Hello, Does anyone know of a recommended rear shock to use with a rear composite mono spring. My "standard" shocks give a very jumpy ride. Thanks, Frank. Hope you all had a great Thanksgiving.

 

Frank

I have emailed VPB and quizzed them on bouncy ride & spring rates with these monosprings. I have been wrestling with this problem for some time now. I have received a couple of fairly comprehensive replies from Gary at VPB. He has offered me some composite springs that have tested out at less than 300lb. They have some that have tested down to about 250 lb. I will probably order the lower rate spring in the near future.

I have since learnt that the standard springs are around 190 - 200 lbs/inch. For some reason the monosprings are built with a rating alot stiffer than standard which starts at 300 lbs/inch ???. I believe the main problem here is the huge increased stiffness of the monospring requires a correspondingly massive increase in shock rate to try and control the thing. And you just a'int going to get a good ride.

The first shocks I had on car with the monospring were new standard KYB's. Pretty bouncy !!
I bought some of the specially valved KYB's from VBP earlier this year, hoping to remove some of the bounce. The rebound still seemed quite severe to me and car was still quite lively at the back. KYB's are probably valved more for roads in the US and I'm picking your road surfaces are a lot better than here. Driving the car on the motorway is fine but as soon as start hitting hollows and bumps in the road I have to hang on!!!
In desperation, as a third attempt, I ordered some adjustable QA1 shocks from Summit
(Stocker Star AL Rear Shock TC1574P )
http://www.summitracing.com/parts/HAL-TC1574P
I started at the No1 setting and worked my way up. The No5 setting seems to control the rebound a lot better, but being a racing type shock there damping is quite stiff and I cannot adjust damping individually for bounce (up stroke). As I go up the number scale on the shock settings, the bounce seems to stiffen up as well, which seems to have the effect of making the apparent spring rate increase even more than it already is - well it feels like that through the seat of my pants !!!

The next step is either go for the 2 way adjustable QA1's to be able to dial in more rebound dampening (very expensive) or try a low test rate monospring (250lb/inch).
VPB have even offered to exchange my 300lb spring for a small restocking charge. While it is a nice gesture, the shipping charges to send it back 10,000 kms from here, kind of kill that idea. Just thought I should give them a little plug for trying to be helpful.

Neville

 

Nev is right on. I started with a VB&P 360#, then exchanged it for a 330# and it made no real difference. I also went through about $500 worth of rear shocks trying the Bilstein Sports, Bilstein HD, KYB GR-2, and now have the QA-1 12 way adjustable. Still hate the ride. Too much bounce. I will be going back to a 9 leaf or check on Air-ride air bags.

 

Hey Ken, hope you had a good Thanksgiving.

What setting did you wind up with on the QA-1's?

 

I started with VBP 330# spring and Bilstein sport shocks. Too stiff and too bouncy for me. VBP suggested a lighter spring. I swapped out for a 300#, actually a 285#. VBP did the swap for shipping only. Very nice of them. Still too stiff for me. Sold the Bilsteins and changed over to adjustable Konis. I don't remember the setting but much better. I came across a deal on some Spax externally adjustable shocks. Sold the Konis and put on the Spax. I like it now. A set of 17" wheels and tires improved the ride quality even more.

I guess I should add I have shortened 460# front springs, 1 1/8 front sway bar and removed the rear sway bar.

 

Dave,

I started at #6, then went to #8, then to #4, and back to #6. I might go back to #8 as the stiffer ride is better than the bouncy ride. I have a friend that has a small hot rod shop and he is installing air bags on my Silverado pickup. He has seen my Corvette and wants to do it also. But I am a little hesitant to change the factory look. So I might go back to the 9 leaf setup. Probably Eaton as they seem to be the choice of what I have read on the forum.

Hope you had a great Turkey day also!

 

I really wanted to use the coilover setup in mine, but the so-called bolt-on setup I bought will not work. The coils rubbed on the side of the tub. Never buy from that outfit again. I switched over to the comp. leaf, and used the QA-1 from the coilover setup. We'll see how it goes.

 

VPB (and others) sell one type of composite spring and Muskegon Brake (and others) sell a different one based on a TRW design. You usually don't see people that own the TRW designed spring complaining about a bouncy ride (myself included).

larry

 

You are right, I have heard very little from those who own the Muskegon. Not sure if that is a good thing or bad or just not many out there? I know the new vettes have the composite spring. Wonder why they ride so nice? I am not saying the VB&P is a bad spring, just for me, I don't like the ride and I have spent a lot of money trying to fix the bouncing.

 

Thanks for all the inputs. I have been experimenting with different ride heights with the 300 Lb mono spring and have now shortened the outer bolt length by about 2". The ride is stiff but not that "launching" and major jumping. The rear height is quite high and I'll try for a happy medium. Also I used air shocks to get height for tire clearance but let the air out now. Will get some good gas shocks. Been told the AC Delco gas shock is OK??
Thanks, Frank.

