Without ZQ8 bump stops your suspension will periodically crash into the frame regardless of other bump stops used, or trimmed. I'm not sure why you're so hostile to them. Why do you think so many of us (including myself) use, and recommend them? As you can see, the bump stop actually contacts the spring pocket of the frame horn. There is no way to lower the car's front without reducing the distance between control arms, and the frame.

 

Thank you for the pic 1slow96, just posting mines here as reference for the future

 

Without measuring where the bumpstop is, guessing more like 1.5-2 as it's further out than the centerline of the spring if picturing it right

 

Or, stick a measuring rod through the bump stop mounting hole in the control arm.
(Probably most accurate)

 

You could jack the front end up from the cross member, and the release the jack quick, and maybe find a way to monitor it. Maybe aluminum foil crunched up?

This is after a few beers so take it with a grain of salt.

 

Gopro would probably be the way but I think I have the info I need for now. Not actioning on anything yet.

 

just copy pasting a response from rustic racing 20 years ago for future reference.

The "feel" and "performance" of your front suspension is determined by your springs, shocks and sway bar. If your frame is resting on your bumpstops you are adding another component... which is the "spring rate" of the bump stop.... and removing much of the effects of the other 3 components.

If you have gone out and spent several hundreds of dollars on you springs, shocks and bars... why would you want your suspension resting on $15 worth of foam?

If you want your suspension to work the way it was designed, your bump stop should be just that... a BUMP STOP. It's only there to prevent metal to metal contact during severe suspension travel.

So, I recommend at least triming what ever stop you use so that you have some room for suspension travel before it's contacted. This is why I sell the "button" style stop that is very low profile. It allows your suspension to do it's job and it only interferes when it has to.

Just one man's opinion.

I'll start by saying that there's no accounting for taste... what one guy thinks feels good another may consider harsh. And the bottom line is that if you like the way your car feels and handles... then you have done what's right!!! Because that's what it's all about... finding what you like and building your car to match.

Now... why do you think the ZQ8's made your car "feel better"? My guess is that when you lowered it it was sitting on (or very close to) the factory bump stops. The factory stops are not very forgiving, especially when they get old. So when you hit a little bump the stops slammed into your frame... and that felt harsh.

A low profile stop may feel just as good because it allows your springs and shocks to absorb that little bump without the bump stop being involved.

From a performance stand point this is a much better option because you have a more predictable "spring rate" through a longer length of travel for the suspension.

I'm not trying to talk down the ZQ8... it's a good part. I'm just trying to explain a little better what's happening... and give options.

 

Personally I'd go with the shortest stops I could and good set of adjustable shocks. I agree with the idea that the springs/shocks should be doing as much work as possible to stop the compression in a controlled manner, and the shortest stops give you the greatest range to do it in.

-Brian

 

I looked at this thread and thought deja vu.

It seems to rehash several old toonwarrior threads.

From this thread:

How important is the cone shape of the z28 bump stop?

Essentially my car is lowered to the point where I had to grind almost an inch off the z28 bump stop for it not to make contact. You can see in the image below how close the stock one is to the frame. My first attempt at trimming down half an inch, but as you can see it was still too large...

www.impalassforum.com

I think in another thread the canuc springs were considered to not have enough travel.

So if the canuc spring height was measured you know what drop is too much.

How close is the canuc height to the 5662 height?

From your current picture:


From some less than scientific calculations and what looks like missing grease plus:

I can see atleast 2-3 inches of drop right at the center of the wheel well.

I think you are already hitting the bump stops. IE: the grease and dirt are missing.

The more time on the bump stops the less the suspension is doing it's job

 

The missing grease is from when I was on the lowering springs hah.

My car with the stock height #750 springs do not hit the bumpstops at all. Not any incidents I can recall of atleast

Which led me to the question I probably have some space to drop it while still maintaining full travel.

The 5662 makes it easy to figure out since it's exactly a 1.4inch drop at the wheel well. And .7inch shorter at the spring.

The Canuck springs had like a spring rate of 480 which is wayy too low for how it drops the car. I went from Canuck to Hotchkis and honestly ran into the same issue. Then I made the switch to the 750 and I've been really happy with them. But hey if I can lower the CoG a bit without screwing up the ride quality of the car I will


As of now I am not touching anything. Just needed this thread in the future when I revisit it

 

My car with the stock height #750 springs do not hit the bumpstops at all. Not any incidents I can recall of atleast

Gopro would probably be the way

Put some new grease (you need some color not black) on the bump stop. Clean the contact point.
Run a race.
If the grease is on the steel you are making contact.

You could take out the springs then measure the distance from ride height to bump stop drop.

