Axle Key Installation

M

MABidwell

Junior Member
46 Super Deluxe

Trying to install rear hubs and I’m having trouble getting it to slide far enough over the axle to get the seal, washer and nut on to tighten it down. I’m assuming the problem is the key sitting too high - at least toward the inside where the taper is - meaning that I set the key back so far that the taper in the key isn’t lining up with the taper in the axle, so it’s riding high.

I’m attaching a couple of pictures and would like some advice on how to determine where the key should be located.

Alternatively, would it be a bad idea to file off the top of the key to get the hub to slide on?

Thanks,
Mark B
 

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The key looks like its fine, "sometimes" the drums can be really finicky and stubborn "Lining" up just right to fit over the bearing and the shoes (Make sure you adjust those in a little bit before you try to reinstall the drum) IF you haven't done that already.


A few of your threads LOOK like they have a little flat spotting on them, IF you have a die nut you "may" want to run that over them JUST to make sure they are good and crisp!!! AND CLEAN!!!
 
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From yout pictures, it appears that the key is extending outward, thereby raising that end above the flat bed of the keyway. Apparently, all keys are not equal.


On another issue, I suggest that you remove the key, and with the use of grinding compound, install the drum and nut loosely, turning the drum by hand to seat the taper to the drum. This step has been made considerably more important now since you apparently have used emery paper, which provides no control of the depth of cut. Failing to perform this crucial operation will put your key and keyway in control of the drum remaining in position, rather than the taper to drum contact, which by design is intended to solidly seat the drum against turning on the axle.
 
Chamfer the top edge of the key,it will help getting the hub on.
 

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You need to remove the key. Fit the drum to the axle with some oil or fine grinding paste. push it as far on as you can get it and accurately measure how far the axle protrudes. now fit the key and using a file keep removing metal from the top of the key where it touches (bearing blue or similar) until the drum goes on to the pre fitted position. The key does not need to touch the top of the slot.
 
How much play is in your axle in the above pictures???



Looking at your second picture you posted......IS it me OR is you axle not centered?? Maybe it's me BUT from your 2nd picture there "appears" to be more room at the top of the axle than at the bottom. MY 39 Mercury has a cork tapered axle seal that fit around the axle and "helped" keep the axle centered(AND rear bearing grease in). Hence my first post, EVEN with that axle seal the axle "sometimes" is still not 100% centered and getting the drum in the right spot over the bearing, shoes and axle centered (per se') takes a little maneuvering to get all 3 to line up and play friendly!!!!


38fordV8...I'm not following you on your keyway theory, could you explain it again or maybe differently....judging by the taper of the axle the keyway "looks" to be in and flat all the way across. NOT to be arbitrary or argumentative.
 
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rockfla, the axle will never be centered until the drum is installed with its bearing.


Position of the key in the pictures may be an optical illusion. Keys must be aligned and fully seated within keyways.
 
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ford38v8 said:
rockfla, the axle will never be centered until the drum is installed with its bearing.


Position of the key in the pictures may be an optical illusion. Keys must be aligned and fully seated within keyways.
Click to expand...
RIGHT
AND UNTIL he centers the axle the drum will not fit and "possibly" give the appearance of it being a "key way" Issue. THEN add the ability to get the drum over the brake shoes....ESPECIALLY IF they weren't adjusted inward when the drum was pulled, FURTHER limits the location (and the ability to move the axle and drum) relative to the bearing!!!
I Fought this exact issue on the right rear of my Mercury for at least 10 mins before IT slipped on just as it should.



AGAIN (I have a lap top so its easy to turn it sideways) BUT Look at the gap on the top relative to the bottom and where the axle is positioned.....IF he is trying to slide the drum on as its pictured and doesn't know that the axle HAS to be centered, key way OR Not....The drum isn't going to fit!!!! 2nd picture
 
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Also one of our local V8ers had the top inside edge of the key 'grab' the hub. reason for an inside top taper? Newc
 
Rock, the axle floats to a certain degree because the bearing is in the hub. There is a seal inside which the axle rests on, so if tapping the key in place it is important to hold the shaft up so you are not hammering on the seal.
It is sometimes helpful to look down the hub hole to see the keyway lining up as you slide the hub on.
There should be a taper on the key. This needs to be positioned correctly so the key will sit down snugly into the keyway.
Hubs should be lapped to the shaft. Hub bore and shaft must be spotlessly clean before assembly.
Hub should fit to same position with or without key.
Nut must be maintained eyewateringly tight.
Mart.
 
