TTB gear ratio

[green meanie]

I have a '86 Bronco with 4 wheel drive. The rear is a 9 inch with 3.50 gears, open.

The front is a dana 44 but I have no clue what the gear ratio is. The tag is too rusty to read. The front has manual locking hubs.

So I have a couple of questions:

1) can I determine the ratio by spinning the wheels and counting the revolutions of the wheel versus the output shaft like you would for the rearend?

2) I am building this truck for mud bogging and once I determine the ratio, if it is not a 4.10 (which I doubt it is) I want to change it. Do the gears come out by simply disconnecting the axles and unbolting the 10 bolts on the front of the housing and pulling the assembly out?

Thanks in advance,

Mark

 

[Justshootme84]

If the rear axle is 3.50, the front will be the same ratio. IF either axle is "open" (no factory limited slip, you need to rotate the tires TWO full revolutions to get the right ratio. Easy way to tell if it's open or not - When one tire spins forward, the other spins the opposite direction. With limited slip, both tires turn the same way when you turn one with the tires off the ground. To remove the ring and pin ion from the front is a major job. You will need to pull both axles out first, then unbolt the center chunk. The driver's side axle will come out once the hub, rotor and spindle are removed. On some models, the inner passenger-side axleshaft has a C-clip inside the gears, so it must come out with them. Not easy for one person, since the center and gears weigh close to 100 lbs. Get a HAynes or Chilton's repair manual which will detail the procedure, JSM84

 

[green meanie]

If the rear axle is 3.50, the front will be the same ratio. IF either axle is "open" (no factory limited slip, you need to rotate the tires TWO full revolutions to get the right ratio. Easy way to tell if it's open or not - When one tire spins forward, the other spins the opposite direction. With limited slip, both tires turn the same way when you turn one with the tires off the ground. To remove the ring and pin ion from the front is a major job. You will need to pull both axles out first, then unbolt the center chunk. The driver's side axle will come out once the hub, rotor and spindle are removed. On some models, the inner passenger-side axleshaft has a C-clip inside the gears, so it must come out with them. Not easy for one person, since the center and gears weigh close to 100 lbs. Get a HAynes or Chilton's repair manual which will detail the procedure, JSM84

Thanks!

 

[Broncobill78]

Mark,

Since you already have answers I won't belabor the obvious. Maybe this helps you & maybe it doesn't. To start off with, if your truck runs & drives in 4WD then you can be reasonably sure that the front & rear gear ratios are matched (they're not always *exact* but if you can drive down the road without hopping, and you have a factory 4.10 rear then you can be pretty sure the front is a 4.10 as well or at worst a 4.11'. If it runs & drives in 4WD then the gears are matched or pretty close to it.

If you want to know what your gears are then as described, the easiest way is to mark & turn the driveshaft while observing the tire. It's plain, it's simple and it just doesn't get much easier than that.

If you decide you want/need to change gears, Maybe they'll call me a weenie but to be perfectly honest I let the Ford dudes change my gears. It's just not something I do in the garage. For me, the easiest (read:Cheapest & most painless) way was to grab a 9" center section from the junkyard (cost me $35) and I had them put the gears into *that* on the bench and then swapped center sections at home. Granted it's only a trick you can pull once with the rear end but it saved me some coin so I spread the word. I drove for few paychecks with a 4.11 rear and a 3.50 front and simply had the insight and intelligence to NOT engage the 4WD and goof around (well, OK I did once but it was *heavy* mud and nothing broke but you really shouldn't do stuff like that because it can cost you big money (Big with a capital "B", as in "B"lown transfer case or "B"lown driveshafts or "B"lown transmission and that doesn't even BEGIN to ge into what whe wife will (or won't) do as a result. Please, trust me on this one).

A few weeks later I had the matching 4.10's installed up front. A difference of 0.01 or so is not important enough to make issue with. You may well run into it and spend a sleepless night ot two dealing with it but the bottom line here is that gears come off the shelf unless you want to spend the $$$ for a custom set and the difference between 4.10 & 4.11 is small enough for the combination of backlash, U-joints & flexible lugs to take up the slack.

Hate to belabor the point, I guess the short answer would have been, Yes you can determine ratio by spinning wheels & watching driveshafts but No, it's not as simple as pulling the axles & 10 bolts to change gears (except on the 9" but only with well qualified help). Sorry, but there just aren't any short answers when it comes to gearing.

I have a '86 Bronco with 4 wheel drive. The rear is a 9 inch with 3.50 gears, open.The front is a dana 44 but I have no clue what the gear ratio is. The tag is too rusty to read. The front has manual locking hubs.

So I have a couple of questions:

1) can I determine the ratio by spinning the wheels and counting the revolutions of the wheel versus the output shaft like you would for the rearend?

