Did I use a wrong formula. I convert inch to mm. Then the number × it's number 4 times

 

Sounds like you went the right direction. Take the diameter of each bar, to the fourth power, and then compare the two results.

 

Hello- Well, after a month of research on suspension upgrades I ended up talking to a tech guy named Ed at Duntov Corvettes in Texas. They RACE C-2 corvettes as well as newer ones. Asked Ed about suspension upgrade on my C-2. Ed says they installed VBP transverse spring setup on their RACE car and saw no improvement in track times over the original coil spring/shock setup. Of course their coil springs are custom made and they have tuned them to go with their 1&1/4" front swaybar. Ed said that the weight reduction is nice but hardly worth the money. As for coil overs, he said they weren't bad in front but none of the current rear coil over solutions he has seen, sharkbite, ridetech, etc., are engineered to optimize geometry and the way they are mounted, bolt on, puts too much stress on them. In other words, stay with the 7 leaf I have. Interesting Ed recommends softer front springs, like 450 lbs as their car sticks to the track better than with my 550 gymkata springs. Opposite of what I have been taught after owning 3 Corvettes! Again, these guys race corvettes and have no skin in the game for either solution. Ed said they looked at offering a transverse setup similar to VBP but decided against it because of no performance improvement, per se. My take is this: Since '84, Corvettes have been unibody and our cars HAVE FRAMES. This makes all the geometry different from the newer cars. Even C-2 guys that have bought the new $25k frames still do not have a chevrolet designed car. Ed said over 90% of a cars handling is in the frame so the way expensive frame upgrade is worth it if you have the dollars.Bottom line: I am replacing my 25 year old KYB shocks, leaving the rest alone and saving for my dream old man's car. A Cadillac CTSV!!! Good luck.

 

I am not surprised by most of this ^^^^^^^^^BUT I would say you may be missing the biggest benefit of the 360 monospring versus the 7 leaf 292lbs steel spring ...THE RIDE is so much better with the monospring coupled with Bilstein Sports in the rear and only weighs 8 lbs versus 50 lbs for the steel spring. Also, the composite will not wear out (sag over time) plus will deliver better handling on imperfect roads due to better spring reaction time than a steel spring on the street, not billet smooth race tracks.........

 

Good for you.
You did your research and based your decision on what will work best for you and your use of your car.
I'm doing some things on my 73 BB resto/mod that others balk at, but for the way I'm building my car and for my driving, I'm building it my way.
Have fun and enjoy.

 

I just replaced a full Performance Plus VB&P setup on my SWC with Ridetech's complete package. I still need to get the car aligned, mount new tires (I need more clearance up front because of Ridetech's spindles) and fine tune the shocks, but my initial reaction is WOW! The car feels so much better. I also ditched the Steeroids r&p I installed a few years ago for a Borgeson box (required for Ridetech's front suspension) and I love it. Did it cost a small fortune? Yes. Was it worth it to me? No question. It's a completely different car.

 

How about some pictures of your build ? Hope it all works to your satisfaction.

 

Yep-

 

Here's what I have said in another thread, though I've updated it slightly.


Short answer is of course "it depends".

*All things being equal*, meaning same suspension geometry, same spring rate, etc. then NO. Coil springs are not better than the transverse leaf. They also aren't worse either!

Literally all the spring is doing is providing a spring rate. Example being a spring rate of 500 lbsf/in: Whether that's in coil form or leaf form, its still 500 lbsf for every inch of displacement.

You could make a case that a composite (not steel) leaf is better than a coil spring due to lower center of gravity as well as less mass.. but you'd need the numbers to prove it. I suspect that it is the case but I don't have the numbers either! Like you mention, the engineers who design the C4/5/6/7 suspension aren't stupid and have probably thought of this.

Additionally, if its a dual mount spring that's done correctly, there's anti-roll inherently in the spring.

See the properties section of this page for what I mean: https://en.wikipedia.org/wiki/Corvette_leaf_spring

But this is nitty gritty detail stuff that probably isn't noticeable unless under repeatable/controlled conditions (such as a race track).

So, if you're literally just swapping out the factory leaf spring and damper for a coil-over spring/damper and nothing else is changing, in my opinion there's not much benefit for the added cost.

Now, here's a few caveats considering the reality of suspensions available for C3:

Adjustability: A nice benefit with coil overs is adjustability. You can change your spring/damper rate for when you're at the track, and then change it back when you're on the street. (although changing spring rate means swapping out the coil spring itself which could be a bit of a pain). The factory leaf and dampers don't have that capability. However there are aftermarket composite rear leaf setups (VBP, etc) that can adjust the spring rate fairly easily and also come with adjustable dampers. From what I have observed these are more affordable and have enough adjustability to satisfy the needs of anyone but a serious racer who needs the broader range and higher resolution of a coil over spring. Plus, I'd argue they're easier to adjust.

Geometry: Everything above this assumes suspension geometry is largely the same in these comparisons. If a coil over package manufacturer has done their homework and corrected some of the known suspension geometry issues on C2/C3 corvettes, then YES a coil over suspension is definitely better. This isn't because of the coil overs though, its because they addressed the geometry issues elsewhere in the suspension. The detroit speed rear suspension fixes this from what I've seen, but it ain't cheap. The 6-link system fixes some of the issues as well. If I understand it right the RideTech, VBP, 6 link systems all still have some of the C2/C3 issues (toe out when the rear suspension is compressed past the point of the half shaft being parallel to the ground being a big one).

