Spherical "Bushings"

[Tristan Smith]

Don't bother there, DD. He had 12 pages of presentation of that position. It's a lot easier to just believe, rather than think critically about something (see also, US Foreign Policy, Culture Wars, and Tooth Fairy, et al.)

K
[/b]

Bite me, Knestis. Or we could sit around and and debate rules that have already been clarified by national...........endlessly. It is not a case of just believeing. It is a case that has already been discussed and clarified. I know you guys love to discuss philosphically the nature of the rules, but some time it feels like "navel contemplation"................endlessly. Granted, I don't have to read it.

Also, the meaning of life is open to interpertation. Like some of our rules.

The sky is blue, because someone protested it, and SCCA National upheld the ruling that indeed it was!

Any other questions. I have answers for them all, and it won't take 12 pages.

[ddewhurst]

***The limited section falls on stock parts with bushing replacement and baby a bearing is a bushing and all of the pissing around here won't chnge that fact.***

Joe, all my 1st gen stuff is on sale. Does that present a clue to you. <_< I moved to the dark side.

[turboICE]

No worries though. The issue was discussed on our con-call...

AB
[/b]

After I left reason and rationality at the door with the instructor commentary, I am going to wait to see what comes out of this discussion. Hopefully a resolution either way - I doubt that the discord among many reasonable people provides support that a conclusion either way is so entirely clear.

[Bill Miller]

Bite me, Knestis. Or we could sit around and and debate rules that have already been clarified by national...........endlessly. It is not a case of just believeing. It is a case that has already been discussed and clarified. I know you guys love to discuss philosphically the nature of the rules, but some time it feels like "navel contemplation"................endlessly. Granted, I don&#39;t have to read it.

Also, the meaning of life is open to interpertation. Like some of our rules.

The sky is blue, because someone protested it, and SCCA National upheld the ruling that indeed it was!

Any other questions. I have answers for them all, and it won&#39;t take 12 pages.
[/b]

Well smart guy, how about you provide us w/ the National &#39;clarification&#39; that states them as legal?

[lateapex911]

Hopefully a resolution either way - [/b]

A resoulution you shall receive.

While the discussion here is based on presumptions and suppositions of the original "intent", the resolution will reflect the actual intent and desires of the rulesmakers.

[Knestis]

Bite me, Knestis. ...[/b]

Munch. :P

Sorry I was a bit abrupt there, Tristan but the reality is that we could each get a letter or email from someone in Topeka, and they would collectively hold absolutely NO water in the actual process. You believe what you believe, just like I believed that there was NO question that we cold all run .40-over pistons. Having looked critically at the wording of that rule, I now understand that it isn&#39;t very clear at all - based on the actual rule, rather than on what I want it to say, think it says, or have been told it says.

There&#39;s been pages of good presentation here, both pro and con the literalist interpretation, and your position seemed to be that there is some "real" documentation of an "official" interpretation that SBs are AOK. There isn&#39;t because there can&#39;t be, under the current system.

K

[erlrich]

A resoulution you shall receive.

While the discussion here is based on presumptions and suppositions of the original "intent", the resolution will reflect the actual intent and desires of the rulesmakers.
[/b]

Jake - care to give us a hint? Should I hold off on ordering those new bushings?

[bldn10]

"This whole debate is moot. Spherical Bearings are legal. They have been for years. They have been questioned by folks to SCCA National, and they were deemed legal."

Tristan, nothing is conclusively legal or illegal until a COA says it is. To my knowledge no COA has published a ruling on the SB issue. Has someone gotten a 13.9? All I know is that it is the opinion of Jeremy Thoennes that they are legal because "a spherical bearing is a bushing" - that&#39;s what he told me. I don&#39;t know Jeremy so I don&#39;t know if he is any more qualified at interpreting rules than I am; he just happens to be in a position (purely advisory) in Topeka so his interpretation carries weight. But I think he is wrong and, unless someone corrects me, and in the words of another poster, it is just "one person&#39;s opinion" - it is not the official position of the SCCA.

"The rules say any bushing material may be used. That means metal that swivels."

