need info on posi's and gears... - PowerStrokeNation : Ford Powerstroke Diesel Forum
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post #1 of 18 (permalink) Old 04-24-2008, 10:18 AM Thread Starter
 
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need info on posi's and gears...

please post your opinions/experiences with posi units for the ford 10.5" rear end.
i am not exactly sure the difference between the auburn, eaton, and detroit brand posi units other than the type of units that they are..

but i would appreciate some input from you guys on the strengths/weaknesses of the different types, and the reasons why you would go with one over the other please.

my goals for the vehicle are heavy street/strip action, aggressive off roading (but no rock crawling, and no towing )

these are the 3 main units i have been trying to decide between, if there is something else out there that i have missed, please feel free to give your 2cents on those also:

AUBURN LTD SLIP : preloaded cone style clutch system. hardened spider
gears. this appears to be the most expensive type of the ones i've
been looking at. If i were to go with a clutch type posi, this is the
one i've been leaning toward, but i'd like to know real world difference
between this type of clutch and the eaton posi.

EATON POSI : carbon fiber clutches, forged gears, rebuildable. preload
springs with clutches. this appears to be about 100 bucks cheaper
than the auburn unit, is this type less reliable ? or just cheaper to
manufacture ?

DETROIT TRUE TRAC : clutchless posi unit. price was not the determining
factor when i found myself wanting to go with this type of posi over
the overs, even though it is actually quite a bit cheaper than the
clutch style posi units. I may be dead wrong, but i just figured that
a gear drive posi unit would seem to last longer than a clutch type
before needed to be rebuilt/replaced ??

fill me in guys, so that i can make an informed decision, and i am wanting to do this immediately. my truck should be back from the tranny shop this afternoon and i want to get the 4.10/4.11's on as soon as possible.

and before you add them to the list, no i don't want to run a "locker"
i know all about the air locker, the ratcheting locker, and the electronic locker, i just want a heavy duty posi unit. this is a daily driver, but yes i am willing to sacrifice a LITTLE bit of smoothness in trade for a more solid, reliable traction method.

and although everything i read points me toward the sterling 10.5" rear end for my truck, when i look up the available gearsets they all come up as 10.25" gearsets, does this mean i have a 10.25 or 10.5 rear end ??

do you guys have any particular brand you would go with over another as far as the actual ring/pinion sets and rebuild kits (bearings/seals/shims etc), or should i just go with the best deal ? i mean i'm pretty sure i can't go wrong with any of the major names like yukon gear, jts gear, usa gear ???

i've also seen different listings for my rear end depending on where i'm looking, some say it's a 31spline, some say it's a 35spline. some say 10.5" , some 10.25" .. the only thing i DO know for sure is the front end is a dana 60 reverse rotation...

vehicle is a 2004 F250 4x4 crew cab 3.73's / 5R110 35" tires 500+HP
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post #2 of 18 (permalink) Old 04-24-2008, 01:21 PM
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Re: need info on posi's and gears...

I don't like the Auburn limited slip's personally. They are pretty jerky and make some squeaking noise now and then. I've only had them in rear wheel drive cars so it could possibly be different in a heavy truck like these.

The Eaton Posi unit is a very good option. I have driven many vehicles with these in them including a 02 CC 4x4 2500HD. Yeah it's a Chevy gasser but the stock posi unit is an Eaton Posi just like you are looking at for your truck. There was basically no noticable characteristics of any jerking or harsh in-out feeling of it. It would spin both tires in every single condition that I ever had tires spinning. Mud, snow, ice, gravel, dry pavement, etc. always spins both tires.
I have had this type of posi create a little bit of a problem when trying to turn on icy or snow packed roads in RWD cars before but I didn't have that problem in this truck. I think it was probably due to the weight of the vehicle.

The TrueTrac I have no experience with but from the reviews that I have read when people have them I think it is a great option. I have seen a couple of reviews from hardcore Jeep and 4x4 guys that were extremely impressed by the function of it. Also the high performance street car and muscle car crowd like them as well.

Just a word of caution - I know for a fact that you do not want to run syntetic oil with the Eaton Posi or the True Trac. I don't know about the Auburn.

As far as gears go I have never had much luck with getting a good set of gears that didn't make noise from any aftermarket company, Richmond included. I would suggest a set of OEM gears. That's not to say they won't make any noise either but I think you will have a much better chance with OEM.

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post #3 of 18 (permalink) Old 04-24-2008, 02:49 PM
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Re: need info on posi's and gears...

