C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

VBP adjustable front spring

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Old 11-07-2018, 01:15 PM
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Robert
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Default VBP adjustable front spring

Since Vette Brakes is out of business and I can't seem to find them anywhere, does anyone have the instructions for this spring? Or an installed picture?
TIA
Robert
Old 11-07-2018, 04:51 PM
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Kevova
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The spring will install like a OEM spring. The adjustable part allows the ride height and corner weights to be set. You need scales and a tape measure to take advantage of the adjustability feature. The spring rate will be high on this spring the adjustability does not reduce the spring rate. Spring is designed for competition.
Old 11-08-2018, 08:45 AM
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MatthewMiller
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Kevova is correct. However, here are the official VBP instructions:

Kit Contains:
ITEM # QTY DESCRIPTION
1 - 1 Front Fiberglass Monoleaf Spring
2 - 2 Polyurethane End Pads (attached to spring)
3 - 2 Polyurethane Frame Mount Pads (each set contains 3 pieces)

Vehicle Lifting.
1. Lift car on hoist or place on jack stands. Car chassis must be at least 18” off ground. Caution: Jack car only
on level surfaces.
2. If using jack stands, place stands under front of frame at the spot where the frame begins to run parallel with the
edge of car, where frame is flat. In rear, place stands at corner of frame, just behind door. Use jack stands
only. Do not use concrete or wooden blocks. Push on car to make sure it’s secure on jack stands.

Front End Parts Removal. Do One Side At A Time.
1. Remove front wheel. Leave brake caliper in place.
2. Place jack underneath lower control arm’s outer end, close to the ball joint. Caution: Do not damage zerk
fitting. Fully extend jack. Put enough pressure on jack so it supports the lower control arm. (A block of wood
between jack and control arm may help).
3. Remove shock absorber mounting bracket, leaving shocks attached. Disconnect sway bar end link, but leave
sway bar in place. Remove cotter pin from lower ball joint.

Lower Control Arms.
1. Loosen each bolt on the lower control arm (at end of bushings). This will allow for easier turning of control
arms.
2. Raise control arm assembly at least one inch as a check so that all control arm weight is on jack. (But don’t lift
car off jack stands).
3. Using a ball joint disconnector tool, loosen ball joint so that spindle assembly drops. Remove ball joint nut.
4. Push spindle assembly (hub, rotor, and brake caliper) out away from control arm assembly a few inches and
support spindle on jack stand. Caution: Do not damage brake line or leave spindle hanging by the brake
line.
5. Remove plate protector by loosening four bolts attached to frame.
Note: Use extreme caution in the next few steps!
6. Slowly drop jack that is underneath the lower control arm. This releases the residual spring tension. Because
this pressure is large on stock springs, use extreme caution. Make sure the jack doesn’t slip out ... stand in
front of the car, out of the way!
7. Swing lower control arm to downward position. Leave bolts in place.
8. Repeat procedure on other side of car.

INSTALLATION INSTRUCTIONS
FRONT MONOLEAF SPRING KIT
31302/31332 1984-96 CORVETTE

Stock Monoleaf Spring Removal.
1. Remove two 15mm nuts on both sides that hold spring centermount bracket in place (Retain nuts for installation
of replacement spring). This will drop spring into frame cage.
Note: Removal of stock spring requires added clearance with hoist or jack.
2. Remove spring from driver’s side of car.
3. Remove All Factory shims as this may make the car ride high

Installation of Replacement Monoleaf Spring. Do one side at a time.
1. Align the spring ends to the lower control arms using the ball joint as a reference. At this time, align
polyurethane centermount pads with the bolts for the centermount bracket. If needed, jack control arm up so
enough thread is available for attaching nut.
2. Bolt spring centermount brackets to top of frame cage using original bolts. Make sure polyurethane pad on
centermount bracket faces down.
3. Repeat procedure on other side of car.

Lower Front Ends Parts.
1. Tighten control arm onto frame. Use original 15mm nuts.
2. Install ball joint into spindle assembly. Install castle nut onto ball joint stud.
3. Tighten bolts and nuts using proper torque values (ft/lbs):
Lower Control Arm to Lower Ball Joint 48
Spring Protector to Crossmember 18
Spring Retainer 20
Shock Absorber Bracket to Lower Control Arm 22
Sway Bar End Link 35
4. Align castle nut with hole in ball joint stud for proper cotter pin installation. Reinsert cotter pin.
5. Repeat procedure on other side of car.

