Both Rear Upper Control Arms Sheared off? WTF!

[comtn4x4]

Update

Ok got the UCA's off last night. The more rear bolts on both were very rusted but but came free without any drama. The forward bolts were easy to remove and had much less rust. I doubt they put a torque wrench on them but I also wouldn't say they were way over torqued. (Spec is 59#) All joint were able to be removed by hand without any tools and had reasonably good movement. I doubt they weren't greased at all, however they weren't greased how I would have done it. (As was said earlier if they weren't greased they woulda squeaked like crazy.)In their defense the packet of grease that came with them was relatively small. Let's remember these were on for 3 years, this wasn't an install the bushings and instant snap scenario.
From the looks of the snapped area of the arms it appears one snapped then the other gave at a later time. The arms themselves do not appear to have been in contact with anything causing them to snap. I'm not experienced with welds so I'll let someone else analyze that but the ends of both appear pretty flat to me, so maybe the weld gave? I think the idea that the installer over heated the arms removing the old bushings is at least a strong contributing factor if not the sole reason.

I attached pictures as well

 

[comtn4x4]

If anyone knows the part number for the bolts I would appreciate the help. The forward bolts are different than the rear bolts. When I look in the Toyota parts catalog this doesn't seem to be the case. It's possible the installer swapped out the bolts.


The only bolt part number I can find is 90119-14040
The nut I think is 90178-A0058


EDIT:
I think I need the following parts:
90119-14040 2each for mount to axle
90105-12340 2 each for mount to frame

90178-A0058 not sure about this, definitely 2 of these maybe


Thanks in advance

 

[rdruss]

Yes, the bolts are definitely not threaded all the way to the head, the other bolts are correct.

 

[comtn4x4]

Yes, the bolts are definitely not threaded all the way to the head, the other bolts are correct.

Thanks, yeah I was thinking they might've cut the old ones off

 

[honda250xtitan]

this reaffirms my comment....buy one aftermarket upper with upgraded heims. and see how it feels. you wont have to worry about contacting the fuel tank at full droop

since it looks like one broke a while before the other one.

i DO NOT recommend buying from PRG as his customer service is absolutely atrocious BUT, he knows suspension.
FJ/4 RunnerGX470 4-Link KitThis is our 4-link Fj and 4 Runner rear link kit. This kit elliminates the driver's side upper link and is 100% direct bolt-on. No need to drill out holes or run custom bolts. Because our bearings do not have slop like rubber or urethane, there is no binding at all through the full range of movement. Zero side deflection, zero axle wrap and 100% free movement vertiacally and through full articulation. Becasue we use no urethane, there are no squeaks either and no messy zerk fittings. The lower links are 1.75" dia x .120 wall DOM (.250 wall on request and for more $$), the upper link is 1"x .250 wall and the panhard is 1.25" x .250 wall. The upper and panhard bar use left and right hand threads to make adjustments super easy, but we do send these out adjusted to the stock dimensions so you can simply bolt them on and be on your way. The lower links use FK 1" teflon-lined uniballs and FK 1x1.25" 3-pc teflon-lined heims in right hand thread (all of the bearings (heims) we use are NOT the shitty 2-pc Chinese heims that most offroad shops use. If someone says Heims are noisey, they use garbage bearings...GOOD heims are quiet). The upper link and panhard use FK 3/4 3-pc telon-lined heims. All the bearings are readily availble through many vendors, as well as us, should you need replacement parts in the future.Tubes are shown in RED but can also be plated in BLACK. Typical build time is about 10-15 working days. Why a 3 link and panhard vs 4 link and panhard...simple...it works better. The factory uses soft rubber bushings and a sway bar, there is a certain amount of "bind" built in to the OEM geometry...those bushings are also really cheap. Switching to this style of geometry has ZERO bind in the full usable range of movement and this allows for less stress on all the chassis mounting points as well as more life from the bearings. It simply costs more to do this. And any aftermarket 4-link w pahard bar kit that uses bearings at any pivot point is hurting the chassis and decresing flex and ride quality. | PRGProducts.Com
for the lazies who wont click a link .....


