FTBR 1350M and 5001 combo - Clunk Questions?

[ac427cobra]

Sorry, I'm a newbie IRS guy and not sure which one is the welded nut :bash:
Could someone please post (if possible) a pic of where this welded nut is? I'm starting to really miss my SRA

Thanks guys!

I don't think that this is a real huge problem but I had it as well. What happened in my case was the rear diff mount bolt that attaches the rear diff support to the subframe came loose. Once this bolt comes loose, the small factory weld on the nut does not stand a chance. Below is a pic.

Inside that opening where you see the shank of the bolt is where the rear diff support is bolted to the subframe.

If you have someone in the car loading the drivetrain both forward and rearward with the service brake on, you should be able to peek under the car and see the differential housing moving as it's being loaded.

Hope that helps.

 

[BOOOSTD]

I don't think that this is a real huge problem but I had it as well. What happened in my case was the rear diff mount bolt that attaches the rear diff support to the subframe came loose. Once this bolt comes loose, the small factory weld on the nut does not stand a chance. Below is a pic.

Inside that opening where you see the shank of the bolt is where the rear diff support is bolted to the subframe.

If you have someone in the car loading the drivetrain both forward and rearward with the service brake on, you should be able to peek under the car and see the differential housing moving as it's being loaded.

Hope that helps.

Thanks Bruce for posting the pic; it's very helpful!!

 

[ac427cobra]

Thanks Bruce for posting the pic; it's very helpful!!

Forgot to mention that photo is AFTER we rewelded it. Maybe that was obvious?

 

[BOOOSTD]

Forgot to mention that photo is AFTER we rewelded it. Maybe that was obvious?

That I could tell Lol, gonna check that nut out this weekend.

The more trouble shooting that I'm doing; the more I'm starting to think my diff is gone :cuss: I'm considering the T2 Torsen - thoughts??


Appreciate everyone's input!!

 

[BOOOSTD]

Checked out the welded nut today and its was all good; so that's ruled out.

 

[ac427cobra]

Checked out the welded nut today and its was all good; so that's ruled out.

Have an assistant load the drivetrain in forward and reverse with the service brake applied while you watch for anything moving in the IRS.

 

[BOOOSTD]

Have an assistant load the drivetrain in forward and reverse with the service brake applied while you watch for anything moving in the IRS.

Have a buddy coming over tomorrow to give me hand with that. Thanks for the continued support!

 

[BOOOSTD]

Have an assistant load the drivetrain in forward and reverse with the service brake applied while you watch for anything moving in the IRS.

Did this yesterday with a buddy and both him or I didn't see anything moving in the IRS but could here the clunk.

I've also noticed the clunk seems to be getting worse and is occurring now when I downshift approaching a corner to sweep it. Looks like its time to order the Torsen T2 and have it ripped apart again

 

[ac427cobra]

You may want to try the Dynamat trick first:

http://fulltiltboogieracing.com/faqs.htm#NVH_increase

 

[BOOOSTD]

You may want to try the Dynamat trick first:

http://fulltiltboogieracing.com/faqs.htm#NVH_increase

Noted and I will do it, but I would like to address the clunk first as its sounds like its getting louder. Thanks!

 

[BOOOSTD]

I've been busy with work so had to push the car aside for a a bit, but I finally took a couple videos for some feedback. I think my diff is gonzo!! What u guys think??


Sorry about the videos, had my nephew recording in the wrong aspect; better than nothing.



Can hear clunk good in this one:
https://vimeo.com/173252447



Turning DS by hand:
https://vimeo.com/173252351




Watching tranny movement:
https://vimeo.com/173252701


Tranny movement using prybar:
https://vimeo.com/173252847

 

[ashleyroachclip]

When I have my car , like yours , in the air, both wheels turn .
I notice that is not your case .

After installing an 01 Cobra IRS into my 91 Coupe I will never go back .

 

[ac427cobra]

I would have preferred to see a video with the brakes applied and loading the drive train in both forward and reverse.

You will see a bit of free play in the diff turning only one wheel back and forth.

The trans mount looks ok.

A differential is a maintenance item. Cobras and Cobra drivers have a tendency to be a little hard on their differentials. Depending on how many miles are on the diff and how much the noise is bothering you, you might want to start with a diff rebuild because you're going to need it sooner or later.

Sorry I could not have been of more help.

:thumbsup::coolman:

 

[MG0h3]

FWIW, I only had the typical cobra clunk from the front subframe bolt and that was cleared up after the kit install. If you didnt have it before, something changed during the install.

The video of you turning the DS is how I would describe every vehicle Ive ever worked on. When you turn the DS like that, alot of things have to take up some slack to get the tire moving--pinion>ring>spider/side gears>axles.

As far as your diff being "bad", its a serviceable item with clutches that can wear out. Other than physically breaking a hard part which I suspect you would have seen, Ive never known worn clutches to make noise. You just wont get as much bite, if any, out of the left tire.

