8 Inch POSI rear ID and lube type?.

8 Inch POSI ID and lube?.

Acquired this 8" Ford Posi 3.80:1 rear. I would like help to identify the Brand and/or type of this POSI unit . I need to get POSI lube and need recommendation depending on type ID'd.

ALSO how does this POSI work?...

thanks

(IF PB allows:)



.

74 Maverick 250 Vortech V2-SC Blo-Thru 2Bbl Holley.



haev fun

 

85w-140 conventional gear oil and a limited-slip additive. Without the additive, the "posi" won't work.

 

is his a clutch type?
my old possi took 85w-140 conventional gear oil and no limited-slip additive.
my new possi takes 85w-140 conventional gear oil and no limited-slip additive.

 

Looks like a trac loc unit due to the machined surfaces that the ring gear bolts go through, I would put the 85-140 and the additive cant hurt to put additive in it anyways

 

found this in a Google search...

"The use of any additive in locking rear axles is not recommended. Rear axle additives are designed for use in limited slip differentials which are normally installed in cars. the use of additives will delay the engagement of the locking mechanism and may decrease axle life."

Moser...
`"Gear oil additives that drastically reduce friction will actually reduce the performance of gear differentials. The internals of the diff get too slick to generate adequate friction – reducing the differential’s effectiveness – reducing its ability to drive both wheels."


then there was this...I have never heard of anyone changing that often...

"The rear axle should have the gear lubricant changed every 7,500 miles (12,000km). If equipped with a limited slip differential, be sure to add 4 oz."

 

I can promise if it's a clutch type Ford Equa Lock(what was usually in 8") or Traction Lock, it'll chatter horribly without the friction modifier... If it doesn't then it's at least 80-90% worn out...

 

I want to know how well the blow through setup works on that 6! Something I've always likes about a 6.

 

Interesting the 8" POSI type can't be positively determined. I spent a lot of time searching web pics to match and maybe early Mustang (@ 64-65?) but maybe not, got it locally so may look into history. Supposed to be swap from recent build for different gears. Seems to be POSI as described ... Case is C7xx (67)

Meanwhile it's going in the '74 Maverick , just swapped '76 Disc spindles, cut coils, sway bar, KYB's.

have fun

 

I believe what he has would be a limited slip rather than a locker. Limited slip being engaged with clutches and locker meaning mechanically locked as in no slip whatsoever. No offense Frank, you no doubt know the difference but others may not. My only experience with the additive has been in GM rears where it is recommended but I have no idea with Ford yet. Guess I better look at the instructions for my Trac Lock!

 

While I was out pulling the OEM 2.79 (?) , I took another look and I think I was skunked and "POSI" may well be a stock carrier , 3.80 gears with a spool inside ...

What is it like driving with a 3.80 spool?, this is a road car not a track car ..

How involved to swap in a true posi with the 3.80 gears?

thanks

 

You have to be very careful with a spool especially on slick roads, making fast passing of a car with just pulling out fast to get around them can be hazardous and in parking lots you will get a lot of tire noise. I ran a mini spool in a street/drag car and found myself in a lot of scary situations with it and will never use one on the street again.

If you can look clear through the spot that the axle go in and see a bar in there then it probably has a mini spool in it. Poor mans posi

 

yes... I was responding to the comment. "cant hurt to put additive in it anyways."

 

Sure looks like a spooled setup to me. Spools SUCK on the street and can be quite dangerous! Be prepared for some tire howl and light screech on tighter turns too.

As for the lube requirements if it were actually a clutched posi?.. ALL the OEM's make their own versions of friction modifiers for a reason. I generally try to stay mfgr specific(Chevy formulations in the Chevy's and Ford's in a Ford, etc) but you do need to be careful what base oils are mixed n matched. Some gear lubes already formulate with added friction modifier packages and is possible to have too much. I usually always try to stay full synthetic on everything oil related and there are some posi additives which specifically cater to full synthetics. Hope that helps.

 

Powerband- you and frank are on the same page. In my experience, Most all true posi setups have recessed bolts in ring gear. Flush mount in this situation looks like mini spool, or open gears. I’ve been duped before many years back when I purchased a 3.70 “Trac loc” from a reputable guy on eBay. I never second guessed it because both tires spun instead of just one wheel peel, but everytime id go around a corner, my car would jerk side to side and make a popping sound like my lug nuts were about to blow off and my axles were binding. But it turns out, it was an open carrier and the spider gears exploded and somehow fused together making both axles stay engaged.

As for the trouble, you’ll take your carrier bearing cap bolts and caps off, then take out ring gear bolts and pull out your carrier. Get you a new Trac loc, true Trac or locker carrier and have someone that knows how to set the lash put everything back together. It def looks like a 3.80 given how thick that ring gear is in picture and you can always count the teeth. Good news is you can reuse your ring and pinion, (you’ll need longer bolts) bearings etc and so forth you just need a different carrier rather than a mini spool or open one. Ebay has some cheap “posi” carriers for $275 for clutch style, or 400-500 for gear or locker style. Hate that you got screwed over and hope you got a good price on it. Typically if you see a complete refurbed 3rd member going for $500 complete, then most likely it has new gears but running a cheap spool or mini spool because they are a lot cheaper than the alternatives. Another way to tell if it’s open vs locker or spool is if you stick your axles in and rotate the yoke. If they spin same direction you have locker or spool, if they turn opposite, then it should be open. Hope this helps some