Ins & Outs of Transfer Case Rebuilds

[Elwood]

Are those cracks or just surface imperfections? Might be wise to clean up the area (wire wheel or media blast) and check with at least a dye detection kit. If that brake drum is actually cracked, even on just one side, I wouldn't use it.

[MSeriesRebuild]

There is a good possibility the cracks do go all the way through. Hard to see until the drum is sandblasted, then cracks typically shine out. This is a cast piece, because of the type of material, it is extremely hard to perform a successful crack repair. Usual outcome results in the drum cracking completely in pieces when heated for repair. New NOS drums don't exist as far as we can find. We have successfully fabricated, machined, and balanced new drums that fit and perform better than the originals, and they don't crack due to heat stress. We have drums in stock.

[06boblee]

There are definitely small cracks that can be seen, - another part to buy!

[ashyers]

The clay like material you see was gearlube. It was about 1/8" deep and filled the entire idler gear. The amazing thing is the bearings didn't look too bad and had no signs of heat damage. The gear teeth looked OK other than some signs of moisture damage.

IdlerFunkSmall.jpg (34.41 KiB) Viewed 2498 times

On the shaft you can see the wear on the short trapezoidal splines. This is where a fair amount of the backlash I was seeing came from. The fork had some pretty significant damage. Looks like it was preloaded into the clutch at some point and fried.

Fork&InputSmall.jpg (238.09 KiB) Viewed 2498 times

I'm working on picking up a NOS transfer case. I will avoid rebuilds as I'd like new guts. I sure don't need a "parts" box... On the other hand, I may have one soon!

Bob,
Those cracks are kind of scary. I'll have to check our drum, but I think it's fine. That would make a hell of a Frisbee!

Andy

[Elwood]

Being advertised as NOS isn't a guarantee of serviceability inside. If it was stored improperly (NOS would mean it's been sitting around for some 50 years now, perhaps in unheated warehouses), it could still have plenty of corrosion on the gear teeth and bearings.

The TM on rebuilding these things instructs to drain the lube for storage, so even the lower areas wouldn't have had much protective oil on them.

Not long ago, I unwrapped an NOS idler gear for the NP200. It was still in the original box and the oil paper wrapping. Yep, it was unused, but it had pitting on some of the teeth.

[MSeriesRebuild]

Elwood is exactly right with the possible condition of NOS components and individual parts. We've used the phrase that today's NOS stuff is like the old gray mare, "ain't what they used to be." As time goes on, it takes a toll. Storage conditions and care during storage is everything, and not much concern in the eyes of some vendors who see only $$$ signs from buyer's who drool when "NOS" is in the description. It is most definitely "BUYER BEWARE."

Viewing the pictures posted above, in many cases the forks are repairable, we have built up and resurfaced many. Can't see the kind of detail in this picture needed to make a smart determination. The shaft splines don't look that bad in the photo, of course pictures are very deceptive because you can't see nearly enough detail. The splines still have the correct shape in general, a new shaft will look exactly the same. Again can't see enough detail in the picture to make a determination of serviceability.

[ashyers]

The "new" transfer case should be on its way tomorrow. The vendor has pulled the rear driveshaft's output shaft and all looks good inside. We'll swap the flanges and seals and pull the other output shaft so we can check things over. I was looking forward to a "rebuild" not a "replacement", but that didn't make sense with the cost of parts.

I did have a question regarding the mounting bushings. The ones in the truck are in surprisingly good shape as far as cracks/rot. I'm wondering if they have taken a set and are compressed a bit. When the bushings/stand off assemblies are tight how much compression should the bushings have (how tightly should they grab the mounting brackets). My sense is they should have zero float, but I'm not sure if they should be clamped tight either.

Andy

[Elwood]

As long as you're going to pull the brake output retainer assembly, too, consider disassembling the entire transfer. You'll then have an opportunity to inspect and measure everything, to upgrade parts if you want (e.g. stainless shift shafts), and to then re-assemble the unit and know without any doubt that the bearing crushes and tolerances, the gasket compression on the front ball-bearing retainers, etc. are correct.

Just a suggestion, but I've come to not trust "rebuilds" or "new" or "NOS" unless they're from the one or maybe two shops that I trust.

If my memory is working this morning, those rubber isolators should be solidly compressed when installed. There's no torque spec on the through bolts, but that transfer case shouldn't be moving around.

