GideonKrynauw
Shocks, tyre pressures and towing 4x4 trailer on dirt roads
Hi there,

I need to start by thanking everybody that contributes on this forum for advice and guidance. This has most likely resulted in me becoming a big Pajero fan and every week I read all the forum updates. I also follow all the advice posted on the forum almost blindly! :D


Some background. I purchased a Pajero 2003, 3.2 did lwb GLS, 18 months ago and the car has done 215’000 km to date. I enjoy driving it and it is fantastic taking the family on holiday. It gives good consumption and is happy to cruise all day long at the speed limit. I was so impressed that I convinced my retired father to trade in his trusty Hilux KZTE double cab bakkie in on one too.

He purchased a 2005 spotless, lwb, 3.2 did GLS with only 88’000km that was in mint condition. He quickly got a second battery system installed, removed all the rear seats, installed a drawer system, hooked his 4x4 Camptec trailer and headed off for Northern Zambia through Zimbabwe all the way from Cape Town. It was in and around Mana Pools in Zimbabwe where we started complaining about the bad dirt roads and that everything is rattling. The roads were so bad that he had to replace the rear shocks when they entered Zambia (in Lusaka). They said the shocks were finished due to the bad roads and not coping towing the trailer…? Still does not sound like the Pajero I know...

Now the trouble is twofold. I feel guilty since I convinced them to trade the Hilux in on the Pajero and now they seem to be avoiding dirt roads if they think the road is not in a good condition. They love touring and is more on the road than at home. I think this is a shame since the Pajero was built to drive on these roads and I think it is particularly good on gravel roads in 4H.

I don’t think the fully loaded Camptec 4x4 trailer is particularly heavy and the Pajero is not too heavily loaded. I do think they have not deflated the tire pressures at all and was most likely driving with pressures around 2.2-2.5 bar over long distances and very bad corrugated dirt roads. This could be half of the problem. Surely the shocks should not fail at 90’000 even if the roads are terrible?

Any particular advice that I can give them in how to optimize the setup? Different behavior? Will airbags help?

Regards
GK
Davidvan
Re: Shocks, tyre pressures and towing 4x4 trailer on dirt ro
Hi Gideon,

From my experience and on very badly corrugated roads, I drop pressures down to 1.5 bar on the Paj and 1.2 bar on our offroad trailer. If road is just adhoc bad I got to 1.8 on Paj and 1.5 on trailer. Soft sand I also go on the lower side.

My rear shocks are ready for swap, but I have air bags in at current and very happy. Perhaps a few questions just to assist.

Does the Paj have standard shocks/Coills?
What tyres are currently used?
What were the real pressures of the tyres, some garage gauges are way of, and assuming long distance driving, pressures could have been rather high.

These can possibly affect comfort

Cheers

David
Re: Shocks, tyre pressures and towing 4x4 trailer on dirt ro
Also how sure are you that the shocks that were replaced in Lusake were really shot?
What was the test?
Wat were the symptoms?

I have towed a Chobe caravan on the worse corrigations that the Namibian craters can offer with my standard shocks now at 118000km. Yes it feels like the corrigations are sometimes breaking up your vehicle, but get back on the tar and all is forgiven. I find the Pajeros feel quite bad on corrigations but standup to it well given its quite hard but tough suspension.
Willie from Jo'burg
White Gen 3 SWB Pajero 3.2 DID
GideonKrynauw
Re: Shocks, tyre pressures and towing 4x4 trailer on dirt ro
Hi Bigwill and David,

Firstly thanks for the response. I can report back on the following:
In Lusaka they paid approximately R2500 for the two rear shocks (the same that I paid for 4 shocks in JHB!). I am not sure what brand they replaced it with, but as pensioners this is a big whack of money that could have been spend differently! To date, the car has got standard coil springs and shocks on and they started the trip with 4 brand new tires: Bridgestone duelers AT: 17” 265/65. Importantly, they did not drop the tire pressure at all, this would have been close to 2.7 bar for pajero and 2.3 for the trailer

The shocks were completely gone and could easily be pressed in by hand.....

Apart from the expensive lesson the trip is apparently fantastic, with many animals.

Thanks
Gideon
Re: Shocks, tyre pressures and towing 4x4 trailer on dirt ro
My first reaction is that the tyre pressures are way to high.

