Trifecta Build Thread - KOH EMC, Cruise Moab, Rubithon

[Charles4x4]

Good thread on Pirate about stock 4600 solid axle Toyota truck
Toyota Racer #4611: KOH Stock Class Build - Pirate4x4.Com : 4x4 and Off-Road Forum

Thanks. Here's another one on Pirate that I found where a Toyota IFS 4600 rig was discussed at length, but never acted on.

IFS 4600 class yota - Pirate4x4.Com : 4x4 and Off-Road Forum

Also, I believe a supercharger (they discuss for the 3.4 v6 in that thread) would count as forced induction right? Turbo and Superchargers are both by definition Forced Induction per Google

 

[Drunner97]

For those not familiar with the KOH EMC 4600 class, here are the restrictions (per Rule Book v4.4) in addition to stanard safety, conduct, and other restrictions applying to all classes:

4600 Stock Class Restrictions (Summarized):

Body:
- Complete Unmodified stock frame
- Complete stock body (can cut holes for roll cage and rocker panel protection)
- Half doors are acceptable but must open and close
- Stock glass not required
- Front/Rear inner fenders must be complete
- Fenders can be trimmed to no more than 2" gap from tire at full compression
- No more than 1" body lift
- Factory Headlights are required
- Aftermarket bumpers are fine or can be eliminated

DriveTrain:
- Stock engine (no forced induction) required but performance mods allowed
- Stock transmission required
- Any transfer case is permitted
- Any axles are permitted
- Any driveshafts are permitted
- Mechanical steering required but hydro assist okay

Suspension:
- Wheelbase cannot be lengthened more than 3"
- Suspension configuration must remain consistent from stock (leafs must stay leafs, coils must stay coils, coilovers must remain coilovers) and no fancy leaf configurations (quarter eliptical not allowed)
- Suspension linkage can be changed in any configuration
- 1 shock per tire/wheel at max of 2.65" diameter and 14" stroke with no air bumps allowed
- No bypass shocks and shocks must connect axle to chassis

Other:
- Max 35" tire

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The 4500 Modified Class has much fewer restrictions (and is therefore much more competitive):

4500 Modified Class Restrictions (Summarized):
- Must look somewhat like a OEM production vehicle of some kind
- Stock frame from engine mounts to behind front seat must be retained
- Mechanical steering required but can have hydro assist (no full-hydro)
- 2 shocks per tire/wheel at max of 2.65" diameter and 14" stroke with air bumps allowed in this class
- Max 37" tire

Can't go wrong with a 4th gen and those restrictions. You can easily get custom made coils for the rear to handle the shock travel you'll need for the long travel sections and can do a Dirt King front long travel to match it but still retain 4wd capabilities. 35s will fit with a body lift and no cutting, or no body lift and cutting. My biggest problem with 35s right now are I'm smashing the hell out of the top of my wheel well, but I'm also sitting a little low in the front so I'm hoping another .5-1" on the coil overs will alleviate some of that. You'll want gusseted spindles for sure otherwise you risk bending or breaking them.

Either option 1 or 2. The rock sections will suck in option 1. The desert sections will suck in option 2. I think you'd have more luck getting further through the race in option 2. Lap 1 is a huge desert loop. Most guys (IFS and solid axle) can make that loop as long as you don't think your Robby Gordon out there in the open desert. It's a hard thing not to do. Trust me on this. Going fast in the desert is addicting and expensive. Even in my 84 4Runner on 40's, it was a blast ripping through the desert. But the big whoop sections had me down to 10-15 mph and on the bump stops on every hit.

Guess in the end is what do you feel like dumping a lot of $ into? If KOH was strictly your end goal, I'd say option 2. But since you want to wheel Moab and the Rubicon, option 1 is probably the better choice.

I jumped mine a few times by accident last weekend bombing around the desert and she handled it okay. I'm pretty heavy too.

 

[Inv4drZm]

4600 Stock Class Restrictions (Summarized):

Body:
- Complete Unmodified stock frame
- Complete stock body (can cut holes for roll cage and rocker panel protection)

Does this mean no body mount chop? Might be an issue if it does...

