Toyota FJ Cruiser Forum banner

Transfer Case Overview, Aftermarket Options, Gearing, and Drive Ratios

27K views 122 replies 28 participants last post by  football751 
#1 · (Edited)
#5 ·
Very nice write up.
Any chance you can make an amendment for the interaction and final drive ratios with the manual transmission?
 
#7 ·
I read it over a couple times. Not knowing anything about doing this I was wondering:

1) Does a CT swap effect 4HI or stuff like ATRAC at all?

2) At what point in someone's build does doing a CT swap make the most sense? I noticed you referenced 4.88 gear axles so I am guessing you'd want to do that first, guess I am wondering what the logical order of things is.
 
#9 ·
Thanks for the info. I read over what you posted a couple times and if I were going to swap out my TC, the budbuilt + lefty combo looks like what I'd want. Makes sense to me to do a re-gear to 4.88's first and fit 35's.

Are you aware of any TC setups incorporate something similar to a 2lo? Teraflex makes this one that works with the JK's rubicon TC. I am not aware of anything similar for yota's.



Here is their description of it's benefits:

The 2Low kit increases trail turning ability by allowing tighter turns on narrow switchbacks, and eliminates most front end steering bind associated with 4WD. The 2Low kit is a completely internal modification and does not require any other modifications to the transfer case housing or components. Installation can be done with the front-half of the transfer case remaining in the vehicle. The 2Low retains the use of all factory low-range options – such as; ESP disabling, electronic swaybar disconnect, and locker engage & disengagement. In the 2Low position the 4WD dash light will illuminate indicating you are in a low range gear. The new shift pattern is: 2H > 4H > N > 2L > 4L Fits Rubicon Model JK Wranglers only (241-OR transfer case)
 
#10 ·
Are you aware of any TC setups incorporate something similar to a 2lo?
You can do that with a Lefty, just order it with twin sticks. You'll have one stick for high range - low range, and another for 2WD - 4WD, thus enabling 2-low. I have twin sticks on my FJ40, and have yet to use the 2-low option though - the only reason I did it on that truck was to get better mechanical lever advantage on that particular (Orion) transfer case. My Lefty is a single stick and I have never missed it there either. YMMV.
 
#13 ·
Excellent research, The only thing I would add is a comparrison of load carrying capability of chain Vs Gear. A chain ends up being wider than a gear for a given amount of force transmission. The reason is that if you compare a gear's section modulus to it's bending moment arm length you will find you need more chain link shear area to carry the stress, which equates to width for chain or strands. Chain will also have more pivoting surface area, so friction/heat will be more prevalent. Chain efficiency is less than gearing! For the same gear ratio, any given chain will require a larger OD & center distance, therefore as you mentioned makinig the case a bit bigger.

86XX/10XX/11XX series shaft materials require significant amounts of carbon to harden into the high RC-50's, becasue they are cheap. Heat Treat is very critical, so cracking can ocurr during the HT process. The 86XX series is preffered material in the industry for elevated hardness with improved ductility when comparring its cost to benefit ratio. The better choice as you mentioned are the 41/43XX series steel alloys. The chromium steels have significantly improved strength even without Q&T, that equtes to better fatique properties all around. You pay for what you get!
 
#14 ·
If nothing else at least it’s a nice departure from the, will this 16” wheel fit the FJ? Will this tire rub the body mount? What is that clunk I feel when stopping at a stop light? What to spend $xxxx.xx amount of money on (even though there is a thread which tells you exactly what to spend the first $2000.00 on)? FJ vs. Jeep (and why of course the FJ is always 300 times better)?, Will you keep your FJ forever?, How’d your FJ get its name?, 3” vs. 6” lift?, what did you do to your FJ today?, etc. If you haven’t caught my drift by now the majority of the threads on this forum are chit chat type stuff, redundant, or simply add little value in any way (except as another thread to appear in the search function and keep advertising revenue rolling in for the forum owners). It is depressing when this forums is advertised as the LARGEST FJ CRUISER FORUM and compare the lack of technical discussion on this forum to other offroad forums (Mud, Pirate, RST, GL4x4, MC, and many others) and significantly less than other automotive forums (hoda-tech, rennlist, 6speedonline, etc). There are maybe a few handful of threads posted in here yearly that I would consider “valuable resources” for FJ owners. The majority of those were started by people who rarely post here anymore (bellydoc, sbechtold, Sean K., MTBcoach, NCFJ, etc.) and others who still contribute some worthwhile discussion points (1911, Wikid, Layonn, Jeshua, FJinCO, MIGZ, etc.). Basically this is my last effort at trying to stimulate some new discussion on this forum.
Thanks FJNewb! Bring on the Tech. I can't remember the last time I was even in the general discussion Forum. We need more of this type of discussion.
 
