I have a '99 GS400 with ~260k miles on it.
The front and rear springs / struts need replacing.
I have heard people complaining that aftermarket replacement units often have different spring rates than stock even when sold as direct replacements. Does anyone have any experience with this, or have a recommendation as to a good brand?
While I'm into it, what other suspension parts should I replace? (Lower ball joints, caster arm bushing, etc...?)
Does anyone have an exploded view of the front suspension?
Thanks

 

Link to the factory service manual. There's a section on suspension with all the diagrams you could needl: https://charm.li/Lexus/1999/GS%20400...d%20Diagnosis/

Do you want to keep the suspension original? Because you don't necessarily have to replace the springs if nothing is wrong with yours. For struts, KYB Excel Gs are suitable as an OEM replacement. I put those on my last GS and they rode fine. https://www.rockauto.com/en/catalog/...k+/+strut,7556

If you want to upgrade/mod, then there are plenty of other options and an entire thread dedicated to suspension setups.

Ball joints are recommended if they haven't been replaced in awhile. They're a known failure point on our cars (not that they can't fail on any other car either).

As far as the rest of the suspension, that depends on the condition yours are in, how long you plan to keep the car, and how badly you want to restore the original quality of your ride. Are you experiencing any particular noises or vibrations that may indicate worn out suspension components?

 

I strongly suggest searching and browsing the many threads that have been made about these cars' various suspension issues. You will find all your answers and more. Start with the FAQ and "sticky" posts pinned to the top of the forum section.

 

Hi Jon, Thanks for the repair manual link!
I want to keep the suspension / ride stock. This is my favorite of all the cars I have owned so I plan on driving it into the ground except that if / when the engine goes I'm not willing to sink any real $ into it given the price of gas.
The rear springs are certainly shot and I think the also the front given the ride when I have four passengers. I have a "clunking" noise from the front when going over dips / bumps, particularly when turning.
I have bad outer tire wear on both fronts (too much tow in / bad camber?) However, I had it aligned when I first got the tires and again ~20k mi latter. I'm thinking that given the mileage and if I'm going to tear into it anyway, maybe I should go ahead and rebuild the suspension.

 

Thanks for the tip Firelizard. I didn't find anything in the stickys regarding spring rates of aftermarket spring / strut assemblies.