I swapped from the oem 3.73 to the 4.10 in my 2k SD, it was a waste IMO. If I didn't get the old gears back after the swap,I'd swear the gears never were changed. If you are going to swap, go to a 4.30 or a 4.56.
I swapped 3.73's in a Bronco2 to 4.56's and it was great! I ran Auburn posi in the Rr and a Detroit true trac in the Fr. Obviously the lil truck was lighter, but it made a HUGE difference. I was running 35's, it was a nice toy.
For what you're doing(no towing), I'd go for a Detroit soft locker probably.

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post #4 of 18 (permalink) Old 04-24-2008, 08:04 PM
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Re: need info on posi's and gears...

My buddy has a true-trac in the rear of his 84 blazer with 36" swampers and 4.56 gears and he absolutely loves that thing it engages everytime it should and stays open when it should.

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post #5 of 18 (permalink) Old 04-25-2008, 04:00 AM Thread Starter
 
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Re: need info on posi's and gears...

Quote:
Originally Posted by racehauler View Post
I don't like the Auburn limited slip's personally. They are pretty jerky and make some squeaking noise now and then. I've only had them in rear wheel drive cars so it could possibly be different in a heavy truck like these.

The Eaton Posi unit is a very good option. I have driven many vehicles with these in them including a 02 CC 4x4 2500HD. Yeah it's a Chevy gasser but the stock posi unit is an Eaton Posi just like you are looking at for your truck. There was basically no noticable characteristics of any jerking or harsh in-out feeling of it. It would spin both tires in every single condition that I ever had tires spinning. Mud, snow, ice, gravel, dry pavement, etc. always spins both tires.
I have had this type of posi create a little bit of a problem when trying to turn on icy or snow packed roads in RWD cars before but I didn't have that problem in this truck. I think it was probably due to the weight of the vehicle.

The TrueTrac I have no experience with but from the reviews that I have read when people have them I think it is a great option. I have seen a couple of reviews from hardcore Jeep and 4x4 guys that were extremely impressed by the function of it. Also the high performance street car and muscle car crowd like them as well.

Just a word of caution - I know for a fact that you do not want to run syntetic oil with the Eaton Posi or the True Trac. I don't know about the Auburn.

As far as gears go I have never had much luck with getting a good set of gears that didn't make noise from any aftermarket company, Richmond included. I would suggest a set of OEM gears. That's not to say they won't make any noise either but I think you will have a much better chance with OEM.
yeah i've heard the richmonds are very noisy also..
i don't run synthetic fluid anyway so that's no problem for me.

actually i never even considered the fact that 4.10's are available factory gears, but as i look around, they are actually about twice as much money as the yukons or other brands... i don't mind a little noise, so i'll probably not pay the extra just for factory gears...
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post #6 of 18 (permalink) Old 04-25-2008, 04:05 AM Thread Starter
 
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Re: need info on posi's and gears...

Quote:
Originally Posted by OptimusStroke View Post
I swapped from the oem 3.73 to the 4.10 in my 2k SD, it was a waste IMO. If I didn't get the old gears back after the swap,I'd swear the gears never were changed. If you are going to swap, go to a 4.30 or a 4.56.
I swapped 3.73's in a Bronco2 to 4.56's and it was great! I ran Auburn posi in the Rr and a Detroit true trac in the Fr. Obviously the lil truck was lighter, but it made a HUGE difference. I was running 35's, it was a nice toy.
For what you're doing(no towing), I'd go for a Detroit soft locker probably.

i'm not trying to make a huge difference, i'm looking for just enough gear to get the rpm's up just a little bit to help out with spooling the turbo, and drop the egt's a little bit.. i'm running 35's and i just want to kind of get back to stock gear ratio, i don't have an issue with available horsepower, so i'm not gearing it because i need the help... i have no problem w/acceleration or being able to spin the tires any time i want, i just need a small bump in rpm
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post #7 of 18 (permalink) Old 04-25-2008, 02:46 PM
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Re: need info on posi's and gears...

Sounds like you might be happy with the 4.10's with 35" tires. I didn't notice much/if any performance change (turbo spool up and egt's dropping). That might have been the injectors/programming I had at the time too.
The 37" or bigger tire crowd seems to go the 4.30's route.

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post #8 of 18 (permalink) Old 04-26-2008, 04:03 PM Thread Starter
 
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Re: need info on posi's and gears...

i have large nonvgt turbo and larger injectors too.. i've decided to go to a 4.30, and i WILL be getting the detroit true trac, i just dont want the headache of running the locker on the street...

thanks man
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post #9 of 18 (permalink) Old 04-29-2008, 02:29 AM
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Re: need info on posi's and gears...

I'd go Detroit, and either the true-trac or locker.

I doubt with all the money you have in your truck you'll really be offroading...


Truetrac if you tow or see snow...
locker otherwise..

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post #10 of 18 (permalink) Old 04-29-2008, 02:30 AM
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Re: need info on posi's and gears...

Didn't see your last post, nevermind...

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