Other Blaster/ SJ Midshaft housing rebuild important Tip !

Freakrider

Freakrider

X247
Location
Tampa Bay area
After wondering for a long time why a rebuilt Midshaft with a new OE Koyo bearing was heating up to untouchable temp in 30 seconds of idle on the trailer, the answer finally jumped out and hit me in the middle of the night.:no: NEVER use a double lip seal for the front seal like the parts finder shows on the older green housings. The double lip drags on the shaft creating extreme heat. All I did was pop the second lip off and cut it off. The silver colored midshaft housings have the single lip seal in front. I did read many threads and never ran across this. This is prolly why blasters with the green housings get hot. The double lip seal is used in the very rear as the last seal and the rear is cooled by water. If the housing rubber looks good I say put a new Japan Koyo bearing in it keep it greased between the seals and it will last a long time. Also contrary to popular belief the Koyo bearing is not a true sealed bearing, you can pop the bearing seal off and on to grease repack a used good bearing. Hope this helps someone in the future...

Thoughts/comments ?
 
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Freakrider

Freakrider

X247
Location
Tampa Bay area
augustaf said:
Duh! Double lipped seals do not heat bearing housings.
Click to expand...

It sure did in my case ! I removed second lip and the heat up quit, nothing else moved or changed. Yamaha changed it for a reason with the newer housings.

How many people check there midshaft for heat build up ? I would say few...
 
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augustaf

augustaf

Location
central florida
The first 2 Superjets- 90 & 91 - had dbl. lipped seals in front, later models only used them in the rear of the housing. I don't recall if housings got hot on the early ones or if that even would have been a problem. In 92, Yam also installed the lube fitting and hose to delay water entry. Shortly thereafter they sold repair/retrofit kits containing an updated, larger shaft for SJ, a shaft for WR III, a bearing housing with frnt seal installed and the lube hose with fitting, all that rather cheaply - about $100 (?). I bought a few but they discontinued that kit in 95. I doubt that any original (not updated, repaired or changed) 90 & 91 housings are still in operation. Rusted bearings would have failed by now. Since 92, a single lipped seal , is used on both sides of the bearing, regrettably Yam does not update their parts lists to reflect this running change on the older models.
 
Freakrider

Freakrider

X247
Location
Tampa Bay area
this 94 blaster green midshaft housing shows a dbl lip seal in front...I bought this used complete blaster midshaft and housing, it was running untouchable hot in 30 secs (even with the pump out). It is rebuilt with new OE parts and was still running the same hot until I removed the double lip seal. It was running hot in a blaster and then a SJ. It now has zero heat in a 30 secs run.

http://216.37.204.203/yamaha_OEM/YamahaPWC.asp?Type=13&A=32&B=7
 
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J

jpswift1

Location
Buffalo, NY
I know this is a very old thread, but I was just ordering new seals for my Waveblaster midshaft housing and according to the OEM parts diagrams, the 94 and older midshaft housings called for 2 double lip seals.......one for the font and one for the back/rear side of the midshaft housing and a single lip seal for the inside. In the 95 and newer OEM parts diagrams it calls for a single lip seal on the front and the inside, and a double lip seal on the back/rear side of the midshaft housing.
 
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