Start with a free and fast adjustment of the front torsion bars. Increasing the pre-load on the fronts normally removes some pressure from the rear as well. You're WAY over spec in the front, so you'll have a lot of turning ahead of you.
replacing AHC globes/accumulators (2 Viewers)
- Thread starter pete100
- Start date
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Driver's side is already almost maxed out...but pass side is not. Not out of the realm of possibilities I might need new T/B's up front. But I will look at all of that when get around to doing the globes and rear springs.
I've got 235K on the vehicle now and its all the original suspension except for all the front end work done recently. I also need to educate myself on setting pressures and how that is achieved. To date I've made cursory readings of some posts....but not taken the time to fully understand it all.
I wouldn't get new tbs, but your call. Just reindex if needed. With those pressures, I wouldn't be surprised if the bar or bars were improperly indexed previously.
Just reindex a tooth if you run out of adjustment. Quick and easy.
For AHC and pressures: turn torsion bar bolt clockwise to lower pressure. That's it. If left side is high, turn right side clockwise until you're even.
If you were able to read pressures, you've already done the hard part.
^^^^^^I wouldn't get new tbs, but your call. Just reindex if needed. With those pressures, I wouldn't be surprised if the bar or bars were improperly indexed previously.
Just reindex a tooth if you run out of adjustment. Quick and easy.
For AHC and pressures: turn torsion bar bolt clockwise to lower pressure. That's it. If left side is high, turn right side clockwise until you're even.
If you were able to read pressures, you've already done the hard part.
Ahhhhh.....good reminder, I had completely forgotten they can be indexed to an extent.
This vehicle prior to my ownership was 'lady owned' and driven, Houston area....so mostly freeway use, always garaged, dealer serviced. No off-road that I am aware of, no accident reports except for minor bumper rashes. So probably a good candidate.
I will look into that. Thanks for bringing that up, had forgotten.
To assist @AFei, here is a cut-away cross-section of "Mount Rushmore" (acknowledgement to an unknown IH8Mud Member). Note 'globe' wall thickness compared to threaded connector to get an idea of scale. Wall damage is improbable so if all else fails, suggest strike the 'globe' a few times to create an indent which might give you some purchase, or maybe even cut or grind one or more small grooves, then strike in such a way with a hammer and cold chisel so as to cause the 'globe' to rotate counter clockwise -- the idea is to avoid too much bending at the finned Actuator where the 'globe' is attached -- don't want any breakage at the Actuator although it also is pretty robust as it is constructed to deal with the same internal pressures as the 'globe'. Quick strong repetitive blows usually are better than a 'king hit' -- vibration is good when trying to break open a thread. Strongly recommend using good workplace eye protection during these activities ....
Wow, amazing picture. It really explained everything. Thanks for the great advice that "Quick strong repetitive blows usually are better than a 'king hit'"! Really helpful...
Alright, update- my new globes showed up this morning from Impex and I will be swapping them tomorrow afternoon since weather is supposed to be much nicer. FedEx soaked and beat the hell out of the box but each globe was individually packaged and seemingly undamaged. Will report back results.
BullElk
SILVER Star
@IndroCruise, do you know if the location and shape of membrane in picture is accurate in a good globe?
Good question @BullElk!
Short answer: It is not known whether the picture attached to Post #205 above represents the membrane position in a good ‘globe’.
Long Answer: It seems likely that cutting process involved making the cutaway would have had a tearing effect on the rubber-resin-rubber sandwich which makes up the membrane. Nevertheless, I think the membrane in the cutaway is in its natural, as-manufactured position, without the effects of nitrogen gas on one side and AHC Fluid on the other side.
The position shown in the cutaway is similar to the position shown in the diagrams in the FSM.
I have a set of old ‘globes’ – two Front and two Rear – so I measured them this morning and marked-up the measurements of their membrane positions on the FSM diagram below.
However, the marked-up diagram is illusory because, while the measurements are accurate, the measurements on the amended diagram are not to scale and do not show the distended membrane position accurately, as caused by the residual nitrogen gas. So this exercise really does not tell us much.
The old ‘globes’ came off my vehicle when the HI/LO Test showed 8 graduations. Even though the FSM says that this is the change-point for Australian vehicles (versus 7 graduations elsewhere), I could have left the ‘globes’ in place for longer. However, we were preparing for a long trip of ~6,500 kilometres (~4,000 miles), some of it along hot, rough, remote roads and trails across Australia while heavily loaded -- and so I decided on a precautionary early change-out of ‘globes’. We had a great trip without any mechanical dramas – but that is another story.
The point is that the old ‘globes’ still have considerable nitrogen pressure. The membranes in all my old ‘globes’ are visibly and measurably pushed way towards the fluid entry by this pressure. I would have to release the nitrogen pressure to see how the membrane position really compared with the cutaway picture. For now, I guess I will keep them 'as is' as a back-up set of ‘globes’!!
