Help removing gearbox from shaft.

Ralph Q

Ralph Q

New member
Trying to take cat pump with gearbox off of machine. I don't see any hole for a set screw and the gearbox is on there solid. Is there some trick to removing this thing from the shaft? Also Russ, What is a ballpark on rebuilding the pump? The gearbox looks immaculate on the inside and I'd like to use it. Is there other pumps that would fit it? 45G1. When I was running it, the oil was churning inside and then a pulse and the oil turned butterscotchy. You could see the the action through the site glass. Going to take the pump apart and check ceramic for cracks and seals for deformity.
 
Ralph Q said:
Russ, What is a ballpark on rebuilding the pump?
Click to expand...

That could be a pretty large ball park. Maybe $175 or so for seals only to $550 or so for seals, pistons, and valves.
 
Ralph Q said:
Hey Russ. Can I just pry this pump/gearbox off the shaft or is there something holding it on?
Click to expand...

There's no setscrew, it just slides on. I take 2 large screwdrivers and put them at 3:00 and 9:00 and pry evenly from both sides.
 
Russ Johnson said:
There's no setscrew, it just slides on. I take 2 large screwdrivers and put them at 3:00 and 9:00 and pry evenly from both sides.
Click to expand...

Well. I spent 3.5 hours trying to pry this gearbox off. All I managed to do is break a giant screwdriver, bend the housing on the gearbox, lose the site glass piece. And get po'd. Housing might have budged a 1/16 of an inch. Oh yeah I used wd40 specialist penetrator also. The is a slight bit of play that tells me the shaft isn't fused onto the pinion housing. Hey Russ ate you sure the shaft end isn't threaded into the opinion gear? There has to be something holding this thing on. I used crowbars...you name it, and I have some power behind me. I'm no lightweight.
 
Got any pics?

I am guessing you already separated the gearbox from the engine and pump?
 
Christopher said:
Got any pics?

I am guessing you already separated the gearbox from the engine and pump?
Click to expand...
Well first I started to take the pump off the gearbox. That came right off. Then I started to take the gearbox off the shaft/engine. It wouldn't budge, so I thought there was a set screw inside the gearbox housing that was holding the gearbox to the shaft, so I separated the gearbox housing(front/back) no set screw no place for a set screw. So basically I have the back half of the gearbox still attached to the shaft. I am so friggin' frustrated with this I can't believe it. I was wrestling with this stupid thing for hours
 

Attachments

  • IMG_20131018_201056_484[1].jpg
    IMG_20131018_201056_484[1].jpg
    1,008.7 KB · Views: 33
  • IMG_20131018_201104_615[1].jpg
    IMG_20131018_201104_615[1].jpg
    995.1 KB · Views: 32
You ever see how pulleys have another set of holes in them, you remove the bolts that hold the bushing in place and put them into the pulley and tighten them and that helps pull the pulley off of the bushing/shaft.

I wonder if you could so something similar?

Maybe put a nut with a large washer between the gearbox plate and the engine with a bolt going from the gearbox side into the nut so when you tighten the bolt into the nut, it pushes the bolt through it touching the washer or other piece of metal larger than the bolt so the pressure is spread out some and with several of these on sides of the pump, maybe that will slowly push the gear box off of the engine?

Kind of like using a gear puller but different as you are pushing from behind the gear box against the engine.

I don't know of the engine itself can handle the pressure, maybe it might using large washers or small plates of metal as the bolts themself are small and might punch through the engine, plates or large washers might avoid this.

Just an idea.

Good luck.
 
Sometimes if you spray the heck out of the shaft with a penetrant and use a wedge to apply pressure to the gear box (between the engine and gear box) you can leave it sit overnight and it will slowly release itself from the shaft so you can get it off in the morn. Otherwise I have busted up the housing and used a torch like russ suggested too.
 
Paul Kassander said:
Sometimes if you spray the heck out of the shaft with a penetrant and use a wedge to apply pressure to the gear box (between the engine and gear box) you can leave it sit overnight and it will slowly release itself from the shaft so you can get it off in the morn. Otherwise I have busted up the housing and used a torch like russ suggested too.
Click to expand...

That's exactly what I did. Busted the housing. Now its just the gear and the shaft. I sprayed into the keyway and all rust came out. Still can't get the thing off. Next step is the torch!
 
Well. It was a tough fight....but I finally got it! Sprayed with wd 40 specialist. Let it sit for a day. did that again for three days. Got extremely aggravated, Smashed with hammer in the opposite direction(hit gear towards engine flange) it went in! Then I pulled it back out and did that a couple more times and it came right off! Now I started it up and the engine is running rough. Time for a new carb. Anyone have experience with a gx390 carburetor?
 
Is the carb broken in some way? If not, they're pretty simple to rebuild. A carb kit might run 10-20 bucks. If it's really dirty (varnish build up...) then an ultrasonic bath may be in order.

Here's an example of what an ultrasonic cleaner can do:

 
You must log in or register to reply here.
Back
Top