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  #1  
Old 11-27-2003, 06:29 PM
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Default 8.75/ford 9" ?

will a ford 9" third member interchange with a chrysler 8.75???
  #2  
Old 11-27-2003, 07:46 PM
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NO! Different spline axles, different center line, bolt pattern wont match up, and besides the 3/4 carier is just as strong as the 9 inch center so why bother.
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Old 11-27-2003, 09:35 PM
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Quote:
Originally posted by dwc43
NO! Different spline axles, different center line, bolt pattern wont match up, and besides the 3/4 carier is just as strong as the 9 inch center so why bother.
Last year I was asking a lot of questions concerning the phord vs Dana. I went with the dana but something I was told about the 9" still puzzels me.

someone said that the 9" uses up more horse power. something about where pinion meets the ring gear. Is it true that the 9" uses more horse power and if so why?
  #4  
Old 11-27-2003, 10:08 PM
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Even though I am a Mopar guy through-and-through........

........there is NO WAY that a 8 3/4 is even nearly as strong as a 9" Ford.

BUT the 8 3/4 is a more efficent rear end........there is less power loss through it according to the many tests that I have read.
  #5  
Old 11-27-2003, 10:39 PM
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A 9" Ford take more power to drive than a Dana 60 because of where the centerline of the pinion gear intersects with the C/L of the ring gear. The Ford is lower on the ring gear and has more sliding friction. At about 4.30 or 4.56 ratio ( depends on who you ask ) the 9" and the Dana are about a push on power consumption (loss through the gears). Once you go lower than that (higher numerical ie. 4.88, 5.13, 5.38 etc.) the Dana 60 gets better and better, less power loss through the gears.

Ever heard the one about the guys wanting a 9" (or 8 3/4) so they can have "street" gears and "race gears"??? Even though it is simple enough, it is a pain in the a$$ to do it, besides the cost of another center section (about $1500.00) laying around. And who wants to spend an afternoon doing that??? Keep it simple.

And the 8 3/4 is as strong as a 9". The problem is no pro gears available, and a limited amount of GOOD posi units available. A 1/4 difference in ring gear diameter is picking the fly poop out of the pepper.


M.S.
  #6  
Old 11-27-2003, 11:10 PM
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Quote:
Originally posted by madscientist


And the 8 3/4 is as strong as a 9". The problem is no pro gears available, and a limited amount of GOOD posi units available.

Me thimks that you have indeed gone MAD........

IF what you say is true - that the 8 3/4 takes less power than the 9" to "power" - and it is just as strong ..???

Then WHY aren't people using them by the thousands these days?

And there have been "pro" gears available for the 8 3/4.

Limited supply of GOOD posi units?.......who cares?....most people in this market use a spool.

Your thoughts?
  #7  
Old 11-28-2003, 12:02 AM
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I would think people use 9" more simply because they are more common.

As for strength, I don't know. I've seen some of my 4X4 buddy's bust the 9" apart in way's I didn't think possible(like right across the casting! With more than one ccenter section!)

I've heard the 9" is stronger, but I doubt it's by much.

My thoughts
  #8  
Old 11-28-2003, 12:04 AM
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Default freebie

thanks. i just had the opportunity to get a free one from my brother in law if it would fit. i didnt have any info on the subject matter. i'll just keep what i got and change the gears out. maybe 391's. thanks a lot.
  #9  
Old 11-28-2003, 12:11 AM
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Quote:
Originally posted by dave571


I would think people use 9" more simply because they are more common.


BUTTTT the 8 3/4 was WAY more popular way back ..... when used in the lighter cars and dragsters....when the 9" Ford was not even being considered.
  #10  
Old 11-28-2003, 12:18 AM
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Default 8 3/4 vs 9in.

I wonder why, NASCAR only allows the 9 in rear. Could be something to it. I run both, the 8 3/4 in a 489 case, and the 9 in in a Lincoln versailes disc brake setup in my 34 coupe. I like them both. Just my opnion, and you know that everybody has one, too.
  #11  
Old 11-28-2003, 12:29 AM
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Nascar ??........how about NHRA Pro Stocks..????

