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Setting up Differentials
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Subject: Re: [RAM] Decode for rear
end id tags
On my 95 and 97 2500s, the diff tags are about 5" long, made of aluminum
and go between two cover bolts. The top 8 digit number is the axle assy
part number. Under that number is the ratio on the left, and then the
"bill of materials" number that is used as an identifier to order
parts from Dana, etc.
Do I need a case spreader to remove the carrier?
From Joe Donnelly: In the old days, Dana put 0.010" to 0.015" preload on the carrier and it was hard to pry out (but I did it many times with pry bars, or by turning the pinion gear after replacing one ring gear bolt with a bolt long enough to hit the housing when the carrier rotated a bit). Now they put only a few thousandths (like 0.003" new which gives zero or even loose when worn in), so removal is easy. Just be prepared--I put a long bolt in the lower carrier cap holes--so it doesn't fall out on the ground once started.
Subject: [RAM] long post on setting diff gears
Attached is a post on setting differential gears. Hope this helps answer Justin's question, and that it is of some general interest. Joe
You need the ring and pinion. They are matched sets. If you aren't familiar with setting them up to the nearest 0.001 inch, it is expensive to change them. If the used gears aren't scuffed, etc., they are OK, but must be set up to your housings. A new gear set from 4 Wheel Parts or other supplier probably will run $150-250. If the dealer does the work it may help in the event of a future warranty claim, but may cost a good bit more to perform.
If you have tall tires, going to shorter ones will help, and be an easier change. The Dodge factory service manual shows how to change gears, but not the "tricks of the trade" to make it easier. Still takes some knowledge and skill. See my article below. I submitted it to Turbo Diesel Register, but it's not published yet.
The principles for Dana's apply pretty much to the corporate rears, too.
Sorry the post ends up so long, but the question is not one with a brief answer.
COMMENTS ON DANA DIFFERENTIALS
Dodge, along with Brands C and F, has used Dana (Spicer) differentials for decades in light trucks where strength and durability are more important than cost.
The Dana 60 (called 248 RBI in 1997 Service Manual) has a 9.75" diameter ring gear, and until recently (such as the front end of Ram 4x4s), used solid shims between the outer bearing's inner race and a shoulder on the pinion stem to adjust the pinion bearing preload. The new 4x4s use a collapsible spacer, a la GM, probably for cheaper (faster) production.
The Dana 70 (267 RBI) has a 10.5" diameter ring gear, and the 80, 11". The carrier (open or posi) side bearings are the same on 60s and 70s, with an outer race outside diameter of 3.813" and width of 0.795". The individual tapered rollers are about 0.578" long.
The Dana 80 (286 RBI) side bearing measurements are 4.125", 0.965", and 0.796", respectively. Note that I took these measurements with a vernier caliper, so they may not be "perfect". Its substantial increase in bearing size makes the Dana 80 more durable for heavy duty, high torque applications.
The 60-70-80 all have a side bearing inner diameter of about 2.245" and therefore can use the same backlash adjustment shims. The 1997 numbers correspond to the ring gear diameters in millimeters, except for the Dana 80, whose diameter specification is 279.4 mm. Aren't metrics wonderful? RBI means Rear Beam-design Iron.
The Dana 60s and 70s use 1/2 x 20 thread grade 8 ring gear bolts (110-120 ft-lb tightening torque; different year Service Manuals give slightly different numbers, so I am showing numbers that appear to be safe for all years I checked). The 80 uses grade 9 bolts torqued to 200-240 ft-lb. The pinion nut on 80s is also bigger, and takes 440 ft-lb, instead of 250 ft-lb. The Dana 80 4x4 differential takes 5+ quarts of lube (the 4x2 takes about 3-1/2 quarts).
The Dana 80 has slots at the bottom of the side bearing outer race abutments in the housing. These slots at the inside of the axle tubes allow oil in the tubes to drain directly into a trough at the bottom of the "pumpkin" area, bypassing the side bearings. The Dana axles lubricate the bearings and gears by splash, including the outer bearings at the brake hubs. The Dana 80 drainback feature is valuable because it minimizes the contamination of the bearings by rust accumulating in the tubes. Presumably, the rust can accumulate in this trough. Most problems that I have seen in used units can be traced to bearing failure from this contamination. Remember, these bearings are harder than the hubs of hell, but extremely intolerant of dirt. If the bearing surface of the outer race is grayish and pitted, it is trashed. You can be sure the smaller inner race is in even worse shape. If you think bearings are expensive, try replacing the carrier and/or housing too, after the bearing races "spin"!!!
