Spring rates

Chris E · 17th March 2004, 12:11 PM

Any suggetsions for the best spring rates for the front of my KVA?

It will be mainly used for road use.

Thanks

40 Bud · 17th March 2004, 12:14 PM

I think you will find 225 to 250 good on the front combined with 300 to 350 on the rear.

John · 17th March 2004, 06:49 PM

I'm again amazed by how well these cars can handle with such mild spring rates. Gotta love lightweight cars! Heck, the front coils on my '68 Camaro are 600# rate!

John

Jools · 17th March 2004, 08:11 PM

Chris, have a look at the Eibach range of main springs with progressive tenders. Not overly expensive and give you great on road ride quality, but stiffen up brilliantly when you take your 40 out to play on track.

Howard Jones · 17th March 2004, 10:26 PM

Buds Gonna have a cow but I just ordered 300s for the front and 450s for the rear. I kinda like em a little stiffer.I'll add that after really doing a lot of work with the shock length question here's what I have come up with on a GTD. 14.75" fully extended. You will need min of 3.5" travel and min lenght should be 10". Now I know that these numbers look like a 13.5" shock but the bump rubbers will take up about 1.5" Mesurements are center of mount hole to center of mount hole top to bottom.

Iron Sheik · 17th March 2004, 10:47 PM

Admit it,,,,,you liked the ride in my car,didn't you?!!

Malcolm · 18th March 2004, 07:02 AM

I use 450 lbs front and 500 lbs rears on my GTD but feel it is getting too stiff for road useage. The rising rate springs Jools mentioned are excellent and are where I wish to go next.

The record for stiff springs on a GTD must surely go to Anders Hildebrand (before he sold the car!) who had 1000 lbs front and 1100 lbs rear springs on his pure race GTD Mk11. I think he was using the chassis as a torsional bar!

Malcolm

Howard Jones · 18th March 2004, 03:21 PM

Ya Fred I did. I'm talking about faili's car. He has 450's on the back and it feels real nice. The big tires might be part of it but it still feels good to me, not TOO stiff.

James · 19th March 2004, 07:19 AM

I was going to use 450 on the rear with 400 on the front.

But the MDA is a lightweight 1050kg-1100kg (2350lbs) so I might go down to about 375 rear 325 front.

Time will tell.

450 for the rear of a GTD sounds just right though. I think they weigh about 1250kg (2750lbs) approx. Some are heavier though, and of course some are lighter. Springs are quite in-expensive so at least if you get it wrong you can try again until you get it spot on.

Regards,

J.P

Linder · 19th March 2004, 09:40 AM

hello
I have a kva where i am about to buy my suspension.I have read a lot about the suspension to use. I am mainly gonna use the car for road but if I get the oppotunaty to go on track i will.anyway could somebody suply me with p/n for the suspension to use and maybe where to buy.live in denmark
best regards
MIchael linder [img]/ubbthreads/images/graemlins/grin.gif[/img]

Devin · 20th March 2004, 05:20 PM

Lindler,

I thought you were trying to sell your KVA??

I guess you must have had second thoughts or your personal situation has changed plans.

Anyway good luck on the build...I wish I at least had some parts of a GT-40 in the garage even to look at!

Devin

Linder · 21st March 2004, 10:11 AM

Hello
It was my intention to sell but luckely my father and some other guys from this site helped me change my mind.Thanks [img]/ubbthreads/images/graemlins/grin.gif[/img]
I really like this site it helps with everything
but anyway i could still use some help to find the right setup for my kva.
best regards
michael linder

Hemipanter · 28th March 2004, 12:28 PM

[ QUOTE ]
Any suggetsions for the best spring rates for the front of my KVA?

It will be mainly used for road use.

Thanks

[/ QUOTE ]

Anyone having the geometric numbers for the GT-40?
Like A-arm length, mounting points for coilovers and bars.
Frontand rear axle weights and cgh. I created a program for the Pantera that should be easy to use for the GT-40, to calculate Hz number and springs-bars. If anyone is tecnicalyy informed about the car concerning specific numbers you are wellcome to make contact.
Goran Malmberg

Kalun D · 28th March 2004, 11:38 PM

Don't know if they have anything like this in Europe but in the states one manufacture that I know of, Aldan, will sell aluminum, adjustable damping, rebuildable coilover shocks and allow you to exchange springs if what you purchase initially doesn't dial in properly. Just as long as you don't scratch them up.

That's exactly what I ended up doing on my Cobra, and the 40 will probably be the same.

