8.75", ford 9", dana, oh my! :)

[defiance]

I thought I'd come to a decision on my rear end, but I mentioned my plans in passing in another thread, and it spawned quite a bit of discussion - since that was in the chassis/suspension forum, I thought I'd come here before I go too far down that conversation

Anyway, I've got an 8-3/4 with a nasty-high gear ratio right now.  'The locals' are suggesting I get a cheap & easy ferd 9" or 8.8" - both of which are readily available locally for next-to-nothing, and the 8.8 has discs.  Admittedly, even though a bit of fab work would be necessary (not much as far as I can tell), $100 for a rear end with the gears I want and discs is *RATHER* tempting.

Compared to what I have now - the 8-3/4 is (from my understanding) comparable in performance and reliability with the 9" ford.  Now, I know we all love Mopar, and I love her too, but from a pragmatist viewpoint, $100 for discs and proper gears, vs. nearly $500 for rear disc brake kit, and $300 or so for a rear center section for my 8-3/4...  I really don't care about stock, I'm just concerned about best performance (and saving a few bucks doesn't hurt when I can). 

So as far as that goes, is there any other reason I haven't thought of why I should stick with the 8-3/4?





Having said that,  that whole discussion may be completely moot.  I know I'll be past 600hp, and probably around the 700 mark, when it's all said and done.  It's not a 4-speed, so that's a plus, and I won't be transbraking, but I do plan on seeing the strip a good bit.  So, I'm afraid the 8-3/4, 8.8, or 9 will all suffer imminent death...

So I start asking around locally about recommendations for better setups (expecting to hear about Danas), and I hear several people saying I need a "Grand National" rear end.  I ask if they mean a rear end out of a grand national, they say no, that's different...

I've never heard of such a thing...  Are these people pulling something from inappropriate orifices, or is this something I need to look up?  All I can find from google is the buick stuff...

Anyway, failing all the above, I must consider Danas.  Sure, I know they'll take the power, but man what a price tag those things carry.  New, or rebuilt, I'll be VERY lucky if I got away for less than 2 grand. 
Chryco suggested that I look for 3/4 ton ford/dodge pickup trucks.  Ok, I'll start digging - but somehow I'm thinking it's not going to be that easy...  what would be necessary to fit such a vehicle to my car?    I know relocated perches, which my dad has actually done on all the cars he's transplanted ferd 9's into, so I can recruit him there.  What else, though?  How can I get away from the 8-bolt pattern that's sure to be on them?

[defiance]

Incidentally, if an 8.75 *will* hold up, is this the kind of part I need to be able to do a couple-hour backyard swap?

http://cgi.ebay.com/ebaymotors/Mopar-8-75-8-3-4-suregrip-posi-3-23-489-housing_W0QQitemZ220048432078QQihZ012QQcategoryZ34208QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

[Silver R/T]

go for it

[Chryco Psycho]

you need to cut off the floater ends & have them replaced with car ends then  have the housing narrowed  & order new axles
we went to the wreckers on sat & bought a Ford 3/4 ton diff with 3.73 ratio & sure grip for under $100  with the rest of the work we will be around $1000 total
BTW there was at least 3 more to chose from there 

[is_it_EVER_done?]

Defiance, I have never heard of a brand called Grand National, so I have no idea what your friends are referring to, but for your plan of 700+ HP/TQ in a heavy Charger, that you plan on running at the strip (slicks), you can forget an 8-3/4 as you won't get it to live for long without spending more on it than any other choice.

A 9 inch with a Nodular case and aftermarket axles should work without any problem, but I have no idea what the final cost would be, as it generally costs as much or more to build a 9" as a Dana.

I have no experience with the Ford 8.8, but I'm guessing it would never hold up, otherwise, at 100$ complete, it would be more popular than naked supermodels.

A Dana is going to be your best choice. If you have the fabrication skills and time you can build one from a truck core, but the Strange S-60 is around 80+ lbs lighter than a "truck core" unit, and is much stronger/better as it is Nodular iron, and has adjustable carrier bearings. As you pointed out, your looking at about $2,000 with a Power-Loc posi, but if you really do build 700 HP, it will be among the cheaper mods necessary to contain that much power in racing conditions w/a 4000+ lb car.