I have not been too happy with most limited slip units. They seem to "lock up" just enough to cause chattering and tire wear, but not enough to help when you really need them. If you can take some extra tire wear, and snapping and banging on corners if you abruptly apply/release power, the most famous, strongest, and most positive (while being user-friendly) "limited slip" carrier may be for you. It is the No-Spin or Detroit Locker, from Tractech. Since our Rams have long wheelbases, the positive locking and unlocking actions do not affect handling and steering nearly as much as on Jeeps and other short vehicles. The Detroit Lockers are available for the 60 and 70 series. They also have one for the 80, but they told me they really make it to supply it "OEM" to Ford for the Super Duty trucks. For that reason, it is suitable only for 4.63 and 5.13 ratios. They make one that will fit the Dodge with its 35 spline axles, but the ring gear mounting surface is about 3/16" too close to the pinion for the Dodge 3.54 and 4.10 ratio gearsets. Tractech told me they plan to make one for Dodge ratios within a year.
The above ring gear mount spacing situation is analogous to the 3-series and 4-series carriers for the 12-bolt Chevy passenger car rear. (If you weren't "into" GM performance cars in the 1960's, this analogy may not help you.) To get higher numerical ratios, the pinion gear has fewer teeth and/or the ring gear has more. As the pinion gear diameter is reduced, the ring gear thickness is increased to compensate, until a point is reached where the manufacturer moves the ring gear mounting surface on the carrier so the ring gear does not have to get very thick for increasingly higher number ratios. This practice of making different carriers is generally used for rear-cover, pressed-tube axles like Dana and GM. Ford 9" and Mopar 8.75" with removable "pigs" use only one carrier ring gear spacing. For examples, truck Dana 44 axle carriers change between 3.73 and 3.92; Dana 60, between 4.10 and 4.56; 12-bolt Chevy passenger car carriers between 3.73 and 3.90.
On snow, you may actually prefer an "open" differential, particularly on side slopes, because any limited slip can tend to make you slide downhill (sideways) as it locks, unlocks, and spins both tires. The No-Spin is not recommended for the front differential of 4x4s, because it must unlock, or spin a tire, for you to turn. This rough action strongly affects steering. Also, if you are a hot-dog who greatly overloads the truck, you may be surprised how easy it is to BEND the axle tubes! This is bad news (housings cost $$$) in any event, and even more so if you have a Detroit Locker, because the dog teeth inside the Locker will shear off if the axles are badly misaligned from a bent housing or from bent axles themselves. These teeth then get into the pinion bearings. Need I say more?
Now for some maintenance suggestions. I make sure the fill level is a bit above the bottom of the plug--for example, fill it when the truck is pointed downhill. Don't 'way overfill it, however. You just want to make sure the axle tubes and outer bearings at the wheels get enough lube. Remember, as with motor oil, half the function is to carry away heat. Whenever I replace a brake seal, I smear a bit of moly wheel bearing grease or moly camshaft lube on the lip and bearing surfaces to help the seal break in without burning up. Change the axle lube occasionally. Depending on the amount of heat (such as, from towing or very high speeds) and the ambient humidity, good intervals could be anywhere from 12,000 to 36,000 miles. While you have the cover off, check for metal in the oil, and pull the left side bearing cap (that side gets more force toward the cap). Look for signs that the outer bearing race is "working" or turning (wear and polishing on the portion of the machined surface inside the cap where the race touched it). If so, there is probably metal in the bearing, and if not corrected, the added friction on the bearing will force the outer race to turn in the housing until it develops clearance (instead of the designed-in light press fit), and serious failure can result.
If you are familiar with working on rear axles, you can check the preload on the side bearings, too. The Dana 80 on my '95 was improperly assembled by the factory with zero preload. Make sure you re-torque the side bearing cap to specs, in stages, between the two bolts. About 80-85 ft-lb is generally correct for Dana differential side caps. Unfortunately, if the differential is ignored, preload is missing, or dirt/rust get into the bearings, you generally won't have a failure until well after the warranty is over. Also, you won't believe the costs you can incur for such failures! If you get water in through the breather (like, from going through deep water), change the lube immediately.
