Cruzer's Re-Build for the Rubicon

oooooooooooh that is a wicked thing, holy cow, I wish I knew this exists when camping.

 

Just got home from picking up my new drive shaft from South Bay Driveline. $630
The front half of the shaft and the carrier bearing are the OEM parts, everything else has been replaced. Sealed U-joints and 1/8" DOM steel for the last half shaft. Only zerk fitting is for the slip yoke.

Can clearly see the rear shaft being more slim than the front.









My original drive shaft is way out of balance and is making a lot of noise:

 

Niiiiice! Excited to see how this one holds up.

I used them ages ago when I busted the driveshaft on my first Tacoma. Great shop!

 

I do plan to beat it up

 

I never would have guessed!


Ps: no update on the Fiesta Island meet yet, but I’ll keep you in the loop.

 

lets see a neutral drop to break it in!

 

Looking good!

 

Ok what is the over/under on if Cruz will bang it up before or after T2S? 8>) $100 on before. There is no way Cruz will wait to go radical until T2S

 

Now that's crazy

 

Hey Cruz, I know your truck is a 2016, but do you happen to know if the 2021 needs the drive shaft serviced and greased?

 

I believe so. If it has zerk fittings on the Ujoints then they should be greased regularly. Don't put too much grease in there otherwise it'll just get spit out all over the place when it starts to spin.

 

I said that I would do the Big 3 wire upgrade because I am upgrading to a 300 amp output alternator, but a couple weeks have gone by and I just barely figured things out. For the Tundra it’s actually a Big 4 wire upgrade. The purpose of the upgrade, to a larger gauge wire, is to support the increased amperage coming out of a high output aftermarket alternator. Hopefully, this will help others when they come down this path.

First, let’s start off with a simple diagram of how the OEM large gauge wires are connected.

1. Battery negative to chassis ground
2. Engine block to chassis ground
3. Alternator to battery positive via the fuse box
4. Engine block to battery negative

Replacing wires 1 and 2 is straightforward; remove and replace.

Wire 4 is encased in a wire loom with several other wires (there is also a pigtail connector on the alternator and the starter that is part of the wire loom). The easiest solution is to disconnect the OEM wire 4 from both ends (I zip tied the engine side and cut off the battery side where it enters the wire loom) and then run a new wire alongside the wire loom connecting the engine block to the battery negative.



Wire 3 is also encased in the same wire loom as wire 4. Do the same thing as wire 4 right? Kind of. I had to do a lot of research. This thread (Big 3/4 wire upgrade) helped out a lot but also confused me at the same time. So an explanation is in order.

The OEM alternator is rated at 150 amps. The alternator is wired via wire 3 to the fuse box where it connects to a 180 amp fuse, which it then connects to the battery and the rest of the truck’s electrical system. See image below.



When you have the key set to ACC, the truck gets its power from the battery and basically looks like this with the alternator out of the picture.



Once the engine is started the alternator provides power to the truck AND charges the battery, WHILE going through the 180 amp fuse.



If you have aftermarket accessories, then it may look like this.



In my situation I want to use an electric bucket water heater that is rated at 1500 watts, which, at max, could draw 167 amps. I tried using the heater with the OEM alternator but it did not work as it had to compete with the truck’s internal systems for the power. The 180 amp fuse did not blow because the OEM alternator could only pump out 150 amps.



If I upgrade to a 300 amp alternator and make no wiring changes, then I would easily blow the 180 amp fuse when I try to use the water heater.

What if I upgrade the wire between the fuse box and alternator?
Won’t make a difference, the fuse is the weakest link.

But the water heater is only drawing 167 amps and the fuse is 180, can’t it handle it?
No, because it's 167 amps + whatever the truck circuitry draws + whatever other accessories you’ve got connected to the battery.

The solution is to wire the alternator directly to the battery positive terminal, skipping the fuse box, as was shown in the thread (Big 3/4 wire upgrade). Makes sense and it’s really the only option. However, in the (Big 3/4 wire upgrade) they connected the 180 amp fuse directly to the battery positive AND left the Fuse box to Battery positive wire in place. Why? This confused me.



Both wires can supply current to the same spot except one goes through the fuse. Current takes the path of least resistance, which means current will go through 1 of the cables, unless they happen to have the exact same amount of resistance.

What worries me with this setup is an electrical short. Let’s say for example, current is going through the fuse, and someone hits your truck causing an electrical short somewhere that causes the 180A fuse to blow but since the other wire is in place current will reroute and continue to flow and now your truck is on fire.

