Moparchat - Home of MOPAR enthusiasts worldwide!



Go Back   Moparchat - Home of MOPAR enthusiasts worldwide! > Technical Forums > Performance Talk

Click here to search for Mopar cars and parts for sale.


Reply
 
Thread Tools Display Modes
  #1  
Old 10-21-2007, 01:02 PM
dartster73 dartster73 is offline
Inactive User
 
Join Date: Aug 2006
Location: SoCal
Posts: 30
Default 8 1/4 rear end traction questons

I know I should pony up and get a 8 3/4 but for the sake of argument and saving a few hundred bucks I'm curious if anyone has had much experience switching an open carrier 8 1/4 to a posi. Its a 73 Dart Sport that was originaly a slant six with 904 and is now a 360/727. I'm not exactly sure of the ratio but at 75 mph I'm turning 2,800rpm on 245/60 15" tires. So I'm guessing 3:25's. I've found the Auburn and the Mopar units pretty reasonable and wondered if anyone had any input of which is better. I've played with Ford 9" and Chevy 10 bolts but this is my first adventure into the world of Mopar rear ends.
Right now at anything under 20mph if I stab the gas it annihilates the right side tire.
Reply With Quote
  #2  
Old 10-21-2007, 02:00 PM
1976 Aspen's Avatar
1976 Aspen 1976 Aspen is offline
Inactive User
 
Join Date: Feb 2004
Location: Roseau, MN
Posts: 86
Default

Unless you're running big power the 8-1/4 will do just fine. I have a 1976 Aspen that I bracket race and it lays down 1.51 60ft times and runs 10.75 consistantly with an 8-1/4 rearend. The reaerend has over 400 passes on it and is still in good shape. I have a sure grip with 4.10 richmond gears. In my opinion the Sure Grip in the 8-1/4 is stronger than the 8-3/4 but some people don't. I wouldn't worry about the strength if you're not going any faster than I am. Add a pinion snubber and some drag radials and you'll have alot of traction. I just switched to CalTracs and their monoleaf springs and Rancho 9000 shocks and I love it. I run a 9" M/T slick so traction is excellent. Good Luck!!!
Reply With Quote
  #3  
Old 10-21-2007, 08:57 PM
dodger1 dodger1 is offline
Inactive User
 
Join Date: Feb 2004
Location: Princeton BC
Age: 85
Posts: 2,648
Default

I have an Auburn in my 8 1/4 (360/904 Mirada) Had the rear freshened and a new unit installed in 02 when I swapped out the 7 1/4. Absolutely no issues since, but I'm not racing it either.
Reply With Quote
  #4  
Old 10-21-2007, 11:53 PM
MOPEkid's Avatar
MOPEkid MOPEkid is offline
Inactive User
 
Join Date: Sep 2007
Location: Monument, CO
Posts: 470
Default

I eventually want to put an 8-1/4 rear in my Duster too. Do all 8-1/4's have large bolt patterns? Can the gears be easily swapped out, kinda like an 8-3/4 rear?
Reply With Quote
  #5  
Old 10-22-2007, 12:02 AM
1976 Aspen's Avatar
1976 Aspen 1976 Aspen is offline
Inactive User
 
Join Date: Feb 2004
Location: Roseau, MN
Posts: 86
Default

MOPEkid, I have an extra 8-1/4 for sale right now if you're interested. It's out of a 1976 Dodge Aspen. It's got a Sure Grip, pinion snubber, 4.10 Richmond Gears, and Moser axles. I'll sell it very reasonable. If you're interested, call me at 218-689-2586 Ryan
Reply With Quote
  #6  
Old 10-22-2007, 09:02 PM
dodger1 dodger1 is offline
Inactive User
 
Join Date: Feb 2004
Location: Princeton BC
Age: 85
Posts: 2,648
Default

Correct me if I'm wrong, but weren't later (mid-70's and later 8 1/4, 9 1/4 ) Mopar Suregrips a cone-type lsd - aka Auburn? as opposed to clutch-type as in PosiTraction used in the 8 3/4 and Dana rears?
Reply With Quote
  #7  
Old 10-23-2007, 10:06 AM
rumblefish360's Avatar
rumblefish360 rumblefish360 is offline
Moparchat Bronze member
 
Join Date: May 2000
Location: C
Age: 57
Posts: 11,120
Default

dartster73, the rears set up easy. You should not have a problem in doiong one yourself or having it done. Mopar, auburn, etc... make posis for it. Gears can be had in all sorts of ratios.


