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NEW Ford 9 Inch Posi Traction Third Member

SAME DAY SHIPPING! Most orders ship within 24 hours.

Specs
Sold in Quantity:
Set
Spline Count:
-
Ring Gear Weight:
Standard
Differential Type:
Limited Slip
Spool Weight:
Standard
Housing Material:
Cast-Iron
Gear Ratio:
-
NEW Ford 9 Inch Posi Traction Third Member

Click image to enlarge

Details

Reviews (9)

Q & A (10)

What's in the Box

Info

Our completely NEW 9" Ford third members start with a heavy duty cast iron carrier featuring the larger, cast iron Daytona pinion support. Then we use a Richmond Powertrax Grip Pro differential in your choice of 28 or 31 spline.

All third members are assembled by our team of professionals and are delivered to you in a handy plastic carrying case, for an overall value that can’t be beat

Available in your choice of 3.50, 3.70, 3.89, 4.11 or 4.56 gear ratio ring & pinion. 

Customer Reviews

Rated 4.4 out of 5 by 9 reviewers.
RATING BREAKDOWN
9 reviews
5 Stars
6
4 Stars
2
3 Stars
0
2 Stars
1
1 Star
0
RECOMMEND THIS PRODUCT:

Jim
Verified Purchaser
Texas

It's always a pleasure doing business with speedway motors.

June 03, 2016
Build hot rods for a living, speedway motors is my go to source.
Yes, I recommend this product.
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Dave
Verified Purchaser
Verified Reviewer
Weatherford Tx

Best value in the business!!

March 01, 2016
Arrived super fast
Yes, I recommend this product.
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Texas Attitude Racing
Verified Purchaser
Bandera, TX

Perfect

August 21, 2015
This diff worked nicely. The posi made zero noise which is opposite of the locker style diffs that are used in the 9" arena. Definitely recommend on a street/Pro-Street vehicle. Happy and will purchase again for the next customer needing the similar situation.
Yes, I recommend this product.
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Quickie70
Verified Purchaser
Morrison, CO, USA

5 stars for service but wouldn't recomme

February 08, 2015
For the money, this unit can't be beat. On paper. It's got a stout housing, name brand parts, and it's 1/2 the price of a "big name" assembled third member, however it comes down to assembly, and mine was poorly assembled. I broke it in and ran red line heavy shockproof oil, but the ring and pinion ate each other within 1200 miles, and really started making noise about a hundred miles from anywhere, which was unsettling. However, speedway made it right after I returned it and was offered and new product or a refund, so speedway rocks. Again.
Pros:
  • customer service is top notch
  • Inexpensive
  • Quality parts
Cons:
  • poor setup
No, I would not recommend this product.
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JTstunts1
Verified Purchaser

killer!

October 20, 2014
I build everything myself but this time I needed to get the car together faster so I bought the diff assy already built, awesome for the price and saved me hours!
Pros:
  • quality product super clean
Cons:
  • didn't come with1350 yoke but easy fix
Yes, I recommend this product.
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jeeddii
Verified Purchaser

this item is good value

August 03, 2014
I have built many differentals.The patterns are well placed so I feel it will run quiet.I fell the pinion preload is to tight which I wil look at before I put it in the car
Pros:
  • Good Value
Cons:
  • pinnion preload too tight
Yes, I recommend this product.
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negative
Verified Purchaser

The product looked great.

June 04, 2014
The item shipped was the wrong item. I ordered a 28 axle spline, but I received a 31 axle spline third member. So I was unable to use it.
Yes, I recommend this product.
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Merchant Response:

Speedway Motors Customer Service team has issued this customer a refund for the incorrect item received. We apologize for any inconvenience this may have caused.
papabear
Verified Purchaser
Missouri

Quality built at a great price.

March 03, 2013
Nicely painted and even included a bottle of friction additive for the posi unit.
Pros:
  • neat storage case is included
Cons:
  • does not come with a gasket
Yes, I recommend this product.
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Charlie "Nuts and Bolts"
Verified Purchaser
Hartsdale, NY

No Gasket

June 22, 2012
Not installed yet, have't had time to get a gasket yet..
Pros:
  • Good product fast shippin
Yes, I recommend this product.
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Page 1 of 1

Product Q&A

10 questions : 10 answers

1 answers

just want to buy the red plastic container for the 3rd member just want to buy the red plastic container for the 8inch 3rd member

Hiro
California, USA
March 29, 2014

just want to buy the red plastic container for the 3rd member just want to buy the red plastic container for the 8inch 3rd member

Answers

March 31, 2014
EricM
Sorry I only offer the plastic case for 9" Ford which is part number 91081080.
1 answers

Ratio Sir/Ma'am, Looking to use this with your triangulated 4 bar kit for a 52 Chevy 3100, has a 383 engine with 700R4 trans. What ratio do I need for this third member? Wife will use this to drive 20mi each way to work 3 times a week and give her a little thrill from time to time at take off. Not sure if 3:70 or the 3:89 would fit the bill? Thank you in advance for the reply I appreciate your time as always.

50Two
December 15, 2013

Ratio Sir/Ma'am, Looking to use this with your triangulated 4 bar kit for a 52 Chevy 3100, has a 383 engine with 700R4 trans. What ratio do I need for this third member? Wife will use this to drive 20mi each way to work 3 times a week and give her a little thrill from time to time at take off. Not sure if 3:70 or the 3:89 would fit the bill? Thank you in advance for the reply I appreciate your time as always.

