fj80 RADIUS ARMS

[lelandEOD]

Ticking time bomb, fellas.

This happened to me and @BadReligion on Rubicon last summer.

 

[Box Rocket]

Ticking time bomb, fellas.

This happened to me and @BadReligion on Rubicon last summer.
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I can tell from the pics that those arms were basically notched to clear the tie rod, removing the upper "T" of the arm. That's definitely going to weaken the arms significantly! It's not necessary to remove that much from the arm and as long as you're not removing any complete portion of the upper "T" it's not going to weaken the arms enough to be a risk.

 

[Box Rocket]

Typically you don't need to take much more than the center ridge off the arms to have enough clearance for the tie rod. You can see on my radius arm that's really all that was removed. This isn't going to weaken the arms at all and is usually all that is needed. Even if you have to take a bit more off, as long as you're not grinding/cutting through the top flat portion of the arm there is very little risk of failure. Cutting a giant notch out of the arms like the above pics will no doubt make the arms a "ticking time bomb". Chalk it up to user error.

Untitled by Adam Tolman, on Flickr

 

[leonard_nemoy]

Ticking time bomb, fellas.

This happened to me and @BadReligion on Rubicon last summer.
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Oh snap!!! Literally. I bet that was a fun day.

Like @Box Rocket mentioned, it looks like those arms were seriously notched or maybe they broke that way.....

Either way I would still clearance mine again in the same manner as box rocket detailed in his photos. Just removing that little ridge along the top shouldn't hurt a thing.

 

[mudgudgeon]

solid steel, again very heavy only concern is unsprung wieght and now the arms are so strong something else might break i.e. mounts in an impact.
I am out on the boat this weekend, when I get home will take some pics. not to exciting but here is a pic I saw online with the arms not my truck.

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Made with Bisalloy 80. I pretty sure it exceeds the strength of 4140. Used for fabrication in high stress, high fatigue applications

Superior are stand up guys, and build some innovative stuff, and have been in the industry for a long time.

 

[mudgudgeon]

Ticking time bomb, fellas.

This happened to me and @BadReligion on Rubicon last summer.
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Yeah, there's a difference between smoothly grinding for a few millimetres of clearance, and hacking a fücking big hunk out of your arm.

 

[Broski]

Ticking time bomb, fellas.

This happened to me and @BadReligion on Rubicon last summer.
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The arms are cast into a I beam, If you remove the upper flange of the I beam you definitely have a ticking time bomb

I hope you replaced both of those arms.

Nice trail fix by the way!

 

[lelandEOD]

It got us home! And yes, the amount of material he removed from the radius arms definitely led to the failure and he has since replaced them with Delta VS arms. I don't think I saved the close up but if you look closely at the corrosion visible in the first photo, you can tell that a stress crack formed some time ago but it took one good hit to snap the arm in two. Also, the grain structure of the steel really led all of us to conclude the factory arms are cast, not forged. The trail welder @dirtydave agreed and used a fairly ductile filler rod for the scab repair.

I'm not going to debate the how much is ok to remove but rather wanted to raise awareness since many people read topics like these and end up doing something to get themselves in trouble. YMMV.

 

[Broski]

There no debate. those arms were hacked.

Whenever something is modified a little common sense is required.

 

[Box Rocket]

It got us home! And yes, the amount of material he removed from the radius arms definitely led to the failure and he has since replaced them with Delta VS arms. I don't think I saved the close up but if you look closely at the corrosion visible in the first photo, you can tell that a stress crack formed some time ago but it took one good hit to snap the arm in two. Also, the grain structure of the steel really led all of us to conclude the factory arms are cast, not forged. The trail welder @dirtydave agreed and used a fairly ductile filler rod for the scab repair.

I'm not going to debate the how much is ok to remove but rather wanted to raise awareness since many people read topics like these and end up doing something to get themselves in trouble. YMMV.

It was definitely a good trail fix for a bad situation. That's a rough trail failure and would leave a lot of people stranded. Nice that you had someone in the group with a trail welder.

not meant to be argumentative but I have it from a reliable source at Toyota that the factory arms are in fact forged, not cast.

 

[PIP]

Also, the grain structure of the steel really led all of us to conclude the factory arms are cast, not forged.

The arms are forged, not cast. The grain structure doesn't tell you anything one way or the other. The grain structure tells about the material composition, not how it got to be the shape it is.

The very large parting line and lack of any runners leaves absolutely nothing to debate- These arms are forged.

