mx5racer

I search the archive and could not find this information
I found it on another site
thought that this might be helpful to others

2003/2004
Spring Rates, Front/Rear, *lb/in:
Base 440/577
MSRC 457/577
Z51 525/634
Z06 525/714

John Shiels

This was discussed in road racing section manys times but no real proof was ever found to my memory. Chevy won't release it.

davidfarmer

You need to note, that due to the impact point, comperable spring rates with a coil-over type suspension drastically lowers the equivalent spring rate on the C5. And its' different front and rear

For instance, my 800lb/in front = around 600lb/in mounted at the shock position, and my 600lb/in rear equals a 500lb/in coilover.

AND, it is a PITA to actually measure them!

Jim 47

Right Dave. The shock mounting position on the lower "A" arm on both the front and the rear of the C5 is further out on the A arm giving that mounting position a longer lever arm from the pivot points of the lower A arms, and thus a greater mechanical advantage to support the sprung weight of the car. As a result, the spring that supports the car's weight at the shock mounting position doesn't have to be as strong as the "stock" spring mounting points, which are closer to the pivot points of the lower A arms.

The data that is printed above in the original post agrees with the data that I have on the C5's spring rates. It's interesting to note that the rear springs have a higher spring rate than the front springs. In itself, that means nothing since the real force to counter the car's sprung weight and provide the desired ride height is determined by the geometry of the suspension, the spring rate as well as the geometry of the spring.

Of course on the "stock"C5 the front and rear roll stiffness is controlled by both the spring rate and the stiffness of the stabilizer bars, thus a much larger and stiffer front bar compaired to the rear bar. And , of course, the shocks have a definate influence on the roll stiffness also plus a lot of other functions.

If the above data are correct, (Z06: F=525 #/in, R=714 #/in), and the Z06 isn't a bad handling car, I am confussed about running an 800# front and a 600# rear spring plus the T1 anti-sway bars. Without knowing all the variables and imperical data about your application of a front 800# and a 600# spring, it would seem to me that that combination of springs and anti-sway bars would result in a lot of understeer.

I think that John Sheils also runs an 800# front spring, which is considerablly stiffer than the stock spring, and a stock spring in the rear. Again a recipe for lots of understeer.

I've seen you drive Dave and it sure doesn't look like you have and understeering car, and I don't think that John has a problem with understeer either. So, what am I missing, or are the data above incorrect?

:confused: Jim Helm


[Modified by Jim 47, 7:40 PM 12/14/2003]

vettethret

What coil over spring rates are the MAX you would run on a street car? I have Rippie 550lb front and 650 lb rear and the car seems to bounce. Any help would be appreciated. Sorry about the hijack! :crazy:

till

This has been discussed before, and I don't think there ever was a poper explanation. If the spring rates are given correctly, there should be a lot of understeer.:skep:

I have 500lbs front, 650lbs rear hypercoils and the car doesn't bounce. Due to the stiff spings there is more movement on uneven surface, but no bouncing. Sounds like your shocks are not set properly.

Till

vettethret

Now I'm more confused. I even had Bilstein make a shorter shock body for the back so there was increased suspension travel. I'm going to a high line alignment guy who does a lot of racing applications. Hopefully he can help. Were basicall running the same package, my springs are hyperco to. The shocks are from Bilstein so I dont know the shock valving. I have the car slammed but with the shorter shocks it shouldnt be due to travel. My 02 coupe was just as low and rode better with the much cheaper pro shocks. Do you think going down a 100lbs in front and back would make a noticeable difference in ride quality? :cheers: :yesnod: :flag

till

Maybe it's just the bad road surfaces in Orange County? :D

I do have Penske DA shocks, but I only got them three weeks ago. With the initial setting there was a lot of movement following bumps. I increased compression stiffness, and it actually smoothed out the ride. Maybe you can get the shocks revalved. I heard Bilstein in Germany charges about $30 per shock.

Or you could get softer springs, which would be about the same price.

Till

till

Just noticed that. Is your car actually as low as in the picture? How far can the wheels move up without hitting anything?

Till

vettethret

It is very low. I dont rub at all. I have the T1 sway bars as well. The roads here are actually good but I can feel evrything on the road. That is fine but when I hit bumps in the road the car doesnt take them well and seems to bounce like in the old MINI TRUCK MULLETT DAYS! I should still have plenty of travel. I'm thinking since I had lighter springs on my coupe, which was a heavier car, the springs may be to much. I LOVE a stiff ride but not when it bounces. I'll let you know what happens at the alignment shop. He says he can determine travel once it's up on the rack. Hopefully I just have to lighten the springs a bit. :cheers: :thumbs: :party:

John Shiels

My front is 1000 and the rear was 796 I have the T-1 bars. I am no expert but I don't feel it has understeer. If anything I think I have a tad oversteer. I can't analyze much I just want to beat it :D My car doesn't dive under hard braking anymore. It seem to handle good but I have not driven anything else. I think I had a 825 in front but wasn't very good. My shocks needed a rebuild so I introduced two varibles at once. I am happy now but would like someone like Lou or Dave to drive it and see what they think.


