Excessive driveline play/ is this the "cobra clunk" (videos inside)

[CarolinaCobra]

I have what I always thought was the "cobra clunk" but I'm beginning to think it's something else. I have a couple videos below that show the amount of play in what looks like the trans and possibly rear end as well. I always thought my "clunking" during shifts was the rubber bushings but they all look to be polly and pretty new and I couldn't get the rear diff to move at all while it was on jack stands.

Is this just all the backlash in the drivetrain adding up?
Is this a normal amount?
I can drive around it but it takes so much effort and it really makes this car less enjoyable to drive.

[nomedia="http://www.youtube.com/watch?v=m-0CXQtRVqA"]YouTube - MVI_0230.AVI[/nomedia]
[nomedia="http://www.youtube.com/watch?v=UvxwXQRn1Zc"]YouTube - MVI_0231.AVI[/nomedia]

 

[SonicBlueOval]

are you in gear when doing that or is the trans in neutral

 

[red351wcobra]

My car does the same thing. It's very annoying.I figured I need to have the rearend rebuilt.. None of my other cars have had this amount of play.

 

[CarolinaCobra]

are you in gear when doing that or is the trans in neutral

I was in gear with the parking brake on as well.

 

[Othic]

I have the same problem too. Ive spent more money on trying to fix this problem than upgrades on the car. Here are the things Ive tried but with no improvement at all.

-Trans stripped down (professionally, not me) and check-Installed 26T input, syncros, and solid shift keys while apart.
-Full Tilt Boogie Racing kit with 9/16 subframe bolts. Checked rear end backlash while IRS was out. That was ok
-2 brand new cv axles from ford.

The next step is a T56 Magnum

Now that I think of it, most of that stuff is upgrades. But that wasnt why I bought all that stuff. My car is my daily and is getting so annoying. That new 5.0 is looking better and better every day.

 

[CarolinaCobra]

I have the same problem too. Ive spent more money on trying to fix this problem than upgrades on the car. Here are the things Ive tried but with no improvement at all.

-Trans stripped down (professionally, not me) and check-Installed 26T input, syncros, and solid shift keys while apart.
-Full Tilt Boogie Racing kit with 9/16 subframe bolts. Checked rear end backlash while IRS was out. That was ok
-2 brand new cv axles from ford.

The next step is a T56 Magnum

Now that I think of it, most of that stuff is upgrades. But that wasnt why I bought all that stuff. My car is my daily and is getting so annoying. That new 5.0 is looking better and better every day.

Well that's disappointing news. Thanks for the help though.

 

[03Snake04]

the dreaded irs slack .. ugh

 

[*Jay*]

In for info, my DS has just as much play in it. When pushing the clutch pedal (if im not careful) during "stop and go" traffic that "play" will make the DS bounce back and forth causing a knocking/rattle sound.

 

[CarolinaCobra]

In for info, my DS has just as much play in it. When pushing the clutch pedal (if im not careful) during "stop and go" traffic that "play" will make the DS bounce back and forth causing a knocking/rattle sound.

Yeah I have the exact same issue. That combined with the clutch chatter I have make stop and go traffic really painful. I hope in the 8+ years this car has been out that someone has figured this out. I know the answer is out there.
And before anyone says it... no I'm not getting rid of the IRS for a SRA.

 

[perry2k12]

It's like you were under my car wiggling the driveshaft... Mine is just as bad if not worse. When I first drove the car I almost didn't buy it because of the noise. I solved the problem with an o/r midpipe and 3" catback haha. But I'm afraid my rear end is going to explode one day.

 

[cobracide]

14mm IRS subframe bolts help the drivetrain slack issue (for me) - it does not solve the issue.
I think these are it, check with MM
http://www.maximummotorsports.com/store/index.php?main_page=product_info&products_id=1369

Also, upgraded differential bushings, MM IRS subframe bushings.

Check this:
http://www.svtperformance.com/forums/new-edge-cobras-51/213384-irs-tech-article.html

 

[CarolinaCobra]

14mm IRS subframe bolts help the drivetrain slack issue (for me) - it does not solve the issue.
I think these are it, check with MM
14mm hardware kit for IRS subframe & RLCA mounting, 1999-04 [MMF-4] : Maximum Motorsports, the Latemodel Mustang Performance Suspension Leader!

Also, upgraded differential bushings, MM IRS subframe bushings.

Check this:
http://www.svtperformance.com/forums/new-edge-cobras-51/213384-irs-tech-article.html

Thanks for the info. 14mm bolts are next on the to-do list.

 

[SonicBlueOval]

if you are in gear with the e-brake on it seems like the pinion depth is set too shallow or there has simply been too much wear on the ring and pinion teeth. Have you had any work done on the diff? Had any aftermarket gears installed?

 

[keith89]

I have the same thing. It's definitely not bushings because the tranny and differental are not moving on the mounts. It's simply the driveshaft moving by hand. I have a truetrac differential and told it was the worm gears locking up. I think it's the pinion depth was not set correctly or a solid spacer needs to be used instead of a crush sleeve.

 

[Fast GTO]

I have the same issue and recently had the diff rebuilt with gears and tru trac as well as the trans upgraded.. Rear end builder said he got the lash tightened better than spec so not sure why it is still doing it.

 

[SonicBlueOval]

I have the same issue and recently had the diff rebuilt with gears and tru trac as well as the trans upgraded.. Rear end builder said he got the lash tightened better than spec so not sure why it is still doing it.

Yeah, thats really strange then

 

[CarolinaCobra]

Yeah mine supposedly had the rear end rebuilt right before I bought it. I'm thinking they either didn't actually go into it or they didn't do a very good job. I guess I'll just have to live with it until I can afford to have someone take a look at it. It's certainly discouraging to hear that so many other owners have this same problem even with brand new or freshly rebuilt parts.

 

[Fast GTO]

I don't really notice it from a stop...

 

[Fast GTO]

no solutions?

 

[keith89]

I have the same issue and recently had the diff rebuilt with gears and tru trac as well as the trans upgraded.. Rear end builder said he got the lash tightened better than spec so not sure why it is still doing it.

I was told it was the worm gears inside the truetrac winding out. I'm going to try some redline shockproof oil instead. I've heard that helps a lot. I have been told the truetracs are noisy if you use synthetic gear oil because it is too slick for the worm gears.