bayer-z28

iTrader: (14)

I was told that the bump stops in the back of my car are causing most of my suspension problems. Yes, the Pro-Kit isn't the greatest, and the SLP Bilstiens aren't that good either.. Hind sight is 20/20.. But anyway..

Are there any ill effects of eliminating the bump stops in the back? I'm about an inch off of them when the car is just sitting and I was told that THAT would cause my car to be so loose. Can I just chop them? My buddy has the same shock and spring combo on his 02 SS, but his feels SOOO much more stable than mine. I was told that the SS's have a different bump stop in the back? THis car feels soo disconnected, it's pissin me off. I can almost feel the rear moving around. I have everything done to the SUSP except the rear sway, K member and A arms.

Riding on the bumps eliminates the susp system in the rear, making it rock hard. -True?

MeentSS02

iTrader: (11)

Riding the bump stops is definitely not desirable...I'm not sure on the size difference between the SS bump stops and yours, but they are definitely different (in color and shape). I ended up removing the aluminum plate that goes between the rubber and the body on mine to gain another 1/4-1/2" extra, but I still hit mine from time to time.

Although they aren't the best, I'd still venture a guess that riding those stops is still better than jamming the shock's piston all the way up in the body, killing your shocks. If you do anything, shave them down, but don't take them all the way off.

JD_AMG

Do NOT cut the bump stops, they are there so you don't bottom your suspension out. Your car feels disconnected because your shocks cannot damper your springs, it will feel floaty/bouncy.
What other suspension mods do you have?

bayer-z28

iTrader: (14)

I just copied this form my Fquick page. Hmm... Getting mixed reviews.. I'm not talking about chopping them WAAAAYYY down, just maybe cutting about 1/2" off. You see the shadow/ dark spot ont he bottom of the stop? That's how much I was thinking of cutting off.

Yeah.. I don't want to bottom the shox out either.. I read thru that stickey up top yesterday... It's conflicting w/ what I was told by someone else.

Strano 35mm Front Hollow sway, w/ Urethane Bushings
Hotchkis Lower Control Arms w/ Polyurethane Bushings
BMR Chromemoly Adjustable Torque Arm W/ Poly Bushing
BMR Chromemoly Shock Tower Bar
BMR Chromemoly Tubular Subframe connectors
BMR Chromemoly Adjustable Panhard Bar
BMR LCA Relocation Brackets
Eibach Pro Kit Springs
Bilstien Shocks
Energy Suspension Trans Mount

Krab

iTrader: (28)

Take them off and sell them to me!

mitchntx

iTrader: (14)

I'm the conflict.

If he's on the stops, he IS bottoming the suspension out, sending the spring rate infinite. What happens when a car's rear rate is increased? It gets loose ... <gasp><argh>

1 inch of rear travel on the rear suspension isn't enough. A cooler with a 12 pack in the rear well will set Eibach Pros down more than an inch. A 0.8G turn will certainly compress the inch he has.

Some of you geniuses need to do some actual measurements before you begin typing. The spring will coil bind WAY before the shock bottoms out and the rear diff tube will hit the frame rail before the spring coil binds. There is no downside.

It's a simple test, actually ... yank the rear springs and jack the diff up. Does it stop on shock travel or against the frame rail first?

Yank the bump stops, put a tie wrap on the shock tube close to the shock body and a dab of grease on the diff tube where the bump stop was. Drive it, trying to take turns hard, rolling the car over, over speed bumps, etc. Now look at how far up the shock tube the tie wrap has moved. Lemme guess ... you will have about an inch of shock travel remaining ... and the grease has magically transferred from the diff tube to the frame rail. <gasp><argh>

I have no bump stops (haven't had for years) and running an 11" rear spring with Koni SAs on the rear. No issues what so ever. An 11" rear spring with isolator equates to about a 1" rear drop in your simple terms.

Bayer .. we discussed the lemmings on this site. Believe what you will.

Get a decent set of rear springs ... $100 investment is all it would take. Not knowing what your car's weight is, I would think 150# or 175# at the most
http://www.pitstopusa.com/SearchResu...ategoryID=4561

02TransAm/Batmobile

iTrader: (32)

Yea, just get a stiffer spring for the back.

GETGONE

iTrader: (5)

If you cut that in half it will be about the same height as the SS cars have with the 17" wheels. SS and WS6 got an aluminum spacer and about 1.5" rubber bump stop that's pretty flat and not as pointed as your stocker is. I wouldn't remove it completely so it saves from smacking the axle on the rear frame rails. I've been into lowered trucks for years and when lowered that's how you gain clearance and keep your bumpstop buy whacking it in half.

JD_AMG

So without the bump stops the axle will directly hit the chassis? And that is "safe"? Why did GM put the bump stop on in the first place?

z28bryan

iTrader: (7)

How does that measure the travel left between the bottom of the shaft and the bottom of the shock though?

The question is, will the shock shaft bottom out on the bottom of the shock before the chassis hits the axle or the spring coil binds?

mitchntx

iTrader: (14)

It's 2" more suspension travel. If your suspension is that soft, then you have bigger problems. Again, I have no bump stops and I NEVER hit the frame rail.

But I do have an adequate spring rate to keep the car under control.

I will grant this ... banging against the bump stops will definitely get the car to rotate. But you better have your collective **** together to catch it.

Bump stops were installed with

1) stock ride height in mind
2) to quieten any inadvertent impact the diff tube would have


If the tie wrap is at the top of the shock shaft, you've bottomed out the shock. Anywhere less than at the top, you haven't.

z28bryan

iTrader: (7)

That's interesting stuff. Too bad there aren't more people to discuss their experiences with suspension.

