Airbags on Std Suspension

[Harry230]

Happy to take OJ's advice, just was not sure whether the combination was correct for my proposed load. As per OJ comment he was happy to recommend a spring depending on my loading. Unfortunately that will be unknown until I get the caravan. But ballpark is known and the combo suggested may be fine.
I have PM'd "2slow" and hoping his feedback will help.

Also as per my last post "The KS site is a bit confusing as they list both a standard height and raised height under the KCRS-23, or is it the same spring that is standard height for Pajero and slightly raised for Challenger/PS"

Thanks all,
Harry.

[old Jack]

Also as per my last post "The KS site is a bit confusing as they list both a standard height and raised height under the KCRS-23, or is it the same spring that is standard height for Pajero and slightly raised for Challenger/PS"

Thanks all,
Harry.

Hi Harry,

Yes, you are correct with the King website being confusing and the KCRS-23 being listed as a standard height Gen 3 Pajero and a raised height Challenger/Pajero Sport coil. The difference between the Pajero and the Challenger is the position of the spare tyre is just rearwards of the rear axle and the fuel tank is forward of the rear axle on the Challenger/Pajero Sport where as the Pajero has a larger fuel tank mounted rearwards of the rear axle and a spare tyre mounted on the rear door.

King make a KCRS-33 which has a slightly lighter spring rate but the same free length as the KCRS-23 so the end results are almost identical based on my calculations. I have all the spring specifications on file from Kings and put these into a 1200 cell Excel sheet per coil that calculates the ride height at a certain total rear axle weight. It is accurate for linear rate coils but because Kings can not supply me with compression vs load graphs I can only calculate based on a lineal progressive spring rate change. Happy to send you through the comparison figures but due to file format and size it needs to be emailed.

OJ.

[2slow]

I have PM'd "2slow" and hoping his feedback will help.

Thanks all,
Harry.

Hi Harry,
Reply sent.

Hi OJ,
Its been awhile. Have swapped vans for one that weighs 220kgs on the ball, believe me it makes the rear-end drop.
Have purchased and am in the process of fitting an Andersen WDH but its taking a bit longer than it does in the YouTube videos. I'll get there eventually, I hope

[old Jack]

Hi Harry,
Reply sent.

Hi OJ,
Its been awhile. Have swapped vans for one that weighs 220kgs on the ball, believe me it makes the rear-end drop.
Have purchased and am in the process of fitting an Andersen WDH but its taking a bit longer than it does in the YouTube videos. I'll get there eventually, I hope

Hi 2slow,

With 220kg on the ball what are your front and rear ride heights?
My estimate is the front ride height will go up about 30mm with that sort of ball load, I would be interested in knowing the exact figure.
Also will be interested in knowing the results of the Anderson WDH and your impression of it as a WDH.
If you still think your rear coils are too soft then I can look at other brands as I think the next level up in Kings will be too high when you are unloaded.

Regards,

OJ.

[2slow]

Hi 2slow,

With 220kg on the ball what are your front and rear ride heights?
My estimate is the front ride height will go up about 30mm with that sort of ball load, I would be interested in knowing the exact figure.
Also will be interested in knowing the results of the Anderson WDH and your impression of it as a WDH.
If you still think your rear coils are too soft then I can look at other brands as I think the next level up in Kings will be too high when you are unloaded.

Regards,

OJ.

OJ,
I’m certain of the ball weight as I purchased a set of the scales required for that particular job. The 220kg is apparently the correct weight as the ball weight is supposed to be approx. 10% of the ATM (or GVM I can never remember which) for safety reasons. Seems very heavy to me but far more knowledgeable people than I tell me its right.

Have recorded the unloaded heights and will be hooking the van on tomorrow morning as we are headed for Cape Otway Ranges so I will get heights when loaded but it might take a little while for me to post them.

I did consider heavier coils but the ride (empty) is already very stiff and every bump is felt so I was concerned that heavier coils would only make it worse.

