[bhill86]

Gotta change mine soon and wanted opinions on solid vs rubber replacements. Pure street driven car. Solid seems to be the popular choice but I’ve also read it reduces the ride quality noticeably. Seems like rubber was just fine originally so I’m leaning that way. Thoughts?

[JLMounce]

I have the ridetech solid bushings. They are made from Delrin to help with NVH.

As far as NVH transfer, it really kind of depends.

If you have a stiff suspension with new, good quality rubber bushings and you change to solids, you’ll probably notice some NVH increase.

If you have a soft suspension with new rubber bushings and you go to solids, you may not notice any additional NVH.

If you have old, worn out rubber bushings and you change to solids, you might feel a decrease in NVH.

If you have old, worn out rubber bushings and replace with new rubber bushings, you might notice a good bit of NVH reduction.

The point I’m trying to make is that it depends a lot on what you’re used to with the car and what you are prone to personally. If you’re building a near stock car that is a cruiser with only mild performance upgrades, solids don’t make a lot of sense.

If on the other hand you’ve put an extra 150hp/tq between the frame rails, having solids (and subframe connectors) becomes almost necessary to keep the body from trying to rip itself off the frame.

I have solid body and suspension bushings in my first gen. It’s not a Cadillac, but the ride also isn’t bad. There’s no weird vibrations, buzzez etc. if you hit a big pothole you do feel it a bit more though. If you’ve got missing hardware in the body or loose fasteners, it may exacerbate the NVH that causes.

[bhill86]

Thanks for your explanation. My car currently has new suspension bushings on an otherwise stock setup with KYB gas-a-just shocks. Motor has mild upgrades but I’d be surprised if it was at or much more than 150 HP or TQ over stock. I think my concern is going with solids and hating the harshness. I’m not particularly disappointed with the current performance of the car though i think the bushings are in need of replacement so i tend to think I’d be happy with rubber replacements and that they will still be an improvement over the current ones.

[78w72]

I run poly body bushings in all 3 of my 2nd gen birds.... from what Ive read over the years as well as my experience with them, poly bushings dont make the ride stiffer or harsher especially at the body mounts, nothing is really moving there like suspension bushings & even then many say poly control arm bushings dont ride any harsher than rubber, large majority of the ride is from the shocks & springs & tires... low profile rubber band tires will have a much harsher ride than ones with some sidewall to absorb vibrations.

Poly body bushings are considered more of a solid bushing as they dont really flex, I run them with welded PTFB frame connectors in my 72 firebird with a 500+ hp stroker that does low 11's, bushings look like new after about 10 years and I dont notice any added harshness, using PTFB upper A-arms & their stiffer lowered springs. These cars rode harsh when new, at least when hitting potholes or big cracks in the road, normal smooth dips are fine, but feels like its on rails when hitting a big pothole, where my 4th gen 4runner just glides over big potholes & other bad roads which we have a ton of here in Iowa. So its the design of the car/suspension that older cars cant compare to newer ones.

Energy suspension has a nice poly bushing kit that includes new hardware if the original bolts/washers are rusted. many times they are cheaper than correct rubber kits.

[HWYSTR455]

If you use front structure braces, the ones that go from the cowl/firewall to the A-arm mount on frame, then you have to use solid bushings. If you don't you will crack windshields.

Ask me how I know.

Sub frame connectors can do the same thing, but usually you would have to run weld in type for that to happen. Some actually attach to points on the floor boards.

As for transfer of vibration(s) and/or noise/harshness, it's nominal, almost unmeasurable, with poly bushings. And it's really only slightly more with the solids.

This of course is assuming you also have the suspension optimized for free-articulation and you've used proper springs & shocks.

Most people are 'sensitive' about the vibration(s) because it's been drilled into their' heads for so long. You try extra hard to observe the change and may notice what you didn't before. (And it could have been there with the rubber bushings too).

Most new rear wheel drive cars don't have bushings at all. Think about it. Many front wheel drive cars have mounts for the engine cradle, but that's a different story. Main reason there is for ease of assembly on the production line.


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[JLMounce]

Originally Posted by HWYSTR455

If you use front structure braces, the ones that go from the cowl/firewall to the A-arm mount on frame, then you have to use solid bushings. If you don't you will crack windshields.

Ask me how I know.

Sub frame connectors can do the same thing, but usually you would have to run weld in type for that to happen. Some actually attach to points on the floor boards.

As for transfer of vibration(s) and/or noise/harshness, it's nominal, almost unmeasurable, with poly bushings. And it's really only slightly more with the solids.

