Hey guys! I need to get 3.55 gears in my 1995 3500 4x4 12 valve with the automatic. When I bought the truck, I was told there is 4.11 gears and I can't stand only being able to barely reach 75 and redlining.

So my problem is that I don't know where to start. Try and find a truck at a junkyard? What rear end I have, If gears are interchangeable in the Dana 70 and 80, do I have to bring the carrier as well as the ring and pinion? should I get used or is new the way to go? Etc...

I just have a bunch of questions but it would be awesome if someone could point me in the right direction or inform me on what to expect.

Thanks!!


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1995 Dodge Ram 3500 Dually 4WD | 4" straight pipe to 9" Stack | Cold air intake | 18* Timing | Tuned AFC w/ stock Fuel Plate

 

It is possible to make a 4.10 diff case work with 3.55 r&p and carrier. Move the case savers and it will work, and just drill the holes, the 80 ring gear centers on the hub.
The only two lockers out there for 3.55 in a dana 80 is either ABR air or a tru trac and its limited slip. or just weld ur spider gears together
Dana 30 3.54 & Down
1.800″ 3.73 & Up
2.410″
Dana 44 3.73 & Down
2.090″ 3.92 & Up
2.410″
Dana 60 4.10 & Down
2.225″ 4.56 & Up
2.420″
Dana 70 4.10 & Down
2.215″ 4.56 & Up
2.410″
Dana 80 3.73 & Down
2.135″ 4.10 & Up
2.312″


Dodge uses a hybrid rear axle on the Ram 2500HD and 3500 equipped with the V10 or Cummins diesel engines. This combination uses Dana 70 axles shafts mated to a Dana 80 center section (including the carrier, ring gear, and housing). While the Dana 70 carrier is the same size as the one used in the Dana 80, the Dana 70 carrier is a multipiece design, while the Dana 80 uses a stronger one-piece unit. The Dana 70 and Dana 80 also utilize a different size bolt to retain the ring gear to the carrier. These are serious one-ton axles for heavy duty one-ton trucks and the locker that you use in them has to be heavy duty too - this is not the little LockRight you would see in a Dana 30 - this beefy locker weighs in at a hefty thirteen pounds all by itself.

The bolt in LockRight is an excellent choice for this application. The ARB and Detroit lockers replace the carrier, and on this hybrid application that would require that the ring gear bolt holes be redrilled to fit the larger bolts. The Detroit Locker's reputation for being bulletproof is largely due to the fact that in the smaller semi-floating axles, such as the common Dana 44, they completely replace the carrier with a stronger unit. On the full floating axles such as the D70/80 Hybrid this isn't necessary because the axle shafts aren't likely to deflect and cause the locker to missalign and break. If you look at a Detroit Locker for a GM 14-bolt, you'll notice that it isn't a full carrier replacement because it's not needed.

An open differential uses a set of spider gears to allow one tire to spin one way while the other tires spins in the opposite direction. Because the differential is mounted in a rotating carrier, the effect is that one tire is allowed to spin at a slower rate than the other and you can easily go around a turn. This is excellent for on-pavement driving but when there is a difference in traction between the two tires, the power is sent to the one with less traction, causing it to spin. On ice or in mud this can very quickly cause a stuck situation. A limited slip differential (LSD) was developed to attempt to compensate for this; on-road a LSD allows both tires to put the power down more equally, allowing for more traction. It does this through the use of special clutch packs and springs. Off-highway, a limited slip does better than an open differential but when a high traction difference exists, such as when a tire is in the air, you still fail to put the power down and get stuck.

The LockRight is a fully automatic locker, a very reliable design which is still easy to install. The locker stays locked under most situations, but under low-torque application, allows one wheel or the other to be disconnected from the driveshaft, thus allowing for differential action. When enough torque is applied, the locker engages solidly and regardless of the conditions, you keep moving. The locker's advantage greatly increases traction on- and off-highway. The disadvantages are that it can lock and drag tires around a turn, and even allow the rear end to kick out under power, though the last is also true of a limited slip.

To prove the point of durability, the locker was installed into the rear axle of Project Puff, a 98 Dodge 3/4-ton Diesel running 35's and delivering 700 crankshaft ft-lbs of torque. If that's not a torture test of any piece of driveline equipment, I don't know what is.