With long travel IFS you might be able to push the 35" tires forward enough. Or run smaller.

 

[Drunner97]

Does this mean no body mount chop? Might be an issue if it does...

4.5+ caster maybe ? I was barely rubbing my driver side with 3.9ish* but I was hitting my frame rail.

 

[Inv4drZm]

Can't change or add link mounts either or weld in custom crossmembers or plate the frame at all? Add shock hoops? Yeesh kinda restrictive if that is the case.

 

[Charles4x4]

Does this mean no body mount chop? Might be an issue if it does...

With long travel IFS you might be able to push the 35" tires forward enough. Or run smaller.

"Stock body mounts may be modified or eliminated, with the following limitations: The relationship of the body to the frame must remain within 1" of stock configuration, as originally manufactured. Stock body mounts shall not be modified or eliminated for any reason other than to allow any part of the roll cage to pass through the body in order to securely attach to the chassis."

Does this help? I was assuming fiberglass fenders (permitted) would help clear the 35s. Also, wheelbase can change up to 3" from stock.

 

[Charles4x4]

Can't go wrong with a 4th gen and those restrictions. You can easily get custom made coils for the rear to handle the shock travel you'll need for the long travel sections and can do a Dirt King front long travel to match it but still retain 4wd capabilities. 35s will fit with a body lift and no cutting, or no body lift and cutting. My biggest problem with 35s right now are I'm smashing the hell out of the top of my wheel well, but I'm also sitting a little low in the front so I'm hoping another .5-1" on the coil overs will alleviate some of that. You'll want gusseted spindles for sure otherwise you risk bending or breaking them.


I jumped mine a few times by accident last weekend bombing around the desert and she handled it okay. I'm pretty heavy too.

Good to know. Looked at Dirt King - looks similar to Total Chaos and Camburg. Still adds 7" to stock width, which is too much for trails.

4600 rules allow 1" body lift, fiberglass fenders, or trimming of the fenders to within 2" beyond the tire height at full compression.

Agreed completely on the Gusseted Spindles - not many of the kits have these. Is there a separate manufacturer for these?

 

[Drunner97]

"Stock body mounts may be modified or eliminated, with the following limitations: The relationship of the body to the frame must remain within 1" of stock configuration, as originally manufactured. Stock body mounts shall not be modified or eliminated for any reason other than to allow any part of the roll cage to pass through the body in order to securely attach to the chassis."

Does this help? I was assuming fiberglass fenders (permitted) would help clear the 35s. Also, wheelbase can change up to 3" from stock.

Fiberglass should help with the up travel and the usual fender trimming required for running 35s. I've already trimmed about 1" and still need to do at least another inch off my fenders.

 

[Drunner97]

Good to know. Looked at Dirt King - looks similar to Total Chaos and Camburg. Still adds 7" to stock width, which is too much for trails.

4600 rules allow 1" body lift, fiberglass fenders, or trimming of the fenders to within 2" beyond the tire height at full compression.

Agreed completely on the Gusseted Spindles - not many of the kits have these. Is there a separate manufacturer for these?

TC has a spindle gusset kit. That's what I'm running now.

 

[Charles4x4]

Can't change or add link mounts either or weld in custom crossmembers or plate the frame at all? Add shock hoops? Yeesh kinda restrictive if that is the case.

No, you can. Links can be changed in any configuration along with their mounts on the frame. See below.

"Coil-springs and related suspension linkage may be modified or eliminated and replaced with any coil-springs and linkage, and may be installed in any location and orientation, with the following limitations and exceptions: Coil- springs must be connected directly to the axle assembly and chassis and shall not be mounted in any way so as to yield any type of mechanical advantage, unless factory-equipped. Coil- springs shall not be replaced with any type of coil-over shocks, unless factory- equipped (if so-equipped, factory coil-over shocks may be replaced with aftermarket coil-over shocks)."

