Handling problem - Help!

[surfer4life]

So there's good news and a fair bit of less good news...

Good stuff first. Dropping the tyre pressures made a big difference to the handling. It's still a little floaty at the back but not a worry any more and the ride is much improved as well. Not a surprise having found out I'd over inflated by about 80%!

Also the re-mapping guy got the map done and said it was now pulling hard even in 5th! Hooray!!!!

Not so good stuff:
- The mapper guy could not get the map permanently uploaded to the ECU. I'm going to have to take the ECU out and either bring it to a guy in Belfast or post it to another specialist in the UK
- Mapper guy also said that the left front brake calliper was not working properly and he's correct - it's pulling to the right. Hopefully just a cleaning job. I profoundly hate cleaning brake callipers
- I also regularly checked the tyre temp on the way home this evening. Just in case.... and found that the rear passenger hub was getting too hot. So I probably have a binding brake. Argh! Another one to try to clean.


Also I'm pretty confident I will still need to replace the shocks. I've tried Koni and they do not appear to have options. Any suggestions?

let me know if you fix the rear hub heating issue, i still haven't fixed mine on the drivers rear and i'm due to goto EIRE on a surf trip in few weeks!

 

[ianc]

Surfer4life - Hub heating problem has been solved by ....... Well ignoring it! I've confirmed that the rear brakes are not binding (parking and driving), so that's not causing the heat build up. The ESB mechanic (who works on these vehicles all the time) told me the reear hubs always generate a fair amount of heat.

 

[Arfur's World]

I noticed that with Arfur when we were putting the miles on around France. Quite often when you stop for a snack, you can smell the hubs. Then it was made even worse because it turned out my left rear caliper was stuck off, so the right pads went through in no time driving round Corsica MB dealers in France are not the cheapest! Over £300 for new pads to be fitted and the caliper released, but it got us round the rest of the tour, I'll need to service the calipers when I get the chance.

 

[ianc]

Apparently Varios do have a problem of sticking brakes on the back and one of the consequences is that they fry the hub bearings. It's one of the things I was warned to check when I was buying. The mechanic told me to walk away from any which had the wheel nut tell-tales melted or missing. If you could smell the hubs, then they were getting a lot hotter than mine.

 

[surfer4life]

happened a couple of times to mine where the hubs (or brake calipers/discs etc...) was so hot my tyres where smoking and i thought it was gonna go on fire, still havent sorted it yet and its always in the back of my mind on any long journeys!

 

[theburtseoni]

Just a thought or two on your handling issues . . . . I have had both single rear tire and dual rear tire axles on different one-ton domestic US trucks and can tell you that having duals gets rid of alot of sway in the tail end when packing a lot of weight. I read on the forums that the Aussies usually replace the rear dual tire setup on thier Mitsubishi Fuso FG4X4 trucks with single rear tires so that the rear axle tires will track in the same line as the front axle tires. That works well when in deep mud, snow, or very narrow off road situations. But when going at highway speeds with a heavy load, the duals sure do get rid of the sway in the rear end. If most of your driving will be slow and alot of it will off road, then singles are the answer. But if mostly you will be on hard surface roads at higher speeds, then you may want to go back to duals.
Over here in the US alot of the younger folks who buy the surplus US military 2.5 and 5 ton trucks like to put on the big super single tires all the way around, they figure it looks really cool- and the big single tires do look nice! But the old timers who have any experience in the real world will always put duals on the rear axle or axles because they get rid of sway and can pack the heavy loads without feeling like the rear end wants to come up and join the front when going down the hard pack or paved roads at higher speeds with heavier loads! :ylsmoke:

 

[ianc]

Just a thought or two on your handling issues . . . . I have had both single rear tire and dual rear tire axles on different one-ton domestic US trucks and can tell you that having duals gets rid of alot of sway in the tail end when packing a lot of weight.

I think you are right that the singles on the back are a major contributor to the rear sway. Though I do wonder why the 4x4 military spec trucks with singles all round don't appear to have this problem. Perhaps they do and people just don't talk about it....

 

[ianc]

The airbags were supplied and fitted by Matt Savage and are of american manufacture easy to fit due to plenty of room but require solid location on the upper spring leaf. I think and stress think that they act as extra damping on the front axle as well as the obvious advantages of giving adjustable axle movement and leveling when parked and on the move, I tried and failed fitting personally smaller air bags on the rear axle due to the limited space over the rear springs.I will try and post photos
Chris

Gentle push - Dragonsmaug. Any chance of a few photos of those front airbag mounts?
I spoke with Matt Savage and he offered to send me photos but then discovered he hadn't taken any close-ups or rather couldn't find them.

