What does it do when you launch straight?

 

Under a straight launch it is still spinning both tires.

A locker should not slip as you turn and hit the gas.. It will disengage and free spool wo tension to eliminate wheel hop when turning but soon as throttle is applied it instantly locks up.. But not important as we have lsd...

Lsd can be temperamental.. When one things of say "posi" (both tires spinning together that's not actually what an lsd does or is supposed to do.. Now when over powered with loss of traction most times both wheels spin.. The reason is the friction modifier can't respond fast enough.. What tech is happening in this case is one wheel is spinning and power being transferred to the other then back and forth over and over.. It happens so fast the end result is two strips.. But this is not how an lad is designed..

Lsd is not much more then an open dif with a friction disc.. When slippage occurs this causes friction on the disc when makes it transfer power to the other wheel in an attempt to remove power from the slipping wheel and get traction.. To create the proper friction and transfer.. A special lubricant I
With additive is needed.. If you put regular fluid in an lsd what you are left with is essentially a normal open diff cause there is no friction.. This is very common in 4wd vehicles that are street driven even with the right fluids.. A lot of people use lsd in front axels on 4wds so they can turn on the street wo breaking axels and CV's.. Wheel wheeling you apply slight amount of break pressure and this makes the front mounted lsd act more like a front locker always turning both wheels... The same can apply to a rear lsd.. It's very possible to need slight break pressure at times to help the friction disc work properly.. (Little off topic but thought it would help explain how it works a little better and most of my automotive XP is in the 4wd world too)

In a rwd only car what is happening is neither tire has traction so it moves power back and forth so fast that is acts as though both wheels are being powered at same time but reality is its not.. Very slight break pressure will emilinate this.. Not enough to stop the car and fully engage pads per say.. But just enough basically to engage brake lights.. But this shouldn't be needed often.. Should be a rare occurrence... You should try straight line launch wo braking at all.. See what happens.. Then try larger more sweeping turns.. Then try sharp abrupt turns.. Also try power breaking.. See if it's consistent this will help determine if it's mechanical or if it's something you are asking it to do that it's not mention to do.. Could be anything from tire pressure issues to suspension.. Etc.. If you unload the rear abrupt enough an lsd can not kick in and do what it's supposed to..

My Intial thought is that you need a fluid change with new additive.. Did you get your diff fluid changed recently? If so that's the simple answer.. They gave you the wrong fluid that doesn't have the additive in it meant for a regular open diff.. If you are driving like a teen 24/7 it's possible (but unlikely) you burnt the fluid just enough that it's not doing its job.. Just need a change in dif fluid.. This happens with cheap fluids.. Or bad runs.. If you keep getting peg legs... Especially on a straight launch have the fluid flushed and changed ASAP.. A sign that the fluid isn't up to par can be a lot of wheel hop to. Of you get wheel,hop on the street then something is amiss. Don't know what brand lsd fac is using but some can burn up if the mix isn't right.. Could be as simple as the fluid being cold though as well.. Many variables with an lsd I prefer lockers and spools for the rear long as the wheelbase is long enough to not break things when turning..

Personally I'd change the fluid myself and look for flakes in the fluid.. Could be just a bad lsd and if so you're gonna have some small particles in the drained fluid.. A magnetic drain pain will show this quickly even to an untrained eye.. Trying to see small metal flakes in hydrolic fluid isn't easy..

If you take it to dodge they will likely change the fluid look for metal and if none send you on your way.. But I for one like to know for myself so I'd do it myself for piece of mind.. If you do and find metal flakes.. Safe them and take them to the dealer with you so they know to replace the lsd and not just change the fluid again..

I guess the fact that this is a lsd and not a locker is probably the entire issue here, because i must have hit the gas at just the right moment when the rear was unloaded that it lit up the inside tire and the friction discs couldn't catch up to engage the outside tire. The car only has 2000 miles on it and still on the factory fluid so I would hope that isn't my issue. I guess i'm just used to a locking rear in my GMC truck and my old Z06. I will have to get better at drifting and start the tires spinning before i initiate my turns, it just really surprises me that Dodge would even allow a 707hp muscle car to ever spin only 1 tire. I hate 1 wheel peels with a passion, they are just so lame.

...take it out of Sport if you do this.....Sport still has stability controls.

Set your car to sport then push and hold the button to remove traction completely.

As of now I am the only one who I know of that has blown out the rear.

This unit ( according to tech, I have not been inside one) is clutch style and they have had varying quality on the clutch pack assembly.

