100 Series Front Diff Failure - Random Chat (1 Viewer)

[krispykritter]

Oh hey I got to experience this recently. The really wild thing is - I wasn't doing anything crazy; heading up 285 to the mountains west of Denver, doing 65 mph and there was an interesting crunch and a moderately loud/fast ticking noise. Pulled over, did an inspect, everything looked fine, went about my day with an interesting noise and no other symptoms.

Local shop that put in my rear elocker a couple days later said it sounded like it was coming from inside the front diff. Did my own investigating, but with limited time, just bought a whole new front diff from toyota (freakin OUCH) and threw it in, then took apart the old one.

Died at 186k miles.

Minor (major?) miracle: the snapped off tooth avoided ending up between the pinion and ring and chernobyl-ing the whole thing at 70 mph on the highway...

 

[ClassyJalopy]

Oh hey I got to experience this recently. The really wild thing is - I wasn't doing anything crazy; heading up 285 to the mountains west of Denver, doing 65 mph and there was an interesting crunch and a moderately loud/fast ticking noise. Pulled over, did an inspect, everything looked fine, went about my day with an interesting noise and no other symptoms.

Local shop that put in my rear elocker a couple days later said it sounded like it was coming from inside the front diff. Did my own investigating, but with limited time, just bought a whole new front diff from toyota (freakin OUCH) and threw it in, then took apart the old one.

Died at 186k miles.

View attachment 3382397

View attachment 3382398

Minor (major?) miracle: the snapped off tooth avoided ending up between the pinion and ring and chernobyl-ing the whole thing at 70 mph on the highway...

Wow, a 4 pinion front diff grenading at under 200k miles! I am assuming it wasn't run dry?
Also, very curious is a new Toyota diff was more cost effective than a new locker and re-grear?

 

[krispykritter]

Wow, a 4 pinion front diff grenading at under 200k miles! I am assuming it wasn't run dry?
Also, very curious is a new Toyota diff was more cost effective than a new locker and re-grear?

No wasn't run dry. I'm got the beautiful sparkles of doom to prove it! When I saw this, I immediately started searching for a new front diff.

Cost effective ... unlikely. It was sadly a time crunch more than anything. I was heading out of town on a business trip for a week or so, and we had a ton of snow in the forecast and my wife needed the 100 running to get herself and the kids around safely.

The cost was around $1750 for the front subassembly and I could get it shipped to a dealership in CoSprings in 3-4 days, in time to install it before my flight left the following monday. I rarely throw money at things but this was just one of those times....

 

[cruiseroutfit]

No wasn't run dry. I'm got the beautiful sparkles of doom to prove it! When I saw this, I immediately started searching for a new front diff.

View attachment 3382476

Cost effective ... unlikely. It was sadly a time crunch more than anything. I was heading out of town on a business trip for a week or so, and we had a ton of snow in the forecast and my wife needed the 100 running to get herself and the kids around safely.

The cost was around $1750 for the front subassembly and I could get it shipped to a dealership in CoSprings in 3-4 days, in time to install it before my flight left the following monday. I rarely throw money at things but this was just one of those times....

Selling the old diff?

 

[krispykritter]

Selling the old diff?

Honestly haven't put much thought into it. The various pieces are in a box in my garage for now. I've heard they go for decent money but debating whether to hang on to it in the unlikely event I need to throw a new diff in it again in the future...or just freeing up the the space it's occupying.

 

[cruiseroutfit]

Honestly haven't put much thought into it. The various pieces are in a box in my garage for now. I've heard they go for decent money but debating whether to hang on to it in the unlikely event I need to throw a new diff in it again in the future...or just freeing up the the space it's occupying.

Should you decide to sell, we buy them regularly @ Cruiser Outfitters

 

[SaturnAscends]

I realize that the 98-99 models have a weaker 2-pinion front diff, but I have to wonder, if the lack of ATRAC, doesn't also contribute to the 98-99 diff failures, since front wheel spin would be unchecked by any electronic nanny?

I think you're right if the driver uses the throttle judiciously, keeping a steady 1500-2000 RPM without "sending it"; however, the system doesn't seem to be that forgiving with a lot of skinny pedal. I think they did a lot of refining of ATRAC for the 200 series.

Honestly, I think the 8" diffs were always undersized for trucks this size; the 80 series got away with it more in the more stable solid axle set up, but they still can break birfs and diffs when pushed hard. I could never figure out why they didn't just keep using the 9.5" in the 60 series, especially when Cruisers kept getting heavier and more powerful with each generation.

