Brakes on tandem axles.

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bscott
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Brakes on tandem axles.

Post by bscott » Tue Aug 19, 2008 1:52 pm

Any disadvantage to brakes on both axles? I am adding a second axle and the trailer guy sez I need brakes on both :?: .

Bob

Frank C

Re: Brakes on tandem axles.

Post by Frank C » Tue Aug 19, 2008 2:34 pm

Disagree!
You don't really need brakes on both axles, but it won't hurt to have them.
Disadvantages are: it's doubling both installation costs and future maintenance.
When running brakes on only one axle, they must be installed on the rear axle.

(FWIW though, I feel you don't really need the 2nd axle, either~! :) )
OTOH . . . Chip has a different opinion in the topic 2nd Axle Drawing.
Chip Hindes wrote:If you skip the second set of brakes, make sure the brakes are on the rear axle. Otherwise, due to the geometry of the tandem axle system, braking can cause wheel hop on the trailer. A good explanation of why this happens used to be on the Champion website; if you can't find it I can explain.

IMO once you've decided on the second axle, the additional cost to add the second set of brakes is well justified.

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bscott
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Re: Brakes on tandem axles.

Post by bscott » Tue Aug 19, 2008 5:39 pm

I was told it's a state law in Colorado---anyway, I had to move my single back to get more tongue weight so rather than spend bucks for that mod I'm committed to the dual axle as I intend to travel mucho miles next year and my wife said she will not ride with me unless we put some redundency under the boat. I have a quote of $1,420 plus 2 Carlisle/rims for $110.00 ea.

Those 14" ers are scary to look at and get really hot in 95 deg. ambient air. :x

Bob

Frank C

Re: Brakes on tandem axles.

Post by Frank C » Thu Aug 21, 2008 3:56 pm

I agree that the factory-installed 14s are inadequate, so I just upsized the wheels and tires to 15 inches. They run a bunch cooler than the 14s, and obviously have extra capacity as a safety margin. I also upgraded from Roger's drum brakes to silver-cad coated discs. That $1200 upgrade for wheels/tires and brakes was less than your's ($1650 for second axle plus tires), and it solves the major issue of drum maintenance.

Unsure why you needed to move the axle back to get adequate tongue wt. Roger sets the axle position to account for a reasonably sized outboard, plus the boat & some gear. Maybe you need to rethink the way you're loading the gear? I never carry fuel in the lockers during travel, and load all gear toward the bow ... no problems here with tongue wt. Mine was checked at a Mayflower yard ... about 8 percent.

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Chip Hindes
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Re: Brakes on tandem axles.

Post by Chip Hindes » Thu Aug 21, 2008 6:02 pm

Frank wrote: Roger sets the axle position to account for a reasonably sized outboard, plus the boat & some gear.
Not sure where that comes from. It's been obvious for years that Roger sets the axle position based on no or at most a modest outboard, in order to keep both the tongue weight and tow weight down, so he can then claim the boat can be towed by a (insert "Taurus" or other inadequate tow vehicle model here).
Frank wrote: I never carry fuel in the lockers during travel, and load all gear toward the bow ... no problems here with tongue wt. Mine was checked at a Mayflower yard ... about 8 percent.
Somwhat contradictory. If you can only tow with empty fuel tanks or you have to move all the movable gear forward, then by definition you have a problem with tongue weight. You can't always guarantee the tanks will be empty when you load up the boat; and at some point, you'll either fill them on the trailer or be prepared to pay 30% more for gas at the marina fuel dock. Then the fuel tanks are either in the lockers where they belong, or, or as I had to do once before I solved the tongue weight problem, moved up to the v-berth. Didn't want to do it, had no choice. By the same token, it is nice to be able to load the boat in the fashion in which it will be sailed, rather than have to move stuff forward to tow, then back where it belongs for sailing/motoring or storage. Not having to move stuff around is also on reason I got to the point I could be sailing within 20 minutes of arrival, on the road within 30 minutes of docking.

Finally, after lo these many years, there's still not one person other than Frank who thinks 8% is adequate tongue weight. It's 10% minimum, always has been, always will be.

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MacHarris
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Re: Brakes on tandem axles.