Installation

Begin by unbolting the anti-sway bar, loosening the differential cover bolts, and popping the cover to allow the axle fluid to drain. Oh, make sure to have a big drain pan -- the rear axle holds almost two gallons! Remove the bolts and cover. Unbolt the axleshafts at the hub flange and pull them out about 6". Make sure to protect the rims from any axle fluid leakage.

Mark the main bearing caps for both side and orientation, then unbolt the bearing caps while supporting the carrier. It may fall right out, or it may take a little prying to get it out. Either way, expect the bearing covers to fall off. This is definitely a two man job because the carrier weighs close to 70 lbs. Mark the ring gear and carrier so that you can realign everything, and then unbolt the ring gear. Use a small punch to push out the roll pin and remove the cross pin. Rotate the spider gears until you can remove the top and bottom gears. Then remove the sidegears, being sure to retain the thrust washers for later use.


After removing the axle retaining bolts, the axle should slide out easily.

Notice the factory mark on the ring gear, not bad for almost 90,000 miles.

Once you take the carrier out, drop the ring gear, roll pin, and cross pin.


Replace the thrust washers from the side gears on each of the couplers and install them in the carrier.

Apply a dab of grease to the holes and install the shear pins per the supplied instructions.

Insert the retaining rings into the drivers, then install the drivers supported by the rings.


Slide the shear pins over and insert the springs.

Reinstall the crosspin, shear pin, ring gear and reassemble the axle.


Install the thrust washers on the locker's couplers and install the couplers into the carrier. Apply a dab of grease to the holes in the drivers and insert the shear pins. Place the rings into the drivers and use them to hold the driver engaged to the coupler. Use a small flathead screwdriver to slide the pins over. Install the springs inside each other and install them through the side holes. Use the same flathead screwdriver to make sure the springs have seated themselves into the grooves. Rotate the entire locker and insert the crosspin being careful to make sure the roll pin's holes line up. Gently tap the roll pin into place. Bolt the ring gear back on, carefully observing the alignment marks made previously. Now would be a good time to clean any left over silicone sealant from the face of the housing and diff cover. Reinstall the taper bearing covers and slide the carrier back into the axle housing. Reinstall the bearing caps. Slide on of the axles into place and rotate the whole assembly until the axle retaining bolt holes line up. Bolt the axle back on. Slide the other axle in. It may be necessary to use a jack to lift a wheel into the air at this time to rotate it until the holes in the hub face line up. Bolt everything back down. Make sure to use plenty of Loctite on the ring gear, bearing cap, and axle retaining bolts. Perform the locker inspection per the supplied instructions. Run a bead of silicone on the differential cover and bolt the cover back on. Let the silicone set up for 15 minutes and then add axle fluid. From the two gallons I purchased for the procedure, I had one pint left over after all was said and done.



Final analysis

Driving with the locker installed is somewhat different than any other setup. The truck tends to surge coming around turns more because the inside tire is driven rather than the outside one in turns. Under moderate throttle, the locker engages coming around turns so you can feel a tire being dragged. You can also feel some slack as the truck is launched when the locker engages both axleshafts. While coasting in neutral and turning, there is a slight amount of drag initially until the locker disengages in both directions as well. The unit does however have many redeeming values. Traction is greatly increased off-highway and under dry conditions. While accelerating under full throttle with the open differential, the truck would scratch the tires with a hard shift to fourth gear; this is no longer the case. Under hard acceleration, there is significantly less wheel slippage than before, allowing use of more throttle, resulting in better overall acceleration. Off-highway, the vehicle tends to slide into a straight line up a soft hill -- but other than that, two wheel drive is considerably more usable off-highway and four wheel drive gets you through more obstacles more easily.



After removing the axle retaining bolts, the axle should slide out easily.

Notice the factory mark on the ring gear, not bad for almost 90,000 miles.

Once you take the carrier out, drop the ring gear, roll pin, and cross pin.


Replace the thrust washers from the side gears on each of the couplers and install them in the carrier.

Apply a dab of grease to the holes and install the shear pins per the supplied instructions.

Insert the retaining rings into the drivers, then install the drivers supported by the rings.


Slide the shear pins over and insert the springs.

Reinstall the crosspin, shear pin, ring gear and reassemble the axle.