View looking into fluid entry of old 'globe' showing distended membrane pushed forward by residual nitrogen pressure. It is likely that new 'globes' would look very similar out of the box.
BullElk
SILVER Star
^^^^ Excellent.
Like I mentioned in another thread as I semi-tested out two old globes. I pushed on the steel "membrane" shown in the fluid entry pic above. One moved a bit and one did not move at all.....so I kept and reused that one.
Like I mentioned in another thread as I semi-tested out two old globes. I pushed on the steel "membrane" shown in the fluid entry pic above. One moved a bit and one did not move at all.....so I kept and reused that one.
So tried following the video @suprarx7nut produced, and here is the result.
All the following measurements were taken with normal load in the car, without any people in the car.
1. Baseline after disconnected the temperature sensor:
- FL is 0.2 inch lower than FR;
- Front Pressure: 7.5 Mpa
- Rear Pressure: 6.9 MPa
- Accumulator Pressure: Not readable
- Gradation test: 6 steps
- "As-Found Heights":
- FL 481mm or 18.94"; FR 486mm or 19.13" ==> L-R: -5mm or -0.2"
- RL 502mm or 19.75"; RR 512mm or 20.16" ==> L-R: -10mm or -0.4"
2. The first thing I changed is to try to cross level between FL and FR.
So I cranked the Driver side TB adjustment bolt 2.5 CW turns.
- FL is level with FR;
- Front Pressure: 7.0 Mpa
- Rear Pressure: 6.7 MPa
- Accumulator Pressure: Not readable
- Gradation test: didn't test
- "As-Found Heights":
- FL 485mm or 19.09"; FR 485mm or 19.09" ==> L-R: 0mm or 0"
- RL 507mm or 19.96"; RR 507mm or 19.96" ==> L-R: 0mm or 0"
Conclusion: 2.5 CW on Driver side corrected the front level issue.
3. So now my next step was to try to bring the front end "As-Fount Height" to in spec of 19.75".
So I cranked the Both sides TB adjustment bolt 6 CW turns.
- FL is level with FR;
- Front Pressure: 5.5 Mpa
- Rear Pressure: 6.7 MPa
- Accumulator Pressure: Not readable
- Gradation test: Over 11 steps!
- "As-Found Heights":
- FL <485mm or 19.09"; FR <485mm or 19.09" ==> L-R: 0mm or 0"
- RL <510mm or 19.96"; RR <510mm or 19.96" ==> L-R: 0mm or 0"
- As expected:
- Front pressure decreased for about 1.5 MPa
- Unexpected:
- 6 full CW turns on both TB didn't change the height between fender bottom and the wheel hub center
- Gradation test increased from 6 steps to over 11 steps!
Questions:
- How could it happen the gradation test is dramatically better after cranking the TB? Does it mean the globes are actually good, even the car is over 200K miles? How could it possible for that happen?
- How come the height didn't change, but in fact a little bit lower at 4 corners, after 6 full CW turns on both TB?
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I'm guessing your 11 step test included filling of the height accumulator. I haven't heard of pressure changes making that big an impact. A tick or two, sure, but not 5.
Can you try again and make sure that you see accumulator pressures before and after? You may need to let the car sit and idle for more than 60 seconds after any height change. When you see 0.0 in techstream for accumulator pressure it means the accumulator has yet to fill. It must be filled during both the before and after checks of fluid levels.
Regarding height change: torsion bars have ZERO effect on ride height in the AHC system. AHC maintains ride height based on the sensors. It will acheive as close to 0.0 as it can and it uses the mechanical springs/torsion bars in combination with the hydraulics. When you adjust torsion bars on AHC, you are modifying how much load is carried by the mechanical springs and therefore, how much additional force is needed from the hydraulics. More force from hydraulics is seen in the higher neutral pressures.
The first time I didn't see the accumulator pressure was after disconnecting the temp sensor. Would that be related?
Yeah, I will try again today after work.
This makes sense to me. However, I saw Driver side -0.2" and Psngr side +0.2", if I sit in the car. I guess it also make sense, since it's the same pressure between both side?
So to bring the ride height back to spec, like 19.75", the only way for front is to adjust the height sensor? and how about rear?
Yeah, I recall the accumulator not filling if the pressure sensor is disconnected. Plug that in for the gradation test.
And yes, to change ride height in an AHC vehicle you move the sensors. Front left and right and rear.
Final update- installed yesterday and super happy with the results. I almost feel like this dramatically lowered road noise at highway speeds as well, that was a nice surprise. All in all, really happy I decided to do this and a big thank you to everyone for providing input.
How long did it take IMPEX to get your order ready for shipping? I placed my order on Sunday and haven't heard from them yet...
I placed the order on 1/26 and had a shipment request 2/1. Once I paid, it shipped two days later and was delivered on 2/8.
For me, about a week after I ordered there was a 2nd email saying the package arrived to their warehouse. Then they asked for me to select and pay shipping and estimated tariffs to the US. A few days later I received the package to Texas.