The Andersen WDH is a beautiful piece of engineering; the hitch welds and the lathe work on the tow-ball are exquisite. However I do need to make a coupler of spacers (not impressed) so that the brackets fit over the drawbar properly/securely then it will be fine I’m sure.

Greg.

[Sean11]

Hi Steve,

The Pajero Sport has much a different rear suspension than a IRS Pajero so what works on IRS Pajero doesn't work on the live axle coil suspension of the Pajero Sport/Challenger.

The Pajero Sport has identical rear suspension to the PB/PC Challenger and I have spent a lot of time working out what works and what doesn't for multiple applications. What suits an on road car with light loads is different to a car towing heavy on road and different again to one that ventures off road at GVM +. Many owners have used my suggestions and all have been happy with the upgrades they have done.

The PS like the Challenger has very soft progressive rate rear coils that do not carry weight that well and there are internal rubber cone helper springs for when the suspension gets some weight applied, but these are too short so their assistance is too late in the suspension travel and they only offer 75kgs of assistance before they compress solid..

So this is for a Pajero Sport that is not going hard off road, towball down load 220kg, using a correctly setup WDH and little weight in the rear seat or cargo area. This is not a full suspension upgrade but a rear only to improve the ride and load caring ability. 220kg on the ball is like 340kg in the back seat or in the forward section of the cargo area directly over the axle.


If you fit airbags then you lose the rubber cone helper spring assistance and this puts extra load and dependency on the airbags, this means if you have a leak and the airbag loses pressure you are worse off than standard suspension without airbags. Airbags will cost you between $300 and $500 + about $150 to $200 in labour fit. Personally I do not like to recommend airbags as a substitute for correctly rated springs and I think they are not good value for money.

l would recommend upgrading the rear coils to King KCRS-23 this is a progressive rate coil that has a ride height about 10mm to 15mm higher than a new factory coils (it does not take much load and time for the standard coils to sag) but has a 25% heavier loaded spring rate and a 10% heavier unloaded spring rate. I would also upgrade the rubber cone helper springs to Peddars PN 5899, these start assisting earlier in the spring travel, are softer initially and more progressive with a greater load assistance (at least double of the factory cone springs) before they become a solid bumpstop.
Coils will cost about $200 a pair, Peddars Cone Springs $125 a pair and $150 to $200 in labour to fit.
The end result will be a slightly firmer but much better controlled rear suspension that will pitch less and will not bottom out hard. You will not need to worry about leaking airbags and you should be able to reduce the tension settings on the WDH which is a good thing.

OJ.

Hi,
Just picked up a new PS and think about suspension upgrade to tow a camper, approx 200kg on the ball, so have read OJ advice above and it looks the the way to go!

Wondering if I can do this on the rear only, or if all have upgraded front suspension at the same time?

The vehicle is normally unloaded unless towing, and with 4 kids in the back most load will be in the trailer or distributed on the roof on trips.

Thoughts?

[Briggsy71]

Problem with Hayman Reece tow bar when tensioning WDH

Hi Steve,

The Pajero Sport has much a different rear suspension than a IRS Pajero so what works on IRS Pajero doesn't work on the live axle coil suspension of the Pajero Sport/Challenger.

The Pajero Sport has identical rear suspension to the PB/PC Challenger and I have spent a lot of time working out what works and what doesn't for multiple applications. What suits an on road car with light loads is different to a car towing heavy on road and different again to one that ventures off road at GVM +. Many owners have used my suggestions and all have been happy with the upgrades they have done.

The PS like the Challenger has very soft progressive rate rear coils that do not carry weight that well and there are internal rubber cone helper springs for when the suspension gets some weight applied, but these are too short so their assistance is too late in the suspension travel and they only offer 75kgs of assistance before they compress solid..

So this is for a Pajero Sport that is not going hard off road, towball down load 220kg, using a correctly setup WDH and little weight in the rear seat or cargo area. This is not a full suspension upgrade but a rear only to improve the ride and load caring ability. 220kg on the ball is like 340kg in the back seat or in the forward section of the cargo area directly over the axle.


