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Suspension and other mods for near new Final Edition

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  • #16
    Hi Bam Bam,

    My comments in blue font within your post below.

    OJ.

    Originally posted by bambam351 View Post

    Thanks for the detailed reply OJ.

    I currently run 8yo Lovells struts, shocks and springs(strut now leaking after 130K, 290 on the clock now). I can't find the paperwork but pretty sure it's:

    Frt - CFR-90EHD spring. Pretty happy with how the front end goes - will probably keep those springs.
    I do not have any specifications on file for Lovells front coils. only Factory, Old Man Emu and King.

    Rr - CRR-91 with airbags to 30psi. Thinking of upgrading to a more suitable spring. When loaded and towing it sits well with 30psi in the bags but without the bags it noticeably sags and upsets the cars balance and steering. I would prefer to have less reliance on the bags but don't want it to be an absolute pig when not fully loaded (I know, not asking for much...). There are plenty of posts to pour through regarding the springs.
    The CRR-91 is a very lightweight aftermarket coil, free length of 355mm and a linear spring rate of 13.2kg per mm, factory coils are 350mm free length and a linear spring rate of 11,6kg/mm. next step up is a Lovell CRR-91HD with free length of 345mm and a linear spring rate of 15.5kg/mm, I would call these a medium duty coil and not suitable for rear axle loads that vary greatly or are more than a few 100kgs. If your rear axle load varies then progressive rate coils are the best option. If you can post your unloaded, loaded and loaded & hitched, axle weights and rude heights then it takes a lot of the guess work out of coil selection.

    Running all the usual stuff - steel bullbar, towbar, Rhino platform rack, rear drawer setup, fridge, battery, compressor, recovery gear, TREADS, spares, tools etc.
    It is amazing how all the usual stuff adds up to a lot of weight!

    The Camprite is 1700kg with about 150kg ball weight.
    Have you weighed it when fully loaded, I suspect it may be more.

    Fully loaded the Paj is at max 2760 kg GVM and either through good management or good luck the fr / rr axle loads check out give or take 10-20kg
    Camprite camper trailers are a great design and built family camper, I recently saw a fibreglass copy of the Camprite advertised but cannot recall the name.

    I really want to say that I spend 25% of the time off road exploring this great state of WA but I would be kidding myself...
    But when we do we like to get amongst it and heavily corrugated roads and slow rough tracks are usually involved.
    The current setup is great on the blacktop and around town but I'm really hoping to improve the dash rattling ride on corrugations.
    This could be difficult given the age and kms already travelled, softer compression struts and shockers will assist as will lower tyre pressures.
    Airbags are meant to add progressive spring rate by expanding between the coil winds and restricting the coil winds compression, when this happens you change the springs rates considerably especially at high inflation pressures,

    Off road articulation seems to be pretty good as is, hopefully a heavier rear spring doesn't reduce that too much.
    The downward suspension travel is not effected by and increase in spring rate but the upwards travel is especially if the spring rate is too high you can lose some tuck, but you do gain ground clearance, so once again it is a compromise.

    For an extra $100 the IMR's are great value for what on paper looks to be a very well built top end style shock.
    Those RMM failures have me second guessing the reliability bit though...
    My same thoughts when I was tossing up between MT/IMS and OzTec. As I said previously the MT's on my PB Challenger are great off road and on rough roads but they do allow more body roll on the bitumen but it is controlled and predictable.
    2011 PB Base White Auto, Smartbar, Cooper STMaxx LT235/85R-16,TPMS, HR TB, 3 x Bushskinz, front +40mm Dobinson , rear +50mm EHDVR Lovells, Dobinson MT struts and shockers, Peddars 5899 cone springs, Windcheater rack, GME UHF, Custom alloy drawer system inc. 30lt Engel & 2 x 30 AH LiFePo batteries + elec controls, Tailgate hi-lift/long struts, Phillips +100 LB & HB, Lightforce 20" single row driving beam LED lightbar, Scanguage II.
    MM4x4 Auto Mate, Serial No 1 .

    Comment


    • #17
      Originally posted by old Jack View Post
      Hi Bam Bam,

      My comments in blue font within your post below.