 

[theburtseoni]

I think you are right that the singles on the back are a major contributor to the rear sway. Though I do wonder why the 4x4 military spec trucks with singles all round don't appear to have this problem. Perhaps they do and people just don't talk about it....

You are so right! There have been many 'issues' and outright accidents with injuries and loss of life due to young inexperienced military drivers losing control due to handling issues with the large super singles instead of rear duals. Such things are not talked about unless you know the right channels to get that info. And too many civilian owned ex-military trucks with the large super single rear tires have had accidents or near misses when unknowing or inexperienced driver's overload, or under inflate the tires and try 'unconventional' manuevers which leads to 'loss of control' issues.
Now if a truck comes from a manufacturer with duals there is a good reason for it. It was designed for duals especially when packing a load. To go to singles defeats the purpose and specific design of the truck, and handling issues will result. Some of these can be partially overcome with heavier single tires, different or heavier springs, air bags, sway bars etc and different (read: extra careful!) driving techniques.
US Military trucks were designed to travel at 45mph or less, pack heavy loads and be reliable. And the older 800 and 900 series trucks were designed with dual rear wheels, for a reason too! When the powers that be elected to go with the super singles the trucks worked when traveling at or under 45 mph. But with the larger tires, the young bucks found out that top speed also increased, and that's when the handling issues increased! :Wow1:

 

[Dragonsmaug]

Here are 3 pictures ,on the third I hope you can see where the bottom locating plate failed and I welded up in Mongolia.
Chris

 

[ianc]

Dragonsmaug - Perfect - Thanks. Very interesting to see that you have 4 leaf springs. Mine are only 2 leaf parabolics rated at 3000kg for front axle. What year is yours and what's the plated front axle max?

 

[Dragonsmaug]

Ian
1998 year and 2500 kg rated and I think that I have about 2300kg on the front at the moment. I found that the vehicle felt and I repeat felt unstable with less than 2200kg on the front but the load on the rear does not make a lot of difference its about 4000kg . I have just purchased 6 off 9.5 R17.5 tyres but it would be nice to swap some time to compare handling.
Regards
Chris

 

[charlieaarons]

My Unimog U500 camper has very large singles and does not have a sway/instability symptom. This is despite "only" 4400kg in the front and up to 81-8200kg in the rear. However, it was designed for the singles (395/85R20 XZL). It has a humoungous sway bar front and rear, 34mm coils in the front, 38mm in the rear (about 1.56x stiffer in the rear), Panhard rods, trailing arms, axle also located with the sway bars.
One fact which probably won't help you: if tires in the rear are slightly larger than the front it can cause instability. If the fronts are slightly taller the opposite is true - it stabilizes the truck. You COULD have the rears shaved down a few mm.

Charlie

 

[ianc]

Ian
1998 year and 2500 kg rated and I think that I have about 2300kg on the front at the moment. I found that the vehicle felt and I repeat felt unstable with less than 2200kg on the front but the load on the rear does not make a lot of difference its about 4000kg . I have just purchased 6 off 9.5 R17.5 tyres but it would be nice to swap some time to compare handling.
Regards
Chris

Interesting to hear about the feeling of instability. I have about 25-2600kg on the front axle. Happy to do a test swap of wheels if your ever near Dublin. I'm guessing you're still somewhere around the middle east?

 

[ianc]

It has a humoungous sway bar front and rear, 34mm coils in the front, 38mm in the rear (about 1.56x stiffer in the rear), Panhard rods, trailing arms, axle also located with the sway bars.
One fact which probably won't help you: if tires in the rear are slightly larger than the front it can cause instability. If the fronts are slightly taller the opposite is true - it stabilizes the truck. You COULD have the rears shaved down a few mm.

Charlie

Is that 34-38mm sway bars? They are 50mm on the rear and about 40mm on the front of the Vario!

The one thing that the Vario does not have and which might be a factor is a Panhard rod or Watts linkage. I don't know how effective the standard leaf springs are at locating the rear axle. Of course the Mog requires the Panhard rod because there's nothing else locating the axle laterally.