 

Ken,
I think the quality of the ride may have more to do with the spring rate than anything else.
I'd bet that the factory std composite spring is nowhere near 300lb.
There was a discussion about monosprings on the C3 forum a few months back check out thread below
http://forums.corvetteforum.com/c3-t...pring-zip.html
I appears as thought there is another manufacturer Hyperco. Someone from Van Steel talked about them on above thread.
"Both are good springs w/2 different concepts and 2 different types of fiberglass. VBP uses a low arch high rate vs the Hyperco which uses a higher arch lower rate spring. The Hyperco Easy Ride spring has a spring rate of 200#'s. Close to what the 9 leaf is rated at. Same mold design as OE as well."
Here is the link to Hyperco spring on Van Steels site
http://www.vansteel.com/index.cfm?fu...&SubGroup=1955
Link to Hyperco site
http://www.hypercoils.com/Products/H...f-Springs.aspx
and their brochure
http://www.hypercoils.com/PDF/brochure.pdf
Hyperco apparently make a C3 lower rate spring @ 200lb. Should work in a C2 ??
Could be worth checking out.

 

Why is this issue so hard to fix? It would seem since we all have the same design car, there would be a solution that works, without all of the trial and error.

I've got the VBP performance plus setup on my car. The rear has a 300# spring and I too have the terrible bounce issue. Since this is my first mid-year (and the only one I've ever road in), I don't know if my ride is considered good or bad. I know the card handles great, but the ride is rough.

I've got koni adjustables on front and delco gas on back.

I too worked with Gary (good guy) at VBP last year and he swapped out my rear spring and it made some small improvements. Now I'm thinking I need to go after shocks, but I too don't know which ones to go after.

I'm also wondering if I just shouldn't just go after coil overs, but then again that can be a crapshoot too.

I wish someone could just say, "THIS IS THE SET-UP YOU NEED, AND IT WONT GET BETTER THAN THIS, SO ACCEPT IT AS IT IS".

 

From the archives both Duke & JohnZ say that by using a stiffer rear spring that you must also use a matching shock system to minimize bounce and match the front spring rate w. the rear rate .

Doubling the rear spring rate with the seven leaf spring without a similar increase in front roll stiffness via increased spring rate or a bigger anti-roll bar would bias the chassis toward oversteer, and they are alreade "scary neutral" at the limit with the base spring and bar setup, but I have no doubt that typical owners who have absolutely zero vehicle dynamics knowledge would do such a bone-headed modification. Same applies to dealer service personnel. If an owner requested installation of a HD rear spring on a base suspension car, they would probably comply as they don't know any better.
Duke

The fiberglass monosprings have no interleaf friction to help damp their movement, and require shocks specifically valved for higher rebound rates to reduce/eliminate the "bouncy-bouncy" syndrome. Vette Brakes & Products has several types of shocks specifically valved for this application.

JohnZ

 

I don't totally disagree with the JohnZ quote. It may be better with the VB&P special valved shocks (which I have tried both their Bilstein and KYB specially valved) but it does not eliminate the bouncy-bouncy feeling. Especially on a 330# spring. It seems the shocks are doing all the work and the spring, very little.

 

Previously I ran a VBP #300 rear spring with stock replacement GM gas shocks in a 78 model Corvette. Was a little bouncy but not too bad.

Currently I run a VBP #330 rear spring with SPAX shocks (same shocks as SKY 65) in a 63 coupe. It took me about 15 minutes of driving to realize I needed an adjustment on the shocks. The adjustment took me another 15 minutes and the bounce is gone. Drove the car from VA Beach to Carlisle and back on various highways and back roads. Handles well, doesn't bounce and rides pretty darned well.

Rich

 

I think the questions on composite spring rates advances a discussion that has been stalled for some time. I regularly nail my head on the conv. top frame of my '65 when going over a dip and say "please give me some rebound damping!". The big monospring on my '99 is well controlled with a "modern shock". What is the spring rate on a C5? Who makes a shock with rebound damping adjustment totally independent of compression damping?

Andy

 

QA1 - but they are expensive !!!

 

I have the QA1 12 way adjustable and it helps but not enough in my opinion.

 

The expensive ones I was thinking of were the DTC1574P double adjustables $300+ !!! each
http://www.summitracing.com/parts/HAL-DTC1574P/
(from the blurb "Double adjustable valving for 576 possible choices")
I have the TC1574P Single adjustable 12 way about $139 from Summit.

 

I have the single 12 way also. I don't see a need to spend double the money to get more than 12 adjustments? I tried the Bilstein sports that have the high rebound, and the Bilstein HD with softer. Also the specially valved KYB from VB&P which none of them worked but all advertised as the fix for a composite spring. I really think it's the spring no matter what you use for shocks.