| parrish | -- 10-14-2010 @ 9:03 AM |
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When I removed my passenger hub, the key fell out. Upon inspection, it has one beveled end. I figured that must be up and point toward the threads to assist hub install...To verify, I removed the driver side and don't see the bevel. Darn. So anyway, what is correct placement of the key and how far in from the threads is the key placed? Thanks for the help!
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| kubes40 | -- 10-14-2010 @ 1:06 PM |
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If you look closely at the axle, you'll notice the key slot is cut to an even depth from the outside (near threads) to very near the inside (closest to backing plate). At a point near the inside the slot curves up and outward of the axle. The radius'd part of the key goes DOWN and to the rear. Hope this helps. If you would like a detailed photo, let me know. Mike "Kube" Kubarth
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| parrish | -- 10-14-2010 @ 2:18 PM |
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Thanks, Mike. I'll see if I can spot the radius you mention. That makes sense with what I can observe on the still intact driver side...
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| TomO | -- 10-15-2010 @ 7:11 AM |
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If your key fell out, make sure that the key and keyway are not worn, The key should fit snugly in the keyway. Tom
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| supereal | -- 10-15-2010 @ 8:36 AM |
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Amen, Tom. If the keyway is damaged, the key will likely move out of place. To tighten it, place a large hammer under the axle and peen the edges of the keyway back into place until the key fits snugly. Be sure to carefully examine the ends of the keyway for cracks. Failure to fully clean the axle taper and hub, and/or to tighten the nut as far as you can, then skipping the retightening after a hundred miles or so can damage the keyway as the hub comes loose, leading to axle breakage and loss of control.
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| oldford2 | -- 10-15-2010 @ 9:04 AM |
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Parrish, Take it slow. Before you start beating on the keyway with a BFH, measure the existing key with a mic. Possibly the original key is long gone and someone replaced it with a piece of ordinary keystock. Maybe someone listening will give the exact size (.0000) and hardness. John
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| supereal | -- 10-16-2010 @ 10:00 AM |
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The same axle key was used from '28 thru '48. It is 2 55/64" in length. I wasn't advocating whanging away on the axle with a "BFH". The big hammer is to hold the axle if the keyway shows evidence of damage, usually a ridge of metal on each side of the groove, as the edges of the keyway are peened from above. Of course, the key, itself, should be examined for signs of shearing or other misshape. The key and the key way can be measured with a good digital caliper, but the real test is a snug fit. If you suspect the key is incorrect, replace it before you address the axle. They are less than two bucks.
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| Stroker | -- 10-16-2010 @ 2:13 PM |
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As Super say's you want a "snug fit". No one wants to lose a wheel, and I have had that happen with dire consequences. A properly fitted taper, correctly sized key and proper torque will mean that if the axle ever fails, it will do so just inboard of the keyway, and then ONLY if you dump the clutch in low with a big, "hairy" engine. Usually, you will peel the teeth off of the transmission cluster BEFORE you can twist off one of Henry's axles. The only axles I have seen fail in the keyway area were due to badly worn hubs, loose key's or improper axle torque. It used to be that you could go to your local parts store and buy "tapered axle shims". If you had a hub that didn't want to pull-up against the taper (would bottom the threads out first), you could wrap one of the shims over the end to take up the clearance. The point I'm trying to make is that if you have a good fit between the axle and the hub, and it is tight, the key really doesn't do anything. That tapered joint is stronger than the rest of the axle. The early "roundy-round",dry-lakes and drag racers would actually lap the hub to the axle with valve grinding compound to enhance this critical fit before they would install the key and torque the axle nut. A properly installed hub and fitted key will always require a puller to separate, and once separated, will require a drift punch to remove the key. Any slop in this joint, any you are essentially driving the car off the keyway, which is a recipe for having the axle fail prematurely right at the inside corner of the keyway.
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| parrish | -- 10-16-2010 @ 7:50 PM |
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Ok...2 questions. I will simply buy a new key, but should the key SLIDE into the keyway lengthwise or DROP into the keyway from above? And, what is correct method of torquing the axle nut? I do own an old spring type torque wrench, but is it more of an "armstrong" approach and then again after 100 miles or so?
