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help with testing my 8.8, 3.55 limited slip

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Jon M

help with testing my 8.8, 3.55 limited slip

Good morning, folks.

It's getting warmer so I'm picking up where I left off a few months ago with Dolly, the 1984 f150 4X4 in-line 6. One of the many things I have on my to-do list is to learn how to check the integrity of the factory limited slip on my rear differential.

YouTube, tells me to just keep one wheel one the ground and put a torque wrench on an axle nut and incrementally go up in torque value. Well, we don't have axle nuts on these trucks so I figure a lug nut will have to do. But aside from that, I'm looking for the original torque specs would be on the factory limited slip so I can see how effective it's going to be and if I need to (eventually) replace it. Unfortunately, this rear-diff is not native to Dolly but the truck came to me with it so I have no idea what generation it is. Based on the smaller, ill-fitting front sway bar that came on the truck (it's off now), I'm wondering if it's from a Ranger - but I suspect most of the limited slips will be spec'd at the same or similar value across many generations.

All that to say, I want to find out how much abuse this thing has sustained - is there a listing in this website's documents with the limited slip torque values I should be trying to match during the test?

Jon
1984 Single Cab F150 300/4.9L i6 named 'Dolly'
4X4 - rear 3.55 limited slip, Dana 44
and nothing fancy ... yet.

Gary Lewis

Re: help with testing my 8.8, 3.55 limited slip

Administrator

Jon - We didn't have the section from the factory shop manual on the site for the Traction-Lok diff. So I added it on the page at Documentation/Driveline and then the Rear Axles & Differentials tab, the Instructions tab, the Ford 8.8" tab, and finally the Ford Traction-Lok tab.

It says: Minimum rotating torques required during bench check after assembly or in vehicle with one wheel on the ground for original clutch pack. 41 Ft-Lb/30 N-m

You aren't really going to be able to test that directly by placing a torque wrench on a lug nut because that's assuming you are on the axle itself. However, you can test it if you measure the distance from the center of the axle to the center of the lug and do some math. And you'll have to make sure the torque wrench is directly in line with the two centers for that to work.

Also, note that on Page 8 there's a table that shows what the tag on the axle should read depending on what gear ratio you have. That might tell you if you have the original axle or not. But there's another number on the tag that we can cross reference as well if you want.

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

Jon M

Re: help with testing my 8.8, 3.55 limited slip

Thanks Gary! I guess it's back to math class for me. And thanks for adding the traction-loc section. I look forward to digging into it.

Jon
1984 Single Cab F150 300/4.9L i6 named 'Dolly'
4X4 - rear 3.55 limited slip, Dana 44
and nothing fancy ... yet.

Gary Lewis

Re: help with testing my 8.8, 3.55 limited slip

Administrator

Good luck! And if you want to brainstorm the math then give us some measurements and we'll see what we can do.

Gary, AKA "Gary fellow": Profile

Nothing Special

Re: help with testing my 8.8, 3.55 limited slip

If you can get the torque wrench perpendicular to a line from the center of the axle to the lug you are using you don't need to do any math. The lever arm will still be the same as if you were on center.

Bob
Sorry, no '80 - '86 Ford trucks
"Oswald": 1997 F-250HD crew cab short box, 460, E4OD, 4.10 gears
"Pluto": 1971 Bronco, 302, NV3550 5 speed, Atlas 4.3:1 transfer case, 33" tires
"the motorhome": 2015 E-450-based 28' class C motorhome, 6.8L V-10
"the Dodge": 2007 Dodge 2500, 6.7L Cummins

Gary Lewis

Re: help with testing my 8.8, 3.55 limited slip

Administrator

Nothing Special wrote

If you can get the torque wrench perpendicular to a line from the center of the axle to the lug you are using you don't need to do any math. The lever arm will still be the same as if you were on center.

Yes, absolutely. Since the lug nut should be torqued roughly twice what the drag should be the nut should not rotate. Perfect!

Gary, AKA "Gary fellow": Profile

mat in tn

Re: help with testing my 8.8, 3.55 limited slip

just a thought. "if" one had an axle/hub puller then the center attaching point could hold a nut/ bolt combo which gets torqued first at say 60ft lb. then that could be used as an aligned torque testing point.

Gary Lewis

Re: help with testing my 8.8, 3.55 limited slip

Administrator

Yes, that should work nicely.

Gary, AKA "Gary fellow": Profile

Jon M

Re: help with testing my 8.8, 3.55 limited slip

In reply to this post by mat in tn

Hey there Matt in TN, I dug around my shop and found exactly that! So it looks like I won't have to go back to school after all. But all of that is on hold as I address switching out the track lock clutch pack. I didn't even know that was a thing until I dug into the service manual chapter that Gary uploaded. It turns out that is a significantly cheaper alternative than replacing the entire LS assembly.

Unfortunately I don't know the age of this rear differential because the tag isn't on it. I do have the front Dana44 tag but that won't help with the rear diff. The reason I need the age, I think, is to buy the right Track Loc clutch pack. Can anyone weigh in on how I might proceed getting the right part?

