Ford Muscle Cars Tech Forum banner

1 - 20 of 20 Posts

·
Subscriber
Joined
·
767 Posts
jack up both sides.
spin one wheel forward.
if the other wheel spins forward- its posi.
if the other wheel spins backwards- its an open differential.
 

·
Registered
Joined
·
408 Posts
I cant agree as I thought the same until I got my 66 Falcon. I jacked it up and turned the driveshaft and neither wheel turned! Then I turned a wheel and the other went opposite. Then I bought 3 different center sections thinking my rear was bad. Before changing anything I managed to get the 302/C6 running and took her around the block. Ran so good I just had to do a burnout. Guess what??? It had a posi!! I was shocked! :eek:
 

·
Registered
Joined
·
977 Posts
Discussion Starter · #4 ·
When I get the 50years of dirt road film off maybe I'll find the tag. I'll post the letters / numbers so y'all can decode it.
 

·
Registered
Joined
·
152 Posts
If no tag is available,......jack it up till both tires are free,...put it in neutral,...turn one wheel by hand, if the other wheel is turning in the same direction...they are linked by clutches and pressure plates....indicative of a limited-slip.
 

·
Premium Member
Joined
·
5,393 Posts
Do a burnout.
One line of rubber = open.
Two lines of rubber = pos traction.
No rubber = you need more cubes. :)
 

·
Registered
Joined
·
10,327 Posts
I cant agree as I thought the same until I got my 66 Falcon. I jacked it up and turned the driveshaft and neither wheel turned! Then I turned a wheel and the other went opposite. Then I bought 3 different center sections thinking my rear was bad. Before changing anything I managed to get the 302/C6 running and took her around the block. Ran so good I just had to do a burnout. Guess what??? It had a posi!! I was shocked! :eek:
A) That's is impossible by your description. Something must turn when you turn the driveshaft - unless it's broken, which B) it's not as you have differential turning with the tires, and it drives, again indicating an open rear or worn-out limited-slip, and C) both tires spinning does not mean you have a 'posi' (limited slip or locker), as an open rear will spin both tires if the traction on both tires is equal or other conditions (see below). Please confirm you statements or describe it in different terms to solve any confusion. For example, you can turn one axle without the driveshaft turning, or turn the driveshaft and only one axle turn - but not the driveshaft and nothing turn.
Do a burnout.
One line of rubber = open.
Two lines of rubber = pos traction.
No rubber = you need more cubes. :)
I like that. ;) But to be technically correct, a clutched limited-slip (Traction-Lok, Equa-Loc, etc.) can spin just one tire, and an open carrier can spin both under various conditions. A worn or shimmed open carrier can also act just like a limited-slip through gear binding (in-fact, a common eBay rip-off done on-purpose and sold as "posi"). A spool or locker must spin both. Not trying to be brutal with either of you here (especially when DanV's quote is like a good bumper sticker), but I don't want anyone to assume the wrong things.

David
 

·
Premium Member
Joined
·
5,393 Posts
Now there's a thought........Bumper Stickers.

But seriously, if the car has that much dirt around the 50 year old pumpkin that he can't see the tag, then it must be original.
And if it's original, then check the code on the VIN plate.
Also, how many 352s would have been equipped with a posi-traction rear?
 

·
Registered
Joined
·
408 Posts
A) That's is impossible by your description. Something must turn when you turn the driveshaft - unless it's broken, which B) it's not as you have differential turning with the tires, and it drives, again indicating an open rear or worn-out limited-slip, and C) both tires spinning does not mean you have a 'posi' (limited slip or locker), as an open rear will spin both tires if the traction on both tires is equal or other conditions (see below). Please confirm you statements or describe it in different terms to solve any confusion. For example, you can turn one axle without the driveshaft turning, or turn the driveshaft and only one axle turn - but not the driveshaft and nothing turn.
I like that. ;) But to be technically correct, a clutched limited-slip (Traction-Lok, Equa-Loc, etc.) can spin just one tire, and an open carrier can spin both under various conditions. A worn or shimmed open carrier can also act just like a limited-slip through gear binding (in-fact, a common eBay rip-off done on-purpose and sold as "posi"). A spool or locker must spin both. Not trying to be brutal with either of you here (especially when DanV's quote is like a good bumper sticker), but I don't want anyone to assume the wrong things.

