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  Trailering with a tandem axle and brakes increase the towing capacity?

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Author Topic:   Trailering with a tandem axle and brakes increase the towing capacity?
SuburbanBoy posted 08-14-2002 11:37 PM ET (US)   Profile for SuburbanBoy   Send Email to SuburbanBoy  
Does trailering with a tandem axle and brakes increase the towing capacity?

I was daydreaming (again) about a larger boat and the requirements for safe towing. Does the addition of a second axle (tandem) with brakes change the capacity of the tow vehicle (due to the supplemental braking capacity), and perhaps reduced tongue loads (because of four tires). It is clear that there is a safety measure if one tire would suffer a blowout, but if one of my tow vehicles is rated at 1,500 lbs, could it safely tow say, 3,000 lbs here in flatland?

What do you think?

sub

lhg posted 08-15-2002 12:12 AM ET (US)     Profile for lhg    
Sub - I think the answer to both of your questions is "no".

Tongue load is tongue load, and should be 5-10% of total load. As you know, with either type of trailer, it is a necessary evil to prevent fishtailing.

Trailer brakes do not increase a vehicle's tow RATING. But they do allow you to reach a vehicle's tow rating, if it is high enough, such as over 3000lbs. For instance, my Caddy has a 7000# rating, but without brakes, it would only be safe to tow about 3500#'s, and even that could be over some state's laws on brakes. No way could I tow 7000# at highway speeds without brakes.

I also think, however, that some vehicles can safely tow more than their advertized rating, if they are FRAME based, rear wheel drive rather than Unibodied front wheel drive. Brakes could help here, but be careful, so you don't have the "tail wagging the dog".

Jay A posted 08-15-2002 12:20 AM ET (US)     Profile for Jay A    
Whatever your vehicle is rated to tow, that's it! It doesn't matter if it's a tandem or a single. The advantage of a tandem trailer is better distribution of weight. the real advantage goes to the trailer itself, less stress for the hubs/bearings in a tandem trailer and a better ride. Also tongue rating will differ depending where the center of gravity is located due to the position of the boat. My 13' Whaler was positioned in a way that I could pick-up the tongue with my baby finger! On the other hand,My 21'Seapro with a tandem trailer, I must use the tongue jack. If you plan to tow 3000 lbs with a 1500 lbs rated vehicle, make sure your AAA is paid up! I wouldn't want to try to make an emergency stop with that set-up, You might be wearing a boat!
SuburbanBoy posted 08-15-2002 12:46 AM ET (US)     Profile for SuburbanBoy  Send Email to SuburbanBoy     
LHG,
Holy Moley!, 7,000 lbs. towed by a Caddy! Must be an older model. I checked on a Ford Crown 2002, and I was told to buy a Explorer if I wished to tow anything. I have since discovered that the Escape is good to 3,500. But a car wiht a capacity to tow 7,000 lbs. is great.

My factory hitch mount is extensivly reinforced where it is mounted to the unibody, with the system rated for 1,500 lbs. I have noticed that there are aftermarket systems available for the same vehicle rated at a higher capacity... Hmmm, but they do claim 3,000+ lbs. I suppose it is better to meet the mfg's spec's.

sub

SuburbanBoy posted 08-15-2002 12:57 AM ET (US)     Profile for SuburbanBoy  Send Email to SuburbanBoy     
More random trailering thoughts...
There is probably some obscure rule of thumb regarding mass of towing vehicle vs. mass of boat/trailer combination. It ain't 2:1 or even 1:1 as I can't imagine LHG's Caddy topping the scales over 7.000#. So if I have brakes, and my vehicle weighs more than the towed trailer, where is the beef?

I bet I could hang my vehicle from it's hitch, so that is not the weakest link. The trailer brakes help to increase braking capacity. I wonder how these mysterious ratings are arrived at.

