My trucks not stock? Gearing concerns...

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My trucks not stock? Gearing concerns...

86-350-460-dually
This post was updated on .
I bought this truck, thinking it was stock. We've since discovered the coil is not stock, the rear end is probably not stock and it might not have been a dually or 4wd at conception.

I just keep finding new things about it. I was hoping maybe someone could help me identify the make and/or model of the rear axle and if it was stock on this truck.

I'm a little concerned because my speedometer is way off. It starts at zero, but by the time I hit 60 mph, the spedometer is at 82 mph.  Should I be concerned about the gearing on the truck?

Anywho, I suppose first things first.... Is that the stock rear axle?



Adam

1986 F-350, Dually 4WD, C/C with the 460/7.5L
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Re: My trucks not stock? Gearing concerns...

Rembrant
86-350-460-dually wrote
I just keep finding new things about it. I was hoping maybe someone could help me identify the make and/or model of the rear axle and if it was stock on this truck.
That's the onion Gary is always talking about...lol. Each of those new things you find out are a different layer of the onion.

Luckily we have experts on here that can tell you exactly what rear diff that is. I'm not one of those experts, but a quick comparison with the page below tells me that you have a Sterling 10.25" rear diff.

https://www.autoanything.com/drivetrain-differentials/how-to-identify-your-differential

We'll have to wait for Gary or Lebaron to drop by to confirm, but I do know that the F350 trucks had different rear ends depending on whether they had beds on them or not.

In the meantime, you should post a picture of the truck's certification label. It should be on the cab, just inside the driver's door by the striker post. That will identify what was in the truck when it was built.
1994 F150 4x2 Flareside. 5.0 w/MAF, 4R70W, stock.
1984 F150 4X2 Flareside. Mild 302 w/ 5spd. Sold.
1980 F150 4X4 Flareside. 300i6 w/ 5spd. Sold in 2021.
1980 F100 4X2 Flareside. 351w/2bbl w/NP435. Sold in 1995

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Re: My trucks not stock? Gearing concerns...

85lebaront2
Administrator
In reply to this post by 86-350-460-dually
First item, if it was built as a cab and chassis, it should have the Dana 60 rear axle. Quick check without pulling everything apart is the track width. Cab and chassis trucks have a narrower track width than the dually pickups in 1985-86. The 10.25" Sterling rear was introduced in 1985 and the track width was increased, this allowed the between the fender width of the bed to be the same as a single rear wheel truck.

Drive through some water, continue straight and get out and look at the tire track pattern. A cab and chassis or pre 1985 dually pickup will produce what appears as a very wide single track on each side. A 1985 up dually pickup will produce a 4 tire track pattern.

The reason for this is the Dana rear, the center line of the dual wheels is in line with the center of the front wheels, on the Sterling, the center line of the inner dual is in line with the center of front wheel.

Axles ready for parts swapping, rear is an SRW Sterling, same width as a Dana.


SRW width backing plate to backing plate.


DRW width backing plate to backing plate.
Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

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Re: My trucks not stock? Gearing concerns...

Gary Lewis
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It looks like things are pretty well answered, but the rear axle info is here: Driveline/Axles & Differentials.  On the Rear Axle tab you can see the illustration that shows where to find the tag or info on the axle.  Note that the Dana info is on the axle tube.

And from the certification label you can get the axle code and look it up here: Specifications/Axle Ratios.  Use rating info to figure out what it is via the Axles & Differentials page.
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

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Re: My trucks not stock? Gearing concerns...

Rembrant
In reply to this post by 85lebaront2
85lebaront2 wrote
First item, if it was built as a cab and chassis, it should have the Dana 60 rear axle. Quick check without pulling everything apart is the track width.
Hey Lebaron,

Another quick check would be the cover bolts. If you look at the covers in the link I posted above, the Dana 60 cover has 10 bolts, and the Sterling 10.25 has 12 bolts. I have no idea if that is a 100% accurate chart, but if that chart is correct, then his rear diff appears to be a Sterling unit.

The certification label will give us an idea of whats going on here...on what the truck was supposed to be at least;).
1994 F150 4x2 Flareside. 5.0 w/MAF, 4R70W, stock.
1984 F150 4X2 Flareside. Mild 302 w/ 5spd. Sold.
1980 F150 4X4 Flareside. 300i6 w/ 5spd. Sold in 2021.
1980 F100 4X2 Flareside. 351w/2bbl w/NP435. Sold in 1995

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Re: My trucks not stock? Gearing concerns...

86-350-460-dually
Thanks everyone! I took a picture of the certification label and went to the ratio page on Gary's website and found that the 65 rear axle meant that it was supposed to have a "Dana/Spicer" rear axle.  That's as far as I had gotten with it.

