Close



Results 1 to 14 of 14
  1. #1

    Default Rear axle question

    I just got my '85 GT off the transport truck and realized an issue... The rear axle is locked. if rolling straight forward or reverse the rearend is silent, but when turning there's a racket coming from the back of the car (could just be tire noise). I've verified that the brakes are not dragging. I've verified the parking brake is free. I jacked the car up and the wheels turn easily, but there is no differential action. The wheels turn 1:1 side-to-side (turn the left wheel forward and the right turns forward). I see no leaks from the pinion or cover, haven't pulled a wheel yet, but the rear brakes wok fine, so I'm assuming no leaks t the axle seals.

    Would the trac-loc lock up if there was no friction modifier in the gear oil? Or would it need fresh oil/modifier? I assume that the trac-loc wouldn't engage if the friction modifier was old or nonexistent, or am I wrong, would it stick locked?

  2. #2
    FEP Power Member 86-TC/SVO's Avatar
    Join Date
    Aug 2010
    Location
    Connellsville, Pa
    Posts
    1,024

    Default

    Are you sure it's not an axle bearing ? My Dad's 88' TC had a noise from the rear end and it was an axle bearing.
    86' SVO 1C # 17 of 3379 86's #6475 of 9837
    86' SVO 1C #497 of 3379 86's #6955 of 9837
    84' GT Turbo #4 of 3241 GT Turbo HB's #560 of 3935
    87' Thunderbird TC 1 of 10
    http://www.foureyedpride.com/content...e-of-the-Month

  3. #3
    FEP Power Member Broncojunkie's Avatar
    Join Date
    Jan 2015
    Location
    Barboursville, WV
    Posts
    1,773

    Default

    Doesn't take much to pop the cover off and have a look. Might be really obvious.
    79 Pace Car - 331, t5
    79 Pace Car- 302, 4 spd
    79 Cobra - working on 351w, t5
    82 Capri- working on 302, t5
    82gt - working on 408w, c4

  4. #4

    Default

    Quote Originally Posted by Broncojunkie View Post
    Doesn't take much to pop the cover off and have a look. Might be really obvious.
    I'm trying to avoid removing the cover if all I need to do is add friction modifier...

    Would the trac-loc lock up if there was no friction modifier in the gear oil? Or would it need fresh oil/modifier? I assume that the trac-loc wouldn't engage if the friction modifier was old or nonexistent, or am I wrong, would it stick locked?

  5. #5
    FEP Power Member richpet's Avatar
    Join Date
    Mar 2003
    Location
    Lowell, Oregon
    Posts
    2,136

    Default Rear axle question

    It would be best to just pull the cover and look otherwise. It's pretty easy.
    The modifier might make it quieter is all, it might not.
    Saying it makes a racket is not a good description of the noise.
    I see Accel? Braking? Turning? All the time?
    Last edited by richpet; 05-23-2021 at 10:24 PM.
    83 5.0 GT. Quicker than it looks! 10:1 (or just over) 306, Motorsport a332 cam, 140A alt, t5 conv, 8.8 w/ 3.27's, Edel rpm, alum rad, very worked e7's, Holley SA carb, etc... SOLD IT!!!!

    Now an 1981 Granada! .040 over 302, Edel E-street heads... Currently building a 347 because, why not?

    "Never underestimate the power of stupid people in large groups"

  6. #6
    FEP Power Member Broncojunkie's Avatar
    Join Date
    Jan 2015
    Location
    Barboursville, WV
    Posts
    1,773

    Default

    Quote Originally Posted by TxMike64 View Post
    I'm trying to avoid removing the cover if all I need to do is add friction modifier...

    Would the trac-loc lock up if there was no friction modifier in the gear oil? Or would it need fresh oil/modifier? I assume that the trac-loc wouldn't engage if the friction modifier was old or nonexistent, or am I wrong, would it stick locked?
    Lack of friction modifier won't cause them to lock up. They just chatter, as far as my experience goes. If you're dead set on not pulling the cover if you don't have to, another thing you can check is the pinion bearing. Grab the driveshaft near the rear u-jount and try to move it around. If the pinion has a lot of play in it, the bearing may be toast. If the pinion itself is loose, the ring gear can contact the carrier and cause binding/lock-up.
    79 Pace Car - 331, t5
    79 Pace Car- 302, 4 spd
    79 Cobra - working on 351w, t5
    82 Capri- working on 302, t5
    82gt - working on 408w, c4

  7. #7

    Default

    If the car is new to you, removing the cover is your best bet. No telling what a previous owner may or may not have done.
    79 Zephyr, 4.6L 4v/4r70w swap, with team z front and rear suspension, 8.8 and upgraded brakes and coil overs. Running Holley Terminator X Max.

  8. #8
    Moderator wraithracing's Avatar
    Join Date
    Jun 2010
    Location
    Grand Junction, CO/RR TX
    Posts
    14,206

    Default

    Friction modifier is actually designed to allow the clutch discs to slip more to remove the chattering during cornering that can happen and the associated noise that accompanies it. Friction modifier will actually allow the disc to wear a bit faster (NOTHING EXTREME), but they can wear faster due to the discs slipping more than just locking up and grabbing. No different than constantly slipping the clutch when taking off from a stop.

