Front Axle Capacity

BigRig · 09-28-2009, 08:09 PM

Hi,

I am new member to the forum. Can the front axle weight capacity be upgraded or be increased by replacing the axle. Noticed that alot class 8 trucks have a 12,000 pound rating. Thank you.

Bob86ZZ4 · 09-28-2009, 08:27 PM

Good question. I'll be interested to see the answers too. My rig has a 12k front axle. I scaled mine and got 11k on the front wheels. That was with almost full fuel tanks and my fat but sitting at the helm. I thought maybe only having 1k to spare might be bad. But, there really isn't any need because there isn't any way to add more weight up there. There's only one passenger seat up there and my wife is very slender. And I wouldn't think I'd put much in the front storage bins underneath because the rear bins are much bigger. I've seen some huge rigs with monster front tires on them. I think they use some sort of cement mixer front axle or something. I wonder it that would bolt onto where a 12k axle comes off? I bet it would cost a ton.

Radman · 09-28-2009, 09:33 PM

BigRig,

I had mine scaled with totally full fuel and propane. I had no water in the rear-fresh-tank and no load in the garage, both of which would reduce the front-end-load. I scaled at 12,200lbs on the front axle.

I asked the guy that did my alignment and ride height adjustments (a local specialty truck frame shop) and he said that was insignificant. And he agreed that it would not be that way when I added 100gal of fresh water and bike or 2 in the garage hanging out over the rear axles.

He said to make sure your tires are up to the load, then your wheels, then your springs. But within a 5% margin - it really isn’t much to worry about in an RV application.

That’s the conversation that I had for what its worth?

Rad

geofkaye · 09-28-2009, 11:35 PM

....I'M WITH YOU GUYS ON THIS ONE....I CAN NOT SEE WHERE EVEN 50% MIGHT MAKE A DIFFERENCE ON THE FRONT END-ONE SEES THAT JUST GOING AROUND A CORNER AT SPEED FROM THE LOADING AND UNLOADING OF A TURN AND THE WEIGHT SHIFTING FROM ONE SIDE TO THE OTHER.....WITH OUT SET UPS I'D THINK IT WOULD NOT BE AN ISSUE....IF ANYTHING IT MIGHT HAVE SOME SAG IN THE FRONT END-BUT TIME DOES THAT ANYWAY.....geofkaye

Radman · 09-29-2009, 07:01 AM

Well I dont know about your guys, but with time, it seems to me, everything starts to sag...up front, out back - it doesent matter what, who or where.

Rad

BUonM22? · 09-29-2009, 06:16 PM

Question on Front Axle, is springs or Air the better way to go? And, should I look for a greater capacity axle as part of my search for the perfect, well OK, satisfactory rig?

geofkaye · 09-29-2009, 09:19 PM

....AIR IS THE LATEST THING FOR SOME MANUFACTURES TO DO TO MAKE THE RIDE AND HANDLING BETTER....THE DOWN SIDE IS THAT IT IS JUST ANOTHER PART TO FAIL IN THE SYSTEM... I suggest you stay with a springer front end unless the ride issue is paramount to your comfort....having driven an air axle tractor and owning a springer i REALLY CAN NOT TELL THE DIFFERENCE... my truck seems to feel the bumps just like the air bags do....maybe if I was more than 23,000# tractor- with a 12,000# trailer[COMBINED TOTAL WEIGHT-35,000# with all the stuff I {could} carry if I wanted to].....but as it is....well ,unless I carry a bunch of fat girlz to a show....[which isn't going to happen] I can not see a big advantage to airbags...others might not agree-but as an extra it is something I can do without....geof kaye and the Rivercity Group[of skinny girls[-['cept me that is!]

BigRig · 10-03-2009, 05:39 PM

I appreciate everyone's quick responses. Thanks

TomC · 12-07-2009, 09:44 AM

It's not just changing out a 12,000lb axle for a larger one-that's the easy part. The complicated part is will the frame take the extra stress-especially with some of the conversions with long wheelbases. Check with your truck manufacturer before you just change the front axle. TomC

alpharv · 12-19-2012, 07:52 PM

Why would you wont to increase front axel lbs? DOT will not allow you to increase weight on front axle. DUE TO THE SPECS OF THE TRUCK BUILDER AND THE REGS. OF HWY USEAGE. I am a retired truck driver and I know if you change the axle and run over a hwy. scale plate the DOT officer in the scale house will come out and stop you and make you return to the scale house to be inspected and weighed. Then your problems are really going to start.