For the more advanced owner, it is quite possible to set up a differential correctly in your driveway. REMEMBER TO KEEP IT (the diff!) CLEAN!!! Pinion depth can be set by comparing the etched numbers on the head of the new pinion to those on the original pinion and changing shims per factory Service Manual. (This works easiest if the pinions are OEM, not aftermarket; aftermarket pinions may have only the absolute depth setting, not the relative setting that makes comparison easier). Never match a ring gear to a different pinion--they are run in together at the factory, and then in service. They have "serial numbers" etched on them to indicate they are mated together. By the way, gear ratios never have the ring gear teeth an even multiple of the number of pinion teeth, because each tooth of one gear should mesh each tooth of the other over time to avoid uneven wear patterns.
Check the pinion depth with an indicator compound such as yellow lead that is brushed onto several of the ring gear teeth, after you properly set the backlash of the ring gear. Service Manuals generally don't tell you one key fact--as you rotate the ring gear or the pinion by hand, you will not get much load on the gear tooth surfaces. Try to get some load--actually, by manual turning you will only get "firm" contact--by retarding the rotation of the driven part, but do not seek the "book" ideal contact pattern. That pattern is for light in use load by engine vs. truck weight! Under manual rotation, the drive side pattern of the ring gear teeth in the yellow lead should be to the inside of the ring gear, but should not run off the inside edge. Coast pattern is closer to centered under manual rotation, when pinion depth and backlash are correct. Under real-world load, the drive pattern will spread toward the outside of the ring gear, as load pressure tries to force the gears apart. So the load contact pattern doesn't run off the outside edge under load, you must set the very light (manually applied) load pattern to the inside half of the tooth.
It helps to have a dial indicator, but I have set backlash by first setting it to zero, with enough shims to completely fill the space but give zero preload on the side bearings. Then I move 0.010" of shim from the ring gear side to get 0.005" backlash, and add 0.006" to each side for preload. I have made up "trial bearings" from old bearings by honing the inside for a slip fit on the carrier. (Take them to your automotive machine shop where they have connecting rod hones, or be very patient with a flex hone--it will take about an hour or so with the flex hone.) Dodge--Mopar Performance--can sell you a kit with shims for the Dana 60-70, and you can supplement them with more shims and different thickness' from taking apart differentials and/or begging at a shop that specializes in differential repair. You need three sizes--side bearing, pinion preload (or the collapsible spacer on front axles of newer 4x4s), and pinion depth. Avoid bent, crunched shims because it will be too hard to press them flat while setting up the differential. In their infinite wisdom, Dana puts the side bearing shims behind the bearings, instead of between the outer race and the housing, as GM does. Oh, well; it makes the trial bearings essential. The pinion depth shims are behind the outer race of the inner bearing.
After all this, it should be clear (I hope) that changing the carrier, such as installing a Detroit Locker, entails resetting the carrier bearing (side bearing) shims to obtain the correct preload and backlash. The changes in shimming are to compensate for different relative positions of the ring gear to the bearings, and different distances between the bearings. These differences are generally only a few thousandths of an inch. Pinion depth need not be adjusted unless it the pinion gear is changed. Note that the roller bearings are manufactured to very close tolerances, so replacing them should not require shim thickness changes.
If the pinion seal is leaking, or you have a throttle-sensitive vibration through the driveline, you may have bad pinion bearings. For the Dana axles with solid shims setting pinion bearing preload, changing the seal and bearings is simplified. If you have the collapsible spacer, you will need to torque down a new one carefully. Turn the pinion frequently so the rollers will seat properly. GM offered a shim about 0.010" thick to put on one end of the collapsible spacer to save it on reassembling the differential. It also saved collapsing the new one a seemingly interminable amount. I don't know if Dana offers such a shim, or if you could get away with using one that happened to fit. Presumably, you could retrofit the earlier type gearset with the shoulder on the pinion stem for solid shims, if you are changing ratios in a 4x4 and found used gears for the front axle. Again, use a little moly (molybdenum disulfide) lube on the seal lips and the surface they ride on.
The factory uses coated steel gaskets between the axle shafts and the brake hubs. Replacement gaskets are often fiber. Torque causes the axles to work on the mounting surfaces because the fiber gasket acts as a "sponge" without sufficient shear strength, and leaks often occur. I use no gasket, just a film of red RTV sealer after cleaning and degreasing the surfaces.
