• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech

Pinion shims/depth on 8.8 gear install.. advice..

  • Thread starter Thread starter wifenatesit
  • Start date Start date Dec 15, 2006
W

wifenatesit

New Member
Oct 20, 2006
2
0
0
Dec 15, 2006
#1
  • Dec 15, 2006
  • #1
hey all.. i'm in the middle of a gear swap on my 8.8 axle.. heres my dilemma:
I'm pulling out a set of 4.10's which worked fine, no gear noise for many 10second runs in my 86 stang. The gears are still perfect. I am installing 4.88 ford motorsport gears to better match up with the rpm needs of my new engine.

I figured i could just measure the overall thickness of my old pinion with the shim that was in it (total pinion thickness/depth), and then just measure up the new one I was installing, and add the correct shim to get the same pinion/depth/thickness as the old pinion.. all seems well, but I just want to verify two things:

1) The old gears are not ford motorsport gears. they are aftermarket. The new gears are ford motorsport gears. ford "supposedly" sets their gears up to work with a standard .030 shim, and sometimes they are machined +2,-3, but not much off that.
2) The new ring gear is somewhat thicker than the old ring gear... is this just because of the larger number of teeth due to the 4.88s vs. 4.10s or is this added thickness going to destroy my theory/method of installing my new gears using the old pinion's total thickness/depth? or perhaps the added thickness/teeth angle is just going to affect my backlash shim settings and not bother my pinion depth?

The new ford motor gears required about .0175 of shim (as opposed to the quote "standard .030" that someone told me ford gears all utilize...) to equal(match) the old pinion thickness/depth of 1.908. I know i can just install the whole thing and read the teeth with marking compound,but its just a real pain to put it all together and then pull it all apart again, pull the bearing off, and put in a different shim. and no, i don't have access to a pinion depth gauge.. so i gotta do this the old fashioned way.

so bottom line is.. for a baseline.. match my old pinion depth which worked fine, or throw it all to the wind and put a .030 shim in there?

thanks!
 
J

javier302

New Member
Nov 8, 2006
48
0
0
Dec 15, 2006
#2
  • Dec 15, 2006
  • #2
check your pm
 
W

wifenatesit

New Member
Oct 20, 2006
2
0
0
Dec 15, 2006
#3
  • Dec 15, 2006
  • #3
also. .can anyone identify two things that are written on the bottom of my pinion gear... one is "135".. the other one is "2.538"

thanks!
 

MikeC

Founding Member
Aug 1, 2002
240
0
16
SLC, UT
Dec 15, 2006
#4
  • Dec 15, 2006
  • #4
I just went from the stock 2.73 to FMS 3.73 gears. Stock had a 0.025" pinion shim. After some trial and error I ended up with a 0.030" shim and after setting the backlash to 0.009", I have a near perfect pattern with the compound. I haven't driven it yet so I don't know ihow it'sgoing to sound. The side shims will also change the pattern, not just the backlash.
These two links helped me a lot.

http://www.corral.net/tech/drivetrain/gears.html

http://www.explorerforum.com/forums/showthread.php?t=144780

I think one of them explaines the markings on the pinion gear.
 
You must log in or register to reply here.

Similar threads

K
Drivetrain '87 5.0 Installing New Ring Gear and Pinion - Pattern Questions
  • karhoot
  • Apr 23, 2026
  • Fox 5.0 Mustang Tech
Replies
10
Views
382
Fox 5.0 Mustang Tech May 9, 2026
Mindseye007
Engine Starter ring gear depth. 3/8 or 3/4 inch?
  • 92Rustang
  • Aug 4, 2025
  • Fox 5.0 Mustang Tech
Replies
4
Views
337
Fox 5.0 Mustang Tech Aug 22, 2025
Rcdgl
R
3
Eight inches is enough for me...
  • 351MooseStang
  • Nov 27, 2025
  • 1974 - 1978 Mustang II Talk & Tech
Replies
5
Views
576
1974 - 1978 Mustang II Talk & Tech Mar 2, 2026
Bullitt347
O
8.8 Pinion Nut Leak
  • OX1
  • Jan 3, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
15
Views
793
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Jan 5, 2026
OX1
O
J
2004 Mustang 3.8L V6 vibrations above 65 MPH and differential leaks
  • joeybuddy96
  • Mar 16, 2026
  • SN95 V6 Mustang Tech
Replies
16
Views
576
SN95 V6 Mustang Tech Jul 14, 2026
joeybuddy96
J
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang 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?