Rear springs replacement with AHC … Challenge #3 (1 Viewer)

[Africaster]

Recap:
Bought car with semi-to-non working AHC. System will go from N to L on command, but nothing else, every pebble or crack in the road is felt … rather jarringly.
TechStream numbers for front and back were through the roof … front torsion bar and sensor adjustments brought front pressures to within almost reasonable levels and standard hight when in N …. rear pressure remained way too high, AHC system still not working, ride still jarring.

Plan:
Following the AHC refresh threads, the next step is to replace the rear springs with Kings, followed by replacing globes and fluids.

Car jacked up and frame resting on stands, rear wheels removed with much gentle persuasion, left side of axle jacked up so far that the car lifted off the left stand … but … right side of axle didn’t drop anywhere nearly as far as they do on the various YouTube vids. Switched OFF the AHC assuming it’s somehow pressure related but made no difference, that right spring is not going anywhere … am I missing a step perhaps?

Inputs appreciated

 

[ga12r1]

Disconnect AHC rams from axle and disconnect sway bar

 

[suprarx7nut]

Disconnect AHC rams from axle and disconnect sway bar

Yup. Forgot to do this myself, despite having changed out rear springs 3 times on the 100.

Gotta undo the sway bars and shocks.

 

[flipckyLC]

You have to remove the bottom nut of the rear shock and disconnect the shock from the rear axle (use pry bar). Make sure the car is jacked up high enough so your rotor doesn't bottom out.

 

[Africaster]

Thanks Gents, makes sense with hindsight … ordered replacement bushings and link assembly from PS, might as well replace them whilst digging down there.

 

[Africaster]

You have to remove the bottom nut of the rear shock and disconnect the shock from the rear axle (use pry bar). Make sure the car is jacked up high enough so your rotor doesn't bottom out.

Thanks @flipckyLC … disconnect both shocks before swopping the springs, or one side at a time? Appreciated

 

[flipckyLC]

Thanks @flipckyLC … disconnect both shocks before swopping the springs, or one side at a time? Appreciated

One side at a time

 

[yngmrostrvile]

I left tires on. Disconnected brake line bracket, lower bolt on rams, stabilizer links, and panhard. Jacked the vehicle up under the receiver.

 

[Africaster]

Went ahead with replacing the globes and fluids … went as well as one could have expected … used the chisel technique to loosen the globes - they were the originals still with the 1999 factory sticker - first bleed was frothy with dark grunge in parts… didn’t strip any bleeder nipples (bled all 5) so that was a bonus. 15 minute dance with the first one until a few gentle persuasions proved the key step, new one slid in easily … second took 10 minutes with the gentle persuasion coming earlier in the sequence … third was down to 5 minutes and a slick routine developing … 4th (FL … or drivers if you prefer) came off with no deviation to the process although it was fairly tight against a rubber covered piece of the accumulator … then came the last step, screwing the last one in … …. …. 30 minutes later and a few breaks to kick the tyres, still can’t get it to align and thread on … removed the previously mentioned rubber cap in case it’s 2mm thickness was the issue (even though it had unscrewed 30 minutes earlier) … still not seating. So after trying all other options decided to check the obvious … old globe compared against new globe … EFFING different … bottom line, the front globes seem to be approximately 1/7 squattier that the back … taking a break before repositioning … hopefully it’s just the LR which needs to come to the front.

Please let me know if my logic is flawed … tx guys

 

[Rebus Knebus]

… bottom line, the front globes seem to be approximately 1/7 squattier that the back … taking a break before repositioning … hopefully it’s just the LR which needs to come to the front.

Please let me know if my logic is flawed … tx guys

You got it, front globes are smaller. Been there, done that

 

[IndroCruise]

You got it, front globes are smaller. Been there, done that

Hi @Africaster: Sounds like success is on the way!

Good to get the protective cover back on the solenoid at the front end of the Height Control Accumulator -- nakedness will not improve the way the Accumulator works.

