2011 GX460 - TEMP RWD with Front Driveshaft Removal?

[malomalo]

Hey all,

I posted this question embedded in a wall of text in a reply yesterday, so just going to start a new thread to see about possibilities here. I did find an old thread on the 80-series forum, but figured I'd see if there was any experience amongst the GX460 crowd, and whether the same advice translates. Thread found here: Front driveshaft removal instr. Please

Question: If there are issues with the front driveshaft and/or transfer case section that rotates the front driveshaft, is it safe to unbolt, lock center diff, and drive as a RWD?

A tech at the transmission shop I've been working with pulled the front driveshaft and locked the center diff to see if my symptoms of low gear shudder would go away, and they apparently completely cleared after he did this. I've read that it's possible and relatively safe, but there seems to be a lot of emphasis on being sure the center differential is locked. Anyone have any experience with this?

Thanks!

 

[r2m]

Never heard of it being done in an "All-Wheel-Drive" system only rear wheel with a locking front.
There's a lot of wizardry that goes on in all wheel drive systems, like delegating power/torque to any one of the four wheels in a flash of a second, stability control and who knows what-all else!
If I were to do it, it'd be for a few trips around the block or whatever it takes to try to duplicate your issues, then get back to working order again.
Just my .02¢.

 

[JasonW]

The transfer case is just a torsen diff that can be locked. There are several that have been able to drive home with a broken CV with the center diff locked.
I would be surprised if it would move at all without the front driveshaft with the transfer case unlocked.

 

[Roody]

Great question. Some of us are interested in this so we can run RWD on the street for better MPG (and RWD) fun and kick it into AWD/4WD off-road. Know the 80-Series guys have done this and the FJ transfer case swap has become a thing with the 4th gen 4Runner guys. Would be a fun party trick for the GX460s down the road.

 

[Rednexus]

If it were my rig - I'd drive it without thinking twice about it, but probably try to get the actual issue fixed quickly.

 

[Acrad]

IMO: To original OP question…perhaps as a test…not as a long term option or solution with the stock hardware.

Side note… saw some 100 series discussion elsewhere on topic years back and fuel savings if one does it are negligible.. caused other issues I can’t recall at the moment as well

 

[r2m]

IMO: To original OP question…perhaps as a test…not as a long term option or solution with the stock hardware.

Side note… saw some 100 series discussion elsewhere on topic years back and fuel savings if one does it are negligible.. caused other issues I can’t recall at the moment as well

I can easily see it throwing codes if it can't detect any torque on either of the front tires. Am I wrong?

 

[JasonW]

I can easily see it throwing codes if it can't detect any torque on either of the front tires. Am I wrong?

It’s only reading off the wheel speed sensors.

 

[malomalo]

Thanks for the feedback!

I did end up driving the vehicle back home from the shop, ~5 miles with a mix of highway and neighborhoods, and it was acting fine. Shifting was smooth, no strange vibrations, felt slightly more "nimble" on the road without 4wd.

Got me thinking maybe my issue was actually the front DS--ungreased bearings or worn joints... but then yesterday I drove it around the neighborhood a bit and started getting a fairly consistent shudder again. Wasn't the same issue as before though, more of a mild shuddering between 20-30mph; not like the previous issue that felt like severe shudder/slipping between 1st and 2nd gear.

So I'm not quite sure what to do next. I greased the zerks on the rear DS and did a drain and fill on the Transfer Case fluids (went with 75W Ravenol) just to see if that was the issue, and drove around afterwards with little change in symptoms.

Perhaps both of my DS are going due to poor upkeep, and the rear just happens to be in slightly better shape than the front, so my initial issues decreased after pulling the front out. Or maybe these vehicles just don't like being put into RWD only and it's adding undue strain to the rear DS now.

Hard to say at this point, but I may try to pull a front and rear DS from a slightly newer GX wreck in the area since they seem to be the same from the 470s til the latest year 460s, and swap them out to see if that changes anything. Other than that, I guess I'd be looking at trying to find a rebuild/reman transfer case.. so I'll exhaust everything else before jumping into that.

Open to any tips or suggestions on things to check or try!

 

[malomalo]

Dropping in with an update:

Ended up purchasing a used front DS from a '17 with fairly low miles for about $100 (ends up being somewhat of a wash if I just replaced u-joints and had them pressed locally) and installed it. Vehicle went back to having the same initial issue of 2nd gear shuddering/clunking violently at random times.

So I decided to run a similar test by taking out the rear DS, locking the center diff, and running it FWD. When I did this the vehicle drove exceptionally better. No more shuddering, no violent gear slip. Still felt slight vibration around 25-35 mph, but at this point that could be due to needing a wheel balance and rotate. The FWD setup does feel a little under-powered though; felt like it took a lot more to get moving from a stop and the low range acceleration was lackluster.

Next I had bought some Moog u-joints (stronger w/o the zerk) and got them pressed into the removed DS at a local shop. I started to attempt this myself, but don't have the right tools to do it effectively and didn't want to beat it to death trying to get the old ones out.

Today, I re-installed the rear DS with the new u-joints. Test drive around the block and it's doing the same thing it originally did with the 2nd gear shudder. So now I've got a new/used front DS that seemingly drove well in FWD only. Brand new u-joints on my old rear DS. But when they're all back together I'm back in the same boat.

I don't really know where to go from here. Was hoping the u-joints would be the fix. I know the slip yokes need to be aligned perfectly to maintain balance, but does that also hold true for the position that the DS is mounted to the TC and Diff plates? Maybe I'm really grasping here, but should I try doing a 180 rotation to see if anything changes? Could bad carrier bearings or pinions on the rear DS be the issue?