Bob86ZZ4 · 12-20-2012, 10:47 PM

Alpharv, I would suspect that would only be an issue if you are in fact in any way commercial. If you're truly recreational the DOT inspectors and weigh stations have nothing to do with you. So putting a heavier axle on would be for the owner's personal desire. I wonder if you had an rv that was seriously overloaded and you got into an accident and the lawyers got involved might it cause more problems for an owner? Would it decrease your legal exposure if you had upfitted a higher capacity axle and not overloaded it? I don't know. I'm no lawyer. Just curious.

#90-GTSC · 12-20-2012, 11:34 PM

Have you weighed the truck? Do you think you'll have a front axle weight problem? Whenever I see at T/C motorhome with little or no rear overhang and the generator, water tanks, waste tanks, etc. are ahead of the rear axle(s), I wonder how much weight of the truck is on the front axle and if it isn't too much.

Any pilot (private on up) has to know how to make "weight and balance" calculations for an airplane to determine the center of gravity (CG) of any airplane. While I've never done it for a real truck or talked to the engineers, I presume the calculations are the same.

Simple rule of thumb ... the more stuff you put in front of the rear axle(s) and the closer the heavy stuff is to the front axle ... the more front heavy the truck will be. (But you probably had the figured out already.)

Unless you're deeply committed already to where stuff is going to be on your truck, I'd recommend trying to solve the front axle weight problem by placement of the heavy stuff rather than installing a heavier front axle.

alpharv · 12-24-2012, 08:14 PM

I think if your able to shift some of your heavyest items towards the rear of your rige it might help you to litting he front end. when I end up with my front end over weight I slide my 5th wheel back.

alpharv · 12-24-2012, 08:23 PM

Nice looking rig Bob I am suprized that your haveing front end issuse. I would of thougt the builder would of allowed more room for weight. are you maxed out?

Bob86ZZ4 · 12-25-2012, 09:47 AM

Quote:

Originally Posted by alpharv

Nice looking rig Bob I am suprized that your haveing front end issuse. I would of thougt the builder would of allowed more room for weight. are you maxed out?

I'm not having any front end issues. Is there some other Bob around here?

SHORTS · 12-31-2012, 02:14 PM

The high end stretch coach converters use 16k front suspensions, research shows that the larger than 12k front axles all use the same main beam part number, 16,18,20k, the spindles and bearings are probably all the same for these axles also. the brakes,hubs, wheel offset and tires are capacity related and of course the spring packs will be different.
I'm thinking that an upgraded 18 or 20k axle mounted to airide would give the necessary capacity and adjustability for increased weight without compromising the ride and ride height
Question is, is their a way to legitimatly change the build spec sheet to reflect the change, upfitters regularlt change the titles to reflect their finished products, ie; tanker,box van,reefer,motorhome semi etc.

Patrick · 05-01-2013, 07:22 PM

When Showhauler built mine they warned of too much front axle weight since I wanted the generator up front. They said if I keep the 200 gallon tank of fresh water full under the bed it shouldn't be an issue. It hasn't been an issue but I found the addition of 2000# behind the axle sure make for a smoooth ride!

volvoman · 05-07-2013, 06:33 PM

whats your overall length? whats your length from center of rear axle to rear of car ramp? can you see ends of car out side mirrors? who built car platform?

Patrick · 05-07-2013, 08:21 PM

Quote:

Originally Posted by volvoman

whats your overall length? whats your length from center of rear axle to rear of car ramp? can you see ends of car out side mirrors? who built car platform?

I have a 28' conversion, the truck is rougly 10' and the car platform is 5' roughly. I've never measured from the rear axle back. I designed and built the platform. It was laser cut out of mostly 1/2" thick plate and box welded. It could probably hold 5000# safely. I didn't want to stress when on rough roads so I over bult it. The car is about 4" longer than the RV is wide so you see just about 2" in the mirrors. The 1800# car takes some of the weight off of the front axle making the ride much less harsh. I installed a air bag dump which makes loading/unloading easier.

volvoman · 05-12-2013, 08:36 PM

how did you fasten platform to truck? ramps must be 5 foot? that car a two seater? any back seat or storate area? much room in drivers area of car? i like the idea of car sticking out so you can see it. so your over all lenght is about 43'?
with graphics on car do you think they will think its for business not plesure? which then you would have to follow dot rules.
not trying to start trouble. i was thinking about putting graphics on motorhome but think it maybe a problem.

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