Quote:
MOPEkid I eventually want to put an 8-1/4 rear in my Duster too. Do all 8-1/4's have large bolt patterns? Can the gears be easily swapped out, kinda like an 8-3/4 rear?
1. No
2. No
Reply With Quote
  #8  
Old 10-23-2007, 06:12 PM
MOPEkid's Avatar
MOPEkid MOPEkid is offline
Inactive User
 
Join Date: Sep 2007
Location: Monument, CO
Posts: 470
Default

I guess more specifically, do 8-1/4" rears exist for '70 A-bodies with large bolt patterns? And how common are they if they do exist?
Reply With Quote
  #9  
Old 10-23-2007, 10:16 PM
rumblefish360's Avatar
rumblefish360 rumblefish360 is offline
Moparchat Bronze member
 
Join Date: May 2000
Location: C
Age: 57
Posts: 11,120
Default

Yes, the larger bolt patterns are found in the later years. I forget what year they started in though.
Fairly common.
I picked mine up for $200 with a 3.21 suregrip inside. Add 5.9 for a rattle can of black paint, presto.
Attached Images
File Type: jpg 100_0826.JPG (58.7 KB, 18 views)
Reply With Quote
  #10  
Old 10-24-2007, 06:58 AM
Dart14 Dart14 is offline
Inactive User
 
Join Date: Jan 2005
Location: Lincoln University, PA
Posts: 114
Default

A body large bolt pattern began 73 model year
Reply With Quote
  #11  
Old 10-24-2007, 11:27 AM
MOPEkid's Avatar
MOPEkid MOPEkid is offline
Inactive User
 
Join Date: Sep 2007
Location: Monument, CO
Posts: 470
Default

So I wouldn't have any problems putting one in my '70 Duster? $200 is pretty good, I thought they were going to be $400+.
Reply With Quote
  #12  
Old 10-25-2007, 10:03 AM
rumblefish360's Avatar
rumblefish360 rumblefish360 is offline
Moparchat Bronze member
 
Join Date: May 2000
Location: C
Age: 57
Posts: 11,120
Default

Thanks Dart14.

It was $200 without backing plates for the brakes. This is something I didn't mind since I had and intended to use (And did) a set of 11 inch drums.
Reply With Quote
  #13  
Old 10-25-2007, 02:16 PM
dwc43's Avatar
dwc43 dwc43 is offline
Banned
 
Join Date: Sep 2002
Location: Shelbyville,Tn.
Age: 54
Posts: 23,987
Biggrin

Quote:
Originally Posted by MOPEkid View Post
So I wouldn't have any problems putting one in my '70 Duster? $200 is pretty good, I thought they were going to be $400+.
You can get a direct bolt in. And I can pick one up here locally for $100 ready to install. Just did one last spring in a Volare'. Took it from a Wagon at the junkyard for $100. : up:
Reply With Quote
  #14  
Old 10-25-2007, 02:19 PM
dwc43's Avatar
dwc43 dwc43 is offline
Banned
 
Join Date: Sep 2002
Location: Shelbyville,Tn.
Age: 54
Posts: 23,987
Biggrin

Quote:
Originally Posted by 1976 Aspen View Post
In my opinion the Sure Grip in the 8-1/4 is stronger than the 8-3/4 but some people don't!!
That's not just opinion there. You'll find it in the Mopar Chassis books that the 1/4 was desinged as a replacment for the 3/4. It's actually stronger and cheaper to produce. It does not have the flex that the open banjo housing of the 3/4 has. Therefore it does not easily brake axles and bearing caps and such.
Reply With Quote
  #15  
Old 10-26-2007, 01:06 AM
dave571's Avatar
dave571 dave571 is offline
Inactive User
 
Join Date: Feb 2001
Location: carstairs,alberta,canada
Posts: 2,809
Default

I've heard that before.

Can you scan in the page that says the 8 1/4 is stronger than the 8 3/4?
Then you could post it here for us to see.
I for one would like to see that info, and have never read anything like that before.

