Chrysler Composite Monoleaf - Big weight savings

[wantone]

I see, I'm a guinea pig! A lab rat!  lol

let's not put TOO fine a point on it but 

[cudabob496]

OK, spoke with Hyperco engineer Mark Campbell, 574-753-6721. Asked him what spring rate
I would I need to use their composite leafs.  He needed weight of my car, 3300, wieght distribution, I guesses 55/45, type of rear end,
and rear wheel and tire size.  He took 45% of 3300, subtracted the unsprung weight of the rear end,
which he said was about 340 lbs, came up with about 1100, or 550 per rear wheel, and said 175 spring rate
should work.  But he said it might sit a little low, so 200 would be best to assure the rear would be at stock height.
Wondering if I should go to 225 spring rate to make sure. Don't know how much higher car would sit, if I did.
Will probably call him again about that. I have a few more questions to ask.

[Mopar Mitch]

I've tried 3-4 different sets of leafs in the past... ended up with FLEX-A-FORM fiberglass mono leafs... they make the GM 'Vette fiberglass leafs.   I went with these due to their light-weight (saved ~25+lbs per side).    A critical point you have to decide upon is the arch per pounds.   A higher arch will have the wrong effect for improved handling... as the car sits at rest.   A flatter arch, at rest, helps in the handling.... keeping the car (rear-end) flatter in the turns.    After talking with a FLEX-A-FORM engineer many years go (mid-1980s), we decided  upon 225# with a 5" uncompressed arch... settled/weighed down, in race-trim for AX competition, there was only about 1-1.5" of uncompressed arch... AND... the fiberglass springs do need time (~15-30 days) to settle after initial installation.   Having adjustable shocks, mine are red Konis from the past, but I'd get 2x adjustables someday in the near future).. will help tremendously to better fine-tune your ride/handling.   I'm very pleased with my overall suspension setup... the fiberglass mono-leafs definitely contributed to the overall package (reducing weight and improved handling).    IF I'd replace these leafs again, I would consider 250#/4" uncompressed arch.... again in light-weight mono-fiberglass.   I'm aware of certain top-level SCCA AX drivers/cars running these with better satisfaction than their previous lighter-stiffness leafs.

Caution/beware:  IF you drive lots on the street, and over rough roads, you will notice a harsher ride in the rear.   Stiffer leafs/suspension give better handling on smoother roads;   rough roads can favor a  little softer suspension.... be willing to try different setups... adjustable shocks (2x preferred) can take away some of that testing time. 

[cudabob496]

I've tried 3-4 different sets of leafs in the past... ended up with FLEX-A-FORM fiberglass mono leafs... they make the GM 'Vette fiberglass leafs.   I went with these due to their light-weight (saved ~25+lbs per side).    A critical point you have to decide upon is the arch per pounds.   A higher arch will have the wrong effect for improved handling... as the car sits at rest.   A flatter arch, at rest, helps in the handling.... keeping the car (rear-end) flatter in the turns.    After talking with a FLEX-A-FORM engineer many years go (mid-1980s), we decided  upon 225# with a 5" uncompressed arch... settled/weighed down, in race-trim for AX competition, there was only about 1-1.5" of uncompressed arch... AND... the fiberglass springs do need time (~15-30 days) to settle after initial installation.   Having adjustable shocks, mine are red Konis from the past, but I'd get 2x adjustables someday in the near future).. will help tremendously to better fine-tune your ride/handling.   I'm very pleased with my overall suspension setup... the fiberglass mono-leafs definitely contributed to the overall package (reducing weight and improved handling).    IF I'd replace these leafs again, I would consider 250#/4" uncompressed arch.... again in light-weight mono-fiberglass.   I'm aware of certain top-level SCCA AX drivers/cars running these with better satisfaction than their previous lighter-stiffness leafs.

Caution/beware:  IF you drive lots on the street, and over rough roads, you will notice a harsher ride in the rear.   Stiffer leafs/suspension give better handling on smoother roads;   rough roads can favor a  little softer suspension.... be willing to try different setups... adjustable shocks (2x preferred) can take away some of that testing time.

thanks, any experience with the Hypercos. Seems like a potential 100 lb savings?

[HP2]

Changing to a mono-leaf suspension and doing drag race style starts with high loading will necessitate adding a traction device, like Cal-Tracs or Slide-a-link, to avoid spring wrap with good traction. Make sure you make the tech rep aware of your intended usage and get their recommendations for traction devices.

Net savings may be closer to 60-70 pounds overall, possibly less depending on the traction aid utilized.

[Mopar Mitch]

CudaBob -- Aside from factory-style metal leafs (HD and de-arched SS springs), I only have experience with the fiberglass Flex-A-Form leafs as that company was THE primary choice back in the '80s-90s for top-level national competitive SCCA autocrossers -- again, they make the f'glass springs for the GM Vettes; lots of guys running their GM F-bodies ran Flex-A-Form, same for some early Ford Mustangs.  Hyperco and ESPO were not in the scene for the serious autocrossers at that time.

[cudabob496]

thanks, I was hoping my adjustable pinion snubber would be sufficient, as it is not
with the stock heavy duty leafs.
May rethink this whole thing if I gotta buy Cal-Tracs too.
I just ride on street, with the occasionaly stop light theatrics.

[jhaag]

wasting your money. Your car will not be any faster from stoplight to stoplight over 50lbs. If you are spinning your tires at all now, you would be better served to increase traction rather than spending money to save a few pounds. 

[HP2]

The old convention was .1 second e.t. reduction for every 100* of weight loss. So 50# would be worth .05 second, if your hooking up, over a quarter mile. Slightly less in the 1/8 and even less in a city block.

Funny thing about the Calvert suspension system is it was designed by a Ford racer who, due to rules limitations, couldn't alter his suspension pick up points, so he created the Cal-Trak and mono-leaf set up to emulate the Chrysler SS spring action in his Mustang to gain a traction advantage over the stock Ford spring design.  Cal-Traks create a dynamic shortening of the front spring segment to make it perform more like a rigid bar instead of a spring. This is the same principle behind the Mopar asymetrical design and the SS spring pack in particular.

There are still some tricks in hooking up those mopar leafs if you dig into them. You can try removing some clamps in the rear segment and adding clamps in the front segment to replicate the SS action. Beyond that you will need to either replace them or get into leaf pack surgery, but they can be improved further.

[EB3-GranCoupe]

More stuff to watch, listen, and learn....

 

[cudabob496]

Starting to look more involed than just slapping on a pair of lightweight leafs.
The installation at Hyperco.com does not look simple either.