It's relevant to situations where the tail starts wagging the dog, so to speak - the trailer sways side to side and starts yanking the rear of the tow vehicle around. Or pushing it around. Part of avoiding this is correct tongue weight vs. trailer weight, usually tongue weight should be 10-15% of total trailer weight. There's other factors like the one you mention. Here's an article on it from GMC: https://www.gmc.com/gmc-life/trucks/why-tongue-weight-is-important-for-safe-... But even a big heavy tow rig can get whiplashed by a poorly balanced trailer. I once rented a big beefy tow-equipped Hertz full size x-cab pickup to help my brother move his 22' Airstream (no suitable tow vehicle in the family stable). Not that huge a trailer for such a truck. But it turned out I couldn't go over about 52-53 MPH because the trailer was poorly balanced. Tongue weight was probably too light or too heavy, too light my guess. Edge up towards 55 and it would start to sway side to side, doing its best to take the rear of the truck with it...scary. Towing my M17 at the upper edge of my vehicle's ability, I definitely checked my tongue weight to make sure it was in the 10-15% range. cheers, John On 7/9/19 1:54 PM, Gail Russell wrote:
I am a total know-nothing on this subject, but from my acquaintances in the horse trailer towing world, I have been told that the wheel base length of the tow vehicle versus the weight of the tow vehicle is important. I presume this is relevant in a potential jack knifing situation, and is the problem when I am following a rig where the trailed vehicle is swinging from side to side.
Gail in Forestville CA
On Tue, Jul 9, 2019 at 1:13 PM John Schinnerer <john@eco-living.net> wrote:
Ditto most of this.
I am due for a brake flush and will spec DOT 4 to replace the DOT 3 that is most likely in there now.
If you are at all on the edge of your vehicle's towing capacity, and able to understand car talk (in general, not just the NPR show :-), the part about online forums is very applicable. For example my generation of subarus started in 2000, but the first year had significantly weaker brakes than 2001 and later. In other words not all vehicles of the same 'generation' in car maker terms are equal. I found that out on forums...obviously Subaru is not going to crow about it themselves.
Re engine temps, you want to keep your engine oil temp at 210-220F or below. Most cars don't have oil temp gauges (not with numbers on then anyhow) but if you have a new enough car as he says below you can get that info via added technology. Synthetic oils (if you are using them) may not break down as much above 210-220F as standard oils or blends, but in any case if your oil is above that, your whole engine is getting too hot even if the oil is not losing its lubricity. Coolant temp is not necessarily as good a measure as oil temp since various cooling system issues can give a low or normal reading on coolant temp when in fact you're overheating.
Re hitches, for an M17 or an M15 towed by smaller vehicles, for those smaller vehicles you will most likely find spec to be a Class II hitch. These are rated 3500 lbs towing and 300 lbs tongue weight, 1000+ lbs more than even a loaded M17 on trailer. They have a 1 1/4" receiver. They attach to the vehicle frame, not just to body metal. For example this is the one I put on my subie:
https://www.etrailer.com/Trailer-Hitch/Subaru/Outback+Wagon/2001/36284.html?...
If you have a bigger heftier vehicle then your normal spec will be a Class III with higher weight limits, also bolts to frame, and a 2" receiver.
If you have an M15, which you can tow with a smaller car than an M17 for sure, then your vehicle spec hitch might be a Class I, 2000 lbs max tow weight and 200 lbs max tongue weight. That is plenty for an M15, and properly made Class I hitches also attach to the vehicle frame not just the body metal.
In other words, go with a hitch that is spec for your vehicle. That keeps you in a reasonable safety zone. Assuming you don't overload both the hitch and the vehicle that is... :-O
Any decent hitch from Class I up will attach to the vehicle frame, so as he says below avoid anything that just attaches to body metal (including "bumper hitches" on small trucks and similar).
cheers, John
On 7/7/19 1:43 PM, casioqv@usermail.com wrote:
I wanted to mention a few things about towing safely with a light weight tow vehicle:
1. Change the brake fluid annually or less with a high boiling point fluid, especially if you have an unbraked trailer. As it absorbs water, the boiling temperature lowers rapidly, and will cause you to lose braking coming down a grade. I personally prefer to use ATE TYP200 which is a racing fluid, and boils at 536F dry and 388F wet (e.g. after about 2 years). If your car has several year old DOT 3 fluid, it could boil at temps as low as 257F, and lose all braking ability when the brakes aren't even very hot yet. Cars that take DOT 3 can use DOT 4 instead, which usually has a higher boiling point. Good ceramic brake pads and new racing grade fluid will drastically increase the braking capacity of any car or truck.
2. Find the online car forum for owners of your car model, and read everything they say about towing safely- weakness, modifications, etc. Often some car models will need a few things like a different transmission fluid, different rear springs, or different brake pads to overcome minor design flaws and make towing safer.
3. Most cars nowadays have temperature sensors on everything, but they don't report this data to the driver. With a bluetooth OBD-II dongle, and a smartphone app like Torque, you can get an audible alarm long before the transmission or engine overheat enough to cause permanent damage... whereas once the dash lights come on it's usually too late. As a rule of thumb, an engine should stay under boiling, e.g. 100C/212F when climbing a grade if the cooling system is in good shape.
4. A Class III 2" receiver hitch is worth it even for a small car with a light trailer. If you can't find one, you can get one fabricated by a welder. The cheap draw-tite, reese, etc. Class I hitches that just mount to sheet metal are unsafe, as those mount points will fatigue and fail if you tow a lot, even with a light weight trailer.
Sincerely, Tyler
-- John Schinnerer - M.A., Whole Systems Design -------------------------------------------- - Eco-Living - Whole Systems Design Services People - Place - Learning - Integration john@eco-living.net - 510.982.1334 http://eco-living.net http://sociocracyconsulting.com
-- John Schinnerer - M.A., Whole Systems Design -------------------------------------------- - Eco-Living - Whole Systems Design Services People - Place - Learning - Integration john@eco-living.net - 510.982.1334 http://eco-living.net http://sociocracyconsulting.com