Drivetrain CLUNK! YES or NO.

[TR10thACoupe]

My opinion.

In the past I owned a 97 Cobra with the T-5 and constantly complained to the dealership about this "clunking" I was experiencing with sounding nothing short of a driveline slap problem.

However, I as well experience this same noise in my 03, but there is better logic behind the noise in the T-56 than was in the T-5.

Hypothetically but educated, the gears are unshaven and ridged for the ability to handle high loads of torque stress, time after time.

I would like to thank CuLaTeR for the Service Bulletin I will defintely bring up my awareness of them.

Glad to see something is finally getting done about this.

36k and 40 years of practice???:shrug: :shrug:

Thanks

TR10thACoupe

 

[PowerWheels]

I think everyone has it, it's just the way you shift.

 

[03_Sonic Blur]

Mine would be clearance in the transmission. How do I know? I installed the Metco D/S loop, and checked the rear and tranny for "Clunk" while the D/S was off. The tranny won

 

[4.6speed]

The "clunk" is normal, it's the "snap" that you have to worry about!

 

[venomus 03]

It goes away with smooth shifting for me

 

[PowerWheels]

No it's the POW/KRANG you need to worry about!

 

[kevkno]

Hello folks. New to this forum but not new to Mustangs.

Please, Please understand that the "clunk" should NOT be considered "normal". I don't care how many Cobras have the problem. It just means they ALL need to be repaired.

I bought my Cobra used in Jan 2002 and noticed the problem right away. I bought into it being "normal" for a few months until a component in the rear suspension gave out and punched a hole right through the differential. It was the square looking bracket with the differential bushing in it. They replaced that bracket/bushing and the gears/diff cover. After that repair (July 2003) no more clunk at any speed or any gear. You could cruise along in 5th, give it some gas and no more clunk. However, the problem came back 4 months later. Same familiar symptoms. It felt really sloppy and loose. I thought the rear could go at any time, like the last time. I lived with it for about a month but didn't want to get stranded so, I took it in for my 30k svc this week. I told them about the problem and they said they would look at it. It get's a little weird here but they kept the car for 2 days. They did the 30k svc which should only take a couple of hours and said they looked and road tested the car but didn't see or feel any clunking. No arguement from me. I took the car back determined to break it so they could actually have something to fix but when I got the car back......It wasn't clunking anymore. It feels like a NEW Cobra should feel. Everything feels tight. I can shift like you are supposed to shift a Cobra...Hard! No clunking at any gear regardless of speed and application of gas. SO, THEY DID SOMETHING!. I just don't know what and I really don't care. The car works like it should now. Oh yeah...."CLUNKING" IS NOT NORMAL!!!!

 

[The Orphaner]

Hi all, I know i'm new to this site, since having traded in my 01 L for the 03 Cobra, but having worked for Ford as an engine mechanic for a few years have any of you tried packing the driveshaft? We use to do it on ranger 4X4's to get rid of the driveline clunk. If you packed the front yoke with grease where it splines onto the trans....it may help reduce/eiliminate the clunking sound. Just my .02. And if this was already mentioned, sorry, this post was way to long for 3 a.m. LOL. :sleeping:

 

[jimh]

Is the drive line clunk normal? Yes and No.
Yes, because some clunk is normal on a heavy duty trans and rear car. People see it more on the Cobra because from the factory the clutch is adjusted to grab down by the floor instead of up near the top of the pedal travel like most cars. It happens because yuor foot is not trained to give it gas early enough and as the clutch engages there is a moment of deceleration moving the torque to the other side of the gears in the drive line then sundenly back to the acceleration side. That's why you read a lot of "It went away once I learned how to frive the car." The clunk comes from the backlash in all of the components in the drive line. My guess would be that the IRS may even be a little worse because there are basically 6 yokes in the drive path. If I didn't shift right in my GT it clunked. When I got into the Cobra it clunked and felt like it was my first time driving a stick. Once I got used to gassing it a little earlier no more clunk. Also you have to remember that the IRS diff is mounted to the chasis and clunks and noises will me transmitted directly through the chasis instead of partially being absorbed by the springs.

Now for the "no it's not normal" part...
No, it's not normal on the Cobra because on some Cobras there is an excessive amount of clunk. This comes from a couple of things. On some Cobras the diff needs to be retorqued. The diff on our cars is mounted to a brace on the chasis and not the springs. If this loosens up the diff will move under a load and cause a clunking. Depending on how loose it gets and how much it moves it will also through off the geometry and can cause breakage. Some Cobras also have poorly machined spindles that cause a click or pop under certain conditions. These are fixed by replacing the spindle and half shaft.

kevkno's last problem probably cleared up because they retorqued the diff.

Once you are used to driving the car you really should't get any clunking. Having the clutch grab so low is always tricky.

just my .02

jim

 

[bassin247]

I swapped out my IRS for a solid axle and the clunking is GONE! THANK YOU GOD!!@#%$+)*_)(&$

 

[Brucealeg]

My 01 GT had the clunk big time. The 03 Cobra has it, but it's MUCH better then the GT. It's a rare noise and not as loud as the GT. I really thought there was something wrong with the GT because of it.

Bruce

 

[olchakla]

I installed my long subframes and replaced the bushings and the rear end clunk became very pronounced. I maybe never noticed it too much but when I had the strpped in for a dyno run, it was really noticable.

They put the car up on the lift and it seems that I have excessive slack between the drive shaft and differential.

