stock rear diff 1,000?

J

jpalmer

New member
NO, i am not making this power. But for reliability reasons, can our little rear diff stay alive for long with this power?!?!

Anybody using a spool?

What axles are a good upgrade?

What C-clip eliminators to run?

Part numbers would be good.Opinions are fine, but i prefer experience.

I know it is not ideal to run a tiny 10 bolt, but lets be real, i have seen single digits ran on them using awd.


i have ran a spool on the street, not a awesome experience, but in a strait line, it flat out works. Not to mention cheaper and more reliable.
 
AceHaag

AceHaag

Member
Re: stock rear diff 1,000?

With sticky tires you will twist the axles off at the splines. they are just too small to handle the force. If you bumped it up to a 30 spline axle some how then you would have to worry about twisting the pinion off. those are the weak links in the 7.5 rear.
 
DaveP

DaveP

Active member
Re: stock rear diff 1,000?

A: We have a 7-5/8 rear, not a 7-1/2. There is a difference.
B: We have AWD. The rear only receives 2/3 of the total power produced. I feel this is the key element as to why our rear diffs are relativity trouble-free even in low-12 SyTy's.
C: A little "quick math". I don't know how much torque is represented at the diff by 1,000 HP, but a stock TBI 4.3 produces about 200 FtLbs. Multiply that by 3.07 1st gear, and 2.42 LoRange T-case ratio, then reduce by 50% because 1/2 the torque goes to the front in 4X4, and you still have 743 Ft Lbs at the rear diff. That's a LOT, and the 7-5/8 diff seems to have lived long lives in millions and millions of T-series 4X4's.

I saw a very intriguing rear axle in a 95-ish Grand Cherokee at pick-a-part yesterday. An aluminum center Dana 44 with rear disc brakes. I didn't measure the flange-to-flange, but it looked about right, and to replace the coil spring mounts with spring perches is fairly straight forward. Only pitfall is that I don't believe a 3.42 ratio is available for the Dana 44. (Tag on this one said 3.73). Closest is 3.54. But it was interesting.
 
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blacktyaffair

blacktyaffair

Donating Member
Re: stock rear diff 1,000?

DaveP said:
A: We have a 7-5/8 rear, not a 7-1/2. There is a difference.
B: We have AWD. The rear only receives 2/3 of the total power produced. I feel this is the key element as to why our rear diffs are relativity trouble-free even in low-12 SyTy's.
C: A little "quick math". I don't know how much torque is represented at the diff by 1,000 HP, but a stock TBI 4.3 produces about 200 FtLbs. Multiply that by 3.07 1st gear, and 2.42 LoRange T-case ratio, then reduce by 50% because 1/2 the torque goes to the front in 4X4, and you still have 743 Ft Lbs at the rear diff. That's a LOT, and the 7-5/8 diff seems to have lived long lives in millions and millions of T-series 4X4's.

I saw a very intriguing rear axle in a 95-ish Grand Cherokee at pick-a-part yesterday. An aluminum center Dana 44 with rear disc brakes. I didn't measure the flange-to-flange, but it looked about right, and to replace the coil spring mounts with spring perches is fairly straight forward. Only pitfall is that I don't believe a 3.42 ratio is available for the Dana 44. (Tag on this one said 3.73). Closest is 3.54. But it was interesting.
Click to expand...

My C4 came with a HD Dana 44 with a 3.45 ratio and according to Randy's ring and pinion, the GC Dana 96-98 use the same part number ring and pinion as the C4 Dana. It's a little closer. Maybe the difference could be made up with tire size?
 
DaveP

DaveP

Active member
Re: stock rear diff 1,000?

blacktyaffair said:
My C4 came with a HD Dana 44 with a 3.45 ratio and according to Randy's ring and pinion, the GC Dana 96-98 use the same part number ring and pinion as the C4 Dana. It's a little closer. Maybe the difference could be made up with tire size?
Click to expand...

I forgot about that ratio in C4. It's an optional, special order, manual transmission ratio. I am not aware of any variances of D44 ring and pinions between the various D44 applications. . AFAIK all Dana 44 ring and pinions interchange. BWTFDIK.

My friend that was with me yesterday is a Jeep Guy and tire dealer. He said the Jeep guys don't like the aluminum center D44 for durability reasons. They tend to break when bounced on big rocks. He also thought the wheel lug pattern is 5 on 5. We need 5 on 4-3/4, but axles and rotors can be re-drilled. As I said, I was intrigued by this assembly. I feel it has potential.

Thanks for the edjumication on the 3.45 ratio.
 
BMFB

BMFB

Not to scale
Re: stock rear diff 1,000?

