Super Jet Midshaft Talk - Building, Rebuilding, SN vs. RN, etc.

Location
FRANCE
Only comes out between the 2 rear seals when you use the grease fitting.

When the shaft is out, you can grease everywhere by hand.
Precisely this is what I'm doing, when I use the grease fitting nothing comes out. It comes out there received_3815795658485501.jpeg

It can be obstructed ? Or the 2 rear seals are mounted too tight.
 

JetManiac

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orlando
How far is the rearmost seal pressed in? If it is pressed in too far, then yes it will be blocking the grease hole inside.
 
Location
FRANCE
How far is the rearmost seal pressed in? If it is pressed in too far, then yes it will be blocking the grease hole inside.
The rearmost seal is pressed 2mm.
I have an old midshaft housing and a rod get in IMG_20210226_224353.jpg in my new midshaft housing impossible to push in IMG_20210227_215137.jpg
 
Midshaft press-through is critical because this helps to determine the amount of spline overlap. The factory specified amount is 19.5-20.5mm as measured between the rear of the housing (not the rear of the seal) and the rear of the shaft.

View attachment 168745

When completing a build it is important to check spline overlap, especially with a/m hulls, custom builds, and setback pumps with a/m shafts.

Degrease both driveshaft and midshaft splines first. Install and align pump. Then put a small amount of grease only at beginning of the driveshaft splines and then install midshaft. Carefully remove midshaft and check how far the grease was pushed. Sometimes you need to repeat several times but this is the only way I know to accurately check spline overlap.

If you need to press shaft farther in to correct for a spline underlap, you can add an additional washer behind midshaft coupler to maintain alignment.

View attachment 168746

Got a few questions on a recent midshaft issue

The shaft removed from a 1990 superjet (100% original) doesn’t match shaft pushed out of 1998 Superjet. Nor is the 19.5mm achievable as shown by jet maniac. The shaft bottoms out long before 19.5mm sticks out. 1/4”++

#1. Did the 98 I got the shaft from have an aftermarket shaft that’s not to spec?
#2. Are they really different?
#3. Can someone measure a true known OEM 94-20 shaft

I find that the splines are about 6-7mm, at least, farther up or forward in the 94-20 shaft than the 00-03. Not technically enough drive shaft engagement

so I’m really hoping my 98 shaft must of been a typical junk aftermarket than oem.

however coupler mounting edge to end is identical on both so I’m guessing it’s intended for a superjet 94-20 regardless of oem or Aftermarket. It just isnt really the same size between models (wouldn’t surprise me) or a piss poor job of copying

see pic
 

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JetManiac

Stoked
Site Supporter
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Location
orlando
Got a few questions on a recent midshaft issue

The shaft removed from a 1990 superjet (100% original) doesn’t match shaft pushed out of 1998 Superjet. Nor is the 19.5mm achievable as shown by jet maniac. The shaft bottoms out long before 19.5mm sticks out. 1/4”++

#1. Did the 98 I got the shaft from have an aftermarket shaft that’s not to spec?
#2. Are they really different?
#3. Can someone measure a true known OEM 94-20 shaft

I find that the splines are about 6-7mm, at least, farther up or forward in the 94-20 shaft than the 00-03. Not technically enough drive shaft engagement

so I’m really hoping my 98 shaft must of been a typical junk aftermarket than oem.

however coupler mounting edge to end is identical on both so I’m guessing it’s intended for a superjet 94-20 regardless of oem or Aftermarket. It just isnt really the same size between models (wouldn’t surprise me) or a piss poor job of copying

see pic
The shaft on the right in your pic is definately not a 98 SJ RN shaft. The RN midshaft shaft has a shelf on it where the coupler washer rests that is larger in diameter than the shaft itself.
 

JetManiac

Stoked
Site Supporter
Vendor Account
Location
orlando
Got a few questions on a recent midshaft issue

The shaft removed from a 1990 superjet (100% original) doesn’t match shaft pushed out of 1998 Superjet. Nor is the 19.5mm achievable as shown by jet maniac. The shaft bottoms out long before 19.5mm sticks out. 1/4”++

#1. Did the 98 I got the shaft from have an aftermarket shaft that’s not to spec?
#2. Are they really different?
#3. Can someone measure a true known OEM 94-20 shaft

I find that the splines are about 6-7mm, at least, farther up or forward in the 94-20 shaft than the 00-03. Not technically enough drive shaft engagement

so I’m really hoping my 98 shaft must of been a typical junk aftermarket than oem.

however coupler mounting edge to end is identical on both so I’m guessing it’s intended for a superjet 94-20 regardless of oem or Aftermarket. It just isnt really the same size between models (wouldn’t surprise me) or a piss poor job of copying

see pic

This is a new OEM SJ midshaft for comparison. Your 98 shaft should look like this.

74EE949A-AD59-4367-80E7-A575A52340FA.jpeg

See the lip I was talking about
DE772F98-1B57-49D1-994E-963F63AEA0EE.jpeg
 
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