SPC Rear Lower Control Arms? (1 Viewer)

[timjax]

What are the advantages of the SPC Rear Lower Control Arms? I understand it's thicker tubing and less likely to get bent on the trail, but I'm wondering if there's any other added functionality.

For example: Do they offer greater off-road flexibility/droop/articulation? Are the bushings and joints lower maintenance and offer added longevity versus stock? Does it improve road and trail manners/handling after a lift? Are they useful for alignment (on a solid rear axle...)?

The description says "for superior flexibility off road" but I'm not exactly sure how or how much. It also mentions special bushings to isolate axle noise, but I'm not sure if that's an improvement over stock either.

They're also available through Slee.

 

[JohnJB]

So Rob sawed my stock arm open, it was also 3/16" DOM if I recall correctly. Obviously can't speak to the metallurgy itself, guessing that's where SPC believes they are getting the additional strength.

In theory you should get more flex (in terms of ease, not actual increased travel) on the axle side with the xAxis joint but this is nothing you'll notice day to day, only at the limits of articulation and I'm sure it's marginal. The frame side, it's a rubber bushing like stock.

I replaced mine as I bought them for a significant discount and my stock bushings were 10 years old with 100k miles. In reality, it was a waste of money since it's not like I was replacing a bent one. My advice is don't bother with them unless you've damaged yours or just like tinkering.

 

[Mogwai]

I'd think if you were going to drop the coin you may also want something adjustable. There are a few that make them, I know Trail-tailor does but they appear to be out of stock at the moment. Rear Lower Control Arms

 

[timjax]

So Rob sawed my stock arm open, it was also 3/16" DOM if I recall correctly. Obviously can't speak to the metallurgy itself, guessing that's where SPC believes they are getting the additional strength.

In theory you should get more flex on the axle side with the xAxis joint but this is nothing you'll notice day to day, only at the limits of articulation and I'm sure it's marginal. The frame side, it's a rubber bushing like stock.

I replaced mine as I bought them for a significant discount and my stock bushings were 10 years old with 100k miles. In reality, it was a waste of money since it's not like I was replacing a bent one. My advice is don't bother with them unless you've damaged yours or just like tinkering.

Oh gotcha, no added thickness I see. Good to know.

Do you know how the xAxis joint adds flex?

The SPC UCA's for example greatly help when lifting for alignment as well as safer angles for suspension components. Do you feel the SPC upgrade may be worth it in the long run by adding reliability versus stock with higher quality components or especially so when combined with a lift?

I'd think if you were going to drop the coin you may also want something adjustable. There are a few that make them, I know Trail-tailor does but they appear to be out of stock at the moment. Rear Lower Control Arms

Good point. Would it being adjustable increase the maintenance needed to run them long term? I see they're greasable and fully rebuildable.

I guess it's also worth mentioning the other adjustable RLCA's by:
Icon
Metal Tech
Total Chaos


I believe @Markuson also runs these SPC RLCA's, so maybe he can chime in on his take on them.

 

[Mogwai]

I'm no suspension expert but the adjustable piece shouldn't affect maintenance per se, it's just a threaded end that allows you to extend the length, then lock it down. I replaced the rear pan hard with a tough dog adjustable (adjusted slightly longer) after lift to get the rear wheel track back in line w/ the front.

But back to the RLCAs, I'd think the benefit would be to what you mentioned earlier, when you lift your vehicle you're raising one end of the triangle, but not extending the other (RLCAs). You could extend the RLCA which should in theory yield some benefit (longer link = longer travel?). Someone not too long ago also sent around adjustable control arm links, haven't seen them used/talked about much on here, but same idea, get your trig geometries back closer to stock ratios. May consider those as well if you're going this route. I'd ask @Taco2Cruiser to chime in.

Edit: saw this note under the TC kit: "Capable of more wheel travel with custom shocks and mounts." -- makes sense, you're basically trying to make everything longer if you're looking for "more...whatever".

 

[Markuson]

I believe @Markuson also runs these SPC RLCA's, so maybe he can chime in on his take on them.

