project family wheeler. chop top 1 ton explorer.

[freckles]

Yup, but you don't even need to worry about using studs. Just conter sink the cover and use some grade 5 or better bolts.

Just to be a nerd (an early, after Christmas Morning Nerd, so my math is probably off)...



Cliffs: I got a little wordy early in the morning, but if your diff cover has at least 2 grade 5 bolts holding it on, they're not going to get sheared off.


.....Math below....

Shear load failure is figured at 60% of thetensile strength (Grade 8 is 120 ksi, and Grade 5 is 85 ksi).

So you take the area of the fastener (we'll assume 3/8" bolts) A=Pi*R^2 so that A = 3.14*(.1875)^2... A=.1104 sqin for a 3/8 Bolt.

60% of 120 ksi (proof load) = 72 ksi. (Grade 8)
60% of 85 ksi (proof load) = 51 ksi. (Grade 5)

So the Capacity in Shear for one 3/8 Grade 8 bolt = 72 ksi * 0.1104 or 7,948 lbs woth of shear per bolt. Grade 5 is 5,630 lbs per bolt.

Now figure the pressure of the ram, we'll use a Huge 2" Ram with the a maximum rating of 3,000 psi (most PS pumps put out around 1,500 - 1,800 psi max).

Ram Force = Ram Working area * Applied Pressure
Ram Force = 3.141 * 3,000
Ram Force = 9,243 lbs

Figure in 10 bolts per cover or so, and you've got a pretty healthy safety margin there. The only thing I would be worried about is that cover getting worked lose over time. With counter sunk holes, RTV, and properly toqued bolts it a non issue.

If my math's off Its good enough for this

Nope, your math's dead on. I was thinking of the loose cover capscrews I've tightened during oil changes when I suggested studs. THEN, you could use nyloks and secure the bugger, once and for all. After all, the 'loose' bolts seem to work from one to the next when they start to loosen. Imagine the carnage if (un-caught) loosies came undone and either dropped out or sheared on a hard right with the tire against a big-ass rock.

And you wouldn't just want the bracketry out of the way for a gearset change. It'd be nice to have it open when you break a diff and have pieces to clean out and replace with something stronger. Like I said, I've been into a few of these and there's no good way to get them out if you can't pry the gearsets out or use the spreader to widen the case a skosch. A big, strong bracket would very possibly be right exactly where you need to put the heel bar.

But I guess there's always the air-arc...


freckles

 

[Kage]

This...

My head hurts

Its like Magic I Tells ya!

Thats alot of math

have you used those formulas to find out how much force it took to shear off your highsteer arm studs?

Fawker FWIW, those arms sheared off because the top of the knuckle was never machined flat. So those were doomed to fail at some point since I failed to notice the error. Somone did do a decent looking job with a grinder to get it flat the first time.... Well decent looking until you put a straight edge across it

Ok Ben, who did you copy this from
SVT

I've got an odd background, and I now work with a bunch of Metallurgist, so that doesn't help anything either

... Imagine the carnage if (un-caught) loosies came undone and either dropped out or sheared on a hard right with the tire against a big-ass rock. ....

While I've never seen cover bolt failure (I'm sure its out there), I would hope that it would be obvious that things are starting to go south. Best guess is that it would probably dump all the gear out out first before it sheared off the bolts. Unless you've got my luck, then it wouldn't be a nice neat shear, it would more like WW3 happened on your junk

Who brought the math in here, there will be none of that shit in here!
Because I suck at math

Put up some progress photos (Hell, just make a video of you sitting in the drivers seat making motor noises), and I'll keep the math away. Deal?

 

[Bray D]

That math works, in a perfect world. Real life scenario - the bolts are not loaded in perfect shear, bolt circles are not perfect, holes are not perfectly round, etc.

What I'm getting at, is all of the load COULD be transmitted to one bolt, which if grade 5, could fail, resulting in the failure of the adjacent bolt, and its adjacent, etc. Zipper style failure. It happens more likely than one would think.

One thing you also didn't take into account (which would help your argument) is the clamping force of the bolts, coefficient of friction between the cover and the housing, and the resulting friction force that would have to be overcome before the bolts take ANY shear load.

Mounting the ram to the cover will work, and is done frequently in the offroad industry. Mine will most likely end up being mounted to the cover as well.

I'm just throwing out some food for thought.

 

[86 slo-vo]

I did just order some leaf springs

I've got a set of rancho 44044's coming and next week I should have something else a little more interesting coming to try out......

I've been reading about them for a while and it's time I try them.

http://www.liquidironindustries.com/product.php?productid=17611


And BTW if you guys only knew how much seat time I've already had, I've been in there banging gears since I started

 

[Kage]

...(Bray Said Stuff)...

