Author Topic: Marlin Crawler's New Rock Crawling Long Travel IFS Suspension System (#RCLT)  (Read 10760 times)

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With the amount of extension required, do you think two outers would work if they used a slip-style shaft? Kind of like a driveline?

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  • Offline Rock Crawl'n
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So standard CV shafts and steering components are fine for a full 1" forward hub push?


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With products like this it will only help keep off-roading popular with the newer vehicles. Way to be innovators.
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  • Offline Dusty Trails
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Great design and nice to see such unique features specific to crawling!

Does the horizontal UCA ball joint limit any steering angle?
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  • Offline Dusty Trails
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Putting this on my FJ. Whenever you guys are ready!


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With products like this it will only help keep off-roading popular with the newer vehicles. Way to be innovators.

Only if a product has a use in more then a single type of off road use, and can be affordable to the general public.  Speaking of which, how many zillions will this upgrade cost? 


  • Offline Dusty Trails
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Can we please get this designed for the first gen Tacoma’s as well!?!?

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  • Offline Rock Crawl'n
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This is awesome, been wondering why it hasn't been done in the past. This is definitely going to change a lot for the modern Toyota IFS rigs. Is there potential for the lower level kits to use ball joints instead of uniballs in the future? SPC, JBA, and Icon offer a ball joint style control arm. And I know the uniballs dont last in winter climates. Could be a nice feature to offer for a lot of people who aren't in the best climates who would still like this kit for a DD that they want bigger tires for weekend adventures. For example my DD 4runner.

Looking forward to hanging out at the Roundup it's been a few years. Should have my Tacoma done and the Tacobox is ordered.
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Can bum...I have Uniballs in my upper Control arms and drive all winter here in Southern ontario.  I just spray them with dry Silicone lube and they have been fine for almost THREE years. :thumbs: If you use an oil lube they would be destroyed in weeks because it attracts and hold dirt and grit/salt.


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Release date and price for the different options?


  • Offline Dusty Trails
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Interested in this. BigMike are you coming back out to texas this year for the Toyota Jamboree with the new setup?


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How much will work on an 86?

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hold this. . .


  • Offline Rock Master
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That's a shitty design. May work for your mall crawler but that should have never left the shop knowing it's going into a race. Hope they come up with a good fix for the big race on friday.


  • Offline Dusty Trails
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Good question, but remember the inner CV is a tripod type which allows the inner axle to move in-and-out with wheel travel. So it has a more limited range of motion. :thumbs:

FAQ Round #2
Here come some responses to inquires we've received on other media outlets

Able to Daily Drive?
It will daily drive 100% like any other LT kit on the market. I will be daily driving our next RCLT HD kit starting next month. The biggest thing you will notice is increased body roll due to a lack of a front sway bar.

MarRack Included?
Only the RCLT HD Kit will come with the MarRack because factory steering cannot physically allow a knuckle to be moved forward 2-inches.
The RCLT Standard Kit, which moves the knuckles forward only 1-inch, is compatible with factory steering. You could chose to upgrade to the MarRack later if desired.

Shocks Included?
We are a Radflo distributor and will offer their LT shocks. The only thing to note is that the RCLT HD Kit will require LT shocks that have heim joints top and bottom.

Axle Shafts Included?
We will offer +2" and +2.75" extended length replacement inner axle shafts (you reuse your factory outer CVs) as well as +2" and +2.75" RCV Ultimate Shaft kits.

I wrote in reply #2, "Associated parts for installation", which refers to the stuff that makes up a kit such as bushings, sleeves, grease zerts, bolts, washers, misalignment spacers, limiting strap, brake lines and mounting clips, tie rod steering extensions (if applicable), and so on. I'll be editing that post with actual Kit Images as well as new categories and products added to our website this spring.