Oh hey I got to experience this recently. The really wild thing is - I wasn't doing anything crazy; heading up 285 to the mountains west of Denver, doing 65 mph and there was an interesting crunch and a moderately loud/fast ticking noise. Pulled over, did an inspect, everything looked fine, went about my day with an interesting noise and no other symptoms.

Local shop that put in my rear elocker a couple days later said it sounded like it was coming from inside the front diff. Did my own investigating, but with limited time, just bought a whole new front diff from toyota (freakin OUCH) and threw it in, then took apart the old one.

Died at 186k miles.

View attachment 3382397

View attachment 3382398

Minor (major?) miracle: the snapped off tooth avoided ending up between the pinion and ring and chernobyl-ing the whole thing at 70 mph on the highway...

Must be cumulative wear; was it wheeled or driven in snow a lot? I have read about batches of broken front diffs coming into shops every snow storm, but the issue was apparently never widespread enough for a recall or special service bulletin.

 

[jLB]

I think you're right if the driver uses the throttle judiciously, keeping a steady 1500-2000 RPM without "sending it"; however, the system doesn't seem to be that forgiving with a lot of skinny pedal. I think they did a lot of refining of ATRAC for the 200 series.

Honestly, I think the 8" diffs were always undersized for trucks this size; the 80 series got away with it more in the more stable solid axle set up, but they still can break birfs and diffs when pushed hard. I could never figure out why they didn't just keep using the 9.5" in the 60 series, especially when Cruisers kept getting heavier and more powerful with each generation.

Then again (knock on wood) I’ve got 3 100 series, with a combined 500+k miles, all on original front diffs.

 

[SaturnAscends]

Then again (knock on wood) I’ve got 3 100 series, with a combined 500+k miles, all on original front diffs.

You seem like a responsible driver though. I’m sure all the obligatory 3” instagram lifts don’t help the front diff either. 1” lift and skinny 33s seem like a good recipe for durability; at least that’s my philosophy with IFS trucks.

 

[Wilsil]

My diff didn't fail, but made a ticking noise when turning right.
The mechanic opened the front diff and noticed that the bolts holding the crown wheel to the diff locker were loose.
They were not even finger tight anymore.

 

[IrishPride77]

There are two basic failure modes on the front IFS 100 diff, R&P or spider-gears. The earlier 2-pinion diff is well know to fail at the spiders/cross-shaft but they don't always fail that way, on occasion they too break a ring/pinon. I'm curious what year and what failures you've personally encountered.

This is out of a customers 1999.

View attachment 1753822

View attachment 1753821


Fortunately we had a core front assembly to swap him out in a hurry, he went ARB at the same time. This core will now make a great 4.88/ARB setup... or we have stock front carriers we can use to build anything else too

Had a catastrophic front diff failure about 1000 miles after having the the front passenger side axle replaced by a local shop. Seized up while in town doing 35 mph.

 

[krispykritter]

Must be cumulative wear; was it wheeled or driven in snow a lot? I have read about batches of broken front diffs coming into shops every snow storm, but the issue was apparently never widespread enough for a recall or special service bulletin.

I can't say how it was used prior to me buying it around 135k miles but it was in nearly immaculate condition. Supposedly the original owner was a doctor who rode horses and used this thing to get across stables and such. I bought it in Florida as well.

Since moving to Colorado in early '22, it's been out wheeling in the snow on a regular basis but I'm not really the 'send it' type. As you said - it can't be anything but cumulative damage since I wasn't doing anything other than driving down the highway when it failed.

 

[CameraCruiser]

I asked this in another thread, but seems more appropriate here:

What’s better? ATRAC with the improved 4 pinion front diff year 2000 and beyond, and add air-lockers if needed? Or is the stock ('98-'99) rear locker good enough and change the 2 pin to 4 later? (Seams valid either way).

Also, I am guessing, that if you have ATRAC, it does it’s magic up and until you press the air locker button.

Meaning that if you have an air locker in the rear, lock it for an obstacle, that ATRAC keeps working in the front (but not rear while air locked), and goes back to normal operation when unlocked. So you have the best of both worlds (if willing to pay for an air locker)?

Then getting back to the ‘98-‘99 stock locker. Is it good enough? But should you replace the front diff to 4 pin instead of the original 2 pin? Seems like you need to spend $ either way, and you get onboard air, if you go the ATRAC route, and add an air locker (if all my above operational assumptions are correct).

 

[ClassyJalopy]

I asked this in another thread, but seems more appropriate here:

What’s better? ATRAC with the improved 4 pinion front diff year 2000 and beyond, and add air-lockers if needed? Or is the stock ('98-'99) rear locker good enough and change the 2 pin to 4 later? (Seams valid either way).

Also, I am guessing, that if you have ATRAC, it does it’s magic up and until you press the air locker button.