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| 40 Coupe | -- 10-17-2010 @ 7:39 AM |
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the correct material for the key is common square stock. This is mild steel and not hardened. Do not use "key stock" the dimension for key stock is 0.253 and the key way is 0.250 It is very surprising how many of the old keys fall out but you can run into some that are very difficult to remove. For this reason and since your at the grinder making the key grind a slight taper on the front edge where the key and the bottom of the slot meet so a small wedge can be inserted to raise the key out of the slot.
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| supereal | -- 10-17-2010 @ 7:57 AM |
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Parrish: To tighten the axle nut, we use a breaker bar with a piece of pipe for an extension of the handle. After marking the end of the axle to show the position of the cotter hole, we put a new fiber seal in place, being sure that all of the old seal has been removed, add the steel washer, and tighten the nut as far as the extended wrench allows. If the slot in the nut isn't quite far enough to allow inserting the cotter, we actually stand on the wrench to get there. I know this sounds drastic, but in over 60 years, I have yet to twist off the end of an axle or strip the threads. There is a greater danger in having the hub come loose, which can result in a broken axle and loss of a wheel. There are locks available that fit the backing plate and contain the wheel in that event, but the chances of a broken axle are minimum if the hub is mounted correctly. Be sure to retighten the nut after driving for about a hundred miles. You may be surprised how much slack you find.
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| kubes40 | -- 10-17-2010 @ 9:07 AM |
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Don, I agree with Super on this one. Put a LOT of torque on that nut. I do it the same way and have yet to break an axle. Plus, the advantage of this method - if you do happen to break an axle, that axle was about to break anyway. Better while torquing than driving. If that key fits in loose, I'd suggest replacing the axle.
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| deuce_roadster | -- 10-17-2010 @ 9:59 AM |
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This would be a good time to remind those new to the hobby that the axle key is not there to drive the hub. The taper on the axle and in the bore of the hub is like the Morse taper on machine equpment. Many in our regional group lap the hub to the axle with valve lapping compound to make sure the fit is good. The friction of all that surface area is what actually keeps the axle from spinning inside the hub. As a teenager in the 60s I didn't understand this and ran with not enough torque on the nut with the predictable results. Another way to get the nut tight enough without using a 3' cheater bar solely is to tighten it up to about 100 lbs, leave the hub cap off, drive around the block and tighten it again. After a couple of times doing this the nut won't move easily and you can then use your cheater bar to advance to the next space to insert the cotter pin.
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| parrish | -- 10-17-2010 @ 11:35 AM |
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Well, I have also discovered some mild corrosion on the axle shaft itself along the taper, so I assume that is a problem. How big a problem? From what was said by duece_roadster, the corrosion will prevent (somewhat) the correct tightening/bonding of the taper between the shaft and the hub, thus reducing the friction required to drive the wheel properly. So, can I remedy the corrosion issue myself with careful 2000 grit hand honing?
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| Stroker | -- 10-17-2010 @ 3:43 PM |
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Yes, you can remove the corrosion safely this way. I would suggest that the presence of a little corrosion in this area is a good indicator that you had a good fit prior to taking it apart. The corrosion is evidence that there has been no relative movement between the hub taper and the axle taper. As I mentioned earlier, and deuce roadster has confirmed, a proper bond will result in no movement. The key is sort of the "belt" in a belt and suspenders doubly-d*mn*d-sure method of securing the hub to the axle. Henry adopted this method prior to the model T, and continued its' use through 1948 because it was reliable. Mopar and AMC also used this method for years. I would guess it would still be a popular method of attachment were it not for the convenience of being able to change an axle without taking the rear axle housing apart. As deuce roadster mentioned, most modern machine tools use tapered interfaces when stuff isn't supposed to slip. Like Super, I believe you simply cannot over torque an axle nut. I prefer not to use an impact wrench in this application as I want to "feel" the joint come up to contact.
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| parrish | -- 10-18-2010 @ 7:40 AM |
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Thanks for the info...In light of the friction factor, do you guys lubricate the axle shaft at all prior to hub install?
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| supereal | -- 10-18-2010 @ 11:12 AM |
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No. The axle and the hub tapers should be as dry and clean as you can get them. We give them a shot of brake or carb cleaner to be sure. The strength of the taper bond depends on full contact. If there is any evidence of damage to either side, it must be made smooth. If you find the bond doesn't form, there are conical shaped axle shims available.
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