You may remember that many years ago bevel and spiral bevel gear types used in antique cars did not require this careful setting of clearances and spacing. It should be pointed out that hypoid gears (such as used by the Danas and other modern differentials) are stronger and allow a lower floor pan because the pinion gear is well below the centerline of the ring gear. If you look carefully, you will note that the Dana 60 (and 12-bolt Chevy) pinion is closer to the ring gear centerline than the Ford 9" ring gear differential. The Ford is renowned by drag racers for great strength--torque capacity greater than the Dana 60 with proper beefing up--with moderate weight about like that of the 12-bolt Chevy. However, the 9" Ford's settings are very critical, and gear friction tends to be greater because of the Ford's greater hypoid angle.
If this sounds like a foreign language, start by reading the Dodge Service Manual for your year truck, and work on someone else's truck first to learn how (but not mine!). If you suffer trepidation changing your engine oil, just be aware of the above information to "debunk" the stories your mechanic may tell you. The Dodge Service Manual costs $100 for 1997, which makes the 1995 manual a great deal at $50!
If you do your own work, 4 Wheel Parts of Gardena, CA (800- 421-1050) has given me good prices for Timken bearings, etc. for my Danas. Note that the Dana 80 may not come with Timken bearings; my 1995 had side bearings labeled Japan WN NTN, and 4 Wheel Parts sent me Koyo replacements. The side bearings and outer races (cups) for Dana 60-70s are 387A and 382S, respectively. For the Dana 80, they are 469 and 453X.
Subject: DrDonnelly's Dana writeup
From: "CRAIG C. SCHOLL" <SCHOLL@stic.net>
Very informative article. The part about changing the "crush" sleeve or collapsable sleeve when changing the pinion seal is not always necessary. Their was a TSB a while back covering leaking pinion seals. Although my 1997 is under warranty, I chose to spend the money and change it myself. You need to remove the tires and brake drums and drop the driveshaft. Use an inch pound torque wrench (dial or beam, a clicker won't work) to measure the rotational torque. Write this measurement down. Pull the yoke (this is not easy, it's got somewhere around 185ft.-lbs. of torque holding it) and remove the seal. Reassemble, and retorque to your previous number (sneak up on it) and then add 5 in.-lbs. (don't quote me on this number, read your service manual!). This is much easier than pulling the carrier and much quicker, believe me! Why did I do it myself? I've seen the way the tech's do it, they are on the clock, so they simply reimpact the yoke nut down without taking pre or post rotational torque measurements. If anyone needs the factory procedure for replacing their leaking pinion seal, you can e-mail me direct.
Subject: Re: DrDonnelly's Dana writeup
Craig's procedure to avoid changing the crush sleeve often works. However, let me elaborate so the installer will understand better whether this short-cut is working properly on that particular differential.
The spacing between the front and rear pinion bearings must be set exactly so the bearing preload is correct. Ideally, this setting will be within 0.001" of "perfect". A solid spacer may be used (they are available aftermaket for some differentials, and were used OEM, for example, by Ford in the 9" nodular pumpkins). The same concept is involved with the Dana procedure of putting shims on a shoulder of the pinion shaft. This method precisely sets the inter-bearing distance. Because replacement bearings are made very accurately, the new bearings will be properly preloaded when you reuse the solid spacer or shims.
The crush sleeve method is a factory short-cut that allows assembling the differential once and getting it right by simply tightening the pinion nut until the preload is correct. The problem with replacing the bearings or the pinion seal and reusing the collapsible spacer involves accuracy and the ability to re-tighten the pinion nut exactly right, and to get just the correct amount of preload (as Craig noted, you put just a bit more preload on the bearings, hopefully to collapse the spacer just a bit more.) However, if parts tolerances are working against you, the preload may not actually be tightening the bearings against the used spacer. Perhaps more often, the desired preload is exceeded, and you should not just back off a little because again the spacer is not doing anything to hold the bearings. The bearings' inner races are a slip-fit on the pinion shaft, and you don't want them to "cock" from being left unsupported by a spacer.
Drag racers got around the spacer for some time by using Loctite between the inner races and the pinion shaft. I don't know if this short-cut is still popular, but it was intended to be amenable for use on very low-mileage applications where gear changes were frequent. I do know a company is selling solid spacers for the 12 bolt Chevy, etc. to replace the factory collapsible spacer. The most positive, solid, and high-quality method remains the use of a solid spacer or shims, IMHO. The new crush sleeve approach is "adequate" and reusing a crush sleeve may be "adequate" but with reservations noted above.
Just my 2 cents on this issue. joe
Subject: Re: [RAM] gearing installs??
