Spheres, Hydraflushing and Brake Bleeding

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A question that is often asked is how to replace spheres, how to change the LHM, use Hydraflush and bleed brakes. This is a (hopefully) a concise guide to these three related jobs. I post here so that comments may be added and "peer reviewed" before it is moved to a more appropriate area of the forum.

Pre Requisites

Before starting, ensure you have the following:

Parts

  • New spheres
  • A 4.5mm hydraulic seal for the Anti-Sink Sphere

Tools & Sundries

  • A good sphere removal tool. Either the genuine Pleiades item or a "Xac Special" A tool is essential
  • Ramps and axle stands
  • A 12mm spanner for the bleed valve on the pressure regulator,
  • A good 8mm hexagon socket and a good, slim, 8mm ring spanner for the caliper bleed nipples
    Brake Bleeding Kit
  • very high quality 9mm flare nut spanner for the union on the anti sink sphere.
  • A clean 500ml glass jar and a length of plastic hose that is a snug fit on the bleed nipples; or
  • 300ml (dry) 'water' bottle and a length of plastic hose that is a snug fit on the bleed nipples.
  • A jar or 'water' bottle of clean petrol and a clean ½” paint brush for cleaning the LHM filters.
  • A normal household broom (you'll see why later!)
  • Bottom halves of several large plastic (milk) bottles to catch LHM, drain spheres and wash the reservoir filters.
  • A cheap plastic kitchen jug (½L) or a new oil jug to fill the reservoir without spilling LHM everywhere.
  • Lint-free rag or quality kitchen roll.
  • Plus-Gas.

The 'Brake Bleeding kit' pictured consists of 1) plastic drink bottle with two holes drilled in the lid that are a tight fit in polythene pipe that is itself a snug fit on bleed nipples. The longer (bleed) pipe goes to the bottom of the bottle, the other (suck/blow) pipe for siphoning goes just far enough (an inch or so) through the cap to stop it popping out. 2) a 2L plastic ice-cream/margarine tub with lid for drainage, washing of filters and clean storage. 3)Cheap plastic kitchen ½L measuring jug.

Spheres

Starting with the most difficult, the rear corner spheres. These are often very tight and their removal MUST be carried out initially with the suspension on high and under full pressure to avoid damage to the suspension cylinders. The car MUST be very firmly supported and preferably on ramps. In any case, so supported that if it suddenly drops it won't crush you. So, up on ramps, engine running and suspension on high, you need to apply the sphere tool and "crack" each sphere off by about an eight to a quarter of a turn (i.e. just get them started). They will be tight and you may need to use your boot to get them moving. Once they are moving, put the suspension on low, de-pressurise by opening the 12mm bleed valve on the pressure regulator by no more than half a turn and go back, still ensuring the car is fully and safely supported and unscrew them fully. Be prepared for LHM spillage. Clean up, recover the old sphere seals if they got left behind in the groove on the sphere housing. Get your new sphere seals, dip them in clean LHM and place them in the groove, never place them on the sphere as they will not seat properly and may get cut. Screw the new sphere on hand-tight only.

Whilst you are there, do the Anti-Sink sphere.
Anti-sink Sphere.jpg
This is the one in the middle rear. before you can unscrew it, the small hydraulic pipe going into the rear of it MUST be undone and pulled out. For this you need the 9mm Flare Nut spanner. The union may be tight and take care not to round it off, hence the good spanner. A bit of Plus Gas is a good idea to help it along. Once the union nut is undone, pull the hydraulic pipe out of the sphere and note if the hydraulic seal came out with it. More than likely it will have stayed in the sphere. You MUST use a new one on installing the new sphere. Again, be prepared for a good spill of LHM.

You can now undo the old sphere off the bracket. It may be tight and the bracket is not that strong so take care. Strictly, this sphere does not need a new ring seal but it's not a bad idea to fit one. Screw the new sphere into the bracket, dip the new pipe hydraulic seal in LHM and fit it over the end of the pipe until it rests against the flare on the pipe. Push the pipe into the sphere and screw up the union. They don't need to be done mega tightly and it'll be about right when it is as far into the new sphere as it was in the old, usually thios depth can be gauged by where the rust begins on the union threads. On repressurising the system, check for leaks and if there is a weep, just nip the union up a touch until the leak stops.

