12 bolt strong enough for t-56?? - NJFBOA - Home of New Jersey's Camaros and Firebirds

transmaro93 · 07-31-2010, 12:41 PM

Before i start let me say im in no way blaming this on the seller of the rear. just a disclaimer there. So i bought a used Strange 12bolt 33spline axles eaton posi 4.11 gears out of a 00 WS6. i was told the rear was never raced and only had around 2K miles on it. For all the break in use and dyno use the rear was fine, very quiet and shown no signs of failure or sevear wear. So i finally get to the track with the car and after 3 runs and 2 of those runs only launching at 4K its whining really bad on accel and growling really bad on decel. If i had to guess id say the pinion bearing took a crap, but i haven't opened it up yet. I was told numerous times that a s60 would be heavy and overkill for my set up and that a 12 bolt would be sufficient and this is what happens after 3 runs that weren't even that rough. whats going to happen when i dump it at 5K+. and i wasn't even getting good traction best was only a 1.8 60'. Im probably gonna fix this one and see what happens or is it not even worth it should i just fix it and sell it to someone with an auto that it might not break on and then get a S60. Just really suck that either way im out a crap load of money than if i just bought the S60 to begin with. Should have gone with my gut. any EXPERIENCED advice would be helpful. THanks

Mike · 07-31-2010, 01:03 PM

mine whines like hell, mostly on decell, but it still works. mine was worse before i redid the bearings... bearings fixed it a little, but i know the problem is the gears or posi now...

BonzoHansen · 07-31-2010, 01:39 PM

Mike wasn't the problem with yours related to using sythetic gear oil?

My experience is used rears are a crapshoot. In general 12 bolts will hold up to tons of power, at least real gm ones. 8.5" rears too. I think if that was my car I'd fix the rear you have.

transmaro93 · 07-31-2010, 01:44 PM

K thanks guys... still open for more feedback on this. I was using just strait lucas gear oil, not synthetic just so that is known. I mean the rear works i made it all way home from etown with it with no problem besides the noise, but the fact that it was working well and then after some abuse it starts making noise is leading me to believe something is deffinitly wrong under there. my old rear whines a little (nothing like this) but that was set up good and worked great so i wasnt worried about it at all. This is much worse

transmaro93 · 07-31-2010, 02:30 PM

well i just jacked it up and just from turning the tires by hand side to side untill the gears catch (quick way just to see how much play is in there) the left side seems pretty good but the right side has alot more play than the left side does... any idea what that might mean.. somthing with the diff?dont know why that would cause gear whine though...

1QWIKBIRD · 07-31-2010, 02:49 PM

The Moser 12-bolt in my car has seen more than its fair share of abuse. Its behind a T56, has 3.73 gears, (clutch type) posi, 31 spline axles, and support style rear cover. It is quiet and you kinda forget its there. I run dino based lube with a bottle of GM additive as per Moser's recommendations. My only complaint is the 4 short bolts that are used for the Torque Arm mount, they backed out at one point and tore up the Spohn mount, but aside from that the rear has performed flawlessly. I've dumped the clutch numerous times at 5000 rpm and above on ET-streets and have never had problem. The car as gone 1.7's in the 60 (not great by any means) and will trap at 119-121 +/-. I think proper gear set-up is absolutely crucial and a little luck can't hurt.

Good Luck with your situation

transmaro93 · 07-31-2010, 03:13 PM

welli pulled the cover and the right side axle goes into the eaton and i can see where the extra play is coming from but i dont see anything that looks outawack.. it just clunks back and forth i dont know if that is normal or not i dont have alot of experience with these diffs my last rear had an auburn in it. the ring and pinion do look kinda weird though i cant see alot of the pinion but it looks like it was rubbing something and the eaton unit it self has an almost polished part of it that looks like it was rubbing something... i wasnt planning on doing this today but i cant walk away from it hah.. the pinion doesnt seem to have alot of play in it... ill need to get a good dial indicator next week and check the lash...

LTb1ow · 07-31-2010, 06:02 PM

I would try and fix it, big investment to just give up on and move on...

Worst case, I'll buy it off ya.

07-31-2010, 06:43 PM

ill let you know how my 12 bolt holds up when i launch off of the trans brake with a 250 shot

its been good so far with 6k rpm clutch dumps and 1.6 60s (that was with 4.30s)

transmaro93 · 07-31-2010, 07:00 PM

yea i mean nothing really looks too crazy in there... i did notice a slight chipped tooth when i was prepping it for install onthe car and it never made noise untill the track passes... but it doesnt look like anything is erally messed up in there... the pinion is leaking a little and slinging a little bit but thats alls i noticed...