Have you tried a different key? It looks to me like the end of the key closest to the threads sticks up higher above the taper then the end nearest the bearing. Is this a new repro key? If so, it could be junk.
 
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Don't forget the fact that the keyway slot itself tapers-up to meet the axle surface at the inner end, as shown here. Hence, the need for the key itself to have a taper facing downward to accommodate fitting the ramp at the inner end of the keyway. Also note the fatal crack in this axle, more than likely caused by NOT tightening that big nut tight enough. DD



216277
 
Thanks to everyone who offered advice.

I stopped working on it yesterday thinking that I might have to replace a damaged axle - so dismantle everything I've spent the past few months working on!

This morning, I re-read the comments along with a few more that had been posted and went back at it. Little by little, taking some material off the key, I was finally able to get the hub to fit on far enough that it seemed like it was good. The other hub didn't cause me any trouble at all, so the comment that "not all keys are alike" rings true.

Thanks again!

Mark B.
 
MABidwell said:
Thanks to everyone who offered advice.

I stopped working on it yesterday thinking that I might have to replace a damaged axle - so dismantle everything I've spent the past few months working on!

This morning, I re-read the comments along with a few more that had been posted and went back at it. Little by little, taking some material off the key, I was finally able to get the hub to fit on far enough that it seemed like it was good. The other hub didn't cause me any trouble at all, so the comment that "not all keys are alike" rings true.

Thanks again!

Mark B.
Click to expand...

Dont forget to pull this up real tight with nut. 200Ft/lbs!!
Phil NZ
 
or running the taper up and outward. or just up. The tapered end is not so you can get the hub on easier in my opinion. It is used to increase bond as the axle is tightened to 200lbs.


If the axle key is installed with the little end out and/or taper up of the axle it is on wrong in my opinion.
 
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Tinker said:
or running the taper up and outward. or just up. The tapered end is not so you can get the hub on easier in my opinion. It is used to increase bond as the axle is tightened to 200lbs.


If the axle key is installed with the little end out and/or taper up of the axle it is on wrong in my opinion.
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Tinker, I’m glad you used the term opinion, because in my opinion, your opinion as stated in the first sentence is wrong, and here’s why: the taper needs no help to increase bond, and in fact, any force exerted by the key would decrease bond between hub and taper shaft, as any interference between shaft and hub that operates to exert an unequal force around the circumference presents an opportunity to break the bond between the two surfaces. I’m no mathematician, and I haven’t put a micrometer on a key, but I’ll lay odds that keys were not intended to be an interference fit between axle and hub, and that someone here will come up with the Ford specs to confirm the point. If you just think about it, if your theory were correct, the tolerances required of all related components would boggle the mind. My opinion then, total depth of matching keyways must exceed the height of the key.
 
ford38v8 said:
Tinker, I’m glad you used the term opinion, because in my opinion, your opinion as stated in the first sentence is wrong, and here’s why: the taper needs no help to increase bond, and in fact, any force exerted by the key would decrease bond between hub and taper shaft, as any interference between shaft and hub that operates to exert an unequal force around the circumference presents an opportunity to break the bond between the two surfaces. I’m no mathematician, and I haven’t put a micrometer on a key, but I’ll lay odds that keys were not intended to be an interference fit between axle and hub, and that someone here will come up with the Ford specs to confirm the point. If you just think about it, if your theory were correct, the tolerances required of all related components would boggle the mind. My opinion then, total depth of matching keyways must exceed the height of the key.
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Damn, Dude.....You've got a way with words every now and then....Nicely-Put!
And, most of the time at this place, we don't need no stinkin' OPINIONS. With MOST of the matters that we usually discuss here, many of the opinionated answers that some want to throw out there straight from the butt usually confuse matters, or at worst, give a new member or inexperienced old Ford owner a totally incorrect idea for what he's asking. You GO, Alan! DD
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Most user tightened axle nuts I have removed have been WAY too loose and the hubs usually don't need my KRW puller. Like the picture Dick posted I have removed many cracked axles that were still in service. If you look at the ends of broken ones you can see that they were cracked for a very long time. It is a good thing the axles were made of good steel and were many times stronger then the minimum needed. Educating new owners of the idea that the hub is driven by the taper and not the key is something I feel I should always do. I also suggest using crack detection methods when the hubs are off of a vehicle you don't already KNOW the condition of the axles.
 
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