Pinion carnage twice What is the cause?

[OakieOffroad85]

Below is a set of 4.88 genuine gears for a toyota 8 inch diff. I run an arb and stock axleshafts with 33's as a daily driver and 36's when I roll to the trails. I have dual cases both with stock gearing. I run my rig pretty good but I dont beat on it hella hard.

I had my gears set up by a pro diff shop. I broke in the gears properly and always had oil in there. But I have blown out two sets of gears both in my rear end. Both of my pinions snapped off 4 teeth. Right at the root of the tooth.

The first one i was doing burnouts in the rain on a slicker than cat sh*t street and i heard kapow. That was about 2 weeks ago.

The second one I took out of my front and was set up by the same builder. I moved this diff to the back so I could drive around on the freeway.

I have only had the gears in the back for two weeks and took them out on a mild trail 2 days ago. Yesterday when I was driving up to my friends house at about 10 miles an hour in first gear up a slightly steep hill i hear another kapow.

At this point I knew exactly wut it was. Another freakin set of gears went bad on me. And after i took it apart promptly found out i had snapped another 4 teeth off of the pinion directly from the root of the tooth.

Now im looking for your guys opinions on why this is happening. Bad batch of gears? or bad install? I have my suspicions with the builder but both of the sets had a perfect pattern set up on them?

I need a clue


Here is a pic of the pinion. If you look closely you can see how deep the break was.


Another picture before i took them apart.


And heres the teeth I pulled out

[tanman2003]

part of the problem is probably the genuine gears.

[ogyoda]

get Bobby to freeze ane bake your next set.

[ROCKILLER]

Originally Posted by ogyoda

get Bobby to freeze ane bake your next set.

Why would you cryo a set of junk genuines? I would guess that your "pro" set them up loose. Meaning the backlash was too high. If I were you I would get them warrantied and set them up yourself next time. It will be well worth it to buy some simple tools like a dial indicator and a torque wrench if you dont have one and get it setup right. I would also build a jig to hold the pinion flange and also from the other side so you can securely hold the third to your workbech.

[somebourbon]

I've run Genuines in all of the 14 axles I've built and never had any problems. From Dana35s up to 14 bolts.

[OakieOffroad85]

Yeh ive had a feeling its the gears and the installer. When he put them together he didnt use a crush sleeve or any shims for the pinion. My friend told me he did it wrong when he took my gears apart for me and built my new ones.

The builder swears he builds bomb proof stuff. The first diff was a little bit loose. But the second one I broke was perfectly fine. I will have pictures of that soon.

I was trying to figure out why the gears were breaking at their strongest point because at that point it couldnt just be the installer but also the integrity of the gears.

Luckily i already do have a warranty on these gears through 4 wheel parts and i can keep blowing up as many as I want. But i was thinking about going to a set of Yukon or precision gears. Driving around town on the front is a pain in the ass specially when you cant go over 50 because of a square driveshaft.

[tanman2003]

Originally Posted by OakieOffroad85

Yeh ive had a feeling its the gears and the installer. When he put them together he didnt use a crush sleeve or any shims for the pinion. My friend told me he did it wrong when he took my gears apart for me and built my new ones.

well there you go, the problem.

[OakieOffroad85]

Yeah but i did see like one spacer between the last bearing and the pinion head. I said isnt that a shim right there. And he told me no i guess its just the bearing spacer. But the pattern he set up on the gears was pretty damn good almost close to perfect.

My friend told me the only problem with the way he set it up is that it will come loose easier. Well my last diff wasnt loose at all. So thats what leads me to suspect the gears.

[somebourbon]

There's only a few companies that produce their own gears. Not all the gear companies have their own foundry. I don't which, but they just slap their name on a manufacture's gear. Just the same as some companies get the same shocks from the same manufacturer. It's all the same, pretty much, IMO

[OakieOffroad85]

Yeh ive heard that before also. I wasnt quite sure if it was true but since many people are saying it I guess it is.

Well im on the verge of making a decision based on your guys opinions. And I dont think ill be taking my gears to the old installer again. Obviously he builds exploding pinion diffs.


Thanks for the input.

[White Goat]

call up marlin crawler and have Rocky build you a diff.

[Moab Austin]

just because there are no shims doesn't mean it is set up wrong..

was the pinion loose? Like I mean side to side..like you could shake the yoke?

if he didn't use a crush sleave did he use a solid shim? like a little peice of pipe looking thing?


IF gears were setup right, I would guess that the wrong yoke was used, and the crushsleave wouldn'tget enough crush, or the solid shim didn';t get shimmed right

do you have the stock yota gears? if so stand both pinions up side by side and compare

[81toyot]

i dont think its the brand, cause ive ran cheap ass 5.29's and I can light up the tires on dry ground and no breakage...same on the trail when I use my
37's. I second the backlash answer.

[VinSil]

Most of the time it's installer error. Genuine gears aren't the greatest in the world...there is a reason they can lifetime warranty them. Cheap gear sets.



