Rear dampeners (shock absorbers)

[Ent]

Looking at feed back and options for rear dampeners for a PC Challenger running heavy duty GVM +150 kg springs. The front Drummond Motor Sport struts work a treat but rather disappointed with the Bilsteins. They were marginal with mid rate rear springs but rather struggle controlling the heavier springs. One option is revalving them. Another is different dampeners.

Lot of hype on dampeners but rather hard to get sensible information. Dampeners are one thing lot of people on the forum have had issues with on long corrugated road runs. Not a fan of cynical marketing Mexican or Asian dampeners with trendy names, and wish to avoid foam dampeners as once they over heat they are "dead".

Koni's are adjustable but are not approved for use by Koni on the Challenger. Part of the reason is lack of clearance with the big bore. Koni's would likely need to be correctly valved and setup for the much higher spring rate I am using rather than the one setting suits all.

Sadly Drummond Motor Sport do not make a suitable rear dampeners. The ones I trailed were too long and were destroyed when acted as impromptu bump stops. But boy did they give a great sense of control.

So anyone had luck with dampeners using extra heavy duty springs?

[nj swb]

I'm in the same spot - happy with the front, but rear is sadly under-damped.

I'm not convinced that a conventional shock will work for us - it may be OK on-road, but I suspect that the sheer amount of kinetic energy that we expect them to control is too much. If valving can provide adequate control I suspect the shock won't be able to dissipate enough heat to sustain the right level of performance. So I believe remote reservoir construction is required for heat dissipation.

I'm currently trying to have my MRRs re-built (hose wore through & they don't work at all well without oil). Having seen them apart, the valving is adjustable if you can obtain the correct size shims - but I don't know if Dobinson will sell shims, or if they'd insist on doing the rebuild. Shims are very close in dimensions to Fox shims, but not close enough (as I understand it).

Dobinson list a MRR for PB-PC Challenger, but I don't know what the valving will be like.

King shock absorbers don't list a fitment for anything Mitsubishi, but they do have "build to order" specs for a Gen 3 & 4 Pajero (or Montero, in US speak). I'm not sure they'd have anything for a PB/PC Challenger.

I did notice they have a number of listings for a range of other brands of 4wd. If you can identify a fitment for another vehicle that will bolt in (right ends / lengths), it may be possible to have it re-valved to suit your application.

[Nab]

Can you extend your rear bumpstops so you can use the Drummond shocks?

[Ent]

I agree it will be a long research project to find alternatives. Sometime back I spoke to a dampener expert that was a Koni rebuilder. He when testing dampeners for a 4x4 racing team running in an unmodified class found gas dampeners built up a lot of heat until seals melted. A well designed oil dampener was the choice. He got Koni to release a truck dampener in lengths suitable for the Toyota 80 series as they on a trip to Australia finally understood thousand kilometres of corrugated destroyed standard European dampeners. He then spent a long time sorting out the valving. Sadly, the Koni 76 series is too big in the body to fit the Challenger.

Many people are running heavy duty rear springs so it makes no sense to valve for the standard rear spring as most chuck these away.

A remote reservoir dampener is the solution for the Challenger. Getting them is the battles. Not a fan of hoses as they fail. I like the Drummond integrated design.

Once again the battle is one to find or convince a company that the Challenger is a serious 4x4. I have written to King but not expecting much.

The ideal dampening rate is one where the vehicle just avoids losing height as it travels over bumps. If you get a greater rebound height than standard height then the dampener is not up to the job.

As mentioned all a dampener does is convert kenetic energy into heat. That means larger the fluid reserve greater the ability to cool.

Foam is useless in these conditions as once the dampener overheats it is dead. Something like a Bilstein design the gas heats up compressing the oil so it resists fading until the pressure forces past the seals or the seals melt.

The Koni expert maintains looking after the oil to stop is frothing is the secret so valve design is critical along with the amount of oil and the ability to get rid of the heat.

[Toddyh]

Recommend speaking to Ultimate Suspension. I have very heavy rear springs and have had their shocks for a number of years now. They have done the job over thousands of kms of corrugated roads and tracks. I've done 135,000 in less than 4 years and these have been on for the majority of them.

[littleriver]

Oztec shocks

http://www.oztecsuspension.com.au/

Review;

https://www.4x4australia.com.au/gear/suspension/1605/oztec-outback-shocks-product-test

Just set our car up with them and kings springs ... couldn't be happier
575mm front
590mm rear
NB no bullbar

.....

