Switch to 8K Axles?

[mhs4771]

IS is expensive, but look at the amount of money spent by others trying to fix suspension issues and the number of trips that have been cancelled or delayed because of issues.
We've had IS done to all three of our fifth wheels and in our 100K of travel have never had a suspension issue. So for us it was well worth the cost.

[bshgto]

From PNW

I experienced a suspension failure on the way across county a mere three months before I was scheduled to have the IS installed. I knew it was a question of when not if. As I said I frequently checked the components as I was leary of a failure anyway. The point I am making is that I thought was on top of the issue and in the blink of an eye the failure of the .05 clip that holds the spring pack together did me in.

I noticed one of mine was missing and replace all of them with SS hose clamps some time ago. So far so good.

[Montana Man]

Originally Posted by mhs4771

IS is expensive, but look at the amount of money spent by others trying to fix suspension issues and the number of trips that have been cancelled or delayed because of issues.
We've had IS done to all three of our fifth wheels and in our 100K of travel have never had a suspension issue. So for us it was well worth the cost.

I don't know what IS costs to install. Assuming $6k x three for 100k miles seems
like a lot. I've got that in miles and have spent approx. $1k for suspension maintenance.

I totally agree in spending for whatever one wants. Not debating that. I'm just not seeing a justifiable return for this one.

[kowbra]

Originally Posted by Montana Man

I don't know what IS costs to install. Assuming $6k x three for 100k miles seems
like a lot. I've got that in miles and have spent approx. $1k for suspension maintenance.

I totally agree in spending for whatever one wants. Not debating that. I'm just not seeing a justifiable return for this one.

I'd have to agree on this one... I'm about 50,000 miles in last 10 years, and more recently about 10,000+ per year. I've not had any major issues with just the cheap factory suspension...
Now, it's not perfect, and rutted up secondary roads do move the unit around a lot, so I might be interested in improving ride quality and get better durability as part of that.
The biggest, no matter what for me, is our new unit must have disc brakes. Now that I do see as a problem worth the cost to fix.
The 2021 Montana Legacy package does include disc brakes, but they have also included heavier 7k axles, along with 8k springs, according to the rep... I've not seen one so cannot comment on whether it is significantly upgraded or not. GVWR does not change.

I'm really leaning toward the Legacy package at this point, and try that out for a year or 2 to see how it works out.

Brad

[beeje]

We just had the is installed in June. If you go in solely to get the 7K is installed it will be 3900 for a tandem axle trailer

[Dave10]

Changeing to 8k axles provide larger bearing surface and brakes shoes both of which provide a significant benefit. I would think 8K brake shoes are the most important for safety reasons. the 12x2 shoes on 7k axles are marginal at best for most 5th wheel trailers. In fact I consider them unsafe. The bearing surface increase also provides more reliability. The outer bearing is too small IMHO for 7K axles while it is the same as 6K axles. However. they still need routine maintenance. Disk brakes are the best alternative, but the cost is high while 8K upgrade for standard brakes provides reasonable stopping power.
BTY I still have 7K axles and carry a spare set of bearings in the event of a break down. This has saved me over the years.

[steiny93]

When I read this thread I come away with the following 3 points

1) 8k axles are better then 7k axles
2) Non IS axle setups have problems which are not typically axle specific (having an 8k axle wouldn't necessarily mitigate the common issues over a 7k axle).
3) IS is a good but costly option

[beeje]

Originally Posted by Dave10

Changeing to 8k axles provide larger bearing surface and brakes shoes both of which provide a significant benefit. I would think 8K brake shoes are the most important for safety reasons. the 12x2 shoes on 7k axles are marginal at best for most 5th wheel trailers. In fact I consider them unsafe. The bearing surface increase also provides more reliability. The outer bearing is too small IMHO for 7K axles while it is the same as 6K axles. However. they still need routine maintenance. Disk brakes are the best alternative, but the cost is high while 8K upgrade for standard brakes provides reasonable stopping power.
BTY I still have 7K axles and carry a spare set of bearings in the event of a break down. This has saved me over the years.

While I can't disagree with anything you stated above I can however say the bearing failures are not that common. The bigger issues are in the horse and buggy suspension meaning Broken Springs broken spring bolts broken shackles Etc.
I also think it's rare for the axle itself to have issues other than being out of alignment which is easily corrected at a heavy equipment shop.
As far as brakes go I'm sure the 8K brakes are better than 7 however disc brakes (what's on my unit) are a world of difference compared to drum brakes.
Never tried it but I'm reasonably certain I could stop in less than half the distance of anyone that has drum brakes

[PNW Fireguy]

Originally Posted by bshgto

From PNW

I experienced a suspension failure on the way across county a mere three months before I was scheduled to have the IS installed. I knew it was a question of when not if. As I said I frequently checked the components as I was leary of a failure anyway. The point I am making is that I thought was on top of the issue and in the blink of an eye the failure of the .05 clip that holds the spring pack together did me in.

I noticed one of mine was missing and replace all of them with SS hose clamps some time ago. So far so good.

I considered doing the same before the failure but was unsure abouit the lack of flexibility of the pipe clamp vs the inherent give in the fold over clamp. Nonetheless I had already made the decision to change the suspension months ahead of the actual failure. Others have been less fortunate and had the brackets where the springs connect to the frame fail. I consider that I got off pretty unscathed.

[laverdur]

Unsprung weight is the key here. Just like with your TV or family car, the higher the unsprung weight, the worse the ride. Axles are part of the unsprung weight.

