I just bought an 04 Cobra and when i shift gears normally, it feels as if im taking up a decent amount of driveline lash or slack in the tranny or rear end. If i let go of the clutch very slowly and am completely linear with the throttle, i can take up this "lash" (?) slow enough to be inaudible. I've heard several theories and guesses as to why this occurs, but i think a thread dedicated to this common problem is in order. Please refrain from guessing, as there are plenty already in other places/forums. Also, what can be done to stop this "clunk"?
Couple things you may want to check is make sure your diff flange is tight, get an impact on it I believe it's a 27mm 6 side, mine was loose at one point and I had some thunk and at-speed vibration, then make sure your driveshaft bolts are tight to the flange, this also happened to me and it'll cause the same thing.
Besides your clutch or synchros there really isnt anything else that can go bad unless you have a very odd specific problem but you'd have to give us a COMPLETE detailed report on whats been done to your drivetrain, every little thing.
Inherently though the cobra T56 is very notchy and tends to engage power with a slight clunk though it shouldent be to the point of annoyance. I would stick either royal purple or redline tranny fluid in it, at the cost of 50$ and an hour or so of your time it'll greatly reduce tranny issues.
as an added note, i noticed something else about the problem today. When im coasting to a stop in neutral, with the clutch engaged, and depress the pedal again to put it in 1st, as soon as the shift fork locks up first, i hear the same clunk... doesn't make a lot of sense, someone said the clutch may be out of line, but i'm clueless as to how this is possible seeing as the input shaft will only go through the clutch disc one way and the pressure plate only mounts one way. any ideas?
Mine does the exact same thing. The remedy is once again smoothness. Don't depress the clutch and slam it into first from a stop, depress the clutch and slowly ease it into first. The alternative - checking/fixing/replacing about 100 different little things in your entire driveline and IRS. For instance, I got new tires yesterday and it actually changed how much my car clunks in higher gears. Quite the conundrum this.
when you let the chassis coast ahead of the drivline (take up the slack in the driveline while coasting in gear with clutch engaged) and then hit the accelerator again, not abnormally hard, just enough to take up the slack again, i hear that same clunk. its volume is totally dependent on how much gas i give it and, obviously, what gear im in. I'm beginning to think that the slack in the driveline is an issue from the factory. Perhaps there is a common problem in the terminators that is possible to fix, with proper diagnosis. the "smootheness" that mu22stang was referring to is still coming to me. the car drives differently than my 91 vert, but im getting used to it. i've tossed around the idea of the bushings assosiated with the IRS might be worn out and there's too much play around the differential. IMHO, Ford would have a hard time expaining this noise to consumers in 2003 and 2004, so i dont think it has always been this bad. I mean, it's tolerable, but annoying. and i'm anal about this car. comments/suggestions?
[quote=desert_gypsy;7882799]when you let the chassis coast ahead of the drivline (take up the slack in the driveline while coasting in gear with clutch engaged) and then hit the accelerator again, not abnormally hard, just enough to take up the slack again, i hear that same clunk. [quote]
that's normal...normal for a manual mustang anyway
Quote:
i've tossed around the idea of the bushings assosiated with the IRS might be worn out and there's too much play around the differential.
changing the bushings will do very little, unless yours are trashed..
you could tighten up the backlash but I'd be surprised if it helps very much..
I'm beginning to think that the slack in the driveline is an issue from the factory. Perhaps there is a common problem in the terminators that is possible to fix, with proper diagnosis.
You are exactly right. There is a pole on here somewhere, I think in the archive section, for people with driveline clunk. About 70-75% of Terminator owners on here have it. Worn differential bushings can definately be the culprit, but so can a slew of other IRS bushings. Same for gear backlash and tolerance buildups in the driveline itself. Chances are, if you've driven a Mustang before you've felt it. But, with the IRS pumpkin bolting straight to the chassis, you feel/hear in the passenger compartment much more. Fret not though, if the same guys that have it are running as much power as they are with no adverse effects directly related to this, you're good.
its mostly the slack in the inner cv's on the rear axles, and some from inside the trans itself.
some aftermarket axles can help, but they are quite quite pricey. supposedly strange has some new axles coming out that look beefy and nice and tight with some quality u-joints.
If people have positive results with them I'd consider it despite the price tag, eliminating the clunk would make the car so much more enjoyable to drive.