[MSeriesRebuild]

Elwood offers some really GREAT advice concerning full disassembly and checking out any case you purchase unless you KNOW you can fully depend on the vendor's associate who is offering the info. Next question is DOES HE REALLY KNOW? We have been in this business a long time; CAUTION: all vendors are not straight up, yes there are some mentioned occasionally on this forum as being great, well not so much, I speak from experience, I'll leave it at that. Simply a word of caution, you make your own decision. Since you have said you looked forward to doing a rebuild anyway, go ahead and go through with that when you get this case is the best advice anyone can offer to you. If at the very least you don't find some rust pit damage, you will have found the crown jewel of cases. Certainly simply removing the rear drive unit does not reveal all you need to visually check out before putting the case in service.

I broke open a 5-speed some time back that was really dirty and rusty on the exterior, but the interior was rust free and perfect, so it does happen. On the other hand, I've broke open some that were perfect outwardly, but were a rust bucket on the inside. Bottom line, no way to tell without total tear down, cleaning, and inspection. These components are 50+ years old in most cases, you should treat them as such.

Isolators should have a solid crush, this procedure is actually built into the assembly so you can't do it wrong. You should have 4 pieces that look like tubes with a big washer attached to one end, isolators slide over the tube. The length of the tube controls the rubber isolation crush as the bolt is torqued. When the end of the tube contacts the cross member, you begin to feel resistance quickly as you tighten the nut. The length of the tube prevents over or under crushing of the isolators, IF the isolators are in good condition. Torque the bolt to the required spec., you should then be able to visually inspect the rubber for correct crush.

[06boblee]

Elwood offers some really GREAT advice concerning full disassembly and checking out any case you purchase unless you KNOW you can fully depend on the vendor's associate who is offering the info. Next question is DOES HE REALLY KNOW? We have been in this business a long time; CAUTION: all vendors are not straight up, yes there are some mentioned occasionally on this forum as being great, well not so much, I speak from experience, I'll leave it at that. Simply a word of caution, you make your own decision. Since you have said you looked forward to doing a rebuild anyway, go ahead and go through with that when you get this case is the best advice anyone can offer to you. If at the very least you don't find some rust pit damage, you will have found the crown jewel of cases. Certainly simply removing the rear drive unit does not reveal all you need to visually check out before putting the case in service.

I broke open a 5-speed some time back that was really dirty and rusty on the exterior, but the interior was rust free and perfect, so it does happen. On the other hand, I've broke open some that were perfect outwardly, but were a rust bucket on the inside. Bottom line, no way to tell without total tear down, cleaning, and inspection. These components are 50+ years old in most cases, you should treat them as such.

Isolators should have a solid crush, this procedure is actually built into the assembly so you can't do it wrong. You should have 4 pieces that look like tubes with a big washer attached to one end, isolators slide over the tube. The length of the tube controls the rubber isolation crush as the bolt is torqued. When the end of the tube contacts the cross member, you begin to feel resistance quickly as you tighten the nut. The length of the tube prevents over or under crushing of the isolators, IF the isolators are in good condition. Torque the bolt to the required spec., you should then be able to visually inspect the rubber for correct crush.

Charles, do you have any known options for replacement rubber isolators other than oem (50 years old) items?

[Elwood]

Vintage Power Wagons (and maybe Midwest Military?) has new reproduction rubber isolators available according to their current catalog, p. 47: https://drive.google.com/file/d/0BxzO_O ... 4zM3c/view

[MSeriesRebuild]

I have not heard of repro isolators, but I believe the last box full we bought was from VPW. Those were good condition.

[06boblee]

I got a set from Midwest, OEM--old. Don't get me wrong, they are way better than the set I took off. Was just wondering if there were any "new" ones.

[CSCameron]

I think Chris Case over on the Power Wagon forum was making them out of new materials? You might check there.

Here is a link to his photo album showing a set he made out of blue urethane...
http://imageevent.com/bigchriscase/bodymountsurethane



Clark

[ashyers]

Here's some photos of the NOS case I picked up:

The M37 Flanges are on loose for shipping. All of the seals are double lip rubber seals, not leather. The case had M715 style yokes.

NOS Frt.JPG (130.94 KiB) Viewed 2385 times

Now I know how thick the asbestos is supposed to be! Picked up a new flange for the D-shaft too, the current one lost it's press on the bearing cups and they were walking a bit.

NOS Rear.JPG (114.88 KiB) Viewed 2385 times

We'll be tearing down the case to remove the grease that's on the needle bearings. It's become a bit like glue from age. The good news it from what I can see the gears and bearings look nice and new inside. I'm amazed that I could still purchase one of these!

NOSRearOutput.JPG (131.79 KiB) Viewed 2385 times