Upper Front End Parts.
1. Reinstall shock mount bracket.
2. Torque bolts to 22 ft/lbs.
3. Reconnect sway bar end links.
4. Lubricate grease fittings on ball joints.
5. Reinstall wheels.
6. Take car off jack stands and lower to ground.
7. With the weight of the car on the wheels, Loosen and retighten the lower control arm bushings.
Caution ... To ensure longevity of your spring:
Do not strike spring with hammer or other heavy tools.
Do not attach tow chain or trailer tie-down to spring.
Do not expose spring to torch or excessive
Old 11-09-2018, 09:06 AM
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Robert
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Thanks for your replies but I should have asked what are the adjustment instructions. I can see the ends (on the A-arms) can be adjusted but why are there shims for the cradle? Is it because you could run out of adjustment on the "ends"?
I should add that the car came with the spring which I was told was added stickly for ride height.
Thanks again
Robert
Old 11-09-2018, 09:16 AM
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MatthewMiller
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Originally Posted by Robert
Thanks for your replies but I should have asked what are the adjustment instructions. I can see the ends (on the A-arms) can be adjusted but why are there shims for the cradle? Is it because you could run out of adjustment on the "ends"?
I don't think there should be any shims remaining on the cradle. The factory shims should have been removed for this spring, and there should only be the VBP poly pads in there. Those pads need to be there to keep the metal clamps from directly contacting the fiberglass spring, which would eventually wear into it and compromise it. They are also sized to create the proper stack height in the clamps. But again, per the instructions above there should be no other shims in there. To adjust the ride height (or corner weights), you put a wrench on each end bolt (jack screw) and turn the bolt to raise or lower the pad that contacts the A-arm.
Old 11-09-2018, 10:00 AM
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Thanks Matt. I saw that the parts list above doesn't mention any metal shims but I was given a bag with 2 aluminum shims, maybe 3/16" thick. Was told "i probably won't need these", maybe these are the original GM and not VBP? But they looked too nice to be GM. The guy that installed the spring has done so many other things incorrectly that it has made me question all of his work. Thanks for your time.
Old 11-09-2018, 10:06 AM
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MatthewMiller
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Originally Posted by Robert
Thanks Matt. I saw that the parts list above doesn't mention any metal shims but I was given a bag with 2 aluminum shims, maybe 3/16" thick. Was told "i probably won't need these", maybe these are the original GM and not VBP? But they looked too nice to be GM. The guy that installed the spring has done so many other things incorrectly that it has made me question all of his work. Thanks for your time.
Yep, I think those are most likely OE shims or some other company's aftermarket version of them. The VBP springs don't come with those and shouldn't use them.

BTW, you noted that the spring was installed strictly for ride height. But note that this is a much stiffer spring than most stock C4 springs. Each one came out of the mold with slightly different rates. VBP would test each one and write the measured rate on the spring in yellow paint pen. For example, mine measured 1125lb./in. Yours is probably in that range, give or take 100lb/in. I don't consider this to be a bad thing - it will handle better and grip better than a softly sprung stock C4, at the expense of some ride comfort. I'd be curious what your rear spring is, too.
Old 11-09-2018, 12:27 PM
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Robert
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Matt, I found the sales receipt, front is VBP#88300 and rear is VBP#31301. I have no idea what the rate either has. Not sure that info would help you because my application isn't a C4. I stuck C4 front cradle and C4 rear 'batwing' on a C1 frame. With the stock springs it looked like a 4x4 and 3 years ago VBP was making spring rates for this application so hopefully the ride won't be too jarring.

It seems I also purchased two VBP#P1-400 "TVL-RDM Style Isolators (4)" Do you have any idea what these are? Possibly what I called shims earlier??? Should have taken a picture but they are about 2' wide, 5" long and 3/16" thick. Maybe for the rear spring???

Again thanks for you replies
Old 11-09-2018, 01:31 PM
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MatthewMiller
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Originally Posted by Robert
Matt, I found the sales receipt, front is VBP#88300 and rear is VBP#31301. I have no idea what the rate either has.
That rear part # is definitely for a rear C4 spring. I am not sure what rate it would be. You can probably see the actual, measured rate written on the spring if you get under the car and check it. It will probably have "K" and then then a 3-digit number, and the number is the rate in lb/in. That front spring part #, I am not sure about.

