57 Nomad

West Virginia

55 Nomad


55 Chevy Sedan



FOrt Collins, Colorado
Conversion frames for Tri5 Chevys

Do you want to make your Tri-5 Chevy drive and handle like a Corvette?  At CLASSIC EDGE Designs we have developed a Tri-5 frame conversion that will bring your suspension technology forward nearly 40 years!  Conversions are based on C4 Corvette (1984-1996) suspensions, and are available for any model 55-57 passenger car except Corvettes.  Whether you have a sedan, hardtop, 2-door, 4-door, wagon, Nomad, or convertible, we can build a conversion frame for you.  We would also be interested in working with you on development of C4 conversions for other vehicles.

A C4 Corvette suspension conversion of your Tri-5 chassis provides virtually all-aluminum suspension components, modern high-performance suspension geometry, quick ratio rack and pinion steering, large diameter 4-wheel disc brakes with lightweight aluminum calipers, swaybars front and rear, a limited slip differential, and readily available suspension repair parts.  Replacement of your heavy stock steel components will reduce the weight of your car by about 150-200 pounds, and will improve handling performance tremendously.  You can supply your own suspensions, or we usually have several in stock that we can sell you for a reasonable price.  Our conversion chassis can be used with the stock C4 composite springs or coilover shocks for maximum flexibility.

Our objective is to make a high performance chassis affordable to the "average Joe" garage hobbyist while providing a well-engineered, solid, quality foundation for your car.  Many classic frames are still in excellent shape and can be converted for much less cost than buying an all-new chassis.

We offer two versions of conversion frames (or anything in-between), depending on how much work you want to do yourself.

BASIC C4 Conversion Frames

The "BASIC" conversion frame consists of new 11 gauge (.120") steel frame rails from the firewall forward.  New fabricated front frame horns are shaped to resemble the stock profile, and include six threaded bushings for bumper attachment.  A radiator support is provided in the stock location, a frame horn spreader bar is added, and the C4 engine cradle, or "k-member" is fully integrated and welded into the frame.  All structural reinforcements are included and the frame is fully welded.  The frame-to-clip joint is reinforced with four 1/8" thick steel plates plug-welded to the INSIDE of the frame rails for a smooth, clean look.  The frame and the front clip are sculpted together so the clip appears as part of the original frame.  The C4 engine mounts are left on the K-member, and the stock Tri5 frame brackets are left on the frame.  Basic attachment brackets are provided in the rear for the C4 "batwing" (differential cover), C4 dogbones (4-link bars) as well as a basic shock crossmember and dogbone retainer plates.  This product is designed to meet the needs of the builder who wants a solid foundation, but wants to customize the rest of the frame or fabricate his own parts to save money.  Standard suspension drop is 3" in front, 2" in the rear for most combinations.

BASIC Conversion Price - $4295 using YOUR frame and YOUR C4 K-member. (see notes below)

FULL C4 Conversion Frames

The "FULL" conversion starts with the "BASIC" conversion as a foundation.  To this we add front and rear upper shock mounts, lower rear shock mounts, front and rear swaybar mounts, front brake line tabs, rear axle bumper brackets, a rear pinion support, and we remove the C4 engine mounts from the cradle. Then we add engine mounts of your choice (SBC, BBC, LS).  We also strip the frame of unnecessary stock Tri-5 bracketry.  We supply transmission crossmember brackets, but the crossmember itself is not included in the frame conversion price.  A custom tubular transmission crossmember is available.

FULL Conversion Price - $6295 using YOUR frame and YOUR C4 K-member (see notes below)

We also build front-only or rear-only conversions ("basic" or "full"), so you can use whatever suspension you want on the other end.  Call or e-mail for price.


* Frames are available for $575 for 2-piece, and $1075 for seamless (if available).  Any major frame damage is repaired.

* Suspensions are available for $975 each, front or rear (Dana 36 rear) either early or late vintage C4 (includes k-member)

* Add $1100 for early (85-88) Dana 44 HD differential, $1250 for late (89-96) Dana 44, $1350 for '89-'96 differential in early suspension.

* All suspensions are used, salvage parts but should be straight.  No refurbishing is done and some rebuilding may be required.

* K-members (engine cradles) available for $375 additional but are included with all front suspensions.

* Late ('88-96) front suspension with 2" suspension drop is $350 additional (standard front drop is 3")

* Early ('84-87) front suspension with 2" or 3" drop is $350 additional (2" front drop with early susp. not recommended for seamless frames).

* Early FULL front suspension conversions for coilovers, $275 additional (includes lower front shock mount, swaybar relocation bracket).

* Custom tubular transmission crossmember $265.

* AME frame center section kit installed with openings for up to 3" exhaust $2250

* LS engine install kit $240, SBC/BBC urethane engine mounts $110, pinion support urethane bushing/sleeve $25.

* Rear grade 8 bolt/washer/nut kits available, $125.

* No other parts provided.

* Prices are for pickup at CLASSIC EDGE Designs, palletizing and freight extra.