While under the vehicle, also suggest have a look at the connector at the Control Valve Assembly on the inner side of the LHS (your drivers side) chassis rail, pretty much opposite the position of the Height Control Accumulator which is on the outer side. This connector should have a protective shroud -- just decently thick tape will do -- to protect against projectiles such as sticks, stones, grit, salt, whatever, trying to cause harness damage at that point (see last pic below).

Also suggest check that the Rear Height Control Sensor has not been accidentally "stretched" during proceedings -- it can happen if not disconnected, or, it can try to "fold" in an unnatural position and distort the linkage and/or attachment brackets when the axle is back in place and the vehicle is returned to ground zero ......

At the end of the spring job, if the Rear Sensor looks something like the pics below, then nothing to worry about -- although I have to say that if all three Height Control Sensors are the same age as the changed-out 'globes' (22 years), then there is a fair chance that they are past their best

 

[ClassyJalopy]

Went ahead with replacing the globes and fluids … went as well as one could have expected … used the chisel technique to loosen the globes - they were the originals still with the 1999 factory sticker - first bleed was frothy with dark grunge in parts… didn’t strip any bleeder nipples (bled all 5) so that was a bonus. 15 minute dance with the first one until a few gentle persuasions proved the key step, new one slid in easily … second took 10 minutes with the gentle persuasion coming earlier in the sequence … third was down to 5 minutes and a slick routine developing … 4th (FL … or drivers if you prefer) came off with no deviation to the process although it was fairly tight against a rubber covered piece of the accumulator … then came the last step, screwing the last one in … …. …. 30 minutes later and a few breaks to kick the tyres, still can’t get it to align and thread on … removed the previously mentioned rubber cap in case it’s 2mm thickness was the issue (even though it had unscrewed 30 minutes earlier) … still not seating. So after trying all other options decided to check the obvious … old globe compared against new globe … EFFING different … bottom line, the front globes seem to be approximately 1/7 squattier that the back … taking a break before repositioning … hopefully it’s just the LR which needs to come to the front.

Please let me know if my logic is flawed … tx guys

Keep at it man, before you know it the hard work will be all done with and you will be left with a smooth riding truck!

 

[Africaster]

Firstly … thanks everyone who took the time to share their inputs in this thread and the umteen others on this site (library of Alexandria comes to mind)

Secondly …. I am an AHC God … well not quite yet, but that circle of light is now clearly not a train.

Spent Saturday successfully replacing original shocks with Kings (and threw in airbags as I’ll be towing boats and campers and other trailers … might be significant info later in this post) and all rear sway bar bushings.

Sunday, followed MD’s AHC cheat sheet methodology and was ecstatic to see rear pressures of 4.8 (pre-Kings were 8+) and 7.3 fronts … 19.5“ fronts and 21“ rears (minor diffs between sides). Cranked front torsions a zillion turns and ended up with front 20“ & 6.2 and rears 21.5“ & 5.2. Height sensors are 0 for rear, 0 for front right and -0.1 for front left (which I’m attributing to 50+ years of beer). So far so good, now to measure graduations.

BUT … center console switch drops to Low but the only way to get back to N is by driving at 25mph (fun fact, it also rises when going 25mph in reverse ). Up until this point I’d assumed the failure to rise from L-N and N-H via the switch was due to pressure issues which MD had alluded to in his 123 vid. Decided to buy a center console AHC switch control thingy to test the switch, ETA later in the week … then kept awake all night by this bloody thing, dismantled the switch this morning, simple looking pc board, traced wires and tried to bridge power with Up … Nada … Up, Down and Off push buttons on pcboard all felt fine (as did switch on panel) … connected pcboard only (not face panel) and pushed Up button … and up she rose .

Graduation marks between L and H = 15+, so all seems relatively good with AHC, will bleed a few times over the week and rerun the tests next weekend.

Still need to install the new rear shocks, but perhaps no longer a Must Do right now depending on if the ride becomes a bit more magic carpet like after a series of bleeding … still a bit more jarring than expected … maybe airbags/lack of weight in the rear/air in the AHC system? Thoughts guys?

Next is to trace what the situation is with Tilt & Trim. … oh, and I think I blew the Amp whilst installing a new rear speaker last week.