Both Rear Upper Control Arms Sheared off? WTF! - Page 5 - Toyota 4Runner Forum

honda250xtitan · 10-21-2022, 10:18 AM

Quote:

Originally Posted by 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.
]

I used to build traction bars for some of the titan guys back in the day. I alwasy did one end with Heims and the other end with a poly bushing. those traction bars didnt twist as much as the 4runner links, but same idea. I'd love a full of arms from Mstudt, they look killer. Heims are pain to keep noise free with age but they work so well.

comtn4x4 · 10-21-2022, 02:13 PM

Quote:

Originally Posted by 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.

I haven't driven it too much yet. That being said not significantly different. Possibly a bit smoother through the travel. I'll need to drive it some more and get it off road. It appears the driver's side arm was broken longer than the passenger side so I've been running with one for an undetermined amount of time. I sort of interested to see if I notice a difference with both installed

comtn4x4 · 10-21-2022, 02:14 PM

Quote:

Originally Posted by honda250xtitan

I used to build traction bars for some of the titan guys back in the day. I alwasy did one end with Heims and the other end with a poly bushing. those traction bars didnt twist as much as the 4runner links, but same idea. I'd love a full of arms from Mstudt, they look killer. Heims are pain to keep noise free with age but they work so well.

Yeah we'll see with time how noisy they get. I'm tempted to get his lower arms too

mrblah · 10-21-2022, 08:56 PM

Quote:

Originally Posted by comtn4x4

Yeah we'll see with time how noisy they get. I'm tempted to get his lower arms too

DOOEEEEEEIT...they look beefy!!!!

comtn4x4 · 10-21-2022, 09:30 PM

Quote:

Originally Posted by mrblah

DOOEEEEEEIT...they look beefy!!!!

Lol, if I didn't already have aftermarket arms I'd jump on it

mrblah · 10-22-2022, 11:06 PM

Quote:

Originally Posted by comtn4x4

Lol, if I didn't already have aftermarket arms I'd jump on it

same here. I don't wanna upgrade the upgrade unless i break the upgrade which is unlikely for me

TRD PANTHER · 10-23-2022, 12:02 AM

I don’t have KDSS, but, I am curious if your KDSS/Trac bar was set properly and wasn’t putting undo stress on the links or contributing to it because the angle was off.

honda250xtitan · 10-23-2022, 10:07 AM

Quote:

Originally Posted by TRD PANTHER

I don’t have KDSS, but, I am curious if your KDSS/Trac bar was set properly and wasn’t putting undo stress on the links or contributing to it because the angle was off.

all itll do is hit the panhard bar. the piston has enough play to move around. wont be contributing to the issue IMO.

TRD PANTHER · 10-23-2022, 02:43 PM

Quote:

Originally Posted by honda250xtitan

all itll do is hit the panhard bar. the piston has enough play to move around. wont be contributing to the issue IMO.

The Panhard bar is what I was referring to after his lift. I thought he had an aftermarket adjustable panhard bar that is called a trac bar with KDSS. I don’t have or know much about the KDSS system except that it offers less roll and better handling characteristics.

comtn4x4 · 10-23-2022, 03:22 PM

Quote:

Originally Posted by TRD PANTHER

The Panhard bar is what I was referring to after his lift. I thought he had an aftermarket adjustable panhard bar that is called a trac bar with KDSS. I don’t have or know much about the KDSS system except that it offers less roll and better handling characteristics.

I do have the Sonoran Steel KDSS adjustable trac bar. It's positioned as it is supposed to be. I also have a KDSS spacer block. Are they what is causing the issue? Good question, I don't think so bit it's certainly possible.

Honestly there are so many different rear suspension mods on my truck and many done because of damage I've incurred plus 120,000 miles it could really be anything or combination of things. Since no one else seems to have had this problem it's probably some combination of things and shitty luck. But... really, the bars did last 120,000 miles (my rig has been lifted and wheeled all but 1,000 of those miles. ) and it was only a couple hundred to repair. Could have been much worse.

comtn4x4 · 10-23-2022, 03:31 PM

Quote:

Originally Posted by mrblah

same here. I don't wanna upgrade the upgrade unless i break the upgrade which is unlikely for me

Although, shiny new parts are lots of fun!
Looking at the Overland Custom Design lower control arms, I'd have to do some more investigation. If you orient the heim joints so that you can access the zerk fittings they'll be in a potentially vulnerable position on both the axle and frame mount. And it looks like on the frame mount end the zerk would be really close to my mount guard during down travel. If you turn the heim so the zerk is on the other side you'd have to remove the arm every time you wanted to grease or inspect it. I've already had problems bashing those areas. Maybe @MStudt can speak to that.

honda250xtitan · 10-23-2022, 03:50 PM

Quote:

Originally Posted by TRD PANTHER

The Panhard bar is what I was referring to after his lift. I thought he had an aftermarket adjustable panhard bar that is called a trac bar with KDSS. I don’t have or know much about the KDSS system except that it offers less roll and better handling characteristics.

thats why i said its not an issue, piston has plenty of play in the way the piston is mounted, the potential issue is the kdss bracket might contact the bar but itll just clunk and shove the piston forward. panhard bar=trac bar, regardless of kdss or not. potato tomato? lol

TRD PANTHER · 10-23-2022, 04:09 PM

Quote:

Originally Posted by honda250xtitan

thats why i said its not an issue, piston has plenty of play in the way the piston is mounted, the potential issue is the kdss bracket might contact the bar but itll just clunk and shove the piston forward. panhard bar=trac bar, regardless of kdss or not. potato tomato? lol

I need to watch a video on the KDSS system. Thanks

comtn4x4 · 10-23-2022, 04:23 PM

Quote:

Originally Posted by TRD PANTHER

I need to watch a video on the KDSS system. Thanks

You could start here:

Best video explaining KDSS

TRD PANTHER · 10-23-2022, 04:59 PM

Quote:

Originally Posted by comtn4x4

You could start here:

Best video explaining KDSS

Thanks for that link. It was a very interesting and informative video on the KDSS system. That helped a lot. I always hear the pros and cons of the system, but I honestly don’t pay much attention since I don’t have it. I see the pros. What are the cons?

Site Navigation