Tightening blades on LX178 44" deck

Shimon · Feb 24, 2008

Not sure if I should post here or in Lawn & Garden...mods move post if necessary.

Bought an LX178 (94 model) with the 44" mulching deck. I'm cleaning up the deck and sharpening the blades. When I first got the mower deck turned over (three spindles with two blades each for total of 6 blades) I found the two outer sets of blades would spin independently of the pulleys which told me they weren't torqued down all the way. The center set of blades spun together with the pulley.

Now I'm putting it all back together and the manual says to torque everything down to 55 ft-lbs. I'm trying to tighten the bolts but need a way to keep the pulleys from spinning. Is it ok to stick a screwdriver through one of the four openings in the pulley and hold the pulley against the aluminum spindle housing? I just don't want to break anything. Is there a better way to keep the pulleys stationary so I can torque the bolts to 55 ft-lbs?

Enclosed is a photo of the top of the deck from the manual. The openings in the pulleys can be seen in the top most pulley (the other two pulleys are under the side covers). The other photo is from the operators manual.

4720 OWNER · Feb 25, 2008

I 4 toro, 72" cutter deck. I took a 2x4, cut a slot in it lengthwise so could just slide it on the blade and wedge it between the blade and the deck. The slot just holds the 2x4 up so do not have to hold it by hand until get some torque on it. Mine are backward threaded. Just torque away then, at least for me.

Shimon · Feb 25, 2008

I can't use the block of wood method because the problem is that as I tighten the bolt, it just spins along with the pulley through the spindle. I can't get enough friction between the blades and then washer under the bolt to keep everything from spinning. When I tighten the bolt as much as can, I can still spin the blades independently of the bolt/washer/spindle/pulley.

4720 OWNER · Feb 25, 2008

Maybe is works for me since the deck in on the mower. Lock washer between the blade and the pulley? Just have a real aversion to putting things around jammed around aluminium. For me it just tends to end up cracking unexpectedly or worse.

SPYDERLK · Feb 25, 2008

Shimon said:
Not sure if I should post here or in Lawn & Garden...mods move post if necessary.

Bought an LX178 (94 model) with the 44" mulching deck. I'm cleaning up the deck and sharpening the blades. When I first got the mower deck turned over (three spindles with two blades each for total of 6 blades) I found the two outer sets of blades would spin independently of the pulleys which told me they weren't torqued down all the way. The center set of blades spun together with the pulley.

Now I'm putting it all back together and the manual says to torque everything down to 55 ft-lbs. I'm trying to tighten the bolts but need a way to keep the pulleys from spinning. Is it ok to stick a screwdriver through one of the four openings in the pulley and hold the pulley against the aluminum spindle housing? I just don't want to break anything. Is there a better way to keep the pulleys stationary so I can torque the bolts to 55 ft-lbs?

Enclosed is a photo of the top of the deck from the manual. The openings in the pulleys can be seen in the top most pulley (the other two pulleys are under the side covers). The other photo is from the operators manual.

Assuming the bolts are at least 7/16", tighten it as well as you can by hand and then give it a couple quick [1/4 sec] bursts with a 1/2" impact.
larry

Shimon · Mar 1, 2008

I used my impact to tighten the bolts and that worked great but when I used my torque wrench to do the final tightening to 55ftlbs, I found that even though the bolts were at least 55 ftlbs the blades could still be moved independently of the pulley (not by hand but with the blades blocked with wood against the deck and using the torque wrench on the bolt). It's almost as if the the washer under the bolt isn't thick enough to apply enough pressure on the blades to keep them from spinning. Is this normal? Maybe so if you hit something the blades will give a little without the transmitting all the shock to the spindle/pulley? Or should I put a second washer in there as a shim to make sure the bolt applies enough pressure to sandwich the blades in place?

SPYDERLK · Mar 1, 2008

Shimon said:
I used my impact to tighten the bolts and that worked great but when I used my torque wrench to do the final tightening to 55ftlbs, I found that even though the bolts were at least 55 ftlbs the blades could still be moved independently of the pulley (not by hand but with the blades blocked with wood against the deck and using the torque wrench on the bolt). [[[It's almost as if the the washer under the bolt isn't thick enough to apply enough pressure on the blades to keep them from spinning. Is this normal?]]] Maybe so if you hit something the blades will give a little without the transmitting all the shock to the spindle/pulley? Or should I put a second washer in there as a shim to make sure the bolt applies enough pressure to sandwich the blades in place?

Theres something wrong - worn as you surmise, or missing parts. See if you can get a look at some new parts then correct yours accordingly.
larry

Shimon · Mar 1, 2008

I think I'll do that. There isn't much to it. The deflector (#15 in the diagram) sits between the blades and the spindle and then there is the washer (#24) and bolt. I guess the deflector and/or washers could be worn enough to make a difference but they look to be ok.

SPYDERLK · Mar 2, 2008

Shimon said:
I think I'll do that. There isn't much to it. The deflector (#15 in the diagram) sits between the blades and the spindle and then there is the washer (#24) and bolt. I guess the deflector and/or washers could be worn enough to make a difference but they look to be ok.

Does the bolt screw freely into the shaft far enuf to clamp everything up? You could be running into grody threads at the bottom of the hole.
larry