Sphericals or Urethane.... that is the question..

[Steve1968LS2]

Can't seem to decided..

It's between this: (I just need the fronts)
http://www.pfadtracing.com/catalog/p...roducts_id/104

And this:
http://www.pfadtracing.com/catalog/p...products_id/43


Price isn't the issue.. I worry about going too "race car" but in the effort to squeeze out the most performance it's so tempting to go that extra step.

I know the spericals are technically better and offer zero deflection, but I worry about how much harshness and noise they will add. The urathane are pretty good as well and since they offer alum sleeves they don't have the same "issues" as regular urathane units. And they offer less harshness and noise.

According to Pfadt they remove 90% of the deflection.. So, the big question what is that extra 10% worth?

The big benefit of the spericals is that I can run less neg camber..

Thoughts?

Oh, here's an interesting video showing stock bushing deflection:
http://www.youtube.com/watch?v=nkrH4...e=channel_page

[Steve1968LS2]

I will also be running these:

http://www.pfadtracing.com/catalog/p...roducts_id/123

And these:
http://www.pfadtracing.com/catalog/p...roducts_id/129


Just seem like good mates to the new billet uprights...

[CarlC]

.....must use spellcheck for thread title.....

Sphericals.

[MuscleRodz]

How much do you actually drive Penny on the street? You are taking the rest of the car the last 10%, why stop here?

[JDP Jordan]

I forgot to mention this earlier, I was just excited talking cars with you!

Here are the biggest differences:

The spherical bearings offer zero deflection and they also allow the suspension to articulate better. For example, before we installed them in our C5 you could stand on the splitter and it wouldn't move with the poly. We installed the spherical bearings without changing spring (650 lbs) and the front end moved up and down freely. It does however increase NHV, nothing crazy as some people can handle it and some can't.


For Sale 888.972.2464

The poly produces more friction then the bearings, however it is much better than bonded rubber.
The polyurethane is a huge improvement over the rubber however. The rubber bushings are bonded into the control arm causing an elastic effect, not to mention major deflection which will effect your camber under load. The poly removes most of this deflection but it doesn't increase the NHV nearly as much.

Both products will allow you to run less negative camber as you won't have as much deflection, in your case it is a toss up! If it were me I'd probably go with the spherical bearings, they are a great product. Talk to you soon!

Jordan
Pfadt Race Engineering

[zbugger]

You've run the Delrin stuff before, right? It should be too much different from that. At least not much more harsh. Could very well be smoother as well. Now, I'm not trying to talk you into the sphericals, although I'm not trying NOT to either. But if you really want the car to go all out, I say do it. But you also should see what Dave and Mary say. I think they'd say to do it the spherical way.

[JDP Jordan]

How much do you actually drive Penny on the street? You are taking the rest of the car the last 10%, why stop here?

[Steve1968LS2]

.....must use spellcheck for thread title.....

Sphericals.

Be my copy editor???

[Steve1968LS2]

How much do you actually drive Penny on the street? You are taking the rest of the car the last 10%, why stop here?

Well.. I've driven 3,000 miles on the street and maybe a 70 miles of that was on some sort of track. :shrug:

I just don't want to get so carried away with performance that I kill what the car was always meant to be.. a streetcar that can go to the track..

Thanks for the input.. either will be a vast improvement..

[Damn True]

For Sale 888.972.2464



Jordan
Pfadt Race Engineering

Is that the car you guys had at the 25hrs of Thunderhill?

Great looking machine. A shame it just wouldn't hold together. What kept breaking?

[MuscleRodz]

Well then start with the urethane, and if they don't do the trick, then go full monte on it. That way you dont have to wonder if the urethane would have benn "good enough"

[silver69camaro]

I agree, urethane first. You have to burn out the old bushings for either one, so I'd start small. I'd approach this like choosing a camshaft, start on the small side first.

Remember, if you go to far into "race car" territory, the car is no longer fun to drive on the street...which is apparently where you drive 97.7% of your miles.

[JDP Jordan]

Is that the car you guys had at the 25hrs of Thunderhill?

Great looking machine. A shame it just wouldn't hold together. What kept breaking?

Thanks! It is pretty crazy!

