How to reinstall shaft hub to prop shaft

[sdowney717]

With a great deal of difficulty I managed to remove the hub from the shaft. I used 4 bolts and a socket and slowly drew the hub coupler off the prop shaft. The shaft is 1/38 inch stainless.
It is a very tight fit and I dont want to hammer it back together. How is this normally done?
Do you heat the hub coupler or do you sand down the inner hub surface? Or is there a tool or trick to putting it back on the prop shaft. It was extremely tight and only came off with a lot of pressure using those 4 grade 8 bolts and nuts.

[Peter Malcolm Jardine]

I take it this is the coupler to the transmission you were taking off? It should be keyed on the shaft. See if there is any damage to the key. It should be perfectly square, if not, replace it. It should be tight, but not jammed on. A damaged key or key way is one place to look.

Another thing to check is whether the shaft turns fairly freely. If it doesn't, the cutlass bearing is probably badly worn. When this happens, the shaft turns hard, putting extra strain on the key when the transmission first goes into gear... making damage a long term probability.

You can emery cloth the surfaces involved, but it shouldn't fit so tight you have to heat it.

[ 12-05-2004, 09:16 PM: Message edited by: Peter Malcolm Jardine ]

[sdowney717]

Yes, and it is keyed with a SS Key. Both shaft and coupler appear perfect. The hub is sligtly rusty of course. So it should be a slip fit together and not a press fit?

[kulas44]

the gear flange is a press fit, do not sand any metal off. freez the shaft and heat the flange. use a hose clamp as a stop for the flange on the shaft, if done properly it will slide on easily so you need the stop to keep it from going to far. the two parts will equalize very fast and you won't have time for adjustments. rent a small bottle of nitrogen for freezing the shaft and heat the flange to a dull red. Have someone heating the flange while you freeze the shaft, just dribble the nitrogen on slowly. if you have any warts nows the time to get rid of them.

[Peter Malcolm Jardine]

That would be a slick way to do it, altho I usually make sure the surfaces are clean and free of burrs and use a carefully swung whompometer. :D

[kulas44]

I agree about cleaning both surfaces real good, but, a bent flange, even very slightly bent, will trash the output bearings in the trans, even if you don't feel any vibration. If you need to hit it with something use a wood block for a cushion, don't hit the flange with a hammer.

[Peter Malcolm Jardine]

Yep.. always.. but I like the nitrogen and heat trick. I will probably try it if the nitrogen is easily available.

[kulas44]

bout any welding supply place should have nitrogen, I have used propane before, just turn the grill bottle upside down and attach a hose to the valve, very dangerous, very flammable, not recomended but will work in a pinch. Liquid co2 is very safe. You could also check with your local veterinarian, they usually have some nitrogen on hand. If you have a good insulated container, like a coffee thermus, you could get it home ok. You won't need much. One of the local crackheads filled a 48 qt. cooler full of anhydrous amonia from a ag supply outlet, in liquid form, and put it in his back seat. When he hit the brakes it fell in the floor and vaporized, killed eem dead. good riddence

[kulas44]

ONTARIO, hell, just a regular winter day otta be cold enough there, you don't need no nitrogen!!!! :D

[Gary E]

I never needed the shaft cooled. As for the liquid nitrogen falling on the wood under the shaft, and it will.. is that a problem? One other caution, the guy with the torch had better be expierenced using it.

A much easier and safer method is to heat the flange on a hot plate, yeah it will take awhile but the heating will be uniform and thus the bore will expand uniform. The hose clamp as a stop is ok, but I use a C clamp holding a small block to the shaft as a stop. The C clamp is easier to prevent the shaft from rotation or give it a little rotation as the hot flange is sliding on and lining the key up.

I dont like using a torch near a wood boat, and if you wait to long from removal of heat to sliding the flange on the shaft, it will cool just enuf to stop it's movment 1/2 way to the desired position... One of Murphy's Laws.

[kulas44]

the hotplate is an excellent idea, as would be an electric bearing type heater/blower. I put a thick towel under the shaft to catch the runoff from the nitrogen. But any method is better than just floggin it on with a sledge. Probably just heat on the flange will do the job, but if it doesn't, and it's half way on then what? I was a heavey eqip. mech. for awhile and ruining a $1500 bearing putting it on a shaft was not an option- freez the shaft, you will be amazed.

[Gary E]

The towel sounds good...

I learned how to build machine tools from the at the time the worlds largest and best known company, many precision spindle bearings are heated on a hot plate without affecting the bearings heatreatment, then dropped on the spindle, keep in mind the dot's on the race radial position so the eccentricity is lined up correctly.

If the person is competent, and proper measuring tools used, the bore can be measured as it is heating, then when it's the proper Dia the instalation is is made.

And your right, no hammers allowed.

[ 12-07-2004, 08:07 PM: Message edited by: Gary E ]