From what I felt and the sounds it made before and after replacement I can say the car felt weak and would chatter under acceleration before and sooooo smooth and strong after ( until wheel hop) which is a whole other gripe.

But put the car on a 2 post and rotate a rear tire, have someone on the other side feel the engagement of the opposite side. ANY slack, bumping or non engagement .......replace the rear under wrty.

make sure the parts dept lists your part order as VOR ( vehicle off road)....parts will arrive in a week or less and the rear takes less than an hour to replace.

I know Sport mode still has stability controls, i'm not a pro drifter and want the stability control to kick in if I get a little too crazy. Competitive driving mode in my old Z06 still had the stability control without traction control and this was a perfect setting to let you get a little sideways, but it would always real you back in if your drift angle went too far.

Thanks for all of the information guys!

 

something is not right

 

It can happen, it did on Linda's Charger once and I thought the same thing, it's a limited slip unit.
TC

 

I agree with TC... if you go around a corner with a limit slip or in a locker... it either unlocks or slips as you turn. If you jump on it while this is happening it can light up one wheel. That is why I was asking what it does when you attempt a straight launch.

 

A locker should not slip as you turn and hit the gas.. It will disengage and free spool wo tension to eliminate wheel hop when turning but soon as throttle is applied it instantly locks up.. But not important as we have lsd...

Lsd can be temperamental.. When one things of say "posi" (both tires spinning together that's not actually what an lsd does or is supposed to do.. Now when over powered with loss of traction most times both wheels spin.. The reason is the friction modifier can't respond fast enough.. What tech is happening in this case is one wheel is spinning and power being transferred to the other then back and forth over and over.. It happens so fast the end result is two strips.. But this is not how an lad is designed..

Lsd is not much more then an open dif with a friction disc.. When slippage occurs this causes friction on the disc when makes it transfer power to the other wheel in an attempt to remove power from the slipping wheel and get traction.. To create the proper friction and transfer.. A special lubricant I
With additive is needed.. If you put regular fluid in an lsd what you are left with is essentially a normal open diff cause there is no friction.. This is very common in 4wd vehicles that are street driven even with the right fluids.. A lot of people use lsd in front axels on 4wds so they can turn on the street wo breaking axels and CV's.. Wheel wheeling you apply slight amount of break pressure and this makes the front mounted lsd act more like a front locker always turning both wheels... The same can apply to a rear lsd.. It's very possible to need slight break pressure at times to help the friction disc work properly.. (Little off topic but thought it would help explain how it works a little better and most of my automotive XP is in the 4wd world too)

In a rwd only car what is happening is neither tire has traction so it moves power back and forth so fast that is acts as though both wheels are being powered at same time but reality is its not.. Very slight break pressure will emilinate this.. Not enough to stop the car and fully engage pads per say.. But just enough basically to engage brake lights.. But this shouldn't be needed often.. Should be a rare occurrence... You should try straight line launch wo braking at all.. See what happens.. Then try larger more sweeping turns.. Then try sharp abrupt turns.. Also try power breaking.. See if it's consistent this will help determine if it's mechanical or if it's something you are asking it to do that it's not mention to do.. Could be anything from tire pressure issues to suspension.. Etc.. If you unload the rear abrupt enough an lsd can not kick in and do what it's supposed to..

My Intial thought is that you need a fluid change with new additive.. Did you get your diff fluid changed recently? If so that's the simple answer.. They gave you the wrong fluid that doesn't have the additive in it meant for a regular open diff.. If you are driving like a teen 24/7 it's possible (but unlikely) you burnt the fluid just enough that it's not doing its job.. Just need a change in dif fluid.. This happens with cheap fluids.. Or bad runs.. If you keep getting peg legs... Especially on a straight launch have the fluid flushed and changed ASAP.. A sign that the fluid isn't up to par can be a lot of wheel hop to. Of you get wheel,hop on the street then something is amiss. Don't know what brand lsd fac is using but some can burn up if the mix isn't right.. Could be as simple as the fluid being cold though as well.. Many variables with an lsd I prefer lockers and spools for the rear long as the wheelbase is long enough to not break things when turning..

Personally I'd change the fluid myself and look for flakes in the fluid.. Could be just a bad lsd and if so you're gonna have some small particles in the drained fluid.. A magnetic drain pain will show this quickly even to an untrained eye.. Trying to see small metal flakes in hydrolic fluid isn't easy..

If you take it to dodge they will likely change the fluid look for metal and if none send you on your way.. But I for one like to know for myself so I'd do it myself for piece of mind.. If you do and find metal flakes.. Safe them and take them to the dealer with you so they know to replace the lsd and not just change the fluid again..

