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Thread: D2 p38 front airspring conversion

  1. #1
    Join Date
    Apr 2017
    Location
    Adelaide
    Posts
    12

    D2 p38 front airspring conversion

    I have just finished converting my D2 front axle to air springs. The only problem is the ride is quite rough over man holes as I suspect with the softer spring rate it is bottoming out on the bump stops with the impact. The ride heights between D2 and the p38a are very similar, with exception of bump stop clearance.

    D2 ride height is 500mm and 44mm bump clearance.

    P38a ride height is 495mm and 100mm bump clearance.

    The p38a has and extra 56mm of travel before it hits the bump stops. Giving the D2 a 56mm lift would give the spring the 100mm of compression space back. But that is assuming that the bump stops on both vehicles are the same distance apart in relation to the upper spring perch.

    Does anyone know, or could measure for me, the height of the airspring between the upper and lower spring perches? I.e the airspring height at nominal ride height of a p38a.

    Thanks

    IMAG2521.jpg

  2. #2
    Join Date
    Dec 2016
    Location
    Woolgolga
    Posts
    72
    Nice work can't help with your question but I like this..

  3. #3
    Join Date
    Sep 2010
    Location
    Dandenong Ranges.
    Posts
    5,817
    Can't help, but I am wondering, what pressure you are running in the bags? How is that controlled?

    Edit: Also, how is the ride height controlled? Does it work in conjunction with the SLS, or is it independent? Hitting the bump stops on a man hole seems a little extreme.

    Love this, BTW. I want to do something similar to a Deefer, but there are kits for that.
    [SIGPIC][SIGPIC]



    Real stupidity beats artificial intelligence every time. Sir Terry Pratchett

    2000 D2 TD5 Auto: Tins
    1994 D1 300TDi Manual: Dave
    1980 SIII Petrol Tray: Doris

  4. #4
    Join Date
    Dec 2016
    Location
    Woolgolga
    Posts
    72
    How did you mount the shocks?

  5. #5
    Join Date
    Apr 2017
    Location
    Adelaide
    Posts
    12
    Ill start from the beginning....

    It is an original SLS, non-ACE TD5 manual car, that the previous owner had changed to coil. I bought the car and a few years later the springs started to sag. The car is used for towing trailers and moving stuff, so i didn't want a lift and ended up going for standard height kings springs and efs shocks. Lets just say i wont recommend that combination unless you like lower back pain and forklift like suspension on Adelaide roads. After a year i decided that i could not live with it anymore and needed a softer ride. The car has a trade roof rack and the load can vary in weight between empty and completely full, so air springs suited my needs. Without too much modification there are only 3 airsprings that will suit the weight and height for the vehicle, 2 Firestone (9327 and 9310) and the p38a front springs. The 2 Firestone springs are essentially identical except one has a top plate with studs and the other with blind thread, both are horribly expensive at approx $400 each and had a 10 week lead time. I excluded Firestone 5422 as there is more work involved in moving the larger diameter airspring away from rubbing on the chassis rail.

    I did see a kit from airbag man in QLD selling a kit to suit a defender OA6015 ($1500+ gst). I work with air suspension every day and decided i could make my own kit.

    BA2157s -2" twin shock kit to suit a D1 $238
    REB101740 p38a front airsprings $200
    STC2830 RRC front shocks (air spring equipped) $50
    4x 150mm 6mm steel plates. $35
    And a few assorted countersunk bolts.

    I made up some adapter plates and adapted the twin shock kit. Ill do a proper write up when i pull it apart and put the johnny jointed radius arms in.

    ok, questions....

    The air pressures at 500mm is about 75psi, the sls is still disabled and the front and rear bags are fixed pressures on independent schrader valves. Once i get the height and ride sorted i will be going to a air ride height-adjust computer controlled system with on-board compressor. Once the air ride system goes in, the next mod will be custom valved fox shocks for suit air spring characteristics. Standard shocks are not suited for air springs.
    If the airspring is not at the correct operating height and air volume, the spring rate will much lover and cause it to bottom out. Airsprings are a progressive spring rate, the more compressed they are, the higher the pressure and thus higher spring rate. So if it is too low the car will bottom out easier.
    IMAG2526.jpg
    I modified the lower mounts from the twin shock kit and are bolted and welded to the axle.

    IMAG2527.jpg

  6. #6
    Join Date
    Apr 2017
    Location
    Adelaide
    Posts
    12
    I had a really nice explanation typed out, but it has deleted itself.

    Short answer, SLS had previously been disabled and front and rear pressure/height is controlled manualy with schrader valves. 75psi front and about 70psi rear. I believe that the air springs are sitting lower on the D2 vs the p38a, and are running at a much lower spring rate, as they are not at the correct operating height. Once i get the ride height and comfort sorted, i will be installing a air ride height based SLS system. I looked at the kit for the Defender, but it was $1500 and i work on air suspension for a living, so i made my own. Bearmach -2" twin shock kit, 2x p38a front air springs, rrc eas front shocks and 4x 150mm x 6mm mild plate. Cost about $550 and some of my time.

    The shocks are mounted using a twin shock kit for defender/D1. If going down this track, make sure to get the -2" kit otherwise it wont fit under the wheel arches. Ill do a better write up on it when i install my adjustable radius arms.

    IMAG2526.jpg

  7. #7
    Join Date
    Dec 2016
    Location
    Woolgolga
    Posts
    72
    Nice work.
    Maybe you could fit the EAS system from a p38 or find a cluey computer head who could build an arduino controller to do the job.

  8. #8
    Join Date
    Apr 2017
    Location
    Adelaide
    Posts
    12
    True, but the air ride system is aus compliant and has had heaps of r & d. The p38 eas is too complicated.

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