JZS140

Hey guys I'm new to this forum and pretty much forums in general so please be easy on me lol. I purchased a 92 Toyota Crown Majesta (1GS stretched chassis) that came with Tom's Racing Advox coilovers. These coilovers were never adjusted by the previous owner since the black circle on the perches was perfect and not chipped. You can tell the suspension was on the car for a while but was hardly driven due to it being so clean. I drove the car around for a few months at the height it was when I bought it, the suspension was great, and eventually decided to lower the car 1" on all 4 corners with at least an inch left to go on the rears and a half inch more to go on the fronts. Since I lowered it, it's been way more bouncy than it should based on few posts I've read regarding their performance and of course, its Tom's Racing! I've never owned a set of 1 piece coilovers so it took me a while to figure the adjustability out which was weird because it also loses the preload, hence the bounciness. These coilovers have 2 chambers, 1 for oil and the other for Nitrogen with a Schrader valve to refill. I suppose the Nitrogen is used to make up for the loss of preload because if not, how are you supposed to lower it right? If so, how much PSI based on preload loss, if that even makes sense. Maybe there's an additional helper spring that wasn't installed/included or may need if you want to go lower. Yes I have read all posts with "Advox coilovers" and I cannot find any concrete answer. Yes I've also called tuner shops in my area, used JDM parts suppliers across the U.S. and even Tom's distributor in California and nothing. Any info, specs, links etc to help me resolve would be EXTREMELY appreciated as I'm running out of places to call and websites to read.

Mandrake

When you lower these, you're actually losing piston stroke because your lowering the spring perches which in turn causes the piston to be pushed in further. The piston height isn't independently adjustable so this is unavoidable with this design. The nitrogen separates the oil and the piston. The pressure does have some effect on damping and preload but adjusting the pressure should only be used for fine-tuning, not major adjustments like what you want. You can calculate the amount of "preload" by taking the area of the piston and multiplying that by the nitrogen PSI.

Ultimately, if you want more preload, these are linear metric springs so its easy to get preload springs or just order longer springs if thats what you need. You can get these springs for about $25 each from Ground Control, Eibach etc. You just need to know the height, diameter and rate.

It sounds to me like the problem isn't with the preload or the springs, its with the length of the piston stroke. You could try getting the shocks re-valved and see if its more comfortable. If you just want to go low, a twin-tube design might actually be more comfortable for you. There's also monotube coilovers that allow the ride height to be adjusted without changing the pre-load or compressing the shock.

I know a local guy who rebuilds racing shocks and he's rebuilt a couple sets of Bilsteins for me. I could bring these in to him and see what he can do with it. He probably won't know until he takes the shock apart. If he can't make something work to adjust the valving, like if he can't find shims etc, he could probably at least change seals and adjust the gas pressure.

So I don't know what you want to do, but I'd be interested in these coilovers if you want to go with another setup. I have TRD on my JZS147 and its actually a little lower than what I see in the picture as far as the fronts go but for some reason, the rear is higher than the fronts. If you want to swap, I'm guessing it would be a direct swap since these are both a 14X chassis (JZS147 vs S140).

JZS140

I had to search around online some more before I responded back but it does look like I'll be getting rid of these Advox's. I'd be interested in swapping suspension but not sure how that'd work since we're pretty far from each other. A couple questions about the TRD's, is that as low as they go and how's the ride?

Mandrake

Can you send me a private message? I think thats just between us at that point. For the record, if anyone wants to know, the TRD suspension is firmer than stock, but not bouncy or jarring. The response from the shock doesn't seem to be quite as good as a Bilstein PSS9 but probably better than a Bilstein B10. It seems most comparable to a Bilstein B12. Its more controlled than something like a Tokico Illumina. There is a bit of a jarring noise going over speed bumps but I don't get a lot of noise from seams on the highway. If you drove the car, you could definitely tell it has a modified suspension but you might not know that as a passenger.

As far as the ride height goes, these aren't thread collars over the shock body. These are regular coil spring over the shock with a fixed perch.