To meet USA laws, the Scorpion suspension was set about one inch higher than that of the Montecarlo. This was acomplished with longer springs (with different load rates), but otherwise the setup is very similar to the series 1 Montecarlo.
Rebuilding Scorpion Struts
The majority of Scorpions will have had or will require work on the suspension struts. Sadly these original pieces are not available new. Short of re-engineering the whole suspension or purchasing a complete kit from the Monte Hospital; one option is to try and rebuild the struts themselves with new seals.
Bernie Benz is quite an expert on struts and has made many modifications to the Lancias and Audis he owns. He wrote this following piece for Lanciana.
One can very successfully rebuild either the original equipment Beta struts (those with removable heads, late units have a rolled-in-place head closure which I have not attempted to disassemble) or the Koni after-market, full strut replacements, for minimal cost and with both life and performance better than new!
In background, lets review basic shock strut principals, design, and failure modes. Apart from being a major component of the suspension geometry, the primary function of the strut is to absorb and dissipate unwanted energy. Bump energy is stored in the spring as it is compressed and this energy is then dissipated in the strut in a controlled rebound release to eliminate wheel oscillation. Thus, the strut applies the damping necessary to control the resonant oscillations of the spring and mass of the suspension; a highly tuned dynamic mechanical mechanism.
Valving: First, the foot valve system, a bi-directional valving system located in the closed bottom of the cylinder, allowing fluid to freely enter the lower cylinder volume from the concentric outer reservoir as the piston moves up (wheel moving down in a "rebound") and prevents reverse flow (below a preset relief pressure) returning from the cylinder to the reservoir upon piston down stroke (wheel moving up in "bounce"). Second, piston internal valving is also a bi-directional valving system, each controlling the differential pressure required for fluid flow from the high to the low pressure side of the moving piston; one valve system for each direction.
That's all there is to valving, but in addition to these pressure operated valving systems which control fluid flow, there are wear-related leakage paths that short circuit the valving systems and degrade damping performance. In MacPherson struts both the piston and the rod bushing, are subject to considerable wear-causing lateral forces, i.e. the reaction forces of acceleration, breaking and cornering. Thus, these are the primary internal wear related failure areas, and are further described as follows:
Rebuilding: First, before disassembling the strut, inspect the piston rod. If the rod has been running dry long enough to have worn through the chrome plated finish, replace, don't attempt to rebuild.
Next disassemble the strut, dump the fluid, and clean the parts in solvent. Do not disassemble the foot or piston valving, as these components are not subject to degrading wear.
For rebuilding the Beta struts Lancia has top end rebuild kits available which contain the complete head assembly (head with bushing and drain tube, seal housing with rod seal and scraper, o-ring and nut) for about $30 each. I have rather elected to replace individual worn components to incorporate design improvements for less than $10 each. By rebuilding at the component level one can increase the bushing length by 1/8" or 1/4" (Beta struts), thus increasing bearing area comparable to Koni, maybe doubling wear and leakage life. The bushings are of the Teflon/powdered bronze lined, split steel shell type in both struts, Garlock DU being the American made brand. Although I have identified a replacement seal for the Beta struts, I have not found it necessary to replace the later, spring loaded lip type. Early Beta seals were not spring loaded, and thus should be replaced. Koni uses a special combination seal/scraper for which I have no replacement but then. Garter spring loaded seals normally do not need replacing unless they have been running dry for a long time. As the new bushings and adequate drainage minimize the seal pressure.
Nylon piston ring wear is corrected by placing a paper shim behind the old nylon wear ring in the bottom of the piston ring groove. A.0025 to .005 thick, as required, bond paper ring reduces the piston clearance in the cylinder to a light push fit. I have replaced the Scorpion steel piston ring with a tight sealing Quad ring (a quad section O-ring that is not subject to spiral failure) which improves performance under short stroke conditions by eliminating leakage at low piston velocities.
As for replacement fluid, automatic transmission fluid (Dextron ATF) has ideal characteristics for this high shear rate application, and it has a viscosity (180 ssu @ 100F)just slightly higher than the stock fluids.
Filling: With fluid in the reservoir submerge the foot valve end of the assembled insert and prime the cylinder by stroking the rod, When the cylinder is completely full ( fluid weeping through the bushing clearance) and with the piston at the bottom of the cylinder, lower the insert to the bottom of the reservoir. In this assembled position the reservoir fluid level should be about an inch below the head; i.e. minimum air space in reservoir of about one inch.
Last, button up the head using a new O-ring static seal. With this rebuild and improvements, the strut will be better than new. Piston ring and rod bushing wear being the likely cause for the next rebuild in about 30 to 50 thousand miles.
Last updated: 2002-09-01