RCLT HD 2.75" - Travel Numbers and Notes

I know you like your research, and here's the hard numbers since you've been considering this kit for the DP. @Sociopenguin

 

I honestly have no clue wtf I'm doing but I'm pretty happy with how my truck performs for my usage.

 

Great write up dude! I wish I'd taken the time to do this during my install, but I had just finished the rear and hadn't wheeled in months at that point and wanted to get it done. I see what you mean about how changing the angle of the outer TRE mount would allow for more uptravel. I haven't taken my RCVs apart yet, but I wonder about the possibility of machining the inner cup and gaining a bit more downtravel. Have your thoughts on the 200LC rack changed at all?

 

I perused this one as soon I saw it.

 

Hey, you're just practicing theory is all. For Science!

 

Physics being discussed on tacomaworld. Wow.

 

Guessing you never saw the CMC threads where people were calculating impact forces during a crash.

 

yeah but those discussions are dumb…. If someone really thinks that piece of 2 x 2 is gonna be the life saver in a crash….

 

Big tars are just big pillows and should be welcomed into the cab with you.

 

It appears you are thinking of things in a static context vs a dynamic context. The best way to think about springs is how much energy they can absorb and how much stored energy they have. So in very simple terms if there are two shocks on the front (L&R) both with 600lb rate springs and both are compressed 7"s than we can conclude each front wheel/tire has 4200lbs of energy being transferred into them then into the ground. So 4200 x 2 = 8400lbs force which is close to 1 1/2+ times what the vehicle might weigh.

 

I’m going to regret getting involved in this discussion, but…. I agree with you except for your use of the word energy. Pounds is a unit of force not energy. I think your example is inspired by Hooke’s Law which states that the resistive force applied by a spring is equal to its displacement (compression or extension) times a constant. This applies whether the mass is moving (dynamic) or not moving (static).

In any case, yes I agree, if a 600 lb/in spring is compressed 7” then it is applying 4200 lbs of force both to the ground and to the truck.

F = kx

https://en.wikipedia.org/wiki/Hooke's_law

 

Using a Laplace transform to state your case or just using Eigenvalues in a sentence will automatically constitute as a mic drop. Doesn’t even have to be accurate. 1,2,3 go!

 

It's what made me hesitate to modify mine. When I went to larger offset wheels I had to unfortunately and I'm still rubbing the corner of it at stuff. Need to make sure my caster is set correctly, pretty sure my cams backed off last wheeling trip because Firestone bent my tabs.

 

Should read the whole conversation

 

Hello @Tacoma1192 and TW!

BigMike from Marlin Crawler here. Would like to chime in first to thank Kyle for the awesome write-up! I've wanted to get a stock rig to do a measuring session like this so thank you very much for the clear and detailed report!

I found the thread a couple weeks ago but have been busy getting things ready for our annual Round Up event. If this install was done by a shop we'd love to get you or the shop added to our Google Map of Installers!

I noticed one glaring issue straightaway which is that our included Low Profile Bump Stop (p/n MCSU-761) was not used for the measurements performed. Instead, the factory bump stop was used which I measure to be 47.5mm in total height, or 1.87". Your estimation of 0.875" compressed height is fair, yet, this is still taller than our entire uncompressed bump stop which is known to compress to 0.25".

This statement is incorrect as the stock bump stop is replaced with our provided Low Profile version (page 34), which is softer and known to have a loaded height of just 1/4". You measured that with out a bump stop, max travel is 11.875", and when I interpolate our bump stop compressed height of 0.25" in place of your 0.875" compressed height, I get 10.98" of travel [11.875 + (0.25 - 0) * (8.75 - 11.875) / (0.875 - 0) = 10.982...].

Therefore, the basic 'bolt-on' install of RCLT HD yields 11" of travel, not 8.75".

Our inverted LCA is designed for maximum ground clearance which gobbles up space below the bump stop frame bracket. Ideally, we recommend the "Best Solution" (page 34) of custom hydro bumps to maximize up travel, however, many customers appreciate the reduction so they may bolt-on up to size 38" tires with minimal or at best no frame or body trimming, which in the Toyota IFS world is beyond incredible. Such a claim prior to RCLT would likely get one banned, so its no small matter.

--
Edited to add this paragraph: I've seen comments on why run RCLT HD in a performance-limited configuration, and you have to remember that not everyone is a hardcore rock crawler like you. Many RCLT HD customers are ordinary overlanders who take their family on trips with 37" tires for added comfort and capability, yet who also don't want to hack up stock body lines, carry spare parts, break down, or incur costs exceeding RCLT HD in just replacement steering racks (one customer replaced 8 stock racks before finding us!). Try to respect the fact that people value safety, reliability, and piece of mind differently.
--

The rest of your analysis was fantastic and a lot of fun to read The larger motion ratio is for clearance between the coil and our honk'n massive knuckle (which is heavier than the LCA. What did you think of it? ) And the reason for the TRE knuckle angle is for our +3.50" version of the kit in conjunction with an up-coming product I've been testing since Easter Jeep Safari that requires the added down travel capability at the tie rod. Nevertheless, we make our own 5/8" double-sheer misalignment spacers and can just redesign them to get a degree or two more articulation and maybe hit that sweet 13" of travel you calculated. I think that would be killer for a +2.75" LT setup. Until then I've left the info on our site to be 12.5" as verified herein.

