Composit spring rear, how stiff?

[Ricky]

Hi.

Im just in the process of finishing off an upgrade of the chassie of my 72 convertible.

I really enjoy driving, both on roads and at the track.
With the original setup the car was OK on the road but way to sloppy on the track.

My plan was to go for the complete coilover convention but i figured out that i would propably not spend so mouch time at the track to get everything sorted when i comes to springrates and adjustment of compression and rebound of the absorbers.

So to make things easy i went for the VBP "Transverse Composite Monospring" kit at the front end instead since this kit also alows easy rideheight and "stiffness" adjustment.

I chosed the 1-1/8” front swaybar and the 7/8" rear and a set of Bilstein gas shocks.

I car already had a 330lb monoleaf spring fitted in the rear but...

It accidently got damage when the car was in the garage (please dont ask me how it got damaged).

Now to my question..


What springrate for the rearend may be the correct for my car?

The car is a fullweight bigblock car.

It will run on the road but handling is a priority before comfort (it should be fun to drive).

Lets put it like this, more track than roads.

 

[mrvette]

I know nothing of front transverse mono springs.....that came out well after I did my 460 lbs VBP front springs....

I have had a 360 lb REAR plastic VBP monospring for some 16 years now, and it's been fine....at first I had KYB shocks, and got convinced to buy Bilsteins some years ago....and with I knew of them earlier....well worth the money....I can go over a undulating bridge here at speed and not have a bounding ass....huge ride comfort improvement.....second off, I have a stockish rear sway bar, the large bar was way too much for my ass on these rough roads, kicked it all over the joint......and as a result, I lightened up on the front bar also....

then again, it's all depending on the tires...I have 17x9.5" rims from a '89 vette on there...same size for years...and so all else stops there, you know, where the rubber meets the road....

:smash::quote:

 

[Ricky]

Thanks for your reply.

The 360lb spring sounds like a reasonable solution.

I wouldnt want to spend money on something to sloppy but on the other hand i also want the car to perform well on the track.

I run my car on stock 15x8" with BF Goodrich 255´s on the road and 15x8 American Racing 200s whith track tyres on the track.

So the car gets a lot of rubber between the rims and the tarmac witch will soften the ride a little, at least on the road.

//Ricky.

 

[Ricky]

I havnt been able to find any recomendations anywhere for springrate relations front/aft for track use.

I understand that this is a very dynamic subject but there must be some templates to follow somwhere?

 

[mrvette]

Out of my league with track use man....others know far more...

my comments relate to street driven daily over some pretty bad roads...

and spirited driving....do the Bilstein shocks....far better than the KYB....

other than that, I can't really help, I ditched the 15" stock rubber/rims when I got the car...so i'ts been a while....

except to remember really clearly, with the stock steering, the car tended to follow road ruts, constantly fighting the wheel....
result of my swap to better wheels/tires...

my rack/pinion swap cured that....other options maybe work well also, like the Jeep box conversion...Borgeson makes that option easy....

:bump:

 

[Ricky]

Out of my league with track use man....others know far more...

my comments relate to street driven daily over some pretty bad roads...

and spirited driving....do the Bilstein shocks....far better than the KYB....

other than that, I can't really help, I ditched the 15" stock rubber/rims when I got the car...so i'ts been a while....

except to remember really clearly, with the stock steering, the car tended to follow road ruts, constantly fighting the wheel....
result of my swap to better wheels/tires...

my rack/pinion swap cured that....other options maybe work well also, like the Jeep box conversion...Borgeson makes that option easy....

:bump:

Thanks for input.

I have used the Bilstein shocks for a year now and they work well.

I have upgraded to a Steeroids R&P and the "ordernary" full welding/boxing of the frame together with solid engine mounts.

The car is not street ready just yet so i havnt had a chance to test it out but it appears to be far more stiffer/solid in the frame and suspension so far.

Really looking forward to test it on the road/track.

 

[mrvette]

Out of my league with track use man....others know far more...

my comments relate to street driven daily over some pretty bad roads...

and spirited driving....do the Bilstein shocks....far better than the KYB....

other than that, I can't really help, I ditched the 15" stock rubber/rims when I got the car...so i'ts been a while....

except to remember really clearly, with the stock steering, the car tended to follow road ruts, constantly fighting the wheel....
result of my swap to better wheels/tires...

my rack/pinion swap cured that....other options maybe work well also, like the Jeep box conversion...Borgeson makes that option easy....