From: Stephen D Belt
> I believe my 95 RAM1500 5.2L 4x4 has 3.50 gears in the diffs. I want to take it down to between
> 3.83-4.10's. Does anyone know how involved it is to do this yourself, or is it too hard?
> I am fairly mechanically inclined, but probably not willing to completely disassemble an axle.
Sorry for my delayed response. Out of town last week, just now catching up.
Anyway, as many know, I've done this one myself, including an ARB up front. The rear end, with Limited Slip, wasn't too bad, but like mentioned in other posts, you do need a lot of special tools. I'll site a few here:
Unless you are very mechanically inclined, and have read the FSM, I wouldn't
attempt the job. One extra I have, is a brother-in-law that is a trained
mechanic, and had done the job before. His experience proved invaluable
in setting up the rear end. I also spoke with 3 pro gear change guys at
local shops (including one Dodge dealership), asking them which tools
they actually use, compared to what is in the FSM. The one tool I thought
I would need but didn't was the case
spreader ($125 from Miller Tools).
PS- I've got some more details on my web
PPS- When completely done, with all costs added in, I was close to $2000 for the entire thing.
1995 2500HD V10 4x4 -- Phx, AZ
Subject: Re: [RAM] gearing installs??
Steve Belt is "on the money" about the difficulty. However, I use only the bearing puller out of the list of special stuff that he uses. You can even get away without a dial indicator. Set backlash to zero with zero preload, then move 0.012 shim to get 0.006 backlash, or add 0.012 to the side away from the ring gear mount surface to get backlash and preload in one step. I do use a set of trial bearings--makes it a whole lot easier. They are made from standard carrier bearings by honing out the ID so they just slip fit on the carrier.
Subject: [RAM] 4.56 gear installation info -- LONG!
From: Stephen D Belt
To begin, let me say this is not a job for the weak at heart. I think Chris S. pointed out this is the one job he will not do. After this weekend, I'd say its a job I'd rather not do often, but at least it is something I now feel comfortable doing. My final pattern and backlash were just perfect and there is no audible noise coming from the differential when driven.
The work was done by myself and my brother-in-law Chris. He is a trained mechanic and had performed gear changes during mechanic's school. He had never done one on a real vehicle, just mockup rearends. His experience with some of the tools was quite useful, however. We started at 8am on Saturday and Sunday, quitting at 8pm each day. It's a lot of work, with heavy, sometimes dangerous tools and equipment. If done again, we could easily get it done in one 12 hour day.
The FSM lists about 20 different special tools required for the job. I found the following list of tools essential:
Compressed air -- I owned 3/4" air impact -- rented $25/day 1/2" air impact -- I owned 20 ton hydraulic press -- purchased for $200 last week bearing separator w/ press off attachment -- rented $13/day 2' pry bar -- I owned 6 1/2 lb rubber end sledge hammer -- purchased at Nappa for $50 1 5/16" socket for pinion nut -- purchased at Sears for $15
Other than the above, you need the obvious compliment of sockets and wrenches, jacks, and lift to raise the vehicle. I don't know how many times I repeated to Chris that without air, this job would be nearly impossible. You have to "wrench" on the differential quite often, and without an impact wrench that would mean the differential would need to be held in place by a soft jawed vice as depicted in the FSM. As well, I can't imagine how you'd get the pinion nut off without air. Again the FSM method (including all of the special tools) would need to be employed.
Disassembly was pretty straightforward. The LSD doesn't have any clips to lock the axles into the carrier, so axle removal is a breeze. The carrier comes right out with a box end wrench attached to a ring gear bolt and then a solid 1/2 turn of the yoke. From there it just needs a little extra prying.
I attempted to remove my pinion nut with my Chicago Pneumatic 1/2 impact gun (rated at around 350 ft-lbs), but had no success. This caused me to go rent the 3/4" drive air impact, which was able to remove the pinion nut, as well as tighten it enough to get the correct pre-load on assembly.
Bearing extraction was done with the bearing separator and an impact wrench on the press bolt. The new carrier bearings were pressed on with the press and one of the old bearings. The pinion bearing was pressed on with the press and a piece of 2" pipe connector made of galvanized steel.
I did a heart transplant of the old "guts" of the LSD into my new carrier. This was again simple and straightforward.
The first installation of the carrier into the rearend wasn't able to be attempted until Sunday morning, as all day Saturday was consumed with chasing down the 3/4" air, replacing a bearing that was shipped to me incorrectly, getting the pinion nut socket, and a slew of other mishaps. This first install took quite a while (~20 minutes), but we learned what worked, where to pound with the sledge, and eventually got it down to about a 5 minute job by the 6th and final time.