I guess I will have to hang-in-there for my elder Crown Vic Station wagon to become available. I don't think it will pull 7,000#. I remember a picture of LHG's rig. It was pretty intimidating to a small car guy. It never really registered that it could drag 7,000# around.

sub

EddieS posted 08-15-2002 02:03 AM ET (US)     Profile for EddieS  Send Email to EddieS     
SuburbanBoy,

I alway thought you chose your handle because you drove a Suburban! There are many factors that play into a vehicles towing capacity. Most have to do with the drive train, gear ratios, manual vs auto trans, axle rating to name a few. Not all tow vehicles are created equal even with the same tow rating. In general you are better off with a full size vehicle for pulling the heavy loads, personally anything over about 4500 lbs I would not even consider using a smaller vehicle. I am not saying it cannot be done, just not by me.

I pull my 16 with my f150 and there have been a couple of times that I was thankful for the antilock brakes and the stopping power of my truck.

Ed

lhg posted 08-15-2002 02:34 AM ET (US)     Profile for lhg    
Sub - I doubt if anybody else here is interested, but Cadillac offered the 7000# tow package, consisting of all sorts of goodies like HD trans cooling, HD radiator, high capacity alternator, positraction 3.70 rear end, 350 Chevy engine, etc on the big rear wheel drive Brougham models from '91 through 1996. These were the biggest passenger cars on the street. '94-96 are the best, since they had the higher hp Vortex engine, same as the Impala Super Sport, all made at the same Arlington TX plant. My Caddy mechanic tells me the car's drive train is basically the same as a Suburban. But it doesn't have the truck suspension, and hence requires the weight distributing hitch. I have towed my 25 Outrage close to 100,000 miles with one of these beasts! The package was special order, and they are now hard to find used, but are out there. GM hoped this model would catch on with the towing crowd, but didn't. Most still prefer the trucks, which don't have the engine choked up with pollution controls. I've never seen another one towing a boat.

I think towing capacity is more related to the frame design of the vehicle, and strength of the drive train components, especially the rear axle and it's ratio.

When I tow my 18 Outrage with this car, I don't even know it's there! The long and low wheelbase of the car is great for towing stability.

But everywhere I go, guys are continually amazed at the size of the 25 relative to the car. Often the car gets more attention at the ramp than the Whaler.

SuburbanBoy posted 08-15-2002 08:24 AM ET (US)     Profile for SuburbanBoy  Send Email to SuburbanBoy     
Over the last 10 years, Whalers (as have myself and average Americans) gained weight. Because of this increase in weight, potential customers perhaps have had to limit their choices. When the 18 OR was manufactured in the 80's, I believe the average American car was capable of towing about 3,500 lbs the weight of an 18 OR rig. Today, it seems, the average American car could only tow the 13' Classic or smaller. We have to own a truck to tow most of the family sized Whalers. I have nothing against trucks or SUV's, but I personally enjoy driving, and the ride characteristic of a sedan are more to my liking than most of the truck dynamics available in the market. The mileage and upkeep of a sedan is more to my taste as well. I am not as lucky as some, and cannot use my Whaler on a regular basis. Towing is low on the list of vehicular duties in my household. Therefore, I will someday, perhaps pick-up a classic American family sedan, (or station wagon), with an eye to it's main purpose, the, towing of my (hopefully) larger Whaler. I have a “reservation” on a late 80’s Ford Crown Vic wagon, ordered from new with towing package, supplemental engine and transmission cooling, larger brakes, etc. I will certainly report out it’s arrival when and if it comes available.

