I have a 51 Ford coupe with a 289 and a 3 speed with a 1:1 3rd gear. I have an 8" rear axle with a 4:1 ratio approx. I need to change to a 3:1 or so axle, I hear the Granada is a perfect fit and I was checking to see if anyone used a Monarch instead and if they know what the gearing is on that and if there is more than one gearing axle that was available for those models. I try to look online for info on other sites and you get so much B.S. instead of what you need. I know where there is a Monarch so that is why I am asking. Thanks for any help, Bill
Monarch is the same as Granada......size wise. Most common ratio is 2.79, but I think there may a few others. The width you use on a shoebox is kind of critical, as the wheel housings are not very wide........so it becomes a balance of wheel width and offsets, the tire sidewall width and the axle width. Not rocket science.......just careful use of a tape measure. Ray
With a non-overdrive transmission and for normal street use it will be fine. The standard ratio was 2.79 for most V8 applications Ray
I think 2.79 was a fuel mileage diff back then. Many of them had around 2.49 or so, too. Not too perky. I had a 5.0 / 220 hp with a 3.08 diff and C-4 in my 37 sedan. Also not too perky, but I got 20+ mpg on the interstate with a 600cfm carb. If you are just going on short trips, around town. I'd get a 3.50 diff, at least. Gary
Granadas and Monarchs are mechanically identical, just a few cosmetic differences. Same drivetrain options on both. The 8" rears are plenty strong enough for normal driving, find a 9" if you want to go racing. Probably 90% or more of Granadas/ Monarchs had automatic transmissions, and they came with D78 or E78x14 tires, so as others have noted, most were geared high.
Welp...I'd watch the width on a granada housing..I used a Maverick under my 49 because it was the closest to the original rear axle. I was able to use a 6 inch wheel with zero offfset with a fairly narrow tire and I still had to trim the lip a little...on gearing: 289's are short stroke engines and have little low RPM torque. I'd go with a 3.00 -3.73 gear with a 28 inch tire. Anything higher geared will be low on power in town and off the line. Also, the engine won't be up to it's most efficent RPM on the road..the 289 should be at 3000 rpm at cruise or close to it. I once had a 49 ford F-1 with a 289 and a 4.27 rear gear. Now, that was a little too low geared on the hiway and I lived 35 miles out of town. The 4000 rpm cruising never caused a problem but the truck was noisy and used a fair amount of gas for a stock 289 on the hiway...
This might give you a bit of comparison as far as measurements go. http://www.carnut.com/specs/rear.html The shoebox Fords seem to be one of the hardest cars to fit wheels, tires or rear ends under when you start changing. Everything has to be right or it doesn't fit.
what is wrong with the 8" rearend that you have? if width is OK, basic job to change 3RD member on them and plenty availble.
My guess is that the OP DOESN'T in fact have an 8" rear end, not what is generally meant by that term anyway, but likely the original rear end. Could be wrong about that of course...........but suspect that is the case. Ray
It is an 8 inch not original rear end. It is also a posi so I hear that makes it more difficult to change the gears, is that true? Shoeboxford.com claims the Granada is almost a perfect fit si it seems the easiest and best solution other than I put all new brakes in the rear end.
Being a TracLoc doesn't make changing gearing any harder but while you are in there, check the clutch packs (then, it gets a tad more interesting).
If in fact you have an 8", there is an assortment of gears for them. You don't need to disassemble the posi trac part to change gears. You are changing the pinon and the ring gear. I've had numerous 289's. My thought is either a 3.25 or a 3.50 gear. Some Monarchs came with 8" rears. Do you have a reason to change out the whole diff.?
OK, so you have an 8"............plenty of used ones around from which to get a carrier (third member. "pumpkin" etc.) assembly and just swap out the current for the replacement.......unless you prefer to keep the limited slip diff. Ford 8" & 9" are fairly easy to set up if you do decide to change the gearset. The only shims are between the pinion carrier and the main housing to set pinion depth. Backlash is set by threaded adjusters on either side of the carrier bearings. Ray
I have never done a rear axle gear change and it seems alot easier to change the whole thing instead of the gears on the 8 inch. Cheaper maybe also? I am not afraid to try anything but I am trying to find the best choice and of course price also. This site has so many talented individuals and opens your eyes to so many alternatives.
Well, the easiest way to change gears would be to remove the 'third member' aka gear carrier assembly and swap in another carrier with the gears you want. That does require pulling the driveshaft, drums and axles, removing the nuts from the carrier housing and prying it out the third member. On 'unmolested' rear ends there are small copper sealing washers under the nuts that can be a pain. I chisel them in two to remove them. Otherwise the carrier doesn't want to move as the copper is crushed into the stud. After that, just clean up the mating surfaces, install a new gasket, install the new third member, axles and drums and you're good to go. It may be worth replacing the axles seals (inside the outer ends of the axle housing) but if they weren't leaking you could leave them alone. If you do change the whole rear end assembly you may inherit some problems you don't currently have with the aforementioned seals, brakes, axle bearings etc. Sometimes the devil we know is better than the devil we don't. Ray
Another option for ya' if you can find one, is the similiar years of the Lincoln Versailles (Lincoln's version of the Granada/Monarch). Many of the Versailles came with rear discs (though not very traditional/HAMB'y...), if that's what else you're looking for. I think Hnstray is correct about you probably just changing the gearing if the 3rd member you install doesn't work for you (sorry). For the record, I worked in a few different Ford and Lincoln/Merc dealerships back in the late 70's when those cars were new and I don't remember seeing any Granada/Monarch/Versailles that had any other trans out there besides an auto (while I'm sure they made one somewhere...), so trying to find a rear with a "better" gearing for your 3 speed is probably gonna be a gamble.
"Well, the easiest way to change gears would be to remove the 'third member' aka gear carrier assembly and swap in another carrier with the gears you want." This is indeed much easier than changing out the whole rear axle. You can do it in a afternoon even if you've never done it before.
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