4.89 gear set install?

[aussiecowboy]

Has anyone done it yet? I have ordered two sets from Vintage Power Wagon but I'm a bit unsure if I should tackle them myself or not. Does anyone have a reference for settings, parts needed etc?

[Waspworks]

I have a couple of books on the subject Heath.
They are general to all the Dodge trucks of the era with specific details on diff setups for the PW.
Handy to have laying around.

http://www.faxonautoliterature.com/1...ls-P10011.aspx
http://www.faxonautoliterature.com/1...nt-P16275.aspx
http://www.ertelgiftshop.com/index.p...s9ujg6r0s1n6l7


Greg.

[aussiecowboy]

Thanks Greg, have ordered those books. I think I'll probably end up installing the gears myself and then have a mate who owns a transmission shop check them over. I reckon my bearing will be ok to re-use but will order new pinion seals.

[Desoto61]

I would also consider the M37 military manuals. You can find them on CD which is handy since you can reprint the pages you need if they get damaged or greasy. More importantly they are written for less experienced mechanics so the instructions are simpler.

I did my own too, not impossible, you will need to build or buy a few special tools. I think I showed off a few in my rebuild threads. The devil is in the details, take your time and triple check everything. Haven't road tested mine yet though so we'll see if I know what I'm talking about.

Don't forget about the spider assembly, now is the time to see about having it checked or rebuilt. It is its own procedure, and honestly I had Charles Talbert do the one I reused due to the special tooling involved. The other I replaced with an ARB locker.

You might also contact Charles on getting a set of his seal adapters to replace the stock seals with a modern seal that is more readily available and also simplifies future maintenance. Not cheap but nothing about rebuilding these differentials is.

Good luck, let us know how it goes!

[Charles Talbert]

I'll add this

The spider/side gear and thrust washer set up is very important. Most have significant wear in that area. If yours does, you could easily end up with a set up that is very prone to breaking axle shafts, and other issues too. Loose motion in the core of the diff is a MAJOR cause of axle breakage for what many think is no reason. 4.89 gears are a GREAT conversion; as much as they cost, it's just stupid (for lack of a better term) not to completely rebuild the entire unit when installing this high $$$ gearing. I can truthfully say this also, bearings are like humans. Yes they don't like change, every time a unit such as this is disassembled and put back, the set up changes everything about bearings. I have seen more catastrophic bearing failures occur shortly after re-using old bearings in a new set up than at any other time. Reason is always obvious. It is impossible to look at a bearing cone or cup and say these are fine to use again. Truth about bearings is the real goody is very shallow. It takes very little wear to cause an accelerated failure, you will never detect this just by a look see. Bottom line, it isn't smart to reuse pre-run bearings; a failure can ruin that new gear set in seconds.

Build it right with top quality parts, use top quality oil, maintain it correctly, you should have a build that last you a lifetime.

[aussiecowboy]

Thanks for your replies Desoto and Charles. I had a quick look through your build threads Desoto, wow, I will come back and read them fully as time permits. There is a lot of wisdom in your words gentlemen, I have spent the $$$ to buy the gear sets, it would be silly to stop short and half-*** the rest. The problem I face is that there are only a handful of Power Wagons in Australia so the chances of finding anyone who knows these diffs is slim at best. If I deliver the diff centres, gear sets, seal kits and workshop manuals to a diff specialist I guess they should be able to work it out. Are the bearings reasonably standard sizes that a decent bearing supplier should be able to find? I'd love just to ship them both to you Charles but as I'm in Australia that might be a bit hard. And pricey. The diffs should be in pretty good condition only having 21,000 miles on them with no leaks or noises.

[Charles Talbert]

It's likely there will be thrust washer wear, even with the low mileage. I imagine the issue you will run into with a local gear box mechanic is that they will not have the special tooling needed to do the job correctly. No the bearings are not really an off the shelf item here in the US. The pinion shaft bearing cones that go with the double cup assembly are built only by Timken, and are built in limited quantity runs. This makes everything cost more too, a full set for the whole unit is near $700 currently. High $$$ gearing, high $$$ bearings, you definitely don't want to short cut this build.

[aussiecowboy]

You're really starting to frighten me Charles, I'm starting to wonder if I shouldn't just live with the 5.83s. Is that $700 per diff? Where do you source the bearings?

[Charles Talbert]

You're really starting to frighten me Charles, I'm starting to wonder if I shouldn't just live with the 5.83s. Is that $700 per diff? Where do you source the bearings?

Well, I hate to tell you, but if this frightens you, you don't even want to think about rebuilding a whole truck mechanically. Nothing done right is cheap. Yes it's approx. $700 per diff for all new bearings. Every one in there is specialty bearings except the 2 on the carrier. I guess $700 isn't too bad when you consider that they were around $500 back in the late 80's early 90's. When they are built by 1 company, in limited quantity runs, that is like buying custom built parts, and there is no competition, so they charge whatever they please. We work with several bearing wholesalers to get good quality parts at the lowest cost, but honestly there isn't a lot of difference any more.

[aussiecowboy]

Don't get me wrong, it's not the price that frightens me but the fact that I might not be able to find anyone in Australia who can build these right. This is by no means my first restoration project.

[Desoto61]

Well I'm by no means an axle expert, but I don't think finding someone who can rebuild it will be impossible. Outside the spider section the design isn't so unique that a good differential guy won't know what he's looking at, and with the reference material and specs it shouldn't be something an experience person has never seen or heard of, the general design aspects exist in other center sections and the basic goal is the same.

I think the tricky part will be the spider gear assembly, and that's mostly due to the special wrench you would need to find/build to open the case.

I fully believe you can do it yourself, the big issue for me was if finding/building the special equipment needed is worth it. Since I was only doing one spider assembly and Charles is one state away I said no, but for you that might not be the case.

I wanted to do the differentials myself mainly to learn how, and the "special" tools aren't all that difficult or unique to get, the most important ones will be some good guages for taking the needed measurements and the gear grease for testing the pattern.

But like Charles said, between the ARB in the rear axle and all the steering knuckle parts in the front axle plus the gearing change and disc brake conversion they were easily the most expensive part of the truck to rebuild in my case.

[aussiecowboy]

Some good points Desoto. As I see it I have three realistic choices.

1. Have someone local try and rebuild them.
2. Install twin ARB lockers rather than rebuilding the spider units, then I'd only need carrier and pinion bearings.
3. Ship the spider assemblies to Charles for rebuild and let a local shop handle the rest of the diffs.

The third option is looking good.

[Tweety]

Not sure if the ARB's that Dan has made up are produced in Aus or the US, but if they are made down under, should save you a ton of shipping expenses!

[aussiecowboy]

ARB lockers are made in Australia. Annoyingly though, the model for Power Wagons can only be bought in the US.

[Clint Dixon]

ARB lockers are made in Australia. Annoyingly though, the model for Power Wagons can only be bought in the US.

Maybe you could ask Dan Shockley in the U.S. if he would sell you a couple of sets and have them shipped directly from the factory to you. No sense in shipping them around the world twice just to make the shipping companies rich.