Thanks
Reply With Quote
  #16  
Old 10-26-2007, 02:13 AM
bjoehandley bjoehandley is offline
Inactive User
 
Join Date: Jun 2003
Location: WeGo, Chi-town, Il
Age: 47
Posts: 3,449
Default

What do the 8 1/4" you guys are talking about relate to the 8.25" rears in trucks like the Dakota and Cherokee?
Reply With Quote
  #17  
Old 10-26-2007, 09:44 AM
rumblefish360's Avatar
rumblefish360 rumblefish360 is offline
Moparchat Bronze member
 
Join Date: May 2000
Location: C
Age: 57
Posts: 11,120
Default

What do you mean Joe?
There basicly the same rear. Room was made for the anti-lock ring. Axle spline count changed.
Reply With Quote
  #18  
Old 10-26-2007, 07:22 PM
dodger1 dodger1 is offline
Inactive User
 
Join Date: Feb 2004
Location: Princeton BC
Age: 85
Posts: 2,648
Default

I've been told (think it was a Mopar Action item) the Dak axle is a beefed-up 8 1/4 with slightly larger (8 3/8) ring and better axles. dwc, you sure you're not referring to the 9 1/4, which I had heard was the stronger replacement for the 3/4.
Reply With Quote
  #19  
Old 10-26-2007, 08:14 PM
rumblefish360's Avatar
rumblefish360 rumblefish360 is offline
Moparchat Bronze member
 
Join Date: May 2000
Location: C
Age: 57
Posts: 11,120
Default

DW has been screaming what he wrote for years and is the only one doing so.

Both rears, 8-1/4 or 9-1/4 are C clip rears that came about the same time.
The C clip seems to be a problem for many people. I have one of each with over 300,000 miles on it (Each) and it see everyday driving just fine.
I'm not a light footed driver by any means.
Reply With Quote
  #20  
Old 10-26-2007, 10:31 PM
dodger1 dodger1 is offline
Inactive User
 
Join Date: Feb 2004
Location: Princeton BC
Age: 85
Posts: 2,648
Default

C-clip eliminating mods have been a good seller to GM folks, but I've never heard of a Chrysler C-clip design giving problems. More to the point, I've never seen a "C-clip eliminator" advertised for a Mopar.. I have re and re'd axles on my 8 1/4 as well as on our 89 S-15 Jimmy and I didn't see a lot of difference in the design principles, so I assume it's engineering excellence in our favor, again! BTW, I paid around $400 for an overhaul plus a new Auburn unit several years ago, so rumble's deal is definitely a DEAL!!
Reply With Quote
  #21  
Old 10-26-2007, 11:40 PM
bjoehandley bjoehandley is offline
Inactive User
 
Join Date: Jun 2003
Location: WeGo, Chi-town, Il
Age: 47
Posts: 3,449
Default

Quote:
Originally Posted by rumblefish360 View Post
What do you mean Joe?
There basicly the same rear. Room was made for the anti-lock ring. Axle spline count changed.
Actually, that's exactly what I was wondering

I've read different things about this axle, some people thing they're as weak as the Dana 35 hwile others claim they're as strong as the Dana 44 in the Cherokee applications, especally if you get the later 29 spline axle (IIRC mine and Swinger's should have that ) What limited slip units are there for this axle? Most of what I see for my application is either for D35 or D44
Reply With Quote
  #22  
Old 10-27-2007, 12:13 AM
littlecampbell littlecampbell is offline
Banned
 
Join Date: Mar 2002
Location: canuck land
Age: 73
Posts: 750
Default

Quote:
Originally Posted by dave571 View Post
I've heard that before.

Can you scan in the page that says the 8 1/4 is stronger than the 8 3/4?
Then you could post it here for us to see.
I for one would like to see that info, and have never read anything like that before.

