So, I was reading a thread and someone stated not to use the poly bushings for the suspension. He said everyone hated them. I was wondering why? I was thinking about doing this, but now I may be rethinking it? Are they bad, or is it personal choice?

 

I can only speak for the front end bushings and I have no complaints!!! It's solid, smooth and no squeaks at all!
The only complaint I've heard was the upper control arm bushings working the bolts loose.... I loctite mine without any problems!

 

Cool thanks! I see the prothayne kits are pretty reasonable.

 

My 1978 has poly every where. Running 2 years now. Mainly Track driving, but does get used on the street. They keep my suspension nice and tight. I also marked all the bushing bolts to see if they back out. So far they have not moved. Easier to install but if you like a soft ride and softer steering feel you may not like the poly. For a daily driver / cruse only car the original bushings / rubber would be just fine. You dont feel road vibration as much with rubber. With Poly bushings you will feel more vibration when items are out of balance, eg tire balance / drive shafts / half shafts etc.

 

I actually like that feel and was surprised to find the C3 didn't feel like that. My dad always told me, when I was a kid, that Vettes road like a board. When I bought my first one, 86, id did ride rough, but I liked it. After all, it is a sports car. My Z rode better than the 86, but still very sporty. I was surprised that the 78 feels, soft comparatively. I think I may be purchasing the poly bushings.

 

They're a dumb idea from an engineering point of view and people are now finding that they don't really last any longer than OEM rubber bushings.

 

Despite certain individual opinions that tend to view the poly bushing matter as being rather a black or white one, in reality there are shades of gray area here. At one end of the scale, rubber has long proven to be quite durable and to provide for excellent isolation of road noise and vibrations. However, at the hardcore performance end, eliminating compliance takes priority over either of those characteristics.

So, what about those who aren't necessarily aiming at one end or the other? Poly bushings are rather obviously aimed at the gap left somewhere about the middle, as they do a pretty good job of reducing compliance without completely removing isolation.

That said, they do present some trade-offs. First, and foremost, they require proper initial and routine lubrication to avoid binding stiction (evidenced when they begin to squeak). Also, simple 2D ones aren't suited to linkage points which are geometrically designed to move in 3D's, such as at the rear TA's and camber struts, or on components such as CA shafts when they're not be true. I can see where durability can be an issue in these latter types of locations, and that poly isn't likely to live as long as rubber. But, as for contributing to a harsh ride, one would have to have a fairly soft backside to have an actual complaint about that (sorry, JMHO).

No, poly isn't the unobtainium we might like it to be, but if one is aware of and willing to deal with its shortcomings there are indeed applications (given that it's only used in appropriate locations) when it is definitely worth consideration. Hope that's worth $.02


TSW


edit - FWIW, poly CA bushings are available with serrated inner sleeves, which reduce the likelihood of loosening.

 

I went with poly, but chose the black as it has impregnated black polyurethane with graphite to add a lubrication property to the mix. Keep in mind, both red and black polyurethane components are engineered differently than OEM rubber components. They have been designed to be a free floating and non-binding design, unlike the press in, binding design of the factory rubber bushings. This allows for the additional firmness of the components, which adds to the performance improvement of the vehicle overall in my humble opinion. This said, you'll get opinions on both sides of the isle. I would have went rubber if poly wasn't available in black. I don't think red fits the bill on my Vette. Also, the impregnated graphite is a plus, something that would certainly fit the bill in this application.

 

I almost went with poly when I was rebuilding our goat, but my neighbor talked me out of it with a simple question.
"If the stock rubber bushings from the factory lasted a good 40 years.... how old will you be 40 years from now, and will you care if they`re worn out then?"
This, plus the stiffness of the ride, and the poly was way more expensive than the rubber.
For those reasons, I`m also going with rubber on the Vette.

 

Thhskunkworks and some others have given you some good advice. To me, putting poly bushings on my car had nothing really to do with the poly lasting longer than rubber-they both will last a long time. Having owned my 78 gymkhana equipped car now forr 32 years and having changed/upgraded every suspension part over those years, I realised the C2/C3 suspension is pretty good but the key to improved ride and handling is better tires and the elimination of all unwanted suspension movement-rubber bushings allow the suspension to move when it should not especially in conjunction with a frame that is too flexible. Just about all my suspension points have poly except the noted exception of TA arms and strut rods and the IMPROVEMENT in ride and handlling is amazing. Poly does not make the car ride harsher just firmer with less slop-not my definition of riding harder. It is a relatively easy and cheap upgrade that I highly recommend even if you don't road race-I don't with my C3. Poly makes the C3 more of a Sports car versus blvd cruiser.

 

The press-in binding feature of rubber bushings is very desirable and is in part what makes them superior to a 'free floating' design like poly bushings.

 

Choice of what you use is entirely up to you. For a regular driver Corvette, you do not need poly.

 

I have all poly, rubber tires though.

 

if you are worried about ride quality, your choice of spring and shocks will have a much greater impact on ride quality than poly bushings in my real world experience. Unless you have used both poly and rubber on the same car, most of the opinions are just that opinions.

 

If that is the case Mike, why do race cars run aluminum on Delrin. I'll answer. Because they want no binding, no stiction and no flex because flex at the bushings changes steering geometry. Delrin is many times tougher, harder and stiffer than ploy. Some racers even use steel bushings.

Poly is a good compromise between aluminum/Delrin and rubber for the street and occasional track time. It works well on the street and helps stiffen the cars for track. I have it in both my Vette and my 64 Impala SS. It has been in the 64 SS for 9 years with no issues and shows no sign of where. I drive this car in the summer too. The rough ride is urban legend. The springs, shocks and tires are where the ride comes from.

 

If you want to play boy racer on the street go right ahead. No actually, don't. Put it on the track where it belongs.

Race cars have all sorts of features that are not a good idea, or are a very bad idea for street driven cars.

 

Rubber in mine. I actually removed some poly when I did my suspension over. I still have poly motor mounts and front diff bushing though. those will be put back to rubber soon.

 

All rubber in mine, and the car handles and rides very well.

 

I don't race on the street. I raced professionally for many years and was and still am involved in many other peoples drag racing, road racing and land speed racing at Bonneville, Muroch (pre 911) and El Mirage. I and my customers/partners have a lot of world records and wins. I'm no boy racer. No need to insult me!

I am 60 years old and have been building cars and motorcycles since my early teens, so I have a little insight on this.

The statement about binding as being desirable is BS. Stiction is avoided at all costs in performance suspension.

Poly is not for all out race cars. I just like a tight car and it is a good compromise to solid bushings for street cars used for track days and autocross. I like to autocross my street car now and then. I may do a track day or two also.

If you don't like poly, that's fine, but that doesn't make it stupid and opinion isn't fact!

 

Thank you all for the insight, regardless of what side of the coins you are on. For me, it really isn't about racing, or anything like that. It is about overall handling. I am in the market to change the bushings, because I am noticing the rubber ones are dry rotted and are going to need changing soon anyway. I will probably go with the poly, because as others have stated, I like the firm, tighter ride. My car is an auto so I doubt I will be SCCA racing it anytime, but I may take it to 1/4 track once I can make it get out of its own way. With the other suspension mods I plan on doing, it only makes sense. After all, it is a Vette, and regardless if it is the track, or the street, it should handle above all else.