GX470 Unsprung weight grenading rear diff

F350joe

Well-known member
Is it for sure tho? The guy who started GXOR and was the one of the first people modding GXs for off road in the USA and was ordering parts for Prados when there wasnt a market for anything yet has been in the group and observed the most GX convos than any living person and his famous line is "Its not a matter of if the rear diff will grenade, its a matter of when". He genuinely believes that anybody who takes thier rig off road will eventually blow their 8" diff in a GX470...
Offroading breaks stuff, “overlanding” not so much. There should be a difference to how they are outfitted but that is not usually the case. The result is a rig that does both okay but neither very well. Over weight and top heavy is not good for the drivetrain if you are tackling obstacles. If your goal is to seek out and tackle obstacles, plan on a rear end or just keep the one you have tight. If you are into remote camping and just need the 4x4 to get out, find the path/line of least resistance and you should be fine. IMO.
 

tacollie

Land traveler
I'm still skeptical. I think you will have front end problems before you blow the rear end.

Maybe people are trying to get to much suspension travel out of the rear end and it's putting stress on the diff. That's pure speculation.
 

Tex68w

Beach Bum
Run what you've got, if/when that 8" rear end blows up then you have an excuse to upgrade to the 8.2".
 

bkg

Explorer
Run what you've got, if/when that 8" rear end blows up then you have an excuse to upgrade to the 8.2".
Doesn't it have the 8.4" already? I thought all v8's from 00+ got the "8.4" (i know it's not really 8.4, but it's the common vernacular for it....)
 

direwolf82

Member
Sure, just like folks told me it was only a matter of time when my 2-pinion front diff of my 100-series will explode at any given time. Driving a Ford will leave me stranded. None of this has happened.
It usually the same folk who wonder how I roam the desert without a RTT, rotopax, and a custom drawer system.

Now, can it? Of course. Then again, lots of things can happen. If you’re afraid of the “what if’s”, just stay home.
Yes!! How many times have I been told that my 1st generation closed knuckle d60 was going to explode if I put a a 350 in the Jeep, or if I went to 38" tires and neither has happened so far and I have accidentally shock loaded the front end pretty hard.
I tend not to listen to anyone who says "this is guaranteed to happen", I took my 4runner up things that the locals told me no way in heck can you get up that and you'll roll or break stuff if you try. Funny that I've driven up, down, back up and back down with no issues. It all depends on your skill level and who is spotting for you.
Although honestly it kind of sounds to me like the op is looking for an excuse to upgrade, you want to minimize worry about it again? Stick a full floater d70 or 80 in the rear, probably the closest you'll get to unbreakable realistically since you probably can't exactly fit Rockwell's under there.
I would think that cv's would go long before the rear end and I know I have seen more driveshafts twisted up then blown rears honestly and that's between drag racing and offroading.
I watched a video one time, guy blew both cv's bouncing up a hill but the rear end is what actually got him off the trail because it was fine after that abuse.
No such thing as an unbreakable truck, there are such things as more careful drivers though. As someone mentioned earlier pick the right line, start trying the obstacle in super creepy slow motion, add momentum only if needed, enjoy being at the top of the hill or whatever so you can tow out people with a heavy right foot and snapped parts.
I've seen a d44 live with 40" tires in the rocks before, that guy knew throttle control and wheel placement.

Sent from my XT1650 using Tapatalk
 
Run what you've got, if/when that 8" rear end blows up then you have an excuse to upgrade to the 8.2".
My issue with this (which is what a lot people say) is that unless youre out there with someone whow ill tow you out for free, itll cost more money to get your car to a shop then the upgrade itself... especially since you can sell a functioning 8" to offset a decent percent of the 8.2" - Thats why Im trying to evaluate the actual risk of this. Every community other than GX specific seem to think the 8" blowing is insane to be super skeptical about without user error, but the GX community is convinced that 8" is too weak for the weight of the GX + the v8 tq. We just had another diff blown on a 33s with almost no extra weight and claims very little bounce. In the last 2-3 months Id say there was at least a dozen or more people in GXOR with blown diffs, most of them didnt seem to be completely egregious user error
 

Tex68w

Beach Bum
I have no GX470 experience nor do I run around with anyone who owns one so I can't say whether or not the 8" rear-end issue is a valid concern or not. I can say that I hear about it quite often on the forums and over on GXOR so there has to be some truth to it. I would run what you've got until it fails and then upgrade, but if you're planning some huge cross country, multi-week trip with lots of remote heavy off-roading then you might want to consider a proactive upgrade rather than being reactionary.
 
I have no GX470 experience nor do I run around with anyone who owns one so I can't say whether or not the 8" rear-end issue is a valid concern or not. I can say that I hear about it quite often on the forums and over on GXOR so there has to be some truth to it. I would run what you've got until it fails and then upgrade, but if you're planning some huge cross country, multi-week trip with lots of remote heavy off-roading then you might want to consider a proactive upgrade rather than being reactionary.
Agreed. I feel like GXOR has it a little blown out of proportion which was why I wanted to get an opinion here. Polar opposite viewpoints in the end so hard to know what to think. Expo seems to think as you saw that its kidna odd that anyone would be blowing their 8" without insanely heavy loads or user error. GXOR seems to think that its not IF but WHEN you will break your 8" if you are doing any legit off-roading.
 

locrwln

Expedition Leader
It’s a big enough deal that every platform (GX, 4Runner, FJ) of that era talks about stripping the 8” ring gear teeth on their forums. Most of the big/well known Toyota driveline shops offer an upgraded rear axle (8.2, 9.5, D60) option for that platform, so there must be something to the phenomenon.

Toyota created the 8.2“ for a reason. The ring gear size barely increased in actual measurements, but apparently, the third member casting is much beefier to prevent the ring gear deflection that causes/contributes to the problem in the 8” differential. Adding a stronger (ARB and solid pinion spacer) differential doesn’t prevent the breakage either according to those who have upgraded and still stripped the teeth.

Jack
 
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