This of course is assuming you also have the suspension optimized for free-articulation and you've used proper springs & shocks.

Most people are 'sensitive' about the vibration(s) because it's been drilled into their' heads for so long. You try extra hard to observe the change and may notice what you didn't before. (And it could have been there with the rubber bushings too).

Most new rear wheel drive cars don't have bushings at all. Think about it. Many front wheel drive cars have mounts for the engine cradle, but that's a different story. Main reason there is for ease of assembly on the production line.


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Also good to point out that almost all high end performance builds on classic F-bodies will run a subframe (or full frame) that is welded to the body directly.

[bhill86]

All good points. Any recommendations on where to get a set poly bushings?

[78w72]

Energy suspension... shop around but summit will usually have the best prices & free shipping over $100.

[bhill86]

Thanks! Found a set on Amazon with a good price and free shipping.

[HWYSTR455]

Yes, Energy are the best poly ones, across the board.



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[bhill86]

Good to know. Thank you for all of the replies. May try this next weekend

[Skip Fix]

Thought I posted earlier but not here. I have run Herb Adams, Gulstrand 1/2" drop, and now Global West interlocking and none have ever been harsh. But I don't think my solid A arm bushings feel stiff either!

I have a set of Energy poly for an 81 if you need some.

[bhill86]

I would’ve taken you up on that but I have a set on the way currently. Thanks though

[HWYSTR455]

I swapped out the Herb Adams drop bushings for the interlocking GW ones too. My comment regarding the structural supports are based in using the VSE braces, which mandates the solid bushings.

I took it a step further and added a strap across the top of the cowl. I noticed distortion along the top of cowl from 'heavy' driving.

If the suspension articulates properly, and you dial the springs & shocks to your' own type of driving, there is no 'harshness'.

If you still feel you have excessive 'harshness', you can change to a taller profile tire and adjust tire psi.


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[78w72]

Originally Posted by bhill86

Thanks! Found a set on Amazon with a good price and free shipping.

Did you get the kit with hardware & bolts or just the bushings? The new bolts/washers are nice but you can re-use originals if they are in good shape, Ive pulled original bolts that were almost half way rusted through even on southern cars, water/debris must collect in that area.

If youre not doing the body bushings all at once with the frame off, its best to do 1 at a time, that way the frame doesnt move.

[bhill86]

It’s a kit with all of the hardware. Due to the space restraints in my garage I planned on doing one side, one at a time essentially.

[bhill86]

Now that I have these, I’ve not yet installed them but it’s been brought to my attention the poly body bushings may be noisy with squeaks? Can anyone confirm or deny?

[JLMounce]

Poly can squeak. That doesn't mean they will, but there's a possibility of that. That's actually why you saw the polygraphite stuff in the late 90's. The graphite impregnation added some slippery to the bushing, reducing the occurrence of squeaking. The downside (unknown at that time) was that the graphite also ate at the material and decreased its longevity.

Squeaking from poly is more of a suspension issue because you have parts articulating in and around it. I personally will never recommend a poly bushing in the suspension. The material is used to create bouncy balls, you don't really want that in your suspension arms, plus they don't necessarily last longer that good rubber and have a propensity to squeak. So rubber or solid in suspension pieces only.

I still believe personally, that the body bushings should be thought of in the same way. You either run solid for the performance and structural benefits, or you run good quality rubber for the comfort benefits. Running poly stuff is a compromise in my eyes that doesn't provide much on the benefit scale. This isn't a knock at any one company or manufacturer, but there's a reason so many people push poly this and that. It's because at scale the stuff is nearly free, you're being marketing hyped by these companies so they can sell a product with a massive profit margin. OEM's don't ever use any poly material in cars. If it needs to squish and move, it gets rubber. If it needs to squish and absorb, it gets micro-cellulose foam.

If you've got the poly mounts in hand, I'd install them. Chances are you're not going to have a bunch of squeaking. What you can do to try and help that is make sure the through bolts and washers are greased liberally with white lithium grease. That will cut down on anything metal moving directly against the polyethene,

[bhill86]

Would wheel bearing grease also work? That seems like it might last longer.

[JLMounce]

Petroleum based grease should not create an issue that degrades the product in any way. It may not be the best grease to use since it's not necessarily designed to stick to metal. The silicone and lithium stuff is very tacky and sticks well to both the poly and the metal it will be sitting against.

Energy Suspension recommends their Formula 5 grease which is designed around their product. Or they recommend a high quality Marine grease, which will typically be lithium.