Thanks
When have you ever seen dingleberry post a scan or diddly squat to back up anything Dave?....Hope you are doing well Dave....old age has taken the toll. Dart is going on the block in the spring......heres a fun shot of the "moonbat".... some things never change...
Attached Images
File Type: jpg galzdsfivj_6580698.jpg (13.8 KB, 19 views)
Reply With Quote
  #23  
Old 10-27-2007, 08:32 PM
rumblefish360's Avatar
rumblefish360 rumblefish360 is offline
Moparchat Bronze member
 
Join Date: May 2000
Location: C
Age: 57
Posts: 11,120
Default

MoPar sells a suregrip unit for the 8-1/4 axle.
So does the other companys out there. Ummmm, errrrr, drawing a blank, thiiiiiiiiiiiiiink..... crap! fire alarm just went off..... smake from the dome set it off.

All's good.

Auburn! HA! ummmm , brain fart.......
Reply With Quote
  #24  
Old 10-28-2007, 09:17 PM
usdart's Avatar
usdart usdart is offline
Inactive User
 
Join Date: Jun 2002
Location: West Richland Washington
Age: 72
Posts: 644
Default 8 1/4 Diffs

Just a quick heads up from someone who's been there...

The Aspen / Volare rear ends are not a direct bolt in on a Dart.

The shock pltes are different as is the shackle attachment.

I used the Springs and shackles off my 7 1/4 and cut and welded the shock plates in the right position.
Reply With Quote
  #25  
Old 10-29-2007, 12:57 AM
dave571's Avatar
dave571 dave571 is offline
Inactive User
 
Join Date: Feb 2001
Location: carstairs,alberta,canada
Posts: 2,809
Default

Quote:
Originally Posted by littlecampbell View Post
some things never change...
For sure.
Good to see you on the board man. Missed you at the olde time race the last couple years.

In all seriousness, if an article that states the 8 1/4 is stronger than the 8 3/4 really exists, I would love to see it.

I've seen the attached pic before, and have no problem with Dwc peronally.


I'm not anti 8 1/4. I've abused a few and broken one. I would not hesitate to use one, if I had a car with one in it, BUT I'd just like to see this claim backed up if at all possible.
Reply With Quote
  #26  
Old 10-29-2007, 09:03 AM
Sterling Sterling is offline
Inactive User
 
Join Date: Feb 2000
Location: Pottstown,Pa.U.S.A.
Posts: 36
Default

The problem you might have in installing a sure grip in your differential is adjusting the carrier bearing preload and backlash. You need a special tool to go in thru the axle tube to turn the spanner. I made one for myself. Also if you are going to race it, and go quicker than 11.00 et at a NHRA track, you will need aftermarket axles and a c-clip eliminator kit.
Reply With Quote
  #27  
Old 10-29-2007, 05:22 PM
JVMopar's Avatar
JVMopar JVMopar is offline
Senior Member
 
Join Date: Feb 2000
Location: Mellen, WI
Age: 42
Posts: 2,524
Default

I have a 8 1/4 in my dakota. 220,000 miles on it and I beat the hell out of the truck. I did put a trac lock in it at 170,000 It could lock harder but it works. Randy's ring and pinion sells the tool to adjust the spanners I think it was $35 if I remember correctly.
Reply With Quote
  #28  
Old 10-31-2007, 10:50 PM
dave571's Avatar
dave571 dave571 is offline
Inactive User
 
Join Date: Feb 2001
Location: carstairs,alberta,canada
Posts: 2,809
Default

Quote:
Originally Posted by dave571 View Post
In all seriousness, if an article that states the 8 1/4 is stronger than the 8 3/4 really exists, I would love to see it.

.
Still waiting.......
Reply With Quote
  #29  
Old 11-01-2007, 04:10 PM
dodger1 dodger1 is offline
Inactive User
 
Join Date: Feb 2004
Location: Princeton BC
Age: 85
Posts: 2,648
Default

Quote:
dwc, you sure you're not referring to the 9 1/4, which I had heard was the stronger replacement for the 3/4.
dwc, hello???
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
traction sfr Circle Track Chat 2 08-23-2011 06:07 PM
Lots of questons. josephtpeterson Performance Talk 12 09-03-2009 08:34 AM
Best street tires for rear end traction? SCMike Performance Talk 12 08-20-2007 11:14 PM
Has anyone added rear traction bars to their 4x4 Dodge guy Ram Truck Chat 2 05-14-2003 10:03 PM
Traction help furypete Performance Talk 13 06-01-2002 01:23 AM




All times are GMT -4. The time now is 10:03 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
. . . . .