I feel like it's probably just the transfer case at this point, but I want to rule out everything else I can. I might try to find a salvage transfer case and have the transmission shop that did my rebuild install it.

 

[JasonW]

How many miles are on your rig? You state a 2nd gear shudder? Does it only do it at a certain RPM and/or MPH? Tried using the 2nd start feature? Possible torque converter issue?
I’d get the tires 100% balanced before throwing hard parts at it.

 

[malomalo]

How many miles are on your rig? You state a 2nd gear shudder? Does it only do it at a certain RPM and/or MPH? Tried using the 2nd start feature? Possible torque converter issue?
I’d get the tires 100% balanced before throwing hard parts at it.

166k, the shudder isn't consistent so it's been hard to narrow down exact circumstances, but it tends to happen more or less when driving slowly through neighborhoods with a lot of stop and go. Speed up, slow down, stop, speed up -- then it shudders between 1st and 2nd, is the typical scenario.

Torque Converter was replaced, and then replaced again by the transmission shop under warranty as a hail mary because they couldn't determine what was wrong.

Haven't tried using 2nd start, not very familiar with that, but I can do some googling and see about it.

Agree on the tire balance, at least for the 25-35mph vibes. The other issue of the hard shuddering is pretty distinctively something happening within the drive train--either transfer case or rear diff from the way it feels.

 

[r2m]

166k, the shudder isn't consistent so it's been hard to narrow down exact circumstances, but it tends to happen more or less when driving slowly through neighborhoods with a lot of stop and go. Speed up, slow down, stop, speed up -- then it shudders between 1st and 2nd, is the typical scenario.

Torque Converter was replaced, and then replaced again by the transmission shop under warranty as a hail mary because they couldn't determine what was wrong.

Haven't tried using 2nd start, not very familiar with that, but I can do some googling and see about it.

Agree on the tire balance, at least for the 25-35mph vibes. The other issue of the hard shuddering is pretty distinctively something happening within the drive train--either transfer case or rear diff from the way it feels.

2nd start is just as it sounds. Instead of pulling from a dead start in 1st gear, you start out in 2nd gear. After you get going, the rest of the shifting and everything else is normal.
The purpose is when you're on a very slick surface, e.g. snow, ice, etc. you will not get the wheel spin as you would get in 1st gear, thus providing a safer more linear transition of power from rubber to the road (or ice, or...)
In general, it reduces torque applied to the driving wheels when starting from a dead stop.

 

[malomalo]

Thanks for the info @r2m!

@Acrad shot in the dark, but you happen to see any specifics on driveshaft alignment in the FSM or can point me in that direction? The mounting points have a center with specific notches and I'm inclined to think those notches need to be aligned in some way between each side of where the driveshaft bolts onto the Front Diff/Transfer Case and Transfer Case/Rear Diff.

 

[Acrad]

Just see this

 

[malomalo]

Thanks @Acrad! I guess I need to find out what these matchmarks look like, unless that's just referring to matchmarks that would have been made when they were initially removed.. in which case I may be screwed

The only ones I've seen are on the center of the diff/transfer case flange and it's a "notch" on the center ring that sits inside the yoke flange when bolted up.

 

[malomalo]

Decided to record shifting between Neutral and Drive from the Driveshaft perspective. I don't know what to expect here, but this doesn't seem right. And Driveshaft alignment shouldn't impact this right? You'd see that more in vibes while driving I'm assuming.

Perhaps the TC is shot?

 

[Rednexus]

Can you put your hand on the TC and see if the click is coming from inside it? You shoudl be able to "feel" the source of the click (please chock the wheels and take all precautions not to get ran over doing this!).

Also - forget if I asked this before, but have you drained the TC fluid to look for signs of failure (i.e., metal shavings)? That would be a dead ringer for a shot TC and should just take a few minutes to complete.

Brand new TC is only $3K from Lexus (pretty reasonable IMO for a totally new OEM unit).

Genuine Lexus GX460 Transfer Case

Shop wholesale-priced OEM Lexus GX460 Transfer Cases at LexusPartsNow.com. All fit 2010-2023 Lexus GX460 and more.

www.lexuspartsnow.com

 

[malomalo]

Can you put your hand on the TC and see if the click is coming from inside it? You shoudl be able to "feel" the source of the click (please chock the wheels and take all precautions not to get ran over doing this!).

Also - forget if I asked this before, but have you drained the TC fluid to look for signs of failure (i.e., metal shavings)? That would be a dead ringer for a shot TC and should just take a few minutes to complete.

Brand new TC is only $3K from Lexus (pretty reasonable IMO for a totally new OEM unit).

Genuine Lexus GX460 Transfer Case

Shop wholesale-priced OEM Lexus GX460 Transfer Cases at LexusPartsNow.com. All fit 2010-2023 Lexus GX460 and more.

www.lexuspartsnow.com

Good call, I’ll verify that.

I did drain the TC fluid and it was in good shape; no metal shavings and it was a little dark but didn’t look as bad as I expected.

Thanks for the link on the TC!

 

[malomalo]

I ran through the test again today, having my helper shifting from N to D while I felt around the drivetrain, and it does somewhat feel like it's from the TC, but it's kind of... blunted if that makes sense. I felt the front and rear diffs as well, and it's definitely more present on and around the TC.

I may just take it up to the Transmission shop I had the rebuild performed at and see if they can better diagnose what's wrong. Maybe a rebuild of the TC if it's just shot bearings or something of that nature would be feasible. I like the idea of a new OEM TC, but 3K + labor is a bit painful at the moment since this isn't a DD. We'll see, I want to get it back on the road.