Aldan's might not compare to a full on top line race shock but they are good for street, light race use.

They apparently don't have a website or I'd post it for U.S. builders. They are in Carson CA 310-834-7478

I'm not suggesting you get these shocks because shipping is prohibitive, just find someone locally that has the same spring exchange policy.

Some ballpark figures for what it's worth I'm running 300#'s on the front and 350#'s on the rear

Brian Kissel · 29th March 2004, 01:02 AM

I don't know if anyone recognize's the name "Goran Malmerg" or not. He is the gentleman that I refered to back on Jan.01, 2004 that has built the Pantera with the 700hp plus Hemi in it. Here:

Hello Bill !!!!!
Reading your post about the Hemi, also sparked a memory. How about a Pantera with a 526 cu.in. Hemi in it, and weighing in less than the original with the 351 engine. You can find alot of usefull information on this fellows website. Go here, Hemi Pantera and then to the bottom to read about his build. There is some very good information about chassis and suspension build up. There are not a lot of Lola T70's around, but I for one would love to see one with a Hemi in it. ::::::

There is some very good reading about suspensions on his website. He has defineitly put a lot of thought in his car, and I personally have put the information on his web page to good use. I especially like his custom built rear uprights and hubs. I think it's worth a look for anyone still undecided.

Regards Brian

Tony Jasper · 5th May 2004, 12:01 PM

Hi Chris,
As all GT40 vendors suspension specs differ, only those pertaining to your KVA are valid. I have a type C KVA with 400lb front and 600lb back, and it works well. Bear in mind though that mine has an all-iron Ford 302, and if yours has any aluminium engine parts, then I'd suggest going lighter on the springs. Dampers are Avo adjustable.

Chris E · 5th May 2004, 12:13 PM

Thanks Tony
I went for 250 front and they seem OK but did settle a LOT during the first drive - ending up with 1.5 " ground clearance which was not very clever. I now have it properly set at 4.5" and all seems OK. I have nothing to compare it with though, so this is only my experience.

I'm now renewing the rears ( AVO's bought at the show on Sunday ) and will probably go for 350 springs (as my engine is lighter than yours) - unless anyone tells me different!

Trevor Booth · 12th May 2004, 05:13 AM

I can give you some numbers on suspension geometry and weights incl hubs and wheels that will be reasonably close. I do not have front and rear weights or cg (x,y,z coords) as yet

Hemipanter · 15th May 2004, 12:36 PM

[ QUOTE ]
Any suggetsions for the best spring rates for the front of my KVA?

It will be mainly used for road use.

Thanks

[/ QUOTE ]
Spring rates is allways subject for discussion. For a road car like this I suggest 2Hz to be a good compromise. And what is 2Hz??? This tells how hard the car is sprung, and is the wheelrate in p/inch in relation to the sprung masses. Wheel rate is the spring rate via the lever of the A-arms.

If the A-arm is 12" long and the spring is mounted 6" in from the outer ball joint (1/2 the distance) we have 6/12=0,5 Mr=0,5. (Mr = motion ratio) To calculate wheel rate Wr=Mr*Mr. 0,5*0,5=0,25. Then Wr=0,25*the spring rate.
Then if we have a spring that is 300p/inch, Wr=0,25*300.
75p/inch at the wheel.
As the Mr is squared the rate falls of fast as than A-arm spring mounting point is moved to the centre of the car.
And it is the rate at the wheel that is of importance for the car.
Sorry to say that things are even more complicated. If the coilover is tilted to the centre of the car, the distance lever is altered and not at the A-arm mounting point. It is at a 90 degree angle from the centreline of the coilover down to the inner mounting point of the A-arm.
Goran Malmberg

Hemipanter · 15th May 2004, 01:42 PM

Sorry, I forgot the Hz formula. We need to know the sprung weight of the car front and rear. Lets suggest 2600p, with a 50-50 distribution. The axle then have 1300/2=650p each wheel.
Now, this formula is in metric, so 650p*0,454=295kg.
Then we take 295/9786=0,0301451. Take the root out of 0,0301451=0,1736234.
Now we decide what Hz number we want, in this case we use 2Hz.
Then 2*0,1736234=0,3472468. Divide this by 0,159. 0,3472468/0,159=2,18
Then 2,18^2=4,77. That’s it.
We need a wheel rate of 4,77 kg/mm. Which is the same as 266p/inch. Kg/mm*0,5595=p/inch. 0,5595*4,71=266.

Goran Malmberg