This first install had a backlash of zero (need .005-.009") and a pattern that showed a shallow pinion depth.
We made some shim adjustments and got the pinion depth too deep, and the backlash up to .015". So, we knew the correct pattern was somewhere in between. It took three more times to get the correct pattern and backlash.
By this time it was about 5:30pm. Those last three setup attempts took about 45 minutes each. Axle and drive line install was a breeze. 1/2 hour was spent filling the diff with 1.2 gallons of 80w90 with friction modifier.
Finally, road testing began. I put the first mile on here in my driveway on the blocks. We listened for any hint of gear noise. None! We were pretty relieved, and the rest, you already know.
Again, there was a point on Sunday where I had serious doubts about whether we were going to be successful or not. The carrier installation was not trivial, and neither was the bearing removal, without that specialized bearing separator. But now, I know its not an impossible job, and one that with patience and some decent planning can be accomplished by a shmuck like myself.
If this is a project you plan to attempt, look me up, and I'll give you some more tips and jig building info that proved to be invaluable to me. And if you read all the way to here, thanks!
Steve Belt 1995 2500HD V10 4x4 -- Phx, AZ
> Also, to get the pinion bearing off and on the pinion
> couple of tools, unless I want to take it in to a machine shop. However,
> since this will likely have to be done a few times, for shimming, that could
> end up costing too much and/or taking too long.
Here's a trick. When you get the old pinion out, take that bearing off. Using a small grinding wheel on a drill, or a dremmel tool, grind out the inner section of the bearing (make sure you keep it smooth) so that it just fits tight on the OLD pinion. Then use some sandpaper to smooth it more. Use this to set up the new pinion. Can do the same with carrier bearings. It does take time to do this, but the result is a setup bearing that is easy to work with and doesn't stress the parts. (also saves $$ on fancy pullers as you can hammer the old one if you don't care about the pinion.)
Christopher Siano CSiano
Dana 44, Dana 60 Diff setup info at Allan W's IH Truck site
D60 Notes - From Hot Rod January 2001
When rebuilding the axle, check the carrier bearing thrust surface (side of the carrier closest to the ring gear) for wear, overheating, or metal transfer from a spun carrier bearing. This surface takes all of the carrier thrust under load, and damage will make it difficult to set the proper bearing preload. Specialized equipment is needed to repair damage to the thrust face.
Check the housing for cracks, especially at the housing ends that support the axle tubes.
When repalcing the ring and pinion gears, some trial and error is needed to set the pinion depth. If you have the original pinion depth shims, use them for the first attempt. If the original shims are damaged or unavailable, start with a 0.035" shim and go from there.
The pinion bearing preload shim needs to set the bearing drag for 18 to 25 in-lb with a new bearing, and 10 to 15 in-lb with a used bearing. Shimming 0.085" will often put the preload into the "ballpark".
Yoke PN 3-4-5731X accepts a Spicer 1350 U-Joint with u-bolts - much stronger than the 7290 U-Joint with stamped steel straps and bolts. Torque the pinion nut to 250 lb-ft using a tool to prevent the yoke from turning (note: an impact wrench capable of generating 300 lb-ft will do the job without the holding tool). Use thread locking compound to keep the nut tight.
Two carriers are used for the Dana 60. The thick gear carrier accepts 3.54 to 4.10 ratios. The thin gear carrier accepts ratios numerically higher than 4.10. A Mopar Performance ring gear spacer and bolt kit (PN P3549856) permits 4.56 and up (thin gear) ratios on thick gear carriers, but strenght is lower when using this kit.
Apply thread locking compound to the ring gear bolts and use the bolts to draw the gear onto the carrier evenly. When the gear is fully seated, tighten the bolts to 110 lb-ft.
A case spreader is not required to install/remove the carrier, and careless use of a spreader can permanently damage a housing (spreading the case more than 0.020" will permanently distort the housing). Install the carrier bearings and install enough shim to produce a snug fit in the case (usually about 0.050"). Then remove the carrier and add 0.010" of shim to get the correct preload. Use a soft hammer to install the carrier and torque the caps to 105 lb-ft, then measure the backlash.
To get the wear pattern, coat the ring gear with white grease and use a drill to spin the pinion while holding a slight drag on the ring gear. A gear pattern chart will show which way shims must be adjusted to get the correct pattern.