Too much backlash, not enough crush on the sleeve or if he used a solid spacer he might not have had the pinion depth set correctly. I second the buy a dial indicator and a torque wrench and do them yourself and leave that "pro" along. You might also consider using a different brand of gears. Beat on my Yukon 5.29's all the time with a ARB and 37's...they are holding up fine. Just take your time and get a great pattern and make sure your backlash is within tolerance and they will treat you right. It's not rocket science, you can do it.

[ROCKILLER]

Originally Posted by somebourbon

There's only a few companies that produce their own gears. Not all the gear companies have their own foundry. I don't which, but they just slap their name on a manufacture's gear. Just the same as some companies get the same shocks from the same manufacturer. It's all the same, pretty much, IMO

Genuine makes their gears and they ARE crap. That being said, I have installed 20-30 of them and have only had a few breakages. If you dont install the crush sleeve, when you tighten the pinion, your preload will be too high too soon. Basically, you wouldnt be able to get the pinion tight enough not to deflect under a load without a crush sleeve or a solid spacer with shims. You dont shim a crush sleeve. The big flat thing past the bearing is the oil slinger. Do some reading and learn to do them yourself. Its not that hard.

[300sniper]

my genuine gears didn't even last through the break in period in my 9". the pinion wore away like it was not hardened at all. i could still see the set up paint on the ring gear. when i replaced them with a more reputable gear set i also replaced my front d44 genuine gears. they showed wear all ready and only had a couple trail runs on them.

sure some people get away with running genuine gears but it wasn't me. never again will i run them. also, 4wp sure asked a lot of questions for a "no question asked warranty". they almost didn't exchange them because i didn't want to buy another set up kit from them. the replacement gear sets were sold new in the box after that.

[PARTYHOUND]

These guys are more than likely right w/the cheap gears/improper gear setup answers, but something else that could be the problem....is your axle bent?

[OakieOffroad85]

Im pretty sure the guy didnt set them up right. The first time i broke the pinion I didnt have a Pinion spacer. All there was was a shim behind the main pinion bearing to set the backlash. There was nothing inbetween where the crush sleeve goes and yes the first one did come loose and broke on me.

The second one was set up the same way. But was not loose at all. In fact it was still as good as the day he built it. So thats what i thought it might be the gears.

Thanks for all your input guys. Very helpful.

[MCgiver4x4]

Originally Posted by tanman2003

part of the problem is probably the genuine gears.

x2

a ritchmond pro gears should put end to your problems

[ogyoda]

Originally Posted by ROCKILLER

Why would you cryo a set of junk genuines? I would guess that your "pro" set them up loose. Meaning the backlash was too high. If I were you I would get them warrantied and set them up yourself next time. It will be well worth it to buy some simple tools like a dial indicator and a torque wrench if you dont have one and get it setup right. I would also build a jig to hold the pinion flange and also from the other side so you can securely hold the third to your workbech.

Do I need to spell it out, genius? Buy them that way from the man in the first place, from Longfield (Fucking Barney music in background). No shit it sounds like excessive backlash. rockiller is right, though. Do it yourself and you can be sure it's done right.

[somebourbon]

Originally Posted by ROCKILLER

Genuine makes their gears and they ARE crap. That being said, I have installed 20-30 of them and have only had a few breakages. If you dont install the crush sleeve, when you tighten the pinion, your preload will be too high too soon. Basically, you wouldnt be able to get the pinion tight enough not to deflect under a load without a crush sleeve or a solid spacer with shims. You dont shim a crush sleeve. The big flat thing past the bearing is the oil slinger. Do some reading and learn to do them yourself. Its not that hard.

Well, I've never had any problems. That's just my experience.

[VinSil]

Originally Posted by OakieOffroad85

Im pretty sure the guy didnt set them up right. The first time i broke the pinion I didnt have a Pinion spacer. All there was was a shim behind the main pinion bearing to set the backlash. There was nothing inbetween where the crush sleeve goes and yes the first one did come loose and broke on me.

The second one was set up the same way. But was not loose at all. In fact it was still as good as the day he built it. So thats what i thought it might be the gears.

Thanks for all your input guys. Very helpful.

You don't set the backlash with the pinion shims either(that is done with the spaners). If the first 3rd he setup had the spacer missing (he's a FOOL, Toy thirds are simple to setup!) I'm going to guess he fawked the front 3rd up JUST as bad...which is why they both broke under conditions they shouldn't have.

Good luck.

[NOODLES]

sometimes you have to hit the carrier side to side after putting in the adjusters, to make sure the carrier bearing's races are in there straight and not cock eyed. this could cause too much back lash after the third is installed and driven on. and you will not notice it until something breaks.
I have fawked one up like that. first third member I ever built. pull it apart...too much slop. it was good when I put it in..I thought. bearing caps were tight, adjuster locks in place. but too much backlash. I double check everything now.

[OOP'S]

Pinion carnage twice What is the cause?

Shitty set-up and shitter gears. Give River City Diffs (known as Gearman on the board) in Rancho Cordova a call, he is the best in the west. But do not bring him GG Gears, he will not set them up and he does not really like Yukon either!!!! Not that far to drive if you live in Pin-Hole, CA and well worth it.

[TBItoy]

I do believe that Bobby's friend that tests stuff for him (red truck on 42s) it running some baked and frozen Genuine Gears.