blue86iroc

iTrader: (2)

I want to put polyurethane bushings on my car, and I was thinking of buying the Spohn Polyurethane Bushing Kit (I believe Prothane is the company that makes the individual parts). For $140, this kit includes every bushing for the entire car, plus a poly tranny mount (it doesn't include a sway bar bushing, though). Does this sound like a good idea? For an IROC, my car handles like crap and I'm hoping that this will help. Spohn products are generally trusted by this board, but I'd like to hear what other people think of his bushing kit. Here's the link (it's the very last item):

http://www.spohn.net/index.cfm?fusea...&categoryid=47

philoldsmobile

I would NEVER recomend poly bushes, I have just fitted a poly trans mount and its coming off, it transmits tons of vibration.

my local parts supplier told me of a local person that totaly poly bushed a 71 RS when it was restored. the car was undriveable due to harshness / vibration.

poly bushes firm up things 500% be carefull where you use them. maybee rollbar only?

blue86iroc

iTrader: (2)

See, I've heard both sides of the story. Some people I talk to say that polyurethane bushings make the car "feel" much better, and they only squeak if they aren't lubricated properly. Others say that they'll give a really bad ride. If I don't go with polyurethane, what else is there? Just the OEM replacements?

philoldsmobile

I personaly would go with this.

poly roll bar bushes

new OEM bushes in EVERYTHING else

good quality uprated springs / dampers

it only takes a tiny bit of wear in each bush to make a car feel soggy. poly bushes in lower wishbones should help stability on the brakes.

try to avoid poly in anything that moves on the virticle, thats where the hard crashy ride comes in.

a very clued up friend of mine said that the reason that my car vibes with a poly trans mount is that with the box heald steady it is exagerating the movement at the engine mounts instead of spreading it evenly.

IROC's were the best handling domestic car when they were new, so a well sorted one should still handle well. GM spent millions getting the best all round compromise, $150 of rock hard plastic is unlikely to dramaticly improve it without compromising comfort severely.

JamesC

iTrader: (5)

I think the decision you need to make is whether you desire a comforable ride or whether you desire a better handling car. By the way, note my sig, my set-up is greaseable and squeak free. Prothane claims their LCA bushings, the ones most folks fuss about, are 'squeak free.' Should you try them, please let us know. I'm very interested. To this point, I've been considering Global West's Del-a-Lums (though pricey, these are greaseable as well). The ride in my car, though certainly firm, is far from bone-jarring harsh.

JamesC

Hulk0202

I have poly front end and have no complaints. No squeaks, and the added stiffness is great for handling. It doesn't ride that stiff, just gives it a good sport car feel. 500% stiffer? If it were that much stiffer you'd be rattled right out of the car.

blue86iroc

iTrader: (2)

I'm not too worried about stiffness, actually... I want my car to handle better even if it does get a little stiffer. I just can't deal with squeaking. Squeaking shouldn't occur if the bushings are greased properly, correct?

BretD 88GTA

Keep them greased and they won't squeak. They also won't make yor car 500% stiffer. That's an overly extreme statement. If you want the car to handle, then poly is the better way to go for a street driven car. You're going to have to give up some comfort to improve performance. That's just the way it works.

I have poly thoughout my car AND I have spherical rod ends on the rear axle. It is a little harsh but it isn't that bad.

Stay away from poly motor mounts though. Those will transfer quite a bit of vibration into the car.

blue86iroc

iTrader: (2)

Then to answer my initial question... would it be a good idea to go with Spohn's polyurethane bushing kit? He doesn't provide a list of exactly what it includes, but his site says that it includes "every bushing to do the entire car" minus the sway bar bushings. That being said, I'm assuming that it comes with polyurethane versions of these:

Polyurethane Transmission Mount - GM $22.50
Polyurethane Torque Arm Bushing $14.50
Polyurethane End Link Set - Front Sway Bar - (82-92) $13.95
Polyurethane Front Control Arm Bushings - (82-92) $29.95
Polyurethane Panhard Bar Bushings $16.95
Polyurethane Rear Lower Control Arm Bushings $49.95
Polyurethane Motor Mounts (82-92) $35.95
Polyurethane Tie Rod Boots $3.95

I won't use the poly motor mounts... is there anything else that isn't recommended in polyurethane?

jRaskell

As a kit, I opted not to buy it for a few reasons.

1. I bought Spohn LCAs and panhard bar, which came with poly bushings.

2. I didn't want transmission and engine mount poly bushings for vibration reasons.

3. I got poly endlinks with the swaybar bushing kits I bought for my car.

So this left me with no reason to buy the kit, since I've got almost everything that is in the kit and most of the rest of the kit I didn't want on my car anyways. Alls I have left now are some tubular lower control arms for the front and tie rod ends.

As for the pro's and cons of poly... My LCAs, panhard bar, and front swaybar all have grease fittings to keep them lubbed. I've got a couple tubes of the synthetic grease from Spohn with a grease gun. As long as they're lubbed, they're quiet. As far as when to lube them. I use the sqeaky wheel gets the kick methodology. Basically, I lube when they squeak.

As for ride harshness, I haven't really noticed the ride get significantly rougher then it was when the suspension was stock. I have noticed it get a LOT firmer, and a LOT more predictable and controllable when the tires start to slide. My rear end in particular is a lot more gradual in it's traction loss. With the stock components, when I lost traction in the rear, it was sudden and serious, and tough to control. Now, drifting is almost second nature.

philoldsmobile

mmmmm, interesting......

I have to admit that the only poly bush i have ever tried on an american car was the trans mount, and that was a total disaster!

I have owned and driven european cars with poly bushes and these varied from stiff to unusable, but looking at it now they were much stiffer suspended to start with.

as for squeeks? no, i've never noticed them. you've got me thinking now, I might try some poly bushes on my front roll bar!

maybee my bad experience of poly bushes was due to the fact that the car i was using them on weighed 2200 lbs and was stiff as hell to start with, exagerating the increase in stiffness! they probably suit heavier cars like camaro's a lot better, they might tighten up my 86 V8 sport coupe nicely