Raspy

I put a dynatrac kit on my truck years ago. One of the first, I think.

After having many 4WD trucks, for many years, I just could not justify the unit bearing setup. I was at 110,000 miles and ready for new ball joints, etc.

After another 80,000 miles I began to have trouble with it. First a grinding noise when in 4WD and then a Warn hub came apart internally and would not engage. I inspected it and re-installed it thinking it was a fluke. Then it happened again, which left me stranded and blocking traffic in a severe snow storm in the Sierras.

OK, order new Dynatrac hubs and get on with it. Well, they were some of the first ones and came with a plastic bushing inside that failed and prevented them, from engaging! Eeek. Stranded in another storm with no 4WD. Man, this is getting old!

So now the good part. I found the main problem! The bearing in the back of the spindle that supports the stub axle, failed. This allowed the axle to flop around and take out the hubs. The bearing was gone and the axle was running in the bearing race. This also caused the locking hub to chew itself up and send ground steel through the hub area. New stub axle, new locking hub, new axle bearing, new seals, major cleaning, and back on the road.

Since I had an early version of the Dynatrac hubs with the plastic bushings, Dynatrac warranteed them and sent me a new one and a bronze bushing for the one that was still OK.

For everyone that has this setup, be sure to check this inner bearing if you get any noise or are in there to repack the wheel bearings. I know it's a hassle to remove the spindle, but it must be done!

I also replaced the ball joints since I was in there anyway. The Moogs that I had been running for 80,000 miles made the truck handle poorly and I never liked them. By the way, the upper Moog is NOT a ball joint, but a simple sleeve bearing on a pin. I went with Dynatrac ball joints. They are true ball joints and seem to be high quality. On my test drive I can tell the truck handles better already.

Conclusions: 1. The free spin kit may not be practical for everyone. Its expensive, saves little if any fuel (I could not see any improvement), and requires more maintenance. At least you can do some maintenance, but it's not easy. 2. Get good ball joints and greaseable U joints when you do go in there. Moogs are junk. My greaseable 464 Precision U joints are still OK, but they must be greased regularly! Water came out of mine during this work and I grease them at least every 10,000 miles! 3. Dynatrac ball joints seem to be high quality units. They say they don't need greasing, but because of demand, they started building them with grease fittings. The top one uses a standard zerk, but the bottom one uses a needle type that points straight up toward the U joint. Good luck greasing that one! They are "rebuildable", but I don't think that matters one bit. The only thing you avoid in a repair is pressing out the old one. Instead you take it apart. No real gain that I can see as everything else still comes out to get to it. 4. Dynatrac is a good company that builds good stuff and stands behind it. 5. I do not want to do this again! Sheesh. I can do all my own work and I insist on doing it. Otherwise, all this would really be expensive. Plus, I'm stubborn enough that I'll work on it outside in a snow storm instead of getting towed.

d6c

Good post... The spindle inner bearing is one of the reasons the manufacturers went away from this system. The bearings don't seem to have the durability to turn all the time (hubs locked) and the same bearing gets hammered on if the shaft is dead (hubs unlocked) I've got two of the dynatrac systems, one is not installed yet. I also saw no mileage improvement.

etn550

Yes good post. If I go with a free spin kit it will be mainly to use 2wd low for backing trailers. I smell clutch too much in reverse with trailers. Why on earth is reverse gear so high? Can't coordinate and move steering lock to lock quick enough with the clutch out in reverse!!!!!

Jim O

That is exactly why I went with the freespin kit I believe the NV5600 reverse gear is even a little higher than the G56. As for milage I read in a magazine (not sure if it was 8 lug or Diesel Power or Diesel World that the free spin kit allows 106 lbs. of parts to stand still instead of turning them so I think there must be some fuel savings. The magazine did a 200 mile test circuit befor and after and if I remember right they found about a .7 mile per gal. savings. I have not enough miles to really see a gain, but like I said I wanted the low reverse in two wheel drive. I have to back around a power pole and cut to the left then a hard right to put the trailer on the pad behind my house, and this is all on dry pavement. It is so nice to be able to do this with out the hump hump of four wheel drive.
To get back to the inner bearing problem what is a good time to do a repack assuming normal driving winter and summer without river crossings, I was thinking about 50,000 miles or 80,000 kilometers what do you guys think.
Jim O

steve05ram360

thanks for the heads up... I just installed a spyntec kit & will have a look at that bearing when I service it.

as for mileage... I kept hearing 1 maybe 1.5 mpg with the swap so wanting to know 1st hand I did an approx 120 mi loop the week before the install & got 18.2 mpg, did the same loop after the install & got a 20.1... kept speeds the same & ran it at about the same time on a sat. night so traffic would be light. differences were the weather was about 10* cooler on the 1st run & had stronger winds on the 2nd run... planning on doing a 2nd run just because I find it hard to believe...

btw... my truck has only passed the 20 mpg mark 1 time... so this was the 2nd.

Raspy

Jim,

As far as re-pack scheduling I think you are pretty close with the 50,000 mile interval. I went 80,000 miles and the wheel bearings were fine to re-use. I solvent washed them and the hubs to as clean as I could get them. Then repacked with a good quality grease. Unfortunately, with the destruction of the locking hub, I went back in and did it all over again, plus the things I mentioned. I also did not do the inner bearing the first time (at 80,000 miles).

It would definately be a good idea to remove, inspect and re-pack the locking hubs way before that mileage. When unlocked they have a lot of sliding on small sleeve bearings going on. Initially they produce a fair anount of heat as the grease gets pumped around.

When I finally did remove the spindles, one inner bearing was completely destroyed and had ruined the axle, while the other one was fine. The U joints had water in the bearing cups. I have not submerged the front axle.

I'm also mildly concerned about the outer wheel bearings as both of the bearing races have been turning on the spindles. I did nothing about this and will look at it again next time. So far it has not lead to severe damage, just a mark.

So, this time I greased the U joints with green boat trailer wheel bearing grease and the wheel bearings got Mobil 1 red synthetic grease.

Don't justify this conversion with potential fuel savings. It will give 2WD low and it is a better overall design, maybe, but it definately is more complicated. Some of the savings in rotating friction over the original design is used up in pumping grease through the locking hubs sliding surfaces which must be adequately lubed and regularly serviced, to survive. If they ever go under water they have to come off and be serviced. When there is a problem with the inner axle support bearings, and/or the hubs, you lose 4WD. This problem can sneak up and you might not know it until you're stuck.

hvyhauler

If you are mainly wanting 2 wheel low why don't you put a Remco Driveline Disconnect in the front driveshaft ? This is a much cheaper, easier, and maybe better solution. I did mine soon after I bought my truck new. I normally leave the disconnect in free (except if I really need 4 low) and have 2 low available anytime. I love how it works manuvering trailers.

John

Jim O

That was the main reason but there are other benefits. Your are still turning a small gear with a big gear and that takes some power As I said in the previous post there is between 106 and 112 lbs of parts that are not turning when I drive down the road, You are still wearing out U joints. You still have to service the front diff. as it is always turning. You still have the hub assemblys that give a lot of trouble, I can repack mine and go again on bearings that are located further apart and available almost anywhere.
I would not even consider Remco. I have a friend that bought a new Ranger Pickup to tow behind his motor home. He went with a Remco disconnect and got an awful vibration. Remco did absolutly nothing to help in out. He went to a driveline shop in Edmonton and got a new driveshaft made and they used only the Remco coupling. They told him the driveshaft was welded of center and he told Remco and they did nothing to help him.
Jim O