Topic: Gear Drive vs Chain Drive Transfer Cases - Which is Stronger and More Reliable?

[Timmah]

Hey Guys,  I recently had a failure of my 4.7 gear driven case on the Rubicon trail on Cadillac Hill.  I was able to luckily drive out using my 2.28 case and I was able to drive home in 2wd.  A friend of mine with a lot of experience in the industry told me gear driven cases fail much more frequently than chain driven cases.  I'm considering ditching my gear driven case set-up and going with a Northwest Fab dual case set-up.  If I go that route, I have to switch to a R-Series transmission, and either get a full replacement bell housing or an adapter that will bolt to my 22RE engine.  It will be a fairly costly modification. 

I'd like to hear more opinions on the subject of the strength and reliability of gear driven cases vs chain driven cases.   I'd really like to avoid a failure like I had in the future.  I bought my 85 4runner already built.  The transfer case always made noise under deceleration in 2wd, and I just assumed that was normal, but maybe it isn't.  I'm now wondering if I was getting advanced warning that the transfer case had an issue or was what I was hearing is normal for these cases?  At the end of day, the day before the case had the failure, there was clearly a difference in the sound of the transfer case that both I and my buddy that was riding with me could notice, but there wasn't really anything we could do about it at that point since we were deep into the trail at Rubicon Springs.  I did check the gear oil level, and it was full.

So, please let me know your thoughts on this subject.  Thanks!

[Gnarly4X]

Gears will always be stronger.

Gnarls.

[Timmah [OP]]

Gears will always be stronger.

Gnarls.

Thanks for sharing your opinion.  The way I came to this discussion is someone I know with a lot of Rock Crawling experience and experience in the Toyota industry with rebuilding transfer cases, transmissions, engines, etc, has told me those 4.7 cases fail a lot.  It's not a matter of IF it will break, but WHEN it will break.

[Gnarly4X]

Hello Timmah,

There are many “experts” out there.

If you know a person with specific experience, as you mentioned, and he has proof of experience with a specific Toyota part, then I’d accept his knowledge and opinion.

When I had my W56 transmission repaired, the very reputable tranny shop owner was very experienced and answered all my questions and gave me his 20+ years of experience rebuilding that transmission.

He told me what synchros he only installs and why. He told me what clutch discs he installed and why.  I believed him.

I do research as a hobby and I read books and watch 100s of videos and posts in forums, YouTube, and receive 100s of emails a week from multiple high-level sources.
What I know after about 50 years of constant research on many subjects, there are different opinions and levels of knowledge.
It is not always easy to decide what is factual based upon some level of proof and well-supported data and what is Bravo Sierra.

Someone at Marlin Crawler should be able to provide a valid expert opinion on your original question.

By the way, the incident of component failure on a rockcrawler has more to do with the driver, lack of maintenance, and improper application selection than an inherent design failure by the Toyota engineers.

That’s just my worthless opinion after 20 years of serious rockcrawling and owning 14 Toyota vehicles.

Gnarls.

[toyodaaddict]

"The transfer case always made noise under deceleration in 2wd,"
This is a common symptom when lifting and or running dual cases  in a toyota without a CV drive shaft. To correct this, run a CV shaft with the pinion 2* under the slop of the shaft. Something to look into if this noise on decel persists after the repair.

Marlin's competition 4.7 is the best 4.7 gear set available, in my opinion. 2.28×2.28 duals are probably less likely to fail if you don't need the super low 4.7s. 2.28×2.28 is still pretty low geared.

  "It's not a matter of IF it will break, but WHEN it will break." Im not buying this, at least not with a 22re, 37's and some common sense. Power and 40+ tires, probably true.

I wouldn't give up on the RF1A cases but If you actually have built your rig beyond what they can handle you probably want to get away from Toyota cases all together.   

[Timmah [OP]]

Hello Timmah,

There are many “experts” out there.

If you know a person with specific experience, as you mentioned, and he has proof of experience with a specific Toyota part, then I’d accept his knowledge and opinion.

When I had my W56 transmission repaired, the very reputable tranny shop owner was very experienced and answered all my questions and gave me his 20+ years of experience rebuilding that transmission.

He told me what synchros he only installs and why. He told me what clutch discs he installed and why.  I believed him.

I do research as a hobby and I read books and watch 100s of videos and posts in forums, YouTube, and receive 100s of emails a week from multiple high-level sources.
What I know after about 50 years of constant research on many subjects, there are different opinions and levels of knowledge.
It is not always easy to decide what is factual based upon some level of proof and well-supported data and what is Bravo Sierra.

Someone at Marlin Crawler should be able to provide a valid expert opinion on your original question.

By the way, the incident of component failure on a rockcrawler has more to do with the driver, lack of maintenance, and improper application selection than an inherent design failure by the Toyota engineers.

That’s just my worthless opinion after 20 years of serious rockcrawling and owning 14 Toyota vehicles.

Gnarls.

Thank you for sharing your opinion on this.  I found it helpful.

[Timmah [OP]]

"The transfer case always made noise under deceleration in 2wd,"
This is a common symptom when lifting and or running dual cases  in a toyota without a CV drive shaft. To correct this, run a CV shaft with the pinion 2* under the slop of the shaft. Something to look into if this noise on decel persists after the repair.

Marlin's competition 4.7 is the best 4.7 gear set available, in my opinion. 2.28×2.28 duals are probably less likely to fail if you don't need the super low 4.7s. 2.28×2.28 is still pretty low geared.

  "It's not a matter of IF it will break, but WHEN it will break." Im not buying this, at least not with a 22re, 37's and some common sense. Power and 40+ tires, probably true.

I wouldn't give up on the RF1A cases but If you actually have built your rig beyond what they can handle you probably want to get away from Toyota cases all together.   

Yeah, I'm just running a 22RE engine and I take it easy when wheeling.  I do like having the 4.7 case so I can drive nice slow and controlled through harder obstacles. 

It will interesting to see if the deceleration noise disappears after I get it rebuilt and reinstalled.  Thanks for sharing your knowledge on this subject.

[blackdiamond]

If you have a 22RE, drive smart, and Marlin Crawler gears you should not expect to ever have issues.  Unless Cadillac Hill is a lot different than when I did it, it was the straw that broke the camel’s back it the gears already had an issue.

[cbeers]

I agree in that it sounds like you already had issues with your case.

https://www.marlincrawler.com/java/gearvschain.html

CB