Now that we have real-world numbers, I've updated our advertised measurements as well as added a "Suspension Travel" section to our FAQ, referencing your moniker for the data! See FAQ here: https://www.marlincrawler.com/RCLTHD/FAQ Thank you again so much Sir!

Here is the relevant paragraph quoted, not including the preceding table of travel figures:

Reference: TC +3.50 advertises 12.5" travel and DK +3.50 as 13.5" (these being the only LT kits we ever see being used on trails). Taking the average of the two, (12.5" RCLT HD) / (13.0" average) = 96.15%




An important additional thing I'd like to note is that its NOT JUST FLEX when it comes to IFS, its also maintaining alignment geometry through that range of articulation. Unlike LT kits reusing factory knuckles, because we manufacture both new HD Knuckles and integrated HD MarRack steering, we designed our geometry specifically for a lifted static ride-height.

The difference is very important: Stock knuckles have geometry designed for the factory ride-height. As soon as you set your ride-height higher from stock and re-align to stock specs, the geometry becomes increasingly less stable throughout its range of motion. RCLT HD, on the other hand, has base geometry with a lift and added flex already incorporated by default.

So while having a lot of flex is nice, if your caster, camber, and toe goes wonky each time you drop or stuff a tire beyond what Toyota intended, that negatively impacts your turning radius, handling, tire wear, steering feel/feedback, etc., for LT kits that reuse stock knuckles.

This is no simple matter from a manufacturing perspective, as mentioned on our FAQ if we didn't have to incorporate the cost of our ridiculous knuckles, a higher manufacturing expense than two Dual Case setups, then even including our many additional use & strength features that boiler plate LT kits don't have our retail would only be $3,999.

Combined with our full replacement HD steering system, its the whole package that places the performance of RCLT HD in a league its own.

Regards,
BigMike


Extra:

My prototype +3.50" setup did pretty good against Solid Axle Jeeps on Metal Cloak's corner travel index trailer, which nullifies wheelbase. Would love to see someone like @Tac05, @RokMgmt, and others who performed more up-travel work than I did do this test. I suspect their travel numbers will be similar despite running our more narrow kit

https://www.youtube.com/watch?v=00wKv07d12w

 

I would like to see actual evidence of this.

 

Hey WormSquirts, thanks for the reply! Sure, that's no problem at all.

38x12.50R17 Milestar Patagonia M/T using our MCSU-761 Low Profile Bump Stops. Truck lives in Washington State, very friendly owner and happy to show it to ya in person





You can just barely see our Low Profile Bump Stop below the factory frame mount. Body mount 100% untouched and with factory paint. Spot weld seam on cab was hammered over flat.



Kit is broken in and achieves our full 32° of turning angle (64° sweep, which is 4° more than stock -- see FAQ for steering angle measurement table).

Runs full stuff up to our bump stops, now calculated to be 11" of travel, with no rubbing.



Here is a 5th gen 4R on 38s, however the owner trimmed in front for a better approach angle (common on 5th gens)



Also have the following examples of 37" installs which I don't believe have been trimmed and definitely no body mount rubbing. Chopping and/or relocating body mounts no need apply.





















Edit: Forgot this one. Here are 2x RCLT HD installs with 37" setups, and I believe the one on the right hasn't been trimmed.



Edit2: Hard to tell from this view, but maybe also not trimmed on 37s




We have a lot of kits out there but very few are on social media. Been on a mission hunting down more pics for our website, which we've been adding to the Media section here: https://www.marlincrawler.com/RCLTHD/media

Regards,
BigMike

 

Dont forget, nate with dirt lifestyle is on the 3.5 kit. Not the 2.75 that was measured by @Tacoma1192.

 

Any pictures of the inner wheel well with the wheel fully stuffed and turned to lock. Especially below the battery/washer fluid reservoir?

I would consider running fibreglass a body modification personally, but maybe that's just me.

 

Will request pics Also, I am planning a Canada snow wheeling trip and will pass near the rig and can see about getting pics myself!

For the sake of argument, I’ve edited my reply to say, “very minimal or at best no frame or body trimming”.

Edit: I love how we are pondering over how many millimeters to or to not trim for up to size 38s. When I just bought my Tacoma and joined this forum, all I ever saw were posts on “can I fit 285s without trimming.”

Regards,
BigMike