Studytime

iTrader: (15)

I'm getting really tired of my '98 when going over bumps. The rear of the car seems to jump to the side when crossing expansion joints or asphalt patches in the road.

I'm at 107K miles on the stock DeCarbon shocks, and my only suspension modfications are boxed-in factory lower control arms.

Part of me wants to buy a fancy adjustable panhard ride and "fix" my problem, but I'm not even convinced this would be a genuine solution.

Please assist me on what to check for as this is really starting to aggravate me.

My car DOES NOT have SFCs either, but they are going on soon.

Ben T.

VIP1

A live axle will always jump over bumps especially in mid-corner. You can reduce it with the following:
* New Shocks (ex: Bilstein HD, Bilsteing HD revavled by Sam Strano, Koni)
* Poly/Rod or Rod/Rod LCA and PHR (I'd recommend Poly/Rod)

The new shocks will be a big improvement in ride and control over the stockers with 107K mi on them. The rod ends will transmit more road noise into the cabin, but to some the improved control is worth it. If you dont want rod-ends, go with 1LE LCA and PHR. If you are into only drag racing the boxed LCAs and PHR are fine, but if handling is your game then Rod ends are the ticket (just be sure to get good quality ones with teflon linings, they are a wear item also).

Studytime

iTrader: (15)

Thanks VIP,

I'm looking into a set of Bilstein HD's for the rear of my car. It's a daily driver that sees track action about once a month. It's important that it launches well, but even more important that it rides will back-and-forth to work/school. I plan to use these shocks with my existing rear coil springs as they *appear* to not be sagging any.

Please advise on this combination.

Think I'm going to try and borrow a friend's PHB and try it for ride quality improvements.

Thanks.

Jon B.

iTrader: (5)

I thought the same thing before I put on my LCA's and PHB. Made the rear end a whole new animal. I'd get Poly/Rod LCA's and a Rod/Rod PHB. Dual rod ends on the PHB are the way to go IMO and they dont transmit much noise (if any) into the interior.

Jon

Studytime

iTrader: (15)

I'm up for suggestions if you like the piece on your car. I'm going to research it, but someplace to start would be nice.

I NEVER plan to lower my car so adjustability is not a concern.

THANKS A TON GUYS!

Ben T.

BLOODTA

iTrader: (19)

Sorry to Hijack, but I've got new Bilsteins revalves and Hotchkis springs plus a dual adj. PHB and TT2's 9.5 front and 11's in rear. My rear-end jumps more now than it did when it was stock. What's the deal?

Studytime

iTrader: (15)

I'm really considering a pair of the Aluminum LCAs that are for sale at hotpart.com. I'd like an opinion on these. Let me know guys.

Ben T.

trackbird

iTrader: (4)

If they are the ones I think they are that use the 1" or smaller diameter tubing (and small rod ends on some of them), run away, far away, from them.

A PHB is not your problem. It's shocks, shocks, shocks......

UsaTraveler

Mine used to do that real bad to. I thought it would be worse once I lowered it, but to my surprise it sticks like glue now. I can say specifically which part fixed it, but I would agree with the other posts here.

Studytime

iTrader: (15)

Glad to know about the aluminum LCAs. Thanks for the warning. I'm still learning about suspension parts. I'm guessing that they will deflect at the line (?).

Trackbird, I'm really confused here. I've been reading that Sam says the Bilsteins are the best off-the-shelf shock there is, but four posts up "BloodTA" says he still experiences this same problem I am describing.

I'm just trying to learn what's going on here. Help me out guys.

Ben T.

trackbird

iTrader: (4)

Ben,

I don't think Sam has ever said exactly that. He usually describes the Bilstiens as "better than decarbons", but not exactly the right answer. However, they build a good shock and with the right valving in it, it can be a useful shock for performance applications. So, I think you've heard Sam say that they are a good shock for our uses when modified/revlaved or a mild upgrade on a stock car that's not lowered. At least that's my interpretation of Sam's position on them (and we've discussed it a bit).

Aluminum suspension components can work very well, but if they are too thin, you run an increased risk of failure. Also, if they are "knurled" (as some of the "cheap" ones are that I've seen), run far away. The cut lines that you mill into the aluminum to make the knurled portion are great places for cracks to form. Try this experiement (if you have a scrap of aluminum sheet). Take a section of aluminum sheet, then bend it with pliers. It should bend. Then, take a knife and "scratch it" (run a knife or an awl down the side of a ruler) and bend in on the scratch with pliers. 99% of the time, the aluminum will crack/break right on that line. Aluminum doesn't like sharp edges and knurling it is a bad idea.

Those wheels BloodTA is running are very, very heavy. If there is not enough compression damping to control them, you'll still get the "hop".