What seems to be forgotten is the Impala ride height is a afterthought.
It is a inch or more lower than the design height of other B bodies.

The question is when you go into a turn and produce a 1G side load will a suspension with 750Lb springs and 2.4 inch lower than stock b body ride height hit the bump stops? And how hard?

 

If you want more suspension travel, use drop spindles. The conditions are that you must use 17 inch rims and add 12 mm wheel offset (18mm total) to compensate for the track increase of the spindles.

 

"Does anyone know if Global West has ever considered making a full set of lowering springs? I know there front springs may lower .5", but have they ever mentioned a full set that would lower an SS 1-1.25". Also, if the front suspension camber gains were fixed to be optimal, could it be possible to see 1.xx g's on the skid pad? "

Ed Runion's reply:

No they haven't, for a good reason. And this gets into why my car isn't lowered much either.

Namely, the suspension has a "sweet spot" geometry-wise where it works best. And, not surprisingly, it is pretty close to stock SS height.

BTW, the GW front springs basically don't lower an SS at all.

I don't think you'd see much cornering gain (maybe a little, but not lots) with the modified control arms versus a stock parts alignment that is "handling oriented". The real gain (IMHO) of the modified parts is that you'd be able to get the better handling WITHOUT having to run an alignment that is detrimental to tire life to do so (i.e. case on my car right now : handles great, but I'm not setting any tire life records)


"LOL, yup Ed's setup is Top Secret, "Eyes Only."

Off the top of my head;
T56
F-Body front bar/slightly stiffer than stock rear bar(seriously)
GW front springs/stock rears
GW rear lower arms with DelAlums/aftermarket uppers(rubber bushings?)
GW DelAlum FCA bushings
HAL QA1 shocks
"Sport tuned" alignment
Torsen T2R "

Ed Runion's reply:
"Only thing that Wayne missed on my setup (and it DOES make a big difference) is that I am running 275/40R17s on 17x9.5" in front and 315/35R17 on 17x11" in back. Even just going to 17x9.5" all around with the same exact tire as on a 17x8.5" rim (i.e. same 275/40R17 on either rim) will help a good bit."

Lateral acceleration

Anyone know the lateral acceleration(g's) of the stock suspension on our cars? Also any specs for the skid pad of a modified suspension?

www.impalassforum.com

And this gets into why my car isn't lowered much either.

So, lowering is probably not on my list

Navy Lifer:
"So, lowering is probably not on my list--if you were building from scratch, that could be factored in, but the suspension points, wheel travel, suspension geometry, wheel openings, etc limit how far you can or should go in the lowering department--just for the sake of making the car lower. Yes it looks cool, but first & foremost, there MUST be adequate travel for the suspension to work properly. Lowering puts the front suspension, especially, in a situation where the geometry is at it's outside range of acceptability (or beyond) and IF the outside front position bottoms out, the available traction at that corner basically goes to zero.

Better to up the rate on the front springs to ensure travel at high loads, keep close to standard ride height (for all the reasons mentioned above), play with the different bars you have mentioned, and then work on an ideal alignment setup to dial in the car.

Do not assume that a rear bar is essential for the car to handle well--increased front spring rate will help reduce camber change from chassis roll (which drastically changes total tire contact patch). Some additional front spring suggestions include Moog 7268 (750#) and 7270 (800# +)--ideal to work with this would be a re-valved AK1053, or the street adjustable Koni's, but, again, there are the budget/rules consideration(s).

Stock SS rear springs are a good starting point--OE spec is 154#, I recall. The Speedway springs may actually lower the rear, but that can be corrected with spacers, or perhaps accommodated in the acceptable range from stock ride height springs--just remember that lowering the rear will also have an impact on what the front alignment settings are.

For the money spent, good shocks are one thing to focus on, but not understanding the full budget limitations, I can only say do the best you can. The other consideration with lowering the car is that shock length relative to total suspension travel does matter--and ideally the shocks will be at mid-travel with the car static. Lowering the car any significant amount creates some potential for bottoming or damaging the shock(s), which is not good. If the car is to be lowered, either new shocks with extended & compressed lengths to accommodate that change should be sought out, or the mount(s) may need to be modified to restore the shocks to a mid-travel position. At the very least, check the shock travel against suspension travel to determine whether there IS a potential travel issue.

I don't think it would be economically worth the effort to try to work out the Ackerman issues--if this was a full-out race car with race tires, the grip level would make that important, but with the weight of the car, the size and type (I assume DOT street-spec) tire is going to result in wheel-slip rates that would not change significantly regardless of the situation with the Ackerman effect.

