Stingraynut

I had new shock absorbers fitted - 'Comfort VRX' supposed to give a soft ride but my old worn ones were softer.

I'm disappointed, it hasn't fixed the concrete feeling at all. It was a fairly expensive exercise to get no-where - Aus$520.

I had done almost 12 months research, got lots of advice here and had decided my old shocks had gone hard.

So it must be the springs (I have the softer of the two options, Z52 on my 1988) and also I expect that the thin walls on the 17" rims contribute.

I have plenty of suspension travel and I'm not bottoming out. My suspension bushes are OK.

When I hit a hard bump like a railway line or a pothole it's really bad. Knocks out my fillings, makes a loud bang and throws the car off line.

I know it would be cheaper to get false teeth - BUT - is there a softer aftermarket spring ? that doesn't affect ride height ?

I had an idea yesterday, feeling a bit desperate - my idea is to get some great brain to compute what size and position of holes could be drilled in the spring to make it more flexible.

I think it would be possible - anyone like to comment ?

S'nut

86PACER

Drilling holes in your front spring? I can't see how this would be a good idea.
Wouldn't that weaken it and make it prone to cracks? It would be easier and safer to just install a softer spring.



[Modified by 86PACER, 2:44 AM 3/19/2004]

1989redvette

i don't know how to fix your probelm...BUT DO NOT DRILL HOLES IN THE SPRING!!!! you are asking for big trouble..nexttime you go overthat railroad track it would probally splinter!!! accident waiting to happen :nonod:

BigC4

I don't think there is anything that can be done to the spring to make it weaker (in a safe way). As far as softening the ride, if it is that bad, replace the spring with coilovers, use longer springs with lower spring ratings and adjust them to the stock height.

Gary04Z06

Check out http://www.vbandp.com, they should have softer springs. They will also do custom spring rates.

boxerdog

I have an 86 with Z-51 and finally got tired of the too stiff suspension. I replaced the springs with a pair from Vette Brakes. That made a world of difference, it's perfect now.

The only minor problem is that in spite of everything that GM said the original springs do sag after 10+ years and when you put in new springs the car sits higher. In my case it was even slightly higher than the stock height. So I lowered the car by taking out the blocks on the front spring and using longer bolts in the back.

Aggravated4life

Dont forget,you car is old now,and the bushings have used their life.I replaced the rear bushings in my 86...they looked fine but when I took them out they were real bad.Dont assume the bushings are fine after all these years,even if they appear ok on the outside.

Rebuilding the suspension with all new bushings and softer springs should help a tremendous amount then just doing the springs alone.Before my bushing change,the car would BANG over bumps real hard,especially from the rear.Now they make a quieter thump.I still havent done the springs yet either.Need to do the front bushings and possibly springs later.
:crazy: :)

c4cruiser

According to this suspension chart, http://corvetteactioncenter.com/tech/c4/susp_chart.html Your 88 with Z52 has the same spring rates and sway bars sizes as the base FE1 suspension. The shocks on the Z52 option were different. Take the chart with a grain of salt as I have heard that not all of the data is accurate. Hib Halvorson built the chart a number of years ago and I think it has only been updated once since then.

You could experiment with tire pressures a bit but I wouldn't go much below 28-30psi.

Definately DO NOT cut holes in the spring. The material is laminated fiberglass and it will shatter if something weakens it. Vettes do ride stiffer than a lot of other sports cars and GM even made the base springs softer over the model year runs of C4's The 96 is supposed to be the softerst riding of all. The 84 car, at the other end of the spectrum, is very stiff riding compared to other years.

Contacting Vette Brakes is a good suggestion to find out what they can do for you. But one thing about going too soft is that you may sacrifice some handling characteristics.


[Modified by c4cruiser, 8:34 AM 3/19/2004]

1SLO POK

I had the same problem when I hit a pothole, BANG! My problem was worn bushing on the rear control arms, they looked fine on the car but when I took the control arms off to get a better look the bushings just feel apart.

I also installed some Edelbrock IAS shocks in the rear, and know the car rides great. I wish I would have down this years ago. :thumbs:

Stingraynut

I'm not about to drill holes in the spring, I realise it could encourage the spring to break - although I reckon it could be done if designed properly.

