8k axle and electric over hydraulic upgrade

**pilotpip** · 08-26-2022, 02:46 PM

Originally Posted by huntindog

From what I have read, there is one big advantage in favor of 8K axles. You can convert to oil bath hubs. I will be doing this at service time.
Then the maintainence is a lot less frequent.

But when it is, I bet it's costly. Axle bearings don't bother me. Ideally they'd switch to a sealed bearing system like we see used reliably on our vehicles for 100,000+ miles, but we all know that would cost them a couple dollars.

**Second Chance** · 08-26-2022, 03:01 PM

Originally Posted by pilotpip

But when it is, I bet it's costly. Axle bearings don't bother me. Ideally they'd switch to a sealed bearing system like we see used reliably on our vehicles for 100,000+ miles, but we all know that would cost them a couple dollars.

The maintenance would not be more costly - just messier.

There's a big difference between automotive bearings carrying 7 - 8K lb. vehicles and RV bearings carrying 13 - 23K trailers. There are some bearings called Nev-R-Lube that are sealed bearings for RV and trailer applications. They have a significantly higher failure rate than good quality Timken bearings with proper maintenance. MORryde offered them for a while but had too many people returning to have them replaced with Timkens because of failures.

Rob

**huntindog** · 08-26-2022, 04:28 PM

Originally Posted by pilotpip

But when it is, I bet it's costly. Axle bearings don't bother me. Ideally they'd switch to a sealed bearing system like we see used reliably on our vehicles for 100,000+ miles, but we all know that would cost them a couple dollars.

There is such a thing. My 2010 Sabre had them. I lost a wheel when one failed. The problem with the sealed bearing RV hubs is that the inner and outer bearings ar too close together, with no space between then like standard bearings have. They just cannot take much sideways force setup that way. Lippert discontinued theirs, but I believe Dexter (same units as far as I can tell) is still making theirs.

**huntindog** · 08-26-2022, 04:40 PM

Originally Posted by Second Chance

I had a conversation with a MORryde engineer about this after it was suggesting by a Coast Guard naval engineer in our FamCamp that I could do that with the hubs on our IS. (This naval engineer admitted that he's used to working with machinery that it takes a hoist to lift.) The MORryde engineer's response was that they don't recommend it. He explained that the tractor trailers that use oil bath can count the internal volume of the hubs and axles in liters - similar to the rear axles on our trucks that have a cavity all the way across and a large volume of lubricant; the internal space of the hubs on our rigs is measured in milliliters. The resulting lack of air space for oil to expand into (compressing the air) results in much higher pressures in the smaller hubs, forcing oil out the seals and sometimes compromising the oil caps. If it weren't for that, I would also love to gain the maintenance advantages of oil bath. Can you point me to some reputable sources to do some more reading?

Rob

Dexter only has one caution on oil bath: That the upper rollers can become dry in long term storage, and subject to corrosion.

I am not that concerned about that in Phoenix, plus my coach doesn't sit much.
I think there is enough volume inside the hubs. There have been many reports that it takes almost an entire tube of grease to fill the cavity when using the EZ lubes for the first time.... And those reports are generally for 3500# axles. My 8000# axles are much larger

**huntindog** · 08-26-2022, 04:53 PM

When I was looking over the Dexter site, I noticed that there was no service interval listed for oil bath bearings.

Etrailer states that all that is needed is a look to see if the oil level is correct, and that it does not look milky IOW, unless something is going wrong, they are maintenence free.
I did notice that Etrailer does sell oil bath kits for axles as small as 3500#....But I am pretty sure I have read in the past that Dexter only recommends it on 8K and up.

