A question for all of you tribology PhDs

Falko

Falko

Well-Known Member
Joined
Mar 20, 2005
Location
Winston-Salem
So as I was replacing the steering box on my TJ yesterday, I got thinking about fluid selection.

I have been running ATF as my power steering fluid since I finished the Hemi swap, as that was the recommended fluid from the donor vehicle. Now I question which component should be used as the governor of fluid selection: pump or "motor"

I can only assume, having worked in a few different OEM facilities, that the Dodge system was engineered to use ATF to reduce the number of fluids in the factory and there may be no specific need to use this fluid...

I can also assume that the additive package in the ATF could have contributed to the demise of the sector shaft seal. If this is true, then the high detergent nature of the ATF most likely worked it's way through the deposits formed over the unknown mileage of the box, and that now that a reman is in place I should have no issue going forward.

What say you, internet experts?
 
It's all about the same on most PS systems. You could use hydraulic oil, power steering fluid (same as hydraulic oil), or atf. I don't think using atf would have deteriorated the seals, but it's possible. Just curious, why didn't you just put a sector seal in?
 
I've always read from places like PSC, etc. that ATF doesn't have the same lubricating properties as steering fluid and can lead to premature pump wear/failure. Can't add anything more to the topic.
 
a_kelley said:
It's all about the same on most PS systems. You could use hydraulic oil, power steering fluid (same as hydraulic oil), or atf. I don't think using atf would have deteriorated the seals, but it's possible. Just curious, why didn't you just put a sector seal in?
Click to expand...
My research suggested that the long term success of reseals are questionable, and that this box had 230k miles on it if it was original, and the front end was already completely disassembled which made it easy to R and R.
 
Only reasons to question the reseal would be gouged shaft or worn bearings. I've actually put undersize seals in tractor steering boxes on the input shaft with success. (Old 4410 with .060 deep groove on the diameter :eek:)
 
broncosbybart said:
I've always read from places like PSC, etc. that ATF doesn't have the same lubricating properties as steering fluid and can lead to premature pump wear/failure. Can't add anything more to the topic.
Click to expand...
I usually always run whatever the manufacturer calls for, be it PS, DM, Mercron.. As far as I knew PS fluid was a safe bet as long as it wasn't a Ford.
 
Falko said:
That was the original question... What specification do you follow: the pump or the drive?
Click to expand...
I would go with the pump specs, it generates the pressure and therefore is subject to faster wear with improper lube. Honestly, haven't seen many dodge/Jeep systems fail from using atf in place of PS fluid. @JodyTreadway
 
Def pump specs. Box don't care!

And if you have put a new pump on a 275k box...there is a high probability of a leak!

....keeping in mind, I'm not a tribology PhD, but I did stay at a Holiday Inn last night!:D
 
a_kelley said:
I would go with the pump specs, it generates the pressure and therefore is subject to faster wear with improper lube. Honestly, haven't seen many dodge/Jeep systems fail from using atf in place of PS fluid. @JodyTreadway
Click to expand...

Chrysler called for a change to ATF+4 to quieten down and prolong PS life on various applications during my time at the dealer. Minivans and JKs being the main ones.

Personally, I run hydraulic fluid in all of my rigs and have for years.
 
Back
Top