""Why a 3 link and panhard vs 4 link and panhard...simple...it works better. The factory uses soft rubber bushings and a sway bar, there is a certain amount of "bind" built in to the OEM geometry...those bushings are also really cheap. Switching to this style of geometry has ZERO bind in the full usable range of movement and this allows for less stress on all the chassis mounting points as well as more life from the bearings. It simply costs more to do this. And any aftermarket 4-link w pahard bar kit that uses bearings at any pivot point is hurting the chassis and decresing flex and ride quality.""

edit: wow that URL is weird

 

[Argyle Edison]

I didn't read all the replies, so I apologize if it was already stated


Did you happen to tighten the suspension bolts when the vehicle was still in the air ?


The bushing material will bind badly and cause some pretty crazy results at times. Not saying this is what happened to you, but I could see it putting a serious bind on parts. (I have seen it)

 

[comtn4x4]

I didn't read all the replies, so I apologize if it was already stated


Did you happen to tighten the suspension bolts when the vehicle was still in the air ?


The bushing material will bind badly and cause some pretty crazy results at times. Not saying this is what happened to you, but I could see it putting a serious bind on parts. (I have seen it)

I haven't got the new bars installed yet as I'm picking up new hardware tomorrow morning.

 

[Jeremy556]

I didn't read all the replies, so I apologize if it was already stated

Did you happen to tighten the suspension bolts when the vehicle was still in the air ?

The bushing material will bind badly and cause some pretty crazy results at times. Not saying this is what happened to you, but I could see it putting a serious bind on parts. (I have seen it)

Not an issue with the aftermarket poly bushings he has/had, as the inner sleeve is not connected to the outer and can rotate freely besides the drag of the poly bushing. Factory style bonded rubber bushings should absolutely be secured at ride height to avoid undue stress and tearing.

Any chance we can get some high res, well lit, images of the shear area of the UCAs once they are replaced?

Pretty sure I'm running the same bushings in my rear control arms, but only have about 15k miles under relatively mild conditions for my normal use. As mentioned previously in this thread, they obviously don't provide the same torsional flex of the stock rubber bushings, which would likely end up in the failure mode you have experienced

 

[comtn4x4]

Any chance we can get some high res, well lit, images of the shear area of the UCAs once they are replaced?

Jeremy, I'm happy to take more pics. Did you see the ones on the previous page? If so give me an idea what more you're looking for.

 

[comtn4x4]

[MENTION=78273]Jeremy556[/MENTION]




How's this look:

 

[comtn4x4]

The new joints are narrower than stock, I assume I'll be needing some washers to take up the gap? I can't imagine not having them in there

 

[Jeremy556]

[MENTION=78273]Jeremy556[/MENTION]
How's this look:

Awesome, thanks. Hopefully some people that are knowledgeable might be able to shed some insight on the failure by looking at the break. It looks like one broke a while before the other with more rust on the broken area.

 

[Jetboy]

FWIW - It's very likely the result of the bushings. Poly bushings are not an upgrade in many cases and are not appropriate for the rear control arms. The rear control arms require more complex motion than a simple hinge joint like the front suspension. The ends need to both hinge around the center bolt but also twist axially as the link rotates and flex out of alignment as them move through the various suspension motions.

The flex out of alignment with the bushing pivot bolt is probably what caused this failure. Because the bushing wouldn't flex enough to accommodate the angles needed, the solid rod was bending at the top of the weld bead. That's where the load would be maximum and there's a stress riser. So most likely that's where you started to get metal fatigue after repeated bends, just like breaking a paperclip. And eventually it failed.

Fortunately it sounds like it wasn't on the highway in an emergency maneuver or something like that.

Looks like you have some replacements. I would put some washers in or you may be able to collapse the brackets enough to tighten up. I would not let them float loose on the collar of the through bolt.


Good luck.

You can see some of the classic metal fatigue in those ends, although it's hard without a bit more resolution than you end up with over the forum. There are pretty clear progression zones and then an area of fracture when it broke completely.