Post by MacHarris » Fri Aug 22, 2008 7:06 am

is it a legal requirement to have brakes on the added axle?

i was told it is necessary, but that's here in Canuckistan... :D

..

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Andy26M
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Re: Brakes on tandem axles.

Post by Andy26M » Fri Aug 22, 2008 8:11 am

In some states the law requires brakes on both axles, in some states only the rear axle. So, it depends on where you plan to tow the boat, I guess.

- Andy

Frank C

Tongue Weight & Tail-wagging

Post by Frank C » Sat Aug 23, 2008 4:09 pm

Chip Hindes wrote: . . . Finally, after lo these many years, there's still not one person other than Frank (?~!)
who thinks 8% is adequate tongue weight. It's 10% minimum, always has been, always will be.
Unfortunately (after lo these many years) Chip remains content to rely on anecdotal rules of thumb for travel trailers, rather than doing some research on the larger industry, especially the boat trailering industry.

In fact, there's a very simple and obvious reason that guideline tongue weights of boat trailers are less than that for travel trailers. The typical billboard profile of a travel trailer, at speed, tends to lighten its tongue weight due to air resistance. A boat's bow, by contrast, is notably streamlined into that same airstream. For this simple, obvious & straightforward reason, boat trailers are usually specified for lower tongue weights than most other tow-loads. It's also the justification for some vehicle manufacturers specifying a higher wt limit for towing a boat than a conventional trailer.

Further, while Chip advises A MINIMUM of 10% tongue weight, in fact ten percent is the MAXIMUM tongue weight authorized by hitch manufacturers. The Class III hitch that most of us are using (5000# rating) has a maximum 500# tongue wt. limit (see Reese link at bottom).

True enough, after loading your Class III hitch at 4500# (average gross weight of a trailered Mac 26) you COULD potentially carry a tongue wt up to 500# (thus accomplishing an 11 percent ratio). However, that is unnecessarily overloading the tow vehicle, as far as most boat trailering guidelines I've ever seen ... to wit:

DIY Network re Autos & Boats
Important Terms: When specifying the towing capacity for a particular class of hitch, guidelines will typically refer to two separate measurements ...
  • The gross trailer-weight is the weight of the trailer fully loaded -- i.e., the combined weight of the trailer and the contents it will be carrying.
  • The tongue weight refers to the downward pressure applied directly to the hitch by the weight of the trailer. In general, the maximum tongue-weight for a hitch is 10 percent of the maximum gross trailer-weight.
US Sailing Small Boat Course
Connecting the Trailer Most trailers are connected to the hitch with a coupler on the end of the tongue that slips over a ball on the hitch. The weight on the end of the tongue typically ranges from 5% to 10% of the combined weight of the trailer and boat.

BoatSafe.com
How do you measure tongue weight?
As a rule of thumb, the optimum tongue weight is between 5-10% of the GTW (gross trailer wt).

LoadRite Boat Trailers
(Item 4.) The tongue weight should be between 5% and 7% of the GVWR (GVWR=weight of boat, fuel, and trailer).
The tongue weight can be adjusted by either moving the axles on the trailer, or by repositioning the boat.

Reese Products - Hitches page
Showing authorized ratio of tongue to gross weights for various Class rated hitches.
Class III hitches used as weight carrying is rated up to 5000 lbs. gross trailer weight (GTW)
with a maximum trailer tongue weight (TW) of 500 lbs.

The industry's 5% guideline is likely for the smaller boats that would ride lower (behind the tow vehicle) than our Macs. IN MY PERSONAL EXPERIENCE with the 26X (your's may vary), 5 percent is too low but 8 percent is ample for the 26X. I'd posit that the Mac's freeboard justifies something above the lowest industry guidelines, which are stated in 'ranges' for very good reasons. There is no magic formula that mandates a minimum 10% tongue weight.

Frank C

Re: Brakes on tandem axles.

Post by Frank C » Sat Aug 23, 2008 4:31 pm

As demonstrated just above, there's no magic formula mandating a minimum 10% tongue weight. The original poster shows a 26X with Etech-60. That's well within Rogers original specs for an outboard. Thusly, it has been accomodated by the original axle positioning, the basic boat-trailer balancing.