#16 ·
Marlin and Inchworm also offer crawlboxes (dual cases) for the FJ or a case which will mount to the OEM FJ transfer case. Your gas tank would need to be modified to get the Marlin & Inchworm products to fit.
I think that this important to note. If I didn't get such a good deal on my lefty (free) I would have added a crawlbox to my stock case. Mainly for having a middle gear ratio. Often the 4.7 is too low and the 1:1 is to high. Having that 2.56 option would be great.

One of these days I will open up my t-case and find out what gears I have in there and upgrade if needed and add a 2.28 crawlbox in front of the 4.7.

When all said and done I will be looking at a crawl ratio around 236:1 but still have plenty of flexibility.

I should probably get around to chopping off my crossmember and re-routing my exhaust too..... Damn work that pays for it all keeps getting in the way.
 
#20 ·
Wouldn't your final ratio be 218:1? (4.88 Axles * 2.28 crawlbox * 4.7 lefty * 4.17 Tranny = 218).
I did the calc based on 5.29 gears. I still have not narrowed down exactly what axle/gear/locker combo I will end up with. It will most likely be larger than 4.88


I like the spread of 1:1, 2.x:1, and 4.7:1 (~10:1). Although I don't know how useful combination the 2.x:1 & 4.7:1 ratio is. That large of a crawl ratio will surely reduce shock loading of your axles and drivetrain (which seems to be the root cause of most breakage I've seen). However, it will put out more torque than your brakes can stop. I know Nick used his 10:1 ratio on part of the rock garden at Jamboree, but I guess that was the first time he got some use out of it. For the uber technical trails there might be value, but for the majority the 4.7 ratio seemed solid for the techinical stuff.
In Colorado we have plenty of rocks, dual cases with this combo are pretty common. My initial goal is to be able to have the ability to swap between 2.28 and 4.7 for most stuff. 10:1 once in awhile on big obstacles.

Has anyone put a triple case in an FJC yet?:thinkerg:



Good choice on putting the crawlbox in front of the Lefty. That way the Lefty case is only seeing half the torque load on the input shaft, compared to if you had them reversed...less chance of overstressing and breaking crap.
Yep, that's the main reason for that order. I could probably find a junkyard case for fairly cheap and either upgrade the gears or leave it stock and see how it goes.

As you have probably seen, Wyatt (AWSUMDC) from RST has a plan to add dual cases to his new V8 4runner with no gas tank modification..... I am waiting patiently to see what he has in mind.


Now how much gas tank modification for a triple case.....
 
#22 ·
I got my case in Feb of 2010. The previous owner bought his FJC with already installed lefty a few months prior, before that, not sure when the lefty was originally installed. Unless they failed once before and upgraded, I am guessing I have the original TG gears.
 
#24 ·
Ah, ditching the IFS I see?
shhh.... It is in the plans (was going to wait a few more years, but those RST guys are starting to get to me). Most mods are on hold until I can get the money together to get it done.

Simple. Get this and do a 4 link rear...no issues with the gastank then.
Not out of the question, but leaving the cargo area alone is preferred

It'd honestly be easier to fit a Stak + crawlbox resulting in 6 speeds than triple cases (7 speeds). You could even keep the gas tank and I'm sure one less ratio isn't going to be a deal breaker. Most competition vehicles don't normally have more than 4 ratios. Only vehicles that I'm familar with that sometimes have more are the mini trucks, but more so due of the lack HP & torque they put out compared to modern vehicles.
Honestly, a triple case is not for me, but It would be cool to see it done, but not for me. I have been around a few mini trucks with triples. Very cool stuff. But yes, a better fit for a 22re than a 1GRFE.
 
#26 ·
Not that many people have or want low gear transfer cases for the FJ cruiser. 90% who do have a lefty.

I suspect that in a few years, when the used FJ market gets cheaper, more hardcore offroaders will jump in the frey and up the anty for low gearing and such.

Definately saw that happen with the 80 series LC.
 
#28 ·
The whole point of posting this was so other (new forum members and simply those that are gear heads) could learn and have a discussion, not neccessarily for only those who are looking to buy a case.

So lets get some new discussion going in this thread....kick it off Ryan.
Sorry, I just saw this.

A few questions you may have covered already; however, can you explain why AT implicitly needs less gear down for similar results on an MT?

Also, we all know of several vehicles that have blown their transfer cases; however, I have also seen a few that have blown the front or rear input shafts (not FJCs) instead of the TC. I think it might be worthwhile to discuss options on shafts such as Chromaly/spline count and considerations for the various cases you mentioned.

I like the conversation we had on my thread about the flange issue on the dana. It doesn't matter how strong the gears, the shaft or the TC is if your connection points are weak.

BTW did you see those sexy shafts Belly doc bought?
 
#33 ·
You can also get torque converters that are set up to lock up at a lower RPM than the standard TC that comes in the trans stock. Using this type of TC along with modified shift patterns within the trans allows the end user to set up the type of trans to best fit the application.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top