Question: Differential fluid in the morning

[Viperfreak2]

I've noticed since the weather has turned cold, that the car is making some grumbly noises when backing out of the driveway at an angle. It does it again at the end of the street making a 90 degree turn. Only when cold. One other symptom: One wheel spins (yes one) as I let off the clutch. I'm sure it's the outside tire (right at the driveway, left at the end of the street) I feel like there's nothing 'wrong' with the car, just maybe the viscosity of the differential fluid isn't allowing the torque sensing function of the rear end to work correctly. Within a mile everything is normal, although I can't say enough bad things about the run-craps when cold. Dangerous.

 

[Y2K10 SRT#39]

Can you tell us whet temperature you consider cold?
I find no problems at 40 degrees here in WA.
PBR

 

[Skip White]

The diff. fluid in the SRT should be around 80-140w Don't even think of going to 75-90w I'm sure they have put a synthetic fluid in these from the factory. I would usefAmsoil Series 2000 80-140w this has a pour point of -50F I doubt the type thats in there has that, and as you know these cars have a very unusual setup in them, and a very good one. If it were not for this setup the car would have very poor traction period, due to the tires on the car. I guess this may also be the nature of this setup also. Positract's also act a little funny when cold.

Skip White

 

[Tom Sessions]

The rear diff in the new viper is similar to the diff in a Grand Cherokee with quadra-drive.It has what they call a vari-lok axle which has a pump in the diff that must pump up first to lock the axles together.It does this by one wheel spinning faster than the other which activates the pump to lock the axle.Once it pumps up there is minimal slippage.As for the noise this axle does take the same additive as the old axle for the limited slip.If it does ot have enough it will make a odd growning noise while turning.The factory fill fluid is 75w140 syn.

 

[Skip White]

Tom is correct about the diff design. It is the greatest thing theve done to the car. I don't think you need a friction aditive, as this diff has no clutches in it, and that is the purpose of the additive. I'm sure what you are hearing is due to the cold. Never get on it when cold. Some people will warm the engine up real good, and then they forget about the trans and especially the diff. I'ts death on the diff to punch it when it's very cold out. The oil pressure in the diff would be tremendous when very cold out. A few miles 5-10 would probably warm it up enough to be safe.

Skip White

 

[Tom Sessions]

This diff does use a clutch pack similar to the one in a limited slip unit.Chrysler calls this a HYDRA-LOK diff instead of the VARI-LOK as in the Jeep.If you don't use the additive the rear end it will let you very quickly.

 

[Viperfreak2]

In SC, 20 degrees is considered cold. It was about that temp this morning, Viper left outside. I know, I should have pulled it in, but got lazy and fell asleep during Average Joe Hawaii. Same issue this morning: Grumbling on sharp turns, wheel spin at all slow corners. Goes away very quick. You'd think they would have noticed this in icy Detroit during cold weather testing last winter and included a blurb in the manual as 'normal'.