I've wondered about the shock hoops - if they are technically part of the "chassis", then we're good there too. See below.

"Shock absorbers of any make/model/type are permitted and may be installed in any location and orientation, with the following limitations and exceptions: Only one shock absorber is permitted per wheel/tire (not including spare tires). Shock absorbers shall not be larger than 2.65" in diameter (outer diameter of shock-body) and shall not be capable of any more than 14" stroke. Position-sensitive shocks (including bypass shocks of all types) are not permitted. Shock absorbers must be connected directly to the axle assembly and chassis and shall not be mounted in any way so as to yield any type of mechanical advantage, unless factory-equipped (mounting shock absorbers off-vertical is permitted and shall not be considered a mechanical advantage)."

 

[Charles4x4]

TC has a spindle gusset kit. That's what I'm running now.

Great, I'll need them.

 

[Charles4x4]

Update: The 1st Gen SR5 Turbo goes up for auction next week on Bring a Trailer. Fingers crossed the seed money for this build is in place in the next few days.

Also still working on sponsorships - I’m open to any and all suggestions! I’ve reached out to 5 groups so far...

 

[Drunner97]

Update: The 1st Gen SR5 Turbo goes up for auction next week on Bring a Trailer. Fingers crossed the seed money for this build is in place in the next few days.

Also still working on sponsorships - I’m open to any and all suggestions! I’ve reached out to 5 groups so far...

Start plastering it all over IG. You should pick up sponsers right quick. That's how all the overland groups are doing it these days. Hahaha.

Sent from my Nexus 6 using Tapatalk

 

[Charles4x4]

Start plastering it all over IG. You should pick up sponsers right quick. That's how all the overland groups are doing it these days. Hahaha.

Sent from my Nexus 6 using Tapatalk

Never used Instragram in my life, but also never too late to start! Will start getting familiar with it once I pick up a 4th gen.

 

[Inv4drZm]

Great, I'll need them.

FYI Get the gusset kit that keeps the sway bar. It's more expensive but the swaybarless kit tends to crack the spindle easier. Puts all the stress on one spot.

 

[Charles4x4]

FYI Get the gusset kit that keeps the sway bar. It's more expensive but the swaybarless kit tends to crack the spindle easier. Puts all the stress on one spot.

Makes sense. Honestly wish TC was carrying these like Solo is. They seem much beefier than the gusset kit, but maybe it's just the overall look...

 

[Drunner97]

These are the tc gussets with sway bar.

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[Charles4x4]

These are the tc gussets with sway bar.

Sent from my Nexus 6 using Tapatalk

Thanks, very helpful to see them installed.

 

[Charles4x4]

Another Update:
Over the weekend I started thinking about the KOH Rulebook and the Trifecta Build. I concluded that the race organizers wisely designed the 4600 rules to balance two things:

1) Retaining the look/feel on OEM rules, allowing vehicles to cater to the majority of "Every Man's" vehicle owners out there and allowing sponsors to showcase their products in the "World's Toughest Off-Road Race"

While also:

2) Permitting an "anything goes" mentality for the critical, most prone-to-failure portions of the drive train to give 4600 class rigs a fighting chance to actually survive the race.

With this in mind, I concluded that participants (me included) better take advantage of any and all permissions in the rule book in order to have the best chance of survival for their sponsors and themselves.

So, for the Trifecta Build, this means we cannot cut corners on critical drive-train and performance areas of the build just to try and save a few bucks.

Therefore, here is my latest build plan after a weekend of research:

Vehicle: '06-09 Toyota 4Runner v8 Sport

Front:
- Front IFS Long Travel Kit (3.5" to keep Track Width 7" from Stock)
- Currie F9 IFS Front Differential (4.88s or 5.29s and ARB Locker)
- RCV Ultimate IFS CV Axles
- Front Fabricated/Gusseted Spindles, Steering/Clevis, and Shock Hoop, and other Gusset/Bracing upgrades
- Front 10-14" King Dual Rate Coilovers with RR
- HD Steering (Custom or Modified Tundra Rack)
- HD Driveshaft