I would take a look at the steering gear to see what can be done by way of bracing to stabilize the left frame rail--it's an interesting thing to watch the gear move even while static and see it "walk" back & forth with steering wheel inputs--not dramatic, but imagine how much it might move under dynamic load conditions. "

Well you would be surprised at how well you can make it handle without lowering it.

help me with a low buck road race only setup please...

Hi Guys- new here and have been researching posts for some time trying to determine suspension setup. I have a 1995 9c1 that I race in the 24 hours of Lemons series. I've run a couple races now and would like to get her to handle better, lower CG, & save tires. The car is gutted and...

www.impalassforum.com

I just wanted a few respected members to quote as counter point the opinions of the best handling is at the lowest suspension level.

 

Thank you for that, great thread reads.

Essentially my car is a clone of Ed's car, just a tad bit worse since I decided to center the rear axle which is more detrimental to performance. But I couldn't stand the off-center wheel.

There's ed talking to me at the nationals this year hah. if time permits next year at the nationals I'd let him co-drive my car at autocross if possible.

The only thing I would counter point to that post above is the bilstein ak1053 is the samething as the 1104, how do I know, well I swapped the 1104s only after 1-2 years of use thinking the ak1053 was a better match to the #750 springs, and I felt absolutely no difference. 91ss has some threads on it also where they are measured differently. The ak1195 is one i just tried and it felt better matched atleast on the street since those were meant for the crown vic cars that came with 700 pound springs from factory.


My primary reason for even looking into any of this is Brian's car this year att the impala nationals... when you're 5 seconds faster on a 1 minute autocross course than the 2nd fastest b-body and over 12 seconds faster on the road course than any of the other guys it's worth looking into.

I understand his car is gutted and has aero, but everything else is quite basic (not meant to be an offense, actually a compliment)

I've asked him for a picture of his frame to bump stop clearance because I'm curious as to what it is. In this picture he's on a 255/40/17 which would be 25", looks like he has a wheel gap of like an inch.

That being said since my car is used a lot on the street the current setup I have on now seems perfect, plus other than the pictures being inside the car it doesn't feel like it rolls much either. (no race seat or harness)

 

Didi you ever use the lap belt ?

 

.

 

Thank you for that, great thread reads.

Thank you for reading my posts, not just skipping over them.
I see you put time and money into your car then go out and use it.
There are a lot of people that bench race so I pay attention to those that actually use their car.

Today my brain clicked on the specifications I wanted to tell you about.

Several years ago the internet served up some documents that were interesting.
I found the Automobile Manufacturers of America (MVMA) sheets for some B bodies.
They are not definitive and one can see there was a lot of "cut and paste" on these forms with little proof reading.
Under front suspension I found the same information over several models and years (94-96):
Full rebound 4.3" design 3 passengers
Full jounce 3.4" design 3 passengers

As I said they list the same for the Caprice and Impala which does not make sense to me.
The form showed the different "F" spring rates.

Right or wrong what I believe is the jounce and rebound numbers are full design deflection at the tire's center line.

In my world I use the Caprice ride height as zero and subtract the lowering height from the jounce number.
So the Caprice wheel can be pushed up 3.4", the Impala 2.4", and if you lower a Impala 1.4" you have only 1" of jounce travel left.

My primary reason for even looking into any of this is Brian's car

when you're 5 seconds faster on a 1 minute autocross course

and over 12 seconds faster on the road course than any of the other guys it's worth looking into.

This reminds me of a sport car meet I went to.
When about half of the cars had made their first pass the group stopped and complained to the officials that the course was "too tight", in the corners. No one wanted to show up to help layout the course but they blamed the two Miada owners for designing a course that was too small.
One of the course designers borrowed a ford stretch cab 8' box F-150. He ran it at speed through the course (no drifting allowed) and the officials ruled this would be the "minimum qualifying time" Hondas, Toyota, Minis etc... failed to qualify.

Whether it is nascar, formula, indy, or sport car racing you will hear about drivers that win with car setups that other team drivers could not use.

Some drivers are very good with setups that only work for them and do not make sense to engineering or other team drivers.

My personal opinion is 1" is not enough jounce for street or track even with 750Lb springs.
My worry is that repeated flexing at the suspension limits will increase maintenance cost or do damage.

I can easily be proved wrong by anyone who removes the front springs and documents total suspension travel (7.7" at the tire center line?) and bounce and jounce distances for Caprice or Impala.

Ed's comment that the front suspension has a "ideal geometry" range is something I believe but do not have the knowledge to debate.

 

What may be helpful for auto-x may be counterproductive for the road course. Which is far more challenging as well as infinitely more fun. Suggesting that lowering the car's center of gravity is of no advantage flies in the face of reason. In my opinion, auto-x is much harder on equipment than the road courses. For that reason (and, others) auto-x has become my least-favorite event