2) I am building this truck for mud bogging and once I determine the ratio, if it is not a 4.10 (which I doubt it is) I want to change it. Do the gears come out by simply disconnecting the axles and unbolting the 10 bolts on the front of the housing and pulling the assembly out?

Thanks in advance,

Mark

 

[green meanie]

Thanks for the info. I hadn't thought of, and nobody mentioned earlier, the hazard of running different gear ratios between the axles. /emoticons/[email protected] 2x" width="20" height="20" />

Who are the "Ford dudes" that you use to change the gears?

I don't mind doing the work to change the gears and the 9" is pretty straight forward but getting the front end out is a little confusing and will take some extra effort to understand.

Mark

Mark,
Since you already have answers I won't belabor the obvious. Maybe this helps you & maybe it doesn't. To start off with, if your truck runs & drives in 4WD then you can be reasonably sure that the front & rear gear ratios are matched (they're not always *exact* but if you can drive down the road without hopping, and you have a factory 4.10 rear then you can be pretty sure the front is a 4.10 as well or at worst a 4.11'. If it runs & drives in 4WD then the gears are matched or pretty close to it.

If you want to know what your gears are then as described, the easiest way is to mark & turn the driveshaft while observing the tire. It's plain, it's simple and it just doesn't get much easier than that.

If you decide you want/need to change gears, Maybe they'll call me a weenie but to be perfectly honest I let the Ford dudes change my gears. It's just not something I do in the garage. For me, the easiest (read:Cheapest & most painless) way was to grab a 9" center section from the junkyard (cost me $35) and I had them put the gears into *that* on the bench and then swapped center sections at home. Granted it's only a trick you can pull once with the rear end but it saved me some coin so I spread the word. I drove for few paychecks with a 4.11 rear and a 3.50 front and simply had the insight and intelligence to NOT engage the 4WD and goof around (well, OK I did once but it was *heavy* mud and nothing broke but you really shouldn't do stuff like that because it can cost you big money (Big with a capital "B", as in "B"lown transfer case or "B"lown driveshafts or "B"lown transmission and that doesn't even BEGIN to ge into what whe wife will (or won't) do as a result. Please, trust me on this one).

A few weeks later I had the matching 4.10's installed up front. A difference of 0.01 or so is not important enough to make issue with. You may well run into it and spend a sleepless night ot two dealing with it but the bottom line here is that gears come off the shelf unless you want to spend the $$$ for a custom set and the difference between 4.10 & 4.11 is small enough for the combination of backlash, U-joints & flexible lugs to take up the slack.

Hate to belabor the point, I guess the short answer would have been, Yes you can determine ratio by spinning wheels & watching driveshafts but No, it's not as simple as pulling the axles & 10 bolts to change gears (except on the 9" but only with well qualified help). Sorry, but there just aren't any short answers when it comes to gearing.

 

[miesk5]

yo!

as JSM and Bill advised; plus here is Dana-Spicer's Bill of Material Info; note that the Dana 44 has slightly diff ratios that any rear diff...9" or 8.8

1986 Bronco & F-150

BILL OF MATERIAL

DIFF. TYPE RATIO RING - GEAR & PINION KIT - DIFFERENTIAL RIGHT HAND SHAFT ASSY. LEFT HAND SHAFT ASSY. SHAFT & SLIP YOKE ASSY

610261-1 Standard 3.07 707240-3X 706921X 706923X 706925X 72044-1X 71394-1X 72041-1X

610261-2 Standard 3.54 707240-6X 706921X 706923X 706925X 72044-1X 71394-1X 72041-1X

610261-3 Standard 3.50 707240-5X 706921X 706923X 706925X 72044-1X 71394-1X 72041-1X

610262-1 Standard 3.07 707240-3X 706921X 706923X 706925X 72044-1X 71394-1X 72041-1X

610262-2 Trac Lok 3.54 707240-6X 707147X 707148X 706926X 72044-1X 71394-1X 72041-1X

610262-3 Standard 3.54 707240-6X 706921X 706923X 706925X 72044-1X 71394-1X 72041-1X

610262-4 Standard 3.50 707240-5X 706921X 706923X 706925X 72044-1X 71394-1X 72041-1X

610262-5 Trac Lok 3.50 707240-5X 707147X 707148X 706926X 72044-1X 71394-1X 72041-1X

610262-6 Standard 4.09 707240-9X 706945X 706947X 706925X 72044-1X 71394-1X 72041-1X

610262-7 Trac Lok 4.09 707240-9X 707199X 706982X 706926X 72044-1X 71394-1X 72041-1X

this is a 6-8MB files; so it is SLOW to Load even w/fast Cable!!!!!!!!!!!!!