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Vorshlag Spherical Rear Shock Mounts (C5/C6)


Vorshlag Spherical Rear Shock Mounts for the Corvette C5 and C6 chassis

We designed and built our first prototype set of spherical upper shock mounts for the C5/C5 chassis back in 2009 (for an AST coilover install), then revised the design in 2015 and made our production versions CNC machined in-house.

Why not use rubber? Well the factory rubber upper shock mounts for the C5/C6 chassis are just a big sloppy rubber sandwich bushing. Even when new, rubber shock bushings have to compress and will "slow down" damper reactions to vertical inputs in the suspension. We want the damper to react quickly, not slowly. Rubber also wears out over time, which can create a "thunk" noise. Most aftermarket shocks will require drilling out the OEM 10mm rubber shock mount to fit more common 12mm or 14mm Motorsport shock stems.

In stock form the C5 and C6 Corvette have a (rather soft) transverse spring mounted away from the shock's load path. Of course we want to remove the horse-and-buggy style spring and convert to a coilover shock / spring layout when possible - for many reasons. This conversion moves the main suspension load path from the transverse spring into the damper and these mounts. A metal spherical bearing is much stronger than rubber - so it becomes even more important to convert to spherical shock mounts when you add coilovers.

We have made thousands of spherical shock mounts since 2008, for a variety of chassis. Our aluminum designs feature a massive spherical bearing, are anodized red, and they are strong as a tank. These have been machined in-house here at Vorshlag on our CNC machines starting in June 2015. We start with a big hunk of billet (see above left) and after two steps on the CNC lathe and a final step on the CNC mill they are ready for electroplating.

Some people are afraid to run spherical mounts on their street or dual purpose cars, mostly from a lack of knowledge. The important part of any spherical mount is that they are sized appropriately, that they fit the shaft they are attached to properly, and they allow "no bind" articulation at the rear shock mounting point.

There are three ways to make a rear shock mount for a "pin" style upper shock shaft. The OEM style rubber bushing assembly allows the proper articulation of the shock under suspension movement (it pivots at this mount) but has added deformation that you don't see with a spherical. They can also fail spectacularly. Polyurethane shock mounts are too rigid and do not articulate well during suspension movement, causing bind. This bind allows unnecessary flexing of the rear sheet metal where it mounts and makes the car handle poorly.

Vorshlag Spherical shock mounts do a better job than the other two - a metal spherical ball bearing that smoothly articulates with no bind. The tolerances between the shaft and the spherical bearing are very tight - using custom machined bushings we tailor make for each configuration (see above). Spherical shock mounts are all you see on a race car for good reason, but our design is also applicable to street use - for dual-purpose cars that see some autocross or track time.

Vorshlag spherical shock mounts are machined and assembled in-house with the same proven design and years of testing

Vorshlag spherical shock mounts use the largest spherical bearing on the market (19mm ID) - it is massive, which means it is strong. We use a U.S. made, Teflon lined, aircraft quality stainless spherical ball, stronger than the commercial grade import sphericals used in many competitors' shock mount designs. The spherical bearing location itself has been raised above the shock tower, to increase overall bump travel for your rear shocks.

We have tested this design for 4+ years and they are silent, effective, and have no slop or bind in use. If you somehow manage wear out the massive spherical bearings in these shock mounts, we can rebuild them quickly and cost effectively here at Vorshlag.

OPTIONAL INSTALLATION STEP

The upper mounting area for the C5 and C6 rear shock goes into a "blind" pocket between the steel upper shock mounting section of the frame and the flat fiberglass floor. The stock rubber shock mount has two mounting holes and thru-bolts that attach into threaded holes in the chassis. Works fine for stock, non-adjustable dampers... but if you have an adjuster knob on top, how do you get to that?

This optional step allows easy access for dampers with an adjustable knob accessible on the top of the rears, since you might want to turn those knobs you paid for.

We drill these "access holes" with a 2" hole saw into the fiberglass rear floor section of C5 and C6 Corvettes all the time. How do you line them up? First, remove the shock. Then, starting at the bottom, find a really long 1/8" or 1/4" drill bit - something 10" long or more. Now line up the stock upper bushing hole in the steel frame section inline with the shock direction. Then drill a small pilot hole into and through the trunk floor.

Now use a 2" hole saw with the appropriate pilot bit (1/8" or 1/4", whichever you drill from underneath). Match the angle of the shock and drill downward through the fiberglass floor and into the "blind pocket". This should give you ample access to the upper shock knob, without compromising the structural integrity of the floor or touching any part of the frame. The shock knob and upper stem always fit below the level of trunk floor, so if you still have carpet in the car you can cover up the hole. If you are worried about water coming in from underneath (it really can't) you can take a chunk of foam, shape it to fit into this pocket, and shove it in there from above (for when you are not adjusting the knob). All of this makes accessing and tuning your rear shocks possible without removing the shock from the car.

UPPER STEM DIAMETER: These shock mounts are designed to work with virtually any rear shock that is made for the C5/C6 models listed. We use different upper and lower bushings (spool pieces) that we machine to adapt the big 19mm ID of our spherical bearing to the smaller shock shaft diameter of the very top of the rear shock. YOU have to tell us how to build your shock mount assembly by picking the proper upper stem diameter of your rear shocks at the drop down menu below. If in doubt, call us.

Virtually all shocks made for the C5/C6 chassis use a 14mm, 16mm or 22mm diameter main chrome shaft - we don't care about that part. The part we need to know from you is the very top - these can have a 10mm, 12mm or 14mm threaded upper shaft stem. Typically an OEM or non-adjustable shock has a 10mm upper stem but an adjustable aftermarket shock has a 12mm or 14mm upper shaft diameter (MCS with 14mm shown above). The shock mount sits on bushings that fit at step where it goes from the big diameter and necks down to the small upper stem diameter. See these images for a better explanation. If you are unsure about shock shaft upper stem option to choose, please email or call us.

Shipping weight 3.0 pounds. Sold as one pair, for the rear shock location on a C5 or C6 Corvette chassis only.