The issues were small but big enough to hold us back. We ran the 3rd fast time overall behind to DP cars. We had a contaminate in the fuel system and once we got it completely flushed the clutch started slipping. Nothing major and it was a learning experience. The car is crazy fast!

This car also won the NASA ST1 National Championship, that was an exciting race!

[JDP Jordan]

I agree, urethane first. You have to burn out the old bushings for either one, so I'd start small. I'd approach this like choosing a camshaft, start on the small side first.

Remember, if you go to far into "race car" territory, the car is no longer fun to drive on the street...which is apparently where you drive 97.7% of your miles.

The bushings actually press out of the C5 control arms. It's much cleaner and easier! I hated burning bushings out. I think this is a good suggestion though.

[Norm Peterson]

The urathane are pretty good as well and since they offer alum sleeves they don't have the same "issues" as regular urathane units. And they offer less harshness and noise.

According to Pfadt they remove 90% of the deflection.. So, the big question what is that extra 10% worth?

The big benefit of the spericals is that I can run less neg camber..

Thoughts?

Take the "90%" at face value and put a few more numbers on it. I think I saw "over 0.25°" mentioned in one of those links, so let's estimate 0.5°. Cutting that down by 90% would leave 0.05° as the remaining compliance camber effect. Downstream compliance effects on toe should be similarly less as well. Your call as to eliminating the last 10%.

Polyurethane's "stiction" effects can be mitigated, but I doubt that the sleeves being aluminum has much to do with that unless they were chosen considering long-term use and the possible development of corrosion on the outer surfaces of the sleeves.


Norm

[Steve1968LS2]

Take the "90%" at face value and putting a few more numbers on it. I think I saw "over 0.25°" mentioned in one of those links, so let's estimate 0.5°. Cutting that down by 90% would leave 0.05° as the remaining compliance camber effect. Downstream compliance effects on toe should be similarly less as well. Your call.

Polyurethane's "stiction" effects can be mitigated, but I doubt that the sleeves being aluminum has much to do with that unless they were chosen considering long-term use and the possible development of corrosion on the outer surfaces of the sleeves.


Norm

You're always like talking to my doctor.. lol. It takes a couple of tries before I figure out what exactly you're really saying.

[CarlC]

Be my copy editor???

I do that for customer technical reports for five guys at work. What's one more?

I get to be gutterball here.

You still missed the spellcheck button. Urethane. Plus, I meant sphericals as the choice. I'm not at all sorry for going that way on the leaf springs.

I have a $1 on what David says.....

[Steve1968LS2]

I do that for customer technical reports for five guys at work. What's one more?

I get to be gutterball here.

You still missed the spellcheck button. Urethane. Plus, I meant sphericals as the choice. I'm not at all sorry for going that way on the leaf springs.

I have a $1 on what David says.....

For some reason spell check has never worked here for me. Actually it does if I use Firefox instead of IE.

Man, you guys are expensive to get advice from.. lol

[jaybee]

"The poly produces more friction then the bearings, however it is much better than bonded rubber." Interesting statement and one that I've wondered about for some time. Many on this board prefer DelAlum and I presume this is because of their devotion to wringing the last ounce of potential out of their car in track day and autocross. That's certainly admirable but sometimes the goal of a car that's significantly better than stock crashes headlong into budgetary reality.

[David Pozzi]

I think it's a toss up too! The Herb Adams Camaro I drove back in 1984 had spherical bearings in the lower A arms and was just fine to drive. We switched it to poly bushings to make it legal for the SCCA national autocross event, and I couldn't tell the difference driving it on the street. Not really any difference on the autocross course either, but in theory the poly will always add some extra friction. We ran stock spring rates, so maybe the extra friction didn't hurt anyway.

I like the spherical bearings, (but I'm not writing the checks) you can always pull them out and sell them if you don't like them. They will feel slightly more harsh on a sharp bump, like when you hit tar strips on the freeway. The Poly is a very close second choice in my book, and a good compromise between race and street. We have Delrin on Mary's 73 Camaro and they are a great way to go. If the choice were between spherical bearings, poly bushings, and Del-A-Lum/Delrin, I"d pick Delrin.
David