LS1nut377

iTrader: (16)

me and my friend were talking about it and were wondering if it is true that they make shocks made for lowered cars. my car is lowered 2 in with eibachs and it rides pretty stiff. just wondering if mabe getting some good new shock would help that out? open to ideas if anybody has any

99Bluz28

iTrader: (35)

With the eibach sportline lowering springs the ride is really stiff because your riding on the bump stops;that's problem#1.
Then, on top of that the sportsline springs are actually no stiffer than the factory 1LE springs; problem#2.
So, with basically no suspension travel (except what the bumpstops provide) your ride quality will remain about the same regardless of the shocks used.

So if you want a softer riding car you need suspension travel, and good shocks.
Solution#1: New shocks, new springs.$$$$
Solution#2: New shocks, new springs, and "Upper Mount Mod" for the front, and cut 1" off the rear bumpstops.$$$$
Solution#3: New shocks, and "Upper Mount Mod" for the front, and cut 1" off the rear bumpstops.$$
Solution#4: "Upper Mount Mod" for the front, and cut 1" off the rear bumpstops. FREE

LS1nut377

iTrader: (16)

aahhh haa thank you

99Bluz28

iTrader: (35)

If you're looking to spend as little as possible, solution #4 will make for a noticeable improvement in ride quality.

Been there, done that!

LS1nut377

iTrader: (16)

yes i do need some ride improvement thanks again

Sam Strano

iTrader: (41)

All the cutting and trimming in the world doesn't really help that much. You still have springs that are too soft and too low to work as they should, and dampers that can't control the springs in the much smaller amount of travel.

While I think the front mod is ok to do, I don't agree with cutting the rear bumpstop. Yes, you gain travel, you also make the bumpstop stiffer when you do get onto it. Ever here the saying it's not the fall that kills you, it's the sudden stop? Basically you gain travel, but the contact with the bumpstop becomes more sudden and that's where a lot of the complaints stem from in the first place--the abrupt change in suspension rate.

The issue is you have springs that are about looks, and looks alone. The shocks were intended for (and even then didn't do the best job of controlling the) taller softer stock springs. Basically you have two hugely important suspension parts that in themselves aren't that good and together are worse. Trying band-aids might help in small ways here and there, but every action has a reaction.

I Go To Costco

iTrader: (1)

So its okay to cut the front bumpstop? Will that make the ride harsher or softer (I have your springs + Koni 4/4) also its NOT recommended to mount the Konis on the lower perch, right? Thanks...

Sam Strano

iTrader: (41)

The stock front stops are very short, and very hard. Cutting them won't do you any good. Koni stops are very long and soft and I definitely do not recommend cutting them because they aren't super hard and doing so really risks damage to the shock because you are taking away it's best form of internal protection. If you do, and break one, it won't be warrantied.

And if you have lowering springs, the Koni's need to be in the upper perch position.

Formula51

But clearly the bump stops were designed by GM engineers for a stock ride height car. As such, there is about 2" of travel between the axle and bump stop.

On a lowered car, that travel is greatly reduced to as little as 1/2". I fully understand the important function of the progressive bump stops but it definitely seams as if they should be altered for a lowered car.

Simply cutting them shorter is not the solution for the reason you explained above. However, what about cutting them shorter and re-tapering them to match the stock shape such that the progressive nature of the bump stop is unchanged? Essentially all you have done now is re-designed them to allow more adequate travel on a lowered car.

I'm not talking about cutting off enough to potentially damage the shocks, but enough to allow some adequate suspension travel. Certainly the GM engineers would not have used these same bump stops on a lowered car. I know I wouldn't have.

Thoughts?

z28bryan

iTrader: (7)

Stock springs start higher and have more suspension travel.. less springrate. Aftermarket springs start lower and have less suspension travel.. higher springrate.

My thoughts... if you use the appropriate shock valving with a good lowering spring, then all this talk about modified bumpstops should be an afterthought. The spring rate will be more gradual as you enter the triangular bumpstop and won't spike to infinity like it would if you had more suspension travel and a blunt shaped bumpstop. Some people don't mind running Sportline springs with stock shocks, but for those who tried this combo and don't like the ride quality should really consider what a lot of us have been recommending to everyone all this time.