SuburbanBoy was a name given to me by a long forgotten girl back in HS (she was class of 1968 or so, and “much” older than I). She was visiting from rural Minnesota, and found my behavior to more “suburban” than that of her friends back home. I was involved in sports, academics, boats, cars, girls, stereos, and other mischievous boy type activities. Perhaps the options in her hometown were more limited. It seemed to her that I always had something going on, and she was amazed that I did not just hangout and concentrate on just one of the previously mentioned activities, like other “men” in her acquaintance back home. Anyway, my HS chums thought that her nickname for me was a hoot (as did I), and continued to refer to me as Suburban, or Suburbanboy. I have shortened it to sub. I use it here as I consider this group to be loosely similar to the diverse group of friends and acquaintances I had back in the 70’s. It is also easy to type quickly.

sub

Swellmonster posted 08-15-2002 09:43 AM ET (US)     Profile for Swellmonster  Send Email to Swellmonster     
I always try to get police package vehicles for towing. Everything heavyduty, coolers, suspension, brakes. "crown-vics)
I just got real lucky lately, now I have a police package tahoe (rare)
lhg posted 08-15-2002 03:55 PM ET (US)     Profile for lhg    
Regarding the BW weight gain, it definitely is affecting one's ability to tow the larger Outrages, no matter what the vehicle.

In spite of it's size, the Classic 25 Outrage is quite light weight (3300 lbs) without a lot of fuel on board, and not difficult to tow and handle at a launch ramp. But it's replacement 26 Outrage and now 270 Outrage, are a LOT heavier (1700 lbs + heavier Opti engines), and pushing the limit for towability. I have already decided that I would never attempt to tow a boat as heavy as those are, and I have never even seen one on a highway. So in reality, the marketability and flexibility of these boats has been reduced. In my book, this is too much to give up for a smoother ride into a chop & higher fuel consumption costs.

quattro20vt posted 08-15-2002 08:40 PM ET (US)     Profile for quattro20vt  Send Email to quattro20vt     
first post...I'm a 10+ yr boat owner...brand x (owns BW, BTW), but looking to move "up" (ironic, huh?)

Interesting thread, hits a nerve for me here...i'd posit that a lot of "conventional wisdom" on towing is mostly right, but forgets the politics of our litigious society. I'm guessing most car manufacturers, knowing the towing intelligence of average drivers (certainly not folks on this board!), limit their exposure to incidents & liability by dropping tow ratings to nominal levels.

I've got an 18' Searay 180BROB, Merc 135, on a braked EZ-Loader trailer. rolling weight with fuel, about 2400#. For years, I towed it behind a 2800# Audi 4000 quattro--AWD, 115hp, stump-puller 1st gear--great tow vehicle with a 2000# tow rating. not legal, right? Today, I tow behind a Volvo 940 turbo wagon--3200# car, 162hp. IMO, an inferior tow vehicle with only RWD, but legal with a 3300# tow rating.

What changed? well, I traded my old Audi (new car didn't have hitch), got older, gained a few more things to lose...there's a legal theory some plaintiffs pursue where, if you have violated some law intended to safeguard you and others, and you are involved in an incident, you are presumed to be at fault.

All that said, I might consider using my Audi 200q as a tow vehicle in the future, esp if I get a bigger boat: 3800# car, AWD, lots more power and torque (turbo), and a 2000# tow limit...oh wait. that's in the US. In Europe, my car is rated to tow 4400#.

go figure.

SuburbanBoy posted 08-16-2002 01:27 AM ET (US)     Profile for SuburbanBoy  Send Email to SuburbanBoy     
No kidding Quatro! Good idea, I will check the Euro versions of my vehicles for a dramatic capacity increase.

I remember the first time I drove an early Quatro, it was raining and I was very impressed. I would guess it was around 1985 or so. It was a very well balanced package.

I will probably come back to the Ford... fake wood and all.

sub

SuburbanBoy posted 08-17-2002 06:39 PM ET (US)     Profile for SuburbanBoy  Send Email to SuburbanBoy     
The plot thickens. Thanks to quattro20vt suggestions, I checked the GB site for my car (2002 CR-V). They state the capacity as follows (for their 2,000 cc version, note that mine is larger, 2,400 cc or 2.4 litres):

Without brakes=600kg (1,320 lbs)
With brakes = 1500kg (3,300 lbs)

This would imply that there is a possibility that my vehicle could tow 3,300 pounds in GB safetly. I find it interesting that the "without" brake category is so close to our (USA) rating.

