Posi rear end????

Paranoid! · Post by **Paranoid!** » April 13, 2010, 11:32 am

Ok people...
Is there any way to tell a limited slip from a posi yoke visually without cracking it open??
And also.....
What will fit my original 1966 axle??.....66 to 79?
mustang,ranchero,F150? etc........

Thank's

64 f100 · Post by **64 f100** » April 13, 2010, 11:40 am

should ber a tag on the rearend under one of the nuts. This is usually on the passenger side about middle of the axle. On it will be located at the bottom right next to the nut, numbers. This will be your gear ratio. Example 3 25, if posi it will read 3 L 25. The L denotes traction lock which is Fords term for a limited slip. the L denotes posi regardless of geear ratio. No tag? Jack up the rear end, chock front wheels first, ratate one wheel. If other wheel spins the same way as your ratation it is a tracloc, if it spins the other, open.

Rich

Paranoid! · Post by **Paranoid!** » April 13, 2010, 11:50 am

64 f100 wrote:
The L denotes traction lock which is Fords term for a limited slip.
the L denotes posi regardless of geear ratio.
Rich

So if ther is an "L" in there, it's a posi traction...?

Riverside Racer · Post by **Riverside Racer** » April 13, 2010, 1:48 pm

Mine was really easy to tell...

It has a tag on the rear cover that said "Use Limited Slip Diff Lube Only!

I thought I read here that if your truck was ordered with a Ltd Slip Diff, you were given the Dana rear end.

Provided that you still have the original rear end in your truck!

The Big M · Post by **The Big M** » April 13, 2010, 2:20 pm

Paranoid! wrote:Ok people...
Is there any way to tell a limited slip from a posi yoke visually without cracking it open??
And also.....
What will fit my original 1966 axle??.....66 to 79?
mustang,ranchero,F150? etc........

Thank's

I'm not sure I understand the first part of the question. "Posi" is a GM term that's been co-opted to mean any limited slip differential, regardless of manufacturer. So the two are one and the same. If you're asking about limited slip vs. open, then Rich's answer sums it up nicely.

As for the second part, if your truck was originally delivered with an open 9" differential, I believe just about any 9" centre section will be interchangeable, but the issue will be the axle shafts. The Ford 9" was produced in 28- and 31-spline variants, with large and small bearings, and in a mind-boggling array of lengths.

Some light reading on the subject can be found here:

http://www.kevinstang.com/Ninecase.htm

BarnieTrk · Post by **BarnieTrk** » April 13, 2010, 9:54 pm

Under what truck -- should I assume you're talking about a 2wd, '66 F100?

If so, I'm fairly certain that FoMoCo did NOT produce any 2wd, '66 F100s with a Ford 9" rear housings and equip them with a limited slip differential.
If the truck was ordered to get a limited slip rearend, FoMoCo would have installed either a Dana 44 or Dana 60.2 rear housing, not a 9".
Most all Dana 44s were equipped with limited slip diffs whereas some of the Dana 60.2s were open diff.

Do you know what rearend you have now - is it a Ford 9", a Dana 44 or a Dana 60.2 housing?

If it is one of the Dana rears, it should have the cover bolted on the rear side of the pumpkin. Look for a tag on one of the cover bolts; as Rich indicated.

BarnieTrk

Hawkrod · Post by **Hawkrod** » April 13, 2010, 11:23 pm

Not only did Ford not use 9 inch limited slip rear ends in Ford trucks in those years, they did not have Trac Locks in those years either. The Trac Lock was a brand new thing in mid 1968, it did not exist prior to that time. Hawkrod

don luster · Post by **don luster** » April 14, 2010, 8:29 am

sorry to disagree with you. Bought a 65 truck from the original owner and it was Limited slip rear end. Maybe a special order because it was a Game warden truck.

Hawkrod · Post by **Hawkrod** » April 14, 2010, 9:10 am

don luster wrote:sorry to disagree with you. Bought a 65 truck from the original owner and it was Limited slip rear end. Maybe a special order because it was a Game warden truck.

Nobody said it wasn't available as a limited slip. What has been said is totally correct, the F100 with a limited slip did not use a Ford 9 inch rear. If you had one that did have a 9 inch then somebody swapped it in. When you ordered a limited slip on a slick F100 you got a Dana built rear end. Hawkrod

Paranoid! · Post by **Paranoid!** » April 15, 2010, 3:06 am

Ok...
Thanks for the info......
Gives me something to chew on.
I can see that I need to dig a little deeper into what I currently have..