 

When will eaton Detroit make a locker or true trac and a way to have bolt on gears?

 

Eaton TT are just lsd units.. I wouldn't be surprised to learn that the factory cat lsd is made by them.. I know they make all the factory GM truck lockers and a lot of other car brand lsd units.. As for mass produced units for a semengliy low production car dont hold your breath.. I don't see anyone investing the funds to make a product for our cars with such a one off assembly... Funny thing is our rears are actually just a modern version of a ford 9" although metric lol.. But far as aftermarket support.. I don't see it coming.. Better Swapping to more common system and going that route.. And no matter the tech of today.. Nothing beats the old school 9" still.

But in truth it's all just metal... Not anything any decent computerized matching shop can't fab a 1 off of fairly easy.. But then lays the cost... You could weld things together and make a country boy spool for free.. But then you're gonna need some spare axles...

Best hope would be that a major aftermarket company is behind the production of that factory unit.. Then they would already have everything they need to make other units just a matter of some demand to justify them retooling a few machines for a couple days...

 

I was thinking the hellcat diff is a clutch type posi, imho the tru trac helical type would be a step up.

 

I didn't think about that.. But I'm sure you are right it's clutch type. All factory units usually are.. But even the helical lsd like the true trak has issues too. No lsd is perfect.. Reason why most race vehicles or off road vehicles run lockers or spools.. Even Detroit lockers I've had numerous issues with.. Not sure why butwhen run hard the damn bolts in the case like to back out.. I'll take a full spool any day but that requires some big money in a beefy axle so you're not replacing shafts everyday.

 

...take it out of Sport if you do this.....Sport still has stability controls.

Set your car to sport then push and hold the button to remove traction completely.

As of now I am the only one who I know of that has blown out the rear.

This unit ( according to tech, I have not been inside one) is clutch style and they have had varying quality on the clutch pack assembly.

From what I felt and the sounds it made before and after replacement I can say the car felt weak and would chatter under acceleration before and sooooo smooth and strong after ( until wheel hop) which is a whole other gripe.

But put the car on a 2 post and rotate a rear tire, have someone on the other side feel the engagement of the opposite side. ANY slack, bumping or non engagement .......replace the rear under wrty.

make sure the parts dept lists your part order as VOR ( vehicle off road)....parts will arrive in a week or less and the rear takes less than an hour to replace.

 

...take it out of Sport if you do this.....Sport still has stability controls.

Set your car to sport then push and hold the button to remove traction completely.

As of now I am the only one who I know of that has blown out the rear.

This unit ( according to tech, I have not been inside one) is clutch style and they have had varying quality on the clutch pack assembly.

From what I felt and the sounds it made before and after replacement I can say the car felt weak and would chatter under acceleration before and sooooo smooth and strong after ( until wheel hop) which is a whole other gripe.

But put the car on a 2 post and rotate a rear tire, have someone on the other side feel the engagement of the opposite side. ANY slack, bumping or non engagement .......replace the rear under wrty.

make sure the parts dept lists your part order as VOR ( vehicle off road)....parts will arrive in a week or less and the rear takes less than an hour to replace.

The traction control should actually help the lsd since it works by brake control which would aid the friction disc.. I'm just personally not a fan of lsd period. It's one of those too many moving parts to be effective things for me.. Only time I've used them on builds are for the front axle on jeeps for daily drive weekend warriors do to the short wheelbase.

 

If you were in sport mode that could be your issue.. As you cut the wheel to unload the suspension and hit the gas not only are you quickly shifting weight and possibly having issue with the lsd building friction but now you are engaging the stability control which will modulate control of the brakes to try and keep you straight.. This could've caused a nose dive while transitioning wieght to the outside wheel causing even more of a sudden imbalance and preventing the lsd from working.. Lsd is designed to transfer traction as needed but when you have a complete loss of traction suddenly.. (Like one wheel completely off the ground or close to it) it will act like an open diff... This could very well explain what you experienced.. Personally I'd still change the fluid.. But if straight line launches are ok then I'd say it's not a major mechanical issue and all is ok.. What was the settings for the suspension? Try track mode for that to stiffen things up and you will likely be able to keep doing this exactly as you are used to and comfortable... A stiffer setup will make for more predictable drifts anyways allowing you to control through throttle inputs..

FYI.. Drifting is an entirely different animal in itself.. Against all instinct if you begin to lose control you give more throttle not less and especially never lifting entirely.. This will upset the cars balance and send you into a spin every time.. To get straight and under control you actually give more throttle and more wheel spin odd as it may sound..