Adam

1986 F-350, Dually 4WD, C/C with the 460/7.5L
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Re: My trucks not stock? Gearing concerns...

85lebaront2
Administrator
In reply to this post by Rembrant
Correct by the information you shared. I did a cover bolt count and came up with that. He could have an SRW Sterling as the wheels would fit like they do on a Dana and would clear his springs also. I learned about the difference right after I bought Darth, the inspector showed me the difference in the width, the station had a 1986 F350 cab and chassis wrecker, built in Norfolk, wrecker body by Dynamic Industries, located across the street from the Ford plant. They had some sort of deal set up where I believe the trucks were ordered through a dealer (on paper) but delivered directly to them.

The wrecker rear duals would clear the base of the twin post lift in the inspection bay, Darth's would have run over the anchor bolts. I used to have to pull in from the back, but then back out to avoid running over the anchor bolts.
Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

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Re: My trucks not stock? Gearing concerns...

86-350-460-dually
So it's very probable that my truck originally only had 4 wheels and someone made it a dually?

Would you be concerned about the rear axle, if you were me? Is it stronger or weaker? Because my speedometer is off by 20+mph, are you concerned about the gear ratio?
Adam

1986 F-350, Dually 4WD, C/C with the 460/7.5L
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Re: My trucks not stock? Gearing concerns...

Rembrant
According to your certification label, your truck was built/sold as an "Incomplete Vehicle" and was ordered by or shipped to the Denver CO area.

It is an F350 4x4 cab/chassis truck.
The "F38" is F350 4x4 regular cab cab/chassis truck.
Rear diff was originally a Dana with 4.56 gears.
Engine is 460, and trans is a T-18 4spd.

I don't see any way to identify if it had DRW or not...maybe Gary knows?

If it has a Sterling 10.25 in it now, perhaps it was changed.

I'd see if I could get a look at the data stamp on the rear diff and see if you can figure out what is in it for gears...that might explain the speedo difference.

1994 F150 4x2 Flareside. 5.0 w/MAF, 4R70W, stock.
1984 F150 4X2 Flareside. Mild 302 w/ 5spd. Sold.
1980 F150 4X4 Flareside. 300i6 w/ 5spd. Sold in 2021.
1980 F100 4X2 Flareside. 351w/2bbl w/NP435. Sold in 1995

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Re: My trucks not stock? Gearing concerns...

86-350-460-dually
This is the only stamps I have found on that differential. These are all on the forward side of the differential. Very hard to read.





Adam

1986 F-350, Dually 4WD, C/C with the 460/7.5L
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Re: My trucks not stock? Gearing concerns...

Rembrant
86-350-460-dually wrote
This is the only stamps I have found on that differential. These are all on the forward side of the differential. Very hard to read.
Well, nothing that is cast into the housing will tell you what's inside it. The data tag may have been removed or rusted away.

Are there any tags on the front differential? Or any way to ID it to confirm what gears are in it?

I'm assuming with the 11,000 lb GVWR that this thing had dual rear wheels...but I'm just guessing. There must be a cut off somewhere in that rating where DRW are required. Gary or Lebaron may know...

If the gearing was changed in this thing, then it would have had to be changed both front and rear. Maybe the transmission was changed...or the speedo cable driven gear. There are a couple things that could cause the speedo to be off.

Transmission change...
Gears changed...
Cable driven gear changed...
1994 F150 4x2 Flareside. 5.0 w/MAF, 4R70W, stock.
1984 F150 4X2 Flareside. Mild 302 w/ 5spd. Sold.
1980 F150 4X4 Flareside. 300i6 w/ 5spd. Sold in 2021.
1980 F100 4X2 Flareside. 351w/2bbl w/NP435. Sold in 1995

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Re: My trucks not stock? Gearing concerns...

Rembrant
In reply to this post by 86-350-460-dually
One thing to try...

Jack the rear end up, and then mark the tire and the driveshaft. If the truck still has the factory spec 4.56 gears, then the driveshaft will have to make 4.5 revolutions for one complete rotation of the rear wheels. That should be pretty easy to see.
1994 F150 4x2 Flareside. 5.0 w/MAF, 4R70W, stock.
1984 F150 4X2 Flareside. Mild 302 w/ 5spd. Sold.
1980 F150 4X4 Flareside. 300i6 w/ 5spd. Sold in 2021.
1980 F100 4X2 Flareside. 351w/2bbl w/NP435. Sold in 1995

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Re: My trucks not stock? Gearing concerns...

86-350-460-dually
I could definitely do that truck with the rear end up and check for the rotations, however, my buddy who has all the jack stands is on vacation until next weekend. So that will have to wait til then unfortunately.
Adam

1986 F-350, Dually 4WD, C/C with the 460/7.5L
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Re: My trucks not stock? Gearing concerns...

