Bouncing BX

tomsheppard · Post by **tomsheppard** » 20 Feb 2003, 14:50

When My BX estate is heavily laden, it rides like a magic carpet. When empty, it is a pogo stick. Has anybody any clues as to what may be wrong? The front struts are tired but supple on the road and the rear does not sink quickly.

alan s · Post by **alan s** » 20 Feb 2003, 16:50

Wrong spheres, possibly in the rear??
Alan S

DLM · Post by **DLM** » 20 Feb 2003, 18:27

How do both ends react to the good old "bounce" test unladen? Should give an indication of sphere health, if not suitability.
Does the rear move up and down smoothly through its travel? This can normally be tested without fear of hernia by pushing down/pulling up/gently bouncing using rear bumper). If it won't move through complete travel easily then STOP pretty damn quickly (see hernia reference above). Restricted travel could possibly mean rear arm problems, assuming spheres are correct type and in good shape.
Does the front end bounce around too?

tomsheppard · Post by **tomsheppard** » 20 Feb 2003, 19:50

well, The front behaves fairly normally although on some occasions it is hard when I sit on the front bumper. a bit of silicone grease on the struts usually helps that to go away. The rear has a fine checking system. I stand on the towbar and the car sinks, then lifts up again about 30 seconds later. When I jump off, the back end lifts before falling again.

DLM · Post by **DLM** » 21 Feb 2003, 01:04

OK - so the height correctors are definitely working, but what about what your spheres are there for - to act as the shock absorbers in the system?
How does the car react to a vigorous push and quick release on each corner?
I'm aware that most BX front struts and rear cylinders aren't what they used to be now, but if they and the spheres aren't doing their job then all the height correction in the world won't help much when it comes to comfort......
On the other hand, you could always keep something heavy in the back most of the time to make sure you keep the rear brakes well-exercised.

alexx · Post by **alexx** » 21 Feb 2003, 17:17

Height correctors don't affect the ride themselves, but the ride height must be correct. Otherwise, suspension arms will frequently hit bump or rebound stops, and the ride won't be good.
Next thing to check are rear arm bearings. If worn, they affect ride also. At least in my case they did.
And finally, check if you have the right spheres. You can also try a different kind. I wasn't satisfied with the ride in my BX (hatchback), so finally I fitted GS spheres on the rear, which have, as it turned out, significantly lower damping. Now the ride is fine, so now I'll keep it for a while.

tomsheppard · Post by **tomsheppard** » 21 Feb 2003, 17:30

Logically, the rear bearings are in the same place laden or otherwise due to the self levelling. Weight in the tail smooths out the ride at the back. This suggests that the doseur valve could be the villain of the piece because this is the only component that has physically moved.I am on the point of getting new spheres for the back and then trying some Hydraflush to see if that helps. I just like to have a solid and explicable diagnosis before I spend money.
Update: I have drained a little Vulcans' blood to find that it is a fine neon green. no immediate need for Hydrorincage then but there is a good bit less in there than last month. The float is at the bottom ring but there is no visible leak. While the beast is on tiptoe, shove on the rear corners and the nearside is weighty but smooth the offside is r-i-g-i-d rigid! Has it popped after being heavily laden? Would that explain the "loss" of fluid and which new spheres give the comfiest ride on an estate, mine being '92 vintage?
Edited by - tomsheppard on 21 Feb 2003 13:06:40

alexx · Post by **alexx** » 21 Feb 2003, 19:11

In my opinion, dosieur valve can't cause the hard ride. In released position, it's closed. Well, almost. If old, it may be internally leaking a bit, but that has nothing to do with ride comfort, as far as rear height corrector maintans correct height.
About LHM, my father has 15+ year old LHM in his GS and the ride is perfect. With years, LHM gets dirty, which can cause various problems, but it's viscosity doesn't change in such an extent that you would feel the ride is different.

DLM · Post by **DLM** » 22 Feb 2003, 00:18

A "popped" sphere can cause the lhm levels to go down quite dramatically - and also causes what someone described to me as "Green lucozade". Had a dose of this recently when changing a front sphere that semed to be [providing only minimal damping. Despite leaving the BX for a couple of weeks unpressurised before changing (wasn't using it), I still suffered a considerable and messy outburst of fizzy lhm. I'd tried to change the spheres before, then abandoned the job after finding the sphere in question was VERY reluctant to rotate even after initial cracking - a great rarity on spheres.
Sturdy plastic bags and plenty of absorbent material are an absolute must if you are changing spheres and have suspicions of this! You MAY see some fizzing lhm returning to the reservoir if you take the top off, then lower the height lever and observe what returns - though the bubbles seems to have a considerable talent for remaining in the sphere area. Could get tricky in the rear as well, with the extra complications of cylinders which you don't want to revolve.

tomsheppard · Post by **tomsheppard** » 24 Feb 2003, 13:55

I tackled the job on Saturday afternoon having cleared out the garden shed and thus gained time off for bad behaviour. Lifted car and secured it. Hammer and chiseled the living daylights out of the spheres until they appeared to move a little bit. With new ones to fit, there was no need to be fussy about the old ones. lowered car fully and couldn't reach spheres so I lifted the car again and then deflated it when it was up on the jack. both spheres came off easily. The ruptured sphere squirted loads of Vulcans' blood around. The other didn't. New spheres on finger tight, I started the car up to remove the axle stand and it lifted almost immediately. Bouncing on the towbar, the car behaves like a BX should. The ride is much better and the steering is a lot less twitchy.The tail does not sink overnight either which bodes well for the rest of the system. Almost makes me want to find a pair of old front struts to rebuild!

Thank you all very much for your advice guys.