• Mustang Forums
  • 1996 - 2004 SN95 Mustang -General/Talk-
  • SVT Tech Forum

99 pumpkin with 4.10 gears too tight?

  • Thread starter Thread starter AvalancheSVT
  • Start date Start date Oct 4, 2018

AvalancheSVT

10 Year Member
Jun 12, 2005
573
37
49
Oct 4, 2018
#1
  • Oct 4, 2018
  • #1
Hey guys, so I've got this whole rear axle setup from a 99 cobra in really god condition for its age.
However, when I turn the pinion flange its pretty difficult to turn with my hand. Like, impossible if its slick.

The fluid that came out of it was black as night and it has 4.10 gears and it came out of a road race car.

Do you guys think it could be improperly shimmed or the pinion preload could be too right or something? I have the cover off and it sitting on my bench right now, I'm gonna try adding some fresh oil to the bearings tonight to see if that helps it out a bit but I would think it should spin without any real effort.

What do you guys think? I'm doing all new bushings and new clutches but I'm wondering if I should do a full rebuild.
 

Attachments

  • pumpkinguts.webp
    282.1 KB · Views: 339

Hoytster

I don't dare do that to my Knob
20+ Year Stangneter
Dec 30, 2002
1,069
700
164
Cornwall, PA
Oct 4, 2018
#2
  • Oct 4, 2018
  • #2
They usually have some resistance, but you should be able to turn it fairly easily by hand with nothing connected to it. I have an 03' unit in my garage with a fresh rebuilt 4.10 setup I can check in an hour or so and let you know what my pre-load is.
 

Hoytster

I don't dare do that to my Knob
20+ Year Stangneter
Dec 30, 2002
1,069
700
164
Cornwall, PA
Oct 4, 2018
#3
  • Oct 4, 2018
  • #3
So my pinion preload on this fresh rebuild is around 18 in/lbs, which appears to be in spec. I'm showing a used pinion preload should be 8-14 in/lbs. So yes, you should be able to spin it by hand fairly easily. Personally, I would rebuild it anyways if you have it out.
 

AvalancheSVT

10 Year Member
Jun 12, 2005
573
37
49
Oct 4, 2018
#4
  • Oct 4, 2018
  • #4
I suspect it may just be shimmed improperly. I'm going to pull the diff and see what the pinion gear feels like by itself. I really don't want to have to mess with pinion preload if I don't have to. thanks!
 
Reactions: Hoytster

AvalancheSVT

10 Year Member
Jun 12, 2005
573
37
49
Oct 5, 2018
#5
  • Oct 5, 2018
  • #5
The pinion preload or outside bearing was the problem. OVER 25 INCH LBS of resistance to make it turn. way passed spec.

looks like she's gonna get a full rebuild. one of the carrier bearings fell apart when I took it out. This little unit was definitely beat to hell lol

gears are 4.10 and have ford stamps, so that's awesome
 
Reactions: Hoytster

Hoytster

I don't dare do that to my Knob
20+ Year Stangneter
Dec 30, 2002
1,069
700
164
Cornwall, PA
Oct 6, 2018
#6
  • Oct 6, 2018
  • #6
Wow, no wonder you had a hard time turning it by hand! That's good your rebuilding it, those things usually get beat up on road race cars without a cooling system.
 

AvalancheSVT

10 Year Member
Jun 12, 2005
573
37
49
Oct 16, 2018
#7
  • Oct 16, 2018
  • #7
So, the gears that came out of this thing don't have pinion depth markings on the face which might explain why it was set up improperly.
My instinct is to buy a new set of ford racing gears from AM and just make sure I have all the right stuff going forward.

What do you guys think? its 175 bucks for knowing I have the right gears and it means I don't have to guess at pinion depth.
 
You must log in or register to reply here.

Similar threads

J
2004 Mustang 3.8L V6 vibrations above 65 MPH and differential leaks
  • joeybuddy96
  • Mar 16, 2026
  • SN95 V6 Mustang Tech
Replies
16
Views
585
SN95 V6 Mustang Tech Jul 14, 2026
joeybuddy96
J
3
Eight inches is enough for me...
  • 351MooseStang
  • Nov 27, 2025
  • 1974 - 1978 Mustang II Talk & Tech
Replies
5
Views
577
1974 - 1978 Mustang II Talk & Tech Mar 2, 2026
Bullitt347
O
Progress Thread LTD-ing
  • OX1
  • Mar 15, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
8
Views
379
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Apr 6, 2026
OX1
O
S
Drivetrain Downshifting from 3rd to 2nd issue
  • Scott_S
  • Apr 23, 2026
  • Fox 5.0 Mustang Tech
  • 2
Replies
24
Views
762
Fox 5.0 Mustang Tech Jun 14, 2026
Mindseye007
D
66 Coupe Progress Thread
  • DTCRAWLEY
  • Apr 19, 2026
  • 1965 - 1973 Classic Mustangs -General/Talk-
  • 2 3
Replies
43
Views
1K
1965 - 1973 Classic Mustangs -General/Talk- Jun 17, 2026
DTCRAWLEY
D
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1996 - 2004 SN95 Mustang -General/Talk-
  • SVT Tech Forum
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?