Shorter bolt/stud for Rear Axle Hub compared to original Toyota part. (1 Viewer)

[Kernal]

Edit: removed all references to AISIN in the post to avoid confusion
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Posting this up to show the difference comparing an OEM original rear bolt/stud (90116-08325) for the rear axle hub to a different Toyota bolt/stud (? 90116-10074 not confirmed) which came in a "rear hub kit" of 6 studs, 6 nuts, 6 flat lock washers, and 6 cone washers.

Bottomline: The replacement bolt/stud in the kit, (? 90116-10074), is shorter overall along with a shorter unthreaded section. Not sure of the significance of these differences however (discussion below).


Long version:

Bolt/Stud dimensions:

Bolt/Stud (? 90116-10074) in the kit
overall = 34.4mm
short threaded section = 11.6mm
long threaded section = 16.8mm
unthreaded section = 6.3mm

Original Toyota stud (90116-08325)
overall = 42 mm
short threaded section = 11.9mm
long threaded section = 16.7mm
unthreaded section = 13 mm

Length differences 90116-08325 vs 90116-10074

Overall length: 42mm vs 34.4mm = 6.6mm difference

Unthreaded section length: 13mm vs 6.5mm = 6.5mm difference

So what's the point?? The bolt/stud in the kit is shorter in both the overall length and the unthreaded section.

And if you installed the stud short end in you would still lose about two threads on the end of the stud for the nut due to the design. But the original studs were (are) designed to be installed long end in (see photos).

And what's the importance of the unthreaded portion length?? IDK and I'm not a mechanical engineer but looking at the original studs it appears that the cone washer is designed to squeeze onto the unthreaded portion of the stud ie: to make a solid unit (cone washer-stud-flange). If this is a correct assumption then would the stud with the shorter unthreaded portion provide adequate grip for the cone washers?? In that situation the cone washers would be squeezing/gripping mostly on the threads of the long section of the shorter stud, if that makes sense. (see photos)


If you look closely at the used original stud there's a rust line part way down the unthreaded section. This appears to line up with the location of the cone washer once the nut is torqued down ie: there's no rust under where the cone washer was squeezing against that unthreaded section:
Then compare the length (shorter) of the unthreaded portions of the AISIN stud.

Note also almost two less threads at the top of the long section of the shorter stud and the (preapplied) green thread locking compound on the short section indicating the short end is meant to go into the hub (The longer Toyota studs go long end in):

This shows six original studs after removal which were originally installed by Toyota long side in (the hub). Note the slightly more shiny bottom edge of the unthreaded section, this is where it butts into the threaded hole in the hub.

Another possible tip-off which way the OEM studs were designed to be installed; the end that goes into the hole is flat, the exposed end is slightly dome shaped. FWIW

Most people have seen a rear axle hub before, just added for those that haven't. Most of the studs have been removed, one is part way out, one still tightly installed. There are two short 8mm pins that line up with holes on the flange. Measuring the depth of the stud holes got interesting results, most were ~33mm deep but a couple on each of two hubs were closer to 27mm. IDK why the difference in hole depth as nothing appears to be stuck in any of the holes which were cleaned with a cleaning tap before measurements were taken.

Click photo twice to magnify:

 

[Kernal]

Photo of the Axle Hub kit (one side):

 

[OGBeno]

Those are 8mm diff studs.

Aisin doesn’t make hardware for Toyota.

Hardware manufacturers make them for Toyota.

 

[IdahoDoug]

Interesting stuff.

 

[Njck22]

cone washer needs flat surface to transfer forces as originally designed.

 

[Kernal]

OGBeno had the answer (diff studs); that explains it (with a lot less words than I wrote).

 

[cruiseroutfit]

Those are 8mm diff studs.

Aisin doesn’t make hardware for Toyota.

Hardware manufacturers make them for Toyota.

Full disclosure, we (Cruiser Outfitters), have never said they are made by AISIN. They are Genuine Toyota and listed that way too. I see Jason has mentioned this to Kernal via email but somewhere it's getting lost in communication. These parts are OE Toyota.

It sounds like Jason and the team at the shop have this all under control and will credit you for the unused parts

 

[sjpitts]

Full disclosure, we (Cruiser Outfitters), have never said they are made by AISIN. They are Genuine Toyota and listed that way too. I see Jason has mentioned this to Kernal but somewhere it's getting lost in communication.

View attachment 3181208

The description does say "Front Axle AISIN Hub/Drive Flange Stud Kit". I could see how someone might be confused and think this is an AISIN kit and not a Toyota kit for an AISIN hub.

 

[cruiseroutfit]

The description does say "Front Axle AISIN Hub/Drive Flange Stud Kit". I could see how someone might be confused and think this is an AISIN kit and not a Toyota kit for an AISIN hub.

I suppose, first time I can recall hearing that interpretation but we can easily clarify/update that on CruiserTeq, I'll get with Bryce on that. Easy fix.

cone washer needs flat surface to transfer forces as originally designed.

