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MTD 990 Transaxle Dissassembly


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#1 VTXrider ONLINE  

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Posted March 13, 2016 - 12:01 PM

My 73' parts machine trans-axle is going to be put to use. My most resent restore had a leaky rear axle seal and is leaking again. Removed the seal for inspection and found the axle is damaged. A PO used a tool to remove the seal and left gouges in the shaft so it has to be replaced.

 

Never had one of these apart before so I proceeded with a rather messy disassembly. The axles are held in the differential with clips so I think I will just replace the differential assembly. It slides out of the housing easily.

 

Hard part is going to be the removal of the trans-axle in the tractor........

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#2 mrmr56 OFFLINE  

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Posted March 13, 2016 - 12:18 PM

Looking at all of the needle bearings in that peerless transmission, I can see why the MTD 990 runs so quiet. It would take a lot of abuse to tear one up. Thanks for the breakdown pics. That is much better than a pdf parts diagram.


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#3 glgrumpy ONLINE  

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Posted March 13, 2016 - 01:49 PM

Your braver than I would be going in there. Worse would be going into the hydro-drive motor I would think. Lots of little pieces in those and have no idea what to look for as bad on that. Big scare for me would be the gaskets or silicone seals to put back together and NOT have leak there then. You gonna cut gaskets, leave these, or silicone?  I think I would  have to use orig gasket if still stuck on half good and just use shellac on the other side of it. I hate silicone, the mess and the look.


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#4 ducky OFFLINE  

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Posted March 13, 2016 - 04:54 PM

For sealant I would use an anaerobic like Locktite 518 so you don't plug things up with cured sealant that would squeeze inside the seam and break loose.  Not good for a hydro unit.


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#5 VTXrider ONLINE  

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Posted March 13, 2016 - 07:13 PM

This trans-axle will not be going back together. The case has an epoxy patch over a hole in the bottom and one axle housing is damaged with a broken hitch ear. The hydro transmission and charge pump may be good, I never had the tractor running.

 

Hoping the transmission I remove comes apart as easily as this one. Thank for the tip Ducky about the Loctite 518.

 

I have used the Blue ATV silicone on many gaskets with no problems. I use a very thin transparent layer. More is not better when it comes to gasket sealer. The gasket on this transmission came off in one piece so I have a spare.


Edited by VTXrider, March 13, 2016 - 07:15 PM.

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#6 boyscout862 ONLINE  

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Posted March 13, 2016 - 07:18 PM

Isn't there a good manual for the transaxle in the Manuals Section? A slightly scratched axle can often be saved by smoothing with a hand sharpening stone. Good Luck, Rick
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#7 VTXrider ONLINE  

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Posted March 13, 2016 - 07:43 PM

Isn't there a good manual for the transaxle in the Manuals Section? A slightly scratched axle can often be saved by smoothing with a hand sharpening stone. Good Luck, Rick

I will take a picture of the axle damage. I should have noticed it when I replaced the seal but only wiped it clean and installed it. It is not a slight scratch but a gouge, like with a chisel.


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#8 firefight100 OFFLINE  

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Posted March 13, 2016 - 08:00 PM

You wouldn't have to replace the axle because of a gouge.  You can use a seal repair sleeve.  Available from most bering houses.  Timken, Parker and several others make them  Here is one excample 

http://www.parker.co...R SLEEVES&Wtky=

I also included the manual for the hydraulic pump and the transmission.

Cheers.

 

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#9 VTXrider ONLINE  

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Posted March 14, 2016 - 07:37 AM

You wouldn't have to replace the axle because of a gouge.  You can use a seal repair sleeve.  Available from most bering houses.  Timken, Parker and several others make them  Here is one excample 

http://www.parker.co...R SLEEVES&Wtky=

I also included the manual for the hydraulic pump and the transmission.

Cheers.

Thanks for the tip FF. Is the repair flange cemented to the shaft with some bearing adhesive? How would I drive the repair flange the length of the axle to the seal area?

Thank you for posting the manuals. I have the Eaton already but the Peerless will go into the archives.


Edited by VTXrider, March 14, 2016 - 08:09 AM.


#10 VTXrider ONLINE  

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Posted March 15, 2016 - 07:30 AM

Possibly if the sleeve is heated, it will expand enough to slide it over the damaged section. I might give this a try.

 

A problem with using the repair sleeve is in the future it will be difficult to remove the axle from the case. The axle bearings need to slide off the shaft and the sleeve will prevent that. Getting the sleeve off would be nearly impossible without damaging the shaft.



#11 Sawdust OFFLINE  

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Posted March 15, 2016 - 09:44 AM

I used the Speedi sleeve from SK using Loctite 620 to seal the sleeve to the shaft as recommended on my output shaft for my MF12. I had the same leaking problem because the PO nicked the shaft trying to put a seal on. The process went very well.  I did try cleaning the shaft with various abrasives but didn't work. I haven't re assembled the unit yet to give you any follow ups. It would prevent you from removing the axle bearings later.

 

 http://gardentractor...ebirthed/page-7


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#12 VTXrider ONLINE  

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Posted March 15, 2016 - 02:45 PM

I used the Speedi sleeve from SK using Loctite 620 to seal the sleeve to the shaft as recommended on my output shaft for my MF12. I had the same leaking problem because the PO nicked the shaft trying to put a seal on. The process went very well.  I did try cleaning the shaft with various abrasives but didn't work. I haven't re assembled the unit yet to give you any follow ups. It would prevent you from removing the axle bearings later.

 

 http://gardentractor...ebirthed/page-7

The Locktite 609 is heat release-able but lower temperature rating. 150 deg C compared to 232 deg C. I have both and may try the 609.


Edited by VTXrider, March 15, 2016 - 02:45 PM.


#13 VTXrider ONLINE  

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Posted March 15, 2016 - 04:57 PM

Ordered a sleeve from here

http://intechbearing...iant=1069918541

 

and a couple more axle seals from Outdoor Distributors.


Edited by VTXrider, March 15, 2016 - 04:58 PM.

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#14 VTXrider ONLINE  

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Posted March 17, 2016 - 11:33 AM

The shaft is prepared for installation of the repair sleeve. My fingers are crossed.

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#15 VTXrider ONLINE  

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Posted March 21, 2016 - 02:39 PM

Received the repair sleeve today and installed it. I had to find a way to drive it onto the shaft. Ended up using a 1" black pipe coupler and a piece of 1-1/4" conduit pipe against the coupler. Hardest part is to know when to stop in the right spot because it is quite narrow. (I forgot to mark the outside edge of the seal before I removed it :( ). It cost my spare seal because it was not on far enough. I used green Loctite 609 bearing adhesive. About 1/32" of the sleeve is sicking out from the seal.


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