After replacing all four motor mounts I set out to get the motor to v-drive alignment perfect. Trust me on this, new motor mounts and a spot on alignment eliminated all the vibration I was experiencing. No more pots and pans rattling in the galley. I now have smooth operation at any RPM from 600 to 2600.
I devised a simple way to measure the input shaft alignment and the u-joint alignment using a dial caliper. Input shaft alignment is the amount of offset allowed on the self-aligning bearing in the V-drive that the double cardan bearing rides in. Misalignment here will not cause vibration but will shorten the life of the bearing, cause the oil seal to fail and put a groove in your shaft. Walter does not give a specification for this, they provide an alignment gage. Here's how to measure this alignment with a dial caliper.
(http://i1121.photobucket.com/albums/l505/banjoband/vdhack1.png)
Using the depth gage on the dial caliper I measured from the outer ring of the cap to the shaft in 4 places.
Port = .505" Starboard = .538"
Difference = .033"
Next divide .033" (the opposite side of the right triangle) by 1.80" (the adjacent side of the right triangle)
Take the inverse Tangent of .033/1.8 = .01833 to get 1.05 degrees shaft offset to Port.
The 1.8" number is the distance from the measurement point on the shaft to the pivot point in the self aligning bearing inside the Vdrive.
Next I measured:
Top = .520" Bottom = .560" where the difference = .040"
Inverse Tangent .040"/1.80" = 1.27 degrees offset up.
Use the same trigonometry and the depth gage on the calipers to measure the U-joint alignment as follows:
(http://i1121.photobucket.com/albums/l505/banjoband/VDhack2.png)
On my gearbox flange I measured:
Top = 1.065" Bottom = 1.060" Difference = .005"
Offset in degrees = Inverse Tangent .005"/3.5" = .0819 degrees (motor tilted up a very small amount)
On my U-joint yoke the width is 3.5" (the adjacent side of the right triangle) your will probably have a smaller number.
Rotate the shaft 90 degrees and finally Starboard = 1.055" Port = 1.067" Difference= .012"
Motor offset in degrees to Starboard = Inverse tangent .196"/3.5" = 0.196 degrees.
Anything less than 3 degrees is within the Walter specifications. I was previously at 2 degrees and had significant vibration in the drive train. In this case I was shooting for zero and came pretty close. Note: You can get the inverse tangent from the calculator in any IPhone.
Pete
Pete,
As I get my ducks lined up for this shaft replacement I think I will plan to replace the engine mounts. Do you have mount recommendations and proceedural advice? I can see how to lift the front of the engine to get at those but how in #%?blazes do you lift the rear?? ???
By front I think you mean back. The
gearbox is forward. But I use DIY screw
Jacks. 5/8 all thread with nuts and washer
Between cylinder 1 and 2. Be careful.
Pete, can you elaborate? I can see being able to lift the front (transmission end) with a beam across the companionway and a come-along or Spanish windlass to get at the engine mounts on that end. What I am trying to understand is how to take the weight of the aft end(belts and pulley end) enough to get at those mounts. I am not following the screw jack idea... ???
What mounts did you use?
Pete, great post-thank you. the biggest question in my mind is...does perfect alignment really cure the rear seal oil leak on a 4-107? From what I have heard, nothing cures it. Does yours leak and did you do the alignment in or out of the water?
Jim
That is exactly what I am going to try to raise the front of the engine. We had no problem using a basketball to lift the combined 320 pounds of two people.
I will post some notes when I get to the engine mounts.
Quote from: PeteW on October 21, 2015, 12:11:45 AM
By front I think you mean back. The
gearbox is forward. But I use DIY screw
Jacks. 5/8 all thread with nuts and washer
Between cylinder 1 and 2. Be careful.
Pete,
Merry Christmas! Can you elaborate on how you use 5/8" all-thread as a compact screw jack to lift the front of the engine?
I am trying to use a deflated ball stuffed under the pan but need a 'plan "B"
Thanks.