I've noticed that the common trend is to replace or upgrade bushings on the rx-7 rather than to replace the various arms that come with upgraded ones. The advantages in replacing the suspension arms would be adjustability, strength, easy installation, and killing two birds with one stone with the new bushing.

Is it a cost issue? Or lack of availability in parts? Perhaps I'm missing something.

 

Well, the stock FD suspension has excellent adjustability and geometry. The weakness is the worn-out bushings and/or pillowballs. Aftermarket toe links and trailing arms are very popular, and definitely an upgrade, but since you're talking about arms with bushings I assume you're not talking about these links.

I see upgraded suspension arms cost several times more than the pillowballs and bushings do. So unless you're looking for a super low drop or extreme amounts of camber, I suspect most FD owners simply recognize it's a lot of money (and lead time) for adjustment that won't be used.

 

Adjustability often just provides you with more ways to adjust it wrong.
Camber, caster and toe is readily adjustable on the FD so you normally don't need adjustable suspension arms unless its a total race car where a modified suspension geometry might be needed or desired to get those last few 10ths.

Strength of aftermarket arms is debatable since I doubt they have been tested as stringently as the OEM pieces and the OEM suspension arms have been proven to be strong and live up to the task.

The stock arms install easily so I don't understand what you are trying to get at there...

Cost is definitely an issue as they are either custom made or imported from some Jap tuner at major $$.

What you are missing is more experience with the FD and an understanding that the chassis is really well engineered out of the box.


Now, if you were talking about buying the a new stock suspension arm rather than replacing just the individual bushings in that arm, yes it makes sense on some arms - particularly the front upper control arms and rear upper control arms. It can be cheaper to buy those in one piece rather than buying the bushings independently and labor on installing the bushings.

 

What advantage really is there to new arms? Stock arms are plenty strong and rarely or never fail. Stock toe links are just as adjustable as aftermarket ones, and there is no need to adjust the length of the trailing arm bushings. There are bushings with eccentric pins for the UCAs if you need more camber adjustment. Heim joints can wear faster than bushings and can transfer more vibration and noise. So it may be a little more work to install, but you are paying a lot more for shiny parts.

 

Thanks for the responses. Indeed I do need more time and experience with the fd chassis. I was looking for experience with those with and I'm not disappointed.

What I meant by 'ease in installation' was avoiding the whole trouble of pushing out/in the bushings by installing a replacement with one already in.

My car feels a bit squirrley and unstable. I'm by no means pushing it and I do have quite a few hours of track time under my belt under a different vehicle. With that in mind, I'm contributing it to the bushings rather than the (newer) tein flexs that came with the car. Sound about right?

 

Probably.

Have a read at Howard Coleman's suspension thread - he might be the super-guru of FD suspension w.r.t. track and street setups:
https://www.rx7club.com/suspension-wheels-tires-brakes-20/howard-colemans-fd-chassis-setup-723617/

 

I started last night, thank you!