Geoff Coenen
Well-known member
More BS from a few “respected” Corvette part suppliers.
I noticed over seven years ago that the 2 round Cushions that mount on the small rods protruding at the bottom of a 1961-1972 Aluminum Radiator were being also marketed as PS Cylinder rod round Grommets. Although they have a superficial resemblance – they are vastly different in function, durometer and even size.
I’m not sure these suppliers are either ignorant or simply greedy. Years ago, I made a video that showed the 1961-1972 Aluminum Radiator Cushion GM # 3786786 side by side with the 1963-1982 PS Cylinder Grommet GM # 3709452.
PS Grommets v. Radiator Cushions
The rubber in the Radiator Cushions is soft in comparison to the rubber in the PS Grommet. The rubber in the latter is as hard as a hockey puck for good reason. It must absorb the power of the hydraulic ram as it pushes against the static PS bracket on the driver’s side frame rail as the ram pushes the relay rod to move left and right for turning,
There is little discernable movement in the radiator cushion, as it merely sits in pocket on the radiator support. It is much soft rubber and truly acts as cushion as do all the various 1953-1982 radiator mount rubber cushions.
Recently on the ncrs char room a fellow took his TWO PS Grommets off the ram and thinks they are different sizes. Unsure is they are original GM, he also noted one surface has concentric ridges and the other surface appears stepped. The stepped side has been deformed as it faces frame bracket and has been squeezed against it; The concentric ridges mimic the special steel retainers that look like way bar link retainer but are also vastly different as they have concentric ridges that add to their strength. When GM sold those steel PS grommet retainer’s they were expensive over $10 list each. They also had to be strong and tough to take the power delivered by the hydraulic PS ram.
Hopefully someone will educate these “misguided” vendors - unless their goal is merely enhancement of their pocketbook.
PS In all honesty – I had both these rubber parts extruded by a major US manufacturer. They were also different in price due to their differing composition. Radiator Cushion less expensive; PS Grommet more expensive – 9 times more expensive – run by the same exact rubber extruder.
I noticed over seven years ago that the 2 round Cushions that mount on the small rods protruding at the bottom of a 1961-1972 Aluminum Radiator were being also marketed as PS Cylinder rod round Grommets. Although they have a superficial resemblance – they are vastly different in function, durometer and even size.
I’m not sure these suppliers are either ignorant or simply greedy. Years ago, I made a video that showed the 1961-1972 Aluminum Radiator Cushion GM # 3786786 side by side with the 1963-1982 PS Cylinder Grommet GM # 3709452.
PS Grommets v. Radiator Cushions
The rubber in the Radiator Cushions is soft in comparison to the rubber in the PS Grommet. The rubber in the latter is as hard as a hockey puck for good reason. It must absorb the power of the hydraulic ram as it pushes against the static PS bracket on the driver’s side frame rail as the ram pushes the relay rod to move left and right for turning,
There is little discernable movement in the radiator cushion, as it merely sits in pocket on the radiator support. It is much soft rubber and truly acts as cushion as do all the various 1953-1982 radiator mount rubber cushions.
Recently on the ncrs char room a fellow took his TWO PS Grommets off the ram and thinks they are different sizes. Unsure is they are original GM, he also noted one surface has concentric ridges and the other surface appears stepped. The stepped side has been deformed as it faces frame bracket and has been squeezed against it; The concentric ridges mimic the special steel retainers that look like way bar link retainer but are also vastly different as they have concentric ridges that add to their strength. When GM sold those steel PS grommet retainer’s they were expensive over $10 list each. They also had to be strong and tough to take the power delivered by the hydraulic PS ram.
Hopefully someone will educate these “misguided” vendors - unless their goal is merely enhancement of their pocketbook.
PS In all honesty – I had both these rubber parts extruded by a major US manufacturer. They were also different in price due to their differing composition. Radiator Cushion less expensive; PS Grommet more expensive – 9 times more expensive – run by the same exact rubber extruder.