I know of at least 1 member on the board putting down some serious numbers on a stock rear diff equiped with only a locker. Still awd and full weight.
 
ed hess

ed hess

race or get outta the way
Re: stock rear diff 1,000?

The following video should make you stop asking questions about using this rear. lol

Notice the tire and axle assembly flying behind the truck as it comes out.

Nuff said.

http://www.youtube.com/watch?v=L3WQGiWpeBc

When changing out this rear noticed the housing was bent from the power being thrown at it.
 
fivetodrive

fivetodrive

CRISPY
Re: stock rear diff 1,000?

That is why any time I find a 8 1/2 rear I grab it even if it dosent have axles, like the one I have now. If you need one maybe I can find another...
 
ed hess

ed hess

race or get outta the way
Re: stock rear diff 1,000?

5678TA said:
X2!! that will save your brakes(assuming rear disc), cladding, bed, and wheel/tire in the event of axle failure.
Click to expand...

actually fyi, having tested that rear for breakage events I can tell you:

The cladding wont touch the ground as the backing plate supports the wieght pretty well.

Tires and wheels come thru without damage.

However if the tire comes back at the truck as you do a 560 degree spin you might get a rub mark on the front bumper. Tire rub marks polish off nicely.

However you will scare the piss out of the guy in the other lane, bend his door in on his mustang a bit. But fear not as the taillight lense that pushes his door in by rubbing his body side molding will only have a little plastic residue that you can rub off easily. ( I left mine on due to it being a cool story - battle bruises) lol
 
autoaddictions

autoaddictions

Active member
Re: stock rear diff 1,000?

I blew my diff on drag radials at the 700 hp mark. I slapped another stocker in there But its a time bomb for sure. Im upgradeing to the 8.5 rear. I did make hundredes of passes in the low 11s with no problems. Once i made it into the mid 10s there rear was a danger. 1000 hp not going to make it very long if even on pass.
 
ed hess

ed hess

race or get outta the way
Re: stock rear diff 1,000?

autoaddictions said:
I blew my diff on drag radials at the 700 hp mark. I slapped another stocker in there But its a time bomb for sure. Im upgradeing to the 8.5 rear. I did make hundredes of passes in the low 11s with no problems. Once i made it into the mid 10s there rear was a danger. 1000 hp not going to make it very long if even on pass.
Click to expand...

I agree with frank on the time bomb... ya know I like this new 9inch fabbed rear hooked up to the 4 links, especially with the 33x10.5's and 16x16 double beadlocks.... now that's badass.
 
J

jpalmer

New member
Re: stock rear diff 1,000?

I did mention c-clip eliminators in my first post, this should keep an axle from coming out.


Dave, an aluminum section 44 would be awesome if a gearset could be found.Part of my concern is that not holding that much power and spending money on something that won't last. But same goes for our 7 5/8. How much did they want for the diff? :http://www.precisiongear.com/dana44.htm

What is another viable choice? 8.5 sounds like it would be beefier, maybe a 12 bolt. My concern is budget, although budget goes out the window as soon as something breaks and you have to buy new again or upgrade then. On the other hand, people have had them live for a while without breaking at high numbers.
 
V

vmack

New member
Re: stock rear diff 1,000?

I think a zq8 truck has a 8.5 I there a rear out there that will fit right in as a upgrade?
 
DaveP

DaveP

Active member
Re: stock rear diff 1,000?

vmack said:
I think a zq8 truck has a 8.5 I there a rear out there that will fit right in as a upgrade?
Click to expand...

Bzzzt. ZR2 has the wider 8.5. ZQ8 is shock absorbers and wheels. not much else. Certainly not an 8.5
 
C

Captain Morgan

Moderated User
Re: stock rear diff 1,000?

there is an 8.625" out there too.

I'm not 100% sure on the ZQ8 rear being an 8.5", if that is true, its probably only behind 4.3L 5-Speed trucks. Also, I don't think it would be a direct bolt in, since a 4x4 ZQ8 does not exist, but it could be narrowed, but at that point you could explore other options as well.
 
Beavis

Beavis

Still plays with trucks
Re: stock rear diff 1,000?

I thought the manual trans ZR2 rear ends were the biggest/strongest? Only problem is the width, like 4 in wider than a standard 4X4 like ours....but cut it down, add in better axels and c-click eliminators.............
 
fivetodrive

fivetodrive

CRISPY
Re: stock rear diff 1,000?

This comes up a lot and the non zr2 4x4 5 speed from 95 or so and up drum brake rear
end is a direct 8.5 bolt in with a 3.42 "posi"

I did see a post on a s10 site that on the disc brake rear's you can use the 8.5 2wd housing with 4wd brakes to get the correct width but I have not confirmed this.
 
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