I taking my car in next week to the dealer and have them repair the problem and remove the extra slack. I know that if I get on it too hard that all that extra play will cause something to break. I already had to have the inspection cover, front housing and drive shaft replaced when the bracket mounting the differential to the frame sheared off when it took too hard a shock of torgue.

 

[03soniccobra01]

My o3 has 5600 on it now and it cluncked since I brought it home.
I to have learned to drive so that I don't even hear or feel it anymore. If it is to bad you must have the 8.8 re-built. I am going to run her till she blows.....

 

[2814v]

So if you replaced your rear gears 3.90, 4.10 etc. and it was done correctly would you still clunk? Or maybe alittle less? If it would fix the clunk I would go with 3.90's.

 

[RedfireVert]

I guess I got lucky...My Cobra's at 6,300 miles with no clunk, pop, vibe, pull, or tick. It does have the "rub" (seat rub) on the passenger side though...

My LX 5.0 never had the clunk. All three T-5 trannies never clunked, at least not before they were broken. :shrug:

 

[oldnfast]

Clunks, wheel-hop, moving shifters....
Guys, this is a performance car. You have to LEARN HOW TO DRIVE IT !! Each one is a little different. Yes, the shifter moves. It moves the direction the drivetrain is turning. Look at a picture of a car doing a wheelie. One front wheel is higher than the other one. Your drivetrain is trying to turn your car on it's side. It's called torque, and you have plenty of it. Wheel-hop is a lead foot overpowering the available traction (even John Force can do it). For the most part, the clunk is caused by a lack of "give" in the driveline (nothing to dampen the heavy-toothed gears hitting each other). No clunk, less RWHP.
:thumbsup:

 

[3GROC]

Originally posted by oldnfast
Clunks, wheel-hop, moving shifters....
Guys, this is a performance car. You have to LEARN HOW TO DRIVE IT !! Each one is a little different. Yes, the shifter moves. It moves the direction the drivetrain is turning. Look at a picture of a car doing a wheelie. One front wheel is higher than the other one. Your drivetrain is trying to turn your car on it's side. It's called torque, and you have plenty of it. Wheel-hop is a lead foot overpowering the available traction (even John Force can do it). For the most part, the clunk is caused by a lack of "give" in the driveline (nothing to dampen the heavy-toothed gears hitting each other). No clunk, less RWHP.
:thumbsup:

I agree with you. on the other hand there is such a thing as excessive. I Didnt read the whole thread so Im sorry if someone said that already.

I had my DS replaced due to what I thought was excessive play in the driveline which seemed to result in a massive clunk when at highway speeds lifting off and gently getting back on it at speed. I only asked my dealer about it and we put it on a lift and sure enough there was a ton of play. they got me a new one and put it in and showed me how much less play there seemed to be. it still clunks and I can get it to clunk but it doesnt do it all the time like it used to

Im happy now tho....the whole car doesnt feel like it is gonna explode anymore when I get back in the throttle in light traffic anymore

 

[oldnfast]

You're right Chris. I can speak only for the half-dozen '03s I'm familiar with (including mine). None of us had "excessive" clunk. Now that we've put a few thousand miles on our cars, we seldom get the "clunk" (although it still happens when we have a brain-fart & forget what we're driving - it ain't no Civic). Yours sounds like it was really bad. I had one of the first 4.0 Ranger Edge's that had a short drive-shaft (BIG clunk).

 

[3GROC]

Originally posted by oldnfast
You're right Chris. I can speak only for the half-dozen '03s I'm familiar with (including mine). None of us had "excessive" clunk. Now that we've put a few thousand miles on our cars, we seldom get the "clunk" (although it still happens when we have a brain-fart & forget what we're driving - it ain't no Civic). Yours sounds like it was really bad. I had one of the first 4.0 Ranger Edge's that had a short drive-shaft (BIG clunk).

I thought it was me when I First got it but I had owned 2 t56 transed cars before...so I knew how it shifted and everything...

such as my Camaro SS before this one. loud as hell. alum driveshaft....373 straight cutgears....at highways speeds..it would go WEEEEEEEEEEEEEEEE....sucked but strong


I will take the lil clunks and rattles....the only thing with my cobra now is the dreaded tick. that is why it is at the dealer now...

other then that Im all for crudeness. its usually the best

 

[fusion_ta66]

Originally posted by oldnfast
Clunks, wheel-hop, moving shifters....
Guys, this is a performance car. You have to LEARN HOW TO DRIVE IT !! Each one is a little different. Yes, the shifter moves. It moves the direction the drivetrain is turning. Look at a picture of a car doing a wheelie. One front wheel is higher than the other one. Your drivetrain is trying to turn your car on it's side. It's called torque, and you have plenty of it. Wheel-hop is a lead foot overpowering the available traction (even John Force can do it). For the most part, the clunk is caused by a lack of "give" in the driveline (nothing to dampen the heavy-toothed gears hitting each other). No clunk, less RWHP.
:thumbsup:

I have to respectfully disagree with this. I have owned several performance cars, and none of them clunk. If the drivetrain is set up properly, there should be no clunk. My 65 chevelle (500+ horsepower), has no clunk at all, and uses parts from the 1960's! The heavy-toothed gears shouldn't be 'hitting' each other, they should be already pressing against each consecutive tooth without any power applied. Is this car a good deal? Yes. Is it powerful? Yes. Does that mean that all of a sudden drivetrain slack is OK? No.