**LMagelitz** · 08-26-2022, 05:15 PM

Originally Posted by Second Chance

The MORryde engineer's response was that they don't recommend it. He explained that the tractor trailers that use oil bath can count the internal volume of the hubs and axles in liters - similar to the rear axles on our trucks that have a cavity all the way across and a large volume of lubricant; the internal space of the hubs on our rigs is measured in milliliters. The resulting lack of air space for oil to expand into (compressing the air) results in much higher pressures in the smaller hubs, forcing oil out the seals and sometimes compromising the oil caps. If it weren't for that, I would also love to gain the maintenance advantages of oil bath. Can you point me to some reputable sources to do some more reading?

Rob

The MORRyde guy isn’t quite right on that. The drive axles yes….there are gallons of oil in the differential and a shallow amount that goes out to the outside bearings on the drive axles of a semi tractor. All the other wheels on a semi, including the fronts, are a hub and outside metal cap with clear sight window. The oil in those is only about an inch deep (if that), and maybe totals half a quart of 80W-90 gear lube. A set of tandems fully loaded is 36000lb, so 9000 per hub. A 15k lb GVWR 310GK would put 3000lb on each hub, after subtracting maybe 3k of pin weight. The RV hub volume is less, volume of oil will be less, weight carried is approx 1/3. Relationally, I can’t see there being a reason for a significant pressure difference.

We are going in January to MORRyde for IS…I’ll talk to them about oil bath. It would be nice to do it while they are switching everything over.

@pilotpip I’d get the disc brakes and axle upgrade. I had the brake controller set a little hot the first time I put the brakes on, and thought I was going to rip the hitch out of the back of the truck! They are fantastic.

**ajg617** · 08-26-2022, 06:27 PM

Originally Posted by Wileykid

One thing to know, is that in order for the higher GVWR, the 8K lb axle's must be done on the production line, if you do it yourself afterwards with all the same parts, it will still be listed as the lower GVWR, they will not increase it after production even though it would be the same.

Just a quick note - the higher GVWR with the 8Ks is not a given when installed at the factory. I called GD before we ordered and was told that they had no policy which automatically increased the GVWR as management has been back and forth on this one. I was told to insure the dealer put the 18K (in my case) GVWR request clearly on the order sheet next to 8K option they sent to GD. That worked for me.
I don't know if they have changed that policy but that was when we ordered last Nov.

**pilotpip** · 08-26-2022, 07:39 PM

Originally Posted by Second Chance

The maintenance would not be more costly - just messier.

There's a big difference between automotive bearings carrying 7 - 8K lb. vehicles and RV bearings carrying 13 - 23K trailers. There are some bearings called Nev-R-Lube that are sealed bearings for RV and trailer applications. They have a significantly higher failure rate than good quality Timken bearings with proper maintenance. MORryde offered them for a while but had too many people returning to have them replaced with Timkens because of failures.

Rob

Interesting. I guess I should say "quality" sealed bearings. It's amazing how much more stout the timken seals, bearings and races were than what were installed from dexter.

**Wileykid** · 08-26-2022, 08:24 PM

Originally Posted by ajg617

Just a quick note - the higher GVWR with the 8Ks is not a given when installed at the factory. I called GD before we ordered and was told that they had no policy which automatically increased the GVWR as management has been back and forth on this one. I was told to insure the dealer put the 18K (in my case) GVWR request clearly on the order sheet next to 8K option they sent to GD. That worked for me.
I don't know if they have changed that policy but that was when we ordered last Nov.

Interesting, I ordered mine in January of 2021, which was the first time they were offering the 8K axle option on the 320G. I had no idea that it would increase the GVWR, I wanted the axle margin, and disc brakes. I found out when mine was delivered and I looked at the weight sheet for the trailer.

**ajg617** · 08-27-2022, 04:56 PM

Originally Posted by Wileykid

Interesting, I ordered mine in January of 2021, which was the first time they were offering the 8K axle option on the 320G. I had no idea that it would increase the GVWR, I wanted the axle margin, and disc brakes. I found out when mine was delivered and I looked at the weight sheet for the trailer.

@Second Chance mentioned that in an early question on 8K axles. When I called GD, it was not a given upgrade on the placard unless the dealer specifically requested it.