The main thing I see moving and making noise is your exhaust so you might want to look into that. Ive also done the test you were doing on the stands while letting the clutch out but for different reasons, and there was definitely more noise/clunk then when the car was on the ground. With no resistance you tend to almost dump the clutch.

As with all mods, if a problem rears its head that wasnt there before, go over everything that you changed FIRST before looking for some unrelated problem.

 

[BOOOSTD]

I would have preferred to see a video with the brakes applied and loading the drive train in both forward and reverse.

You will see a bit of free play in the diff turning only one wheel back and forth.

The trans mount looks ok.

A differential is a maintenance item. Cobras and Cobra drivers have a tendency to be a little hard on their differentials. Depending on how many miles are on the diff and how much the noise is bothering you, you might want to start with a diff rebuild because you're going to need it sooner or later.

Sorry I could not have been of more help.

:thumbsup::coolman:

Hard to get video when the car is on the ground as its pretty low. Best case scenario wud probably be a pit. Thanks for the input!

FWIW, I only had the typical cobra clunk from the front subframe bolt and that was cleared up after the kit install. If you didnt have it before, something changed during the install.

The video of you turning the DS is how I would describe every vehicle Ive ever worked on. When you turn the DS like that, alot of things have to take up some slack to get the tire moving--pinion>ring>spider/side gears>axles.

As far as your diff being "bad", its a serviceable item with clutches that can wear out. Other than physically breaking a hard part which I suspect you would have seen, Ive never known worn clutches to make noise. You just wont get as much bite, if any, out of the left tire.

The main thing I see moving and making noise is your exhaust so you might want to look into that. Ive also done the test you were doing on the stands while letting the clutch out but for different reasons, and there was definitely more noise/clunk then when the car was on the ground. With no resistance you tend to almost dump the clutch.

As with all mods, if a problem rears its head that wasnt there before, go over everything that you changed FIRST before looking for some unrelated problem.

The noise you hear is coming from the diff and sounds the same when its on the ground loaded up. Nothing from the exhaust is touching or rattling. I double checked all the IRS bolts and made sure they were all torqued down. Thanks for reply!

When I have my car , like yours , in the air, both wheels turn .
I notice that is not your case .

After installing an 01 Cobra IRS into my 91 Coupe I will never go back .

Thanks for reply!

 

[Stage 4.6]

Iam in a similar situation as you OP, have had an annoying clunk although mine don't seem as loud as yours, I kind of narrowed it down to excessive backlash in the rear end.

I been wanting to rebuild my diff but have had other priorities sneak up on me lately, I figure as long as I don't launch it hard and baby it for now it'll last for a while.

Mine also has an inconsistent pop (only in reverse) when I am backing my car up on my drive way?

 

[N/Angel]

subscribing to see what you guys find out, I have a new clunk while driving but not consistent, sometimes it's really loud and sometimes it's not there at all. Seems to happen most when driving slow and changing gears.

 

[cobralvr01]

This is the exact same noise my IRS swapped 97 cobra is doing. I just got under it today to see if there was anything loose but all is good and snug. I have the same noise and it is def. coming from the diff. housing. I hope I don't have to rebuild this thing. I've already spent too much on rebuilding and swapping my IRS.

 

[BOOOSTD]

Iam in a similar situation as you OP, have had an annoying clunk although mine don't seem as loud as yours, I kind of narrowed it down to excessive backlash in the rear end.

I been wanting to rebuild my diff but have had other priorities sneak up on me lately, I figure as long as I don't launch it hard and baby it for now it'll last for a while.

Mine also has an inconsistent pop (only in reverse) when I am backing my car up on my drive way?

subscribing to see what you guys find out, I have a new clunk while driving but not consistent, sometimes it's really loud and sometimes it's not there at all. Seems to happen most when driving slow and changing gears.

This is the exact same noise my IRS swapped 97 cobra is doing. I just got under it today to see if there was anything loose but all is good and snug. I have the same noise and it is def. coming from the diff. housing. I hope I don't have to rebuild this thing. I've already spent too much on rebuilding and swapping my IRS.

I was hoping that I wouldn't have to go back in the diff, but its time to get a new diff and move on. I will update once its completed. Thanks for everyone's input!!!

 

[2DXTRM]

subscribing to see what you guys find out, I have a new clunk while driving but not consistent, sometimes it's really loud and sometimes it's not there at all. Seems to happen most when driving slow and changing gears.

This is the exact same noise my IRS swapped 97 cobra is doing. I just got under it today to see if there was anything loose but all is good and snug. I have the same noise and it is def. coming from the diff. housing. I hope I don't have to rebuild this thing. I've already spent too much on rebuilding and swapping my IRS.

What differential are you guys using in your cars? Stock FORD Carbon clutch packed Trac-LOKs?