 

[graham5david]

Just get some MAF drop brackets

 

[Box Rocket]

Just get some MAF drop brackets

The eimkeith brackets are a nicer design than the MAF ones IMO (if someone were to choose this direction).

 

[Broski]

The eimkeith brackets are a nicer design than the MAF ones IMO (if someone were to choose this direction).

In less your going to be hard rock crawling, @eimkeith drop brackets are one of the best way to correct caster and make room for 37s on a small lift.

Not sure why they are not more popular!!

 

[BadReligion]

There no debate. those arms were hacked.

Whenever something is modified a little common sense is required.

I'll be the first to admit it was user error, but sorry for not being a metallurgy expert. I'd argue that my common sense is better than most, but apparently not yours. I clearanced them on the vehicle before a trip and cycled the suspension a few times to make sure the oversized tie rod was not hitting. In hindsight, I probably could have removed a bit less material and not left a sharp notch perpendicular to the top of the arm, which created a stress riser. Now I know. There isn't exactly a "how to" guide on this. They lasted 10 years and multiple trips on the Rubicon, Dusy Ershim, and Moab before failing when 6500lbs of 80 series came down hard on that single arm. Multiple contingencies were in place to get the truck moving again, but in this situation "plan A" worked well.

Lesson learned, fixed likely for good with the Delta Arms. Anything other than castor correcting radius arms on a larger lift and big tires is less than ideal.

 

[graham5david]

In less your going to be hard rock crawling, @eimkeith drop brackets are one of the best way to correct caster and make room for 37s on a small lift.

Not sure why they are not more popular!!

The MAF brackets are beefy. And for the price much easier to install than caster plates. Plus you don't have to hack up the radius arm mounts on the axle. Iron man makes some now as well. I wasted a lot of time trying to fix caster until I bought the brackets. Never had a problem and never got hung up on anything.

 

[leonard_nemoy]

I'll be the first to admit it was user error, but sorry for not being a metallurgy expert. I'd argue that my common sense is better than most, but apparently not yours. I clearanced them on the vehicle before a trip and cycled the suspension a few times to make sure the oversized tie rod was not hitting. In hindsight, I probably could have removed a bit less material and not left a sharp notch perpendicular to the top of the arm, which created a stress riser. Now I know. There isn't exactly a "how to" guide on this. They lasted 10 years and multiple trips on the Rubicon, Dusy Ershim, and Moab before failing when 6500lbs of 80 series came down hard on that single arm. Multiple contingencies were in place to get the truck moving again, but in this situation "plan A" worked well.

Lesson learned, fixed likely for good with the Delta Arms. Anything other than castor correcting radius arms on a larger lift and big tires is less than ideal.

That's a trip you will never forget. Reminds me of the time my wheel came off lol. Thats my profile picture.

 

[leonard_nemoy]

The MAF brackets are beefy. And for the price much easier to install than caster plates. Plus you don't have to hack up the radius arm mounts on the axle. Iron man makes some now as well. I wasted a lot of time trying to fix caster until I bought the brackets. Never had a problem and never got hung up on anything.

@eimkeith makes weld in drop brackets. They do the same thing as the man a fre and Ironman brackets but they are a little more low profile and won't hang up on the rocks as bad as the man a fre and Ironman brackets. His RAM drop mounts are definitely the way to go for caster correction.

 

[BadReligion]

That's a trip you will never forget. Reminds me of the time my wheel came off lol. Thats my profile picture.

I'm guessing that a pic of a brake caliper (minus tire) buried in dirt/sand resulted in a series of memorable events.

We lucked out in a number of ways. It did not happen on the road (which could have been bad), but instead at the end of the day and 100 yds from camp at Buck Island, on a bypass that did not block the main trail, with a very skilled welder in camp too. I had a sat phone so I was able to call in a spare radius arm that was going to arrive the next day since the field repair was an unknown, but it held the entire time. Carrying a few sections of 1/2" flat bar stock also worked out in my favor as that helped reinforce the repair.

An alternator powered welder or battery GoWelder is definitely something nice to have on the trail if you are in a large group. We have used both on multiple occasions.

 

[leonard_nemoy]

I'm guessing that a pic of a brake caliper (minus tire) buried in dirt/sand

Absolutely lol, the hub left a 100 yard trench in the dirt road. I was doing about 60 mph when it happened. Driving 50 miles home with 3 wheel studs was almost as scary as the wheel coming off.