Topic: 4:70 reliability myth?

[hilux-1983]

I got a question on what I kinda overheard some dude saying while I was at KOH some years ago. It's stuck in my mind and I've never inquired if it was true or not. He said "the 4:70 gear,bearing set will blow apart if constantly used in 2nd, 3rd, 4th and 5th gears on the trail." His theory was that the 4:70 is spinning so much faster because of the reduction, added friction due to that faster spinning, extra stress on the bearings, etc... He went on and on about it. Every time I shift into low I can hear his voice. I have a singe t-case with the 4:70 and am constantly shifting from 1st thru 4th on the trail. I haven't had any issues since I installed it a few years ago. Gear oil is clean, no noises and so on...  It's my DD and trail rig. Does this guy's theory hold any water?

[twistedtoy92]

As long as you have the case filled with good clean quality oil you will be just fine! 

[Goldrush]

I have the exact same set up, just a single 4.70 case behind my W56-C and I use 4th/5th gear a lot up here with the local trails. It does get a little noisy when in 5th but that's because i rev it a bit high. My truck is also a DD.  You should be fine.

[TimberlineBryce]

It doesnt do any good to worry about it so just drive it and have fun!

[BigMike]

If you would like to set aside all doubt before you can finish reading this sentence, then let me tell you that the input bearing used for the 4.70:1 gear set is the same as a W56 main shaft bearing.

Maybe the worst case would be for the input pocket bearing which is the smallest bearing and experiences the greatest difference in shaft speeds. However they are so reliable that I even built my own transfer case back in 2004 with a used pocket bearing.

If you have the proper gear oil at the proper level then you have absolutely nothing to worry about. Marlin invented the 4.70:1 ratio and gear set back in 1996. I can assure over the 17 years of sales we have never experienced what you overheard.

BigMike

[hilux-1983 [OP]]

I figured those would be the most logical answers I would get. Thanks everyone. 

[mannysouza]

I have heard that using 5th gear with 4.7 low can cause transmission failure. Due to being the weakest gear and the torque associated with low.

[Mrsmithyx1]

When I get a 4:70 I'll show you jow to blow it up

[OOPS]

In 1998 I bought a 4.70 gear drive to put into my 1990 Toyota ex-cab. This truck saw lots of street miles in the beginning and has seen many, many hard trail (Con, 4-dice, Moab, Dusy and The Hammers. Guess what, I am still running the same case and gears. It was gone through by Rocky at Marlins shop a couple years ago and he replaced a couple of bearings and some shifter rings. The person that owns JP Eater told me it would blow up in a year, still waiting.

[fordh8r]

Don't forget...while the t-case is in High range for street driving, those 4.7 low gears are still spinning and at proabably higher speeds. Granted, they aren't under the same load as when shifted into Low range. But if speed is the factor you're worried about then you should worry more about your daily driving than trail riding.

[H8PVMNT]

Yeah I bought a 4.7 case way back when from Marlin, I think it was the second batch of 4.7 gears they had, maybe in like 2000.  I have a TON of trail miles on it and no problems at all.  That guy is smokin' crack.

[Mrsmithyx1]

That's some good info guys, I was just messin with HILUX-1983 cuz we have wheel together and I'm a little ruff at times (not happy till it's broken

[Prismo]

I have almost 300,000 miles on my set. I would say they probably last OK.

[stubbysr5]

s

 Yep. Must have been a cheep dewd talkin.

[87Fontana]

I had a 4.7 single t-case in my first 4Runner.  It never gave me any problems and my tranny held up fine.