Grenaded my rear end!

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Agent_Orange

Agent_Orange

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Had a crappy 7.25 rear end in my duster and grenade it last night doing burnouts.

I have an A-body 8.75 housing and 2 center sections at home that both need completely rebuilt. one is a 741 and the other is 489.

whats the difference between these center sections? which is better for street use

how do i tell if i have a sure grip?

Neither center section has a ratio that I want so i will need a ring and pinion set. what are good brands?

what other parts will i need

i have never had a rear end apart. any tips?
 
Dont know much about 8.75 but a sure grip is easy to see the clutches in the center section. Look like trans friction plates.
 
Either case is ok. 489 has a stronger pinion. Just look for 'clutch' mechanism vs just spider gears to know if it's sure grip. For general street/driver use, I've had good luck with Yukon gears. Read up a little, rear ends are pretty straightforwad..
 
741 has the Smallest Pinion shaft. Still a Strong case though.

489 uses a Crush Sleeve, Which from what read can be a Pain. So you can buy a Crush sleeve eliminator. And i think more parts are Available for the 489 and 742 Case's.
 
limegreen70 said:
741 has the Smallest Pinion shaft. Still a Strong case though.

489 uses a Crush Sleeve, Which from what read can be a Pain. So you can buy a Crush sleeve eliminator. And i think more parts are Available for the 489 and 742 Case's.
Click to expand...

Everything I've bought for 8.75 comes from Cass at Dr Diff. He is very helpful and sells good parts at reasonable prices.
 
Wisest advice I ever heard is that if you have a 7 1/4, don't even drive it PAST a dragstrip.
 
Here's a handy guide on rear ends: Mopar Casting Numbers - MyMopar.com - Mopar Part Numners

Here's an open rear end:
323abodybuild-3.jpg


Here's a clutch style:
0311001325-small-jpg.2424


Notice the springs and such in the middle. There's also a cone style. But that's how you tell a sure grip from an open unit.

If you need gears I got a set of 489 3.55 gears. Motive - C887355L. 29 spline.

3.55 gears are a great "middle" gear. Good for streetability and for highway driving. Anything into the 4's are more drag/street gears. Anything higher into the 3's is more highway.
 
Lustle said:
Here's a handy guide on rear ends: Mopar Casting Numbers - MyMopar.com - Mopar Part Numners

Here's an open rear end:
323abodybuild-3.jpg


Here's a clutch style:
0311001325-small-jpg.2424


Notice the springs and such in the middle. There's also a cone style. But that's how you tell a sure grip from an open unit.

If you need gears I got a set of 489 3.55 gears. Motive - C887355L. 29 spline.

3.55 gears are a great "middle" gear. Good for streetability and for highway driving. Anything into the 4's are more drag/street gears. Anything higher into the 3's is more highway.
Click to expand...

That is a CONE style sure grip.

This is a clutch style

003.jpg


Easy way to tell. The bolts holding the two halves together. On a cone style, same side of case as ring gear bolts. Clutch style on the opposite side of case.

The rounded step down and visible springs on the cone are other identifiers.
 
crackedback said:
That is a CONE style sure grip.

This is a clutch style

003.jpg
Click to expand...

Oh yes. I got them backwards. Whenever I see springs I think of clutches for some weird reason...

In any case. Some people have their preference as to which. Either work well as far as I've ever found.
 
there is also a cone type suregrip unit that does not have clutches, it has 4 springs. I like Strange/US gear - made in USA. I don't think the aftermarket makes gears for the 741
 
...and I'd not call swapping gear sets "easy" unless you have dial indicators and know how to use them, not to mention spanner wrenches.

Definitely not a beginner level task.

Not terrible, just takes attention to detail and patience.....and those tools.
 
So it looks like I have 2 options.
1. Find a local guy to do the 8.75 build for me
2. I have a complete b-body 8.25 out of a police car. I would just need to move the spring perches in something like 1/2 inch.
 
What year B body 8 1/4?
 
1970 is possibly doable.

1971 and newer is too wide.

Find a 66/67 8 3/4.

No mods (unless you're anal) and probably under $200.
 
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