TTopJohn

With 110,xxx miles it's time to replace the stock suspension. Thinking PST stock replacement (i.e. rubber not poly) front end rebuild kit, Koni S/As up front and revalved bilstiens in back (from Strano).

But what about the rear? Lots of people say LCAs, PHR, and Torque Arm are good things to get.

Besides helping eliminate wheel hop and giving you a better launch at the track, what exactly is the benefit of LCAs? I understand the theory that stiffer LCAs locate the rear suspension more accurately. But how much does this really help for cornering? And doesn't it transmit a lot more Noise Vibration and Harshness into the cabin?

In addition - i've never actually seen an aftermarket LCA that comes with rubber bushings on both ends - and I don't want any poly in in the suspension for NVH reasons.

Don't need an adjustable torque arm because I'm not lowering the rear (may drop the front 1/2 inch using the adjustable perch on the Konis).

Don't need a replacement torque arm because I have no issues with wheel hop that need correcting. (another reason why I don't think I need aftermarket LCAs)


So here's what I'm thinking - I don't need aftermarket LCAs for launching. I need to turn corners and drive on the street. Aftermarket LCAs (and PHB and Torque Arm)would locate the rear axle more accurately, but there's already a lot of stuff locating the rear axle accurately on our cars (PHB, Torque Arm, and LCAs). If those stock pieces are freshened up with new rubber bushings, the Konis and bilstiens will give me MUCH better handling than the car had when new.

Thoughts?

jRaskell

iTrader: (1)

Have you looked at all that stuff under there? There's a lot of stuff locating the rear, but it certainly isn't being done accurately. Everything under there is stamped steel, and flexible as all hell. I'm not saying you have to swap them out for aftermarket tubular stuff. You will see a big improvement from the shocks alone, but the stock parts DO induce a lot of slop in the rear suspension, even if they are freshened up. I've felt the differences myself (on my previously owned GTA). I will be making the upgrades on my TA. I understand the desire to avoid poly bushings, but doing so does come with compromises. You just shouldn't be trying to trivialize those compromises in an attempt to make the choice easier to make.

You can get good handling with the stock pieces, but you can get even better handling with aftermarket pieces. It all depends on how far you're willing to go.

John95Z28

It depends on who you ask; lots of owners will say their rod end suspension bits (like BadZ's gear) are not louder than stock, and well worth it for better cornering. Most people who want increased cornering and grip are willing risk a little increased Noise Vibration Harshness

If I understand your goals correctly, then you're probably better off to stick with the stock rear suspension bits. New rubber bushings on everything along with new shocks & springs should make your car handle better than new, with NO increase to NVH at all.

BMR makes a poly / rubber LCA, so if you wanted you could try that and just swap the poly bushing for a rubber one, but I doubt you'd be able to notice much cornering improvement in daily driving over the stock LCA. Hope that helps

Fulton 1

iTrader: (9)

TTopJohn, I think in your post you've answered some of your own questions and your approach makes sense to me.

IMO for strictly street-driven car the factory stuff (in new/refurbished condition) will do a nice job. If you want a slight upgrade with no downside then I would consider some of the 1LE parts - especially the LCA's and PHR (SLP currently has the 1LE PHR on sale for $30). I believe there's also a list of 1LE GM part numbers floating around here somewhere. These are factory parts that use slightly higher durometer rubber bushings to provide a bit more rigidity, while still allowing the bushings to work as intended.

Some SFC's and 1LE swaybars will also noticeably improve ride and handling with very little compromise.

IMO, there is no need to replace the factory TA unless you're having problems with it or your priorities change. Replacing the stock TA bushing might be a good idea though.


EDIT:

You can get the 1LE 32mm front and 21mm rear swaybars with bushings from SLP, most of our sponsors that sell SLP stuff, or as a kit from gmpartsdirect ( ref http://www.gmpartsdirect.com/results...ber=1LESTABKIT ).
The 1LE LCA is GM p/n 10164151 and should be available through dealers or gmpartsdirect among others.

TTopJohn

Thanks for the input - I realize this is not the typical request or goal for a Z28 suspension setup.

I see that there are gains to be had for cornering purposes with aftermarket LCAs and PHR and all that - but what I'm trying to do is make it handle as well as I can without compromising NVH.
I know that will limit me, but I don't need it to handle like a 2700 pound Mazda RX7, the goal is to make it handle like a 4000 pound BMW 540 - with the caveat that with a live axle it's always going to skip a few degrees to the side over a mid corner bump. Does that sound do-able?


Here's what I think I've picked up so far:
1) If I want to keep stock NVH levels, I need to keep the stock LCAs and PHR.
2)If I did aftermarket LCA and PHR with all rubber bushings, that would sort of defeat the purpose of the aftermarket parts - and not show much improvement over factory pieces with rubber bushings? Or would the deletion of the poly provide the perfect combo of stiff metal to locate the axle without any slop, but rubber bushings all around to absorb NVH?


The 1LE pieces sound interesting - I knew about the 1LE sway bars, but I did not know that there were 1LE specific PHR and LCAs - are the metal pieces themselves beefier, or is the only difference the stiffness of the bushings?

John95Z28

My suggestion about using a BMR control arm with all rubber (instead of rubber / poly combo) bushings should firm things up a bit without introducing any new noise or harshness, but it's just a -theory- since I haven't tried it myself. Like I said, you're more than welcome to try it, but I can't guarantee that it would be a noticeable gain compared to stock. From everything I've been reading on this forum I'm opposed to buying polyurethane bushings too, because of squeaks and (in LCA use) binding. I don't know why nobody out there makes aftermarket gear with rubber bushings; I guess they're all sold on using poly and rod ends.

As far as I know, 1LE panhards and LCAs use the same metal components, but with firmer rubber bushings. But I could be totally wrong about that, so don't quote me.

TTopJohn

Thanks John, I'll investigate further.

As far as brands of suspension parts, while I do have a BMR Strut Tower Brace, I think I'd prefer a more road racing oriented company for parts that actually bear a load and affect suspension geometry.
LG would be a more likely brand if I replace the LCAs - plus they are local so they could do the install.

Anyone else got an idea about what result I would get from aftermarket LCAs and Panhard Rod with all rubber bushings? Or know if the 1LE parts have stiffer metal or just stiffer bushings?

WayneSS01

I have also 'heard' the 1LE has the same metal components with the difference being in the bushings.

I have often wondered about just 'boxing' in the factory LCAs to increase rigidity.

This page has some interesting info http://www.geocities.com/motorcity/1701/index.htm

TTopJohn

Wayne, thanks for that link - there is a WEALTH of information there - and part numbers
1LE rubber bushings everywhere may be the way to go - that + Koni S/As front, Bilstien Revalves rear, and stock springs may be just what the doctor ordered.