I agree that there's a lot of recommendations and opinions without really digging deep into why and how, and I think that's what a lot of people want to know.

mitchntx

iTrader: (14)

Don't take my word for it, do the test.

Any one posting in this thread, or even this forum, including me, could be an absolute douche bag and lead folks down a misguided path. It's happened on the internet before and this place is not immune.

I'm no expert. Have never claimed to be nor have I touted my multiple wins/championships in a given race group as proof. I do advocate NOT taking someone's word on something without a thorough investigation.

It's easy to throw a lot of $$$ at something and get a "different" feeling in the SOTP. But, in the end, (no pun intended) "different" does not equal "better".

MeentSS02

iTrader: (11)

Interesting...I was always under the impression that the bump stops were necessary. I think you can consider these things GONE in the near future. I hate hitting those damned things.

Sam Strano

iTrader: (41)

Let's jump to conclusions...... Wait, lets don't.

Here's what we know:

--You have shocks not intended for the type of springs you have. Shocks are dampers, and insufficient dampers cause a lack of stability.

--You have boxed and bushed LCA's which are a binding mess, and binding makes the car jumpy and twitchy in the back.

--You have LCA brackets, and I might hazard a guess that you are running them in a lowered hole. Trouble is often that puts the arm tail down, the more tail down, the more roll oversteer you get. Maybe yours aren't, but I run mine tail up in my car for stability, and prefer that over level.

Seems to me you have three pretty obvious things staring you right in the face.

Bumpstops are NOT BAD THINGS. They are only bad when you do not understand them. The ones on this car are nice and progressive, better in fact than the SS units. And when they work, they add wheel rate, just like stiffer springs. But they don't return as much energy as springs do. Now, between your shocks and your springs, you are likely hitting the stops too hard and too fast, but that's NOT THE BUMPSTOPS fault. And taking them off is frankly stupid.

You have a lot of mis-matched parts. The bumpstops are the the mis-matched items. And taking them off doesn't cure anything.

Fix the issues, don't band-aid them. BTW, these are not actually bumpstops on this car, they are more accurately bump rubbers as they are progressive and have movement. Bump rubbers or packers are used on race cars all the time. They must be horrible.

Sam Strano

iTrader: (41)

I COMPLETELY agree with Mitch on one point. You shouldn't take someone's word for absolute gospel because any moron with a keyboard can tell you anything. Which is exactly why I explain how things work to people, just as I did in my prior post.

So you can decide how to procede based on relevant information.

Greggy

Ooooop, here we go.

Hey, I thought Trackbird smashed his rear koni's by removing the stock yellow bumpstops and replacing them with koni ''on shock' type that were not sufficient. Wouldn't that be the same as no bump stops?

By the way, the front bumpstops are VERY important. I killed two new koni's up front before adding two extra white nylon packers washers per shock. This made the koni factory bumpstops hit 1/4" sooner. No problem since (fingers crossed) and the ride is not much if any any worse. Sam cued me in on the idea and Koni gave me four packers in the advanced replacement part box they sent me. Thanks to both.

Back to the rear bumpstop issue:

w/ 550/150# springs, 1" clearance off rear axle, Moog 1LE bushed stock LCA's, Koni sa shocks, 35 hollow/21mm solid bars, good 245/16" tires (32/29psi), and the progressive yellow GM bumpstops, I don't have a loose condition at all. In fact with a my mild performace alignment, it's actually a bit tight. I would think a bit more neg. camber would balance it out.

Plus with that soft Pro-kit rear spring, I'm sure you will hit the frame hard in the back w/o the bumpstop. I hit my bumpstops hard without issue all the time... Just a little jolt in the seat of the pants and the chassis settles out nicely.

Ironhead

Better yet, replace them with the progressive Z28 stops.

An SS owner friend of mine was skeptical of this until he actually tried 'em.

z28bryan

iTrader: (7)

Putting the "Should I remove my bumpstops?" issue aside, your prokit springs seem pretty low and I didn't think prokit springs only allowed like a CM of suspension travel.

What is your goal Bayer? If you are going for a low looking car and dont care about ride quality then you have no problems. If you are going for good handling either get rid of those prokit springs and get good shocks on there like some konis or go down Mitch's road where you remove the stops and make sure you have a good spring

I still have questions about removing the stops though. Mitch says you'd bottom out on the frame or coil bind before you bottom out the shock. Greggy says people have bottomed out their front shocks when removing the bumpstops on the front. What is the deal with the rear bumpstops? Someone has either bottomed out their shock with rear bumpstops removed or they havent. Which is it?

I am under the impression that bumpstops also clearly define your endpoint of wanted suspension travel and that the stock points are sufficient enough. The rear seems to give me what I need as far as suspension travel is concerned. I don't know if I'd want to venture down the road of allowing more rear movement so low down where I'd have to start worrying about my tires bottoming out in the fender.

EDIT: I just noticed Greggy mentioning that Trackbird had bottomed out his rear shocks by removing the stock stops and even added the on-shock bumpstops. I'm gonna have to go with the majority then on this one then. Someone has removed their stock bumpstops and has bottomed out on their shock. That's all I need to know...

Sam Strano

iTrader: (41)

Kevin Glaser aka Trackbird broke his rear shocks w/o bumpstops with much stiffer and less low rear springs (H&R's at about 200 working rate, which wasn't stiff enough). I was the one who found 'em, he didn't even know and wasn't convinced until he had them dyno'ed... they were good and blown up.