OT 10 ton puller v 3 x 1/2" UNF bolts

[bob ward]

I needed to remove a rear hub from my '53 Hudson. The rear hub on these is a keyed taper, and if they've not been off for a while they can be fairly tight.

First I tried the modern sophisticated approach and set a 10 ton hydraulic puller on the end of the hub. I checked progress once a day and after a week figured maybe it wasn't going to work.

Today I tried the more traditional approach, ie a piece of 1" plate across the end of the axle with 3 x 1/2" UNF grade 8 bolts into the wheel bolt holes. I tightened the bolts progressively with a 1/2" rattle gun on 120psi air and the hub loosened at the point where the rattle gun was just about at maximum torque.

Clearly the 3 bolts were more effective than the puller, possibly the shock from the rattle gun may have helped.

My question to those who understand these things is thus. Do 3 x 1/2" UNF bolts used as described really deliver way more than 10 tons of pull, or is it more likely that my 10 ton puller doesn't really pull 10 tons?

[joeby]

Without doing the calculating, I'd say the impact had as much to do with it releasing the taper as anything. Did you try tapping the puller screw while it was tight?

Kevin

[bob ward]

No tapping (or banging or vicious hammering) allowed on these axles. There is a spacer block between the ends of the 2 axles which can be destroyed by the heavy handed.

[joeby]

I didn't see any mention of your tapping it in your OP, that's why I asked. Good to know of easily damaged parts before you start!

A taper can be very hard to release by just pulling. There was a complete write up on tapers that I read, don't remember where though. Usually vibration or a tap on the end of the puller screw makes it give up.

Kevin

[DICKEYBIRD]

Dunno 'bout Hudsons (other than the old Smokey Yunick reverse rotation marine camshaft Nascar Hudson Hornet story) but I did work on British Triumph TR3's, 4's, 5's & 6's (7's & 8's too but that's another grim story) that had the same style of taper-locked rear axle/flange.

The ONLY way to get them off (and remain reusable) was with the Churchill brand factory special puller. It was a huge chunk of steel that bolted onto the flange with 4 oversize lugnuts and a hardened cap that slid down over the threaded axle end. It also had a big ol' (1 1/8"?) threaded press screw with a fat ball in the end to apply the pressure. The axle, with the tool attached, was placed into a special cradle so the press screw could be tightened properly. By properly, I mean as tight as a young flat-belly could tighten it with a big, long 3/4" drive pull-bar with a piece of pipe slid over the end. Once it was tight, you took the thing out of the cradle and placed it onto the floor. You grabbed the shop BMFH, (10 lb sledge with a 3 ft handle) put your left foot on the top of the tool, wiggled around in your best Arnie Palmer impersonation, yelled FORE! and whacked the end as hard as you could.

Usually, one good whack would leave you with the tool & the flange underfoot and the axle skittering across the floor leaving sparks in it's path. I can't tell you how many of the things showed up at our door, brought in by local auto machine shops that had been ruined by giant hydraulic presses, torches, etc. Ahh, those were the days! We got half of $8.00 per side (1 flat rate hour) commission to pull 'em off and laughed about gouging the poor, tool-less unwashed masses.

[bighammer]

Stuck???????

Removing these taper bore hubs is quite easy, back off the nut and jam nut 1-1&1/2 turns, be sure to jam the lock nut tight or put cotter pin back in so hubs won't fall off. Take the damn thing to town and drive around town slowly for a few miles, go back yo the shop and yhe hubs will come off easily. Used to do this on late 40's-early 50's Cadillacs, works like a charm.


cookie

[DICKEYBIRD]

Them ol' Triumphs must've had an almost perfect Morse-like taper. We tried the trick you mentioned and they wouldn't budge...even after violent handbrake turns in the back lot!

Your trick would work (eventually) on rusty/seized up wire wheels though. We had a knock off hub nut for each brand with a hole drilled & tapped in the center. You remove the original, loosely screw on the drilled one using a washer-shaped gasket made from an old inner tube, pump it as full of Kroil as you could before putting in a pipe plug to keep the Kroil in. Then drive around in the back lot in circles, forward & reverse, stabbing the brakes often. It was best to do the viloent stuff with the brakes. They were cheaper to fix than the gearbox if you got too radical and broke something.

I've seen some that eventually had to be torched off though. It's unreal how rusted on they could get if the cust. didn't have his wheels removed & slathered with collodial copper occasionally. That was here in the mid-south...I can't imagine what a couple seasons of driving around in the salt belt would do!!

[bob ward]

Do 3 x 1/2" UNF bolts used as described really deliver way more than 10 tons of pull?

Hmm, there's never a mathematician around when you need one, I'll have to dust off the brain cells

Say a 1/2" rattle gun is good for 250 ft/lbs of torque, that translates to 12000 lb force at 1/4" radius, ie at the surface of the 1/2" bolt.