Where on earth do you get that? That absolutely does not logically follow. That&#39;s like saying that if a rule said that shock material was free then you could use a shock w/ material that was triple adjustable. Here we go again, another interpretation/conclusion that ignores the fundamental requirement that suspension bushings first and foremost be sleeves or tubular inserts. Nothing about a sleeve or tubular insert w/ a swivel device inside.

I suspect that many if not most cars in classified in IT have at least one component that holds them back and that could be alleviated if it were not illegal to do so. That&#39;s just the way it is. Which is not to say that a rule exception should not be made to allow some cars to be at least competitive. Don&#39;t the rules allow some extra rear suspension mods on 1st Gen. RX-7&#39;s? As far as I am concerned a rule exception could be made for the 240SX if all it will do is allow them to be competitive w/o giving them an unfair advantage against cars that don&#39;t absolutely need SBs to make them driveable. I&#39;m not concerned about having to run against 240s w/ SBs, I just don&#39;t want to have to go out and spend hundreds of dollars for SBs because all the other RX-7s have them. [Does the 2nd Gen. RX-7 need them or even benefit from them?]

[Tristan Smith]

K, no problem.

When I built the 240sx years ago, there was some debate about SB&#39;s, and one of the other 240sx guys asked and got confirmation from national. I don&#39;t have that paperwork. And quite frankly, I don&#39;t who remember who was asking. But I do know that it was asked. I wouldn&#39;t have built the car that way if there was any doubt. The 240sx has to have the "spherical bushings" to not bind. If the "spherical bushings" were taken away from us, we would HAVE to go back to a soft stock rubber bushing. If that were to be the case I would lobby hard that ALL competitors go back to stock bushings. For our cars, the "spherical Bushings" (my new term for them) allow the suspention to function properly, without the slop. It&#39;s the same thing that delrin, or urethane does for everyone else. If we are to penalized in this way, it should be across the board. IMHO.

[Greg Amy]

You&#39;ve inspired me: because of my suspension geometry limitations, I cannot lower my car more than about 1" from stock, a good 3 or more inches above the IT minimum limit; that&#39;s obviously a competitive disadvantage for me. To resolve this inequity, I&#39;m going to lobby the CRB to make all cars raise up to within 1" of stock.

It&#39;s the only fair thing to do, right? - GA

[turboICE]

Ack Greg don&#39;t go there! I have a significant eompetitive disadvantage in my car resulting in an inequity to my car that I wouldn&#39;t want the CRB to resolve - the driver!

Tristan, I had not completely disimilar views not far above. It was communicated in response that the ability to lower the car legally is not part of the consideration for classing potential - invalidating both of our points.

Whether or not something is legal is a question that has nothing to due with whether or not someone benefits or not.

Greg, so as to further my knowledge or satisfy my curiousity (depending on ones view) what causes your suspension geometry to get so scary when lowered below 1" from OEM? I assume it isn&#39;t joint angles, is it linkage lengths, inability to recover alignment?

[theenico]

Does the 2nd Gen. RX-7 need them or even benefit from them?[/b]

In the front suspension they are definitely not needed. The rear suspension, however, benefits greatly by installing one in each trailing arm where the trailing arm mates to the subframe (IIRC, this is the spot with the slotted hole and eccentric bolt where the toe gets adjusted).

On a side note, the little dogbone links are equipped, from the factory, with spherical bushings.

P.S. The proper size spherical bushing for the trailing arm is a 5/8 Aurora part # PNB-10T and the holder for it is available through Charlie or UB Machine.

[Greg Amy]

...what causes your suspension geometry to get so scary when lowered below 1" from OEM?[/b]

At stock ride on a McPherson strut car the roll center of the geometry (the theoretical point about which the car rolls; there&#39;s one in the front and one in the rear) is at a reasonable distance from the center of gravity (and that distance is the "lever arm" for roll torque). However, as you start to lower one of these cars, the roll center starts to drop faster than the center of gravity, and the further you go the farther apart they get. In fact, much lower than 1" ride height and the roll center actually ends up below ground level, the front-to-rear roll coupling gets all wacky and the handling goes all to...stuff. This is why you hear folks say "don&#39;t lower your car lower than with the control arms level".

