind: I purchased replacement differential bearings, P/N 18-4221, but I just noticed the installed bearings are 68-4221. Aren't these for '37-'48? My P/U is a '35.
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| supereal | -- 04-12-2010 @ 9:50 AM |
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Duane: The axle and the ring gear/spider assembly is placed in the housings/banjo and bolted up without gaskets to measure the slack, if any in the spiders. This is done before the pinion is installed. As you are not removing the pinion assembly, you can omit the step. My book shows the correct housing bearings for your '35 as 18-4221. There usual problem with rebuilding an old rear end is to determine if it is, in fact, the correct axle for the year. Examine the old bearings for numbers to be sure. If you replace the bearings, also replace the races that go with them. All measurements of slack, etc, are measured with a dial indicator at the axle keyway or pinion spline. As long as you have considerable resistance when turning both axles in the same direction, as described, you should be OK. If too loose, or locked up, it will have to be changed. These rear ends are primitive, but tough, so don't get hung up on precision.
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| DuaneF | -- 04-12-2010 @ 10:25 AM |
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I agree, all of my documentation says 18-4221 bearings are correct and that is what I ordered. Howsomever, when I opened the new bearings it was obvious that they were different in size from those installed. With a magnifying glass and proper light I was able to see that they are in fact 68-4221 bearings. So I will reorder and press in the 68's when they arrive. Back to your proceedure: After rereading you earlier comment, is it correct that the initial effort is just to determine the backlash of the spider/axle mating? Once this is determined, and within tolerance attach the two housings, with gaskets (.008 - .010) to determine the preload of the differential bearings (drag)? How do you differentiate between the "drag" at the axle ends and the pinion/ring gear mesh? Or, is that just what you are trying to determine? I assume that with increasing the gasket thickness on one side and reducing the thickness on the other side by the same amount, you are shifting the ring gear/carrier into or out of mesh with the pinion gear. But what is the effect on the differential bearing preload? It would seem that on the thicker gasket side that preload would be less and vice versa with the thiner side. Or, am I guilty of overthinking this?
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| supereal | -- 04-12-2010 @ 11:57 AM |
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Once the preload is acceptable, the gear mesh should be OK as long as you add gaskets of the same thickness to the opposite side as removed from the other. The initial gaskets are to start to determine the preload. Once you have achieved that, the gaskets used, if equal on each side, will preserve that load. You can check the gear tooth pattern if you wish, but the pinion lash, as given, is a better indicator of when the ring/pinion mesh is OK. This whole thing is a bit like patting your head as you rub your belly. As said, the preload, once estabished is preserved by keeping the gasket thickness on each side equal. The pinion lash will be changed as the gasket combinations are tried, and is determined by the movement of the ring gear from side to side. I hope this clarifies the instructions. If it is any consolation, setting up big truck and modern car rear ends is much more complicated. The worst thing about old Ford rears is the necessary unbolting and refastening the axle housings to swap gaskets.
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| DuaneF | -- 04-12-2010 @ 3:48 PM |
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Thanks, that is precisely how I had it pictured once I was able to get beyond torquing the axle bolts for bearing preload. Speaking of torque, what is the right torque for the wheel hubs? I have read somewhere it should be about 220 lb. ft. Is this right? My torque rench only goes to 150.
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| supereal | -- 04-13-2010 @ 10:43 AM |
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Again, there seems to be no exact torque given for the axle nuts. When installing the hubs, first be sure that the axle ends are clean, dry, and free of anything that will interfere with the tapered hub, and that the keyway is straight and undamaged. Place the key in the keyway with the tapered end down and toward the inside. Work the hub into place carefully by hand as far as you can. Put a new fiber washer on the axle, the special steel washer, then the nut. We like to mark the end of the axle with a file to show the position of the cotter hole so we can find it after the nut is in place. Turn the nut down, using a "breaker bar". We use a piece of pipe on the wrench handle to increase the force. When you have tightened the nut as far as you can, check the holes in the nut in relation to the file mark you made earlier. If you have to change the position of the nut to insert a cotter, and can't tighten further, back off only enough to get the cotter in place, then spread the legs of the cotter. After driving the car at least 100 miles, retighten the axle nut, again as far as you can. I have stood on the wrench handle, and have yet to have an axle end or threads give way.
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