Flywheel coupler for John Deere 690b

[Gerald Chungus]

Hello all, Im new to the forum and was wondering if someone can help to locate the rubber driveline coupling for a 690b excavator. It is no longer available from John Deere and I cant find it at any salvage yard. The main pump was leaking and must have degraded the rubber over the years. Im having that rebuilt hopefully by a local hydraulic repair shop. The owner says he can still get the parts for it. I'll post back about that as Ive read comments that parts are not available for those tyrone pumps. Thanks in advance.

 

[mg2361]

Welcome to HEF Gerald!

 

[Gerald Chungus]

Thank you Mg, the splined hub is still ok. Im looking for the part that is sandwiched between that part and the flywheel. #8. Also, I one of the bolts, #6 it was broke off in the crank, but I know I could get a generic 1/2" bolt when I get the stud extracted.

 

[Gerald Chungus]

I tried to drill out the broken bolt with left handed drill bits but one broke off.

The flywheel and housing were moved forward and 2 nuts were used on exposed threads then backed out the broken bolt. The crank seal was also replaced with NOS john deere part # RE17352 I found on ebay. I bought an aftermarket JDG 476 Crankshaft Rear Oil Seal Installation Tool Set on ebay. Although Im sure the JD tool is exact, the knock off seems to have installed the seal perfectly. A thin coat of permatex aviation sealant was used on the edge of the crankshaft flange before installation of the crank wear sleeve/oil seal.

I still cant find the coupling and waiting on rebuild parts for the pump.

 

[hosspuller]

Rubber coupling looks like the same as used on my Deere F915 mower. My coupling while smaller (only six bolts) is still available from Deere. You might try to track down the manufacturer for a replacement. Likely the bolt circle is the only critical dimension. And anything close would fit.

 

[Gerald Chungus]

Looks like I found something that will work. Part # LCR 400 800 135A made by Deltaflex of Racine, WI. I bought it through their distributor, Mid Atlantic Rubber Co. in Baltimore. They are great to work with and only charged $150 for the part. John Deere part #s for the coupler are AT 50733 or AT 84168, list price was $775 when it was last available! It will need some modification of 4 of the bushings so Ill post about what needs doing, but width and bolt pattern look right. I should be able to use a drill press to countersink the bushings for the bolts threading into the splined hub. From my research, the same part was used on 690A and 690B excavators.

 

[hosspuller]

When you machine the bushings be careful not to spin the metal bushings in the rubber. They're just cylinders molded in with nothing to retain them in the matrix. ( I took my old coupling apart )

 

[Gerald Chungus]

Thanks hosspuller. Thats a good point. I could see a drill grabbing at those very easily. Going to be real careful but might wind up cussing up a storm.

 

[Gerald Chungus]

We drilled out the holes back in the end of April and I cant remember the drill size. The bottoms were made flat at a depth of 3/4" with a woodworking bit that was laying around. It was not easy because we had to keep the hole center with the rubber flexing while drilling. The coupling was bolted in two places through some of the other holes to the drill press. After a couple hours it was done and the hub was mounted with the factory allen bolts and blue loctite at 85 ft lbs. The hex bolts securing the flywheel to crankshaft were bent or broken so I bought 4 grade 5 1/2" bolts at tractor supply and cut them to length, cleaned up the end threads and torqued to 85 lbs with blue loctite.

The main hydraulic pump was leaking and worn. I was going to get it repaired at a local shop but I was told that some of the parts would be on backorder until December or later. I bought a aftermarket pump (replacement for # AT 63059) from AMS construction parts. It is made of cast iron and says Geartek on the back. I had the shop fabricate 2 new 1.5 inch hydraulic lines that connect the pump to reservoir tank. Inside the reservoir I found the screen portion of the hydraulic filter detached from nut on the pipe supplying the pump. It was replaced. Lab analysis was done on the hydraulic fluid and determined that it needed changing so the fluid in the reservoir tank was replaced.

Ive used the excavator for about 1 hour and so far so good. Ill post again in 20 to 50 hours.

 

[hosspuller]

GC ... Thanks for up dating your thread. Glad you're up & running again with a home made replacement coupling.

 

[Gerald Chungus]

Ive realized the hour meter sometimes doesnt work but Im sure Ive got over 40 hours on the machine since having it apart. I had to replace a couple hoses in the summer but other than that its still going well.