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Acty HA4 Suspension Upgrades

Discussion in 'Honda Acty' started by coffeemaker, Aug 20, 2022.

  1. coffeemaker

    coffeemaker Member

    I have a '94 Acty Attack HA4. The front bottoms with an almight whang over some dips in the road. The rear shocks started leaking oil, too, so I set about replacing a bunch of stuff.

    As always, OEM parts are expensive and slooow to get, so this has taken a while and I'm still not finished.

    First, I got replacement shocks for $49 each + shipping from minitruckusa.com, but their web site is down/gone, now. They're good. Tighter then my old, original shocks. The install was easy, my truck actually has little corrosion. And with the shock out, the WirrusWin exhaust was easier to install.

    My biggest problem with the front was metal to metal impact over some bumps. As I suspected, the bumpstops were GONE. Beaten out of it over the years. I ordered replacement struts and OEM bumpstops from Smokey Mtn Imports. The bumpstops came from Japan and swam over themselves. They are a tan, stiff foam that feels like polyurethane. The part number is 51722-SJ6-N01. The price was under $13 each, but you should be able to find suitable replacements in the US a lot sooner. The dimensions are:
    53.66 mm O.D.
    19.5 mm I.D.
    55.6 mm tall.
    I have no idea what the effective spring rate might be, but I've noticed aftermarket bumpstops color coded for stiffness. Tan is the comfort color for a Miata, that is also 54mm tall. Hint!

    The struts were $164 + shippimg and sadly tax, because I'm also in TN. They are also stiffer than my old ones, by a little.

    I measured the OEM spring from the passenger side as it has a taller ride height. My OEM spring was
    260 mm long/tall
    70 mm I.D.
    10.3 mm wire diameter
    33 Newtons/mm (188 lb/in) measured
    12 mm of preload
    the compressed length is 195 mm when bearing the weight of the truck.

    It had about 64 lbs of preload, so it doesn't do crazy when you unbolt the top hat. Whoever suggested using ratchet straps for assemply had a great idea. It works. Tip, hold the nut and use a ratchet drive hex key on your inpact wrench to remove the top nut. Just to reverse directions on the impact because you're screwing the shaft into the nut to get it loose. I torqued the new nut to 30 ft-lbs with the same technique.

    I have ordered new springs from Summit Racing. I went with 250 mm x 70 mm I.D. x 50N/mm spring. That's a 50% increase in rate, but 10 mm shorter. $76 each and shipping included.


    It will have about 2 mm of preload and best yet, will only raise the truck a calculated 17 mm in the front, making it about level. It should be super easy to install. If you really want to see my calcs, send me a PM.

    I posted all this because there is a dearth of info about the Acty and I found at least four $300 spring kits, all with different rates, plus several other folks saying a 2.5" (63.5 mm I.D.) spring fit perfectly. It couldn't. Based on other cars I've worked on and motorcycles, don't bother with less than a 25% change in spring rate, unless you are fine tuning for some sort of competition.
    Last edited: Sep 5, 2022
    Carlos A Iglesias and shogun like this.
  2. coffeemaker

    coffeemaker Member

    Finished and satisfied. I can now run my 14" wheels with no rubbing and no metallic WHAMS.

    The biggest trick was the bumpstops, but the springs control motion well enough. The ride height ended up about 3/8" higher. Oddly, the right front is still about 1/2" lower. It still is slightly higher in the back.

    This is the Spring I chose.

    Here you can see it fits the bottom spring perch well.

    However, it is a touch too large in O.D. for the upper perch, due to the larger wire dimeter of the stiffer spring. You might try a 65mm I.D. spring, but the 250 length is good.

    Acty Wheels.jpg
    Final results.
    Last edited: Sep 5, 2022
    shogun likes this.

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