Do they? A plethora of Land Cruisers running cone washers with the 94512-00800 or 94512-01000 split spring washer(s) from Toyota in front and rear applications alike, AISIN hubs, drive flanges and rear full-float applications. So to be fair, 'as originally designed' was the split spring washer and cone washer, not the flat washer. Yes, Toyota changed that in 1990 but I'm personally not convinced it's superior and I still setup any of my personal Cruisers with the split spring washer/cone washer as Toyota did for those many years.

I've never heard of a cone washer failure/mishap due to the factory split spring washer being used. Curious if you have you?

 

[cruiseroutfit]

Updated description on our end. Hopefully this prevents any further confusion.

 

[Njck22]

I suppose, first time I can recall hearing that interpretation but we can easily clarify/update that on CruiserTeq, I'll get with Bryce on that. Easy fix.



Do they? A plethora of Land Cruisers running cone washers with the 94512-00800 or 94512-01000 split spring washer(s) from Toyota in front and rear applications alike, AISIN hubs, drive flanges and rear full-float applications. So to be fair, 'as originally designed' was the split spring washer and cone washer, not the flat washer. Yes, Toyota changed that in 1990 but I'm personally not convinced it's superior and I still setup any of my personal Cruisers with the split spring washer/cone washer as Toyota did for those many years.

View attachment 3181362

View attachment 3181361

View attachment 3181363

I've never heard of a cone washer failure/mishap due to the factory split spring washer being used. Curious if you have you?

I am refering to the cone washer clamping on the unthreaded section of the stud, as described in the original post. Spring washers on top will have no effect, as you said. The cone washer centers and transfers force from the drive flange to the hub. Threads do not support the same radial load as unthreaded shafts due to the small contact area. Stress = Force/Area. Theoretically this would result in thread deformation. Has this ever actually happened? No. But no design in machine elements ever would use a cone washer over threads.

 

[Kernal]

Sorry this thread took a slight turn away from tech, it was not meant to be about AISIN parts versus Toyota, or about CruiserTeq (a great vendor for the MUD community), (I didn't mention their name in my original posts).

The thread's purpose was purely technical to try to figure out from the MUD hive mind if the shorter studs in the kit were an acceptable substitute for the original rear hub studs, apparently many people are running these studs in their hubs without issues.

It was just a mystery at first not being familiar with the rear diff carrier studs (OGBeno was, of course) but now we know that shorter stud works and appears to be ?? 90116-10074 or close to it (somone correct me if that's wrong).

 

[cruiseroutfit]

No, that is not the stud we use. That said, as I replied to both your latest email and private message:

I’m not interested in continuing the back and forth via replies to your PM’s, emails and this thread. We’ve offered a refund above and beyond the cost of the studs themselves. We’ve updated the CruiserTeq website to more clearly indicate they are OEM Toyota parts so this doesn’t happen a second time. We’ve sold and installed thousands of that combo over the decades, we are comfortable with the application.

 

[Njck22]

So why do you use the shorter toyota stud in the kit versus that longer proper part that toyota specifies?
Or are you saying that the picture on the site is incorrect?

 

[cruiseroutfit]

So why do you use the shorter toyota stud in the kit versus that longer proper part that toyota specifies?
Or are you saying that the picture on the site is

A. We sell, stock and offer both amongst other variants, aftermarket, ARP, etc. Long stud is part# HUB08325B.
B. I like the thread-lock, material, plating and availability. Cones don't come loose, studs don't get damaged and the clamping force they provide works great. The studs provide the necessary alignment and clamping force. We've sold thousands of those kits, I'll have to chat with our tech team and engineer but I'm not familiar with a single failure across our customers many uses and personal vehicles.

 

[Kernal]

Edited this post after sleeping on it and decided to not use the incorrect too-short hub studs described in the thread above. I'll either toss them or if they work for a diff carrier (to axle housing) as OGBeno mentioned I may use them there.

Bottomline: there's just no engineering data to back up the use of an incorrect stud in a critical application. One way to look at it is that Toyota engineers would have designed and specified the OEM length/design hub studs for a specifc reason, safety, to hold the axle flange securely to the hub.

The engineering (by Toyota) is irrespective of (ie: not dependent on) anecdotal stories of no (known) issues or accidents caused by a flange or studs that may or may not have come loose while using too-short studs.

Just imagine for a minute (hypothetically speaking) if Toyota had specified a too-short stud for this application and then tried to defend themselves in court after a rear axle shaft pulled out while a family of five was drving down the highway causing a roll-over??

"Well your honor, here at Toyota we just liked these too-short studs and, gee whiz, we just liked them". Nope.

Personally, I'm not willing to risk potential loss of an axle shaft at highway speed while my wife or children are riding in and/or driving the vehicle.

Others can make their own decisions.

ps: thanks to those that had tech related comments/questions.


End of story (I hope)