Toro MX4250 spindle maintenance
The Toro MX4250 is a ZT ride on mower (riding mower).
I previously reported that after 200h, the original spindle bearings were in very poor condition, about 3mm of play at the blade ends, and they were replaced. There are lots of Chinese parts on this “made in the US made” mower, so the bearings might well have been Chinese in origin.
The original spindles are not greaseable, and were fitted with 6203RS (rubber seals on both sides) ball bearings.
There is lots of stuff online about mower spindles, they are a significant maintenance problem.
A grab bag of online expert advice:
- No need for greasing, the bearings are sealed for life (that might be less than 100h).
- Modify residential spindles by adding a grease nipple like commercial mowers use.
- RS bearings cannot be greased, the seal will pop out.
- Punch the bearings out, remove the inner seals and put them back.
- Fit a grease nipple and remove the rubber seal from the inside of both bearings.
- Some commercial mowers are fitted with a grease nipple and metal shielded (ZZ) bearings.
Since these spindles hold a lot of grease, I intend greasing with a pneumatic greaser, and they tend to inject very quickly and the risk of an RS seal popping should be mitigated.
Above is a 6203ZZ (metal shielded) bearing. There is a gap of about 0.5+mm between bearing inner and the shield, shields are on both sides.
So, the path I have chosen to implement experimentally is to:
- drill and tap the spindles and fit M6 grease nipples;
- replace the bearings with 6203ZZ (metal shielded); and
- grease the spindle at deck clean services (twice a year when blade type is changed, sharpened and balanced).
This work was done with the spindles fixed in the deck. The spindle bolts are renowned for seizing or shearing, and removal is probably best avoided.
The bearings can be punched out fairly easily, just display the spacer bush so that the punch can get purchase on the bearing inner. I always discard bearing that have had large force applied between inner and outer.
Above is a view of the spindle with grease nipple. The bearing at the blade end is recessed about 5mm into the housing, and the end of the shaft has a flange that fits into that recess, somewhat protecting the bearing from dirt and water.
Nevertheless, it would be imprudent to direct a high pressure washer directly at that area. That doesn’t prevent cleaning the outer area of the deck underside where grass accumulates.
Above is a view of the top of the spindle housing and the underside of the drive pulley. The bearing fits almost flush with the top of the housing, it would be imprudent to direct a high pressure washer directly at that area.
On this mower, the pully has a solid centre disc, no cutouts to make observing the greasing operation… but also no cutouts to let water jets into that area. An inspection mirror makes the job easy.
Time will tell whether the planned maintenance regime is practical and what bearing life is experienced.
What I chose to not do is simply buy a set of Chinese replacement spindles with grease nipples from eBay or Aliexpress… as I would still need to have replaced the bearings.