Broken Idler Gear Tooth

[hatfieldcb]

Well, I'm wondering if I may have found one of my problems in my project FJ40? When I traveled to and from my club meeting Wednesday night I noticed a bad knocking sound in the drive train. We were guessing it might be the transmission. I thought it might be the t-case input gear. So I drained the tranny & transfer case and I took off the rear cone. The t-case input gear had not moved. It was fine. Then I pulled the side cover off the t-case and found a broken tooth on my idler gear in my Orion. Do you suppose this could be causing my knock?

[cruiserbrett]

that sucks! Have you contacted AA to see what they'd warantee?

[hatfieldcb]

They're not open at this hour. I just found it 30 minutes ago.

[cruiserbrett]

True. hopefully they will help out...

[Poser]

Oh my....



Anything else on the magnets?

Any other chunks of ???

[hatfieldcb]

Originally Posted by Poser

Oh my....

Anything else on the magnets?

Any other chunks of ???

Now that you mention it.... There were a few chunks of silver stuff that came out when I pulled the AA cross member off the other day. Some of it was finely ground, but there were a few larger chunks. When I drained the t-case tonight, of course, there was lots of fine silver colored particles in it. The t-case magnet was loaded with metal. Kind of like what treeroot's looked like. I assume that's somewhat "normal" for an Orion.

Pin_head said he didn't think the chip was causing my noise, unless the cluster gear is sliding back and forth some. I may just button it back up and put some new oil in it and run it a little more. It's either that or find another t-case.

Moab is only 4 weekends away.

[65swb45]

Wow. I have not heard of any gear failures in the Orions, and chipped gears are not common in any event.

I would NOT call AA until you had a chance to pull the t-case and inspect for possible trauma-related causes.

Unless you see sharply defined edges across both faces of the break [which would tend to indicate a completely spontaneous fracture] I would think it more likely that either the gears moved in relation to one another [causing stress], or that a 'foreign' object came between two gears.

You should make an effort to learn the answer to this before you call.

Best

Mark A.

[65swb45]

Originally Posted by hatfieldcb

Now that you mention it....

Pin_head said he didn't think the chip was causing my noise, unless the cluster gear is sliding back and forth some. I may just button it back up and put some new oil in it and run it a little more. It's either that or find another t-case.

Moab is only 4 weekends away.

NOT!!! You owe it to your own safety to pull that case. If there is a chance that another tooth is damaged, you need to know. A tooth can lodge between the gears and cause the case AND THE VEHICLE TO COME TO A SUDDEN AND QUESTIONABLE STOP.

PLEASE do this Chris. We want to keep you around.

[hatfieldcb]

Originally Posted by 65swb45

NOT!!! You owe it to your own safety to pull that case. If there is a chance that another tooth is damaged, you need to know. A tooth can lodge between the gears and cause the case AND THE VEHICLE TO COME TO A SUDDEN AND QUESTIONABLE STOP.

PLEASE do this Chris. We want to keep you around.

OK Mark. Thanks. I will locate a substitute case and pull this one.

I suppose I could have done this myself when installing my gears. I re-did it several times to get the pre-load right.

My SM420 is popping out of 3rd gear as well. Maybe I should pull the whole mess and start over.

[65swb45]

Thank you Chris. I know you've been waiting a LONG time to drive this truck, and I just wanted to make sure that your anticipation wouldn't cloud your judgement.

Have faith in cruiser karma and your local cruiserheads. I'd stake money that they find you a transplant AND have it in your rig in a week.

See you in Moab.

[cruiserbrett]

Originally Posted by 65swb45

Unless you see sharply defined edges across both faces of the break [which would tend to indicate a completely spontaneous fracture] I would think it more likely that either the gears moved in relation to one another [causing stress], or that a 'foreign' object came between two gears.

It looks like there was at one point a clearly defined fracture that got mashed further. In the center of the chipped tooth it appears to be smooth and somewhat rounded off, indicative of something being wedged in the low speed output gear at one time, likely after the failure. This will certainly cause a knocking noise. A left over piece of gear stuck in the tooth valley will certainly mash the "clean" fracture.

I had a stock t-case where a tooth chipped, and the chip was wedged in the valley between two teeth in the mating gear. It caused enough interference to make an awful racket for a few hundred yards before it split the aluminum case in two, which landed on the skid plate. Obviously the consquences with a cast iron orion would be worse...

I would take a small inspection mirror and rotate the t-case output shaft(jack up one rear wheel if you dont have an auto locker, in 2wd) and see what the low speed out put gear looks like. I bet you find a small piece of gear wedged in between two teeth.

