squealingtires

iTrader: (14)

Can we have some discussion about the destructive forces, and modes of failure within a rearend differential. Sketches would also help out too. Could we limit our discussion to "weak" sections of a rearend, which tend to fail/flex/move/whatever and ultimately lead to catastrophic failure. The 10 bolt would be a great example for pointing out weaknesses? Perhaps someone could develop a failure tree of the rearend and walk us through how the torque from the input shaft eventually leads to failure.

CTSmechanic

iTrader: (2)

The componets are simply too small you'd be wasting your time and money trying to make something work with 7.5 parts.

98FiveSeven

iTrader: (1)

CTSmechanic is correct, the Ford 9" is massive so to speak especially compared to the 7.5 in the F-bodys. Honestly You have the same size gear and differential in an S10/Blazer that you have in a 320+ft lb tq car that will be abused. A very big limiting factor. Increase the Size, Increase the Strength. Like she always says guys bigger is better

BJM

iTrader: (1)

I for one would like to see some actual discussion on this. There are far too many pat answers stating that it is a waste of time to build a 7.5". Everyone agrees that a Ford 9" is huge and strong. Let's not waste time on that argument. Besides, it has a huge hypoid distance causing it to waste a lot of energy

I would like to hear more about case flex. It seems unlikely that the gears themselves are to blame. If they are inadequately held in place and are allowed to separate under load they will lose teeth. Furthermore, who is blowing up their rear ends, is it people with stock gears (ie set up by GM) or people with replaced gears (ie aftermarket set up the gears, possibly incorrectly). Lack of carrier preload (most people give little credence to needing to take a lot of care or measurement of it) could be killing a few of them.

MeentSS02

iTrader: (11)

I think you'd really have to look at what kind of stresses the torque arm mount induces on the housing...that's most likely where your answer will be.

jamesbtri

Come on Guy ...........This post is interesting dont stop there. He makes a great point with case flex. Lets keep this rolling see where it ends. There had to be a something that can be done.

Viper

iTrader: (6)

Also, there are people who live with the 3:42 stock gears just fine, even under the stress of 400+ ft/lbs. of torque. I built mine in 2002 with a T2R differential and solid race pinion, TA cover with preload bolts. 1.91 60 fts. and numerous HARD gear changes from 1-2 and 2-3. I've been to the 1320' probably 75 times on this combo and numerous autox. It lives.

I also know (or read on this board) of others who break them leaving a parking lot.

For me, I think the T2R diff made the difference.

Jpr5690

iTrader: (13)

I Think Your Tires Tell The Story... If You Drive On Areal Sticky Tire All The Time It Leaves All The Stress On The Spider Gears.. While Having Shitty Tires To Act As A Fuse Prevents You From Destructing Your Rear...

In Any Case I Just Ordered A Dana 60 Setup After My Fully Built 10 Bolt With An Auburn Race Posi Lasted Me 10 K Miles

squealingtires

iTrader: (14)

From what I've found about the 10 bolt failures is that most end up with stripped pinion gears and the ring gear teeth ends up chipped too. Drawing some possible conclusions, is it evident that the pinion shaft deflects more than the ring gear? I find it unlikely that the ring gear deflects much. Breaking it into 2 systems: .1 Pinion Gear; 2. Ring Gear these systems are tied back together through the casing.
1. For the pinion we have possible deflection in the pinion shaft and pinion support-->housing

2. For the ring gear we have deflection in the ring gear, carrier, main-caps, and housing

Does anyone have specs on the pinion shaft diameter between the 10 bolt and 12 bolt? I'll bet the weakness of the 10 bolt is in the housing itself as stated before and its ability to resist deflection under high torque loads. If this is the case I believe a great deal of strength could be added to the housing by adding truss supports. Many off road truck owners with with big tires and ultra low final drive ratios in the order of [(70-100):1] truss their axles (then there problem becomes breaking axle shafts!)

