• Mustang Forums
  • 1965 - 1973 Classic Mustangs -General/Talk-
  • Classic Mustang Specific Tech

Rear End Dilemma

  • Thread starter Thread starter The Dan
  • Start date Start date Nov 8, 2004

Which Rear End?

  • 8" Outfitted as described below

    Votes: 5 25.0%
  • 9" Outfitted as described below

    Votes: 15 75.0%

  • Total voters
    20
  • Poll closed Nov 13, 2004.
  • 1
  • 2
Next
1 of 2 Next Last
T

The Dan

New Member
Jul 16, 2003
319
0
0
Orange County, CA
Nov 8, 2004
#1
  • Nov 8, 2004
  • #1
I keep going back and forth between the 8" and 9". If I go 8" it would be:
8" with 67 center section, Auburn Pro Limited Slip, 3:55 gears. If I go 9" it would be 9" with Auburn Pro Limited Slip, 3:55 gears. I'm around 300-325hp, but waiver as to what I want to do because of the different opinions of what each is capable of. I just don't want to regret anything either way. Help a man out!
 

reenmachine

20+ Year Stangneter
Jun 27, 2004
1,258
2
38
Montrose, CA
Nov 8, 2004
#2
  • Nov 8, 2004
  • #2
I don't think you necessarily need to go to the expense of a 9" upgrade with 300-325 HP.
 

Pbum5

Member
Oct 27, 2004
515
0
17
Minneapolis, MN
Nov 8, 2004
#3
  • Nov 8, 2004
  • #3
If you have no rearend Go with a 9". It's not that much more and will take a lot more abuse if you keep adding power.
 

Max Power

Active Member
Jul 31, 2003
1,774
1
36
St Paul
Nov 8, 2004
#4
  • Nov 8, 2004
  • #4
I am not voting till you post some dollar numbers!
 

ratio411

Founding Member
Apr 21, 2002
3,870
73
109
Pensacola FL
Nov 8, 2004
#5
  • Nov 8, 2004
  • #5
Don't waste your money on an 8"...
Let's just assume that your stated power level would not hurt an 8" rear... (it would IMO)
What happens when the mod bug bites you again? You know it will... bolt on a few more HP here and there, next thing you know, the 8" is out classed and chewed up by your engine.
Just do the 9" and have strength to grow when you want more power.
Dave
 
T

The Dan

New Member
Jul 16, 2003
319
0
0
Orange County, CA
Nov 8, 2004
#6
  • Nov 8, 2004
  • #6
Max,

To build my current 8" as described $1200

I haven't looked into the 9" yet, but I figure around $1500???

Those that have recently built a 9" care to chime in. And if you got all the parts at cost becasue your Uncles Brother in-law's nephew knows a guy at the parts store, that doesn't count!
 

67GTFastback

Founding Member
Dec 14, 2001
1,210
0
0
Calgary, Alberta
Nov 8, 2004
#7
  • Nov 8, 2004
  • #7
The Dan said:
Max,

To build my current 8" as described $1200

I haven't looked into the 9" yet, but I figure around $1500???

Those that have recently built a 9" care to chime in. And if you got all the parts at cost becasue your Uncles Brother in-law's nephew knows a guy at the parts store, that doesn't count!
Click to expand...

I too agree with Ratio, you might as well buy one that will support future mods/upgrades, therefore I would go with the 9". Good luck and let us know which one you choose.
 
M

mustangbrad

Member
Aug 16, 2004
127
5
19
Nov 9, 2004
#8
  • Nov 9, 2004
  • #8
If you are done with the engine now the 8" will be fine. If you have any future plans to add power down the road, I would bite-the-bullet and go 9" now.
 

Max Power

Active Member
Jul 31, 2003
1,774
1
36
St Paul
Nov 9, 2004
#9
  • Nov 9, 2004
  • #9
If they are that close in price, go 9 inch all the way. The only way I would recommend the 8 inch is if you were saving a lot of money and had no further plans for mods.
 

stangman67

Member
Feb 8, 2003
294
0
17
connecticut
Nov 9, 2004
#10
  • Nov 9, 2004
  • #10
The Dan said:
Max,

To build my current 8" as described $1200

I haven't looked into the 9" yet, but I figure around $1500???

Those that have recently built a 9" care to chime in. And if you got all the parts at cost becasue your Uncles Brother in-law's nephew knows a guy at the parts store, that doesn't count!
Click to expand...

Where did you get a price of $1200 for a center section? Seems awfully high.
 
J

jaredgoodwin

New Member
Sep 29, 2004
62
0
0
Nov 9, 2004
#11
  • Nov 9, 2004
  • #11
9"

I recently faced the same dilemna, went with the 9", no regrets. I picked up ring and pinion gears from summit for $70 less for a 9" than they have 8" gears. Check them out. Helps to offset the additional cost. I don't think you want the rear end to be the weakest link in your drivetrain......
 
T

The Dan

New Member
Jul 16, 2003
319
0
0
Orange County, CA
Nov 9, 2004
#12
  • Nov 9, 2004
  • #12
$1,200 was for an Auburn Pro, Gears, Seals, Bearings, 67 Center Section, and Labor.
 

ratio411

Founding Member
Apr 21, 2002
3,870
73
109
Pensacola FL
Nov 9, 2004
#13
  • Nov 9, 2004
  • #13
That is a serious consideration...
8" stuff is expensive and fairly hard to come by due to it's relative unpopularity.
The 9" is the gold standard for all of the performance world and you can get competitively priced parts on any street corner (j/k).
The thing is, the core for an 8" to build is cheap, but then the build is as much or more than the 9".
You pay a little more for the 9" core, but the parts are everywhere, strong, and reasonable due to it's popularity.
Heck, the Nascar guys have used ONLY 9" rears in their cars for decades... no matter GM, Ford, Mopar... that is why gear sets are cheap and available in almost any ratio you can imagine.
When I lived in Charlotte, 9" parts were found everywhere. Good stuff, cheap, run 1 race because the Nascar guys never used a part twice.
Dave
 

SadbutTrue

Founding Member
May 1, 2002
2,390
4
49
Granada Hills, California
Nov 9, 2004
#14
  • Nov 9, 2004
  • #14
ratio... curious... do you know if Toyota will use the 9" in its Nascar vehicles. That would say something...

