Iron Rock Rear A-arm

[vlad588]

Has anyone used this rear upper control arm, and what are the benefits of it and is it worth while installing?

 

[JeepJeepster]

I have it... Seems to be working good.

I have had the big nut come loose once but I assume its b/c I dont have a wrench that big and used a pipe wrench to tighten it.

 

[tommudd]

Good upgrade since JBA no longer makes his

 

[vlad588]

Good upgrade since JBA no longer makes his

But what exactly is upgraded, does rear suspension ends up with more articulation?

 

[Offroad Bob]

But what exactly is upgraded, does rear suspension ends up with more articulation?

Yes it does plus it won’t wear out the bushings every 6 to 8 months. I’ve been running one for about a year now and it’s much better than stock. If you get the optional flex joints, it allows it to transmit more road noise but that’s why I have a 300 watt stereo so I can drown it out. I too had problems with the adjusting nut on the mount to the rear end coming loose so I took a cold chisel and boogered up one thread lightly to stop it from backing off. Locktite didn’t hold it

 

[vlad588]

What about the their heavy duty adjustable lower control arms, are they worth getting and whats the benefit of being adjustable?

 

[vlad588]

Yes it does plus it won’t wear out the bushings every 6 to 8 months. I’ve been running one for about a year now and it’s much better than stock. If you get the optional flex joints, it allows it to transmit more road noise but that’s why I have a 300 watt stereo so I can drown it out. I too had problems with the adjusting nut on the mount to the rear end coming loose so I took a cold chisel and boogered up one thread lightly to stop it from backing off. Locktite didn’t hold it

Are these flex joints worth getting, especially considering the extra road noise?

 

[vlad588]

Yes it does plus it won’t wear out the bushings every 6 to 8 months. I’ve been running one for about a year now and it’s much better than stock. If you get the optional flex joints, it allows it to transmit more road noise but that’s why I have a 300 watt stereo so I can drown it out. I too had problems with the adjusting nut on the mount to the rear end coming loose so I took a cold chisel and boogered up one thread lightly to stop it from backing off. Locktite didn’t hold it

Are these flex joints worth getting, especially considering the extra road noise

 

[Offroad Bob]

If I still had a stock A-arm I’d be changing the bushings and ball joint again. It is easier to buy a whole new arm. Mine is still tight with no slop in it. I have the adjustable lower arms too. They have shown no sign of wear yet. My stock lower arms also had the bushings wear out where it attaches to the unibody. When that happens the rear end is able to “walk” around so when you accelerate, the rear end would shift. It would feel like the rear was sliding or you had a low or flat tire. Same thing would happen when you let off the gas or applied the brakes as it would shift the other direction. It was very unnerving to drive even after I got used to it doing that. Again I opted for the flex joints over the stock bushings on the lower arms. I just set the new arm next to the old ones and adjusted them to the same length. After installation you need to get the pinion angle checked to make sure the rear diff and the transmission are on the same plane with each other so you don’t wear out u-joints and pinion bearings and seal. I’ve added pics of the flex joint unassembled and installed. The joint has two poly half’s that encircle the joint and then are clamped together to hold the joint. It kind of resembles a U-joint with only one axis.

 

[Johnny O]

Has anyone used this rear upper control arm, and what are the benefits of it and is it worth while installing?

Worth every penny. Better bushings and such. Don’t care that it’s adjustable, me.

 

[Mshack]

If I still had a stock A-arm I’d be changing the bushings and ball joint again. It is easier to buy a whole new arm. Mine is still tight with no slop in it. I have the adjustable lower arms too. They have shown no sign of wear yet. My stock lower arms also had the bushings wear out where it attaches to the unibody. When that happens the rear end is able to “walk” around so when you accelerate, the rear end would shift. It would feel like the rear was sliding or you had a low or flat tire. Same thing would happen when you let off the gas or applied the brakes as it would shift the other direction. It was very unnerving to drive even after I got used to it doing that. Again I opted for the flex joints over the stock bushings on the lower arms. I just set the new arm next to the old ones and adjusted them to the same length. After installation you need to get the pinion angle checked to make sure the rear diff and the transmission are on the same plane with each other so you don’t wear out u-joints and pinion bearings and seal. I’ve added pics of the flex joint unassembled and installed. The joint has two poly half’s that encircle the joint and then are clamped together to hold the joint. It kind of resembles a U-joint with only one axis.

These pics makes the "stock" uca look cheap...I was only gonna purchase the uca, but now, I'm getting all 3 links. 125 miles a day, on rough country roads, this set up right here has to be a game changer. I did an oem uca replacement in Nov of 2021. 6 months later? Both bushings have torn internally on the front side of the bushing. Obvious that angle change from the height with the OME springs and Bilst shocks stresses these bushing. PROVEN RESULTS HERE! So, wife ain't gonna be happy, cause that changes the budget. But this set up has to be WAY better than the stock version. In my opinion.

Can't wait to get these parts!!!

By the way, did you order them in red?

 

[Offroad Bob]

They only come black as far as I know. I painted mine to liven it up down there !

 

[duderz7]

You can source the lowers from core 4x4 iirc, I think they look better,have more options and don't waste time putting useless sway bar mounts on them. I just recently got my recall lower links, but when they need replacement it'll be the core ones.

 

[vlad588]

If I still had a stock A-arm I’d be changing the bushings and ball joint again. It is easier to buy a whole new arm. Mine is still tight with no slop in it. I have the adjustable lower arms too. They have shown no sign of wear yet. My stock lower arms also had the bushings wear out where it attaches to the unibody. When that happens the rear end is able to “walk” around so when you accelerate, the rear end would shift. It would feel like the rear was sliding or you had a low or flat tire. Same thing would happen when you let off the gas or applied the brakes as it would shift the other direction. It was very unnerving to drive even after I got used to it doing that. Again I opted for the flex joints over the stock bushings on the lower arms. I just set the new arm next to the old ones and adjusted them to the same length. After installation you need to get the pinion angle checked to make sure the rear diff and the transmission are on the same plane with each other so you don’t wear out u-joints and pinion bearings and seal. I’ve added pics of the flex joint unassembled and installed. The joint has two poly half’s that encircle the joint and then are clamped together to hold the joint. It kind of resembles a U-joint with only one axis.

What about the extra road noise, is it really noticeable and objectionable at highway speeds that a radio needs to be cranked up?

 

[JeepJeepster]

The only time I notice the extra road noise is at low speeds. I don't notice it at all at higher speeds, other noises drown it out...

 

[Mshack]

They only come black as far as I know. I painted mine to liven it up down there !

Love the color

 

[JeepJeepster]

Speaking of looking good, it annoys me that they made it so the writing couldnt be read once the a arm is installed. Why wouldnt they want you to be able to read it while you were laying under there?

 

[tommudd]

What about the extra road noise, is it really noticeable and objectionable at highway speeds that a radio needs to be cranked up?

I run the JBA bolt on set up uppers on two of my KJs
and Core 4X4 lowers
drive over 95 miles a day, ( dirt roads /twisty, pot holed 2 lane roads ) small amount of somewhat more noise but hardly noticeable really, you get used to it

 

[65Corvair]

I have the rubber bushing'd version of it and I am very happy with it. The bushings cups are welded on at a slight angle so that ride height there is very little flex for the bushings, when compared to the stock upper rear control arm.
The adjustability is nice to get the output of the transfer case and the input pinion of the rear axle perfectly parallel to reduce driveline vibrations.

 

[vlad588]

How do you adjust the pinion angles if they are off after installing iron rock A-arm?