Answers

December 16, 2013
EricM
The rear end gear ratio is highly subjective to the drivers preference. Either of those gear ratios would work fine. The 3.70 ratio will provide slightly less RPM while cruising down the highway than 3.89 would. With the low first gear ratio of a 700R4 I would personally use a 3.50 or 3.70 gear ratio unless you are only concerned about performance. If using large rear tires (30" or taller) you may want to be in the 3.70 to 4.11 range however.
1 answers

Which housing is used on this assembly? Also, what brand of gears does this include? Wondering which housing this is, only says new in title and heavy duty in description. Need more info. Also who's gears are installed for this? I'm looking at getting a 3.70 ratio if that makes a diff.

madsow
Chanute, ks
October 05, 2013

Which housing is used on this assembly? Also, what brand of gears does this include? Wondering which housing this is, only says new in title and heavy duty in description. Need more info. Also who's gears are installed for this? I'm looking at getting a 3.70 ratio if that makes a diff.

Answers

October 07, 2013
Jason
The housing on the 9" posi traction third member is Speedway part #91048390 that is a new 36 pound heavy duty cast iron case with 3.062" forged steel caps, 5/8" HD grade 8 cap bolts and good for 1100 plus horsepower. The ring and pinion is from Richmond Gear.
1 answers

how do I tell if I have a short or long yoke? does it make a difference?

David
Virginia Beach, Virginia
January 05, 2012

how do I tell if I have a short or long yoke? does it make a difference?

Answers

January 10, 2012
John
Part number 91048445 Yoke used in this third member carries these specifications: * Thickness of ear where u-bolts go through is .818" or 13/16" * Depth from face to bottom of u-joint cap recess is .520 or 1/2" plus * Space between ears where u-joint caps fit is 3.211" or 3-3/16" plus * Overall length is 4" * Outside diameter at seal area is 1.813" * Center to center of u-bolt holes is 1-3/8" U-joint used is common 1 1/16 diameter cap with 3 7/32” spread.
1 answers

What U-Joint is this set up for?

Kelly
Stillwater, Oklahoma
April 17, 2015

What U-Joint is this set up for?

Answers

April 17, 2015
Eric
Expert
This third member requires a 1310 series U-joint such as 91045153 which is a 1 1/16" diameter cap and 3 7/32" wide.
1 answers

What is the hp limit on this? What posi is it? Eaton?

Devan
Ohio
June 17, 2015

What is the hp limit on this? What posi is it? Eaton?

Answers

June 17, 2015
Eric
Expert
This third member uses a Motive Gear differential part number 910109028 or 910109031. It is intended for street driven applications. If you are using this in a drag race scenario especially with a trans brake it is not well suited for that application. Sorry we do not have a horsepower rating on this third member. The use of the vehicle is more of a factor than the horsepower of the engine.
1 answers

Does this come with the 3.062 bearings or the 3.25 bearings?

Steve
Cologne, Mn.
October 31, 2015

Does this come with the 3.062 bearings or the 3.25 bearings?

Answers

November 02, 2015
Eric
Expert
These new case third members use a 3.062" carrier bearing OD.
1 answers

Will this work on a '74 f100 2wd was wondering if would bolt up correctly to my 9 inch rear.

Evan
Delaware
March 07, 2016

Will this work on a '74 f100 2wd was wondering if would bolt up correctly to my 9 inch rear.

Answers

March 09, 2016
Eric
Expert
Yes this will fit your 9" rear end but you will need to count your axle splines and order the correct one depending if you have 28 or 31 spline axles. You will likely need to install the yoke from yours onto the new third member unless they happen to be a matching size and length.
1 answers

will my moser 31 spline axles 1.325 fit?

PK
titusville,pa.
April 24, 2016

will my moser 31 spline axles 1.325 fit?

Answers

April 25, 2016
Eric
Expert
As long as your Moser axles are 31 spline for a 9" Ford then they will work with this third member.
1 answers

I am currently running a 4.56 Detroit locker, 28 spline 3rd member in my 71 Bronco. My wife refuses to drive it due to the Detroits characteristics on pavement in a lifted short wheel base vehicle (scares her). I know what's wrong with keeping her out from behind the steering wheel of MY Bronco right. Sorry, I digressed, is the Richmond Power Trax Grip Pro similar to a Detroit TruTrac torque sensing differential? No clutches? no additives?

Old Guy
Northern CA
June 07, 2016

I am currently running a 4.56 Detroit locker, 28 spline 3rd member in my 71 Bronco. My wife refuses to drive it due to the Detroits characteristics on pavement in a lifted short wheel base vehicle (scares her). I know what's wrong with keeping her out from behind the steering wheel of MY Bronco right. Sorry, I digressed, is the Richmond Power Trax Grip Pro similar to a Detroit TruTrac torque sensing differential? No clutches? no additives?

Answers

June 08, 2016
John
Expert
The Powertrax Grip differentials are progressive and variable traction sensitive similar to the Tru Trac versions and are a big benefit over the full lockers like the one by Powertrax. Plus you don't have the annoying noise during daily driving and eliminate the additives required.
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