Parker Majestic 75A Spindle question

Good evening gentlemen. I have a Parker Maj No. 2 SG that the spindle needed to be torn down to replace the front bearings. My question is what causes the denting of the races like the inner bearing race pictured here:


Did improper machinery moving practice cause this? Improper preload? Abusive grinding practices? I am just trying to understand what caused the bearing failure. I recently purchased the grinder without being able to power it up on a friends recommendation. I was very fortunate to find new old stock MM67 CR bearings on eBa$ for a very good price.


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Possibly caused by hammering on wheel adapter.

WRT the bearings, one word: Sopko. Send the spindle to them for rebuilding, it'llcome back good as new. I believe that spindle is seperate, belt driven.

Unnecessary hammering on the spindle may have caused the dents I agree. I have always used Sopko wrenches and wheel pullers to change wheels myself. One of the first things I bought was a new Spoko hub, wheel puller, nut and wrench. There is no telling what the previous owners did to the grinder.

I did call Parker because I was having a hard time removing the spindle from the cube. The tech Zi talked to told me to fashion a puller that used threaded rod threaded into the cube and push the spindle out. I did remove the spindle lock nuts and dust cover to push on the spindle housing so as to not ruin the removed parts. Parker did put me in touch with the company that makes the OEM Parker spindles as well as rebuilds them. To have the 75A spindle rebuilt they quoted between $1800-$2500. The MM67EX CR DU 75# bearings are $705 a pair new so $1410 of the rebuild cost is just the bearings. They recommended using a newer style Parker spindle since the bearings are half the cost of the MM67’s. I haven’t found one yet. I could also use a Haring spindle which they also service but they said the Parker is more robust.

Fortunately I found a set of the needed bearings to replace the front set on eBay which were Fafnir new old stock for $65.00. I purchased the needed Klubber Isoflex grease, thoroughly cleaned the spindle, housing, bearings etc and reassembled the spindle. I found the needed bearing preload torque spec and set accordingly. I have a vfd on the grinder so I started it up at 10% power and slowly brought it up to full speed, carefully monitoring the spindle temp. The spindle never went over 70degrees F.

Unfortunately I will need to replace the rear bearing set now too. The spindle spins freely but does have a bearing whine. The rears are worse than I thought. I will keep a watch for the bearings on eBay, otherwiseI need to save and spend the money on a new pair unless I find a newer spindle at a reasonable price. For now, as long as I am getting a good surface finish I can at least use the grinder.


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