6166 Junkyard Dog · Post by **6166 Junkyard Dog** » April 15, 2010, 6:41 am

MY Personal exp. with locking or posi rears are only good for one thing is going straight,, IF YOU VALUE YOUR TRUCK like I did on my 56 F-100 I removed mine since I was tired of being in the ditch in the rain that happened 3 times after the locking rear was removed not a single problem,, but I do no that this was the cause of this truck spinning out either in a circle or just taking off to the median and under a normal speed of 55-60 in rain that this was the cause,, now maybe in 4x4's might be great,, I know in the last 3 F-350 duallys we had we had to keep adding additives cause say when turning off a exit ramp you will here the clutches raising hell or pull into a parking spot then back out it would actually shake the truck,, Took it to Ford said this was common, about every 20000 miles had to change gear lube which was running syn. oil, then buy the additive for the rear ,, well after awhile that gets old doing this,, anyway If I got a F-100 truck I was going to drive everyday or occasionally and came with a locking 9" L rear it will be gone and this is by previous exp nothing that can be looked up in books,, Now if looking for the 9" L rear can be found in many different Ford Vehicles from cars to trucks to vans but if going to a salvage yard be prepared to look at
many, you might crawl under 100 vehicles and not find 1,, last one I found was a under a 68 T-Bird with the N-Case also but thats after looking under many and many,,, anyway Good Luck on looking and if you do install one just be prepared on some of the down faullts

64 f100 · Post by **64 f100** » April 16, 2010, 6:39 pm

Limited Slip rearends can be dangerous, especially on ice. When both wheels will spin, you loose rearend traction on curves . I like to play and learned how to drive one when you were still allowed to play once in awhile. Todays laws and lack of places safe to play make it extremely difficult to learn how to drive offensively. If you watched the cartoon movie Cars, the old Hudson demonstrated a technique of powering thru corners. I knew this technique long before this movie, and practiced out on dirt roads where there was no one around. We are talking Colorado, and the mid 60's. All I can say is learn your limitations with a posi type rearend. Find a big parking lot with no one around in the rain. You can get the feel of what it does and not have to go fast to check it out. An open rearend will slide also, but when you only have one driving wheel, the other is helping hold your arse end in place as it is not spinning persay.

Hawkrod, did they not have the predicessor to the tracloc. I think it was called the equaloc or something like that.

Rich

oldtrucks · Post by **oldtrucks** » April 16, 2010, 6:58 pm

The 61 in my signature when we got it had the dana 44 locking axle with a 3.92 gear ratio. Of course none of the original frame and suspention was used but that is the rear end it was shipped with. I still have it if anyone is interested. It needs completely rebuilt drum to drum. The gears are still good.

6166 Junkyard Dog · Post by **6166 Junkyard Dog** » April 16, 2010, 7:18 pm

I said you might have to crawl under 100, well I must have done 101 cause when I was pulling a bed off today, I looked and stared at the rear on this 72 F-100 and something did not look right,

well anyway I have seen that look and by golly its a 3:L 50 rear but not a 9" its a 9 3/4 31 spline which is rare find in a F-100 truck of course this was a fully loaded short bed truck for 1972 and that this truck has Power Disc Brakes 390/Automatic/ PowerSteering A/C, I know with all the trucks we have parted out I have had several 70/72 9" 31 spline trucks open rears but first like this and the Metal Tag confirms all the info.. so anything is possible...

Paranoid! · Post by **Paranoid!** » April 16, 2010, 7:25 pm

This truck is going to be a weekend driver...
Once done she'l probably never see rain or ice again unless Im caught out on a road trip....SLICK STOCK!!

...

I pulled the tag on my axle and here are the #'s

WDM - J
3.50 6HE 311

Guess I'll search these and see what I can find..

Thanks again people...

BarnieTrk · Post by **BarnieTrk** » April 16, 2010, 9:00 pm

Sounds like to me you've got a common Ford 9" rear end housing with a non-locking differential and a 3.50 ring gear set.
Pretty standard 1/2-ton or F100 equipment...... What did you find out in your search?

BarnieTrk

Paranoid! · Post by **Paranoid!** » April 16, 2010, 11:19 pm

I found that it's difficult to find a place to look up the tag
numbers!!

Thanks for the info!!

6166 Junkyard Dog · Post by **6166 Junkyard Dog** » April 17, 2010, 5:42 am

WDM-J IS Typical 1963-72 F-100 9" non-locking 28 spine 3:50 gear rear end assembly

Paranoid! · Post by **Paranoid!** » April 17, 2010, 11:19 am

Sooooo???
What I should be looking for is a
1963-72, 9" , 28 spine 3:L50..?

BarnieTrk · Post by **BarnieTrk** » April 17, 2010, 1:24 pm

Paranoid! wrote:Sooooo???
What I should be looking for is a
1963-72, 9" , 28 spine 3:L50..?

Russell,
Why don't you just tell us what it is you're trying to do??

If you just want to look at one, look at the one under your own truck!

-- Are your axles shot?

-- Are the bearings and/or gears in your differential carrier (also commonly called the center section, pumpkin or pig) worn out?

-- Do you want to or need to change the center section as well?

If you want to replace yours with one like yours, then you've got many years worth of F100s to be looking under for a replacement housing.

------ Help us help you, Dude!

BarnieTrk

Posi rear end????

Posi rear end????

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Posi rear end????

Posi rear end????