    With that said, it sounds like something is not right with the differential and I would highly recommend pulling the cover and inspecting as others have mentioned. Hopefully whatever the issue is can be corrected easily and before significant damage occurs. Good Luck!
    ​Trey

    "I Don't build it hoping for your approval! I built it because it meets mine!"

    "I've spent most of my money on Mustangs, racing, and women... the rest I just wasted."

    Mustangs Past: Too many to remember!
    Current Mustangs:
    1969 Mach 1
    1979 Pace Car now 5.0/5 speed
    1982 GT Stalled RestoModification
    1984 SVO Still Waiting Restoration
    1986 GT Under going Wide Body Conversion Currently

    Current Capris:
    1981 Capri Roller
    1981 Capri Black Magic Roller Basket Case
    1982 Capri RS 5.0/4spd T-top Full Restoration Stalled in TX
    1984 Capri RS T-top Roller
    1983-84 Gloy Racing Trans Am/IMSA Body Parts

  9. #9

    Default

    Yeah, I'm not averse to removing the cover, I just don't want to do it if it's just a matter of adding FM. My real intent in asking is to find out the failure mode of the Trac-Lok (slipping or sticking).

    "I see Accel? Braking? Turning? All the time?"

    I've checked under accel, under braking, reverse, forward... If you're going straight its silent. As soon as you start turning you hear tires scrubbing and groaning coming from the rearend.

    I would think if the pinion bearing is loose driveshaft clunking would be heard when shifting into drive, or when loading the drivetrain (like power braking).

    I have an 8.8 out of a '96 but I was wanting to put gears in it before having to swap it in.

    My real challenge is that I use a wheelchair and can't get up/dwn off the ground to work under the car in my garage. I have an arrangement with a local shop to use a lift on the weekends if any are open, but they are stacked-up with work which has kept me from being able to use an open lift. I may need to invest in a lift for my garage.

  10. #10
    FEP Senior Member
    Join Date
    May 2016
    Location
    Lake City Pa 16423
    Posts
    510

    Default

    I'm surprised that no one here mentioned the possibility that you may have a spool in there. No clutch packs or open diff.

  11. #11
    FEP Power Member
    Join Date
    Nov 2007
    Location
    San Mateo, CA
    Posts
    2,271

    Default

    The rear in my 85 was making a lot of noise, snapping and popping. Only required adding of friction modifier.
    Last edited by KevinK; 05-24-2021 at 10:55 PM.
    Fox Body/3rd Gen MCA Gold Card Judge
    84 SVO 24K miles, 85 Mclaren Capri Vert. 84 GT Turbo Vert.
    88 Mclaren Mustang Vert 20K miles, 89 Mustang LX Sport Vert,
    03 Mach 1 7900 miles, 74 Mustang II, 69 Mustang, 67 Mustang, 07 GT500,
    14 Mustang CS/GT, 15 F150 FTX Tuscany, 16 F250 Crewcab, 67 Tbird 47K miles

  12. #12

    Default

    Quote Originally Posted by KevinK View Post
    The rear in m6 85 was making a lot of noise, snapping and popping. Only required adding of friction modifier.
    I'm going to try it. Might as well... might buy me some time while I rebuild my 8.8.

    Quote Originally Posted by dynodon64 View Post
    I'm surprised that no one here mentioned the possibility that you may have a spool in there. No clutch packs or open diff.
    No. This car is a cream puff stock car. And I asked the PO, he said "it was dry" and "sticky". But an older guy who wasn't very mechanically inclined.
    The cars I've driven with spools don't groan like this thing does...

  13. #13
    FEP Power Member Broncojunkie's Avatar
    Join Date
    Jan 2015
    Location
    Barboursville, WV
    Posts
    1,773

    Default

    I misunderstood when you said it was locking up. I thought you meant the rear end itself was binding...as in, something catching and stopping it from rolling.

    I don't think you can tell if the trac-loc is working properly by turning a wheel with the rear tires off the ground. Have you checked the fluid level? I would start there. Dump a bottle of friction modifier in, along with any fluid that needs added. This is in lou of pulling the cover, inspecting, and refilling with fresh oil, of course. (In fact, the first thing I do after buying a used vehicle is change all fluids... even flush the radiator.) I'm sure you do the same, but I totally understand your situation. These are crazy times in the car/repair/service industry... and many other industries. I couldn't even get a dag gone haircut the other day lol!
    79 Pace Car - 331, t5
    79 Pace Car- 302, 4 spd
    79 Cobra - working on 351w, t5
    82 Capri- working on 302, t5
    82gt - working on 408w, c4

  14. #14

    Default

    Sounds like a spool. I hate removing covers too, but it's not that bad. Plus, you'll really know what's going on.
    Theodore J. Garbera, 1985 Mercury Capri RS

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •