rear pinion angle? and axle vin#s to ratio.

[djshnizle]

I lifted my 79 4 inches with the shackle flip and my pinion is angled up about 15 degrees give or take... what should it be set at? should I remove those leveling blocks? I gotta take the rear off anyways because I came to find out my ratios are different after I finally got my front driveline built. which brings me to my next question. I need to find out what my front axle ratio is as well as what I need for the rear. What ratio would be recommended for running 40 inch tires? I was thinking 4.56 but wouldnt I need to get bigger cases?

 

[miesk5]

I lifted my 79 4 inches with the shackle flip and my pinion is angled up about 15 degrees give or take... what should it be set at? should I remove those leveling blocks? I gotta take the rear off anyways because I came to find out my ratios are different after I finally got my front driveline built. which brings me to my next question. I need to find out what my front axle ratio is as well as what I need for the rear. What ratio would be recommended for running 40 inch tires? I was thinking 4.56 but wouldnt I need to get bigger cases?

yo D!

Glad you got over here from the other Bronco Forum!

What tranny do you have? Is it going to be a daily driver? or just off-road,, or mudding?..etc.

Gear ratio ~ 5:13 for the 40" tires for highway driving & overall MPG; see this chart and remember what they cite "...If you have an automatic transmission your RPM will higher due to slippage in the transmission and the torque converter. With an overdrive transmission your RPM in overdrive will be 15% to 30% less than indicated...."

Case?.. mean going to a Dana 60?

Front to rear axle ratios should be within a couple percent, about 3% according to the factory; Ford does this mainly for driveability; but most people use same ratio for front & rear when re-gearing..

Front Axle Ratio (orig is a Dana 44 straight axle - also called a SAS, Solid Axles Suspension) - is there still a tag on it? or see this article and diagram of the Bill of Material (BoM) #. etc. location on the 44 by Mr. N

in the other Bronco Forum, I think you mentioned that you had a rear axle wrap problem? if so, ate the springs soft or worn out?

bbl.. have to work

others have more current info...on 40" inchers and what they have done...we didn't go that far in our ex 78

 

[Yardape]

I would go with 4.88 or 5.13 for 40's. Your front should be a D44 with around 3.50 gears.

 

[djshnizle]

I have found a lot of helpful information on this one... thanks for referring me! I will be driving it to the trails, thats all the road use it will see... I am running a 460 with an NP 435 and I believe a 205 t-case... I got it as a trade for my old toyota about a year ago, and like it alot more, but the previous owner did alot of janky things to make it work. such as the axles having different ratios ... and the motor mount not being bolted up, and long tube headers instead of shortys (they didnt clear the drive line) all of which I fixed. The only code I found on the front was casted on the bottom of the pinion housing (sorry not Case) it says 072. the rear axle had a tag and lots of numbers, the tag had the codes WDM-BR 7AA

759 385A

There was also a casting on the top of the housing 638 and the bottom 36

The rear axle has had terrible wheel hop since I got it, I think the previous owner ran it for awhile in four wheel drive with different ratios because it has about 10 degrees of play in the rear axle shaft. now it makes mean noises. ha ha ha. I am considering buying a used axle to hold me over until I can afford new gears, thats why I ask what would be optimum for running large tires... so the question that rises is what are the biggest gears I can fit into the stock housing and what machining would be required to fit 5.13s if any? Oh, The rear springs feel pretty good actually, with that shackle flip bolted to the factory mounts it sits at a rake so they arent sagging, I dont think they feel very soft either because they dont drive too bad as it is and I dont have shocks on the back right now. still pretty stiff. a little bouncy, but thats normal from my experience...

 

[miesk5]

Sorry for the delay; I know a few have re-geared in both the Dana 44 and 9" w 5:13's

for 37 x 12.50 R 15's

Some may suggest swapping Dana 44 to a 60

as for that 072 number.. was it where the diagram here show Ratio Tag?

 

[djshnizle]

Sorry for the delay; I know a few have re-geared in both the Dana 44 and 9" w 5:13'sfor 37 x 12.50 R 15's

Some may suggest swapping Dana 44 to a 60

as for that 072 number.. was it where the diagram here show Ratio Tag?

I guess the 072 is just a factory casting number that doesnt mean anything... I crawled under there again yesterday and pulled the cover off to find the tag in between the cover and housing. imagine that... 3.50s are the front, and I screwed up on the rear tag... where I wrote 759 it really had a 2.75 the 2 was squished under a bolt /emoticons/[email protected] 2x" width="20" height="20" /> 2.75s in the rear so I should have wrote 2.75 9. freeway gears. hmmmm. Now I gotta take the shaft out and count the splines. as far as the D60 goes, would I have to narrow the passenger axle tube? I intend on doing it when I get the cash but I when I do I want to change over to a 4 link setup...

 

[Justshootme84]

The stock rear Ford 9" on the 78/79 Bronco will have 31 spline axleshafts. On my 78 Bronco, I'm running 38" tires with 4.88 gears on the NP435 4-spd and NP205 t-case. That's a really good ratio that I like in 4-Lo first or second gear.

The previous owner also had problems with axle wrap and busting driveshaft or rear pinion yokes. The rear driveshaft should point nearly straight into the axle pinion yoke. Thru trial and errror using different combos of blocks and springs, he finally found an AAL (add-a-leaf) worked out under the stock springs.

As a replacement axle, consider going to a GM 14-bolt rear. My 78 has a Currie Nodular center section with a full spool, but I'd hate to price that nowadays. The 14-bolts usually run about $150-$200 used, and would hold up better to those bigger tires. JSM84

 

[djshnizle]

what rigs can I find a 14 bolt under? I might just do that, sounds like it would save alot of pain... I dont even have the tires yet, its been a toss up between 38s or 40s how much lift do you have on yours? Mine only has a cage 4 inch. I will be hacking all excess body metal though. as far as the rear pinion angle its perfect with the factory blocks and the shackle flip, I was just worried about keeping the diff lubricated. I was looking at Curries stuff, your definitely right about pricing... ouch. I might get a good deal on a 79 f150 everything is in great running order, if I do I wont be able to pass it up and I will just use its rear axle for the time being until I can get a D60 and a good rear then I would turn the truck into my towing and part hauler! What do you think about the D70 rear? I found one for 350 at a junk yard in pretty good shape... I am kinda worried about the weight. anywho, looks like I got alot of searching to do... thanks for the help.

 

[Justshootme84]

The GM 14-bolt can be found under the 1-ton Chevy/ GMC trucks, and I've even seen them under some of the GM vans. Best place to find one is the local Craig's list or 4x4 club. The spring perches need to be moved to fit the Bronco frame. The benefits of the 14-bolt is that it's a full-floating axle, has better ground clearance at the pumpkin than the Dana70, and lockers are readily available. It does have an 8-lug bolt pattern, and huge rear drums for the brakes. you'll also have a better shot at matching gear ratios with your front axle.

I think now I get what ytou're saying about the "pinion angle", in that the yoke is pointing up 15-20 degrees? That's not enoughg to cause **** problems.

Other than the rear AAL, the 78 Bronco is on stock suspension, with 3" cut out of the front fenders and the forward edge trimmed on the rear quarters.

 

[djshnizle]

The GM 14-bolt can be found under the 1-ton Chevy/ GMC trucks, and I've even seen them under some of the GM vans. Best place to find one is the local Craig's list or 4x4 club. The spring perches need to be moved to fit the Bronco frame. The benefits of the 14-bolt is that it's a full-floating axle, has better ground clearance at the pumpkin than the Dana70, and lockers are readily available. It does have an 8-lug bolt pattern, and huge rear drums for the brakes. you'll also have a better shot at matching gear ratios with your front axle.
I think now I get what ytou're saying about the "pinion angle", in that the yoke is pointing up 15-20 degrees? That's not enoughg to cause **** problems.

Other than the rear AAL, the 78 Bronco is on stock suspension, with 3" cut out of the front fenders and the forward edge trimmed on the rear quarters.

will I have issues tryin to depress bigger wheel cylinders with a stock master cylinder? Bigger would be nice seeing as I couldnt stop the thing to save the world with 32s... you clear those tires all the way? any rubbage? That would sell me on a set of 40s. have you ever had problems with the BB 9 inch? Full floaters would be great, the 9 inches are pretty easy to change out though... and more abundant in my situation. does the 14-bolt have the same lug pattern as the ford D60 front? Sorry to bombard with so many questions, but decision making time is coming fast. gotta be ready for memorial day!