Rear:
- Aftermarket Housing, Toyota 9.5" Diff, 4.88s or 5.29s, ARB, Chromoly Shafts
- Rear HD 4-Link Kit (Aftermarket HD links or Custom 4-link with factory fuel tank out of the way)
- Rear Long Travel Progressive Rate Heavy Coil Springs
- Rear 10-14" King Shocks with RR

Drivetrain:
- Stock Toyota 4.7L V8
- Stock Automatic Transmission
- Atlas II Transfer Case
- HD Driveshafts (F/R)

Other:
- 35x12.50r17 Tires (must be tall - as close to a true 35 as possible)
- 17" Beadlock wheels
- Front Aluminum Bumper (Pelfreybilt or Addicted Offroad)
- Rear Aluminum Bumper (4x4 Labs or Other)
- HD Sliders and possibly Boat Side protection below door sills
- Warn Winch, Full Length Skidplates, Upgraded Bump Stops, Brake Lines, etc.
- Spare Tire, Aluminum Fuel Cell, & Battery in the Cargo Area
- Fiberglass Fenders (4.5" Bulge)
- Roll Cage, Harnesses, Suspension Seats and other Safety Stuff Required
- LED Lights (F/R), Spare Parts, and other Race Stuff Required

Honestly, I simply cannot afford the build above. But both KOH EMC and the Toyota "Every Man" Enthusiast across the world deserves to see it happen.

So, I'm ramping up my efforts and proactively reaching out to key sponsors and spreading the word. I'm also going to get on Instagram soon to amp up promotion more and possibly do other forum threads. I believe if someone has a great idea and is passionate enough and committed enough to work hard to see it to fruition, others will rally around it and help make it happen, together.

If anyone has any connections with potential sponsors or other "outside the box" ideas to help ensure this happens, I'm all ears!

49 Weeks To Go!

 

[Inv4drZm]

This will be badass. Would love to see that front diff in there. Please swap to at least 37's when wheeling in Moab or Rubicon.

I'm questioning the aluminum bumpers. Just not sure how long they will last, and not sure if you can make the rear bumper strong enough out of aluminum with a tire swingout.

Whichever type of spindle you go with, a 0 offset wheel is about as close as you can get to the aftermarket spindles (depends on the wheel width too I guess). Not sure about the weld-on gussets. If you can, try and find beadlocks that run as close as possible to the spindle to keep your width down. You will keep the same amount of travel while not being so wide.

05'-09' are the years they had the vvti V8 motors, not sure why you list 06'-09'.

If you are looking into weight savings here is the list I have made w/ #'s. I've been looking into lightening up my truck where possible.

-They make 2" solid aluminum suspension links threaded on both ends for joints. If you do the math vs 2x.25 steel tubing you save like 20lbs or so with a long 4-link setup (unsprung mass). Just as strong more or less and some race buggies/trucks are running them. Couple hundred $ more. Heat treated 4140 Chromoly tubing would be the lightest but most $.

-I'm looking into 1/8" AR400 skids for mine. My 3/16" steel skids are 115lbs. 1/8" steel are 81lbs, and 1/4" aluminum is 60lbs for the set of 3. The AR400 skids would be as strong as 3/16" steel skids, stupid hard so they slide over rocks really easily which aluminum doesn't. Nobody makes AR400 skids so they would need to be custom made.

-Racing seats I'm guessing are lighter than stock. Of course you could probably get rid of the rear seats and passenger front seat for racing. Rear seats are 84 lbs.

-Fiberglass fenders are lighter. They make fiberglass hoods for Tacomas but not 4Runners as far as I know. They won't fit ours unless you swap headlights/ grilles/ and fenders with them (is possible).
Link 1
Link 2

-Remove factory roof rack and towing accessory. Have receiver tube integrated into rear bumper. Remove spare tire winch (that thing is heavy!)

-Fuel cells will be lighter of course, since they carry less fuel and need a smaller or no skid plate depending on location. Gas weighs 6.2lbs/gallon.
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