[rt green]

i agree

[Steve P.]

Defiance, I have never heard of a brand called Grand National, so I have no idea what your friends are referring to, but for your plan of 700+ HP/TQ in a heavy Charger, that you plan on running at the strip (slicks), you can forget an 8-3/4 as you won't get it to live for long without spending more on it than any other choice.

A 9 inch with a Nodular case and aftermarket axles should work without any problem, but I have no idea what the final cost would be, as it generally costs as much or more to build a 9" as a Dana.

I have no experience with the Ford 8.8, but I'm guessing it would never hold up, otherwise, at 100$ complete, it would be more popular than naked supermodels.

A Dana is going to be your best choice. If you have the fabrication skills and time you can build one from a truck core, but the Strange S-60 is around 80+ lbs lighter than a "truck core" unit, and is much stronger/better as it is Nodular iron, and has adjustable carrier bearings. As you pointed out, your looking at about $2,000 with a Power-Loc posi, but if you really do build 700 HP, it will be among the cheaper mods necessary to contain that much power in racing conditions w/a 4000+ lb car.

And there really isn't anything else to add.  Only one question. Are you planning to make 700 HP all on motor or adding N02? If you are going for 700 HP all on the motor, your money spent on the rear end will be the least of your worries.   If you go with a DANA, your rear end worries will never be worries again.

[defiance]

512 stroker, victor heads, modified EFI manifold (built from tunnel ram), girdle, etc - going all motor on it.  ...

Things like this, for me, I work out how much I can do with the motor given my budget, then I start thinking outside the motor and the budget goes out the window

I think I may just get the 8-3/4 chunk for now, don't change the brakes, then try to 'take it easy' launching for a while, until I have enough saved up for a new dana with discs.  I need about 2-3 months in addition to what was already planned to afford the dana; this way I'll be able to drive it during the meantime.  Plus, if I'm going to spend in excess of $1500 (after discs) anyway, might as well make it the $2200 or so it'll cost to get lighter, NEW parts.

Man, this car is going to take forever to finish...

I just need to keep my resolve.  It's going to be worth it.
Gotta keep repeating to myself..
NO SHORTCUTS
NO SHORTCUTS
NO SHORTCUTS

[hemihead]

I think what your friends mean by a "Grand National" rearend is a Franklin Quick Change that was used in NASCAR a long time ago.

[dkn1997]

go with the dana.  leave the fords for the chevy guys who cannot get a super duty factory rear. 

[Rayzor]

I dont know the full report on the dana 60s, but I spotted one in a 72 ford f100 half ton. It didnt have the full floating ends either. It just had the ford big 5 pattern and drum brakes. they wanted 75 bucks for it to if I pulled it. It also had 4.10 gears and track lock.

[Steve P.]

What are you, NUTS?? GO BACK AND GET IT.....

[Rayzor]

Next time  I go there I will toss a tape measure on it to find out how wide it is, as it may make a good swap for someone.  But if it has to be narrowed then your no better off then if it was a 8 lug rear.   

[Steve P.]

$75 for ANY Dana 60 is DIRT CHEAP.....

[Chryco Psycho]

especially with a track lock in it

[Steve P.]

NO DOUBT!!!!   GO GET IT.............

[Rayzor]

Dana 60s 70s 14 bolts etc fall off the trees around here. I bet I could get 5 of them free just between a few of my buddies. Lots of old farm trucks etc around here for the taking. I really dont need it, but if anyone is interested its at B&R pick an pull in Eugene OR. I asked a few questions and it turns out that the semi floating 60 came in the f100 fords from 67-73, its 59 1/2 inches end to end. Its a factory hybrid cross with a dana 44 so it has 1.30 dia axle shafts with 30 splines.

[d72hemi]

What is the difference between Floating, Non, and semi floating? what does it matter?

