Transmission and/or Rear Differential Problem

[RyanRC187]

Unfortunately it looks like I've come upon my first problem as a 2003 Viper SRT-10 owner. Any help or guidance would be much appreciated, and I've conducted searches with little results.

For the past month or so I was noticing that my car would making a "clicking" or "clunking" sound in slow (approximately 5-10mph) sharp turns, such as U-turns and driving in parking garages. Other than the noise, I've not experienced any other problems, but I wanted to get it checked out. I've read similar account of other cars needing their differential fluid replaced, which has oftentimes solved the problem. This morning I dropped the car off at the local Dodge dealer that has one certified Viper tech and told him off the issues.

I just got a call about an hour ago saying that he thinks the entire transmission or differential needs replaced, and then quoted me the outrageous prices of $5,300 for a new transmission, or $3,350 for a new rear end. Obviously those prices are completely ridiculous. And just now as I'm typing this I received a call from the representative that stated the tech wants to "put in a new transmission assembly and drive it to see if that fixes the problem."

Now I've told her to have him replace the fluid in the differential and I'll be coming to pick up the car. But I have a few questions.

1) Any good shops in the Virginia Beach area that may be of more help if replacing the fluid doesn't solve the problem.
2) What type of cost would I be looking at if I do need to replace the transmission? The differential?
3) Best sources to purchases these parts if it does come to that?

Thank you guys very much.

 

[Sonoman]

The fact that it happens in sharp turns points strongly to the rear end, since sharp turns is where the differential action between the two wheels occurs (one turning slowly through a small radius and the outer turning more rapidly through a large radius). However, some clunking is normal for limited slip rear ends when the fluid is low, the friction modifier is in need of replacement, or the differential has new friction discs. Imagine a clutch engaging in the differential every time one wheel has significantly faster rotation (ideally, "spin", but tight cornering simulates this action). The purpose of the friction modifier additive is to reduce the clutch friction slightly so that when engagement does occur it is smoother and less grabby, otherwise the clunky differential action will be noticeable by the driver. In race vehicles this is largely ignored, but for the street, it is a quality of ride issue.

How the transmission would clunk only in tight turns is a mystery, since it is not really affected by whether the car is turning or not.

I think changing out the diff fluid and adding a new 4 ounce bottle of Mopar friction modifier is a good start. If that doesn't fix it:

Unitrax in CA will sell you a beautifully rebuilt Viper differential for half the amount you were quoted, including a new gear set in your choice of ratios. You can even upgrade to a Gen IV diff if desired. Call Jon at PartsRack for prices-- he has an arrangement with Unitrax to supply them with Viper cores and handle the transactions.

BTW, "clicking" sounds from the rear typically originate from bad CV joints, such as those in the half-shafts of your Viper. A good ear can tell bad CV joints from a differential problem. Make sure you don't have a bad CV joint before doing work on a rear end. Labor to pull out the diff and replace it is significant, in addition to the cost of the part itself.

 

[RyanRC187]

Sonoman,

Thank you for your quick reply. I'm hoping that a change in the fluid, along with the addition of Mopar friction modifier will take care of the problem. I thought that was the most likely culprit after the research I had done. I'll update the post after I pick up the car and let you know if that was ultimately the solution. If not, I very well may be giving Jon a call.

Thanks again.

 

[Steve-Indy]

I would only let that shop change the diff fluid after I noted the part numbers on the 2 fluids and while I watched the job...since their "diagnostic abilities vs. greed ratio" are unknown to us forum readers. Of course, they may be straight shooters, but it does sound a little strange in my opinion. There are shops that can make your T-56 a much better transmission for half of the quoted tranny price alone. Good luck!!

P.S. Anyone check torque on hub nuts, or consider bearings??

 

[MVP auto]

I suggest you also check the rear axle nuts for proper torque. They will make a "click" noise on a turn. Also may sound as a "crack" sound.
I would not reccomend a transmission on the suggestion of "I think thats what it is" ???

 

[Sonoman]

I would only let that shop change the diff fluid after I noted the part numbers on the 2 fluids and while I watched the job...since their "diagnostic abilities vs. greed ratio" are unknown to us forum readers. Of course, they may be straight shooters, but it does sound a little strange in my opinion. There are shops that can make your T-56 a much better transmission for half of the quoted tranny price alone. Good luck!!

Good point. The dealer was awfully quick to recommend complete replacement of expensive assemblies. Of course, if it was under warranty, they would say "all is normal" and "don't worry about it, they all do that"! ; -)
I suppose dollar signs light up in the eyes of some non-trustworthy repair shops if a car like the Viper shows up. Makes it tough to be a car owner if you don't do your own work or have mechanics you can trust.

 

[Venomiss]

Why not ask the experts directly on your question-the SRT Engineers Live Chat that is taking place today June 21st, 2011 at 4:00 Eastern time.

 

[RyanRC187]

Why not ask the experts directly on your question-the SRT Engineers Live Chat that is taking place today June 21st, 2011 at 4:00 Eastern time.

Thank you - Posting in there now.

So as I requested, the differential received new fluid and Mopar friction modifier. The tech had me come into the back while the car was in the air with the windage tray remove. He said that there was "excessive backlash" in the tailshaft of the transmission. Now I don't know what "excessive" is exactly, but I was able to move the driveshaft up and down approximately 1 millimeter, or less. There certainly was some movement; is that normal or should there be absolutely none at all? Regardless, I advised him to go ahead and put her back together and if the problem wasn't solve then I'd look for a new solution.

Unfortunately the problem isn't solved. Driving in a parking garage after receiving the car from the service department I've noticed that the car only makes the clunking sound when the transmission is in gear and the clutch is not depressed. During the same slow turns, with the clutch depressed, the car makes no noise.

 

[RyanRC187]

Well, after two days and about 100 miles on her, the noise has stopped. Like the SRT Engineers suggested, the friction modifier needed some time to adhere to the parts of the differential. I'm glad that I researched the problem beforehand and a big thanks to all of you guys. I definitely won't be returning to Hall Dodge in Virginia Beach.

 

[Sonoman]

Well, after two days and about 100 miles on her, the noise has stopped. Like the SRT Engineers suggested, the friction modifier needed some time to adhere to the parts of the differential. I'm glad that I researched the problem beforehand and a big thanks to all of you guys. I definitely won't be returning to Hall Dodge in Virginia Beach.

Congrats on the cheap fix! Now you have more money for the fun Viper mods. ;- ) Mine behaved similarly with a freshly rebuilt rear-end and new gears... when I first backed her out of the driveway, you should have heard the clunking! The sounds from the clutch discs gradually went away and took more extremely tight turns to instigate a clunk. Unitrax stated that the break-in period for the rear end was about 500 miles, with the first three heat cycles somewhat critical, but they were mainly referring to the ring and pinion set more so than the limited slip clutch material. So it appears that the friction modifier is a little on the slow-acting side in some cases? What does the factory do to keep brand new vehicles from havng noisy diff clutches driving off the dealer's lot? Pre-soaked friction discs?