Dread Terminator Clunk after IRS swap ~ HELP!!

[cobralvr01]

So some of you guys may have seen in these threads that I finished an IRS swap recently. I've recently been experiencing a clunk noise when shifting while both at a standstill and cruising. I also have alot of drivetrain noise going on while going 40+mph.
I just checked a couple of nights ago to see if anything was loose. Sure enough, ALL the subframe bolts were loose probably due to the unit shifting into place. I tightened those down as much as possible. I check the front pumpkin bolts and they were somewhat loose too, so I tightened those down to spec. I checked for anything else that may be loose, but there's nothing left. I didn't adjust the driveline angle.
I was able to mimic the clunking sound by raising up the rear end, lying down right in the center of the car under the gas tank, grabbing the wheels on both sides and rotating them back and forth. It sounded like it was in the center pumpkin and continuing into the drive shaft. I have an aluminum driveshaft so the sound is very pingy and loud.
Is this the infamous Terminator clunk sound I'm experiencing? If it is, is there any cause for concern or any ways to get rid of it? Could it be my driveline being out of alignment that would cause this?

IRS Specs:
Terminator #1 30k miles:
Pulled IRS unit
DSS Level 5 half shafts (removed because they're too robust for my application)
blown up center pumpkin
FTBR delrin bushings on control arms, subframe, front & rear diff mounts.

Terminator #2 30k miles:
1 cv axle (replaced 1 DSS halfshaft)
New Ford Racing bearing

Terminator #3 50k miles:
1 cv axle (replaced 1 DSS halfshaft)
New Ford Racing bearing

Terminator #4 30k miles :
Center Pumpkin (never cracked open...I put in new Royal Purple fluid in as well)

 

[redrocket16]

From what I understand the infamous clunk is from the T56 and not the IRS. That's where my sounds come from at least and not my IRS. Depending on your wheel/tire combo it could be rubbing your fenders as mine did. Occasionally I bottom out and I have to be careful about that to the point it's worn off paint on the inside of the rear bumper.

 

[brucesvt]

when i did my swap thats what mine started doing. I got in contact with Bruce from Full Tilt. He told me my carrier bushings for the differential where old and worn. I ordered the bushing kit and no more clunking sound.

Hope this helps

 

[redrocket16]

That could be Bruce, I installed FTBR on mine before I installed it so I never had the pleasure of stock bushings.

 

[cobralvr01]

I had already replaced all of diff support bushings with the delrin option.:shrug:

 

[Cobragixxer9994]

Check the knuckle bushings thats what mine was also check the rear diff mount mine loosed up causing alot of play

 

[cobralvr01]

Check the knuckle bushings thats what mine was also check the rear diff mount mine loosed up causing alot of play

If it's the knuckle bushings what would be the remedy for that? With the mounts, are you talking about the mount that is near the diff cover, or the mounts near the diff pinion flange? I recently tightened down the front, could it be the rear mounts for the diff?

 

[Cobragixxer9994]

the knuckle bushings would need replaced also heres a picture of the rear diff mount the bolt that needs to be tightened id the bolt that mounts it to the subframe

 

[cobralvr01]

Ok, I don't think it's the knuckle bushings because when I was under the car rotating the wheels back and forth, the sound was coming from the diff. I'll check the rear diff brace. Hopefully that's it. It didn't do this until after a couple of weeks from hard driving through the canyons. Hopefully it just wiggled loose a bit...thank you. I'll report back in a few days.

 

[BOOOSTD]

I'm fighting the same battle as you - I think my diff is gone though. I posted some videos into my thread. Have a look and let me know if it's the same.

 

[cobralvr01]

Yep that's the exact same issue I'm having. I also have already checked the same things you checked. Idk what's wrong with it at this point.

 

[2DXTRM]

After seeing what BOOOSTED went through, (check his thread here: http://www.svtperformance.com/forum...50M-and-5001-combo-Clunk-Questions&highlight= ), I went and double checked mine. Lo and behold I ****ed up in the install (4 years ago! I hardly drive my car) on the diff. bushings as I was getting a clunk as well.

Drove it last night for the first time in a month and I forgot how annoying that shit was. Got the car up on jacks today and I found my problem. I had kept the stupid dogbone/NVH damper. If you still have it, get rid of that shit and orient the bushings/shims as shown in this FTBR picture below. Problem solved (for me)!!!


PICTURES sourced from FTBR website.

 

[cobralvr01]

Unfortunately, I didn't put that back on after my FTBR install so that's not causing my problem.

 

[Mystic-SVT]

Remove the bolts that hold the IRS cradle to the body at the lower mounting points (where the lower control arm on SRA bolts to the body). Let the IRS drop down enough to where you can stick the bolts back in through the bushing sleeve and check for play. If there is play then that's your problem making the thump sound. Replace them with grade 8 9/16 (14mm ). You'll have to drill out the hole in the body also but it's not much, it's easy and fast bc it's just a hair too small. Full Tilt Boogie has those bolts in stock also in case you don't feel like going on a hunt for them.

 

[cobralvr01]

Remove the bolts that hold the IRS cradle to the body at the lower mounting points (where the lower control arm on SRA bolts to the body). Let the IRS drop down enough to where you can stick the bolts back in through the bushing sleeve and check for play. If there is play then that's your problem making the thump sound. Replace them with grade 8 9/16 (14mm ). You'll have to drill out the hole in the body also but it's not much, it's easy and fast bc it's just a hair too small. Full Tilt Boogie has those bolts in stock also in case you don't feel like going on a hunt for them.

Those already come with the kit I purchased and are already in there.

 

[brucesvt]

Has the issue been fixed OP? i am in the process(if i can ever get a day off lol) of purchasing a 97 cobra with a IRS from phoenix. I will be checking this thread for ideas.

 

[2DXTRM]

Has the issue been fixed OP? i am in the process(if i can ever get a day off lol) of purchasing a 97 cobra with a IRS from phoenix. I will be checking this thread for ideas.

congrats man! hope you get it!

 

[cobralvr01]

Has the issue been fixed OP? i am in the process(if i can ever get a day off lol) of purchasing a 97 cobra with a IRS from phoenix. I will be checking this thread for ideas.

It's the monsoon season in Phoenix and getting out in the garage is murder right now.

 

[cobralvr01]

Bringing this nightmare back from the dead. So I haven't driven the Cobra since the last post because I bought a G37S. The Cobra's basically been sitting in the garage since. So I jacked the Cobra up, engaged the e-brake, and did some tracing. Well, I took the exhaust out, still clunking. Disconnected the driveshaft, the clunk still happens when I rotate the wheels back and forth and the gears don't engage until about 5-7 degrees of rotation, so I took that off. It's looking like it's down to play in the cv axles, in the differential, or a sum of both. I ended up taking out the cv axles and the center pumpkin. The backlash in the differential is around 0.023"-0.024" and when I rotate the pinion flange, there's a decent amount of noise. I think I'm looking at a full rebuild at this point. Anyone know if this backlash is acceptable and this slack is just normal at this point?

2 hour later

Turns out you can use a blown up IRS pumpkin as a makeshift stand.

 

[cobralvr01]

Bringing this back from the dead. I sent my center diff to get it rebuilt and it's mounted in the car. I will put in the axles tomorrow and everything. I also sent my aluminum driveshaft to get it shortened. There was no clearance to get this over the pinion nut.