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1999 Rio Red SVT Cobra
-SOLD-
my 04 gt did it and my cobra does it. it must be a stang issue all together. just simple slack in drivetrain. but as stated b4, if guys pushing 700+ hp have had no probs...well maybe it just might stick together haha.
I've also heard the lubricant you use is an important factor as well - Trans and Diff. I was just going through my maintanence records and realized my clunk appreciably increased in frequency after getting my transmission fluid changed. Didn't really put the two together until today, so I'll probably move to some GM Synchromesh soon.
I honestly think it is normal. I also just bought a terminator (past November) and at first i thought i was doing something. But after reading of people having the same issue on this site i think it is normal. Check this out:
I was going to tighten my backlash to get rid of the clunk my buddy checked my backlash and it was in spec he then checked the trans and said most of the play was in the trans. I have noticed that during the warm months and after the trans and rear heat up the clunk goes away (mostly). I attribute this to everything expanding from heat and the tolerances get smaller so less clunk. This is in no way proven just what I have observed in my vehicle.
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Don't let your mouth write checks your car can't cash
Mods:
Billetflow 2.76 pulley, Stage 3 Steig ported blower, 60# injectors, GT pumps with wire upgrade, bazooka maf, stage 1 FPDM, full set of idlers,H&R race springs~MM IRS bushings,Diff bushings, Sway bar bushings JDM diff brace, global west full length subframe connectors, MGW shifter red handle~K&N CAI Magnaflow Cat-back and catted x-pipe
Black Chrome Saleen replicas 18x9 front 18x10 rear~Falken Azenis 615 275/35/18 and 315/30/18
i have found 3 things with mine that make a difference,as stupid as this sounds,,my air filter,,when its clean and car runs smooth no clunk,,shifting into 2nd first would make a difference also,,last i code code 455 and 457...car runs like crap when lite is lit..clear with predator and car purrs till cel is back on,,
My car clunks ever since I got the IRS swapped into it. I have the DSS level 5's with the upgraded inner CVs and Bruces bushing kit on the car. The whole diff was just rebuilt with a new differential, gears, bearings, seals, etc. The clunk still persists.
Now, we believe the clunk to be the rear differential mount bushing. Maybe I missed that one when installing Bruce's kit...I don't know...but I'm going to be trying another one of Bruce's bushings for $45 to see if it solves the problem (one of these days). If not, then I'll try the Billetflow IRS subframe mount pieces as that is another area that could possibly be causing the clunk (along with larger bolts).
____________________________________ '03 Azure Blue Mach 1Suspension, Tune, and Supercharger work by S&R Performance!
I wish I could quickly, permanently & cheaply fix my clunk too. Larger IRS subframe bolts, IRS subframe bushings, new diff mounts, FLSFC's, BF diff cover brace & still the cluck...
It's the Mustang clunk that's amplified by the Diff being bolted to the frame in the IRS. Billetflow IRS Brace and stiffer bushings may make the clunk worse - best advice is to get used to it. My 14mm bolts did nothing to the clunk, IRS brace did nothing to the clunk, MM Diff bushings did nothing to the clunk, but new transmission fluid and diff fluid made the clunk worse. It's in the drivetrain itself, somewhere...
i just bought an 04 cobra with 24k miles on it and it does it perdy loud, from what i hear they all have it, it bugged me at first but after hearing everyone has it, i got over it
My car clunks ever since I got the IRS swapped into it. I have the DSS level 5's with the upgraded inner CVs and Bruces bushing kit on the car. The whole diff was just rebuilt with a new differential, gears, bearings, seals, etc. The clunk still persists.
Now, we believe the clunk to be the rear differential mount bushing. Maybe I missed that one when installing Bruce's kit...I don't know...but I'm going to be trying another one of Bruce's bushings for $45 to see if it solves the problem (one of these days). If not, then I'll try the Billetflow IRS subframe mount pieces as that is another area that could possibly be causing the clunk (along with larger bolts).
i read on one of this sites that someone now is selling the rubber mounts less than before..when i was at ford finding them my first time they showed me that they have 2 different rear housing bushing,,, its a stock style but changes pinion angle,,,ford found a problem thier,,
I just bought a 04 with 56k miles still under factory warrantee.. after driving it I thought there was something wrong with it because of the clunk,spoke with two friends that also own cobras. They also said it was normal but it still bugged me, so being it still had warrantee I just took her in to get checked. They tore down the rear end and found that it needed ring and pinion in the rear.. ill update after I get the car back to see if that was the problem.
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