If you fit airbags then you lose the rubber cone helper spring assistance and this puts extra load and dependency on the airbags, this means if you have a leak and the airbag loses pressure you are worse off than standard suspension without airbags. Airbags will cost you between $300 and $500 + about $150 to $200 in labour fit. Personally I do not like to recommend airbags as a substitute for correctly rated springs and I think they are not good value for money.

l would recommend upgrading the rear coils to King KCRS-23 this is a progressive rate coil that has a ride height about 10mm to 15mm higher than a new factory coils (it does not take much load and time for the standard coils to sag) but has a 25% heavier loaded spring rate and a 10% heavier unloaded spring rate. I would also upgrade the rubber cone helper springs to Peddars PN 5899, these start assisting earlier in the spring travel, are softer initially and more progressive with a greater load assistance (at least double of the factory cone springs) before they become a solid bumpstop.
Coils will cost about $200 a pair, Peddars Cone Springs $125 a pair and $150 to $200 in labour to fit.
The end result will be a slightly firmer but much better controlled rear suspension that will pitch less and will not bottom out hard. You will not need to worry about leaking airbags and you should be able to reduce the tension settings on the WDH which is a good thing.

OJ.

Hi Jack. I have read several of your posts and would welcome your experienced opinion. We are currently 450 km from home and what started as a rattle noise which seemed to be in the luggage in the back of the car, developed into more consistent and louder knocking scraping noise in the rear section of the car. We thoroughly investigated in and under the car several times and bounced up and down on the hitch. In doing so we located the source. We believe it is coming from the cut out in the bumper where the Hayman Reece tow bar protrudes, rubbing on the square tube. When we released the torsion bars the gap had increased . That being the case, it is moving within the gap. Loaded there is a gap of a couple of mm but when the torsion bar is released the gap is 10 mm. I was under the impression that the clearance should remain consistent.
We are driving a 2018 Mitsu bishi Sports and towing a 2 yo Coromal Element 612 with towball weight of 150 and tare weight 2086.
The GTM is 2370 with ATM 2890.
The readings taken of the car wheel arches diimensions were duplicated after leveling and 6 links were used to achieve this.
When the caravan is connected there is a change in height of approx 50mm.
All bolts were checked and found to be tight.
We visited some businesses today as we are not prepared to tow until this is sorted but we got a lot of conflicting information. Some suggested airbag and spring combination to assist the WDH from having to be so tensioner up. We are even considering changing to the ugly Mitsubishi regular tow bar.
We would welcome your view on this.
Peterb

[old Jack]

Hi Peter,

Welcome to the forum even if it is under the conditions that you have described.
My comments are in your post below in blue font.
OJ.

Hi Jack. I have read several of your posts and would welcome your experienced opinion. We are currently 450 km from home and what started as a rattle noise which seemed to be in the luggage in the back of the car, developed into more consistent and louder knocking scraping noise in the rear section of the car. We thoroughly investigated in and under the car several times and bounced up and down on the hitch. In doing so we located the source. We believe it is coming from the cut out in the bumper where the Hayman Reece tow bar protrudes, rubbing on the square tube. When we released the torsion bars the gap had increased . That being the case, it is moving within the gap. Loaded there is a gap of a couple of mm but when the torsion bar is released the gap is 10 mm. I was under the impression that the clearance should remain consistent.
Correct the gap should remain the same when the vehicle is parked on level ground. However the PS shares the same chassis as the Challenger and from my experience there can be a fair amount of chassis twist so this maybe the problem and the cutout in the bumper may need enlargenig. You could try just removing the pinchweld trim from the bumper cut this should improve things or enlarge to bumper cut, it is only plastic and can be trimmed with a sharp Stanley knife and a strong steady hand.

We are driving a 2018 Mitsu bishi Sports and towing a 2 yo Coromal Element 612 with towball weight of 150 and tare weight 2086.
The GTM is 2370 with ATM 2890.
Have you ever had the caravan on a weigh bridge?
Is your ball weight at 150kg measured, this sounds low?