Jpr5690

iTrader: (13)

Spider Gears Are Too Small And Wear Out Quick.. Also The Ring And Pinion It Self Are Also Small...anyone Wo Has Actually Looked At A 7.5 Inch Diff Then Looked At Any Other Diff Can Quickly See The Thing Is Way Way To Weak.. I Dont Think Most People Have Problems With The 28 Spline Axles Or The Housing, As A 10 Bolt With A Spool Is Plenty Strong For Most 11-10 Sec Cars.. But With The Limited Space You Cant Pack Enough Material In Side That SMall Diff To Allow For Much Reliablity

MeentSS02

iTrader: (11)

Most of the 10-bolts that I saw get destroyed while I lived in Florida were due to the Posi blowing...I think I also recall someone breaking some 3.73s in an A4 leaving the line on nitrous. Not sure what happened there, but I don't think it was posi-related in that case. Seems like there are a few too many variables in this one...

My gears from GM came set up noisy as hell, and it took them 4 times to set them up right. Unfortunately, there is now a great deal of play between the ring and pinion - you can turn it about 5 degrees or so before one contacts the other (might be exaggerating, but it is a lot more than I think it should be). This rear has held up to my sticky clutches, but I've never run sticky tires. The rear is now starting to make some more noise (whining, clicking, etc), but is still holding in there.

CTSmechanic

iTrader: (2)

When GM drew up the 7.5 they did it for as cheap as they could... They didnt even worry about folks like us beating the hell out of them....Unless your going to have pay the money and have some custom parts made or or go to any other lengths to try save the 7.5 your wasting your time in my opinion.You have to know when to hold'em and when to fold'em....Like everyone knows there are many many options avalible.People on this site worry about some stupid stuff.. who cares how much power a 9 inch takes.... or how much a Dana 60 weighs... if they'll let you get down the track faster and more consistent then its a gain.

themadspoon

iTrader: (7)

Most failures i have seen in the 10 bolt have been the posi going out. That was the case with my last 10 bolt it just shattered the spider gears.

squealingtires

iTrader: (14)

Has anybody ever put a spool in a 10 bolt?

Candyredz28

iTrader: (4)

I had a 85 Monte Carlo SS with a 400hp 350 and welded spider gears for about a year, also with slicks and it never broke.

SSwanner

iTrader: (128)

my old 10bolt lasted for a little less then 2 years before the posi split. it cracked in the middle & sheered 2 of the 4 bolt heads off that bolt it together. my dad is an ASE mastertech & built it for me with a set of OEM 3.73's. it was built right & never made a noise of any kind. i ran redline lightweight shockproof fluid in it also.

i had the stock cover too. i know it had a minimum of 250+ track passes with 1.52-1.80 60's on it, i launched it off the transbrake on the kit more times then i can remember. when it broke i had just had the 370 tuned on the kit which did 510rwhp through the th400. after it broke i sold the ring & pinion and axles which were still in good shape.

a lot of the failures i have seen are with aftermarket gears. i've seen 2 of them with 4.10's that broke & i know they were not installed correctly and sounded like a 2 yearold screaming.

The Butcher

Any body ever tried an 8.5" GM 10 bolt? I'm tryin to decide on building mine, or droppin two and a half G's on a 9" I don't see a half inch difference (1/4 inch each direction) bein worth that much.

BJM

iTrader: (1)

Has anyone got a CAD drawing of one of these axles? Preferably an IGES or STEP file. I would make a finite element model of it for fun to see where all the loads go and what distorts the most.

ezrollin

I put my 4.10s and ZT in myself
I didnt know the pinion nut was supposed to be 150ft/lbs which is a bit.
After a year later it slowly gave away (I knew it was cause of the screaming)
then I took a turn and it all fell apart. shattered teeth and cut up my ZT.
Now I put the 3.42s back in and its going good

gun5l1ng3r

Is Finite Element Analysis where you can put in material strengths and specifications and see how they act in real world conditions?

And do you know why is is called Finite Element models?