David

Unfortunately I am not giving a false statement here. This is exactly what happened to me in my 66 Falcon with an 8 inch rear. I bought multiple center sections thinking the rear end was toast since neither wheel would turn when I tried to turn the driveshaft. When I turned a wheel the other wheel sometimes would turn the opposite but it was so loose it barely grabbed. However once I applied power I did a posi burnout twice. Maybe it was because the car hadn't driven under power from 97-09 when I got it?? I don't know but I was as shocked as anyone else would be when I was able to lay rubber with both tires. If I was making this up I would never have stated it. Maybe the spider gears were broke? One caught when power was applied? I am in no way offended and not looking to argue just stating my CRAZY story.
:)

Now on a second instance in my 66 Ranchero I bought a 4.11 limited slip used at a swap meet and installed. It spun correctly however when I went to spin the tires it was a one wheel wonder until I installed a more powerful motor and a very high 3K rpm stall. The stall was way too high as it slipped until 3K then jumped but once it hit I was able to burn both tires with no problems.
 

·
Registered
Joined
·
124 Posts
When you spin the driveshaft you need to put your hand (and have a helper for the other side) on the tire and put some drag on it. They will both spin with posi. Just spinning the driveshaft is not a true test.
 

·
Registered
Joined
·
977 Posts
Discussion Starter · #11 ·
Haven't had time to do any test or clean it. Been rearranging things for when I go pick up the 66 Monday..
J C , Was you heading East on 190 around noon today in L V H ?
 

Attachments

·
Premium Member
Joined
·
297 Posts
I have to add one thing to this thread, A friend and I were buying a couple of FE's engines at a guys house and he had a rear end for sale. He said it was a posi trac rear end but my friend looked where the axles go in the rear end and taught me something...If you look where the axle splines are in the rear end,a posi rear end has a separation between the splines ,a rear end that is not a posi has splines with no separation in them.Needless to say ,it wasn't a posi,but the one I bought the next day was. I guess that's about the best way I can describe it,only thing is ,you need to have the rear end apart.Let me know if that's wrong, but that is how it was taught to me.

When we were installing different axles in my 64 Gal I had a heck of a time getting the drivers side axle in because the splines on the posi trac weren't lining up.I had to keep turning the drive shaft to get in line .
 

·
Premium Member
Joined
·
34,855 Posts
I have to add one thing to this thread, A friend and I were buying a couple of FE's engines at a guys house and he had a rear end for sale. He said it was a posi trac rear end but my friend looked where the axles go in the rear end and taught me something...If you look where the axle splines are in the rear end,a posi rear end has a separation between the splines ,a rear end that is not a posi has splines with no separation in them.Needless to say ,it wasn't a posi,but the one I bought the next day was. I guess that's about the best way I can describe it,only thing is ,you need to have the rear end apart.Let me know if that's wrong, but that is how it was taught to me.

When we were installing different axles in my 64 Gal I had a heck of a time getting the drivers side axle in because the splines on the posi trac weren't lining up.I had to keep turning the drive shaft to get in line .
That don't make a lick of sense to me...
 

·
Registered
Joined
·
10,327 Posts
...If you look where the axle splines are in the rear end,a posi rear end has a separation between the splines ,a rear end that is not a posi has splines with no separation in them.
...
When we were installing different axles in my 64 Gal I had a heck of a time getting the drivers side axle in because the splines on the posi trac weren't lining up.I had to keep turning the drive shaft to get in line .
That is correct. Open differentials only have the two side gears (spiders) that the axle shafts go into, one on each side. A Ford Trac-Lok or Equa-Loc has the clutch splines on the left (driver's) side, so you have two sets of splines on that side. If they are not lined-up, it makes getting an axle in quite a chore. If you can't see the splines well, a dental pick or piece of wire can be drug across the splines to feel if there is a tiny separation between the sets.

Another clue I use is that open diffs only have one and sometimes two thumb-size lube holes in the carrier. Factory limited-slips have four. This is handy when you only have pictures of one side, and if you can see two holes 90° apart at any one time, it's a 4-holer Trac-Lok.

In-case you're wondering - yes, the parts below are well-broken. Waaay too much HP and it sheared the carrier case right in-half at the shiny line. I have a sneaky feeling it had been dropped sometime, starting a small crack that led to the failure.

David

Here is a shot of the inside driver's side showing the extra splines. The side gear (spider) goes right on-top of this giving two sets of splines on this side:


When shopping for factory LSDs, you can look for the lube holes in the carrier body. Note how there are four in this LSD, so if you can see two at any time (90° apart), you have a Trac-Lok. Open carriers usually only have one lube hole:
 

·
Premium Member
Joined
·
297 Posts
That don't make a lick of sense to me...
Sorry Fe for the poor description, but in this pic of my old rear end you can see the front splines and the rusty looking splines are right behind the front splines.I guess it's better to say the splines look like they are in two pieces.

This guy tried to push a rear end off on me saying it was a traction lock and my friend got me off to the side and told me about the spline separation inside the rear end.Being a rookie at all this ,I was grateful for the knowledge at a critical time, and I wanted to pass this info on to any other rookies out there.
Red
 

Attachments

1 - 20 of 20 Posts
Top