Use the 4PSI rule:
.... the 4PSI rule. It is a bit tedious, but once figured out, it works well.

4PSI = 0.275bar = 27.5 kPa

There are so many variables, such as tyres type and size, load, temperature, road surface, etc. that a blanket pressure does not always give the ideal answer.

The 4PSI rule works like this:

Tyres cold.
Choose a pressure.
Drive until tyres reach operating temp (the time/distance will vary).
Measure the pressure, and compare with the 'cold' pressure.
If it has risen by ±4PSI, it's correct.
If it has risen by less than 4PSI, the tyres are over-inflated.
If it has risen by more than 4PSI, the tyres are under-inflated.
https://www.pajeroclub.co.za/forum/view ... 4PSI#p3507

https://www.pajeroclub.co.za/forum/view ... 4PSI#p4312

https://www.pajeroclub.co.za/forum/view ... 4PSI#p3922

eg On my Gen1 I have large tyres (33x15) and on bad gravel I let them down to 1.1bar!
At 2.7bar I think the Pajero will self-destruct!
Gerhard Fourie
If you want to shoot somebody, make sure you aim at his head, not your own foot.
Me
Image
CFJ
Re: Shocks, tyre pressures and towing 4x4 trailer on dirt ro
Hello

Been in the tyre industry for 14 years,my advice to you is as follows
-Check tyre pressures when tyres are cold(not driven yet)buy ourself a presure gauge from autozone/midas -check it before leaving home.
-How full was trailer loaded(INFLATE tyres aggordingly for eg fully loaded eco trailer=-1000KG pump tyres 3.0bar
-Towing of trailer/caravan its advice not more than 80kg weight on the towing ball-check if trailer wasnt to heavy loaded in front
-Diffrent road condition diffrent pressures-manufactures of tyres say deflate starting at 10%
-Dont get confused the shockabsober work is to keep tyre to the road not carrying the load-work of coilspring/lev spring.
-What is life time of a shockabsober-difficult to say
*do visual inspectio on shock-check for oil-leaks-bushes and rubbers that has been worn.
*avarage lifetime i would recon between 80 000 and 100 000km you can start replacing ,yes there is people that got higher milleage.
*remember gabriel/monroe/old man/ens -piston sizes are bigger than oe shock on pajero
*best way to test a shock is takeing it out and press it down to see if its returning.-al of these testing machines you test coil spring with shocks

I hope this will help you,and i dont confuse you

CFJ
Re: Shocks, tyre pressures and towing 4x4 trailer on dirt ro
CFJ wrote: -How full was trailer loaded(INFLATE tyres aggordingly for eg fully loaded eco trailer=-1000KG pump tyres 3.0bar
Sorry, but I have to disagree.

The 'best' pressure is not a function of the vehicle weight only!
The following play a role as well:
  1. Tyre size
  2. Tyre construction (side walls, ply rating etc)
  3. Road conditions.
  4. Speed
  5. Ambient temperature
eg On the same vehicle (car / trailer) with the same weight but the following tyre sizes, the 'best' pressure can definitely NOT be the same:
  1. 29x8x15
  2. 33x12x16
The contact areas differ substantially, so the pressure has to be different as well.
Gerhard Fourie
If you want to shoot somebody, make sure you aim at his head, not your own foot.
Me
Image
paw_by_paw
Re: Shocks, tyre pressures and towing 4x4 trailer on dirt ro
I think all in all said- tyre pressures, loads and type must have a huge impact on handling whether dirt badly corrugated or rocky terrain. Badly corrugated roads will play havoc on any vehicle bakkie or not.
The best is trial and error. Use the 10% rule and work down from there. We all know that in sand it is a different story with low as possible without risking tyre spinning in the rim.
I tow a Off Road caravan and in almost all dirt road conditions go down to between 1.5 and 1.7 bar depending on my load and road conditions- I start with higher and drive a few km's to establish road holding and comfort and work from there. With towball weight on the rear I use 1.8 to 2.0 bar on the bakkie and my Gen 2 Pajero never above 2.0 bar and almost same for front as the Gen 2 will most certainly "ruk" apart due to no coils but only shocks and torsion bars.
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