What is the tollerance on a V-drive prop shaft

[alldodge]

Posted this in the non-engine and received nothing, then figured it deals with a Merc motor and velvet drive so maybe it should go here

Buddy has a 99 Maxium 3700 and when they pulled it out the port side prop shaft was sitting on the bunk between the hull and the strut. It was put back in, shifted and pulled back out. Put a dial indicator about a 13 inches from the hull and it showed .024 on the port side and .015 on the starboard. Measured the starboard to get a refference. The only way to get a accurate reading is probably pull the shaft out and check it on a flaf surface. Doest anyone know what would be the allowable tollerance for a 1 1/2 inch prop shaft?

 

[Bt Doctur]

Re: What is the tollerance on a V-drive prop shaft

If the shaft was bent you most likely would have vibrations.When you install a shaft you use wood blocks(door stops) to center the shaft in the shaft log, then adjust the motor to match that.. Alignment of flange to flange is (I think) .003 per inch of flange diameter.

 

[muc]

Re: What is the tollerance on a V-drive prop shaft

Need to know the length of the shaft to give exact number.
But a 20 ft shaft is only allowed .010 run-out.
Both shafts are bent and should be straightened.

 

[alldodge]

Re: What is the tollerance on a V-drive prop shaft

Thanks guys for the reply's, guess I'm in the right spot now.

The shafts are about 10 to 12 feet long. The port side shaft was removed part way to clear the trans so it could be pulled and replaced. This is the engine I posted previous about the 454 HO with a rod knock. Neither engine gave any indication of a vibration previous. The shaft was "supposedly" rotated every 90 degrees and it has no more then .003 run out. That being said, neither me nor my buddy have good feelings about the guy doing the work. If put back in the water and a vibration is felt it will need to be pulled and fixed. We are trying to find out how we should measure the run out prior to putting it back in the water. The strut is just a rubber water lubed bushing and if the shaft is turned by the prop or by a wrench different readings are seen. What is the correct method or is there one?

 

[muc]

Re: What is the tollerance on a V-drive prop shaft

The correct method is to support the shaft as close to the tapers as possible in V-blocks. Take two measurements one midway between the blocks and another right at the prop end of the shaft.
10 f.t shaft = no more than .005
12 ft. shaft = no more than .007
You must remove your hand or wrench and let the shaft come to a rest.
The quick way on the boat with the shaft installed is to set a dial indicator up on the very end of the shaft.

 

[alldodge]

Re: What is the tollerance on a V-drive prop shaft

The correct method is to support the shaft as close to the tapers as possible in V-blocks. Take two measurements one midway between the blocks and another right at the prop end of the shaft.
10 f.t shaft = no more than .005
12 ft. shaft = no more than .007
You must remove your hand or wrench and let the shaft come to a rest.
The quick way on the boat with the shaft installed is to set a dial indicator up on the very end of the shaft.

If were getting .014 and .025 in about the middle I hope it gets better when we get out to the end of the shaft. I would take it with the props off, put the dial indicator on the end, rotate 90 degrees, then let settle