POLYURETHANE MOTOR MOUNTS - look like a better- longer lasting design ?

[craig]

My 2001 (with auto trans) is beginning to indicate it needs new motor mounts. when I got it used, 6 years ago - it had just had new motor mounts - probably cheapest like its replacement vinyl rag top.
I have only put about 10K on the car. I'd like to put in a set of mounts that will last. The miata-speed competition mounts seem like a decent set - BUT THEN - I saw the polyurethane competition set with varying hardness bushings - for ride stiffness. These are a completely different & tougher design with a trough bolt - NO RUBBER TEARING HERE - they have a different 3 bolt mounting base, & even with the softer bushing - will probably outlast me. Since my mechanic gets $200. to change mounts, & since my car seems hard on them - it may be a better investment to go with the tougher new design. Anyone else use these ? How often do the Differential Mounts need replacing - how can you tell ?
Thanks, C.

[iscariot]

Don't go poly unless you're going full racecar. NVH is dramatically increased. And yes, it's 'livable', but not recommended for 'longevity' purposes. OEM mounts already lasted 20 years, they'll last another 20.

[wildfire0310]

The mazdaspeed mounts where a great set and loved them on my old ride.

Full agreement with Iscariot, no reason to go poly unless you are building a track ride but given how your post reads, I would go with OEM again or OEM+ (aka mazdaspeed based parts).

[craig]

Don't go poly unless you're going full racecar. NVH is dramatically increased. And yes, it's 'livable', but not recommended for 'longevity' purposes. OEM mounts already lasted 20 years, they'll last another 20.

THEY DIDN'T LAST apparently - I was told by previous owner - that it went through engine mounts & VIBRATED. It had just got new ones - when I bought it. The vibration is back after 6 years now. I was not babying it - & the PO may have put cheapo aftermarket mounts in.
I asked about the poly mounts because they come in varying degrees of stiffness - that will NEVER TEAR IN HALF - due to different horizontal through bolt design. Was hoping to find someone who Has experienced the softest of the Poly mounts - to access their practicality for me - I know they'd never tear in half. I had Polyurethane engine mounts & suspension replacements - in a 67 box top Bronco - they worked well during the 10 years I owned it. Unless I can learn more about the soft poly mount - I'll probably go with the Mazda Speed original style mounts - but I liked the idea of never needing a RE-DO

How often do Differential mounts go bad ? how can you tell they need replacing ?

[wildfire0310]

THEY DIDN'T LAST apparently - I was told by previous owner - that it went through engine mounts & VIBRATED. It had just got new ones - when I bought it. The vibration is back after 6 years now. I was not babying it - & the PO may have put cheapo aftermarket mounts in.
I asked about the poly mounts because they come in varying degrees of stiffness - that will NEVER TEAR IN HALF - due to different horizontal through bolt design. Was hoping to find someone who Has experienced the softest of the Poly mounts - to access their practicality for me - I know they'd never tear in half. I had Polyurethane engine mounts & suspension replacements - in a 67 box top Bronco - they worked well during the 10 years I owned it. Unless I can learn more about the soft poly mount - I'll probably go with the Mazda Speed original style mounts - but I liked the idea of never needing a RE-DO

How often do Differential mounts go bad ? how can you tell they need replacing ?

So the flaw in your thinking is that engine mounts and such are a wear item, as rubbers and similar products break down. Granted it's normally 10+ years before they start to break down and even then can go longer before breaking apart. Now fluids, such as brake fluid can weaken rubber but seems odd to fail in 6 years.

What I would do in your case is get the car in the air, and look at the mounts while a second person pushes on the motor side to side. If you see tears in the rubber then the mount is failing.



Tears tend to be near the top and bottom. Also, this test will show you if the mounts are just softer than you want if there is a lot of play in the motor.

As for diff, again visual inspections for tears in the rubber and pushing/pull of the diftf. A little harder due to the PPF but basic idea. You can always get photos to post on the forums and someone here can lead an eye too.