coupler gap huge, I dont think the engine moved

[Magnum Mike]

On a ride on Sun the coupler gap on my 90 SN has become large enough for the coupler to slip, but the engine mounts seem to be where they were when the coupler fit together correctly.

Is this a problem with the midshaft and midshaft bearing? Or something else? I haven't disassembled it yet, any ideas what I should replace while it's apart so I can order it today?

 

[demolition_x]

midshaft slipped or the bearings are shot.

 

[JetManiac]

Pull or move the engine forward, then remove your midshaft. The shaft should stick out the back of the housing about 19-20mm.

It is extremely common for us freestylers to jam the engine back so hard that it presses the midshaft much farther back into the bearing housing than it should be. It seems like I have to fix my midshaft almost everytime I pull my engine.

As long as the bearing housing rubber isn't torn through, your splines are still ok, and the midshaft bearing is good, then you can use a press and carefully press the shaft back to the correct spacing.

 

[Magnum Mike]

OK, I will pull it apart tonight and see what it looks like. Thank you both.

 

[SJBrit]

Make sure you keep track of your motor shims so you can put them all back in the same place. There may also be shims under the midshaft bolts so watch out for that. Keeping track of them now will save you from having to realign everything when you put it back together.

 

[Magnum Mike]

If the midshaft moves through the bearing housing and bearing by hand (no press required) is that a worn midshaft that needs to be replaced ? Nothing seems to be keeping the midshaft from moving too far back through the housing. A new bearing slides by hand on the midshaft too.

 

[restosud]

yeap,that's what it means.shaft is worn on the od.

 

[TJLSuperJet]

If that shaft is worn out, and slides throught the bearing, ordering a new one is a little tricky. They changed the midshaft in 92-93. Ive never had it slip back that far, but you should be able to just pull the carrier bearing out and hammer that shaft back to where you want it. I broke my midshaft and found that they dont make the one for the 90 sj, so i had to order the larger threaded one for a 93. the diameter of the shaft is the same, but the threads for the coupler were different sizes. so i had to buy a new coupler too...

My 2 cents......

 

[5810]

I have the same problem on my sj everytime i ride the ocean hit bottom, i just press the midshaft out and its good to go, check your motor mounts they might be shot, causing this problem

 

[Magnum Mike]

yep, I had at least two bad motormounts, replacing all 4. I'll order the midshaft today. I was told by the former owner the couplers were already non-original so hopefully the shaft is the larger thread.