A better idea would be to shave the spring slightly - once again it would have to be done scientifically.

Thanks for the link to Vette Brakes, looking at all the suspension stuff that could be replaced is interesting.

I checked out the coil overs last year but it was an expensive exerecise. I can see that it is a solution.

I'm planning to go back to the suspension shop that fitted the shocks last week - these are harder than the ones they took off, they had to cut two of them so can't just re-fit, otherwise I would. Maybe the shocks can have larger valves, but I doubt it's possible to get that done.

I'm not concerned with the 'roadholding/cornering' ability because I don't have any now, our roads are rough and I can go faster round many corners in our 'shopping car' than I can in the vette.

I don't believe that stiff suspension is any good in real life, on ordinary roads - I kept this comment from a forum member last year - "We have county lanes with bumpy corners in the UK and the vette was an absolute pig to control when driving 'fast', you couldn't keep your line, the car litterally bounced its way round. (you could corner faster in an escort) Stiff shocks and firm springs used to be the hot ticket for a good handling car, but I think most savvy people now know differently, especially on a car that is used on the street regularly"

Here in Cairns our roads are a bit similar plus we have sugar cane hauling rail tracks across the road everywhere - these are about half the width of standard rail tracks which seems to make the jarring worse.

I'll also plan on replacing the bushes as suggested, thanks to everyone for their links and comments.

St-st-st-st-i-i-i-ng-ng-ng-r-r-r-r-aaaaaaa-y-nut (sorry, I wrote this while driving down the road)

Caliburn

I hate suggesting someone spend money on something, since this is all based on opinion and relative experiences - but the Edelbrock IAS shocks made a big difference with potholes/RR tracks/etc. on my 96. If the bump is big enough to activate the IAS second circuit, it is handled much better by the Edelbrocks than by my stock 96 shocks. Since enough people have said don't drill holes in your spring I won't say it again. I have heard good and bad about VBandP custom springs - suggest searches here and autocross section. A set of 96 base suspension springs might be a good alternative.

Stingraynut

I wish now I had ordered some shocks instead of spending over $500 last week on these ones, as I said before, it was a fairly expensive exercise to get no-where.

Shipping time was quoted as 3 months plus there'd be duty, GST and so on to pay. I decided to buy locally.

I know the shocks are at least partially responsible for the harsh ride because these new ones have made the ride worse. They're even picking up minor corrugations in the road just 50metres from home that I never felt before.

I'd re-fit the old shocks but they had to cut two of them to get them off - I reckon they were original AC Delco's.

I forgot to say thanks to C4Cruiser for the suspension chart link, it's always good to have facts. I have a hard time understanding what I'm reading there, not sure how the spring rate is measured - I know that if I push down with 87 kilos on the front fender it only moves about 20mm (3/4")

My 88 has good ride height, I don't see any spring sag at all which is surprising on a 16 year old car, I wonder if it's had a spring replaced at some time and they've used a harder one like off an 84 ? Anywhere I can check on the spring ?

S'nut

xs650

Is there any chance you can get a ride in or drive a simmilar Corvette to compare? I expoct they are about as common as Polar Bears in your neck of the woods, but it would be worth some $$ and effort to arrange it before you started pissing away large amount of money on more parts and labo(u)r.

I'll second the advice you got on bushings. They might be a bit of a long shot, but bushings are kind of like the foundation for your house. If they aren't right, it doesn't matter what you build on top of them. With the age of your car, shey probably need replacing anyway. I have also pulled out bushings that looked goodoutside and found out they were crap, so you can't judge by how they look outside.

Have you asked any of the good aftermarket suspension suppliers if there is anyway to identify which springs you have? They are most likely marked somplace. Probably someplace where you have to take the car apart to find the marking :smash:

Don't even think about shaving the spring. That doesn't work with high strength compost parts unless you want them to do an unscheduled self disassembly while understress and show you what's on the next layer below the surface. :lol:

Stingraynut

Thanks xs650, the analogy of the bushings and house foundation is a good one. Currently don't know where to start on that, I'll go looking for bushing kits and see if there's any tech tips.