It seems I also purchased two VBP#P1-400 "TVL-RDM Style Isolators (4)" Do you have any idea what these are? Possibly what I called shims earlier??? Should have taken a picture but they are about 2' wide, 5" long and 3/16" thick. Maybe for the rear spring???
Maybe - I'm not sure. TVL and RDM are two styles of VBP springs, but I don't know what styles. It may be two replacement poly isolator pads, or it may pertain to those shims. I'm just not sure.
Old 11-09-2018, 01:40 PM
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Appreciate your efforts.
Old 11-09-2018, 03:29 PM
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Kevova
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A with a C1 being not very heavy it maybe worthwhile to consider coil overs. Ride is going to beyond harsh with those springs.
Old 11-09-2018, 04:40 PM
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Ya maybe but I'll have to get it on the road first and find that out. Started this project some 20 years ago (life happens!)
Thanks
Old 11-13-2018, 08:51 AM
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PM inbound.
Old 11-13-2018, 09:16 AM
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Originally Posted by Kevova
A with a C1 being not very heavy it maybe worthwhile to consider coil overs. Ride is going to beyond harsh with those springs.
Coilovers or springs is not really the issue with vehicle weight. There are much lower-rate monoleafs available, too. If the OP finds the ride too harsh, he can always just swap in OE springs from a later-year base C4, which are less than half the rate of the VBP Xtreme springs. And of course there are other OE springs in between those...ahem...extremes.
Old 11-13-2018, 09:29 AM
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Looked for the spring rate but with it installed couldn't find anything
Thanks to all
Robert
Old 11-13-2018, 09:30 AM
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With the project started 20 years ago it might be important to mention which suspension components you used for the front. The 88300 number is for I believe an '88+ front and if you've 87 and earlier suspension you may need to rethink all of it. Which suspension do you have on your project? The rears are all C4 - the front is more application specific.

This could be used as reference material 'maybe'!!

https://www.corvetteforum.com/forums...post1581903383

Last edited by WVZR-1; 11-13-2018 at 09:35 AM.
Old 11-13-2018, 09:42 AM
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front was out of a 94, rear is a Dana44 from a 93. Seem to recall talking to Gary from VBP and I think the front spring rate is much lower than normal because of this application, I'll be sure and jot it down if I happen to be able to see the markings.
originally I put in a 95 Corvette LT1 and Camaro T56 put recently changed to a LS3 and T56.
Almost ready to block the primer for paint so I can see a finish line even if its still a year out

Thanks all

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Old 11-13-2018, 10:12 AM
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Originally Posted by Robert
front was out of a 94, rear is a Dana44 from a 93. Seem to recall talking to Gary from VBP and I think the front spring rate is much lower than normal because of this application, I'll be sure and jot it down if I happen to be able to see the markings.
originally I put in a 95 Corvette LT1 and Camaro T56 put recently changed to a LS3 and T56.
Almost ready to block the primer for paint so I can see a finish line even if its still a year out

Thanks all
88300 search in the C4 section should get you interesting results, seems very likely to be 1000 to 1200 and the actual likely on the invoice as well as tire crayon on the spring. It's correct for your install You might reach out to this OP - he was always very good about posting very good information regarding projects. He could likely identify correctly your accessories.

https://www.corvetteforum.com/forums...hocks-etc.html
Old 11-13-2018, 10:23 AM
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Originally Posted by Robert
Looked for the spring rate but with it installed couldn't find anything
Thanks to all
Robert
Just to make sure you know what to look for, in the pics on that "for sale" thread that WVZR-1 linked the tested spring rate is the "K=1010" on the top side of the spring. So that spring in the pic has an actual rate of 1010lb/in. This was written with a paint pen, so it's usually pretty durable. You should probably be able to see it looking down at the spring from above (if your spring is installed), near one of the two ends.
Old 11-27-2018, 08:55 AM
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kellsdad
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This is just a curiosity questiion for any who know the answer. If a monospring is rated at 1000 lb/in, does that mean each end of the spring (i.e., half the spring) is acting at 1000 lb/in, or does it mean a combined weight of 1000 lbs pressing down on the center of the spring will deflect both ends of the spring up one inch?


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