|Originally posted by racingfortheson:|
I'm doing a 4.9 swap and plan on using the poly cradle bushings and Moog rubber arm bushings as you wrote in your cave.
V8 should be fine most times if not all the time. Much of this depends on how engine/trans mounts and dog bone planing.
Hard launch for drag racing etc then might distort any soft bushings enough to get some trouble but only at launch time.
And Poly CA bushings will see this too.
Poly cradle is allot harder then rubber but does compress some. Good because could prevent breaking things.
Steel or Al cradle "bushings" can have issues too, Even if aluminum is hard anodize...
Example: Steel shell stuffed w/ aluminum could be problem from road salt etc.
Shell steel is softer then steel for cradle. Soft enough can be pressing in and deform to fit the cradle hole.
Important because Al to Steel "interface" will have voids that water etc will go into and rust from inside. If was me, I would use Super 300 etc to seal up any voids. (I do same thing for axle seals for this reason. In that case, Stopping leaking oil thru any scratches in the trans hole.)
Poly installed dry could have same issue but poly will try fill most voids where it meets the shell. Poly does get some pressure after install w/o load for car. Front Poly is push into the shell then inner sleeve is push into poly. Rear poly has metal part compressing the pieces. Poly will cold flow a bit for this reason and seal most voids. (Pulling Polly front cradle after 10+ years is not easy. I have tried.)