Can RCLT and/or RCLT HD be desert raced?
First and foremost, there are better kits for Baja than either RCLT which are optimized for Rock Crawling. Probably the best way to answer this is as follows:

Why the Standard Kit is better for Baja than the HD:
  • Less unsprung weight (mainly) due to factory knuckles being lighter than our HD knuckles
  • The factory knuckle's top vertical ball joint allows for a more compact UCA (narrow single shear vs wide double shear ball joint mount) so you'll likely to have a bit more maximum up travel prior to modifying sheet metal
  • Depending on tire size and wheel offset, would likely not require larger fenders

Why the HD Kit is better for Baja than the Standard:
  • The track width is 37.5% larger (2.75" vs 2") for better suspension travel and cornering/off-camber stability
  • Horizontal ball joints do not encounter misalignment issues so theoretically they allow more travel. If 2WD then substantially more travel
  • Double-shear ball joints and steering TRE connection are way stronger and can handle far higher loads (both hitting whoops and landing jumps)
  • MarRack is required and provides incredible steering strength, however it could be added to the Standard kit too

Plans to make this for the 3rd generation 4runner?

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  • Offline Rock Master
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That's a shitty design. May work for your mall crawler but that should have never left the shop knowing it's going into a race. Hope they come up with a good fix for the big race on friday.

This car was never built for the big race, only the EMC 4600 class.

That said, it has now been proven what was a weak link in the system. A possible solution I can see would be to leave it as the weak link (or fuse), but make it a bolt-on part of the spindle. This way, spare parts can easily be carried along and swapped out when the big rock is run into. Something so small should not have ended their race, IMO.


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BigMike, thanks so much for starting this thread.  It has been an honor and a pleasure to partner with You and Marlin Crawler on your RCLT kit.

For those who don't know me, I'm the owner of Steel City Racing and one of two individuals that has had the pleasure of "real world" testing the new Marlin Crawler RCLT kit.  The other person is Robert Otwell who helped me with all major custom fabrication on our Steel City Racing 4602 King of the Hammers build.  I mention Robert because he has 10x the desert racing and rock crawling experience that I have.

Let me cut to the chase.  This RCLT Kit is amazing.  It's provides unmatched ground clearance, strength, and performance.  There isn't anything else like it on the market today, period.  BigMike poured his Heart, Soul, and Experience into this product and it just plain performs.

Now, let me get to testing.  When the 4602 was finally ready for testing, both Robert (at a much faster pace than I was capable of) and I put it through Rough Desert terrain and some Moderate to Difficult Rock Crawling.  Our rear suspension is an amazing RockSolidToys 4-Link setup.  Unfortunatly our rear is limited by 4600 Ultra4 Class rules, specifically a large crossmember in front of the rear axle that we cannot touch that limits us by 3-4" of uptravel.  We run 2.5" Icon Coilovers in the front (Remote Reservoir and CDCV) and Icon Progressive Rate Coils and 2.5" Shocks in the rear (Remote Resevoir and CDCV).  We also have the first set of RCV Gen II Front Axle Shafts with the stock Toyota 8" Diff (4.56 Gears, ARB Locker, and MarlinCrawler internal upgrades).  We have a Dynatrac ProRock 60 in the rear that is setup by RockSolidToys.

The RCLT kit performed so well that our rear suspension, albeit it's limitation noted above, really struggled to keep up.  The front end floated over the rough desert and flexed like crazy in the rocks.  So much that we actually had to stiffen the front Icon Coilovers to hold the front back a little to balance it with our Ultra4 Rule limited rear suspension.

What's even crazier is that the prototype we have is being intentionally limited.  Our front Icon Coilovers were so big in diameter that we had to limit 3-4" of downtravel to keep the coils from hitting the spindle.  With this "tweak", our RCLT travel is going to be even more impressive.

Now, let's get to the race.  If you check out our build thread (, you will see a ton of pictures and videos of the RCLT kit in action.  We launched off the starting line, ramped a few feet in the air on the short course, and tore through the desert passing numerous 4600, 4500, and 4800 cars.  Spectators said it looked like we were "floating" through the rough stuff.  We were 2x smoother and faster than all the Solid Axle guys in desert.  We never made it to the rocks, but our testing on numerous Hammers trails during pre-running proved the suspension flexed and performed amazing.