They're the hard ones done. The front corners are easy, Just undo them (with the system on low and depressurised of course) be prepared for spillage, clean up, dip the new seals in LHM, place the seals in the grooves and screw the new sphers in hand-tight.

The same applies to the accumulator but access is often poor and you really need the front end up on ramps or stands to get good access to it to enable a good swing on the removal tool. The Accumulator is often very tight. Mind the radiator! Again, clean up, Dip the seal in LHM and place in the groove before screwing the sphere in hand-tight.

Finally, nip up the 12mm bleed valve, start up, allow pressure to come up, set on high, top up the LHM and do a really good session of Citarobics.

LHM Change

  1. Set on low, depressurise, disconnect all the rubber pipes on top of the LHM reservoir. If the original clips are in place, carefully prise them apart with a scriber or small screwdriver before pulling the pipes off. They can be reused with care and need a small pair of pliers to clip them up again.
  2. Undo the two 10mm nuts holding the reservoir and lift it out full of the old LHM. This is the easiest way. Release the spring clip across the top, lift out the filter head and place it in a clean receptacle to drain. I use the bottom of a 4 pint milk carton.
  3. Pour the old LHM into a suitabel container ready for disposal at your local tip. Use the waste engine oil facility.
  4. Clean out the LHM reservoir with clean, lint-free rag (blue paper is ideal) and them remove the two filters from the filter head and clean them in petrol. One is clipped on and is secured with a small "S" shaped wire clip and the other is secured with a bayonet fitting and is long and conical. It is easily missed as it lives up inside the suction tube. Wash them with a paint brush in petrol until they are spotless and leave to dry. The filter mesh is delicate so don't be rough with them.
  5. Reassemble the LHM reservoir and refit to the car. The clips that hold the pipes on to the reservoir can be reused with care or "Jubilee" clips can be used instead.
  6. Refill the reservoir with either LHM or Hydraflush. It'll take at least 4 litres.
  7. Close the pressure regulator bleed valve, start up and set the suspension on high, top up the reservoir and do thorough citarobics. Recheck the level.

Bleeding Brakes

With the front wheels off and up on stands, locate the front caliper bleed nipples. Pop off their protective rubber caps, clean up around them, spray them with Plus Gas and carefully crack then open with your 8mm ring spanner. Nip them up again. leave the spanner on and place the plastic pipe on the nipple and lead it into a jamjar. Start up and apply the brakes by jamming the end broom between the seat and brake pedal (now you see what the broom is for!). Open the bleed nipple and watch LHM run ito the jamjar. When free of air and all the old, dirty fluid is flushed through, nip up the nipple, slip off the pipe, replace the rubber cap and repeat on the other side. Top up the LHM reservoir with the equivilent amount you bled out.

The rear brakes MUST be bled with the suspension set on high and with weight on the back wheels. On cars with alloy wheels it is sometimes possible (depending on the wheels) to get at the nipples without removing the wheels but on most, the wheels have to come off and that makes a problem of how to keep a load on the back wheels. Best is to do one wheel at a time and keep the other on the ground and thus loaded.

Do the same as for the front but do bleed at least 250mL of fluid out of each nipple as the rear brake lines are very long. Keep an eye on the LHM level and top up as necessary. You will know the level is low as the STOP light will come on. Don't let the level drop too low.

Job done. If you have used Hydraflush, leave it in for al least 1500 miles and them change for proper LHM it by repeating all the above procedure, including cleaning the filters again.

Recheck levels and do citarobics again.

Job's a good 'un

Please add to this as I'm sure to have forgotten something!

[Edited to correct the A/S sphere union nut size and hydraulic seal size :oops: ] [Edited to add some extras to the list of pre-requisites]