[Ent]

Email sent to King Suspension (believed not related to Kings Springs) no response

I ruled out Drummond rear as they are a very long dampener and playing with changing bumpstops on the Challenger is not straight forward as you have rubber cones and bumpstops to worry about and limited ability to lift the rear end. Also, they foul on the brakelines. Also happy with DooSo as he is now, as has good rear height and suspension travel. Would not go any higher so all I could do is sacrifice suspension travel.

Koni do the 30 and 82 series but finding it dam hard to work out what is the difference. They have some rebound adjustment. They can be revalved as well. Rather kicking myself I did not first go with them.

OME are part of ARB and frankly I would like to avoid that company. Better to buy Monroes and replace frequently. Besides their remote reservoir as expected from ARB are not available for the Challenger (hint it is not a Toyota).

Rancho 5000x are an option. Much debate on them versus Bilsteins but they are not adjustable. They do claim to have larger oil capacity. Might be an option.

Bilsteins B46 which I have appear to develop leaks and rather underperform. Valving is wrong for heavy duty springs. Could get mine revalved but still have the issue on their ability to handle heat buildup.

So far nothing grabbing my fancy. The Koni 90 series is not available as likely too big in the bore to fit the Challenger. They would be great choice otherwise.

Might ring King direct rather than email again. Gut feeling is they probably do not do the Challenger.

As usual hard work to find better quality bits for a Challenger. I know through experience dig long and hard enough and eventually something great can be found.

Will check out littleriver's lead. Only thing might find they are merely a rebranded Monroe, not that is an issue if valved correctly for heavy duty springs.

[littleriver]

Will check out littleriver's lead. Only thing might find they are merely a rebranded Monroe, not that is an issue if valved correctly for heavy duty springs.

Read some where they are very similar to a Tjm shock but slighty modified for the better hense the limited life time warranty

....

[Quinno]

KYB Skorched. I have them with King Spring (KCRR-23) on the back. A bit longer extended length would have been good. It's 517mm extended whereas others are around the 525mm to 535mm.

[Ent]

Well Climax was a bust with nothing suitable being their response. Curious as they sell extra heavy duty rear springs which would likely have similar spring rate. Maybe a case once the dampeners wear control is lost over the springs quicker than otherwise, but meantime you are out the door a year or two on.

Rancho believe that they have similar valving to the Bilsteins with no custom valving option.

Kings Springs suggest Koni or Tough Dog as an option as they use them on heavily loaded military vehicles with good results. Trouble is the 88/90 series is not available due to the Challengers limitation on the maximum diameter. Might be 82 Konis set to then end scale of their rebound rate, and then if not up to scratch then custom valving?

Might check out re-valving the Bilsteins depending how they fared. The trouble is you need a skilled person to get this right and I have my doubts over the actually quality of the Bilsteins on hundreds of kilometres of corrugated roads.

As expected not as straightforward as hoped. Also, getting the usual disjoint between marketing hype (our product is brilliant off-road) and actual willingness for suspension places to back the product when they encounter a vehicle that is used as intended rather than setup as a city posser. Basically, the fable of the Emperor's new clothes springs to mind.

[littleriver]

Did you ring for an enquiry on Oztec Suspension ... they are quite thick and just clear ...

...

[nj swb]

My NT came with Tough Dogs. I'm not sure how old they were, but the entire vehicle only had 20k km on the clock, and the shocks would fade just driving on the highway. I wouldn't touch them again.

[Ent]

I will give them a ring.

It appears that some of the bigger bore dampeners have clearance issues on the Challenger. Koni Netherlands has made it clear that while their dampeners might fit they should not be used on the rear of the Challenger as the required clearance is not there. Interesting, as they are still listed on many websites as an option. I respect Koni for their upfront honesty but it does rule out an excellent dampener.

Nothing wrong with the front as even the Koni 88 series can fit, but given the price I would go for Drummond Motor Sport front as then you get adjustable spring heights as well. This was a real advantage as when I added a bullbar and a winch it was just a matter of cranking up the front end. Also, you can level the vehicle and play with the front height that best suits. It is hard to convey the absolute quality of construction of the DMS. You have a serious setup at a fair price given the quality.

[twisted32]

Could be worth contacting Ultimate Suspension, as they valve their shocks to suit the application (and spring rate), and may be able to assist.

[Ent]

Rang Oztech Suspension. Impressed with their approach. They believe that the Bilstein correctly valved would be the way to go. They mentioned that the B46 series has the best progressive valve design on the market so worth developing that. Their dampeners are designed to ride softer so probably not as suitable as the Bilsteins as they are designed for firmer control. They noted that no Konis would fit the rear so ruled them out.

So looks like hunting for a dampener tuning place. Oztech, as did another place, warned me it is a job for someone on top of their game, else could be wasting my money.