Fast forward to Mile 25.  As someone posted above, we did experienced a steering connection failure at KOH.  If you know Ultra4, you know that we are literally "strapped in" beyond belief inside our Cage, 5-Point Harnesses, Neck Restraints, Fire Suits, and Helmets.  Simply put, we cannot see all that well and are trying to go FAST.

About an hour or an hour and a half into KOH EMC Lap 1 (75% of the total EMC mileage is in Lap 1) and many miles of rough terrain tackled, we were stuck behind a big blue 4600 Ford that was blocking our visibility.  I mis-judged a rock that we honestly never "truly saw" and took a hit it on our passenger front tire at speed.  We felt the vehicle hit fairly hard and our steering started to act funny.  The picture above is the final result - our steering tie rod end sheared off the spindle connection a few yards later and took us out of the race.

Could this section be stronger?  Yes.  Should I have not hit that rock?  Of course.  Big BigMike wanted his product tested in the most grueling venue possible - KOH.
 And KOH is the ultimate race to reveal any potential weak points before a product hits the market.  That's what R&D is all about.  Mission accomplished.

It's also worth of noting that I contacted 4-5 other Long Travel Front Suspension Manufactures early in the build process and none were willing to put their product on a KOH bound vehicle.  They all stated that their systems weren't "made for KOH level abuse".

So, what's next? 

Within minutes of me sending pictures of the damage to BigMike from the lakebed where we were towed after the break, he was already working on ideas and improvements to the RCLT kit.  From my perspective, the only "enhancements" that I can foresee are:
1) Strengthening the connection point for the Steering End to Spindle to avoid any future failures at this connection point.
2) Reinforcing the Lower A-Arm with a gusset at the rear lower side for potential high speed impact.
3) Shaving the width of the spindle in the middle areas to avoid contact with large diameter 2.5" coilovers, thereby gaining anoterr 3-4" of downtravel
4) Shaving a little more material off the lower Coilover mount on the A-Arm so large Gen II RCV boots clear it easily at 28 degrees.

That's it.  Nothing else is needed.

Our RCLT kit is on our 4602 car in my garage as we speak.  The MarRack to this day still works like new and took a lot of abuse helping get us out of that canyon with only one wheel steering.  The tie rod ends are as stout as they get and didn't flinch at impact.  The Upper A-Arm is solid.  The Lower A-Arm and Spindle will be perfect after these small tweaks mentioned above.  And the steering connection can be and will be strengthened.

In reality, Robert, Justin Reece, our pit crew team, and I were expecting many more problems with a "First Of It's Kind" Prototype like the RCLT kit.  Everyone who drove it and everyone who worked on it (including Justin Reece and Our Pit Crew Team, who won 4600 this year) were more than impressed.  It is extremely well envisioned, engineered, and built and only minor tweaks are needed before it's ready for market.

I am honored and excited to have been given the opportunity to run and test the RCLT kit and MarkRack on our 4602 car.  And I'm equally as excited to help BigMike make these enhancements and get the RCLT kit to Market.

If further proof is needed of our commitment to Marlin Crawler and the RCLT Kit / MarRack setup, we will be proud to run the newly enhanced RCLT kit on our 4602 car again in the 2020 King of the Hammers next year with a goal of finishing the race.

If you are considering this kit, IMO it's the ONLY Long Travel IFS Suspension and Steering setup capable of withstanding King of the Hammers level Desert Racing and Rock Crawling abuse while providing optimal performance in any terrain you could possible encounter.

Please feel free to ask me any questions in this thread or PM me for more details.
« Last Edit: Feb 13, 2019, 11:55:33 AM by Charles4x4 »
King of the Hammers 2019 Toyota 4Runner IFS 4600 Build


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