New Gen IV Owner

[ZZ SRT]

Hey guys!

I bought a 2008 Coupe a couple weeks ago and am loving it!

It's black with silver stripes, one owner, 2700 miles and came out of Weatherford, TX (near Dallas).

I live in Central Illinois so the driving season is wrapping up.

I have 1 thing that is hindering my enjoyment of the car and would like to get some feedback and make sure it is normal or that I shouldn't have it checked out by the dealer.

I have a pretty noticeable rear diff clunk during any sort of load reversal scenario.

The most noticeable times are if I dump the clutch at all (read: don't slip it very much) during upshifting. It also will do it upon downshifting if I don't rev-match well. I can also make it occur outside of shifting. Most commonly it will happen if I'm cruising in 5th gear at low RPM's (70 mph) and then blip the throttle. If I drive like a granny and slip the clutch a lot during every gear change, I can make it almost non-existent, but I hate slipping the clutch when going wide open throttle through the gears.

If I had to describe it, it feels like something is thudding against the floorboard off the car. Initially, it freaked me out, so I put the car on the lift, and checked every mount, nut and bolt to make sure nothing was loose or broken. Everything looks good. The only thing I found is that there is a larger amount of radial play on the driver's side output shaft of the rear diff.

Also, as a precaution, I bought 3 quarts of OEM rear diff fluid and friction modifier to change out the fluid, but I really don't think this is the issue seeing as the car has 2700 miles! Also, I would think if it were the fluid, it would be mostly during hard right turns, not when going in a straight line.

After doing a good deal of web searching, it seems this is a common problem on aggressive sports cars (such as on E46 M3's). Here is a TSB that BMW issued for a similar problem many of the M3's were having. I am slightly weary of this being "normal" because I have owned a couple BMW's in the past and they say everything is normal to keep down warranty costs

E46 M3 - "Clunk Noise" on Load Reversal MODEL
E46 M3 with S54 engine SITUATION
Customer may complain of a drivetrain rattle or knocking noise during a load change, e.g. 1st to 2nd gearshift at low engine speed, coming from the rear axle area. Further drivetrain checks reveal that the right side rear axle output flange appears to have more play (approximately 0.5mm to almost 1mm) when compared to the left side output flange. INFORMATION
The radial play on the right side rear axle flange is a normal design characteristic of the new M differential lock style rear axle used on E46 M3 models. Therefore an M3 differential should not be replaced due to a difference in play (when comparing left to right side differential output flange play) since this will not eliminate a drivetrain rattle or knocking noise. IMPORTANT
In order to transmit engine torque to the rear wheels instantaneously, without any time lag, the whole M3 power train was designed with maximum torsional rigidity. Consequently, the flywheel mass and its damping capability has been reduced to a minimum. As a result, during an abrupt torque transfer (e.g. 1st to 2nd gearshift at low engine speeds) driver receives an acoustic feedback, which can be interpreted as a "clunking or rattling" noise. This characteristic is common in many high performance vehicles. Activation of the "Sport Mode" offers an additional increase in driving dynamics. As a result, acoustic feedback from the power train may be even more pronounced. The acoustic feedback characteristic is not a symptom of a failure, and does not compromise long-term reliability of drivetrain components (clutch, transmission, differential), nor does it adversely affect performance of the vehicle. WARRANTY INFORMATION
For information only.

Anyways,

Anyone else experiencing this with the Gen IV diff? Kind of irritating paying the extra money for the upgraded Gen IV driveline and then have issues with 2700 miles!

Thanks for your time guys!

 

[ohlarikd]

They all clunk. Mine (05) clunks with 860 miles on it. Appears to be perfectly normal and expected. However, let the experts chime in...

 

[01sapphirebob]

Drive line clunk and it happens on all Model year vipers so you should be ok.

 

[BlknBlu]

Welcome to the VCA. That is the nature of a Tremec 6 spd tran. Also the Gen IV cars are the first with Drive by wire technology and with each year it has improved. The Mopar Controller will correct that issue.

Enjoy and Drive safe

Bruce

 

[Torquemonster06]

Welcome to the VCA. Enjoy your new ride.

 

[ZZ SRT]

Thanks guys!

Now I can drive it a little harder without worrying about breaking something!

It took over 2 weeks for my account to be "activated" on here (just happened this morning).

Any reason why I still am not allowed to view the "Illustrated Upgrades"????? Do I have to be a paying VCA member to view?

 

[Steve M]

Any reason why I still am not allowed to view the "Illustrated Upgrades"????? Do I have to be a paying VCA member to view?

Yes, you have to be a VCA member to view that section.

 

[DrTaco]

Welcome to the forums and congrats on the car!

 

[HyperViper]

Your explanation sounds a little extreme to me. While I do get some of what you are describing, it is every once in a while occurrence.

 

[Allan]

With the Viper, some driveline 'lack of refinement' is normal. .............a bigger concern will be the cops.

 

[HobokenViper]

Congrats. On the new Viper! Black/silver is an awesome color combo! I also just got my 2008 blue/silver vert maybe 2 months ago and couldn't love it more, but also notice that same clunk you talk about and mine had only 1,900 miles on it when I picked it up. Unfortunately I think it's normal.

Well, that clunk may be the least of my issues as I had to evacuate my town because of hurricane Sandy today and had to leave my new Viper back home in my garage on the 3rd floor of my building. Hopefully my car and apartment are both still in one piece when I get back.....

 

[Slithr]

Your explanation sounds a little extreme to me. While I do get some of what you are describing, it is every once in a while occurrence.

^^^ This .... I've maybe heard a clunk 3 times in 2+ years of ownership, and I've put 12k miles on the clock. I'd be concerned if I heard a clunk as often as you describe.

 

[ZZ SRT]

^^^ This .... I've maybe heard a clunk 3 times in 2+ years of ownership, and I've put 12k miles on the clock. I'd be concerned if I heard a clunk as often as you describe.

After hearing people's opinions, I've determined my clunk is normal. It only happens if I drop the clutch at low RPM shifts. If i shift about 3k it doesn't occur. The best example would be if I am cruising at 2500 rpm in 2nd gear and then decide to shift into 3rd to cruise at low RPM. It would clunk because I'm not trying to accelerate, but simply maintain my speed while shifting into a higher gear.

The more I have driven the car, I have learned to stay in the powerband (after all, these cars aren't practical so who cares about fuel economy).

I went on a pretty brisk drive last night in Mexico and didn't have any clunk occurrences under heavy load or upshifting.

I'm also learning all the nuances of these cars which seem odd at first. For instance, in cold weather, until the car gets up to temp, the TR6060 seems to nibble going into 2nd and 3rd. I've researched this as well and apparently it's common because of the tight tolerances of the brass blocker rings.

I guess I'll just drive it and assume all is normal until something breaks, then upgrade!

 

[Slithr]

It sounds like you've done your homework, and come to think of it, everytime I've heard it it has been low RPM ..... and like you say, not the way they're meant to be driven. Glad you're getting used to the beast, and its nice to be that close to Mexico for some testing.

 

[ZZ SRT]

Well I gave in and joined the VCA.

Looking forward to hitting up some Illinois meets next summer!