Switch to 8K Axles?

[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.

[PNW Fireguy]

Switched to 8k IS for improved ride and to remove what I consider to be the Achilles heal the OEM suspension. Take note that none of these items changes the vehicle weight limit indicates on the sticker.

[DQDick]

We also went with 8K when we switched to IS.

[mazboy]

the updated 7K axles have been updated for 2021.


I did try and update my springs with 8K springs but I still had problems, but never with the axle it's self. Love my IS system


I'd look at going to IS rather than updating the axles.

[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.

[Montana Man]

How can adding an 8k suspension improve ride? Would that not be like adding a 3500 suspension onto a 2500 truck? If you added a 10k suspension to a trailer does that make it even better than an 8k? Strength and smoothness are generally inverse given the same design.

[JimOMartin]

Hi -
I agree with what you guys are saying. My question is geared towards regular axles not IS. With the increase in axle load you should gain additional cargo capacity. True the tag won’t reflect it and there would be a limitation to how much the frame would handle but I would think that a switch from 7k to 8k axles (and springs) would safely gain you at least 1000lbs of extra cargo vs. the 2000lb increase in actual capacity gained. I’ve been looking at the 3791RD and the rated cargo capacity is2481 but I’ve seen tags stating 1700 of capacity, which isn’t much hence my question around the upgrade.

[prndl]

It is more than just the rating of the axles. The entire frame, spring, axle and load positioning is engineered into your trailer. If you need to carry more than you are rated for you should buy something that is engineered to carry that weight. It is foolish to just add axle capacity to a structure that is not designed to carry it.

[JimOMartin]

Good points. So what happens when other manufacturers offer axle upgrades? The fundamental structure of the trailer doesn’t change, right? Not arguing, just wondering.

[beeje]

Originally Posted by JimOMartin

Good points. So what happens when other manufacturers offer axle upgrades? The fundamental structure of the trailer doesn’t change, right? Not arguing, just wondering.

IMHO you should put your hard earned $$ towards the IS and be done with the horse and buggy suspension. The difference is night and day.

[richfaa]

We also went with the 8K IS from Mor Ryde.

[kowbra]

Originally Posted by JimOMartin

Hi -
I agree with what you guys are saying. My question is geared towards regular axles not IS. With the increase in axle load you should gain additional cargo capacity. True the tag won’t reflect it and there would be a limitation to how much the frame would handle but I would think that a switch from 7k to 8k axles (and springs) would safely gain you at least 1000lbs of extra cargo vs. the 2000lb increase in actual capacity gained. I’ve been looking at the 3791RD and the rated cargo capacity is2481 but I’ve seen tags stating 1700 of capacity, which isn’t much hence my question around the upgrade.

As you know, Montana does not offer a factory installed 8k axle option.
However, we also considered the Solitude in an RD floor plan, and they do offer a factory 8k axle with disc brakes and 17.5" H rated tire upgrade. AND, when you order that, the GVWR goes up from 16,800 to 18,000. Even with the extra weight of the suspension, the payload gain is right around the extra 1000 lbs of payload as you've suggested.

We ruled out the Solitude due to differences on the floorplan, decor, bathroom storage, closet storage, etc, but I think it was interesting that upgraded suspension and tires was enough to increase GVWR on the Solitude -in other words, they are using the same 12" lippert frame (not changed with the updated suspension and like the Montana's), yet they chose to upgrade GVWR without upgrading the frame...

So, as noted, only the manufacturer can change the sticker with the increased GVWR... but I think you are on the right track that in practical terms about 1000lbs of increased payload with the existing frame is a reasonable assumption. Whether that is a risk one is willing to take is TBD by each person, of course...

HtH!
Brad

[Slow Hand]

I just wish that they would improve the mounting of the shocks. The way mine are mounted it's a wonder they even work. And I bet they don't.

[PNW Fireguy]

Take this for what it’s worth, from my perspective the path you want to pursue still does not address the inherent weakness of the brackets, springs and other hardware associated with the OEM suspension. Yes the axles are rated higher however the rest of the hardware connecting the axles is the same. The saddle brackets still have a propensity to fail due their length and the load on them. Once they fail you are stuck. The leaf springs still rely upon a .05 cents tin clamp to hold them together. Those clips come off all of the time. I got to where I checked mine everyone we pulled out from a location and still had them disappear allowing the leaf spring to come apart on the interstate. For us the axle upgrade alone did not address the iproblem.

