Spring poundage... ok for towing?

[Harvey]

Simple question this one... TJM springs are 180lb per sq inch. This is their HD version. My question is... is this enough for towing?

 

At the moment I tow with my Montero/Pajero/Shogun [depending on your country of origin] and this has uprated medium springs that sag about an inch when i'm loaded up. I tow my race car and equipment with it to the track and home again once a month. The rest of the time I usually have little in the car.

 

My trailor is approx. 800kg, my race car 800kg, my other race equipment another 200kg... + my wife and I and misc items. So overall I'd say fully laden the vehicle's additional weight over std would be approx. 2000kg.

 

Given the additional weight, I'm wondering if the rear springs at 180lb sq inch would sag heaps when i'm loaded up... the last thing I want is an unstable Paddy.

 

All thoughts and suggestions are welcome.

 

Thanks

Harv.

Edited September 14, 2008 by Harvey

[MY1PATH]

I'd say your vehicle is going to sag under load and an inch isn't very much. Unless your having handling issuses I don't see much need to upgrade. The weight you need to know about the trailor w/ reguards to springs it the tounge weight. This is the actual amount of weight that the trailor puts on the hich and the rest is distribuetd thru the wheels of the trailor.

[Harvey]

My1path thanks for your reply. It's a home made trailor that I have and so haven't a clue about what weight the trailor puts on the hitch. But, am I right in assuming that the longer the front 'A' part of the trailor [ ^ ]... he says trying to display it within the brackets... the less weight the trailor puts on the hitch and the shorter the A part = the more weight put on the tow hitch?

 

Also... am I right in thinking then, given your response, you think my std Pathy spring will be fine with what I am towing and there is no need to upgrade to the TJM HD option? Or were you referring to my Shogun re: that statement.

 

Thanks very much for your help. It is appreciated.

Harv.

[MY1PATH]

yes and no on the tounge weight, making A longer will increase your leverage and reduce tounge weight @ the cost of making your trailor longer (maneverabilty issues come mind) the position of the axle(s) in relation to where most the weight is on the trailor and the angle that 'A' comes from the axles are other factors. Your gemetry may already be fine as far as the trailor.

I did get a little mixed up between you montero and your pathy. I'd say try loading up the pathy and see. If it sags more than a few inches or gives you handling issues on a test run then upgrade. Keep in mind that the pathy is only rated to tow arround 3,500 lbs and if you think your tounge weight is over 450lbs I wouldn't try it. Hopefully somone with a little more expeice with towing and pathfinders combined will chime in.

[mws]

Sure, I'll chime in!

 

In general, you want your tongue weight to be at least 10% of the total weight to maintain stability. If tongue weight is too low, the trailer can become unstable under certain conditions and begin swaying back and forth (side to side). In severe cases, this instability can be severe and each oscillation gets worse and worse until the entire rig tips over or goes out of control. I've seen it happen, and it is frightening. There is really nothing the driver can do. Sometimes stabbing the trailer brakes (if electric with a controller in the cab) will snap it back in line, but that is assuming you can catch it in time. At some point, the whipping is so severe you won't be able to reach the controller...

 

A good sway control system will help prevent this, but will not do enough to save a really poor set up.

 

I really, really like airbags for towing. Airlift makes bags that fit within the rear springs. They work very well and do not cost much. When you need more load capacity, you pressurize them with compressed air and the load capacity is greatly increased. Properly installed and pressurized, it will bring vehicle back to level.