Sam Strano

iTrader: (41)

Cutting them and them retapering them will cost you bumpstop rate. Given the choice between long and soft and hard and short, or in this scenerio short and soft (which won't adequately slow the mass on certain impacts), I'll take the longer, softer, progressive stop every time.

If you ask anyone running full sized progressive stops with *GOOD* springs and dampers, they don't have any issue with "bottoming out". Yes they get on the stops, but it's not the slam-bam smacks you get with square stops, or lousy dampers, or not enough spring rate to compliment the stop, etc.

I've won all my titles on cars with stock rear bumpstops, GM and Ford, stock and lowered. And any time the car would do something abrupt, a change in damping would calm it right down. And fwiw, the car I'm currently racing (solid axle, RWD pony-car....) basically sits on the rear stops statically, and it's very quick and has become the car to have in the class.

Formula51

How so?

By reshaping the bump stops to match stock, removing 1/2" from the bottom would be equivalent to removing 1/2" from the top where the stop bolts to the car. As long as you are not compressing the bump stops in the region where they bolt to the car (atleast not significantly), this would not effect the bump stop rate. I believe this to be the case in all but hitting the most severe pot holes or dips in the road.

Therefore, the ONLY thing you would do is gain 1/2" of travel. As long as that does not bottom out the shock, I can't possibly see how that is a bad thing. In fact, I am surprised EVERY lowered car doesn't do it.

The GM bump stops were not designed for a car with a 1-2" lower ride height. So the compromise is leaving them stock. Re-shaping them should be the norm from what I can see.

Sam, I say you and I both try it. I have a rather abrupt side-step type of loose condition in certain high speed turns. I know exactly where, and at what speed it occurs on this certain turn. I would be curious to see if trimming 1/2" off and re-shaping fixes the problem. It would be interesting to see what you thought after driving on a set of trimmed and reshaped stops. You could even do some back to back runs comparing stock to trimmed as it is an easy change. Will your class allow you to trim them?

z28bryan

iTrader: (7)

Like I mentioned above.... I'm satisfied with the ride quality because of the combo of koni/stranos and stock bumpstops. The reason why others want to cut bumpstops is because they aren't satisfied with their ride quality. Not saying you should or shouldn't do anything here, but I'm just explaining why I (lowered car) don't need to modify my bumpstops.

99Bluz28

iTrader: (35)

I've never had a problem whith my factory bumpstops cut down 1" shorter, but I also have air bags (springs) on the rear of my car and rarely hit the bumpstops with much impact at all. IMO, air bags in the rear is the best way to go for a decent ride quality with a really low ride height.

Formula51

I'm not even thinking about ride quality. If you are getting into the bump stops hard enough that they increase spring rate significantly, it can cause problems such as a loose condition.

Essentially, the bump stops are never giving your springs room to work. In some corners, you never/barely contact the bump stops, but in other corners you contact them hard. Therefore, you are driving a car that behaves like it has different springs in the rear depending on the corner and how much you are depressing the bump stops (they are progressive rate). This now makes a set of liner rate springs progressive and a set of progressive rate springs doubly progressive. Come to think of it, it might actually compound the ramp up rate of progressive springs. Hmmm, perhaps that is what I am experiencing with my Hypercoils and bump stops.....

A Camaro with stock ride height has 2" of clearance between the bump stop and axle. In other words, the bump stops were designed as a cushion for hard impact, like potholes, and a prevention of damage or tire to wheel well contact. With 2" of clearance you will not be contacting the bump stops the way a lowered car does (even with the soft springs).

With a lowered car we are all riding around contacting the bump stops constantly and acting like it is normal. I hear phrases like, "that is what they were designed for". No, they clearly were not designed for a lowered car where the distance from bump stop to axle is only 1/2".

There has got to be a better solution. I think trimming and re-shaping makes sense, but I am certainly open to some other ideas.

If shock damage is avoided, can anyone think of a reason why trimming AND re-shaping the bump stops would not be a good idea?

Formula51

Expanding on the spring rate idea.

Factory rear bump stop from here:https://ls1tech.com/forums/suspensio...ml#post2109836

Next is the factory rear which is 2 5/8" tall
1/8 45
1/4 65
3/8 95
1/2 125
5/8 150
3/4 200
7/8 260

If we look at a progressive spring, take my Hypercoils as an example, spring rate goes from 165-220.