Helix angle of a 1/2" x 20 bolt is 2.865°, tan of 2.865° is .05

Vertical component at 2.865° of a force is force x tan, ie 12000 lb x .05 = 600 lb

There are 3 bolts, and assuming 1/3 friction losses I get a total pull of 1200 lb, call it 1/2 a ton. Have I got this about right?

If so my 10 ton hydraulic puller is definitely not pulling its weight, bad joke intended

[Timleech]

Hmm, there's never a mathematician around when you need one, I'll have to dust off the brain cells

Say a 1/2" rattle gun is good for 250 ft/lbs of torque, that translates to 12000 lb force at 1/4" radius, ie at the surface of the 1/2" bolt.

Helix angle of a 1/2" x 20 bolt is 2.865°, tan of 2.865° is .05

Vertical component at 2.865° of a force is force x tan, ie 12000 lb x .05 = 600 lb

There are 3 bolts, and assuming 1/3 friction losses I get a total pull of 1200 lb, call it 1/2 a ton. Have I got this about right?

If so my 10 ton hydraulic puller is definitely not pulling its weight, bad joke intended

I was told, many moons ago, by a friend who was a degreed mech eng, that thread pitch doesn't significantly affect the result. Can't remember why, maybe he was wrong. ISTR he was working for Lotus Engineering on the deLorean at that time

I've noticed that the grese-filled 'hydraulic' pullers which have been sold here since the year dot by Sykes Pickavant as 8-ton units are now being copied in the Orient and sold as 10-ton.

Tim

[Dawai]

Brass hammers make taper fits turn loose. DOn't have to hit them hard. THE harmonics of the ringing of the metal like a tuning fork shakes it.

Use a small brass hammer on the release wedge on your drill press, mill or and you will see what I mean.

It's the only way to make a set of HD flywheels turn loose and come apart without damaging them.

[wierdscience]

The old Jeep axles were the same way,in the 50t press it would take 20-25ton for then to part ways.I made a hat puller to fit the bolt pattern with a 3/4-16 bolt in the center to pull them.15 seconds with a 1/2" impact wrench and they came off.Definitely due to the impact more than the pull.

[quadrod]

i wish i still had the chart that gave the clamping force of a torqued fastener. i think the three bolts probably exceeded the ten ton force of the puller.

[Jeffw5555]

I just dug up a paper that was an empirical study of actual clamping forces of a torqued fastener, dry and lubricated. They found that an M5 X .8 fastener torqued at the rate of (effectively) 1 ft/lb equaled a clamping force of 300 lbs. This would mean a clamping force of 75,000 lbs at the 250 ft/lb torque you estimated. A M5X.8 fastener has effectively 31.75 TPI, so if I divide 20 TPI (for your 1/2 X 20 bolt) by 31.75, I get a "fudge factor" of .63. Multiply 75K X .63 gives me a clamping force of about 50K lbs, or 25 tons.

Significantly more than your 10 ton puller.

The fact that you used three bolts doesn't really multiply anything....draw it out as levers and you will see why....

However, like the others, I think that the vibration associated with the impact had much more to do with it......

[claudev]

Tapered Hub

Back in the good old days special pullers were made to ease this chore. Basically they were a 3 arm design which attached to 3 lug bolts and had a centered buttress threaded pusher about an inch in diameter, which screwed against the end of the axle. The key to its action was a hammer wrench on the pusher which, under the gentle influence of a large shop hammer, turned the pusher and forced the hub from the tapered axle. I never met a hub which couldn't be removed with this type although sometimes we might warm the hub a little with a "blue wrench" and "tap" the end of the pusher to ease things.

I had one once but gave it away about 1960 after I moved on from working on autos. I believe OTC made mine. No reason that you can't make one if you can cut a buttress thread. I suspect that ordinary threads would bind and/or strip in this application. Some of the antique car forums might be able to point you in the right direction. Alternately, find an old (70 plus) mechanic who worked prior to 1960. He might still have one.

[Timleech]

Back in the good old days special pullers were made to ease this chore. Basically they were a 3 arm design which attached to 3 lug bolts and had a centered buttress threaded pusher about an inch in diameter, which screwed against the end of the axle. The key to its action was a hammer wrench on the pusher which, under the gentle influence of a large shop hammer, turned the pusher and forced the hub from the tapered axle. I never met a hub which couldn't be removed with this type although sometimes we might warm the hub a little with a "blue wrench" and "tap" the end of the pusher to ease things.

New ones here (for UK):-

http://www.shacktools.com/sykespickavant-hub-puller-leg-p-1976.html?osCsid=19d7a0d419eb45784186c7fca6806c58

Not cheap though (S-P stuff never is)

Tim