The only resolution for this is to relocate the control arm pickup points higher on the car, don&#39;t lower the car, or lower it and seriously restrict the geometry with teeth-rattling springs (and even then it doesn&#39;t work well).

So, any cars, such as the Hondas, that have multi-link control-arm system do not have this geometric restriction to such a degree and have much more flexibility to lower their car down to legal minimums...

BTW, I added a winky-thingy to my above post... - GA

[Bill Miller]

"spherical Bushings" (my new term for them)[/b]

Check the WCTC rules, it&#39;s already there! And while I&#39;m not advocating anyone have to use stock rubber bushings, every car does have it&#39;s warts, and if you can&#39;t lower the car to meet the 5" limit, due to suspension geometry restrictions, I&#39;d call that one of the warts.

[turboICE]

Greg, how does this differ largely from the 240SX?



I mean I didn&#39;t lower the car just because I physically could, I found improving lap times incrementally as I lowered.

I understand what you are saying as well as I can from books like Tune to Win, but I am pretty sure my LCA are beyond level, is it a more extreme effect on your application and the gives in the increasing spread of RC outweigh the gains in movement of the CG? By no means disagreeing or arguing about the detriment to you, trying to understand the result that differs from my expectation. Educate me.

[Greg Amy]

Greg, how does this differ largely from the 240SX?[/b]

Not much in basic design; that is a McPherson strut suspension. However, your geometry maybe be quite different (e.g., location and angle of links).

...I am pretty sure my LCA are beyond level, is it a more extreme effect on your application and the gives in the increasing spread of RC outweigh the gains in movement of the CG?[/b]

It all depends on the geometry. What&#39;s your rear suspension like? Is it multi-link? Is it possible that your rear suspension is able to compensate for the poor roll coupling up front and carry a lot of the load?

However, as a general rule, any production-based McPherson strut suspension will have the roll center descending faster than the CG once the control arms start going beyond level...and I&#39;ve got McP on all four corners...

[turboICE]

Yes, double wishbone rear. Sounds like your model is a more extreme example of negative McP effect than I had come across before.

[tom_sprecher]

I did not take the time to read every bit of this post, mainly because it&#39;s kind of boring. I think what Tristan was alluding to is what&#39;s the point you are trying to make? And who, besides yourself, are you trying to make it to? Basically, what are you trying to acheive and who will it benefit?

On the surface it appears to be a hugh waste of time and effort, but hey, it&#39;s a free country, knock yourself out.

And from my previous life in Formula I would think the difference in the two Prod rules is the word "adjustable".

Also I think that everyone involved in this thread would look at the argument in another light if they looked up "bushing" and "bearing" in Machinery&#39;s Handbook. Although it is not the GRC, it has been the standard reference book for mechanical engineers and designers since 1932.

Machinery&#39;s Handbook defines a bushing as a tooling component used for locating drill bits quickly. A bearing, on the other hand, is a machine element that allows movement between two parts. What you have been refering to as a bushing is know as a "plain bearing". Food for thought.

[Greg Amy]

"Sometimes you win, sometimes you lose, sometimes it rains. Think about that for a while." -- Ebby Calvin "Nuke" LaLoosh

[Z3_GoCar]

Not much in basic design; that is a McPherson strut suspension. However, your geometry maybe be quite different (e.g., location and angle of links).
It all depends on the geometry. What&#39;s your rear suspension like? Is it multi-link? Is it possible that your rear suspension is able to compensate for the poor roll coupling up front and carry a lot of the load?

However, as a general rule, any production-based McPherson strut suspension will have the roll center descending faster than the CG once the control arms start going beyond level...and I&#39;ve got McP on all four corners...
[/b]

Greg,

Instead of railing aginst spherical bearings, what you need is a better way to lower. I&#39;m sure you know about lowering spindles. Another option would be to lift the lower mounting point up, like a longer ball joint or even a spherical bearing with a longer tapered shaft to replace your stock ball joint. You won&#39;t even have to modify your stock lower arm, making it perfectly legal, and you get to keep better goemetry.

James

ps. I&#39;ve got McP struts on the front and trailing arms rear. The only stock adjustment on my car is front toe, so much for a perfromance alignment for stock class auto-crossing.