axle isues - D53 and 4.27 front vs 4.09 rear

[hzl6cm]

Tonight I was trying to determine if the rear differential on my "new" '63 J-200 (vin # 2406B 10571) was a D53 or D44 and it looks like I need help on a few things. I found lots of numbers on the rear differential but not the correct ones, however, it looks like it is a little larger than the front differential. While both have 10 bolt covers, the front cover is a little "pointed" on the top and bottom while the rear cover is flat on the top and bottom. Also, the rear diff has 4 gussets between the housing and axle tube while the front has three.

Of more imediate concern, the tag on the rear diff says 45:11 4.09 while the front one says 47:11 4.427. I think that I read that the 4.27 diff is standard for this truck so it appears that the rear axle was swapped out - plus the rear shocks are unbolted. Since the pinion gears are the same, can I find a 45 tooth ring gear for the front axle (a D44 I think) and just replace the 47 tooth gear?

Thanks.

Kevin

[joe]

Kevin, yes your "B" model truck should have a D53 rear w/4.27 gears (opt 4.88's) in it but after 40 years it may well have been swapped out for a later D53 or even a D60-2 semi-floater.
I'll email you a pic of where to look for the model number besides on the gusset. I'd pop the cover off the rear and count the teeth on the ring gear just to be sure it really is a 45 tooth and 4.09's. On old rigs I'm always leery of bolt-on tags...
Hopefully you won't have to swap the gear because you have to set up the differential again afterward and it's a bit tricky if you haven't done one and you'll need a few special tools like a dial indicator, mag base for it. A shop will ding you about $300 for the labor alone. This is assuming you can even find a ring gear for a D53(unlikely) or even a D60-2(odds are better but not good). May find a used R&P set though. There should also be a build date stamped into the ring gear so if it's a later date than your truck you know at least that's been swapped. I don't have either a D53 or D60-2 around anymore to take a picture of. Maybe my email will help...?

[hzl6cm]

Joe, thanks that does help. You mention a D60, there was what looked like a small tag cast (it looked like two screw heads and a small tag but appeared to be part of the casting) in to the lower right (looking at it from the drive shaft side) gusset with what looked like an inside out "60" on it (like it would have read correctly from the other side of the tag). The numbers looked to be about a quarter of an inch high - is that what they should look like?

Kevin

[Tad]

I have 19 spline Dana 44 ring and pinion for sale with 4.09 gearing. It would be a drop in for your front I think.
Just a thought, long way to MO.

[ August 10, 2004, 09:04 PM: Message edited by: tadsal ]

[joe]

If it's the semi-floater D60 it's actually a D60-2 model and will have 60-2 cast into the top of the gusset nearest the axle tube. If it just has 60 cast into it it should be the full-floater D60 with the large hubs sticking out through the center of the wheels. It'll have 8 lug wheels too instead of 5 hole. The semi-floater will be flat/flush behind the rims.

[hzl6cm]

Joe has given me some good info to look in to tonight when I get home - thanks for the diagram of where the markings should be. Plus I want to jack up a wheel on each end, mark it and the ajacent drive shaft and then rotate it to see if the ring and pinion that are installed match what is on the tags. If they do match the tags, what is everybodies opinion on what axle ration I should shoot for, 4.27 or 4.09? The truck has the original 6 banger and a 3-speed transmission (so no granny low). I plan to do some mild off roading with it (nothing too radiacal). The 4.09 would work better on the highway, while the 4.27 would give me better gearing for off road use. Thanks.

[joe]

It's gonna be tough pinning down the ratio by spinning a tire. Those ratios are really close. If you jack up both rear wheels you can just spin one tire and count the drive shaft revs directly or just one tire and then multiply by two but in any case with old worn(sloppy) drive train components it's going to be tough to judge did the shaft spin 4 times and maybe an 1/8 more(close to 4.09) or a 1/4 more(close to 4.27's). When you do it mark a reference mark not just on the tire but also on the body so you get "exactly" one spin of the tire. Don't start counting that one spin till you get all the slop out of the axle either. This is a good and easy method for trying to see if you had say 3.54's (about 3-1/2 spins) or 4.10's(little over 4 spins) but between 4.10 and 4.27 I don't think you'll feel confident with the results. I would pull the diff cover off and count the teeth. 99.9% chance you'll need to change out the old gear lube anyway.

[hzl6cm]

You are right, that is probably the best way. I've got a foaur post lift I can put it on if I move the corvette out of the way first (it is up there hiding from the mice). That way I would know for sure.