I think an engineer would call this a "high cycle low stress fatigue fracture". But I'm not an engineer. So I call it a paperclip break. The main takeaway is that it wasn't from hitting something hard. It was from lots of small back and forth bending over time where the poly bushing wouldn't flex enough and resulted in the shaft bending back and forth.

If it were a result of an instant impact where it pulled so hard on the end that it ripped apart it would look more like this (ductile fracture):

 

[comtn4x4]

FWIW - It's very likely the result of the bushings. Poly bushings are not an upgrade in many cases and are not appropriate for the rear control arms. The rear control arms require more complex motion than a simple hinge joint like the front suspension. The ends need to both hinge around the center bolt but also twist axially as the link rotates and flex out of alignment as them move through the various suspension motions.


Jetboy, as always thank you for your thorough reply! That makes sense and I'm not arguing at all. But.... if the bushings are the issue and these bushing seem to be a relatively common "upgrade" to the rear suspension. Why is this the only instance I've seen of the upper rear control arms failing?
My bad luck? (That actually makes sense, I am a walking perfect storm) I've run them longer than others? Maybe. (I looked it up I installed them almost exactly 3 years ago, November 2019. about 40,000 miles) It seems really odd to me

 

[comtn4x4]

New Arm Installed!

I got the arm installed today. Yes that's right [MENTION=137195]honda250xtitan[/MENTION] you got your wish. Only the passenger side arm installed. However, that wasn't my intent initially. My local Toyota dealer only got me one set of hardware so I could only do one, and I need the truck. I may install the second one later. I did install 2 washers on each joint to take up the slop. Took a test drive and she's running great! Thanks to everyone especially [MENTION=98153]MStudt[/MENTION] for getting these to me on the fly.

Mike these are really well made and really competitive in price. I'd recommend them to anyone who's interested. I'll report back as time goes on regarding performance and maintenance.

 

[MStudt]

Mike these are really well made and really competitive in price. I'd recommend them to anyone who's interested. I'll report back as time goes on regarding performance and maintenance.

Thank you for the business! I'll have to look into why these are narrower than yours since they match the width on my 2019.

Mike

 

[Jetboy]

FWIW - It's very likely the result of the bushings. Poly bushings are not an upgrade in many cases and are not appropriate for the rear control arms. The rear control arms require more complex motion than a simple hinge joint like the front suspension. The ends need to both hinge around the center bolt but also twist axially as the link rotates and flex out of alignment as them move through the various suspension motions.


Jetboy, as always thank you for your thorough reply! That makes sense and I'm not arguing at all. But.... if the bushings are the issue and these bushing seem to be a relatively common "upgrade" to the rear suspension. Why is this the only instance I've seen of the upper rear control arms failing?
My bad luck? (That actually makes sense, I am a walking perfect storm) I've run them longer than others? Maybe. (I looked it up I installed them almost exactly 3 years ago, November 2019. about 40,000 miles) It seems really odd to me

I think most people who put them in don't cycle the suspension very far or very often. If you have extended travel rear shocks, that would also add to it. Most of the damage will occur when the suspension is fully articulated. You can probably go lots of highway miles and never have an issue. It just boils down to number of cycles and the amount of deflection. So... take it easy, spend more time on the highways. And you'll be good to go!

 

[seatia]

The new joints are narrower than stock, I assume I'll be needing some washers to take up the gap? I can't imagine not having them in there

You are 100% correct.
The inner shaft of the heim should be torqued solid to the mounts, so use whatever (washers, tubing) to make a snug fit and then torque the thru bolt properly. The inner should not move at all.

 

[comtn4x4]

I think most people who put them in don't cycle the suspension very far or very often. If you have extended travel rear shocks, that would also add to it. Most of the damage will occur when the suspension is fully articulated. You can probably go lots of highway miles and never have an issue. It just boils down to number of cycles and the amount of deflection. So... take it easy, spend more time on the highways. And you'll be good to go!

Yes I do have extended travel shocks.

Lol, more highway? Nah just more trips to the mall.

 

[honda250xtitan]

lol. so hows it feel with just one? i've considered going this route even though i feel like the rear end works pretty well with all stock joints and toytec springs/king shocks/bumps/kdss switched off.