By contrast, my boat has an overweight Suzuki-60. For that reason I always minimize the fuel load while trailering. Further, my standard procedure is to load all heavy items toward center and bow of the boat, rather than using the aft berth for heavy stowage. This isn't just a 'towing procedure' ... it's my standard procedure for best sailing balance.

Adding a second axle to Roger's trailer results in a suspension system designed for "carrying capacity"
of nearly 8.000 lbs (including tongue weight). It doubles costs, complexity and maintenance demands of the trailer, and it vastly over-springs the trailer. Ergo, the boat hull, and its fittings and contents (and the outboard motor) are hammered by excessively stiff suspension ratings for every mile it travels down the road. A heavy outboard hanging off the transom (well-beyond the trailer's end) is a particularly inadvisable load to be carried in such over-sprung conditions.

In most cases, owners choose a second axle to eliminate tail-wagging. Unfortunately, that's like killing mosquitos with a shotgun. Unless you're planning to tow at 90 mph (apparently, one of us does), the Mac's tail-wagging is solely a function of inadequate tongue weight, easily addressed by intelligent stowage. For those of us with heavy outboards that change the boat's trailer balance, there's still a better choice than adding that second axle. Moving the single axle aft by 6 inches, or shifting the boat that much forward on the trailer ... Either are probably simpler, more cost effective and more appropriate approaches.

Finally, for those who are hull-bent on tandem axles, you really should be scrapping Roger's axle.
Rather, you should just replace it with tandem 2,500 lb. axles .... just another lonely, sole opinion.

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Rich Walton
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Re: Brakes on tandem axles.

Post by Rich Walton » Sat Aug 23, 2008 9:28 pm

I am with Chip all the way. Best mod I did to my boat was a second axel to my trailer! I think that in order to remove all fear from towing add a second axel! DONT goof around with what other people say. ADD THE SECOND AXEL WITH DISC BRAKES! Have you ever heard any one sAY they wish they had one axel? or one set of brakes? I will let ANY ONE who wants to, try my trailer with both axels and brakes and drive around. then hitch up there one axel trailer and then telll me they like the single axel. IF that happens I will buy the Johnny BLUE!

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bscott
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Re: Brakes on tandem axles.

Post by bscott » Sun Aug 24, 2008 10:08 am

Thanks Chip and Frank--the capper on my opinion to go to the tandem was two fold. I like Frank, loaded my two 6 gallon tanks, narrowly averting a hernia, into the bow and drove a whooped out interstate to the lake at 65 mph. When we off loaded the boat I moved the tanks back to the stern locker, 2nd chance for a hernia. My new tank somehow seeped fuel into the boat--my wife was not happy for an entire week end :evil: When she is happy, everyone is happy :D and visa versa. :evil:

Second fold--on they way home, I left the tanks in the fuel locker (only used 3 gallons--total weight 60#). My wife asked me why the boat/trailer was acting "funny" at 60 mph. She is a chemist with a minor in physics. If my wife recognizes a problem, there is a problem :cry:
BTW, and edict from on high, no more fuel in the cabin. :!:

I'm not going into the math on how a mere change of weight of 90# additinal leverage in the bow VS 60 in the stern affects stability---it does to an uncomfortable extent. Seat of the pants matters.

The size and wight of the tow vehicle is an important factor. I have an 03 Grand Cherokee that has towed many trailers, many miles. It's frame/rear axle is plenty stout to trailer 5-6,000# load and the air bags can lift 400/500# tongue to a absolute level with 50# tire pressure.

I know that the tandem requires level towing. Frank, your observation that the springing is too stiff is excellent. I am removing one leaf from the original axle--maybe two and spring for a total weight of 6,000#. I am not going for the disc as it will drive the price beyoned the allocated 2 boat bucks. I do my own wheel and brake servicing so the tandem drums will work OK.

Chip, thanks for the dwgs, I have used sliding axles in the past so I can move the axles on the slider with the boat on it to get the exact tongue weight I want, factoring in the aero lift of the bow which is minimal considering it is in the draft of the tailgate. A little NASCAR lingo 8)

KHE had a wheel problem that could have wrecked his boat/trailer/truck/family lives---4 is better than 2---another quote from up on high. :idea:

And the BLING factor, priceless 8)

Bob

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