What do you think?

sub

jimh posted 08-17-2002 06:56 PM ET (US)     Profile for jimh  Send Email to jimh     
LHG's Cadillacs are quite a sight. That same HD package was also available in the rear-wheel drive Buick Roadmaster for a brief period (c.1995).

A few years ago we were vacationing in Wisconsin and bumped into a Roadmaster with a triple axle trailer hitched to it. The owner was out boating, so we couldn't see the boat he was hauling, but we were very curious--a Triple Axle Trailer!

As our luck would have it, a few days later at another ramp (Bayfield, WI), he saw the same Roadmaster backing down the ramp and launching a huge I/O Express Cruiser. It must have been in the 25-26-foot range. Yup, he hauled it with the Roadmaster without problems.

I do think the Cadillac is a nicer looking car, however.

Lagged posted 08-18-2002 09:19 AM ET (US)     Profile for Lagged  Send Email to Lagged     
My FreeLander can toe 1.7 tons without trailer brakes, and 4.4 tons with them.
Dunk posted 08-22-2002 06:56 PM ET (US)     Profile for Dunk  Send Email to Dunk     
Didn't those Caddies and Buicks have vette engines in them. A friend lent me his Fleetwood Brougham to go to Maine in a couple months ago. I could believe the ass that thing had. It just bury's you in the seat when you stand on it. The owner's manual I think said 280hp and it still got over 20mpg. He wants to sell it. It's 95 with 55,000. I've been thinking about buying it. It's jet black, real mob wagon.
lhg posted 08-22-2002 07:21 PM ET (US)     Profile for lhg    
Dunk - the '94-'96 have the Chevy Vortex 350 engine, dual exhaust, etc engine. Same as the Impala Super Sports of the same years. My '96 indicates 300 HP.

The code "V4P" 7000lb trailer towing package gives the car the 3.70 rear end, same as the Impala SS has. Yes, these things are sleepers and will really move out, as does the Impala SS, which is only a few hundred pounds lighter.

If you want that '95 for towing, check the trunk assembly sticker to see if it has the "V4P" listed. If it does, you're in business. They are rare, however. Even without the package, I think they will easily tow 3000#. The fans are also a give away. The trailer towing models have the HD clutch fan, while the regular ones have the dual elctric fans, for less HP drag. If you really want one, go to a good Caddy Dealer, and have him let you know when one comes in on trade. You may have to wait a year or so until one shows up.

Jerry Townsend posted 08-22-2002 08:03 PM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
I am not aware of, and doubt that a 'generic' rule of thumb exists regarding the weight of the tow vehicle compared with the weight of the towed load. The reason - the dynamics of the vehicle/load combination depends on many things in addition to the weights - including wheelbase dimensions, trailer hitch to axle length, location of the c/gs of the vehicle and of the towed load, tire structure, et.al. Many of these parameters are unknown to the user.

In addition to not exceeding the hitch ratings, I would suggest the tow vehicle should be be at least as heavy as the towed load and have as long of wheelbase as possible. The tow vehicle should be the controlling component - not the towed load.

Also, some are using extensions of various lengths with some hitches - to extend beyond campers etc. Those using such extensions must realize that the hitch ratings are decreased when using the extensions.

I use a heavy duty 3/4 ton 4X4 GMC pickup for my boat (probably about 2500 lbs loaded) - but that is just my setup.

Frankly, all of you see vehicles that do not follow these guidelines everyday - the 18 wheelers on our highways - with the towed load vastly outweighing the towing vehicle, short towing vehicle wheelbase, et.al. They are normally stable and not a problem - until they hit the ditch, need to make a fast turn, or are on ice, particularily going downhill. From experience - in those cases, the color of the stuff changes pretty damned fast.

Regarding the effect of using multiple axles - as several have commented, the load rating of the hitch/tow vehicle is not changed. ----- Jerry/Idaho

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