The readings taken of the car wheel arches diimensions were duplicated after leveling and 6 links were used to achieve this.
So if I understand correctly, it is taking 6 chain links of pre tension on the WDH to get the front ride heights back to pre hitching dimension? Is that 6 chain links per spring bar, measured from when all the slack is removed from the chain to the final tension position? This sounds like a lot for a 150kg towball load. What rating are the spring bars? What brand is the WDH.

When the caravan is connected there is a change in height of approx 50mm.
So with the WDH connected and tensioned there is a 50mm decrease in rear ride height? This seems a lot for just a 150kg towball down which will load up the rear coils by about 210-220kgs. I know the rear coils are soft but this sounds a lot]
All bolts were checked and found to be tight.
Assuming these are the towbar bolts? Can you see any signs of movement between the chassis and the towbar mounts? You will have to remove the spare tyre to see this correctly.
We visited some businesses today as we are not prepared to tow until this is sorted but we got a lot of conflicting information. Some suggested airbag and spring combination to assist the WDH from having to be so tensioner up. We are even considering changing to the ugly Mitsubishi regular tow bar.
I can feel some people are seeing a quick sale here. I would be contacting Hayman Reese and get to their local agent to get the towbar attachment checked out. Airbags will not solve your ride height issues, they are a temporary bandaid and the internal rubber cone springs need to be removed.

A trick I used a few years back, whilst touring the Kimberley, and the HD rear coils sagged, was to extend the rear suspension and fill the void between the coils with tennis balls, from memory I managed to jam in about 8 each side. Once the car was back on the ground it gained about 20mm ride height on the rear and these lasted more than 12,000km of touring!

https://www2.pajeroclub.com.au/forum/showthread.php?t=32385

If you can get some tennis balls and get a local mechanic to put the car on a hoist so the suspension is at full droop then this is a 10minute job. It is possible to do this yourself if you are a handy and comfortable working under a car.

I doubt if someone has the correct part number coils in stock so you might have to wait a day or so for new coils. If so King KCRS-23 coils and Peddar 5899 rubber cone replacement combination is the best upgrade if you have no desire for a full suspension change.

But at only 450kms from home, once the towbar attachment has been confirmed safe and the pinchweld is removed and you establish there is 10mm clearance between the bumper cover cut edge and the towbar when the caravan is hitched and the WDH connected then I would be driving home.
Where are you and where is home?

We would welcome your view on this.
Peterb

[Briggsy71]

ANSWERS TO Jacks questions

Thanks Jack for all that info. Much appreciated
In answer to your questions
Yes we did take the van over the weighbridge when we first got it but only for tare weight which was 2150.
The ball weight was tested at home with my Reece ball weight measure. I endeavoured to confirm that today with a borrowed measure and it came in at 155 but the measure was a bit stiff and sticky so I am not 100% confident with that measurement.
Yes it was 6 links either side for final tension to obtain original wheel arch measurement.
The spring bars are Pro Series 600 lb. Standard WDH rated capacity 135-275 kg.
Measurement prior to connecting caravan and towing vehicle - car rear wheel Arch 917mm
Measurement car and van hitched without WDH tension - car rear wheel Arch 876mm
Measurement after final WDH - car rear wheel Arch 917mm
Difference being 41mm for car rear wheel Arch.
Tow bolts have been checked by Reece installer here in Albany and no movement.
Home for us is Perth.
I hope I covered everything Jack.
Thanks again
Peterb

[old Jack]

Thanks Jack for all that info. Much appreciated
In answer to your questions
Yes we did take the van over the weighbridge when we first got it but only for tare weight which was 2150.
The ball weight was tested at home with my Reece ball weight measure. I endeavoured to confirm that today with a borrowed measure and it came in at 155 but the measure was a bit stiff and sticky so I am not 100% confident with that measurement.
Yes it was 6 links either side for final tension to obtain original wheel arch measurement.
The spring bars are Pro Series 600 lb. Standard WDH rated capacity 135-275 kg.
Measurement prior to connecting caravan and towing vehicle - car rear wheel Arch 917mm
Measurement car and van hitched without WDH tension - car rear wheel Arch 876mm
Measurement after final WDH - car rear wheel Arch 917mm
Difference being 41mm for car rear wheel Arch.
Tow bolts have been checked by Reece installer here in Albany and no movement.
Home for us is Perth.
I hope I covered everything Jack.
Thanks again
Peterb