Out of the top ten PS carz.......how many run a 9" combo ??

all TEN ??........
  #12  
Old 11-28-2003, 12:56 AM
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The 9" has several advantages over the 8-3/4", the nose bearing on the pinion is one, the ability to add or subtract pinion shims without pulling the pinion bearing is another, and the ratios available like from Bonneville to ag use is good too. All that being said I use the Mopar in the oval rig because of the axles and brgs. The 9" is a good oval diff if you spend some bucks on axles and brgs. The floaters are all 9" based.
  #13  
Old 11-28-2003, 03:33 AM
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the gear coverage of the 8 3/4 is decent itself........from 6.17 to 2.76.

I heard that there was a 2.41 built also....I am looking for one of those.

Anybody have anything like that?
  #14  
Old 11-28-2003, 11:21 AM
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Being at heart a Ford guy,I must say that rear-end strength between the Mopar 8 3/4 and the Ford 9-inch is basically a wash. Sure,the Ford would be stronger if it has a nodular iron carrier,Pro gears,blah,blah,blah. But very few Ford rear-ends came from the factory in this way.
Also,one must consider the vastly superior Timken axle bearings of the Mopar over the Ford.
In total,I must say that the 8 3/4 is the superior all-around rear-end.
If someone wants a Ford rear-end that is even stronger in most ways than the venerable 9-inch,consider the 8.8-inch rear-end. One reason for this is because the 8.8-inch shares some parts with the Dana 60/Chrysler 9 3/4.
Merely my two (2) cents worth (?).............................
  #15  
Old 11-28-2003, 11:25 AM
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Default Interchangability

To go off on a parallel tangent, I've heard that if you were to beef up a lil' ole' slant six even a little you'd snap the 7 1/4 rear. As the Turkey Day Hot Rod Run is in full swing and I may have the chance to find a bigger rear, do I need to find the entire rear, axles and everything? Or, if I just find the center section, can I use my axles, etc?

Back to you, Bob.

Dan
  #16  
Old 11-28-2003, 03:02 PM
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Quote:
Originally posted by ChallengerChuck



In total,I must say that the 8 3/4 is the superior all-around rear-end.


IF this is a TRUE and the rear end costs less to "power"(and I have never seen a test or opinion that differs)....

AGAIN then..............why don't all the Pro Stock boyz USE this RE instead of the Ferd 9" ?
  #17  
Old 11-28-2003, 03:40 PM
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Is no one allowed to have their own opinion anymore?
  #18  
Old 11-28-2003, 03:44 PM
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Don't most of them run chevy's too?

I don't think popularity is necessarily an arguement in favor of quality.

Otherwise we all need sb chevy's, comp cams, hooker headers, ford 9", in a gm body of some sort, with hei ign, ect. crager 5 spokes, yadda, yadda, yadda

9" are more abundant than 8 3/4 without question. It would seem to be the obvious choice for street rods and race cars.

I'm not arguing the strength either way, as I've seen both destroyed.
  #19  
Old 11-28-2003, 03:48 PM
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Quote:
Originally posted by FARGO318
Is no one allowed to have their own opinion anymore?
That's a good question LOL

Maybe we need to start a new thread to debate the issue!
  #20  
Old 11-28-2003, 05:26 PM
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Quote:
Originally posted by FARGO318
Is no one allowed to have their own opinion anymore?
Is no one allowed to ask questions of another person - to understand THEIR position and rational thinking .....anymore ??
  #21  
Old 11-28-2003, 09:48 PM
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Calm down folks. This went WAYYYYY off track... mr. b only asked if the FORD 9" pig would fit in a Chrysler 8¾" housing. He didn't want to know which was better and why.

The answer to the actual question is - No, the FORD 9" pig will NOT fit in the Chrysler 8¾" housin
  #22  
Old 11-28-2003, 10:02 PM
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Well then....WTH - we will start our OWN debate !!
  #23  
Old 11-29-2003, 09:53 AM
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Quote:
Originally posted by Mister Fiberglass
Well then....WTH - we will start our OWN debate !!
Does anyone have an opinion on how the Phord 9" compares to a Dana with Mark Williams components?
  #24  
Old 11-29-2003, 10:31 AM
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Quote:
Originally posted by Mister Fiberglass

