Coupler gap, how much is to much?

Aaron Jaworowski

Aaron Jaworowski

Location
Rockford Michigan
Just tossed the motor back in my 96 superjet and noticed there was a nice size gap between the two couplers. Is this to much of a gap? And if so any idea what caused it or how I can fix it? The motor is pushed all the way back. Thanks everyone ImageUploadedByTapatalk1418871949.706500.jpg


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Harbor

Harbor

Location
Stockton
Spec is 2 to 4 mm, if your way beyond that most likely the midshaft has moved deeper into the midshaft housing.

the midshaft should hang out the back of the midshFt housing 19.5mm to 20.5mm
Any deeper and you'll have excessive coupled gap.

I have a 96 RN down stairs I recently pulled the engine on and I noticed A large gap as well, off the top of my head and from memory it looked similar to yours but didn't measure it.

What's yours at now?
 
Harbor

Harbor

Location
Stockton
Yes but first measure your coupled gap. If it's beyond spec remove the midshaft housing and measure how much the shaft protrudes from the housings matting to hull bulkhead surface. press the shaft back towards the engine to correct your coupled gap the by the amount needed or to the 19.5 spec
 
Harbor

Harbor

Location
Stockton
The ski clinic has a how to. YouTube video on pressing the midshaft but I can't remember if it a stand alone video or part of the pump install video. Might help you to watch it.

I think I adjustem mine on e with a brass hammer too
 
Harbor

Harbor

Location
Stockton
They Are not pressed in that tight. Couple good slams trying to push the engine all the way back could move it.

What's your gap in mm ?
 
Harbor

Harbor

Location
Stockton
That would be almost 10mm so you need to Adjust it. If you can't measure in mm just convert it. Like mentioned Id determine your coupled true gap with engine bolted down then slide your engine forward enough to remove the midshaft and measure the shafts protrusion and adjust the midshaft into the housing to correct your gap

I did a minor adjust on mine with a brass hammer. The ski clinic video would help you I think
 
Harbor

Harbor

Location
Stockton
Iam glad you posted about this issue. Now I remember when I changed the midshaft housing in the ski in my avatar I didn't have enough gap and didn't like where my bed plate holes lined up with engine mount holes so I slammed the engine hack a few times to push the midshaft deeper Into the housing just a tad.....

Now the ski I have apart with two much gap needs fixing as well, I saw the gap but didn't think what could cause it but now I realize it may be caused the two bad engine mounts I found, too much engine movement is pushing the midshaft deeper
 
Aaron Jaworowski

Aaron Jaworowski

Location
Rockford Michigan
I took the mid shaft out and measure it and sure enough it did get pushed in. I was able to tap it back out to 20MM. It really surprised me that the shaft could push in like that.


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Harbor

Harbor

Location
Stockton
Engine vibration or a failing mount?

The Iam working on did the same

Edit: add couple/engine misalignment to the list, if they are not square to each other. "Same gap all the way around"
Then as they rotate they would want to sepetate so to speak as they rotate, the engines not gonna move so the shaft would have to
 
Last edited:
JetManiac

JetManiac

Stoked
Site Supporter
Vendor Account
Location
orlando
Harbor said:
Engine vibration or a failing mount?

The Iam working on did the same

Edit: add couple/engine misalignment to the list, if they are not square to each other. "Same gap all the way around"
Then as they rotate they would want to sepetate so to speak as they rotate, the engines not gonna move so the shaft would have to
Click to expand...

Same gap all the way around is only part of the alignment. The couplers need to be aligned in height and side to side as well.
 
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