Hi Peter,

If your figures are correct I can see your error, you are putting way too much tension on the WDH, you are trying to get the rear ride height back to the pre hitch level, this is wrong and dangerous. Follow the instructions below;

1. Without the caravan hitched up measure the Front and Rear ride heights fron the centre of the wheel hub to under the wheel arch in a vertical line. So for a example we will use 520mm front and 550mm rear.
2. Now hitch the caravan up without the WDH and remeasure. So you now have 540mm front and 500mm rear. Note the front has gone up and the rear gone down, this is normal.
3. Now slowly and progressively add some tension onto the WDH.
Only add enough tension so the FRONT ride height returns to the pre hitched ride height, so using the sample figures above that will be 520mm.
DO NOT add any more tension than necessary!
4. If you check the rear ride height it would be about 520mm.

Your WDH is now setup correctly.
Please let us know how you go and all the new measurements.

OJ.

[Briggsy71]

Reply for Jack

Hi Jack
Thanks again for your reply and for putting us on the right track. The Hayman Reece instructions I used seem to put too much emphasis on the back wheel measurement instead of directing more attention to the front. I took a lot of time over this, hitched up and on flat road near home, believing I was following the HR instructions to the letter.
You have given us some peace of mind to be able to spend some time in Albany now before heading home. We willow follow your instructions on departure and will definitely let you know what the outcome is.
Thanks again and thanks from my wife too!
Peter.

[Briggsy71]

Hi Peter,

If your figures are correct I can see your error, you are putting way too much tension on the WDH, you are trying to get the rear ride height back to the pre hitch level, this is wrong and dangerous. Follow the instructions below;

1. Without the caravan hitched up measure the Front and Rear ride heights fron the centre of the wheel hub to under the wheel arch in a vertical line. So for a example we will use 520mm front and 550mm rear.
2. Now hitch the caravan up without the WDH and remeasure. So you now have 540mm front and 500mm rear. Note the front has gone up and the rear gone down, this is normal.
3. Now slowly and progressively add some tension onto the WDH.
Only add enough tension so the FRONT ride height returns to the pre hitched ride height, so using the sample figures above that will be 520mm.
DO NOT add any more tension than necessary!
4. If you check the rear ride height it would be about 520mm.

Your WDH is now setup correctly.

Please let us know how you go and all the new measurements.

OJ.

Hi Jack
Just giving you an update regarding the WDH setup using your instructions.
We confirmed the wheel Arch heights - front 877 rear 917.
Our main aim was to achieve the front wheel Arch dimension of 877.
We hitched the trailer onto the car then raised by jockey wheel to achieve a level trailer. We then connected the closest link to the snap up brackets (8 links) and lowered the jockey wheel and rechecked wheel Arch dimensions. Front 877 rear 880.
With these settings the clearance in the rear bumper cutout /tow hitch remained ok.
With these settings we had a noise free comfortable drive home.
Thanks again Jack.

[old Jack]

I am assuming the measurements are from the ground to the underside of the wheel arch.
A more accurate way to measure that removes the tyre compression variable and different wheel diameters is to measure centre hub to underside of the wheel arch.

Sounds like you have solved you problem and happy with the results.

At 37mm rear suspension compression the internal cone springs will just be touching.
If you find you are still pitching too much for your liking then you could try fitting just the Peddars 5899 replacement internal rubber cone springs, these will come it to effect earlier and give assistance to your factory coils only when then need it. These can be fitted without removing the rear coils, all you need to do is have the rear suspension at full droop and it is a simple bolt out, bolt in job that takes about 5 minutes a side.
If you still find the rear suspension too soft then fitting King KCRS-23 will solve this.

Safe travels,

OJ.