T-Rex A-Arms Installed

[Rob.G]

I just finished installing a set of the T-Rex A-Arms on my '23 Khaos 850. I tagged a rock a couple of rides ago with the right ski/knuckle and tweaked the right upper A-Arm. After a lot of research and reading the other big T-Rex thread here, I decided to give them a try.

Installation is fairly straightforward except that T-Rex's idea of instructions is an absolute JOKE. At least there was ONE useful tidbit, and that was to seat lower A-arm heim joints in all the way and then turn them out three full turns. A piece of info that WOULD have been helpful is if they'd mentioned that the gusseting on the uppers should be facing upward. If not, they will contact the shock spring at full droop. I noticed this after installing them the other way. At least swapping uppers is super quick 'n easy.

I haven't ridden with them yet; that happens tomorrow. I have one extra set of joints and two extra bolts for the uppers, and the tools to do a field repair. Let's hope that isn't necessary for a long time (ideally never).

Now here's what's odd. I took my old arms and compared them to one another and they do not appear to be bent at all. The bulkhead appears totally fine and the new arms installed without issue and everything appears to line up and is even side-to-side. Go figure. Maybe I have a complete extra set of arms now. Or I could sell them I guess.

The T-Rex arms are slightly heavier than stock... just slightly. i didn't try to weigh them. They aren't nearly as pretty either, but if they hold up better, I don't care.

 

[Empire087]

I will probably be putting a set on my matryx(have a set on my axys pro turbo), but my one complaint is its a pain to keep the upper heim joints tight. Otherwise, they work pretty well. Another thing you can do is order a few replacement joints from ebay, as they are around 13 a piece vs the 30 they charge. No difference in material or construction that i can see.

 

[Rob.G]

I picked up "FK" brand joints from Summit Racing after a tip from somebody here (sorry don't remember his name) and put them in initially... says they're SLIGHTLY stronger than the stockers, without being too strong. So I have the originals as my current spares. Good tip on the ebay ones, I'll have to do that to have extras. What I need to find are those little adapter sleeves you slide onto the upper bolts; I don't want to order from T-Rex because of their pricing, AND they seem to have a flat-rate shipping charge of $21 no matter what you order. Kinda nuts.

 

[Empire087]

I picked up "FK" brand joints from Summit Racing after a tip from somebody here (sorry don't remember his name) and put them in initially... says they're SLIGHTLY stronger than the stockers, without being too strong. So I have the originals as my current spares. Good tip on the ebay ones, I'll have to do that to have extras. What I need to find are those little adapter sleeves you slide onto the upper bolts; I don't want to order from T-Rex because of their pricing, AND they seem to have a flat-rate shipping charge of $21 no matter what you order. Kinda nuts.

Those should be stainless steel correct? I know on my originals, they where aluminum, and got loose all the time. With the newer style ones, they dont do that any more.

 

[Rob.G]

I'm not sure. They might be. Here's the link to one of them:

FK Rod Ends JMX10T FK JMX/JMXL Series Rod Ends | Summit Racing

Free Shipping - FK JMX/JMXL Series Rod Ends with qualifying orders of $109. Shop Rod Ends at Summit Racing.

www.summitracing.com

 

[mountaincat 800]

The aluminum spacer on the upper arm should be turned under the heim joint not on top. FYI

 

[Rob.G]

There's one on top of the bolt and one on the bottom. The arms are shipped with the bolts installed to show the proper way they go on, so I followed that.

 

[law.74]

The FK rod ends are quite a bit stronger than those that ship with the arms.
Not sure if “too strong”. Time will tell.
I posted strengths in an older “trex” thread.

Use a wrench on the rod end itself when tightening the jam nut. You could use blue threadlocker on that jam nut if desired. Clean threads completely first especially if applying anti-seize to rod end.

If/when the rod end breaks you likely won’t be able to reuse the jam nut anyway.
I recommend the anti-seize because the rod end (at least the cheapies) sheer at the jam nut arm interface. You will not have much if anything to grip with pliers so it needs to come out easily.

Like stated in other thread. I haven’t broken an FK joint yet, but also haven’t given myself the opportunity on that sled.

 

[mountaincat 800]

There's one on top of the bolt and one on the bottom. The arms are shipped with the bolts installed to show the proper way they go on, so I followed that.

Ok, and yet you decided to install the arms upside down? I was just trying to help. Whatever,

 

[madmax]

I have a brand new set (in the box) of Matryx 36" T-rex arms if anyone wants a set. $430 shipped to lower 48. I hit a rock side hilling yesterday and popped the upper heim joint off just like they're supposed to break. Fixed and riding again in a few minutes. Always carry and extra upper and lower joint, with an extra upper bolt (it always gets bent in a hit), extra mis-alignment spacers and tools to change them. You can buy all the parts from T-rex if you want.