Midshaft details; gp760 vs. 96rn

[user_error]

I have 2 midshaft housings in front of me. One is from a gp760 and the second from a 96 rn.

The silver housing with the superjet shaft pressed in is the gp760 housing.

The green housing is an oem 96 rn housing. I was under the impression that the housings were the same, but the depth at which the seal sits and the type of seal seems to vary between the two. As far as I know the gp760 housing is original and never rebuilt. Same with the RN housing.

Is it acceptable to use the gp760 housing with a superjet shaft? Why the varying seal type and depth?

The one pictured below is the oem gp760 housing that i pressed a sj shaft into. Notice how the seal sits much more recessed into the housing itself.








this picture is a oem SJ midshaft and housing. Notice the seal depth.



Am i missing something? It appears as if the housings share similar dimensions in all other aspects except for the front seal.

Calling midshaft experts...please help

 

[OCD Solutions]

I never really gave that aspect much thought before but I googled them and see plenty of pics both ways.

The inside bore is the same so the only difference will be quantity and spacing of the bearings and seals that are pressed into it.

 

[user_error]

The midshafts use the same bearing ID, so the shafts are interchangeable, but the RN shaft and gp760 shaft have steps on them suggesting that the shaft sit in the seal at a certain depth.

It almost appears as if the sj shaft in the gp760 housing is not contacting the seal. The shaft also has the tiniest amount of play in it when pressed into the housing. It seems normal, however, because the gp760 shaft pressed into the sj housing feels the same.

Has anyone ran this particular arrangement?

 

[JetManiac]

The second pic you show is not an oem sj setup. The housing has been changed or rebuilt with a wider bearing and/or clips were installed wrong. The front seal should be recessed some on sj setup like below.

 

[OCD Solutions]

Some of the 650's appear to be done that way,maybe whomever rebuilt it, used the specs, (or an old one for reference), and copied the setup.

Here's a pic off of ebay for a 17H16 Yamaha Wave Runner 3 650 1991 Midshaft Housing, Bearing 6R7-W4531-00-9M

 

[user_error]

Some of the 650's appear to be done that way,maybe whomever rebuilt it, used the specs, (or an old one for reference), and copied the setup.

Here's a pic off of ebay for a 17H16 Yamaha Wave Runner 3 650 1991 Midshaft Housing, Bearing 6R7-W4531-00-9M

the oem RN housing i have shows the front seal sitting flush with the lip like in the picture you posted (i know its a squarenose one, but the point im trying to make is the seal depth). The engine had never been removed from the ski before i got it, which is what seems odd to me considering what Jetmaniac said.

@JetManiac, the SJ shaft is stepped in certain areas. I pressed the shaft through 20mm on the backside of the midshaft, per the information in your helpful Midshaft info thread. When pressed through 20mm, it seems as if the shaft can slightly wobble in the housing, despite it being tight in the bearing. Is this normal?

 

[JetManiac]

The midshaft bearing is single row bearing so it will allow some 'wobble', maybe this movement is what you are feeling?