Re my rear SPC RLCAs...
The only reason I added those was because I bent my stock RLCA on one side from boulder impacts. I personally don’t the need the need for lengthened units. The SPCs are definitely claimed as stronger than stock...but they basically look like stock...so no fancy look, and tgat’s fine with me.

If I add anything adjustable in back, it would probably be adjustable panhard rods to keep the truck a bit more centered in the rear... but again...its not really a big deal on my truck because I intentionally avoided over-lifting. I soppose if I ever destroy a panhard rod somehow, I’ll probably go ahead & replace with an adjustable, but but at this point, it’s just not a glaring need.

 

[JohnJB]

Oh gotcha, no added thickness I see. Good to know.

Do you know how the xAxis joint adds flex?

The SPC UCA's for example greatly help when lifting for alignment as well as safer angles for suspension components. Do you feel the SPC upgrade may be worth it in the long run by adding reliability versus stock with higher quality components or especially so when combined with a lift?

By design, they allow for greater angularity than a stock rubber bushing. A lot more than a single bushing contributes to articulation off road but the design essentially allows for more twist with greater ease at the axle side joint, I think they say something like 22 degrees in each direction.

Regarding the second question, I would suggest divorcing the idea of comparing them to the front control arms since you're talking IFS in the front and solid axle in the back. Yes, control arms both help locate the wheel relative to wheel well (frame really) but they also functionally operate differently between the two suspension types. An adjustable RLCA will help compensate for the altered geometry of lifting the vehicle but I haven't seen a lot suggesting the rear 2" is much cause for concern in terms of overall functionality, esp. when talking about a RLCA. I'd be more concerned with axle shift relative to the frame, aka panhard bar.

 

[RichardS]

I’ve never heard these referee to as “RLCA” I think they are normally called “lower links”. You can also replace the upper links and panhard bar. I’ve replaced them on my 4Runner after turning mine into boomerangs after a nasty line at Uwharrie. They tend to push the rear axle into a more neutral position after lifting and can help with fitting larger tires. Adjustable does mean additional maintenance (and an additional failure point) and I would opt for a fixed length.

 

[Taco2Cruiser]

I'd ask @Taco2Cruiser to chime in.

So... the RLCAs set the arc swing of the rear axle. Keep in mind the bump stop location is not changing. Regardless of a lift, the rear axle still swings in the exact same way. So you want to set the RLCAs to the exact same length as factory. That way, when under full compression, the rear axle housing still hits the center of the bump stop. This follows the same principle as tire size under a lift, a lift just changes the ride height. It doesn’t change suspension geometry (mounts don’t change), tire clearance, or compression stops.

With that, and the fact that the factory arms are also .188 DOM, I would not replace them. SPC does have a very nice X-axis joint for their RLCAs, but it is one of those “it briefs well.”A 200s rear axle is not going to be limited to articulation because of the factory rubber bushes. So while SPC’s advertising department says they are “strong” and give more “sweet flex,” the truth is... they won’t.

also, know that the factory frame mounts as not that strong, and I would not go past .188 DOM as you may be moving the failure point from the easy to replace control arm, to the expensive and harder to replace mounts.

Know for the Rear Upper Control Arms (RUCAs), those are used to set pinion angle. You only change that if you adjust the location of the transfer case rear output. Now one with a 200, is switching out their transfer cases (yet) so those being adjustable, also are not needed. Same goes for the rubber bushes they use. It simple is not going to change anything.

For the Panhard rod (lateral rod). Ok, this can be adjusted to recenter the axle housing when it sits at the new ride height from a lift. While it doesn’t effect trust angle, it’s nice to have a centered axle (if you just have to spend money). That said, a 3” lift on the rear still only needs .3” longer rod. So not like it matters much on an IFS truck (thats another discussion for solid front axles that have opposing panhard rod frame mounts, but we don’t)

if you got a panhard, get it from @TRAIL TAILOR as Jason brings in tough dog control arms. I’m not a tough dog fan, I have one anyway, but it has nice rubber bushes to limit vibration.

 

[RichardS]

Aren’t aftermarket lower links typically offset to provide additional down travel? It’s not much more than an inch or two.

