1977 Chrysler New Yorker Differential fluid

[Nick C]

I'm changing the Differential fluid on my 1977 NYB. It is equipped with a 440 and has a 12 bolt cover. I wondering if it needs a friction additive. Also, I do not see any spider gears inside. Instead there are some springs. What type of differential did they use on the NYB?

 

[Davea Lux]

I'm changing the Differential fluid on my 1977 NYB. It is equipped with a 440 and has a 12 bolt cover. I wondering if it needs a friction additive. Also, I do not see any spider gears inside. Instead there are some springs. What type of differential did they use on the NYB?

If you see springs, it is a sure grip. Verify by turning one wheel, the other should turn the same direction. The Mopar additive was part number 4318060. The '60-'70's stuff was made from whale oil and that is no longer available. Mopar updated the formula with the same part number. Lucas oil 85-90w HP gear oil is another alternative that is suitable for the sure grip unit. Be careful about using synthetic oils as they are not all created equal. The NYB used a 9.25" rear end and the cover has twelve bolts and looks like a stop sign.

Dave

 

[Nick C]

If you see springs, it is a sure grip. Verify by turning one wheel, the other should turn the same direction. The Mopar additive was part number 4318060. The '60-'70's stuff was made from whale oil and that is no longer available. Mopar updated the formula with the same part number. Lucas oil 85-90w HP gear oil is another alternative that is suitable for the sure grip unit. Be careful about using synthetic oils as they are not all created equal. The NYB used a 9.25" rear end and the cover has twelve bolts and looks like a stop sign.

Dave

Thank you Dave. I appreciate your help. Yes both wheels turn in the same direction. If I use the Lucas product will I still need an additive? Also, before listing this post I used Valvoline HP 80-90. It doesn't say if it is Synthetic but is does say that it is API GL 4-5 suitable for conventional and limited slip. Will this also be a suitable oil?

 

[Davea Lux]

Thank you Dave. I appreciate your help. Yes both wheels turn in the same direction. If I use the Lucas product will I still need an additive? Also, before listing this post I used Valvoline HP 80-90. It doesn't say if it is Synthetic but is does say that it is API GL 4-5 suitable for conventional and limited slip. Will this also be a suitable oil?

Either should work and you will probably not need an additive as both are suitable for limited slip units as is. If the unit chatters go ahead and put in the additive, otherwise it should be good to go.

Dave

 

[Nick C]

Either should work and you will probably not need an additive as both are suitable for limited slip units as is. If the unit chatters go ahead and put in the additive, otherwise it should be good to go.

Dave

Thank you again Dave. The read end had some clanking shifting from drive to reverse. The old fluid looked like complete sludge Hope the sound will be reduced with the new fluid change.

Thank you again for your help.

Best Regards',
Nick.

 

[Davea Lux]

Clanking is usually the result of excessive gear lash, but try changing the fluid. Gear lash is annoying but the only way usually to get rid of it is to rebuild the rear end. As long as the unit is not howling or making other obscene noises, drive like it is.

Dave

 

[75LandYacht]

Clanking is usually the result of excessive gear lash, but try changing the fluid. Gear lash is annoying but the only way usually to get rid of it is to rebuild the rear end. As long as the unit is not howling or making other obscene noises, drive like it is.

Dave

Agreed Dave , Im having to rebuild the Axel in my 77. excessive noises and the backlash is LOUD. SO Mr Nick C^^ if Ain't broke!! Don't fix it.....

 

[volksworld]

the clank could also be a bad u joint