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Blades too Tight

#1

B

bigge31566

I have a 72" Bunton and every time I change the blades the impact will not remove the bolts, I have to get a pull bar and cheater even after using anti seize, and trying to hold blades way too much, I put them on with impact, is there any different washer or something I can do to prevent this


#2

MBDiagMan

MBDiagMan

What kind of impact are you using? I've used an ingersoll 1/2" impact with 10si shop air for many years with no issues. It sounds like you need some more oomph on your impact when taking them off.

Larry


#3

M

motoman

There have been previous threads on blade bolt grading, lubing , torque , torque reduction after lube, and impact wrenches. Try searching keywords in this forum.


#4

B

bigge31566

I'm using a 1/2" IR with 90 psi


#5

djdicetn

djdicetn

bigge31566 said:
I'm using a 1/2" IR with 90 psi
Click to expand...

I just installed a mulch kit on my Gravely and the instructions stated to torque the bolts to 115-120ft/lbs when installing the mulch blades. I had to "wedge the OEM blades with channel-locks and a piece of plywood" underneath the deck to break the bolts loose and remove them. Seems to me that that torque setting is abit excessive if my automobiles recommend 100-110ft/lbs. Why would blades need to be torqued higher that wheels on a car?????


#6

MBDiagMan

MBDiagMan

Your car has multiple lug bolts/nuts that are not subject to rotation that requires a friction fit. A 1/2" break over bar and the correct size socket will apply that much torque without too much trouble.

Larry


#7

M

motoman

This forum has provided a "from scratch" or backup reference for bolt , torque, thread lube considerations. Suggest it be used after trying to get the manufacturer's values. Air wrenches can help, but are destructive if misused. Use the search function.


#8

B

bigge31566

Thanks for all the info, I think I will start to tighten with ratchet and loosen with impact to see if it makes a difference


#9

A

andy135

On most impact guns the loosen torque is always bigger than the highest setting tighten torque. I started from lightest setting then check with torque wrench. Now I know the second highest setting is good enough.


#10

Lawnboy18

Lawnboy18

djdicetn said:
I just installed a mulch kit on my Gravely and the instructions stated to torque the bolts to 115-120ft/lbs when installing the mulch blades. I had to "wedge the OEM blades with channel-locks and a piece of plywood" underneath the deck to break the bolts loose and remove them. Seems to me that that torque setting is abit excessive if my automobiles recommend 100-110ft/lbs. Why would blades need to be torqued higher that wheels on a car?????
Click to expand...

That is a lot! I just tighten mine until they are more than snug kinda. Well, until I cannot turn them anymore. Works for me! 120 is almost as much as bolting a car head!!!:confused2:


#11

B

Brucebotti

You definitely don't want that blade coming off at 18,000fps....:thumbdown:
Bruce


#12

M

motoman

Seat of pants really should not be used for fastener torque. Spend the time to select correct torque and look at the fasteners that might have been overstretched. Over tightening and work hardened/necked fastener will break and ... yes, 1800 fps loose blades not good. :smile:


#13

MBDiagMan

MBDiagMan

I can't argue with any of this, but you need to keep in mind that due to the direction of rotation, the bolts tend to tighten themselves anyway.

In about 55 years of mowing, I can never remember a blade coming loose. Either I am an excellent blade tightener (I've never been rated exellent at anything) or the blades have kept themselves tight.

Larry


#14

reynoldston

reynoldston

MBDiagMan said:
I can't argue with any of this, but you need to keep in mind that due to the direction of rotation, the bolts tend to tighten themselves anyway.

In about 55 years of mowing, I can never remember a blade coming loose. Either I am an excellent blade tightener (I've never been rated exellent at anything) or the blades have kept themselves tight.

Larry
Click to expand...

I got to agree with this. As for myself I use a torque wrench. I make sure the threads are clean and use light oil on them. If you are over torqueing the bolts you are making them weaker every time you are doing so. You can't properly torque a bolt with a impact wrench I don't care how good you think you are with one.


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