 

[Markuson]

So... the RLCAs set the arc swing of the rear axle. Keep in mind the bump stop location is not changing. Regardless of a lift, the rear axle still swings in the exact same way. So you want to set the RLCAs to the exact same length as factory. That way, when under full compression, the rear axle housing still hits the center of the bump stop. This follows the same principle as tire size under a lift, a lift just changes the ride height. It doesn’t change suspension geometry (mounts don’t change), tire clearance, or compression stops.

With that, and the fact that the factory arms are also .188 DOM, I would not replace them. SPC does have a very nice X-axis joint for their RLCAs, but it is one of those “it briefs well.”A 200s rear axle is not going to be limited to articulation because of the factory rubber bushes. So while SPC’s advertising department says they are “strong” and give more “sweet flex,” the truth is... they won’t.

also, know that the factory frame mounts as not that strong, and I would not go past .188 DOM as you may be moving the failure point from the easy to replace control arm, to the expensive and harder to replace mounts.

Know for the Rear Upper Control Arms (RUCAs), those are used to set pinion angle. You only change that if you adjust the location of the transfer case rear output. Now one with a 200, is switching out their transfer cases (yet) so those being adjustable, also are not needed. Same goes for the rubber bushes they use. It simple is not going to change anything.

For the Panhard rod (lateral rod). Ok, this can be adjusted to recenter the axle housing when it sits at the new ride height from a lift. While it doesn’t effect trust angle, it’s nice to have a centered axle (if you just have to spend money). That said, a 3” lift on the rear still only needs .3” longer rod. So not like it matters much on an IFS truck (thats another discussion for solid front axles that have opposing panhard rod frame mounts, but we don’t)

if you got a panhard, get it from @TRAIL TAILOR as Jason brings in tough dog control arms. I’m not a tough dog fan, I have one anyway, but it has nice rubber bushes to limit vibration.

I’m glad you chimed in...because while responding above...it seemed to me like the RLCA would never need to change...since it still has to stay with the arc while compressing (unless it’s so crazy-lifted & CAN’T compress...like a bro-truck that clearly can’t bc of stupid levels of lift for lift’s sake).

Your panhard rod example (3 inches needing only 0.3” change) also confirms why I don’t feel I need to adjust it mine. Not even sure how much higher than stock my 2724’s put my rear at, but it’s not enough to spend the $ on an adjustable panhard (to me, anyway).

 

[Taco2Cruiser]

Aren’t aftermarket lower links typically offset to provide additional down travel? It’s not much more than an inch or two.

For the rear suspension on modern Toyotas’, the limiting factor is the shock. After that it is the anti-sway bar. Then the rear prop shaft (it just needs a good amount of contact to be safe, but like anything, you can push the limits.)

The control arms, that’s what I learned when getting my ASE certificates in college, so I refer to them as that, doesn’t mean that’s the only way. Links are typically reserved for steering components as they “link” things together that move. But control arms, “control the position of the wheels” that are in fixed positions. Here is a fun twist though, in the fabricating world, people refer to solid axle set ups as “links.” A 3 link, a 4 link, a 4 link with panhard.

Anyway, a lower control arms on a solid axle that is offset is really to get more ground clearance.

Anything can be adjusted, so none of this is gospel.

 

[lbbest]

I have them, they are heavy duty for sure and I like that they are regular bushings as opposed to heim joints that can make some noise. Completely unnecessary upgrade but recommend them.

 

[tominboise]

Completely unnecessary upgrade but recommend them.

This statement epitomizes the motoring enthusiast to a Tee.....not just 200's but all types.....Guilty of this myself many times over.

 

[Markuson]

This statement epitomizes the motoring enthusiast to a Tee.....not just 200's but all types.....Guilty of this myself many times over.

Ya, I guess. But in the case of RLCAs...unless you bend your OEM...it’s an upgrade that really offers no benefit except knowing you’ve replaced perfectly adequate OEMs. SPCs look and operate the same...so my 1.5 cents would be...spend that money elsewhere unless you bend your originals. Most folks never will.
But meh... -<TETO

 

[Taco2Cruiser]

Just as easy to bend SPC and it is OEM.