Now you're just nerding up the thread How you liking that spool in your truck?

... a little more interesting coming to try out......

I've been reading about them for a while and it's time I try them.

http://www.liquidironindustries.com/product.php?productid=17611

Ah good! I do want to hear your thoughts on how the slider boxes work out on the front with something that sees a good amount of road time. I strongly thought about going that route, but chickend out because I couldn't find any long term reports on how well they work out on the road. Plenty of folks running them in the rear, but it seems like few people run them in the front, and on the road.

Now go back and make a few more motor noises

 

[kroussinoffroad]

now those are pretty slick.

 

[86 slo-vo]

Now you're just nerding up the thread How you liking that spool in your truck?



Ah good! I do want to hear your thoughts on how the slider boxes work out on the front with something that sees a good amount of road time. I strongly thought about going that route, but chickend out because I couldn't find any long term reports on how well they work out on the road. Plenty of folks running them in the rear, but it seems like few people run them in the front, and on the road.

Now go back and make a few more motor noises

I'm planning on them front and rear, my first thought was for the rear so I could run the Chevy 63's and French the mounts into the frame so I could keep it low but the more I read about how stable they are I figured it would be worth it to run them all around.

 

[86 slo-vo]

This is the plan.

 

[Robert_1967]

And BTW if you guys only knew how much seat time I've already had, I've been in there banging gears since I started

I can just see you sitting there making engine noises and leaning out the door to see if your clearing that tree and big rock




Robert

 

[86 slo-vo]

No comment........

 

[kroussinoffroad]

hahaha the other night there were 3 people in mine makin engine noises, had to be a fuddy duddy and put the kibosh to it cuz they were gettin way outta controll. they were catching air,doing massive burnouts bangin gears etc etc truly put and end to it tho since it is on jackstands and they were really shackin the thing.

 

[--weezl--]

That math works, in a perfect world. Real life scenario - the bolts are not loaded in perfect shear, bolt circles are not perfect, holes are not perfectly round, etc.

What I'm getting at, is all of the load COULD be transmitted to one bolt, which if grade 5, could fail, resulting in the failure of the adjacent bolt, and its adjacent, etc. Zipper style failure. It happens more likely than one would think.

One thing you also didn't take into account (which would help your argument) is the clamping force of the bolts, coefficient of friction between the cover and the housing, and the resulting friction force that would have to be overcome before the bolts take ANY shear load.

the first part is a very good point, and the last paragraph made me think here... if a bolt has (for arguments sake, lets use a round number) 100lbs tensile strength, it would have 60% of that as sheer, ok, so 60lbs sheer strength, but they don't really compound... so that being said... lets say for instance, that the 100/60lb limits were actual breaking limits... if you were to torque the bolt so that there were 99lbs of tensile pressure on the bolt, you cannot put much of any sheer force on the same bolt. basic math would imply that if you were to put 0.6lbs of sheer force on it, it would fail, however, to me, i would think it would take more than that... that being said, the 60lb normal sheer limit is not accurate with compounded stress...

in other words, if you want to do it by the book, for every lb of tensile pressure on the bolt, the sheer limit on that bolt should be lowered by 0.6 of a lb (60% threshold)

ie, the torque specs for a ford 8.8 are around 33ft/lbs? i'm going to guess with the ram mounted to the cover, it's going to be closer to the 50ft/lbs... with that, that gives us a clamping force, or tensile load, of about 660lbs (based off of 3/8" bolt) now subtract that from the 9300lbs of tensile strength that Kage calculated, that gives us 8640, of remaining tensile strength, multiply that by .6 (60%) gives us 5184lbs of available sheer pressure before the failure point

here's where i lose it a little, maybe, and start guessing:

Kage, i assume you mean that by ksi, you mean kilos per inch^2? and by that the 5184 is psi, based on the fact that the cross section of the 3/8 bolt is just that, 3/8, (measuring from the outside of the threads, which do not help the strength at all) we should be able to multiply the 5184 by .375, to give the actual sheer point of of 1944 axial lbs... now that being said, the initial sheer won't be the perfect fit (hole for bolt) there will be a % of loss here, but lets ignore that...

 

[4.0B2]

um...
we need more pics of the build
screw this math/technical/ in theory crap..

 

[--weezl--]

my point still stands, why mount to a removable part, when you could mount to the tube, or pumpkin by moving it an inch...


PICTURES!!!!!!!

 

[RangerSVT]

Additional brackets and tabs to mount and brace and reinforce...Besides, in theory, these figures would go somewhere, but in the real world in applicable situations, This setup has been done countless times with very minimal failure occurrences...
SVT