PT425 48" Brush Hog Broken Bolt Removal Tip

MossRoad · Sep 4, 2012

Here's a trick that works well for me to remove a broken brush hog bolt on my PT425 48" brush hog.

I replaced the stock bolts with 2.5" bolts the first time they broke. That leaves about a 1.5" stub inside the hub. I use jam nuts and a wrench to back the broken bolt out from inside the hub.

It takes about 20 minutes if you use air tools and your compressor doesn't toss a belt, break its tensioning device and your kid doesn't spring a last minute 5 mile cross country training run on you that you have to follow on yuur bike. Then it takes 4 hours.

cqaigy2 · Sep 4, 2012

MossRoad said:
Here's a trick that works well for me to remove a broken brush hog bolt on my PT425 48" brush hog.

I replaced the stock bolts with 2.5" bolts the first time they broke. That leaves about a 1.5" stub inside the hub. I use jam nuts and a wrench to back the broken bolt out from inside the hub.

It takes about 20 minutes if you use air tools and your compressor doesn't toss a belt, break its tensioning device and your kid doesn't spring a last minute 5 mile cross country training run on you that you have to follow on yuur bike. Then it takes 4 hours.

Lol, sounds like one of my typical projects. Nice mod.

KMA · Sep 4, 2012

I replaced mine with grade 8 bolts a while back. I also picked up some tire retread off the highway and cut some pieces and added them onto the stop bolts for shock absorption. Hopefully they won't break on me, but I think they protrude slightly into the hub like yours so your trick would come in handy... not sure I would have thought of it myself. Nice job. :thumbsup:

Clumber · Sep 4, 2012

KMA said:
I replaced mine with grade 8 bolts a while back. I also picked up some tire retread off the highway and cut some pieces and added them onto the stop bolts for shock absorption. Hopefully they won't break on me, but I think they protrude slightly into the hub like yours so your trick would come in handy... not sure I would have thought of it myself. Nice job. :thumbsup:

I am assuming that grade 8 bolts have more shear strength? Do you have a photo showing the rubber attached to the bolts? I thought of doing that but I thought the bolt would protrude into the blade path...

Anyway, great ideas guys.

KMA · Sep 4, 2012

Yeah, the grade 8 bolt has more tensile strength and shear strength is a percentage of tensile I believe (not an expert though). Unfortunately I don't have a photo right now of the rubber on the bolts. The retread I happened to pick up was about 3/4 inch thick and had a sort of hexagon pattern that I followed when cutting chunks out. Once mounted, there was approximately a 3/4 inch of material around the stop bolt. I cut them out, drilled holes and added them as if they were washers. I haven't checked them lately to see how they were holding up. I always throttle down before turning on PTO with the brush cutter so the blades don't whip back as hard against the stop bolts.

MossRoad · Sep 4, 2012

This last time I switched to grade 8. We'll see how that goes.

The thread on the 2.5" bolts does not go all the way to the head, which requires the addition of some flat washers. I use three on the bolt, then the blade with bushing, then one more washer between the blade and the bottom of the drum. It ads about a 1/4" to the length that sticks down under the blade. I've been doing this for many years and the washers take a beating. I am finding that if I hit stumps with the blades and back off, nothing bad happens. However, if I progress forward and hit the stump with the bolts, I tend to cause damage to them. Each time I break a bolt, I remove the one that did not break also and inspect it. It is always bent. I wish there was a way to make the blades lower than the bolt heads that hold them on. Gull wing blades, perhaps??? :confused3:

SpringHollow · Sep 5, 2012

I may be way off here but hardened metal is pretty brittle usually. Very strong in tensile strength but I would think a grade 8 bolt will snap when a grade 3 would bend. So, personally, I would not recommend going to grade 8. But maybe I am all wrong.

Ken

woodlandfarms · Sep 6, 2012

I break on average 6 bolts a year. loose 2 blades a year. Want a metal detector but... PT's design to attach blades is truly worthless. I decided to completely go without bumpers, removing the bolts in the spare holes and putting in hex plugs. My neighbor and I have discussed in detail mods to the mower to make the blades less fragile.

Any mod seems to open me up to maybe inbalancing the system. And I have tried every bumper idea there is (From a stack of soft washers to a hockey puck to a tire peice) and none of those work.

For the 1850 taking the mower drive spool out is a PITA. I am perfecting the art of welding a nut to the broken bolt. I have one that refuses to come out. This winter I will pull the spool. I am trying to see if I can put in an acess panel from above to allow me to remove those broken bolts.

I have been running grade 8s for a while. I have no clue if they are any better or worse. I am moving back to 3's just because I don't sense a difference.

SpringHollow · Sep 6, 2012

I broke my first one just a month ago (I only use the bush hog a few times a year right now) and used a metal detector wand used for finding nails in wood to recover my parts. It broke when the head hit a rock and I have not tried removing the bolt yet. I broke one blade a couple of years ago and never found one half. It was near the house - kind of scary.

Ken

MossRoad · Sep 6, 2012

This is the first time I am trying grade 8. I will let you all know how it works out in the future. I will not be brush hogging again, to my knowledge at least, until next spring.

On the subject of locating lost blades/parts... a LONG time ago I bought a toy metal detector from Radio Shack for under $20.00 when I lost some keys in the snow. It found them pretty quickly. Guess what? It works great on large metal objects like brush hog blades buried under an inch of sand, dropped car keys in snow piles, dropped drill bits in grass, etc... Radio Shack does not seem to carry that model any more, but I found these that look very similar to what I have. For under $30.00 it is a fun toy and actually usefull.
If you don't like it, give it to a kid!
Elenco Metal Detector With Beep Alert: Amazon.com: Sports & Outdoors