crankshaft misaligned

[jetrod]

While chasing down a drive train noise I have found the crankshaft is not centered by about .015 in the horizontal. Dial indicating the recess in the flywheel housing reflects this and dial indicating the dowels that locate the flywheel housing also reflects this. So my transmission and motor (crankshaft) are offset by .015. Is this the source of my drive train noise? I have ruled out the differential and the transmission is recently rebuilt. Will the misalignment eventually effect the transmission? Thanks in advance, Jerry

[RawhideKid]

Just a couple questions.

First, where are you taking the measurements from?

Second, what was the actual noise you were chasing down?

Usually if the flywheel housing is lopsided it can cause noises as well as the trans jumping out of gear and other strange anomalies.

[Synchro909]

If the crank shaft is out by that much, how is the mesh between the crank gear and the gear on the cam shaft? It would be either too tight or too loose and would either destroy the gears or make lots of noise. Could that be the source of your noise? Lawrie, where are you??? (FB member Lawrie has had experience with this)
It could also cause a misalignment of the gearbox input shaft which might also cause a noise.

[40 Deluxe]

It could also be a sloppy, cheap crankshaft regrind. El Gypo regrinders don't use the original centerline of the crank to grind from, they take an average of the worn journals to save time and wear on their grinding wheels, giving you a second class job and them more profit.

[jetrod]

Originally Posted by RawhideKid

Just a couple questions.

First, where are you taking the measurements from?

Second, what was the actual noise you were chasing down?

Usually if the flywheel housing is lopsided it can cause noises as well as the trans jumping out of gear and other strange anomalies.

Magnetic dial indicator mounted on the crankshaft--the noise sounds like "loose gears or worn bearings" in the transmission. The transmission has not jumped out of gear yet, but I expect it will.

[jetrod]

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Originally Posted by Synchro909

If the crank shaft is out by that much, how is the mesh between the crank gear and the gear on the cam shaft? It would be either too tight or too loose and would either destroy the gears or make lots of noise. Could that be the source of your noise? Lawrie, where are you??? (FB member Lawrie has had experience with this)
It could also cause a misalignment of the gearbox input shaft which might also cause a noise.

The front of the engine is OK, the cam gears mesh with the proper "lash",so the crankshaft is most likely skewed. Yes, the gearbox misalignment is what I am concerned about and think is causing the noise.

[Brian T]

If you are measuring the outside edge of the flange that the flywheel sits on, the engine should be vibrating like crazy, probable all the way back, it is not unusual to be fooled by vibrations in the rear when something is amiss up front, not much chance of reversing that run out, if it was that far out at the front I would image the T,gears are long gone, keep us posted.

[jetrod]

Originally Posted by brian t

if you are measuring the outside edge of the flange that the flywheel sits on, the engine should be vibrating like crazy, probable all the way back, it is not unusual to be fooled by vibrations in the rear when something is amiss up front, not much chance of reversing that run out, if it was that far out at the front i would image the t,gears are long gone, keep us posted.

what!!!!!

[Tom Wesenberg]

Originally Posted by jetrod

what!!!!!

Some crank grinders don't know that the flywheel flange MUST be concentric with the rear main bearing, or the engine will have a bad vibration. A 62 pound flywheel plus the pressure plate weight being off center by several thousands of an inch can make for a good paint mixer.

[RawhideKid]

Originally Posted by jetrod

Magnetic dial indicator mounted on the crankshaft--the noise sounds like "loose gears or worn bearings" in the transmission. The transmission has not jumped out of gear yet, but I expect it will.

I understand the item you are using to measure with.

What I am asking is where are you getting the side to side measurement from?

The flywheel housing, the motor mount flanges, the frame rails?

If you look at the pilot shaft bearing/bushing in the flywheel is it oval, or distorted/worn on one side or the other?

Do you have a pilot shaft to place in there or an ID mic to measure it with?

The misalignment that you have could cause a howling in the trans that would sound like the gears or bearings were shot.

[PC/SR]

A horizontal misalignment would seem to me to be an align bore problem. I do not understand the measurements you refer to. I do not know what measurement you refer to about the "recess in the flywheel housing" or where you measured that from. I do not see or understand what reference you have to compare the front of the crank to the rear of the crank. The crank/cam gear lash is not an indicator of crank alignment. Nor do I understand a dial indicator mounted on the crankshaft, and what it references to front and back. IMHO, the only true measurement of crank horizontal alignment would be distance from the deck to the bearing saddle top. The pros would know better than me. Babbitt or insert? Have you looked at the flywheel housing shims?

[nick c]

Heres what I think we know.
1 the engine is on a stand and it is vertical.
2 the recess is where the bell housing meshes to the FW housing.
3 the dial indicator is sitting on the crankshaft flange while rotating.
4 the tir = total indicator reading is .015 which is actually only .0075" off center and the dowel pins in block are also off.
If you place the magnet base indicator on FW housing and turn crankshaft, what is the tir divided by 2.
carry on nick c

[Kohnke Rebabbitting]

The crank should set dead ZERO between the front, and rear main bolts. Variance should never off more then, 1/2 to 1 thousandth out. Once set, it should be kept there while setting the gear mesh, and the rear crank main at the same height as the front, so the crank is level. If the rear of the crank is off, you are going to have big gaps for oil leakage

Every thing counts, balance, Aluminum oil slinger, Flywheel housing, Pilot shaft, ect.

Herm.

[jetrod]

Originally Posted by nick c

Heres what I think we know.
1 the engine is on a stand and it is vertical.
2 the recess is where the bell housing meshes to the FW housing.
3 the dial indicator is sitting on the crankshaft flange while rotating.
4 the tir = total indicator reading is .015 which is actually only .0075" off center and the dowel pins in block are also off.
If you place the magnet base indicator on FW housing and turn crankshaft, what is the tir divided by 2.
carry on nick c

Yes, you have it right except the reading is .035 which divided by 2 is .0175. I'm sure the crank is off center and I'm looking for a repour of the mains. Thanks for the input.

[jetrod]

Originally Posted by Kohnke Rebabbitting

The crank should set dead ZERO between the front, and rear main bolts. Variance should never off more then, 1/2 to 1 thousandth out. Once set, it should be kept there while setting the gear mesh, and the rear crank main at the same height as the front, so the crank is level. If the rear of the crank is off, you are going to have big gaps for oil leakage

Every thing counts, balance, Aluminum oil slinger, Flywheel housing, Pilot shaft, ect.

Herm.

Thanks, Herm your input is appreciated. That is the kind of info I needed. The hobby needs your kind. Jerry

[Terry, NJ]

Going back to my mahogany speed boat days, The C-line (Centerline) of the crank must be perfectly aligned to less than .003 with the prop shaft, And this is with a stuffing log and a rubber strut bushing! If you don't achieve this in both a vertical and horizontal plane, the whole thing will vibrate incredibly.
Terry