[beeje]

That is exactly what I said earlier. Get rid of the horse and buggy suspension and go to Elkhart have Mor ryde put the IS on and your suspension problems will be over

[kowbra]

Originally Posted by PNW Fireguy

Take this for what it’s worth, from my perspective the path you want to pursue still does not address the inherent weakness of the brackets, springs and other hardware associated with the OEM suspension. Yes the axles are rated higher however the rest of the hardware connecting the axles is the same. The saddle brackets still have a propensity to fail due their length and the load on them. Once they fail you are stuck. The leaf springs still rely upon a .05 cents tin clamp to hold them together. Those clips come off all of the time. I got to where I checked mine everyone we pulled out from a location and still had them disappear allowing the leaf spring to come apart on the interstate. For us the axle upgrade alone did not address the iproblem.

I'm not sure about the part that "the rest of the hardware connecting the axles is the same"... however the entire suspension is 8k rated, not 7k rated. That includes more than just the axle, and it certainly includes the spring pack. What do you mean by "the rest of the hardware", and where are you getting this info from?

Thanks, I really am interested in finding out how well an upgrade to 8k leaf suspension practically works.

BTW, IS sounds nice, but I just can't see going all the way to Indiana to get it, along with the price... and, as to leafs being "horse and buggy suspension", while that's partially true, leaf suspension works reliably for tens of thousands of trucks driving millions of miles up and down the roads every year; and newer models having quite plush rides as well!

Brad

[Texan]

I don't think the axles have ever been that much of a problem. How often do you hear someone breaking an axle. Sure it happens but It seems the springs,u-bolts, and brackets are more of the problem than anything. If Mor-Ryde and Lippert would build everything heavier and reinforce the stress points then Mor-Ryde probably wouldn't have near the I.S. business that they have. I can agree that commercially there are still a lot of axle and spring trailers out there with some running 100,000 miles or more in a year but they build there suspension to handle the weight they carry. I doubt these rv's are strong enough to carry there own weight much less the added capacity we all add ourselves.

[beeje]

Originally Posted by kowbra

I'm not sure about the part that "the rest of the hardware connecting the axles is the same"... however the entire suspension is 8k rated, not 7k rated. That includes more than just the axle, and it certainly includes the spring pack. What do you mean by "the rest of the hardware", and where are you getting this info from?

Thanks, I really am interested in finding out how well an upgrade to 8k leaf suspension practically works.

BTW, IS sounds nice, but I just can't see going all the way to Indiana to get it, along with the price... and, as to leafs being "horse and buggy suspension", while that's partially true, leaf suspension works reliably for tens of thousands of trucks driving millions of miles up and down the roads every year; and newer models having quite plush rides as well!

Brad

Go out to your camper and look at the puny leaf springs holding 10 to 13000 lb. Then go look at the rear end of your truck whether it's 3/4 ton 1-ton whatever and look at those Springs that are bearing six seven thousand Pounds. You can clearly see the difference.

Yes it's probably a long Trek to Elkhart Indiana to have it done and yes it is expensive. But for my peace of mind not having to worry about the suspension again is well worth the travel and the cost.

[PNW Fireguy]

Originally Posted by kowbra

I'm not sure about the part that "the rest of the hardware connecting the axles is the same"... however the entire suspension is 8k rated, not 7k rated. That includes more than just the axle, and it certainly includes the spring pack. What do you mean by "the rest of the hardware", and where are you getting this info from?

Thanks, I really am interested in finding out how well an upgrade to 8k leaf suspension practically works.

BTW, IS sounds nice, but I just can't see going all the way to Indiana to get it, along with the price... and, as to leafs being "horse and buggy suspension", while that's partially true, leaf suspension works reliably for tens of thousands of trucks driving millions of miles up and down the roads every year; and newer models having quite plush rides as well!

Brad

My words are from my own experiences. The saddle that the springs attach to are still a common point of failure at the weld. The hardware still have the same MTBF's. I spent a lot of time speaking directly to the factory about this issue at the last rally. The axles frequently are bent, you can look at the sheer number of posts on this site regarding that topic alone. I looked hard at changing my axles and after doing my research including Morryde, I determined that changing the axles would not address my concerns. As Murphy would have it 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. Unlike others who have posted on the forum I did not lose the saddle that attach the springs to the frame.
There are two locations in the US authorized to install the Morryde IS...the main location in Elkhart, IN and another vendor location in Oregon. It is what it is.

[kowbra]

Thanks guys, really good info!

Brad