      OJ.


      Thanks again OJ for the pearls of wisdom.

      It's looking like a shock replacement is going to turn into spring upgrade as well. May as well spend the bit extra and spring it right now than blame some blown / leaking shocks because of inadequate spring rates and load carrying capacity.

      I will do the weight and height measurements prior to our trip away at the end of next week which will be a typical fully loaded setup. Any advice on spring choice would be much appreciated.
      We do love the Camprite - tough as nails with a build quality next to none. It actually weighs in at 1700-1750kg with 160l of water in the tanks and depending on bikes / kayaks etc on the racks.

      As for the Dobo / OzTec debate I have have been Googling until my eyes bled last night at work.

      OzTec - Very hard to find any negative press, forums, reviews or problems with their products. It's also hard to find any actual information, specifications or even photos as the website is bloody awful and pretty much useless. Very hard to compare specs if there are none....

      Dobo IMS - it appears much of the negative news was from 2016-2019ish and mostly with the MRR range (same shocks without the ext bits). From what I can tell the actual shock was ok but all the external bits and connections were the problem. Apart from some flogged out bottom rr bushes (possibly now corrected) and some busted top strut mounts (possibly a valving/tuning problem caused this) they seem solid. Also read that the IMS are now *possibly* being assembled in China and that only their premium off-road race stuff is now Aussie made.

      All food for thought - or am I overthinking it???



      Comment


      • #18
        Hi OldJack

        Thanks for the comments. Much appreciated. Needs a bit of explanation from me. Should probably have been clearer about vehicle loading. My Comments below yours in red.



        Went to the weighbridge today and made the weight and EBH measurements. Attached table summarises the three cases:
        1. Pajero and van, unhitched
        2. Hitched no WDH connected
        3. Hitched with WDH connected

        Image 14-1-22 at 02.04.jpg

        The minimum legal rear ride height is 488mm so even with the WDH connected the rear ride height is lower than this.
        Shows how soft the original suspension is. Of course never my intention to tow van without modified suspension.


        (numbers don't add up, probably due to weighbridge accuracy and rounding to10kg. Paj and van unhitched weighed 20kg more than hitched somehow)
        I believe most certified weighbridges only have 20kg accuracy, so on a 20 ton weighbridge 20kg is 1/10th of 1%.

        Interesting to see the 160kg drawbar weight add 280kg to the rear and take 140kg off the front with the WDH not connected, then the WDH shifted 160 from the front to the rear. Front ending up with close to original load when caravan not connected.
        How did you determine the towball down load? Has this scale been checked for accuracy? If you towball centre is inline with the rear most face of the spare wheel cover then a 280kg extra rear axle load calculates back to a 180kg towball down load. Your current WDH setup is applying a little too much tension as you should aim to have the front ride height return to the pre-hitched height. This is why there need to be positive rake angle of 30mm to 45mm between front and rear ride heights.
        Public weighbridge at road transport company, so probably reliable. Good set up, 3 sections to the weighbridge so you could be on more than one set of scales at a time. Weighbridge measured the towball load. Total caravan weight sitting on wheels and jockey wheel minus just caravan axle load. Should be fairly accurate as they were both measurements well into the load range. The 160kg was close to the figure I got using a small cylinder type towball measuring device.
        Thought that might be the case with the hitch and will make some change to lengthen the chains. I guess that's an empirical thing, increase the length a bit and see what happens, or is there some more science to it?


        I believe these numbers are similar to those of PaulMcg some time back. His usage requirements are similar to mine so I'm thinking his solution of front KCFR-34H and rear KCRR-35 with Dobinson IMS front and rear may suit me.
        I seem to recall that Paul McG front ride heights were too high when his camper trailer was hitched up so we went down a spring length but kept the same spring rate, the exact part numbers will be in a post somewhere. I also recall that he only has a nudge bar and maybe some aftermarket underbody plates fitted, if my memory is correct..
        Didn't see that bit in PaulMcG's posts. Will go back and have another look. I thought he ended up with the KCFR-34H/KCRR-35 combo so I'm hoping he may post some comment.

