posi conversion.

[samericsson67]

hey, i'd really like to do a conversion sometime for my '69. is it worth it? i've also heard very large price differences about it. some say it could be done for like 300 and others have said like 2000. does anybody have a good idea as to what it costs?

[HIO Silver]

Is it worth it to you? Btw, "Posi" is a GM term as in "posi-traction". Ford's version was "Trac-Lok" or "Traction Lok" both of which refer to a limited slip differential.

You have a choice to make: Either a limited slip differential or a locking differential. Using Summit Racing for prices (of course excluding labor), a limited slip is around $350 and a Detroit Tru-Trac Locker is $479. Remember to factor in the labor cost to set up the gear tooth pattern.

In the middle but installable in the home garage without special tools is Richmond Gears' Powertrax.. it is also referred to as a "lunchbox locker" at $494.

So, that puts it at around $500 to $800 for the Tru-Trac or Trac-Lok assuming you remove the center section and drop it off along the parts to the drivetrain specialist. At home, the cost is around $550 plus your sweat equity.

[basketcase0302]

What axle do you have in your truck?

[sargentrs]

In the middle but installable in the home garage without special tools is Richmond Gears' Powertrax.. it is also referred to as a "lunchbox locker" at $494.

I put the PowerTrax No Slip in mine. Installation was a breeze. At $500 it was a bit pricey but I liked the concept, no clutches, no clunking, and it got good reviews on the muscle car sites I researched. Haven't actually driven with it yet but expecting good results. We'll see

[elgemcdlf]

An inexpensive way to get a Limited Slip under your truck is to use the rear axle from an Explorer (bolt circle is different). Many came with Limited Slip & ratios are all over the board. I am in the process of putting a Limited Slip in my IRS. I had to tear it down to have the spyders machined (the IRS are slightly different that solid axle). No big deal taking it all apart. The local Pull A Part has complete rear axles with discs for $118. Plan on spending a day doing the pull to get exactly what you want. You will most likely be swapping parts back & forth to get what you want. You know, you found your axle with discs & Limited Slip but the ratio is not what you want. Off you go searching for the ratio you want. Pull it out & swap it into the axle housing & Limited Slip unit. Now you have exactly what you want without buying the same parts multiple times. By the way the Explorer is a 31 spline axle unit.

When you get it home be sure to tear it down & check all the discs in it. Rebuild kits are in the $80 range.

[ultraranger]

hey, i'd really like to do a conversion sometime for my '69. is it worth it? i've also heard very large price differences about it. some say it could be done for like 300 and others have said like 2000. does anybody have a good idea as to what it costs?

Since you didn't specify what type rear end you're talking about installing a limited-slip differential in, I'll presume you are talking about a Ford 9-inch rear.

The Ford 9-inch rear was first installed in Ford passenger cars & trucks starting in 1957. The first differential Ford used that directed power to both rear wheels was called the Equalok. Some time in the early '60s, Ford came out with the Limited-Slip differential. I can't find any differences in the Equalok & Limited-Slip differentials, other than a name change.

In 1969, Ford introduced the Traction-Lok differential. This is a much better design than the Equalok/Limited-Slip but the '69 model Traction-Lok is the worst year Traction-Lok differential to have due to (4) large holes in the casting on the drivers side half of the diff. Starting in 1970 ('70-'85), the casting had a solid case (no holes on the drivers side half of the differential).

'Holes' shown in 1969 Traction-Lok differential:






1970-1985 Traction-Lok diff on left (no holes in drivers side of casting). Weaker (4-hole) 1969 Traction-Lok diff on right and what can happen to it when enough torque on the unit cracks the casting between the holes:



http://ultrastang.com/info2.php

http://ultrastang.com/info6.php

New Ford Traction-Lok differentials can be bought on ebay for around $300-$400 dollars. Cost of bearings, seals, gears & assembly of the 3rd member would also have to be factored in.