Drivetrain Weak Link ?

[Shoyrtt]

I am just about ready to begin my drivetrain work on my 85 Runner.    I am new to Toyotas so bear with me if my question seems obvious. My goal in the build up is to have a capable trail rig that will be street legal (not a daily driver) and reliable. I have a new set of 35 MTRs and will run a 4 inch lift. Now for the drivetrain that I have:

Dual Ultimate Crawler (21 spline) with Marlin's skid and t-case mounts

30 spline Longfields

5.29 Yukon R&P's Cryod by Longfield

Aussie Lockers front and rear.

Finally, (once I get everything in) I will probably order drive lines from Marlin or from High Angle directly.

So, here is the question, where is my drivetrain "weak link" (and is there anything I am missing)? My guess is my choice of lockers or maybe the 21 spline. I figured, both would be OK running 35s.

[seanc]

the next weak link will be the, steering, rear t-case uput. also stock thickness d-lines are pretty weak...

[Shoyrtt]

the next weak link will be the, steering, rear t-case uput. also stock thickness d-lines are pretty weak...

Rear t-case output? Why?

[Hyena]

Hubs will be the next week link in the front.  You should also upgrade the steering arm studs if you want beef.  The rear could be the axle shafts or the t-case output shaft.  but with 35's, you shouldn't worry too much about breaking with the drivetrain you have.

[FIREBALL]

That's gonna be a pretty bullet proof setup with that size tire.....unless you drive like a total ass. I'd say that if you were really honkin on it, the rear 21 spline INput shaft would be a possible weak link.
I'd disagree that the hubs would be a weak link. Unless your running something besides stock. Most of the aftermarket hubs for yotas are junk compared to the stock ones.
If you go with Marlin/High Angle drive shafts you really won't have to worry much there either unless you spend a lot of time using them as nerf bars.
You've spent some coin on this setup, but it should pay off well.

[Shoyrtt]

What about a Gusset? Offroad it will mostly be in the rocks (John Bull, Hammers, Calico).


Finally, should I expect any problems with the rear axle?

[Hyena]

gusset should help keep the axle straight.  I wouldn't worry about the rear.

[blackdiamond]

I would expect that unless you are a crazy driver or plan on jumping the truck (only reason for axle gusset in my opinion) then your front hubs are likely the weak link (good) and you should make sure you have the stock AISN hubs since they are stonger than Warn or Milemarker hubs.

I have heard that the R&P can be a weak link, I chose 4.88 Yukon gears for this reason (I heard that they were 60% stronger than the 5.29s, but I don't really know how true it really is.

The rear end should be fine as is and I have only heard good things about Aussie lockers.

I suspect that along with added strength, the cryo treatment makes things more brittle which might cause a more catestrophic failure IF you managed to break any of the parts.  Breaking the R&P may be more likely to take out the Aussie and breaking a Longfield (not likely at all) could take out the whole set.

As long as you drive with some sanity, I suspect you won't have any problems, but some people can break anything.   

I have 33 inch tires, detroit rear, trutrac front, single 4.70 case & 4.88 R&P and I want to upgrade to the 27 spline longs before I put a full locker in the front and then I will feel fairly bullet proof.

[Shoyrtt]

I would expect that unless you are a crazy driver or plan on jumping the truck (only reason for axle gusset in my opinion) then your front hubs are likely the weak link (good) and you should make sure you have the stock AISN hubs since they are stonger than Warn or Milemarker hubs.

The hubs seem to be the common theme. If I carry a spare AISN I should be OK.

Finally, I think I am going to pick up a twin stick to make turning a little easier and relieve some stress from the front axle. 8)

[blackdiamond]

The hubs seem to be the common theme. If I carry a spare AISN I should be OK.

Finally, I think I am going to pick up a twin stick to make turning a little easier and relieve some stress from the front axle. 8)

I would probably carry a spare Warn (cheaper) and then repair the AISN when I got home, just my 

[Shoyrtt]

the next weak link will be the, steering, rear t-case uput. also stock thickness d-lines are pretty weak...

I still don't understand why the rear output shaft is an issue. I have Marlin's duals (built by THE shop) which, I believe, resolves the output shaft. Here is a quote from Big Mike :

"For Marlin's Adapters, and I mean all of them, from the MC07 all the way up to the V8 Tundra MC09,
1: We use a Maximum service double-roller 32-ball bearing mainshaft bearing for the output shaft.
2: We use a complete NEW aftermarket Heat treated output shaft coupler."

Strong enough? 

[Shoyrtt]

I would probably carry a spare Warn (cheaper) and then repair the AISN when I got home, just my

You are right about a new AISN hub.   I was thinking about just picking up a used one for a trail spare.

[Hyena]

The rear outout shaft is still the 21 spline one.  Its not the bearings that you have to be careful with, it is the shaft itself.  the 23 spline shaft is stronger.  But you shouldn't worry about it breaking one.

[Ramrod]

I would say that the setup you described would be pretty damn bullet proof, espescially with only 35's.  my truck is running 37's with genuin gear 5:29's,21spln mco7,aussie front,detroit rear,marlin skid,27spliine longfield set and skys hysteer and axle truss.  I have put 7,000 miles on it since late june and wheeled the con 3 times, fordyce once and the highlakes and some other trails.  I have not broken anything yet and nothing seems like it's having problems.  i drive this truck around 50 miles a day

[Ramrod]

also in no way do I go easy on my truck. ask hyena or fireball

[S-10 Stewy]

Sweet set up!!!!    You have some kick butt parts there .... should hold up good.  As far as the front hubs: stay "OFF" the gas when the tires are in the air and you will be fine.  They hate that "shock load" thing that we love to do to them. 

That rear output shaft .... I agree with everybody else.  The rear axle .... well .... mine has held up to my Chevy 350 and 36 inch TSL's for years now.    You have an awesome comb for running gear shoyrtt.  Have fun and see you on the trail. 8)


Stewy

[Shoyrtt]

Thanks for the help.   I figured I was OK running a 4cyl with a 21 spline. My buddy's Runner runs a 350 and dual cases. The install was done by the previous owner several years ago and he hasn't had any problems (Moab, Con, Hammers). Marlin makes nice stuff.



Now if it would just stop raining here in So-Cal, I might start the install. Sounds like a new thread.

[Hyena]

also in no way do I go easy on my truck. ask hyena or fireball

He hammers it, his truck keeps asking for more.

[dj]

I have about a 400 hp 350 and 21 spline duals, been giong for about 2 years I broke the front iput shaft back in july acting absolutely stupid (climbing a veritcal edge at full throttle in H-H4 the truck was leaving the ground ad grabbing traction when it landed, the duals were in a 4cyl since about 2000 before I bought them. I don't think I would worry about it if I were you. unless you plan on upgrading to massive tires later. Sounds like you will have a kick but wheeler when you are done.