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

Popping / Grinding In Low Speed Turns

  • Thread starter Thread starter 91redFox
  • Start date Start date Feb 21, 2016

91redFox

Member
Jan 2, 2014
61
5
19
Bay Area, California
Feb 21, 2016
#1
  • Feb 21, 2016
  • #1
Hey guys,

I recently replaced my rear end. I bought a used, 3.55 LSD from a custom shop in the area. Inspected the rear end thoroughly before buying, all of the gears looked great, almost new, and bearings felt good.

I installed the new rear end last weekend along with a new set of tubular control arms (upper and lower) and new bushings in all connections. Filled the rear end with the correct amount of Royal Purple 75W-140 fluid with friction modifier. I took it out for a drive, and the rear end was quiet and felt smooth in straight lines and in turns. However, as I drove it longer and it heated up, it started making slight popping noises in turns and really bad pooping and grinding at low speeds when the wheel is turned (i.e. In parking lots).

I did a little reading, and concluded that it might be the clutches binding, so I added about 2 more oz of friction modifier. Took it to a parking lot and did figure 8s for a while, dead silent.

I drove it around for a while longer, up windy roads and on the freeway and let it heat up. And, once again, when I started making low speed (<20mph) turns, I get a horrible popping / grinding sound and a binding sensation with no improvement from the previous occurrence.

I put the rear end on jack stands and ran it, letting the wheels spin freely. I listened to the differential carefully, everything sounds smooth with no rubbing or grinding and a minor knock from the driveshaft/ U joint.

Anyone had similar experience with an 8.8? I know the grinding/popping can be normal with limited-slips, but I'm beginning to think the problem might not be coming from the clutch pack.

As always, your help and input is appreciated!
 

91redFox

Member
Jan 2, 2014
61
5
19
Bay Area, California
Feb 21, 2016
#2
  • Feb 21, 2016
  • #2
P.S.-
The car has 12" Baer disc brakes on the rear, if that helps anything.
 

Jason 302

10 Year Member
Aug 9, 2003
685
71
68
Newark, Ohio
Feb 21, 2016
#3
  • Feb 21, 2016
  • #3
What LSD is it? Ford trac-loc? I agree, does sound like the clutch discs are stacked in too tight if that's possible. I would closely inspect your spider gears also.
 

mikestang63

SN Certified Technician
Aug 27, 2012
11,606
8,859
214
In the garage
Feb 21, 2016
#4
  • Feb 21, 2016
  • #4
that and also are the new rear control arms poly bushed? If so did you lube them and torque the bolts with the suspension fully weighted?

Good video on how to setup the clutch packs

 

stykthyn

I want to measure mine. It doesn't look that tall.
15 Year Member
Jul 6, 2006
5,232
2,652
223
gainesville
Feb 21, 2016
#5
  • Feb 21, 2016
  • #5
I'm With mikestang. If you didn't torque the control arms with the wheels level then you have an extreme amount of preload. Couple that with no lube and you have bushings that are literally screaming for mercy.
 

91redFox

Member
Jan 2, 2014
61
5
19
Bay Area, California
Feb 21, 2016
#6
  • Feb 21, 2016
  • #6
Jason 302 said:
What LSD is it? Ford trac-loc? I agree, does sound like the clutch discs are stacked in too tight if that's possible. I would closely inspect your spider gears also.
Click to expand...

I believe It's an eaton posi
 

91redFox

Member
Jan 2, 2014
61
5
19
Bay Area, California
Feb 21, 2016
#7
  • Feb 21, 2016
  • #7
mikestang63 said:
that and also are the new rear control arms poly bushed? If so did you lube them and torque the bolts with the suspension fully weighted?

Good video on how to setup the clutch packs

Click to expand...

They are rubber bushings, I lived them pretty thoroughly on install but I I did not torque the bolts with it loaded... May have to loosen them and give that a try.
 

stykthyn

I want to measure mine. It doesn't look that tall.
15 Year Member
Jul 6, 2006
5,232
2,652
223
gainesville
Feb 21, 2016
#8
  • Feb 21, 2016
  • #8
Jack the car up and loosen them. Then either lower the car to the ground if you can fit underneath or use the Jack to simulate the load. Measure the gap between the fender and the tire while it is on the ground. If you can duplicate that you'll be in the ballpark.
 

91redFox

Member
Jan 2, 2014
61
5
19
Bay Area, California
Feb 21, 2016
#9
  • Feb 21, 2016
  • #9
stykthyn said:
Jack the car up and loosen them. Then either lower the car to the ground if you can fit underneath or use the Jack to simulate the load. Measure the gap between the fender and the tire while it is on the ground. If you can duplicate that you'll be in the ballpark.
Click to expand...


Cool. I'll give that a try tomorrow. Thanks!
 
You must log in or register to reply here.

Similar threads

M
Engine Unexplainable Exhaust Pop and Gurgle
  • Mrnissen122
  • Feb 14, 2026
  • Fox 5.0 Mustang Tech
Replies
12
Views
574
Fox 5.0 Mustang Tech Feb 18, 2026
Noobz347
Drivetrain Rear end clunk
  • seanmahoney
  • Oct 13, 2025
  • SN95 4.6L Mustang Tech
Replies
3
Views
419
SN95 4.6L Mustang Tech Oct 13, 2025
nickyb
Tuners come on inside
  • squeak93
  • Feb 13, 2026
  • SVT Tech Forum
Replies
1
Views
258
SVT Tech Forum Feb 20, 2026
squeak93
S
Engine Stalls when downshifting/coasting
  • Scott_S
  • Nov 5, 2025
  • Fox 5.0 Mustang Tech
Replies
11
Views
725
Fox 5.0 Mustang Tech Nov 6, 2025
Mustang5L5
E
2007 GT Stalls when lights or a/c turned on
  • ejscarfo
  • Jun 22, 2026
  • 2005 - 2009 Specific Tech
Replies
2
Views
137
2005 - 2009 Specific Tech Jun 29, 2026
ejscarfo
E
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?