I don't have actual data, but for arguments sake, lets say the spring rate changes as below:

1/4 165
1/2 185
3/4 200
1 210
1 1/4 220

With half an inch of clearance to the bump stops you may get a situation that looks more like this:

1/4 165
1/2 185+45=230
3/4 200+65=265
1 210+125=335
1 1/4 220+260=480

Essentially, you have an entirely different set of springs back there when contacting the bump stops so early. Springs that ramp up very quickly, and very high.

With a linear rate spring of say 150, you would now have a progressive rate spring that looked something like this:

1/4 150
1/2 195
3/4 215
1 275
1 1/4 410

Still ramps up pretty quickly, but the problem is not nearly as bad as the compounded nature of a progressive spring. Perhaps this is why some, like Sam, prefer a linear spring in the rear when running stock bump stops.

Just thinking and learning. Thoughts welcome.

99Bluz28

iTrader: (35)

You could always use some Koni or similar 55mm shaft mount bump stops, mounted on the shock shaft with a bump stop cup or large thick washer right above it.

Like what JasomWW did in the pictures below.

On my car, I measured out how much travel I had and then fitted the best bumpstop I had onto my shock body. I'm running the Koni SA rear shocks and this is what I came up with on my car.


Once I lowered the rear to about 26 1/4" or 26 1/2" (I can't remember right now) there is was only about 1/2" between the bumpstop and the shock body, but that's OK. I'm running a stock spring modded for 170lb linear rate and have the Koni shocks adjusted where I want them. Even though the Koni 55mm bumpstop gets used all the time, it's so smooth and progressive I really can't feel it. The rearend just soaks up the bumps with ease and that's the main goal.[/QUOTE]

Sam Strano

iTrader: (41)

I don't need to try it. I don't have the issue you have, and by in large that comes from having a proper combination of spring rate relative to ride height, and damping that controls the speed at which you get onto and rebound back from the bumpstop.

I ask: What is your setup? What shocks? What springs? As for the bumpstops not being made for a car lowered, they don't need to be. That's what the spring design and damping rate compensates for. In the end the bumpstops only come in at the end, the issue if you slam onto the them too hard, or too fast... That's not their fault. And fwiw, I have none *NONE* of those issues running full length bumpstops on my own car which is worked much harder suspension wise than most.

Formula51

Sam, you may be able to avoid any problems with the bump stops by having good combination as mentioned above, but that does not mean the bump stops are properly sized for the car.


I have Hypercoils with Bilsteins (put on by previous owner). I will benefit HUGELY from Koni's and will be ordering them from you in the future. I am running a 32mm front bar with a stock 19mm rear bar and a LG Motorsports Torque arm and poly/rod end adjustable panhard bar. Stock LCA's.

My bump stop problem may be able to be AVOIDED with Koni's. However, even with a stiff progressive rear spring like the Hypercoils I will likely still contact the rear bump stops significantly due to the lack of clearance and this could cause my EFFECTIVE spring rate to become high enough that this loose condition still exists. If I could bye another 1/2" of travel and keep the same bump stop spring rate by reshaping, I think it would be more ideal.

Couldn't have said it better myself. What if the bump stops didn't have to be compensated for but could be the integral part of the suspension they were intended to be? This is what I am after in my head, just trying to figure out how to make it reality!

With only 1/2" clearance between my axle and bump stops, they come in a lot sooner than "the end". I have a mirror finish on my axles from the bump stops polishing them! As I said, I have only noticed this phenomenon on high speed, high lateral acceleration corners. Particularly those with a decreasing radius. I'm talking 65-70+mph turns, which definitely makes your butt pucker when the rear does a little side step, haha.

I'm hoping Koni's fix all my troubles, but I'm not totally convinced. Even if they do fix it, could they function better with trimmed/re-shaped bump stops......that's the always questioning engineer in me I guess.

Always appreciate your input Sam.

JamRWS6

The bump stops are used to stop the suspension travel and keep you from grenading the shock. Why do you want to make this an integral part? If anything they are safety stops; otherwise a proper springrate and damper should be used that control suspension motion before slamming into a bumpstop.

Seems like shocks and better springrates is what you need rather than trying to make bumpstops compensate for the lack of being able to dampen the springs.