At first, I assumed it was for voltage regulation where the ECU controls the alternator to increase or decrease output. For example, when it’s too hot in the engine compartment it is not good to continue charging the battery so the ECU would have the alternator reduce its output.

Thanks to @RainMan_PNW I was able to find this Toyota wiring diagram of the charging system and discovered the communication for voltage regulation takes place via the pigtail connection on the alternator, not through the large gauge wires. The diagram shows the alternator (aka generator) wired directly to the 180 amp fuse where the 5A ALT-S fuse and battery connect on the other end.



Some of you may recognize the ALT-S fuse. This is the fuse that can be replaced with a GM Diode to trick the alternator & ECU to increase output to properly charge an AGM battery.

At a very high level this is what (I believe) happens:
A. Voltage is detected
B. Voltage is passed through to the ECU
C. ECU takes into account voltage and temperature
D. ECU controls the alternator output via the Combination Meter

Let’s see what happens when you replace the ALT-S fuse with the GM Diode

A. Voltage is detected at (for example) 13.9 volts
B. The GM Diode has a little bit of resistance causing voltage to drop down to (for example) 13.2 volts
C. ECU deems the voltage too low to charge the OEM lead battery
D. ECU instructs alternator to increase output

The process repeats until voltage at point B reaches 13.9 volts but in actuality the voltage at point A is (for example) 14.5 volts, which is where AGM batteries need voltage to be in order to charge properly.

Now back to the wiring.
For wire 3 I ran a new wire alongside the wire loom to connect the alternator direct to battery positive.

I then cut the OEM wire 3 right where it enters the wire loom from the fuse box side and zip tied the other end (see earlier wire loom picture). I repurposed the Fuse box wire end by extending it and connecting it directly to battery positive. There is no need to upgrade this 2awg cable to a bigger wire gauge as it is only powering OEM systems.



To prevent the bypass of the 180A fuse I cut the Fuse box to Battery positive wire then covered it with shrink tubing and electrical tape as it is a live wire. Could probably take the fuse box apart and properly remove the wire but it's actually underneath the fuses/relays and I just didn't want to risk messing things up.



This configuration allows me to fuse protect the truck’s circuitry, charge the battery properly, and provide the increased power when needed. Enjoy.

 

Been awhile since I messed with it, and doubt it makes a difference for what your doing, but think we have a “dumb” alternator. If memory serves me correct voltage is regulated at the voltage regulator on/in the alternator, the alt-s supplies actual battery voltage for the regulator to control output. The alt-s diode mod shows a lower battery voltage to the regulator, and it increases output whatever amount the diode is reducing.

 

Hey Dave! So I did even more research on the alternator and it turns out you are correct in that we do not have smart alternators. The alternators are actually controlled via a combination of the onboard regulator (on the alternator) and ECU. I edited the writeup and removed "smart" from it to avoid confusion.

BTW... the FullSize Invasion registration opened up recently and it closed right away I checked the website last week and registration was not even open yet. Guessing you'll be at T2S instead?

 

Just pulled the trigger on a new set of Mickey Thompson Baja Pro XS... it hurts

 

Lean into that pain. Did you get 6 of ‘em?

 

Ooof. I bet those new 43s were expensive.

 

I want the new all terrain

 

Whaaaaaat! Those are nasty!

 

Bet they are real quiet on the street...

 

Interested to hear your thoughts. Seemed like a few Jeeps were running those when they came out and now haven't seen anything with them in awhile. Their sponsorship dollars must've run out so you'll be the first normal person I've seen run them

 

Did you just refer to @Cruzer as ‘normal’?!

 

Oh I’ve seen them on plenty of Jeeps, on YouTube. Been wanting to get a set of beadlocks to put these on for dedicated off road use, but no go. We’ll see how long these last.

 

Perfect! Don’t want to hear those Nitro 5.29 gears whining like a spoiled brat

 

Normal like a fox. A fox on oxy, without rest, and an axe to grind, in the desert.

 

Wolf Pack

 

Whats the smallest tire you ran with those 5:29s? Any issues/4:88s curious for planing 35s.

 

I had 37s a week after I bought the truck brand new. 5.29s and tuning the ECU for 5.29s made it feel like it was back to stock. I believe 4.88s and 35s have a similar effect.

 

Why no go on the beadlocks? I saw an ad on IG for 15% off racelines today