BloodTA, if you have stock wheels or can get a set of stock 16" (or even 17's if it's all you can borrow for a few minutes) wheels from a friend. Try putting them on and driving your car. Tell me if it still does it (or if it's still as bad) with the lighter wheels on the car.

Studytime

iTrader: (15)

Trakbird, thanks a lot for the help thus far!

Here's where I was quoting Sam from;

https://ls1tech.com/forums/showthrea...&highlight=kyb

Will respond with more later.
Ben T.

trackbird

iTrader: (4)

Ahh, ok then.....

He also said "they can use more force". And, it appears that they can use it. They are better than most others though, so it's all a trade off.

BLOODTA

iTrader: (19)

I don't think I can do that but I have heard the 315's in the rear grab a little more and that can cause the rear to jump in and out.

VIP1

Bilstein HDs are a better match for the stock springs than the stock DeCarbons. I installed them on my car and noticed an improvement. Check out my sig to see what else I have. Mind you, although I have improved control, I also have more noise (rod ends).

Just becuase you arent lowering the car doesnt mean you dont need adjustable components. My rear was slightly off with the stock stuff. (BTW, I had to convince the alignment guy to do a 4-wheel alignment instead of the typical 2-wheel alignment. He didnt beleive me at first that I installed adjustable components in the rear.)

junior28570

iTrader: (22)

A little data for the cause;

I just swapped out my Sumi' 315's for some 315 BFG DR's .. I got the skip/"side step" y'all talking about now. Never had it (or noticed it anyway) with the Sumi's.

I'm gonna' try lowering the pressure in the rear tires a bit to see if that helps. By my tread wear pattern (observed while rolling on dusty/dirty road), I'm thinking I'm running a little too much air press. anyway.

(All stock suspension)

Junior

Dean95z28

iTrader: (7)

Well, just some food for thought if you drive your car hard, noticed this problem on a buddys car, The driver side spring perch had broken welds letting the rear end do some funny things, it wasn't broken all the way off just on the sides of the perch. never noticed the break until we removed the rear. just something you might want to check out.

ChocoTaco369

lol don't you love it when you have to hit the brakes going over bumps and sewer gratings and the car pulls to the left or right? i love that feeling i still like my live axel though. it's great for a straight line

HPP

In reference to the thought that a live axle will always do that - my '88 GTA (hard top) never did it. I'm sure if it was a big bump it might have, but I drove that car hard on crappy back roads, and often, and I just don't remember it being a problem.

My 02 WS6 on the other hand, is terrible in that regard. Even over fairly decent surfaces it tries to jump. Other times it sways back and forth (like a wobble).

This just reinforces (in my mind) the experience of the racers (like Trackbird, Mitch, Sam, Cal, etc) when they say that it's all about shocks.

While my GTA had Bilsteins from the factory, perhaps Bilstein just doesn't have it quite as sorted out with the 4th Gens. The koni's would certianly be better (from what I've read) and would probably help to solve a lot of that problem.

Also, I found that due to the heat, I had too much pressure in my tires. (about 46psi all round) When I aired them all down to 40, the ride not only got much more comfortable, it calmed down and felt a *lot* more planted in corners - less sway/wobble, less jumpiness, etc. (which even further convinces me that shocks (aka - damping) are the key)

Studytime

iTrader: (15)

I'm developing a new theory here guys. I'm starting to wonder if my problem (and possibly other's) is simply bumpsteer? I have a new-to-me rack and pinion on my car and a fresh alignment, but I've been noticing some play in my wheel lately. Last weekend I had my car supported by the frame rails and I could move the front steering assembly by hand (tires would turn left/right) with the steering locked. There wasn't much play, but if I understand correctly any play is too much play.

Perhaps this is my problem and the solution to other's problems? Could it be that the bumpsteer phenomenon is more apparent as weight is transfered across the "frame" of our cars and loads unloads the front suspension? This would explain why the back of our cars seem to jump to the side.

The rack I installed on my car looked like it was in nice shape aestetically, but it may have had a lot more milage than was disclosed to me. I bought a low mileage used rack because the new GM racks are $380 plus whatever rediculous freight charge GMPD.com is going to way. Also, it says there is a $150 core. So, I'm sure initial out of pocket could approach $700 after it's all said and done with a new alignment, and that's doing the install yourself. So, I bought a used rack and installed it myself with a new alignment from Tire Kingdom.

Before I tear into the rack and pinion to prove/disprove this theory, what other wear items up front could need service? I didn't see an idler arm or pitman arm . Is it just the rack? My car doesn't pop when turning to indicate it's the balljoints, but perhaps it is them?

Ben T.