Meaning that if you have an air locker in the rear, lock it for an obstacle, that ATRAC keeps working in the front (but not rear while air locked), and goes back to normal operation when unlocked. So you have the best of both worlds (if willing to pay for an air locker)?

Then getting back to the ‘98-‘99 stock locker. Is it good enough? But should you replace the front diff to 4 pin instead of the original 2 pin? Seems like you need to spend $ either way, and you get onboard air, if you go the ATRAC route, and add an air locker (if all my above operational assumptions are correct).

You are correct abt ATRAC working on both axles until you start locking. Then it works only on the non-locked axle.
Skip 98-99 for inferior brakes, inferior ABS, lack of ATRAC and weaker front diff.

If you could, try to get 2003+ models that got 5 speed transmission. I know that's not what you are asking abt but it makes a meaningful difference in how well the truck drives.

 

[CameraCruiser]

You are correct abt ATRAC working on both axles until you start locking. Then it works only on the non-locked axle.
Skip 98-99 for inferior brakes, inferior ABS, lack of ATRAC and weaker front diff.

If you could, try to get 2003+ models that got 5 speed transmission. I know that's not what you are asking abt but it makes a meaningful difference in how well the truck drives.

Much appreciated. I had an '03 and a '98, and preferred the '98 simplicity (No screen or nav system - that failed in my '03).

I may just limit my search to '00 and part of '01 (it seems they transitioned to the nav screen around then) to get ATRAC and the 4 pin front diff. Otherwise I'll feature creep up to the end of the 100s to get the somewhat more powerful engine. It never ends.

 

[krice118]

Go for rear locked 98-99. More fun. But I’m biased. If budget is $15-20 consider an LX570…..

 

[CameraCruiser]

Go for rear locked 98-99. More fun. But I’m biased. If budget is $15-20 consider an LX570…..

I'll never say never, but I really like the size of the 100 series (and 80s too) over the 200 series and 570 LXs. I just feel like I am wearing them, verse being in them.

 

[SaturnAscends]

I asked this in another thread, but seems more appropriate here:

What’s better? ATRAC with the improved 4 pinion front diff year 2000 and beyond, and add air-lockers if needed? Or is the stock ('98-'99) rear locker good enough and change the 2 pin to 4 later? (Seams valid either way).

Also, I am guessing, that if you have ATRAC, it does it’s magic up and until you press the air locker button.

Meaning that if you have an air locker in the rear, lock it for an obstacle, that ATRAC keeps working in the front (but not rear while air locked), and goes back to normal operation when unlocked. So you have the best of both worlds (if willing to pay for an air locker)?

Then getting back to the ‘98-‘99 stock locker. Is it good enough? But should you replace the front diff to 4 pin instead of the original 2 pin? Seems like you need to spend $ either way, and you get onboard air, if you go the ATRAC route, and add an air locker (if all my above operational assumptions are correct).

I think the whole “2 pinion is weak” thing is way overblown. Just drive it with some finesse and you’ll be fine. In fact, I’d trust the 2 pinion without the shock loads of ATRAC more than the 00+. IME, ATRAC is not even that effective if you’re on wet/slick terrain and/or start lifting wheels.

 

[CameraCruiser]

I think the whole “2 pinion is weak” thing is way overblown. Just drive it with some finesse and you’ll be fine. In fact, I’d trust the 2 pinion without the shock loads of ATRAC more than the 00+. IME, ATRAC is not even that effective if you’re on wet/slick terrain and/or start lifting wheels.

Yup. I am beginning to think any pre or non factory navigation equipped LCs will do for me and my use plans. I can always add an air locker if desired, or circumstances/breakage demand.

 

[ClassyJalopy]

I think the whole “2 pinion is weak” thing is way overblown. Just drive it with some finesse and you’ll be fine. In fact, I’d trust the 2 pinion without the shock loads of ATRAC more than the 00+. IME, ATRAC is not even that effective if you’re on wet/slick terrain and/or start lifting wheels.

My experience has been otherwise. I find ATRac actually better than front locker in many off camber slippery slopes. Also,2 pinion is weaker design objectively, Mr. T. recognized that and switched to 4 pinion and never looked back.
Pre 2000 also got a 3 channel ABS which treat both rear wheels together, which is noticeably worse than later models in hard braking on curves or uneven surfaces.
98 and 99 also lack VSC, which has I have found useful a couple of times of slippery road surfaces or when I took an exit too fast.

Finally, the brakes are more effective on 2000+ plus model years.
I used to own a 98 with a ton of maintenance including new brake booster and I triple locked it too. The differences I mentioned are based on my own extensive experiences.