1QWIKBIRD · 08-01-2010, 09:17 AM

Quote:

Originally Posted by transmaro93

welli pulled the cover and the right side axle goes into the eaton and i can see where the extra play is coming from but i dont see anything that looks outawack.. it just clunks back and forth i dont know if that is normal or not i dont have alot of experience with these diffs my last rear had an auburn in it. the ring and pinion do look kinda weird though i cant see alot of the pinion but it looks like it was rubbing something and the eaton unit it self has an almost polished part of it that looks like it was rubbing something... i wasnt planning on doing this today but i cant walk away from it hah.. the pinion doesnt seem to have alot of play in it... ill need to get a good dial indicator next week and check the lash...

Quote:

Originally Posted by transmaro93

yea i mean nothing really looks too crazy in there... i did notice a slight chipped tooth when i was prepping it for install onthe car and it never made noise untill the track passes... but it doesnt look like anything is erally messed up in there... the pinion is leaking a little and slinging a little bit but thats alls i noticed...

You need to have an experienced set of eyes look at that rear. There should be no chipped teeth, the diff and the pinion should not have "polished" areas on them from rubbing against something. If you continue to run it like that, it could completely destroy itself. Post up some pics I'm sure someone here have enough experience to help figure out the problem.

chris

transmaro93 · 08-01-2010, 09:54 AM

yea i mean i'm not incompetent... im not a rear specialist but i know what im looking at. I would help to have someone that works on them all the time check it out. i either need to buy or borrow some tools next week to check the back lash and then check the preload on the pinion... if i had to guess i would say the pinon lost its preload and that's why its whining and growling and also why the pinion maybe have moved and rubbed and would also explain why its leaking. if this is the case the only thing i don't know is that if the gears at this point are unusable... i drove maybe the most 40 miles like that home from etown and then its been parked ever since... with all that said i read numerous threads on the crap quality control that strange apparently has from stories of them not setting the gears up right to just flat out leaving out seals and reluctor wheels and stuff. one guy on tech has a thread about the same crap that happened to me. rear was silent untill some track passes and then it was whining and leaking turns out the pinion nut backed out so he replaced the seal and reset the preload and he was fine, hopefully thats my problem. So we will see. i replaced the axles bearings and seals so i know they are good. anybody know if strange uses a crush collar on their rears or if they use a solid spacer. Im going to call them but just checking if anybody knows. thanks for the feed back guys ill keep you guys posted!

WildBillyT · 08-01-2010, 05:42 PM

For what it's worth:

Plenty of guys do what you do on 12 bolts with no issue. Many even go a lot faster on 12 bolts. I don't think it's the rear design per se but I'd take a hard look at the parts/labor that went in to it.

transmaro93 · 08-01-2010, 05:54 PM

^^ yea like i said above im now just reading about alot of quality control issues with strange rears so maybe i got a dud one... who knows either way the housing is good so if i have to rebuild it i will and ill know first hand that its set up good.

transmaro93 · 08-03-2010, 07:57 PM

these pics dont tell much but do any of you guys see anything wrong?

in this first pic you can see the discolor of the edge of the gear and the really smooth polished area of the differential and see how part of it is still roughly casted. is that normal for a eaton?

in this pic you can see the pinion has a really shiny part of the edge of the gear like it was riding on that. I dont know.

Now, i pulled both axles and both axle bearings are good (they were replaced when i had to change backing plates and are brand new). I borrowed a dial indicator from a guy at work that was missing a locking piece and trying to rig it to work but it wasn't giving a good reading so im going to have to get one but just checking it by hand id say the back lash is set pretty good, but again i don't have a reading yet. the pinion is leaking but i checked the nut and its still pretty tight in there enough that i couldn't loosen it with a ratchet (i read stories about people having it come loose and being able to turn it by hand). Any thoughts. Also it seams no parts stores carry that compound that you spread on the gears that allows you to check the tooth pattern. Is there anything else i can put on there that wouldn't hurt the rear. anti-seize or something like that? i donno nobody has that crap!

transmaro93 · 08-07-2010, 11:27 AM

quick update for anybody that might be able to help... I got my Dial indicator in yesterday at work and checked the back lash. Its set somewhere in between .009 - .010 which from what i read is right where you want to be for a 12 bolt. I checked the gear pattern with red wheel bearing grease because i couldnt find that gear compound anywhere and judging by that it looks like the gears are almost making a full tooth contact which is telling me that maybe the pinion depth is off. I have pics of the tooth contact if anybody thinks they want to help. Im going to call strange on monday now that i have some info to give them and see what they say. They are closed on the weekends. Thanks for any help. again the pinion has zero in and out play and no up and down play in the bearings...

Troy · 08-11-2010, 09:45 AM

Hey- Post up some pics of the contact pattern. When you originally set it up, your backlash was supposed to be .010 as you stated but once you've worn things in, your backlash can increase by a few thousandths which will cause your pattern to look different after some hard use. This happened to me and I had to add in a few thousandths to get the pattern back. An increase in backlash can also cause more gear whine (from my experience). I wonder if your pattern was originally setup at .010, maybe it was less. It also depends on where you are placing the gauge on the gear of the tool. I've messed with this and have seen that depending on where you put it, you can alter the backlash reading by a few thousandths.