[Modified by John Shiels, 6:26 PM 12/15/2003]

vettethret

I assume your running the leaf springs? :cheers:

John Shiels

Vette Brake Products :yesnod:

0C5stein

Racing a street car is always a compromise, that being said and considering that I drive on the street alot more than the two days a month on the track, I went with relatively soft spring rates for coil overs.
I'm running 400# coils in the front and 500# coils on the rear. My car rides very well, and handles well on the road course as well. I'm sure that I could shave some time off on the track by bunping the spring rates up a bit. I did try 400 in the front and 550 in the rear and that car was not as well balanced. As a matter of fact it kept going sideways through turn 9 at Sears Point (High speed sweeper). I probably should have gone up 50 lbs in the front, but I could get my hands on the front springs before our next track day so I dropped the rears by 50.

Before they repaved Sears Point there were some parts of the track that were rough and the softer rates seemed to nail the rear down better.

I would recommend 400front/500rear or 450front/550rear and still have a good street ride for even long trips.

My shock valving is also adjustable so I can play with that as well.

I hope this helps.

Where do you live? So Cal?
My shop is in the Sacramento (Nor-Cal) Area and If I can help, I would be happy to.

Mark

vettethret

Thanks for the great info mark. Today I ordered 450 front and 550 rear. I love a stiff ride but its so hard now the car is bouncing to much. I hope it softens the ride. In hard corners it gets upset when the road isn't smooth. I notice your in Roseville. I grew up in Sac and moved from El Dorado hills. One reason I went firmer on the ride is that I knew the car was going to be slammed and I didnt want the wheels poking the wells. I'll let you know how it works out. :cheers: :flag :party:

0C5stein

You are very welcome. Let me know how it goes.
What diameter spring are you running?
Are they hitting on the upper a-arm in full droop? I've seen several problems with the longer travel shocks being combined with 2 1/2" coil over springs and the 2" springs are blowing the top spring perch apart.

The Riley racing kit that is being tested on my car should be released in the next month or so. It is very tunable and looks to price out at less than $2k with springs and adjustable valved shocks. This kit has solved the failing top shock mount syndrome of alot of the other C5 coil over packages.

Stop by the shop if you ever find yourself up here in Roseville. There is always something interesting going on.

Today we have one car getting a $6k+ stereo installed by your's truely, my partner is installing a Vortech supercharger on another car, we have a pewter coupe for sale for one of your customers and are installing a road course brake upgrade on a Z06.


[Modified by C5stein, 6:58 PM 12/16/2003]

vettethret

Of course its coming out next month, I just spent the same on non adjustable coil overs. I actually went with the Rippie kit. Initially I only had .5" of travel in the back and Rippie said they didnt know what to tell me. WCC did all the work on the car. Craig, the owner did some research and had Bilstein make a 2" shorter shock body. I then got the shorter springs. All I know is that they are Hyperco springs. The mechanic said the front still had 2.5" of travel so we left that alone. I got the car aligned at a shop West Coast recommended and they told me the springs were to stiff. This is compounded by the fact I have no side wall to my tires, 19 + 20" I think and hope the softer springs will solve the problem. I might come up there in two weeks to visit a buddy. If I do I will definatley stop by your shop. :cheers: :yesnod:

0C5stein

That would be great. I would love to meet you. You can't have too many Corvette friends.

Are you driving your C5 up here?

I would love to take a look at your setup.

You can never learn too much either.

Doug Rippie and I both started out racing in SCCA at about the same time. He and his team really kow alot about road racing Corvettes. Of course we both have our own ideas as to what is "best". Dougs stuff is mostly set up for the track. My stuff leans heavier toward setting them up for the street , but still being good at the track.

I'm sure you will like your new springs alot more than wjhat you have now. With 19s & 20s, I'm guessing that your overall tire diameter is a bit more than stock. If so, watch out for rubbing in the rear wheel well. A little rub will wear a hole in it in a hurry.

vettethret

Yes I would be driving up. To be honest with you Rippie has terrible customer service. They made no effort to figure out how to get a shorter shock body made.WCC sis all the research and got it handled. If they run race cars then you think it would be a no brainer since race cars are dumped. They did this to me once before on my collectors edition LT4 with a coil over set up. Sold the car before I could figure out what to do about travel. I wont use them again and will only use forum shops for purchses. I will let you know what dates I'm coming up. I definatley want to check out your shop and have you eyeball my Z. :cheers: :flag :party:

vettethret

P.S. The diameter of my tires are exactley what stock is. I'm running 275/30/19 and 305/25/20 conti sport II. The back diameter is 26.0 and stock is 26.1. Not sure about the front. :crazy: