Front and Rear "shock" replacement

4 Paw Drive Jun 12, 2018

  1. 4 Paw Drive

    4 Paw Drive New Member I am in scotland

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    Hi,

    I'm looking to put new "shocks" for the AHC suspension on my 2001, 100 HDJ . I am at this moment going down the road of putting Mr T ones back in so the AHC still works with confort/ sport setting, but may reconsider following others thoughts.

    I have been through the Max Ellery manual and this has conflicting info for front and rear removal and also trawled the Mud forum but still have concerns.

    The Ellery advice for the front removal is, to drop the ride height whilst the wheels are on the ground to low and switch off the engine. Then jack up and remove the 2 nuts holding the AHC linkage to the top of the shock then remove the top 22mm "shock" nut and then bottom nut, remove the old one put in the new.

    Question is, by dropping the vehicle to the low setting, will this release the pressure in the system or does it still require bleeding at the back of the spheres?

    Also on removal of the rear shocks, there is no mention of dropping the suspension to release the pressure which doesn't seem right?

    Any guidance would be appreciated.

    Thanks

    4 Paw Drive
     
  2. uHu

    uHu Well-Known Member I am in sri_lanka

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    Probably, the question is flawed and you don't need to consider it.
    There wouldn't be any reason to change the shocks unless they are leaking (in which case there wouldn't any pressure left) or they are rusted so badly that they wont last another month. Which reason is yours?
    And I suppose that with "shock", you mean the object that looks like a shock absorber, but actually is just a hydraulic ram for the AHC suspension system.

    But, to your actual Qs:
    First, forget about Max Ellery or Haynes for this car. They are so full of errors and inaccuracies that you are in great risk of destroying something. The Factory Service Manual is very good though.

    The pipes in the ahc system are under a very high pressure, and should always be bled off before undoing anything. In theory the pressure to the shocks is zero after letting it down to Low, but I would still open the bleeder before undoing any pipe, hose or sphere. (Although, after dropping to Low and then jacking up on the frame, would give a vacuum in the pipe actually). And it would be the same for front and rear, and also separate for front and rear btw.
    One thing that is good to know on beforehand, is that the tops of the rear shocks are very hard to get to. Some people actually drill a hole in the floor just above the shock to put a 22 mm socket through.

    But, back to the big question. Why would you want to change the shocks?
     
    GeekOKent likes this.
  3. Shayne

    Shayne Well-Known Member Guru

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    Its not something i know anything about but i believe some rather than fix the AHC prefer to remove it and fit traditional suspension instead .
     
  4. 4 Paw Drive

    4 Paw Drive New Member I am in scotland

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    Shane, uHu,

    The rest of the systems in pretty good nick so unless something is really untoward i plan to keep the AHC system, will know better when i start stripping bits off.

    uhu, you've pretty much nailed it, front drivers has had a leak, (basically misting for the last 5 years, it keeps coming up on its MOT as an advisory) usually wipe it clean with a cloth before she goes in and thats enough to get the pass, and keep topping up the AHC reservior.
    The rear passenger is about rusted right through to so although everything else is working fine just wanted to sort, once and for all.

    I'll bleed the system to release pressure and see how getting the rear one out goes. Not adversed to cutting the floor but will give the working from outside a shot first.

    Thanks for your replies.

    4 Paw Drive
     
  5. uHu

    uHu Well-Known Member I am in sri_lanka

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    That sounds good then. I do like the system as well, and have stacked up on spares to keep it going.
    Just remember to remove the spare wheel before attempting the rears. I have seen that some prefer to use a 22 mm flex-head rachet spanner for the top nut. It is also possible to lift the body from the frame an inch or so for better access. Rusted body-bolts can get in the way for that tho'.
     
  6. 4 Paw Drive

    4 Paw Drive New Member I am in scotland

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    Okay a wee update, got both front and back "shocks" off and ordered new ones should be coming later this week.
    Now looking for any advice in the installation side of things.

    Does anyone have any dos and don'ts when putting it back together to avoid air in the system or any potential problems with anything else , electrics etc, or is it just the case of fill the new "shocks" up and fit it all back together? and everything should be fine?

    Any advice would be truly welcome.

    Thanks

    4 Paw Drive
     
  7. uHu

    uHu Well-Known Member I am in sri_lanka

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    Lucky you - got the rears off. A report on method, time and problems would be welcome.
    Filling up the shocks before fitting makes the bleeding a bit faster. Otherwise it's just "put them on and bleed well". The only problem I've heard about is getting air into the pump, which is supposed to be self bleeding, but not always 100%. :)
     
  8. frank rabbets

    frank rabbets Well-Known Member

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    My pump would not bleed so I took outlet pipe off it and turned ign on. Fluid everywhere but it got the pump going.
     
  9. 4 Paw Drive

    4 Paw Drive New Member I am in scotland

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    Front extraction;
    Liberal use of PB B'laster on the 12mm bolts a six sided 3/8 socket and patients, a little off, a little on etc and they came off not to bad. Pried the hydraulic top piece of with an old chisel and gentle easing.
    Now 22mm top nut, not enough room to get a 1/2 socket in as the wrench hits of the wing body work, didn't have drop head ring spanner so cut 10mm of the 1/2 22mm socket and welded to a bit of 40mm flat bar, perfect, now "shock" spinning! tried various pipe grips but nothing could grip it.
    Spoke to fitter at work, got a lend of :
    https://www.drapertools.com/news/draper-expert-induction-heating-tool-kit-delivers-superior-results/
    mindful of reading somewhere that hydraulic fluid is flammable, removed bottom nut from"shock" and squeezed out as much fluid as possible, good soak with garden hose and good to go. Put induction heater on and 12 seconds later shock off. Great tool, could do some damage with it though!

    Rear extraction;
    Played with the 12mm bolts for a while, number of times i rattled my head of the spare wheel locating bar i dread to think!, got three off but the passenger one nearest the front wasn't for giving it up easy.
    In the end went for the easier method, and cut a hole in the floor plan 50mm, in from above and a joggle bar on the offending bolt and it came easily. 22mm on the impact gun made light work of the larger nuts not even requiring the "shocks" held.

    Am i right in thinking there two bleed nipples to each actuator, a total of eight points to bleed?

    4 Paw Drive
     
    uHu likes this.
  10. uHu

    uHu Well-Known Member I am in sri_lanka

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    Good storytelling. Great work.
    One bleed nipple on each actuator. Plus one on the cylindrical accumulator.
     
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