Jon
1984 Single Cab F150 300/4.9L i6 named 'Dolly'
4X4 - rear 3.55 limited slip, Dana 44
and nothing fancy ... yet.

mat in tn

Re: help with testing my 8.8, 3.55 limited slip

there are two different models used in these. the first generation comes from the fact that the earlier f100s had a small bolt pattern and therefore had a smaller centering hub for the front disc. this had to be carried to the rear axles centering hub also for the wheels to be interchangeable. all this to say that the centering hub will be about 2-7/8" where the next generation is about 3-1/4". I'm not measuring exactly but the scale is the point. the earlier axles that had the smaller centering hub also have a different size locking tab inside the carrier for the c clip requiring a different size center pin. this is the most relevant difference here. the center pin difference will be 3/4-7/8 approx. I can measure them for you if needed. these are NOT interchangeable withe the axles. axle/carrier combos must be kept together with proper parts. so, if you have the smaller centering hub then you have the smaller pin version of the trac loc.

mat in tn

Re: help with testing my 8.8, 3.55 limited slip

funny thing that i just noticed. your trucks name is dolly. I have a dolly also. I'm curious about the reason.

Gary Lewis

Re: help with testing my 8.8, 3.55 limited slip

Administrator

In reply to this post by Jon M

The way I'm looking at the master parts catalog there are two different 8.8" locking axles 1983-86 and 1987 & later. If you look at the page at Documentation/Driveline/Axles & Differentials and then the Rear Axles & Differentials tab followed by the Applications Listing tab you'll see that the 8.8" came out in 1983. And that all 8.8" applications with a locking diff use Parts List #238.

Then if you go to PL #238 you'll find "4026 Differential assy, (locking)":

E3TZ 4026-A Use with axle #WFL-A,B,B1,C,C1,D,E,F,H,365A,365B,805A,807A,809P-1983/86

E7TZ 4026-C Use with axle #805D,807D,809S,813P,815D,817P,835A,837A,845A,847A— 1987/

That's all I know.

Gary, AKA "Gary fellow": Profile

Jon M

Re: help with testing my 8.8, 3.55 limited slip

In reply to this post by mat in tn

Mat in TN,

Well, the story of Dolly's name goes back to her predecessor that I jokingly named 'Jolene' after the Dolly Parton song about a woman trying to take her man. I thought I was being clever in making the correlation to that song in that 'Jolene' the truck was trying to take my wife's man (me). Well, in true form to the song, and Dolly Parton's story behind the song, Jolene was indeed no good. She had some serious frame issues, and was smog-deleted, which my area requires and I just didn't have it in me to fix all that. So I salvaged just about everything I could from her and found another truck with a better chassis that had lived an overall much better life. I'm nothing if not consistent, so I stuck with the Parton references and named this one 'Dolly'. I won't be able to gussy her up in such a way that truely honors her namesake, but when I'm all finished I plan on putting a decal of one of Dolly Parton's most famous quotes on the back window; "it takes a lot of money to look this cheap."

Gary,

The guy who owned this truck before me got back to me and confirmed that the 8.8 axle he put on it was from a 1986 frame. This being the case, can you speak to what Traction-Lok rebuild kit I would need? Part of wonders if this would be the same differential was placed in Mustangs of that vintage, in which case finding a rebuild kit is fairly easy as they are still made and sold by Ford Performance. Thoughts?

Jon
1984 Single Cab F150 300/4.9L i6 named 'Dolly'
4X4 - rear 3.55 limited slip, Dana 44
and nothing fancy ... yet.

Gary Lewis

Re: help with testing my 8.8, 3.55 limited slip

Administrator

Jon M wrote

Gary,

The guy who owned this truck before me got back to me and confirmed that the 8.8 axle he put on it was from a 1986 frame. This being the case, can you speak to what Traction-Lok rebuild kit I would need? Part of wonders if this would be the same differential was placed in Mustangs of that vintage, in which case finding a rebuild kit is fairly easy as they are still made and sold by Ford Performance. Thoughts?

The MPC says your differential is "E3TZ 4026-A". And according to the 1980/1989 Ford/Lincoln Mercury Cars MPC that differential wasn't used in any car. Sorry.

Gary, AKA "Gary fellow": Profile

mat in tn

Re: help with testing my 8.8, 3.55 limited slip

the main difference between the car trac loc and the truck version is the axle splines. cars have 28 and the trucks have 31. this is achieved at the spider gears but the clutch pack and rebuild wear parts are the same.
as to "dolly". I bought a wrecked 93 flareside. to do a rebuild with. I wanted to try doing a patina paint job and so I went through the layering process. I spent the better part of a week wet sanding each panel to the point I liked before doing the clear coat. while sanding on the fiberglass rear quarters I got thinking that "this chick has real hips" then I got thinking about that same quote about taking a lot of work to look this cheap and it was set. so, I called the truck dolly, and she is now well accepted as a family member. however, my mother thinks it's a tribute and cannot understand that to me it's an insult with a grin. I am not a fan of D.P.