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-   -   1979 full sized bronco (http://www.airforums.com/forums/f463/1979-full-sized-bronco-45414.html)

bogie346 09-27-2008 10:28 PM

1979 full sized bronco
 
Hi everyone. I've searched the FAQ's/Archives before posting this request for additional info. I have a '79 full size bronco with a new 400cid motor, towing cam with matched valves, springs, lifters, new flat head pistons, heavy duty aluminum h2o pump, aluminum intake, oversized radiator, 20,000 lbs., transmission cooler, added oil cooler, etc. The truck weighs about 6400lbs. It is also equipped with a 10,000 rated tow hitch/equilizer bars. I've used the old airstream formula to determine the horsepower to weight ratio and seem to fall into the acceptable tow range for towing a '75, 30' landyatch AS. The dry weight of the AS is about 7200 lbs. I seem to have sufficient power to tow this rig but at 40mph/above, the AS starts to fishtail and sway dangerously side to side It becomes almost impossible to keep the truck steering in a straight line. The front suspension on the truck is new/tight as well as the steering components. Is the wheelbase on this bronco just too short for the lenght of the AS? Would the addition of dual stablizer bars added to the hitch rectify this problem?? I also have a new and working brake controller on the tow vehicle. The AS brakes/tires are also new and functioning properly. Would appreciate any input as there are too many horror stories about mismatched tow vehicles and trailers. Thank you for any suggestions. JK

ROBERTSUNRUS 09-28-2008 01:13 AM

Welcome to the forum.
 
:) Hi, bogie346. I would just say that the Bronco wheel base is way too short for towing almost anything yet alone a 30'er. You might be able to tame it down some with a Hensley Arrow hitch, [considered a cure all by some] but I wouldn't do it. My experience with these Broncos is that they tend to wander enough by themselves without the added help of a trailer being connected to them. [my opinion]

ROBERTSUNRUS 09-28-2008 01:47 AM

Mexray towed with a Bronco.
 
:) Hi, I just noticed that Mexray towed a 29'er with a Bronco, but now uses an Excursion. Maybe Mexray will chime in with some real world experiences.

Lumatic 09-28-2008 02:36 AM

You could add sway control bar(s). Also have you checked the alignment of the trailer running gear? But a lot of people say the wheelbase of the TV is just too short.

AlbertF 09-28-2008 05:38 AM

There's a fellow who posts regularly over on the RV.net forums who previously towed a large popup with a 1970s Bronco. He now tows with Freestar and frequently comments on how the Freestar is dramatically better as a tow vehicle.

It's not just the short wheelbase, but a high centre of gravity and a suspension system and probably tires optimized for off-road driving, not towing. What size/type tires are on the Bronco now? If they are wide, soft 33" tires, you will want to consider replacing them with narrower, stiffer LTs. A pair of friction sway controls will help, but you should have a stable setup to begin with and use the friction controls as insurance. Hitch setup may need fine tuning, but I'd guess that in the end a Hensley or equivalent may be needed make this combination work properly.

Excursions can have stability problems too; numerous owners have modified the rear suspensions with Helwig sway bars to keep things under control.

CanoeStream 09-28-2008 05:49 AM

This sounds like more than an antisway issue but I'd still recommend excellent modern antisway with this rig combo.

Have you done something to redistribute load within the Airstream that might lighten the tongue weight? Did this have a gut and remodel? The whipsawing you describe could be too light tongue weight. Normal range of tongue weight is 10-12% of trailer gross weight. Therefore you should see a tongue weight no less than 720 pounds with the trailer empty. And don't put heavy gear behind the axle. There's an easy tongue weighing technique in your trailer manual -- or it's explained here.

Saying "10,000 rated tow hitch/equilizer bars" leads me to believe you have weight distribution bars.

Diesel1 09-28-2008 07:50 AM

Check your tongue weight. Make sure it is 10 - 12% of your trailer gross. I have encountered this same problem with a short wheel based 1969 F100 towing a tongue light trailer. Very spincter puckering!!!

digger bear 09-28-2008 08:16 AM

Similar to your Bronco. I have a ramcharger - 360 rv cammed rodchester 850 4BB. It will climb trees- and - move my AS no problem (I do use it to park my baby) - but - the wheel base is too short and center is too high. Just like your bronco its great for a lot of things but not towing. For the safety of your family - get a long wheelbase to tow. IMHO I tow with a long bed cummins.

safari 28 09-28-2008 09:40 AM

I read this quickly and did not see any refrence to weight distribution. You must use a reese dul cam or the like to control sway and transfer weight to to the front axle. Your problem will be the stiff front axle and its ability to accept weight. It would be interesting how this would help your control problem, Towing just on the ball is not going to work. Go to a reputable dealer, you can find a used dual cam reese for cheap and this will in my opinion make a world of difference. Make sure the bars are bent, using 4-5 chain links and you see some lowering of the front axle of your truck. Good luck.

Road Ruler 09-28-2008 10:56 AM

Here is the Ford spec sheet on the old Bronco... Page Seven

It shows a 104" wheel base.

Don't leave home without "The Orange".... Hensley Arrow - Trailer Towing Safety

Mexray 09-28-2008 11:35 AM

Yes we towed our 28 ft AS with our 89 Bronco for a couple of short trips...but it was an interim set-up at best...we have stock type 31 inch tall tires...it's a 302 engine, but I've installed 4.10 gears in the diff's...it towed at speed OK in the flatlands, but suffered when we got to the hills...like I said, it was only a stop-gap TV when we first got our AS.

We didn't have any 'sway' problems, I believe the tongue weight was in the proper range, and we also have a friction type anti-sway bar hooked to the standard Reese type WD hitch.

I only ran up to 55 MPH speeds, and really had to keep my attention on the road...that short wheel base just isn't designed for longer trailer towing...any panic situation would have found us in peril, due in part to the lack of brake capacity in the Bronco.

I wouldn't recommend such a short wheel base TV for any long term use...just isn't stable enough!

We found a great deal on an 4x4, 2001 Excursion Limited with the V-10 engine, and couldn't be happier! The 'X' is a big, heavy, stable TV for our AS...it's the difference between a destroyer and a battleship in stability! With it's 3/4 ton pickup chassis, V-10 power, and large disk brakes all around, it runs like it was made just for this job of towing our AS. Sure it gets just under 10 MPG, towing, but hey, it's really comfortable, and gives us a place to lockup our extra stuff in the back...:D

ronstory 09-28-2008 11:41 AM

Bogie346--

With all the mods to the engine... did you make mods to the suspension, driveline, tires? I have a 76' IH Scout II and have made major engine mods similar to yours and minor suspension mods (2" lift and 31" tires). The scout will get me to every location I desire for tent camping... but I would never tow with it.

My two cents.

Silverhobby 10-07-2008 07:33 AM

I towed a 25' Avion for many years with a 1979 Fullsized Bronco. I also used a Reese Dual Cam sway control and equalizing bars. Towing was acceptable, but I'll have to admit, it was "marginal" at times. I tried towing a 28' trailer and knew immediately, a bigger TV was needed.

n7bdl 10-07-2008 08:01 AM

I used to tow a 24' enclosed car trailer (about 7000 pounds) with a 1978 Bronco. It had a 460 transplanted into it, so had plenty of power. I had the same problem as you described. The Bronco was just too short. I did get a Hensley hitch, which seemed to solve the problem, but you still needed to pay close attention. The Bronco was only a half ton rated vehicle. I soon changed to a Dodge 3/4 ton truck and was much more comfortable towing.

Terry


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