i found that there isn't a lot of coverage regarding air suspension setups for the LS400, though the install is pretty straightforward. the following will briefly describe my adventure installing a system in my 97 UCF20. my parts list: - BC Racing BR-type coilovers - Universal Air Suspension Aero Sport bags w/brackets - 1/4" airline - SMC 3/8" valves - dual Firestone compressors - 5gal chrome tank - Norgren water traps - Viair 165/200psi tank pressure switch - Air Ride Technologies digital gauge (made by Dakota Digital) - Dakota Digital pressure senders - EAI switchbox since i am running dual compressors, i utilized a 4 gauge power wire which needs to run from the battery to the trunk. i found a main harness that enters the cabin located behind the front fender. this was the perfect spot to get the wire through the firewall. i ran it under the door sills. the rear seats need to be removed to go through yet another firewall to the trunk. i opted to drill a hole in a plastic cover neat the seatbelt. i preran my wires for my digital gauge and switchbox which reside under the center console and under the passenger side seat respectively. i ran their wires on the passenger side of the car, again under the door sills and through the rear firewall. speaking of digital gauge, i opted to place it in the ashtray which fit perfectly. i don't have any details on this part so i apologize. i had to make sure the wires don't bind when the door is pivoted. the center console is very tight so the wires were ran with caution, so much as to not hinder the cupholder hide movement.
i removed the rear trunk liner to gain better access. there is a sharp part of the frame on both sides that i covered with loom to prevent any chaffing on the wires. an exposed wire will cause a short, or worse the adjacent gas tank to catch on fire! after some thought i chose to run a new floor to hold the tank, while the valves and compressors would reside where the spare tire used to be. i used some plywood scraps from home depot. i wrapped the wood in black speaker cabinet carpet. i should have ordered dark gray instead for a better match. i highly recommend V&S 1081 adhesive over 3M. this stuff works better, especially when tackling a headliner.
next was to build the valves. since i used these valves on my previous car they were already 90% assembled. i simply needed to add extra fittings for the pressure senders. these were sourced from home depot as well. here is how the valves are plumbed where the vertical valves are for dump. after the adhesive had dried, the valves, compressors, relays, etc were installed onto the wood. now to the coilovers! it is as simple as replacing the springs with the bags, with some slight perch height changes. the bag brackets i received from UAS were bare metal. i could have used spray paint but wanted a more durable finish so i had them powdercoated matte black. i even redid the studio/battle version adjustable toe arms in the same finish. when installing the brackets to the coilovers, i used some threadlock sealant though it may not be necessary. i added a flat washer to minimize marring the finish. i removed the springs from the coilover assembly and lowered the perches 4" from the end of the shock body, per recommendation of UAS. i then put together the whole bag w/bracket assembly onto the shock body. the parts removed were the spring, the two plastic spring isolators, and the dust boot as seen in the top of the picture. here is the stock rear versus the new setup. i ended up lengthening the coilover 2" more when i installed it in the car since it was too short. the coilovers were originally intended for a 90-94 UCF10 so this may explain the difference. i failed to take pictures of the coilovers on the car. next was to run the air lines. here is the front passenger side line running down and into the underside wiring tray. there are two trays, one on each side running from the front to the back. they make running the lines much easier and symmetrical.
i routed the air lines around the exhaust behind the heat shields, above the axles, and into the trunk area using existing holes plugged up by a rubber grommet. there is one on each side near the ABS sensors. it is ideal to run the air lines the same length between left and right so the same amount of volume can move in and out of the bags. finished all the wiring to the valves and senders finished wiring the compressors and relays, one per compressor and a third one for accessory power i grouped all the grounds together to a single wire. you can see the type of compressor i'm running as well. this is the same compressor that Air Runner uses. there is a nice ground point behind the trunk liner on the right side of the trunk latch. last step was to plumb the tank. tank feed side tank pressure switch side (which was disconnected prior to testing)
here are the initial aired out pictures. the upper a-arms are hitting the frame up front. i am unsure what is stopping the rear. i have yet to take a test drive and play with the dampening settings on the coils. from factory they were set to 25 front 25 rear (30 being the stiffest). i brought the rear to 20 for now. also i am uncertain as to what bag pressure feels and works the best. i may have to adjust the height settings on the coils to lessen the strain on the bags especially up front. i haven't even checked for leaks!
here is some followup information that i thought was valuable. why did i run these valves? i already had these valves from my previous setup and they work great. why spend more? the SMC valves are made in japan and are rebuildable (at the cost of deplumbing everything). why not accuair or autopilot? cost is precisely why i stayed away from accuair, autopilot, etc. i love the manifold valve setups but i just couldn't spring the money to get one. they would have made the install much easier and cleaner for sure! what will i do in case of a flat? in case of a flat i simply call AAA. even if i had a spare, i just have it towed. i'd rather not deal with that on the side of the road. risky i know. are 1/4" lines too slow? i ran 3/8" lines before in my other car and it was too fast so i told myself i would run 1/4" this time around (my comparison is a boba straw vs a regular straw). i had to run speed controls to slow it all down, since it was hopping up (this was on a much lighter accord)! glad i went smaller since i feel the speed is very nice and controlled. i am running 200psi tank pressure where most folks run at 150-175psi. also running 1/4" lines through the car is much easier since it's smaller and more flexible.
[FONT="]the wheels i already have, just need to save up for the tires and massage the fenders a bit. you can see the wheels stacked in the background when i was doing the carpet installation (tease).[/FONT] [FONT="] [/FONT] [FONT="]here is a pic when i took her on her maiden voyage this morning. i found that running 90psi up front and 45psi out back works well. it's pretty stiff so i'll adjust the dampening. there is also some knocking coming from the rear. i suspect the top hats. so far the pressures are holding constant![/FONT] [FONT="][/FONT]
nice diy!!! i love it when people take the time out of their install to snap a couple pictures. i try to when i do installs and such, but when things start going the wrong way, it starts becoming frustrating and you're just trying to finish what you're doing.
I´m not a fan of air, but this write-up is great !! I used to have the same set up, and the ride was super! BTW, check the rear lower coilover body: at 0psi it rubs against the upper arm. SS kit solves the problem.
exactly! i just wanted to finish so i continued on then at: when i forgot to take pics along the way. i forgot to take pics of all four bag/coils and them installed in the car! when i check for leaks i'll take more pics. that's my goal! the LS400 community is growing as the car is getting more affordable so i would be happy to aid in anyone trying to do this themselves. i appreciate that! i still feel it's lacking a few details that may answer those common questions. yes!!! i suspected that when i was installing them and simulating suspension movement with the jack. thank you for the clarification. now to find an SS kit...
Thanks for this post, we are doing by bros car next week and i was concerned on how the bags mount to the struts, i appreciate your detailed write up, thanks again!!!