Nothing Special
This post was updated on .
Generally I think the Sterling is considered an upgrade from the Dana 60.  Not sure if it's a huge difference, but I certainly wouldn't be worried that my truck had a Sterling.

(edit to add that I wasn't thinking clearly when I wrote the following.  Look down a few posts to read something that isn't garbage.)

Without jack stands but with 4WD you can leave the transfer case in 2WD, lock the right front hub and turn the driveshaft by hand while counting the turns on the left axle shaft (look at the U-joint in the steering knuckle).  It's a little harder to count because you are seeing so many caps go by, but put a mark, or some masking tape on one cap and it's not that hard to count.

Because the front diff is almost certainly an open diff, in this test the axle shaft will turn two revs for every turn of the ring gear.  So if it turns 9 times for one driveshaft rev you have 4.56.  If it turns 8.2 times you have 4.10 and if it turns 7 times you have 3.55.  (Those are the stock ratios.  It could also be 3.73 = 7.5 turns or maybe other possibilities too if the gearing isn't stock.)

On the off chance that you have a limited slip or aftermarket locker in the front diff you won't be able to turn the front driveshaft with one hub locked.  In that case unlock the other hub and do the same test, but don't multiply by two.  So 4.5 turns is 4.56, a little over 4 turns is 4.1, about 3.5 turns is 3.55 and so on.

And of course this is assuming that the ratios in the front and rear axles (essentially) match.  But assuming you've used 4WD, then they must match, or else you'd be asking why it feels like your truck is broken when you drive in 4WD
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
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Re: My trucks not stock? Gearing concerns...

Gary Lewis
Administrator
I agree that the Sterling was considered an upgrade to the Dana 60.  And, good thinking on how to figure out the gear ratio.  
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

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Re: My trucks not stock? Gearing concerns...

Ford F834
Administrator
If the truck had a Dana rear with DRW, wouldn’t it be a D70 or D80? I know that the Sterling is a beefier axle, but After seeing what happened with my short yoke version I would hesitate to rank it above a D60 😬.

Bill, are you saying that the later DRW axles for pickup trucks place the inner wheel track directly behind the front wheels? And do you know if DRW ever came in a 3.55 ratio?
SHORT BED 4-DOOR DIESEL: 1986 F350 4x4 under construction-- 7.3 IDIT ZF5+GVOD

STRAIGHT SIX 4X4: 1981 F150 2wd to 4x4-- 300 I6 close ratio diesel T19, hydroboost brakes, Saginaw steering

BIG F: 1995 F-Superduty under construction— converting to 6.9L IDI diesel ZF5+DNE2
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Re: My trucks not stock? Gearing concerns...

Nothing Special
In reply to this post by Nothing Special
It must be too early in the morning.  I was an idiot and no one called me on it.  I had the ratio backwards.  The method was right, but the numbers were all wrong.

Assuming an open diff, lock the right hub, mark the left U-joint and turn the driveshaft by hand.  But count the number of DRIVESHAFT revolutions as the axle makes 2 full revolutions.  And the number of revs will be the ratio.  ~4 1/2 is 4.56, a little over 4 is 4.10, about 3 1/2 is 3.55.

And if it's a limited slip or locker unlock the right hub and count driveshaft revs for 1 turn of the axle.  Again, 4 1/2 = 4.56 etc.

(A Truetrac limited slip will act like an open diff in this test.)
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
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Re: My trucks not stock? Gearing concerns...

Gary Lewis
Administrator
There's a man that takes the blame.  You could have edited your post.  But, instead you took the blame.  
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

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Re: My trucks not stock? Gearing concerns...

85lebaront2
Administrator
In reply to this post by Ford F834
Yes to the tracking and yes to the 3.55 ratio. Darth came with an open 3.55 gear Sterling 10.25" rear, when I redid the rear because of a spun left rear wheel bearing I took the guts from a 3.55 SRW traction lock and put it in an originally 4.10 DRW open housing (4.10 set had water damage to the ring and pinion). I wanted the limited slip 3.55 gear and needed it to have the ABS tone ring for the 1992 up speedometer so I used the innards from the parts truck SRW 3.55 limited slip Sterling and put them in the junkyard 4.10 DRW open Sterling.
Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

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Re: My trucks not stock? Gearing concerns...

86-350-460-dually
Thank you all. I must give this a test to find out.  I personally have been afraid to give it a go in 4wd, because of my fears of breaking things haha.  However, we shall find out shortly. Thanks for all the info.
Adam

1986 F-350, Dually 4WD, C/C with the 460/7.5L
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