        My uncertainties are twofold.
        First, will the KCFR-34H be stiff enough to cope with Smartbar, winch with Dyneema rope and bash plates yet to fitted, without losing too much of the lift. Suspension on previous Paj was OME with front coil of 14.11kg/mm so is the 34-H at 11.9 too light? Going to KCFR-34HD takes it to 13.6 kg/mm which is getting close to the OME coils which were too harsh, but it's a bit less and with the better Dobinson shocks maybe the ride would be better.
        The front ride height is determined by a combination of the spring rate, coil free length and the pre-load caused by the lower coil seta height. The advantage of the IMS struts is that there is some adjustment available in the lower coil seat, but this must be done with the strut removed and the coil compressed.
        The factory front coils have a free length of 315mm and a spring rate of 10.36kg/mm and I consider this spring rate too light. King KCFR-34H have a free length of 335mm and a spring rate of 11.98kg/mm and the 34HD has a free height of only 320mm and spring rate of 13.6kg/mm. I would wait until the Smartbar and winch are fitted an then re weigh both axles because there is a leverage factor to consider that will transfer weight off the rear axle and on to the front, in principle the same as the multiplying effect of towball downloads have on the rear axle.
        I should have been clearer. Conditions when weighing were:
        • full tank of fuel
        • no-one in the vehicle
        • 3rd seat removed, but compressor, recovery gear and some tools in place. Approx same weight as seat.
        • Tool box in rear close to rear door - say 15kg
        • Smartbar and winch are already installed so weights included in these figures,
        • Bushskinz not yet, so either 15 or 30kg to add depending on whether I go alloy or steel.
        When we travel while towing there can be another approx 100-150kg in the rear of the car. Second row seats removed so weight as far forward as possible. If camping rather than caravan then load in rear/on roof higher, but this is not frequent so not such an important design case, and perhaps it could be handled by higher pressure in the airbags.

        Second question relates to rear. OME coils at 12.5-16kg/mm worked well when towing and used in conjunction with WDH and airbags where necessary, while not being too harsh unladen. The KCRR-35 is similar at 11.7-17.8 kg/mm so I assume would be suitable, but most selection tables on supplier websites would suggest 35HD which is significantly stiffer at 14 - 22 kg/mm.
        Factory rear coils have a free length of 350mm and a linear spring rate of 11,6kg/mm which is way too short and soft for your loads.
        The KCRR-35HD has a free length of 335/345mm and progressive spring rates of 14.3 to 22.3 kg/mm. I have fitted these to a Gen 4 NW and done actual load test, at 1250kg rear axle load the EBH was 568mm so 35mm above factory specification and at 1430kg rear axle load the rear EBH was 558mm. There will be a variance in coil free lengths and the compression on the upper and lower coil insulators which will have a multiplying effect on the ride height for any given load. So given your rear axle loads this coil would work without airbags bur ride significantly firmer than the factory coils..
        Either the KCRR-35 with a free length of 345/355mm and progressive spring rates of 11.8 to17.8kg/mm + airbags or the KCRR-35C with a a free length of 370/380mm and progressive spring rates of 9.6 to 15.3kg/mm + airbags would also do the job and provide a softer more comfortable ride when empty. The KCRR-35C will ride softer than the KCRR-35.


        Would be very grateful for some comment OJ regarding this proposal and likely resulting performance/ride heights. This vehicle is our only one and is the town car as well as bush truck, so I'm hoping to get the balance of suburban comfort with a load capacity when towing a relatively small caravan assisted by WDH and airbags.

        Also any users with this setup or similar how you feel about it after a period of use.

        Comment


        • #19





          I believe these numbers are similar to those of PaulMcg some time back. His usage requirements are similar to mine so I'm thinking his solution of front KCFR-34H and rear KCRR-35 with Dobinson IMS front and rear may suit me.
          I seem to recall that Paul McG front ride heights were too high when his camper trailer was hitched up so we went down a spring length but kept the same spring rate, the exact part numbers will be in a post somewhere. I also recall that he only has a nudge bar and maybe some aftermarket underbody plates fitted, if my memory is correct..
          Didn't see that bit in PaulMcG's posts. Will go back and have another look. I thought he ended up with the KCFR-34H/KCRR-35 combo so I'm hoping he may post some comment.


