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It's a mine field on this call. Not sure there's a clear answer.
I've had too many problems with polyurethane bushings and other parts just disintegrating, some never loaded or used. Quality is all over the map on pu. (I've also worked with pu in industry and it's fine if molded correctly, but a lot of parts are pour molded, and the results can be most anything.) On the other hand I've seen some limited reports of the same thing happening to the Danchuk rubber mounts.
I'd go with the rubber mounts myself, thinking the chances are better.
I went with poly mounts on my Nomad. I have no experience with them but I know rubber ones will flatten over time. I think that's less of a problem with poly, but I'm not sure.
56 Nomad, Ramjet 502, Viper 6-speed T56, C4 Corvette front and rear suspension
Other vehicles:
56 Chevy 2-door BelAir sedan
56 Chevy 210 4-door sedan
57 Chevy 210 4-door sedan
1962 327/340HP Corvette
1961 Willys CJ3B Jeep
2001 Porsche Boxster S
2003 Chevy Silverado 2500 HD Duramax
2019 GMC Sierra Denali Duramax
It's a mine field on this call. Not sure there's a clear answer.
I've had too many problems with polyurethane bushings and other parts just disintegrating, some never loaded or used. Quality is all over the map on pu. (I've also worked with pu in industry and it's fine if molded correctly, but a lot of parts are pour molded, and the results can be most anything.) On the other hand I've seen some limited reports of the same thing happening to the Danchuk rubber mounts.
I'd go with the rubber mounts myself, thinking the chances are better.
Recently, I have found that the major players/suppliers have change formulation on PU parts. I'm not saying they're better than the old stuff but some seems to be softer or something compared to old parts.
That's one of the problems with the pu, the consistency over time of new parts. The suppliers of pour mold polyurethane often don't maintain control over their product. It puts the people that actually make parts at their mercy. We fought this over and over in the industrial stuff I worked with. On the other hand, injection molded pu is very consistent in its properties and processing. But I'm thinking body mounts aren't injection molded. For one thing the tooling costs a lot more, and this is a big deal for small quantity manufacturing. Injection molded polyurethane also requires proper drying, it is more sensitive to moisture than most plastics that are molded.
My friends 55 chevy has rubber mounts and I have poly. His mounts are only two years old and are falling apart.
I can with out doubt say the ride is stiffer in my car using poly, but I like that. I'm sure poly will last much longer then the rubber junk made today.
My friends 55 chevy has rubber mounts and I have poly. His mounts are only two years old and are falling apart.
I can with out doubt say the ride is stiffer in my car using poly, but I like that. I'm sure poly will last much longer then the rubber junk made today.
I know this about some rubber replacement parts, like the PU, the quality is either perfect or rotten - no in-between.
That's why I said it was a mine field in my initial post.
I had the link bushings for a sway bar fail while just sitting there, installed but never used. I've had a Stanley dead blow hammer just disintegrate. I've had shoe soles disintegrate. All PU.
But rubber can be just as troublesome. Had a deal where we were trying to mold rubber parts at my work. Inconsistency kept us from releasing a product for a couple of years. Not for a lack of trying or getting assistance from suppliers. We finally spent a bunch of money to be able to do more of the process in house.
Trouble with either is that the guy that molds the parts is often not in 100% control of the situation, at the mercy of material suppliers.
Never had a problem with poly-urethane personally. Matter of preference. Used them in a hot 66 Nova and a 65 Corvette. Used reputable suppliers and was happy.
I might eventually go to poly mounts, but in the stage of my build I wanted rubber that's a little more compliant, so I can squish it up or down as needed. I plan to stiffen up the body shell a bunch in the future, but still isolated from the chassis.
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