Dana 60s 70s 14 bolts etc fall off the trees around here. I bet I could get 5 of them free just between a few of my buddies. Lots of old farm trucks etc around here for the taking. I really dont need it, but if anyone is interested its at B&R pick an pull in Eugene OR. I asked a few questions and it turns out that the semi floating 60 came in the f100 fords from 67-73, its 59 1/2 inches end to end. Its a factory hybrid cross with a dana 44 so it has 1.30 dia axle shafts with 30 splines.

Would these work in a 71-74 b body, with relocating the leafspings, and different backspacing?

[Rayzor]

a full floating axle does not support the weight of the car but only handles the twisting force. This is done by a hub supported on both sides by bearings. a semi floater is were the shaft is supported on the outer ends having to bare the weight and twist of the car and motor. all things being equal a full floater would be the strongest of the lot. As far as fitting your car I would think it could be done if it was the correct width or close and you had the shafts redrilled for the right 5X 4 1/2 pattern.

[Steve P.]

Using a full floater in your CAR would be a total waste of everything. It will look like shit. Weight about 100 pounds more and you will never get anything good looking on them for wheels. Besides all that every single person that sees your car will point and laugh..



Quit screwing around and get the DANA. If you don't know what to do with it from that point, send it out to Dr. DIFF. He can certainly make it everything you will ever need.

[defiance]

Ok - I found a guy that wants to trade me a dana from a '70 model b-body (he's not sure what kind.. which I'm a bit confused about - but he's sure it's a '70 b-body -- Don't worry, I'll confirm it myself before I take that step) - for my old 440 - good thing I had that thing freshened up! 

Now, looking at the specs, my '72 8-3/4 is 57.8" wide, with 47.3" perches, and 12.35" nose.  The '70 b-body dana is 54.9" wide, 44" perches, and 13.47" nose.

So, I'll need to:
-relocate the perches on the dana rear end 1.65" further out on each side (no big deal, I think?)
-shorten my drive shaft 1.12" (again, no big deal, I think?)

Those two I think my dad and I should be able to handle no problem.  He's been putting 9" ferds under all kinds of stuff for years, so he's pretty good at welding.

The thing I'm not familiar with is how to deal with the width.  It's 1.45" shorter on each side.  Is that small enough that I'd be OK just being picky about wheel/tire backspacing, or am I going to need to modify further?

Thanks for talking me out of the other options - I kinda lucked into this dana, but I wouldn't have even been looking otherwise

[Chryco Psycho]

by using wheels with less back spacing you will be able to compensate without modifying the housing & axles

[dkn1997]

Ok - I found a guy that wants to trade me a dana from a '70 model b-body (he's not sure what kind.. which I'm a bit confused about - but he's sure it's a '70 b-body -- Don't worry, I'll confirm it myself before I take that step) - for my old 440 - good thing I had that thing freshened up! 

Now, looking at the specs, my '72 8-3/4 is 57.8" wide, with 47.3" perches, and 12.35" nose.  The '70 b-body dana is 54.9" wide, 44" perches, and 13.47" nose.

So, I'll need to:
-relocate the perches on the dana rear end 1.65" further out on each side (no big deal, I think?)
-shorten my drive shaft 1.12" (again, no big deal, I think?)

Those two I think my dad and I should be able to handle no problem.  He's been putting 9" ferds under all kinds of stuff for years, so he's pretty good at welding.

The thing I'm not familiar with is how to deal with the width.  It's 1.45" shorter on each side.  Is that small enough that I'd be OK just being picky about wheel/tire backspacing, or am I going to need to modify further?

Thanks for talking me out of the other options - I kinda lucked into this dana, but I wouldn't have even been looking otherwise

that's just a good excuse to go out and get some steamroller wheels/tires

[TylerCharger69]

For the record...I bolted a Ford rear end in my '69.....just a matter of relocating leaf spring perches and modifying the driveshaft,  not to mention you have to adapt the brake lines  (smaller diameter and fittings on the Ford)  Mine came out of a Mach 1

[Steve P.]

So why did you use a ford rear end??