That being said, I personally haven't seen any hard facts or real measurement data from any of the suspension manufacturers to back any claims up. They all claim they're the best but don't prove it.

Sorry I know it's not a clear/easy answer. If you're potentially dropping thousands of dollars on suspension I recommend doing your own research as well. Its easy to get caught up in slick marketing, people's confirmation bias for the suspension system they bought, and pretty suspension systems on internet forums. Good luck!

 

Excellent analysis of the issues and benefit or lack there of of all the different suspension options ^^^^^^^^^^^^^.

I particularly like the analysis of GM not being stupid about continuing to use the transverse leaf spring suspension not only in the rear but the front..............if it was inferior to a different superior design......no way around that fact.

 

this statement from Ed registers high on the BS meter. Real track racing vettes a good starting place spring rate is around 700 for a sbc and 500+ rear

 

I think what Ed says definitely has to be taken with a huge grain of salt since they race in SVRA Group 6 and are pretty much stuck with having to run the stock suspension setup. Anything too crazy and they get put in GTO/GT-1 class.

 

So far so good. Of course this makes the third time. I posted some pics in the C2 forum here: https://www.corvetteforum.com/forums...post1596904978

 

You beat me to it.

Run what the goodguys/LSfest guys are running. VanSteel/RideTech/Detroit Speed

 

you are actually correct. The VBP does reduce weight and probably improves ride, but I don't care about the ride. I like it firm so it handles better. That being said, Ed at Duntov Corvette, who is also a licensed engineer in the State of Texas told me the LAST PLACE A CORVETTE NEEDS TO LOSE WEIGHT IS OVER THE REAR AXLE. Again, after extensive testing on a closed track Duntov Corvette took a C-2 race car that weighs less than 2800 lbs and was not able to improve track times with VBP transverse setup and rear mono spring over the original style coils and shock setup. Their car did have their custom made 450lbs front coils, their custom shocks & 1&1/2 inch swaybar in front. Also rear sway, don't remember size but i think 1". 90% of a Corvette's handling is dictated by the frame. Stiffest frame = best handling. I don't need a new $20k frame for a car that runs mostly on the street and nostalgia drags summertime. I don't autocross anymore but in the 80's my car beat then state of the art Porsche 930 turbo cars when i had street slicks on it. Like they say, "there's as *** for every saddle".

 

I don’t race a Corvette but I would think any racer would tell you any weight loss is good weight loss for handling purposes. You can tune to a point for where the weight is distributed. I would also say the Auto cross guys are more in tune with handling than what is demanded by road racing. I certainly agree with the statement that a spring is a spring no matter what form it is in. I had the dual mono springs on mine before I decided to go with Ridetech’s rear system. I also have fully seam welded and gusseted my frame per the Chevy Powerbook. Can’t comment on it yet but the monosprings worked great on mine. Looking forward to comparing it with the Ridetech. I had my monosprings, both front and rear, on the stiffest settings and it was fine on the street.

As for Duntov, engineer or not, I would do some searching and reading before you give them one red cent of your money.

 

I would be cautious as well! ^^^^^^^^^^

If someone told me that the last place a C3 corvette needed to lose weight is over the rear end, I would be suspicious.......

Most SBC C3's have an almost ideal weight distribution of 48%F:52% rear with some years closer to 50:50 weight distribution. For road racing the slight rear bias is preferred with my race style. Now if the have a 78 C3 like mine that has a F48%:R52% weight distribution and you start lightening the front with removal of pollution control equipment like the AIR pump and hardware, AC removal, aluminum heads, removal of the heavy cast iron manifolds etc without removing some weight in the rear like the 50 lb steel leaf spring, the rear weight bias will exceed 52% which would not be ideal in general terms.
In general, any weight removal is good as 69ttop502 stated as long as you can either tune the suspension to the new settings or balance the weight reduction front to rear.

 

I think what Duntov Corvettes point was with regard to the rear spring is that in high horsepower cars less weight over the rear axle means less traction. The steel spring acts as ballast. Any one with the fiberglass rear mono spring done any amateur level or nostalgia drags? Wonder if anyone has noticed lack of ability to "hook up" using the fiberglass rear spring?

 

After a month or research on suspension upgrades I agree with you. I have seen Corvette C-6 race cars with coil over but they also look like they have tube or totally non-stock frames. Duntov Corvette told me most of the handling comes from the frame, not what kind of springs you have. They could not get a faSter lap time with transverse front rear mono on their C-2 race car than the original style coil and rear 7 leaf. I think I will try the VBP rear mono just to see how i like it since my 7 leaf big block spring is 20 years old anyway. Will post results. If I find the car won't hook up with the 50 pound loss under the rear axle i will be going back to a 7 leaf.

 

I just bought a Ridetech coilover for the rear of my 74 resto. I don't plan on racing my car. The reason I went with coilovers in the rear was basically price, materials and ease of adjustibility (ride height).

I had a broken half shaft that dented the differential support bar and cracked the composite spring. The cost of replacing the differential support bar, cracked composite spring, buying offset trailing arms, new Bilstein HDs, and strut bars was within $100 or so of a Ridetech rear end. The Ridetech system comes with its own support bar, they offer a 1,000,001 mile warranty on their shocks, they use heim joints in the trailing arms and strut rods vs rubber bushings in stock and ride height adjustments on my considerably lighter than factory car should be trivial.