One more thing to add.. The challenger wheelbase is a tad short.. This will make for faster snap backs and loss of control.. The Chargers are better suited for this as they have a longer wheelbase.. So as you increase throttle to gain traction you also need to start using less cross steer so when it does gain traction it doesn't send you into an opposite lock spin..

 

Are any of you guys getting any wheel hop when use the launch control?
If i set mine 4500 and turn loose it will,spin the tires about 3 ft and then start to wheel hop. It leaves black rubber for about 10 ft with foot long gaps in bwtween the marks. It aslo does the same thing when you shift and spin the tires. It jumps all over the road. Anymthoughts on this?

 

it was like a can of ball bearings when it was out of the car.......took 1800 miles of abuse tho........

I recently tore the center bearing due to wheel hop......3rd gear when it hopped ( it broke loose earlier than usual, and I could'nt get out of the gas fast enough) now there is a clunky clunk in the center tunnel when it shutters a bit when shifting or turning and giving throttle........

sure is a pain in the ass with this stuff, especially if you are trying your best to stay absolutely stock.

 

Dynatrac Pro 60 IRS center section.


Installing Dynatrac's Dana 60 Differential and Axles - Mopar Muscle

 

Mine does this as well so im very inteested as if this is common or if there is something not right

 

Did it again twice yesterday, inside tire just instantly up in smoke. Does everyone only drive these cars in a straight line to not see this major issue. I think i would go through an entire set of tires in one autocross run just from blowing off the inside tire in every turn. Very disappointing.

 

I bought one just to go straight line fast.

 

Rear is bad....warranty. talked to my SRT tech and under throttle both should grab.

Ps I am on my 3rd.
Yes 3rd. Rear assy. Their supplier is not good, if it was out of warranty

 

Rear is bad....warranty. talked to my SRT tech and under throttle both should grab.

Ps I am on my 3rd.
Yes 3rd. Rear assy. Their supplier is not good, if it was out of warranty

Are you agreeing with me and saying my rear is bad?

 

If it was out of warranty I would build it right myself....

 

Dynatrac Pro 60 IRS center section.


Installing Dynatrac's Dana 60 Differential and Axles - Mopar Muscle

I like it, they seem to have a cure for most of our problems. I am surprised they do not mention or recommend new cradle bushings. Some of us believe they are responsible for moving around dramatically causing things from wheel hop to potential drive shaft failures.

 

If i sense a problem with my hellcat or any of my cars in general

1. see if anyone has the same problem online and if so, what the fix was
2. if nothing online, bring to dealer
3. if dealer can't figure it out, make post online asking other users to try and get an answer.

If you think your rear diff is acting up (It sounds like it is but also that stability control was attempting to keep you straight), then you need to bring to the dealer. Just remember they won't test it via doing a sideways drift out of an intersection or parking lot into the street.

 

Exactly what i am worried about, how are they going to replicate to even know if there is a problem?

 

They'll do what they did like my exhaust. Start it up, give it a few rev's in the lot or lift it in the service bay. If it makes no bad sounds and ain't leaking they throw it back onto the lot and tell you to pick it up.

Maybe they'll do a test drive and try to replicate it, most likely not. What you do then is ask a tech to sit in the car with you and show them it locking up when it shouldn't (Aka scare the shit out of him). Then they order the part. That's how i got my exhaust replaced.

 

I don't think stability control has anything to do with differential operation, it's all brake modulation.

 

If the clutch plates have been glazed too badly or abuse too badly because of one tire spinning the plates must be replaced to work appropriately again just like a standard transmission clutch

 

Unfortunately with the asinine welded gear construction of the hellcat differential not accepting any aftermarket carrier units we are left with only one option and that is to replace the entire differential assembly with a factory new unit and we only have four total gear choices

 

The Ford 9 inch or Dana 60 conversion is quite expensive and a huge leap from stock, hopefully the aftermarket will come to the rescue with true track or wave lock or Detroit locker type carrier units for the stock hellcat differential assembly and open the door for gear ratio choices

 

I personally feel that a true track helical gear diff or Moser wave lock would be the ideal differential for the hellcat.
our stock posi clutch plate type unit is ancient technology and the softest traction device available.
I would love to drive a manual hellcat with a Detroit locker once or twice just for fun but I think it would be too dangerous for the street or a road course. Fixed parameter straight line drag race types could use it however.

 

So how do I open up a case with SRT about this? Or should I just call the dealer and see what they say?

 

So you bought a 4400 lb. car to drift???????? WTF?? Sell it and get yourself a Mazda Miata. Then you can complain on their forum that it doesn't have enough power.