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Purchased a project car several years ago. Came with the VBP dual mount set up and spring. Installed both, but now seeing pics that don’t look right.
Spring I mounted says “RDM” and also “331 – K=280.” Maybe RDM means rear dual mount?
The problem is every pic I see of other dual mount set ups has a flatter, thinner spring between the mounts and thicker ends. My spring is rounded and thicker in the middle, and thinner on the sides. Worried if the mounted spring from the PO was designed for center mount, would there be problems in ride and/or strength, especially at the ends.
This first picture is my setup. When on ground, the spring is flat between the mounts and bends upward on the sides.
Here are a few pictures found online of the same system. Definitely a flatter (even concave) and thinner section between the mounts, and much thicker at the sides.
That just seems all sorts of "wrong". I can't imagine designing in a double reverse flex like that. you'd think they'd at least put some sort of support to the diff to keep the proper curve through out.
Ever time I hit a dip I'd be waiting for a sickening crack sound!
Originally Posted by kodpkd
Wow,,, that's a long way to go just for a spring. Does it have a progressive rate?
Thanks for the comments everyone, but mystery solved.
Just spoke to Dan at Vansteel and he confirmed that RDM does mean "rear dual mount." So, even though my spring looks different than the other pics, and is very thin (5/16") at the trailing arm bolts, I don't have to worry about losing it on the freeway because the previous owner messed up his order.
Good to hear. Dual mount does give you better handling and doesn’t affect the duty cycle of the spring. Later generations of Corvettes went with dual mount. Here’s a wiki I found that you might find interesting.
Good to hear. Dual mount does give you better handling and doesn’t affect the duty cycle of the spring. Later generations of Corvettes went with dual mount. Here’s a wiki I found that you might find interesting.
Thanks. Found this, and couple of weeks ago took off the 7/8" rear sway bar and put back on the stock rear, which I believe is 5/8" . Had been chasing ride quality for a while, and so the rear dual mount (in the softest setting) with the thinner sway bar, and adjustable QA1s (also pretty soft setting) with 550 coils up front did the trick. Very good cruising ride quality but still handles well in corners.
This is an older install of a VBP rear spring on my 69, I installed it about 20 or so years ago - certainly not as clean and shiny as yours! I guess my car is more like that cheerleader from high school, pretty on the outside but kind of a mess underneath? These photos show the missing spring clamp cushions on the passenger's side.
I don't have any photos of the spring with the weight of the car on it (sitting on the ground), I will see if I can go grab one.
Call VanSteel, they have the rights (I believe) to the old VBP stuff and helped me out with a few missing bushings (flat cushions) which turned out to be pretty important.
ps. I added a photo of my 69, not that it will help answer your question, I just like looking at it - But really, give Van Steel a call 800-418-5397 They are in Florida.
I would love to test drive this spring. It seems that it would corner very well. As the car corners the opposite side wheel squats a bid which would lower the rear and keep the car flat, when cornering. Cool.
I can testify that this spring arrangement is similar to the C4 spring and works very well for a weekend play toy, as long as you don't want really high spring rates. I have them paired with (now obsolete) Edelbrock shocks, along with a lot of other tweaks to the suspension geometry like a modified camber curve, bumpsteer, ackerman angle, etc.
The dual mount spring been on the car for over 20 years with no problems.
So the early VB&P Duel Mount Springs were thicker in the center and always maintained an arch shape. Then towards the end they came out with what I call the " Gull Wing " style. Not really sure what the advantage was or why they changed the design. However both of my " Gull Wings" failed almost intstantly.
OP here. Lost track of the thread and just saw your post Gale Banks 80. This helps answer my question, as I clearly do have the thicker in the middle, thinner at the ends version, which must've been the early version you mention. About 500 miles and so far so good. But glad the previous owner didn't make a mistake in spring selection, as the gull wing style look significantly different than mine.
The early style which I believe was the majority of the ones made will last forever as there are ones out there 30 plus years old. My first Gull Wing Spring broke 50ft out of my shop. The second one I trailered the Car to a chassis Dyno and it broke there. When VB&P made them they were made 3 at a time in a mold. Then they were run threw a Table Saw and cut into 3. I probably bought my first spring ( not a duel mount ) from them ib 1983 or 4 and I still have it.
Wrong Spring for Dual Mount Rear Mono Leaf??