[hatfieldcb]

Thanks guys. I will be pulling the case tomorrow. I'll keep you posted.

[inkpot]

Howdy! I agree with Brett and Mark. Something has been pounding on the face of that fracture. I'm willing to bet there is bad news on the opposing gear. Also, notice the wear pattern on the good teeth. Your only running about 75% contact on the face. Is the other gear just narrower, or is it that far out of alignment? Looks like there are small nicks on the top of the near two teeth. To me it looks like the heel to toe pressure is not even. I would be suspect of the two gears not running square to each other. Maybe a bad bearing or worn/crooked shaft. Not trying to rain on your parade, but I work with gears that are 44" x 2", and we had to change 3 of them out on Tuesday due to tooth damage. John

[mustardfj40]

Originally Posted by inkpot

. Your only running about 75% contact on the face. Is the other gear just narrower, or is it that far out of alignment? Looks like there are small nicks on the top of the near two teeth. To me it looks like the heel to toe pressure is not even. I would be suspect of the two gears not running square to each other.

I believe that's the design of the Orion, the teeth of idle cluster are wider than the teeth of the output gears. I remember on the stock transfer case they're same width but not on the Orion. At least on my early serial number Orion.

[Sputnik40]

When I bought my current FJ40 (76) some 12 odd years ago, it came with a bunch of spare parts - including a clean t-case housing. I immediately sold it for $100 to offset renovations. A few years later when I got around to pulling the t-case to rebuild and install 3-speed gears, upon dis-assembly found that the prior owner had rebuild a badly damaged case - apparently something went (similar to your broken tooth) and said pieces bounced around the case causing about a dozen small dings (which also had cracks) and then wedged in behind the output shaft gear closest to the tail - it then sat there and created a nice deep gauge (at least 1/8" deep, and about an inch across - with a total diameter of like 4 inches. Needless to say - I had to find another case.

I just bought an Orion HD - I can't imagine which would prevail - a broken bit of gear teeth, or the case - obviously the gears are a bit harder, but methinks something would lock up before the case gauged or dinged or cracked like that old aluminum one did.

Agree - pull and do a full inspection.

[Sputnik40]

Can you see if the front nosecone - output is loose? Not sure how much your skidplate covers. That would cause misalignment and uneven contact on idler gear?

[65swb45]

Originally Posted by Sputnik40

Can you see if the front nosecone - output is loose? Not sure how much your skidplate covers. That would cause misalignment and uneven contact on idler gear?

And a heck of a leak!

Just as an aside [since you guys brought up case damage]....next time you're at my shop, take a look at my door stop. Stock 1976 vintage t-case idler, run damaged behind a 350 cheby.

EVERY TOOTH on one side of the idler was WIPED CLEAN and somehow the aluminum case DID NOT BREAK!

I have NEVER seen this happen before or since. Just this once.

[hatfieldcb]

Found the culprit. Why would a thrust washer do that? It's number 25 in the bottom line of schematic below. It munched 3 other teeth besides the first one.

[calstyl2]

WOW...............

Hey Chris, if thats a AA part and you think they should warranty it, try Geno at AA, he helped me with a Orion issue I had and in a hurry too............

[hatfieldcb]

Originally Posted by calstyl2

WOW...............

Hey Chris, if thats a AA part and you think they should warranty it, try Geno at AA, he helped me with a Orion issue I had and in a hurry too............

Thanks Rob. I think it was the stock Toyota thrust washer.

[65swb45]

I have torn down and rebuilt over a hundred t-cases, and I have NEVER seen a thrust washer fail. That is super strange Chris. Of course that doesn't help answer your question, just saying.

Logically, the thrust washer should not have any more load on it than the preload you set on the output bearings, as the output shaft and the output bearing capture the thrust washer. The thickness of the gear is nowhere near wide enough to put any load on the thrustwasher.

Were there any problems setting the preload on the bearings?

Come to think of it, I think there was a preload problem on MY Orion when I went to set it up, which was conveniently solved with the stepped thrust washers I got from Poser.

This may be the key.

Mark A.

[hatfieldcb]

We'll see what AA says. This may have been installer error.

[Pin_Head]

Originally Posted by hatfieldcb

Pin_head said he didn't think the chip was causing my noise, unless the cluster gear is sliding back and forth some.

In all fairness, you asked me if a chipped tooth would make a knocking noise before you posted up pictures of the gear. After looking at it, I would say that is more than a just chipped tooth.

[hatfieldcb]

Originally Posted by Pin_Head

In all fairness, you asked me if a chipped tooth would make a knocking noise before you posted up pictures of the gear. After looking at it, I would say that is more than a just chipped tooth.

No worries. I didn'