Since hearing about the bushes here, I've been thinking about them - after all, something must make the crashing noise, otherwise there'd be a silent jarring - and maybe a silent jarring would seem less offensive.

Shaving the composite spring ?- what ? Me?

Currently I have no contact or see another C4 in my area. In July I'm driving down to Brisbane - about 1000 miles - and will catch up with some contacts down there, will definitely make sure I get some rides and see what's normal.

I was trying to fix the harsh suspension as one of the many things I'm doing to prepare for the trip.

I bet you're right about the spring ID being somewhere unreachable.

S'nut

Stingraynut

Thanks for the ideas - especially the re-valving, which I was considering. My new shocks are less than a week old - I'm going back to the suspension shop which is a well known Aussie brand name. I believe the valving is way too firm, maybe OK for a heavier car but not the vette.

The 96 springs sound good, that's a long term project because of the shipping etc, can't just walk into a wreckers and find a C4 - nearest one is probably over 7000 miles away.

Being new shocks I doubt that they are letting the car re-bounce - they're hardly letting the car bounce once !

In fact I think that the rebound damping is the only thing that is better than before. It's the tyres leaving the road when hitting a sharp bump that is causing the poor road holding. The tyre probably doesn't leave the road just go up enough to loose grip.

Also of interest is that running low pressures on the 275x40x17 makes the ride worse and high pressures are better - I've tried all pressures from 29psi up. I used 34psi for a few months and went to 36.5 which was an improvement - how high is it safe to go? I'm thinking about going to 39 ?

S'nut

speedjohnson

What a woosy.

You need to go find a base suspension C4 at a wrecking yard and rob the bars + springs. Then go buy a set of KYB gas shocks...that'll definately soften things up a bit.

You can probably just post a "trade" on the C4 parts forum and get this all for free.

Or, you can do like me...just suck it up and put a few pounds on your butt for cushion.

Is there a chance that what you're actually feeling is a suspension that has too little dampening on rebound? I mean, if what you are saying is that the car just bounces all over the raod over the bumps, then maybe what you are decribing is a suspension that is too compliant or one that lacks the proper rebound dampening. Think about this. If you decide that what is really happening is that you get three bumps when you've only gone over one bump...then try going back to the stock Bilstein shocks. Maybe your aftermarket shocks are stiff in compression and too light in rebound dampning? sj


[Modified by speedjohnson, 6:03 AM 3/22/2004]

Mr6spd

the 96 models had super soft springs ... get a new or used set of those.

vader86

DO NOT drill holes, call VBP and have them make a custom set for you.

h rocks

Nut-You definitely have the wrong shock setup for your base springs. Without knowing the bump and rebound valving values, my guess is that you just plain and simple have too much of both. Because of how and where I run my car, I have the same basic spring setup as you do, but I had my Bilstein FX3 shocks re-valved. Without going into a lot of detail, it's given my a tremendous amount of flexibility, and a certain amount of tunability. On full "soft" the shocks are at their "softest" valving. This allows quite a bit of rebound, so that when you "compress" the springs, the energy is allowed to release fairly quickly, yet prevent a "wallowy" condition. At full "Hard", the bump and rebound are at their "closed" position, and offer maximum control.
I don't know what the import duty rules/laws are in The Land Down Under, but if you were to obtain a set of used, "junk" shocks in the US and have Bilstein re-valve them to YOUR requirements. (Just tell them what you want, and about your back surgery) You should be able to get a set of 4 for ~ $250USD. Also, you could get a used set of "base" springs from a '96. The combination of which would definitely soften up the ride to the point of being very back friendly, yet not make it a wallowing pig as a daily driver. Would you still be subjected to GST etc?





[Modified by h rocks, 4:09 AM 3/22/2004]

xs650

[QUOTE] Also, you could get a used set of "base" springs from a '96. The combination of which would definitely soften up the ride to the point of being very back friendly, yet not make it a wallowing pig as a daily driver. Would you still be subjected to GST etc?

Be aware that only the base coupe springs are the soft ones.