:bump:

Thanks for input.

I have used the Bilstein shocks for a year now and they work well.

I have upgraded to a Steeroids R&P and the "ordernary" full welding/boxing of the frame together with solid engine mounts.

The car is not street ready just yet so i havnt had a chance to test it out but it appears to be far more stiffer/solid in the frame and suspension so far.

Really looking forward to test it on the road/track.

Saw your thread with the photos of what you have done, you are much further along than I had thought, you maybe need better input on that rear spring, as I don't race my car.....I have seen guys liking the dual mount rear plastic springs much better, and even some with coil overs and modified rear suspension so much it don't even look like a shark under there....

this is one of those threads I will be learning on....:thumbs:

 

[Ricky]

Thanks.

I believe the "dual mount monospring" could be a good solution, then i get some posability of adjusting the stiffness of the spring.

However it would have been nice with a general template for the springrates.

I believe there must be a reasonable relationship between the stiffness front to rear.

Not only on the track but also on the road.

//Ricky.

 

[mrvette]

Thanks.

I believe the "dual mount monospring" could be a good solution, then i get some posability of adjusting the stiffness of the spring.

However it would have been nice with a general template for the springrates.

I believe there must be a reasonable relationship between the stiffness front to rear.

Not only on the track but also on the road.

//Ricky.

VBP should know their own products there pretty well, I have no complaint over the 16 years their stuff on my car.....100k miles......so maybe talk to them about a matchup for the rear....Marck, TT should be along, he heavy into all this suspension stuff, other know more than I do...

:clobbered:

 

[SmokinBBC]

Thanks.

I believe the "dual mount monospring" could be a good solution, then i get some posability of adjusting the stiffness of the spring.

However it would have been nice with a general template for the springrates.

I believe there must be a reasonable relationship between the stiffness front to rear.

Not only on the track but also on the road.

//Ricky.

VBP should know their own products there pretty well, I have no complaint over the 16 years their stuff on my car.....100k miles......so maybe talk to them about a matchup for the rear....Marck, TT should be along, he heavy into all this suspension stuff, other know more than I do...

:clobbered:

VBP recommends 550lbs front coil and 360 rear for BB street. 420lb rear for racing applications.

I have the 550/360 with bilstein sport. Rides well on the street. I don't race it.

 

[Ricky]

Thanks for the input.

I just minutes ago placed an order at VBP for a "Rear Dual-Mount Spring Kit".
http://www.vbandp.com/C2-C3-Corvett...ms/1963-79-Rear-Dual-Mount-Spring-System.html

I then get the same posabilitys for adjustment of spring stiffness as i already have in the front end.

Then i can "try and learn".

 

[turtlevette]

As someone who has extensively tracked their car, i can tell you your rear setup is going to make that thing tail happy as hell. Stiff rear shocks, stiff rear spring, and a 7/8 swaybar on the rear.!

The good news is that dual mount spring has adjustability. I doubt you'll ever get close to the max stiffness setting. Or you might want to lose the swaybar and compensate with the spring setting. The upside of no rear swaybar is you can run a fatter tire. What's the highest effective front spring rate with that front tranverse spring? You'll probably want to make the front as stiff as possible to compensate for the very stiff rear.

The only way i can get my rear to plant is to dial in about 5deg of negative camber on the rear. You'll probably want to do that too. Maybe go 3deg.

 

[MYBAD79]

The dual mount rear spring is probably the best match for the front dual mount that you already have. I hope the kit was sotill on sale when you ordered.
I have a feeling I might bep orderingbtheir front kit once the rear kit is installed and I drove a few miles... :1st:

 

[Ricky]

The dual mount rear spring is probably the best match for the front dual mount that you already have. I hope the kit was sotill on sale when you ordered.
I have a feeling I might bep orderingbtheir front kit once the rear kit is installed and I drove a few miles... :1st:

Yep, VBP charged me 419.99 usd for it.

Ordernary price at VBP was set to be 569.99 usd.

Ecklers asking 619.99 usd for the same kit..
Club Corvette Sweden has a good discount at Ecklers but in my opinion they sometimes are totaly catastrophic in customer support when it comes to information of an order, tracking numbers and discounts and so on..:crap:
So the last couple of orders has been placed at other companys.