          You are both correct to some degree. I did go with the KCRR-35 rear/ KCFR-34H front combination, and I did end up with front ride heights a bit higher than I was trying to achieve. (560rear/545front). I did talk at length with OJ regarding this, and did discuss either trying the shorter KCFR-34, or trying to get some adjustment by swapping the slightly different lengthed KCFR-34H's from left to right, and readjusting the spring seat heights on the IMS shocks, which should have theoretically lowered my front heights slightly.

          Eventually, I decided to run with it as it was, and monitor. I was ending up a bit higher at the front than optimal with the van hooked up, but as I always use WDH's, I could return it to an acceptable height. Now, over the course of approximately 35,000kms, with a fair amount of towing, I am seeing heights of around 555 rear and 535-540 front.

          I'm overall happy with the end result. I still find the ride quality a little harsh over chopped up country B roads or suburban back streets when using as a passenger vehicle, but the package works well for towing (we do a fair bit of towing over back roads, not just highways) and for any off road driving we do, which is usually nothing more than fire trails or dirt roads.

          I did try lowering tyre pressures, (to 36 PSI all round) as OJ suggests regularly. While it did improve ride quality marginally, it resulted in noticeable and measurable uneven tyre wear in the classic "under inflated" pattern after approximately 5000 kms, so I reverted to the tyre supplier's recommended 40 PSI all round, and the uneven wear pattern has been remedied. (I run 44PSI rear/38PSI front when towing.)
          NX 2016 GLS (non-DPF); MMA towbar, nudge bar; Boo's intercooler, sump, transmission Bash Plates 3mm; Donaldson secondary FF; Provent Catch Can; SPV mod; Stedi ST4K 28" lightbar; Falken Wildpeak AT3W; MM4x4 Auto Mate; Kings raised coils/ Dobinsons IMS struts & shocks.

          Comment


          • #20
            Hi Paul

            Thanks very much for both of your responses. It is much appreciated and confirms some of my understandings.

            I've gone with King coils, OzTec shocks plus Airbag Man airbags. Coils are 34H front and 35HC rear. They're being fitted next week, along with a set of Maxxis Razr AT811s onto my steelies.

            I'm fairly confident that the front will be ok based on your experience and that of others like Jaffles and Two Emms. It will certainly give a more comfortable ride than the OME setup I had on my NT. That had front springs of 14.11 kg/mm and were too harsh in the rough. The rears, at 9.6-15.3 kg/mm, will be similar to my last set that worked quite well at 12.5-16 kg/mm, but I'm hoping they will also be a little more supple around town.

            Like you, I am a big believer in using the WDH to help. I think they improve the attitude of the vehicle, weight distribution and feel, and reduce fore and aft pitching. They also allow more forgiving coils to be used that better suit the unladen vehicle when used in town. When we are just towing with not much load in the vehicle I don't have much air in the airbags, but if we are carrying a lot of gear in the car as well as the van then I have more air in the bags. Seems to work well. Have to confess though that it is rare for me to remove the WDH when off-road. Only in fairly extreme circumstances that require a lot of articulation. I changed to a McHitch a while back and he supplies rollers for the end of the chains supporting the WDH bars. I think that makes it a bit more forgiving as the chain/bar connection is not "fixed". I'm a big fan of his hitch, works well and makes it very easy.

            Thanks again for your help, and I'll post some comments and numbers after the lift.

            JK

            Comment


            • #21
              I tow a camper with a ball weight of just over 100 kgs but may be looking to upgrade and I can see that weight ending up more like your 170 kgs.

              I have KC-RR35HC s in the rear so will be very very interested in your results

              2016 NX GLS Factory alloy bar, Provent 200 catch can, Boos bash plates (full set), Stedi light bar, 40 litre Waeco, Titan fridge slide, Kings springs, Dunlop ATG3s, Auto-mate, Ultragauge, Uniden 8080s, more to come...

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