[beeje]

Originally Posted by laverdur

Unsprung weight is the key here. Just like with your TV or family car, the higher the unsprung weight, the worse the ride. Axles are part of the unsprung weight.

I have to disagree with that statement. Before installing the independent suspension lots of things in the camper got jostled around. I found the microwave door open/ things in the cabinets fell over/ refrigerator doors open etc.

Now after the suspension install I can place a plastic cup on the kitchen counter and drive 500 miles and it will still be there when I get there.

I have a previous CAT Scale weighing before the is of 12, 360 on the axles. After the is install I weighed it again at 13750 on the axles. I did have some more weight on that trip but I figure the difference added around 1100 pounds or so.

The fifth wheel now tows perfectly level and smoothly down the road almost like it's not there

[McRod]

Originally Posted by JimOMartin

Hi -
Has anyone thought about making the switch to 8K axles from the current 7K ones? Would provide more buffer on the overall weights. Thanks.

I have swapped out my 7k axles for 8k axles, springs and disc brakes and oil bath hubs. You can order the complete 8k assembly from lippert. Comes on a pallet ready to lift up and bolt on. No breakdown issues since the upgrade. Total cost including installation was $3500 for two axles. The 8k brakes come with minimum 9/16" lugs (5/8" optional), so you have to verify your wheels will bolt back on (most 7k hubs have 1/2" lugs)

[McRod]

As you can see by this weight ticket, I was over weight on the 7k trailer axles by 920lbs. Things break when your over weight...
Even on independent suspensions.

You can draw some mathematical conclusions that my trailer weight is just under 18k. Thats 2k over the gvwr.

[beeje]

Good Lord McRod what do you have in that thing. Nearly 15K on the axles. There's no rig in your signature what do you have. Was that with a full fresh water tank.

Both of my numbers include full freshwater an empty waste tanks

[McRod]

I own the MacDaddy of all Montana's...A Big Sky.

[Texan]

Originally Posted by Dave10

Changeing to 8k axles provide larger bearing surface and brakes shoes both of which provide a significant benefit. I would think 8K brake shoes are the most important for safety reasons. the 12x2 shoes on 7k axles are marginal at best for most 5th wheel trailers. In fact I consider them unsafe. The bearing surface increase also provides more reliability. The outer bearing is too small IMHO for 7K axles while it is the same as 6K axles. However. they still need routine maintenance. Disk brakes are the best alternative, but the cost is high while 8K upgrade for standard brakes provides reasonable stopping power.
BTY I still have 7K axles and carry a spare set of bearings in the event of a break down. This has saved me over the years.

If you have the I.S. and disc brakes installed at Mor-Ryde whether you use 7k or 8k axles they install the 8k hubs and bearings with the 9/16'' studs. I changed out the bearings from the China bearings to the Timken bearings myself but i have heard that Mor-Ryde will change the bearings to Timken as an option.

[beeje]

Mc Rod that doesn't help much. They've been making big skies for at least 10 years. What's the year and model number.

And to the poster yes we had Mor ryde installed new Timken bearings for us while we were there along with a new morryde PIN box spring and the little white pucks

[allenclme]

Originally Posted by Texan

I stayed with the 7k axles per Mor-Rydes suggestion after they weighed my rv. I had decided before i left for Mor-Ryde i would let them decide what was best for my rv as they are the professionals. Just because you have heavier axles does not mean you should carry more weight. Mobile Suites have the 8k axles but they also have 15'' frames where as we have 12'' frames on the Montana's. With the 8k axles you also have about 300 more pounds of weight and this subtracts from your carrying capacity. If your gross weight was 16,000# before the I.S. or what other mod you plan on doing then it is still 16,000# after. As for as ride, the 8k is suppose to ride a little stiffer than the 7k but as to how much different i really don't know. The I.S. i fell is the ultimate suspension improvement. If someone can afford the I.S. then i believe they would be well pleased.

I'm talking with MorRyde now to do an IS and Disc Brake upgrade. They have suggested sticking with the 7k axles as the 8k will stiffen the suspension as the weight of my 5er doesn't need it. They also mentioned that the brake size is the same between the 7k and 8k so no benefit in my mind to going with the heavier axles.

[kowbra]

Originally Posted by allenclme

I'm talking with MorRyde now to do an IS and Disc Brake upgrade. They have suggested sticking with the 7k axles as the 8k will stiffen the suspension as the weight of my 5er doesn't need it. They also mentioned that the brake size is the same between the 7k and 8k so no benefit in my mind to going with the heavier axles.

Interesting... if I have it correct, you have a ~16,800lb GVWR on your Montana? That would be much like the 3791RD floorplan we are looking to order. So, interesting that they do not recommend upgrading to the 8K axles from 7K...

I suspect that the disc brakes on the new Montana Legacy package / 7K axles will not be as robust as the ones MORryde is doing on their I.S. packages, but curious if you know that for sure?

Last, if you don't mind, what's the pricing for the 7K/disc/I.S. package, installed?

Thanks!
Brad

[allenclme]

$7500. They offer a seasonal discount if done in Dec-Feb but I don't know what that is. What was explained on another thread that 2800# of my GVW is on the pin, so with the two 7000# axles (14000#) that's how the total GWV was determined. Mine is about 168xx but it's at CW getting work done so I can't look to get the exact number. MorRyde didn't say I couldn't do the 8000# axles, just that it was not necessary and would make the suspension stiffer.