When I've done the rotating the tire method before I have rotated it 10 times then devided the drive shaft rotations by 5 to get the ratio - by doing 10 times (instead of the normal 2 times where the gear ratio is the number of times the driveshaft rotates)it helps elimate errors from driveline slop etc.

Kevin

[tgreese]

If you take the covers off, before you start counting teeth, the tooth ratio (ie 47:11) should be stamped into the side of the ring gear.

[hzl6cm]

The rear axle is a Dana 53 with a 4.09 ratio - thanks Joe for the diagram showing where the casting number should be - it was on top (at the spot marked "X") acword to get to while laying on the ground. I ended up measuring the ration by jacking up one wheel, laying underneath, marking the inside of the tire by the lower spring leaf (which gave me a real good reference point), taking the slack out of the driveline, marking the pinion flange and the diff housing next to it (which again gave me a good reference point), turning tire slowly exactly two revolutions and counting the revolutions of my mark on the pinion flange - it was definitely 4.09 since it would have had to rotate over an inch more to get to 4.27 - which matches what is on the tag - unfortunately. I guess that I ought to check the front diff to make sure that it is 4.27 but it probably is since that is what it is supposed to be - looks like I wil be changing out the front ring and pinion so that both will be 4.09.

Kevin

[Tad]

I got your email and honestly I think it's just as easy ($5 gasket and some gear oil) to pop the diff cover and find the stampings on the ring gear.
Anywho, keep me posted, looks like this set can sit here for about another week until it's in my way.

[hzl6cm]

I got the jeep up on the lift (lots of fun hooking it up to my '49 Chevy wrecker since there are bumpers on the Jeep and then backing it around a 90 degree corner to out it on the lift (fuzzy 40 year old mirrors on the wrecker and no brakes again - but better than pushing!) and pulled the diff covers:

Front: Danna 44, 11-19-62 47 11 stamped on the ring gear so it is a 4.27 like the tag says.

Rear: Dana 53, 7-17-62 45 11 stamped on the ring gear so it is a 4.09 like the tag says.

Both date codes fall pretty much where they should for the truck which was probably built right towards the end of '62. To further complicate things it has 7 - 16 tires on the front and 7.50 - 16 tires on the rear. The front tires measure 14 inches from the floor to the center of the hub (eyeballing the center) while the rears measure 14 1/2 inches from the floor to the center of the hub. It looks to me that if I swap the front and rear tires (so the larger tires are on the 4.27 axle and the smaller ones are on the 4.09 axle) that my total ratio (including differential and tires) would be less than 1 percent different between the front and the rear, which should be okay since I would only use 4wd on slick surfaces. What do you think? It already sits pretty high in the bag with the 6600 lb GVW rear springs and even with swapping the tires it will still sit higher in the back so it will look okay.

On a related note, is it normal for the rear drive shaft to be angled several inches towards the passenger side as it goes back? It almost looks like it starts on the drivers side of the vehicle center line and goes over several inches towards the passenger side. Most vehicles I have had I thought the drive shaft went straight back.

Thanks!

Kevin

[Tad]

Sounds like you have that gear and tire thing nailed down correctly Kevin.
I'm sure that's was the reasoning in the different tire sizes and it was probably close enough.
The offset on the rear axle exists on all these rigs till we get into the 80's with the narrower gas tanks and the AMC20 and later years.
The D20 versions are offset a bit less than the Qtrac versions IIRC.
I doubt it will be an issue.
Even my '51 Willys truck was off set a bit and there was no tank to clear.

[joe]

Sounds like a plan Kevin. If you're just going to use 4WD on slick surfaces using the slightly larger tires on the 4.27 end will work fine. As Tad mention the shaft angle is normal on all Jeep models prior to 80.

[hzl6cm]

As an added note I punched the numbers in the gear ratio calculator on f-body.org ( http://www.f-body.org/gears/ ) this morning. In this program you inpute tire size or diameter, axle ratio, transmission gear ratios and rpm. The it will out speed in mph for each gear at the rpm you input. I just input 1.0 for third gear (I don't know if that is correct or not but since I was just using the program for comparison purposes it didn't matter) and 3,000 rpm. The for the front axle I input a tire diameter of 29 inches (my 14.5 inches measured from the floor to the axle center line times two) and 4.27 for the axle ratio. For the rear axle I inpute 28 inches and 4.09. For both sets of perameters the program output 61 mph in third gear at 3,000 rpm - you can't get much closer than that! I don't see any reason why it won't work.

Kevin