AGAIN then..............why don't all the Pro Stock boyz USE this RE instead of the Ferd 9" ?
Simply because the Ford rear-end is more plentiful than the Mopar rear-end. And the reason that the Ford rear-end is more plentiful than the Mopar is because the Mopar was considerably more expensive to manufacture,with the aforementioned Timken bearings,etc.
A HUGE example of the scarcity of the Mopar 8 3/4 is the difficulty in obtaining one for any A-body.
I still contend that in design and engineering,the Mopar is superior to the Ford.
  #25  
Old 11-29-2003, 11:48 AM
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Default my rear end hurts. ha ha

changing the 2 gears out of an 8 3/4, what is involved. is it simple or very involved. shims, alignment, spacing and etc. i usually do all my own work but have never done this. what do you think?
wanting to install some 3.91 gears. thanks
  #26  
Old 11-29-2003, 03:03 PM
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Quote:
Originally posted by ChallengerChuck
Simply because the Ford rear-end is more plentiful than the Mopar rear-end. And the reason that the Ford rear-end is more plentiful than the Mopar is because the Mopar was considerably more expensive to manufacture,with the aforementioned Timken bearings,etc.
A HUGE example of the scarcity of the Mopar 8 3/4 is the difficulty in obtaining one for any A-body.
I still contend that in design and engineering,the Mopar is superior to the Ford.

Oh really now ??!!.....then all of the boyz that run PS are clueless?

Mopar carrier less plentiful? ....what ????? ......... scarcity for the A body ???.......what does this have to do with a CARRIER ???

We are not talking about an axle housing? WTF !! MOST all PS boyz make their own axle housing anyways.

Did C C have toooooo much of the bubbley-stuff for Thanksgiving ?? Hung-over....just a tad ?? !!
  #27  
Old 11-29-2003, 04:15 PM
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Re: my rear end hurts. ha ha

Quote:
Originally posted by mr.b
changing the 2 gears out of an 8 3/4, what is involved. is it simple or very involved. shims, alignment, spacing and etc. i usually do all my own work but have never done this. what do you think?
wanting to install some 3.91 gears. thanks
It's very involved. You need regular hand tools and a dial indicator to set up back lash and bearing load and a torque wrench for pinion load and bolt torque. If you have not done this before your better off getting a center with gear already installed or get some one to do it for you. If it's not right it will whine either all the time, or on decel or accel. And it will wear the gears out if it's not right.
  #28  
Old 11-29-2003, 08:55 PM
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Default Re: Re: my rear end hurts. ha ha

Quote:
Originally posted by dwc43
It's very involved. You need regular hand tools and a dial indicator to set up back lash and bearing load and a torque wrench for pinion load and bolt torque. If you have not done this before your better off getting a center with gear already installed or get some one to do it for you. If it's not right it will whine either all the time, or on decel or accel. And it will wear the gears out if it's not right.

Just out of curiousity, when setting the backlash, is there an upper and lower control limit (say like plus or minus a few thousands)?


Same question for the preload on the pinion. Does one have plus or minus a few inch pounds or will the gears wind if the backlash and preload are not set exactly on spec?

Once the ring and pinion are set, do you have to somehow check where the gears are meshing?

I have never set one, but have seen them done at the shop. Every now and then, I hear the guy say - it's close enough. I say to my self what the heck does "it's close enough" mean when he's playing with thousands and inch pounds.

Does it make a difference on the set-up if it is race only application compared to a street/strip car that may drive 3,000 to 5,000 per summer and fall/year.
  #29  
Old 11-30-2003, 01:08 AM
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Quote:
Originally posted by Mister Fiberglass
Oh really now ??!!.....then all of the boyz that run PS are clueless?

Mopar carrier less plentiful? ....what ????? ......... scarcity for the A body ???.......what does this have to do with a CARRIER ???

We are not talking about an axle housing? WTF !! MOST all PS boyz make their own axle housing anyways.

Did C C have toooooo much of the bubbley-stuff for Thanksgiving ?? Hung-over....just a tad ?? !!

1)No sir,I did not say or imply that PS guys were "clueless." I simply stated that from an engineering and design standpoint,the Mopar 8 3/4 rear-end was superior as a whole to the Ford 9-inch.

2)Yes,most PS guys do make their own axle housings. I did not know that this point was relevant to this conversation. Please forgive my ignorance!

3)No sir,I did NOT have "toooooo much of the bubbley-stuff for Thanksgiving"!!! In fact,I had none of the bubbley-stuff;I am a tee-totaler,i.e. I do not drink alcohol of ANY kind!
  #30  
Old 11-30-2003, 01:16 AM
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Challenger Chuck;
You have to understand that fiberglass likes to cause trouble and piss people off. So just ignore him if you want. Or tell him off and the mods will understand.
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