But yeah, I would just go with the 9" now. Believe it or not, I think ti will probably end up being cheaper, and be stronger. I was able to convert to a 9 inch rear (reusing my 28 spline axles for the time being) for about $650 total, with a rebuilt 9" third member off ebay and having a shop cut up a housing. You could do the same thing, except with a 31 spline third member and new 31 spline axles for under a grand for sure.
 

ratio411

Founding Member
Apr 21, 2002
3,870
73
109
Pensacola FL
Nov 9, 2004
#15
  • Nov 9, 2004
  • #15
I don't know about Toyota...
I haven't kept up with Nascar since I left Charlotte.
I just thought it was neat while I was there, that you could be like a scavenger picking up Nascar parts for cheap. When one cutting edge head was dropped in favor of another, they would just dump the used heads on the market. If you knew where to go, you could get exotic stuff cheap. Same went for the rear end parts and Jericho toploaders.

Fwiw, I am going to cut the 'pumpkin' out of my 8" and drop in a 9" that I have laying around, then reuse my 8" axles, bearings, and tubes with a 28 spline diff.
They say that you should never narrow or mod a rear end housing from the 'inside', but instead from the flange ends, for strength reasons... so I will weld a back brace on mine when done.
The 28 spline 9" stuff and standard carrier, while not super stout, will handle ALOT more abuse than even a built 8".
Dave
 

stangman67

Member
Feb 8, 2003
294
0
17
connecticut
Nov 9, 2004
#16
  • Nov 9, 2004
  • #16
I thought the axles were the weakest link in the 8"? Seems that the 9" rear setup would be as weak with these axles.
 

67bluestang

New Member
May 13, 2003
193
0
0
Tucson, Arizona
Nov 9, 2004
#17
  • Nov 9, 2004
  • #17
Ratio411 quote: "so I will weld a back brace on mine when done"

I wouldn't weld the the back brace on when done. The back brace should be welded on, then the housing ends should be welded on, but only when using a bar through the housing to maintain straightness of the housing. A back brace really isn't necessary unless you have a high horsepower car and using a transbrake and big slicks. I shouldv'e put one on my Trans Am when i narrowed it, but i never had any problems in 12 years. I left at 5800 rpm against the transbrake, 33X16 slicks, best of 9.00 @ 149.94.

ps: i'd say Toyotas will have a 9".
 
M

Mosse

Founding Member
Oct 22, 2002
229
0
0
Finland, Tampere
Nov 10, 2004
#18
  • Nov 10, 2004
  • #18
There was some talk about Curries new 8" pumpkins. Does anybody know about them?

They also have it on aluminum on their web page. 9" rear weights A LOT more than 8", which is an issue if you don´t run only on dead flat roads. At least here north the roads are terrible sometimes...
 

Edbert

Founding Member
Jul 13, 2002
3,548
32
109
Austin TX
Nov 10, 2004
#19
  • Nov 10, 2004
  • #19
If you are goiung to stay under 375-400 RWT for the forseeable future then stick with the 8. They are more efficient at transferring power and weigh a LOT less. You can hit the 400+ mark if you get it tricked out, but that will likely cost as much or more than a normal 9 that can take more abuse.
 

jbsteven

New Member
Sep 4, 2004
156
0
0
Nov 10, 2004
#20
  • Nov 10, 2004
  • #20
I am in the market to buy a 9 inch full setup today and need some pointers on where to purchase. I need the rear end, gear and third member.

any ideas on websites where I can find these?

thanks
 
  • 1
  • 2
Next
1 of 2 Next Last
You must log in or register to reply here.

Similar threads

3
Eight inches is enough for me...
  • 351MooseStang
  • Nov 27, 2025
  • 1974 - 1978 Mustang II Talk & Tech
Replies
5
Views
545
1974 - 1978 Mustang II Talk & Tech Mar 2, 2026
Bullitt347
R
What's it Worth? 1997 Cobra, a ton of mods and restoration
  • riored97snake
  • Jun 18, 2026
  • What is it Worth?!?!?
Replies
2
Views
113
What is it Worth?!?!? Jun 21, 2026
riored97snake
R
C
Suggestions for rear diff gears - 1969 Mach 351W 4v
  • cfauvel
  • Apr 8, 2024
  • Classic Mustang Specific Tech
Replies
10
Views
2K
Classic Mustang Specific Tech Jun 27, 2024
cfauvel
C
Tightening upper control arm bushings at ride height dilemma… need some help
  • AnthonyA1234
  • Dec 27, 2024
  • Fox 5.0 Mustang Tech
  • 2 3
Replies
51
Views
5K
Fox 5.0 Mustang Tech Feb 27, 2025
General karthief
R
8.8 rear end for '67 coupe, shortened - next steps
  • rubendenver
  • Dec 15, 2024
  • 1965 - 1973 Classic Mustangs -General/Talk-
Replies
2
Views
725
1965 - 1973 Classic Mustangs -General/Talk- Jan 8, 2025
GOvert
G
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1965 - 1973 Classic Mustangs -General/Talk-
  • Classic Mustang Specific Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?