I recently replaced the globes on my 200 series (former 100 series owner) and there's been some really detailed discussions in this thread about globes I'm hoping to piggyback on. The globes themselves are basically unchanged between the models, just different pressures and some small interface changes.
My original symptoms were the same sort of uncharacteristically 'rough ride', however after replacing my globes:
1. It now takes 30 seconds or longer to go from L -> N. Moving from N -> H goes quickly (~15 seconds, in spec).
2. The ride feels more confident but small cracks in the road still send shudders through the cabin, steering wheel, etc. I.e. little improvement.
Q1: 'Do gradations indicate healthy globes?'
The gradations measure the amount of fluid entering the system and are usually discussed as:
1.
Low gradation count indicates that fluid is not being 'pushed back' into the reservoir by pressure in the globes. The globe has lost all pressure or the diaphragm has ruptured.
2.
High gradation count indicates 'healthy' globes as the diaphragm expands when line pressure is reduced and forces fluid back into the reservoir.
Can there be a 3rd scenario such that:
1. Pressure in the sphere is
great enough to return fluid to the reservoir and results in a high gradation count.
2. Pressure in the sphere is
low enough that the diaphragm 'bottoms out' on the globe chamber and provides no spring.
In the 3rd scenario you wouldn't be able to check for a 'bad' globe with a pencil test, because there is sufficient pressure in the globe to resist the pencil, and you'd have to have a method to directly measure the pressure to be sure.
@IndroCruise I think you made some points along these lines as well, any thoughts here? My gradations are in the healthy range (>5 for the 200 series reservoir).
Some illustrations with sample values, PG = Pressure Globe, PL = Pressure Line:
Normal neutral setting, the line pressure pushes the diaphragm into an 'ideal' location for spring action.
View attachment 3394592
Normal low setting, the globe returns fluid to the reservoir as it's pressure exceeds the line pressure.
View attachment 3394593
When globe pressure is low, i.e. it will return some fluid but is bottomed out, no spring.
View attachment 3394594
Q2: Where is all this fluid going during my L to N lift?
Monitoring my pump pressure during my low to neutral transition I see a kind of plateau at about 3.5-5 MPa. This indicates the pump is building pressure but the vehicle is barely moving at all. A couple of things might be happening:
1. The pump is building pressure very slowly, i.e. reduced flow rate somehow.
2. The volume inside the system is changing, this should be somewhat expected because the globe membranes are being pushed back.
3. There is something compressible besides the globes, like a big air pocket, hiding somewhere in the system.
Considering #1 above, the system seems to build pressure for the accumulator in a reasonable amount of time and the time from N -> H (albeit with help from the accumulator) goes perfectly smoothly, even after the kick from the accumulator.
Considering #3 above, I've bled the system countless times, reversed it onto ramps to raise the reservoir to a higher point, but no significant air ever seems to come out (the only air I think I see is probably bubbles forming from the fluid entering my bleeder tube). However this seems like it's always a possibility, so I'll keep it on the table.
Considering #2 above
I'm hoping to find a way to rule this out. After I replaced the globes I stupidly threw out the old OEM ones (my car is only 48k miles so they might have been perfectly fine), so I can't easily isolate the new globes as an issue.
@suprarx7nut Your test bench for determining globe pressure is really interesting, any luck with that?
. In both cases the thread OD measured 6.7mm and the seat tapers appeared very similar, not identical, but I suspect a damper assembly bleeder would seat properly under pressure if used in the height accumulator and vice versa. You could probably drill, say, to 5mm without damaging the height accumulators thread. A 4mm or 5mm reverse twist drill would be my choice. Spot heating the broken stub might be OK but I definitely wouldn’t heat soak the height accumulator body as you’ve got hydraulic fluid, a solenoid and a 1000psi of nitrogen in close proximity. The less then perfect, but functional, work around would be to leave the busted height accumulator bleeder stub in place and just bleed around it by letting the accumulator discharge its fluid content during a raise cycle and turning the vehicle off before the pump starts to recharge it (then siphon off and bleed down to the bump stops) or by using Techstream utility you can activate the height accumulator multiple times and it will discharge back to tank where you can siphon off and bleed down to the bump stops. Either way you’ve discharged the old fluid out of the height accumulator.”
