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Old 05-08-2013, 12:49 PM   #21
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How did you get that much with stock arms. did you make some modifications to something?
Prototype offset Delrin bushings. The production pieces will be a much lower cost acetal with better lubricity than Delrin. Maybe 8 weeks out for the first batch.
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Old 05-08-2013, 02:56 PM   #22
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Prototype offset Delrin bushings. The production pieces will be a much lower cost acetal with better lubricity than Delrin. Maybe 8 weeks out for the first batch.
Orly ...
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Old 05-08-2013, 03:24 PM   #23
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what power level constitutes a high power car where less camber starts becoming a setup factor?
The way your question is stated infers that at some power level camber is not "a set up factor" whatever that means. Camber is one of many adjustments that should be optimized to get the most from your tires regardless of power.

Up to you to determine what camber your particular set up, power and conditions want. Get a pyrometer, consistent driver and lap timer. Report back
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Old 05-08-2013, 03:48 PM   #24
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Prototype offset Delrin bushings. The production pieces will be a much lower cost acetal with better lubricity than Delrin. Maybe 8 weeks out for the first batch.
One of the reasons I swapped arms besides the added adjustability and the ability to adjust camber independently of the tow, thrust angles, and caster was the urethane bushings in my old arms basically stopped pivoting. I needed to do something anyway. Urethane bushing just plain suck I dont care what tricks you try to keep them functioning properly. The friction characteristics of urethane to slide around a steel pivot pin just sucks and grease of any kind will not stay in the proper place or effective for very long. When it takes 40 lbs. of force or more to get the arm to pivot the suspension sucks no matter how much money you put into shocks.

I was cussing at how much friction there was in the urethane bushings in the V8 roadster arms when I was installing them. I was hoping they would be much better than they are. Then I figured out most of the joints pivoted better if I greased every surface and they slid inside the arms instead of around the center pins. This got the friction down to just a few pounds. No telling how long it will last or until the mix of antiseize and redline grease I used turns to dirt though and everything will need to be taken apart again to get grease in effective places.

Id like to find real bushings that fit the V8 roadster arms instead of the stupid material choice urethane ones they came with.
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Old 05-09-2013, 10:40 AM   #25
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Prototype offset Delrin bushings. The production pieces will be a much lower cost acetal with better lubricity than Delrin. Maybe 8 weeks out for the first batch.
I'm confused, Delrin is just Dupont's TM name for Acetal. And better lubricity, I'm guessing you're going to PTFE impregnated Acetal. If that ends up being too soft we picked up some glass reinforced PTFE Acetal in the shop that is the ****.


Bob, your V8R arms have poly? I swear the only set of them that I've seen had delrin, and the owner of the car claims that every bushing in the car is delrin, even the steering rack.
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Old 05-09-2013, 12:18 PM   #26
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I'm confused, Delrin is just Dupont's TM name for Acetal. And better lubricity, I'm guessing you're going to PTFE impregnated Acetal. If that ends up being too soft we picked up some glass reinforced PTFE Acetal in the shop that is the ****..
The protos were made a long time ago from Delrin. I began experimenting with camber up to 4* about a year and a half ago. Pleased with the results, I decided to put the bushings into production this year. The engineer working on the project suggested a non branded acetal that would be both better suited and way less expensive. The formulation will remain proprietary of course.
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Old 05-09-2013, 12:25 PM   #27
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Of course. And it make sense to go non-branded, they price of plastics seems to vary wildly based on distributor even when you know the stuff is coming out of the same batch from the same plant.
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Old 05-09-2013, 10:54 PM   #28
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Bob, your V8R arms have poly? I swear the only set of them that I've seen had delrin, and the owner of the car claims that every bushing in the car is delrin, even the steering rack.
Propriatary 95A poly and just as crummy of a pivoting bushing material as any other poly byshings I have experienced.

In My opinion if a person wants stiffer A-arm bushings they should go straight to Delrin or acetal or whatever. The car rides better on A-arms that pivot more freely allowing the shocks and springs to do there job much more so than having just a miniscule amount more if radial vibration damping over real bushings. Poly is good for locations that donít need low amounts of sliding friction like engine mounts, diff mounts etc not for bushing where low sliding friction is what is really needed.
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Old 05-09-2013, 11:29 PM   #29
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I never hear anyone talk about UHMW as a viable bushing material. UHMW is dirt cheap and has a friction coefficient close to Teflon.

Does it have some quality that makes it unsuitable as an A-arm Bushing?
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Old 05-10-2013, 12:07 AM   #30
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I never hear anyone talk about UHMW as a viable bushing material. UHMW is dirt cheap and has a friction coefficient close to Teflon.

Does it have some quality that makes it unsuitable as an A-arm Bushing?
It costs more than acetal and is a pain in the butt to machine in comparison. And it has about half the strength of acetal.
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Old 05-10-2013, 02:50 PM   #31
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Prototype offset Delrin bushings. The production pieces will be a much lower cost acetal with better lubricity than Delrin. Maybe 8 weeks out for the first batch.
That sounds very temping. I've been considering this kit but I'd rather buy one from you. It would be even better if you could make it an option in the "big grip kit"
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Old 05-10-2013, 07:23 PM   #32
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I would think that large amounts of front camber would create a sub-optimal situation for braking, much like accelerating does for the rear in a high-horse car. Is the difference made up by braking less and cornering faster? Or is cornering that much more important to laptimes than optimal braking?
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Old 05-10-2013, 07:25 PM   #33
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I would think that large amounts of front camber would create a sub-optimal situation for braking, much like accelerating does for the rear in a high-horse car. Is the difference made up by braking less and cornering faster? Or is cornering that much more important to laptimes than optimal braking?
Calculate ratio of time spent turning vs time spent decelerating during a typical road course lap for your answer.
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Old 05-11-2013, 04:32 AM   #34
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Plus, you load the front tires so much with the weight transfer under braking. You're never going to load the rear tires anywhere near as much with acceleration out of a turn, so acceleration grip is much more camber sensitive than braking grip.

-Ryan
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Old 05-11-2013, 01:17 PM   #35
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E, what temp spread do you get across the tire @ 3.5-4 degrees camber?
I had Creampuff set at 3.6 for a few events last year, the pyrometer and my SOTP feel did not agree with each other entirely...
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Old 05-11-2013, 11:30 PM   #36
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E, what temp spread do you get across the tire @ 3.5-4 degrees camber?
I had Creampuff set at 3.6 for a few events last year, the pyrometer and my SOTP feel did not agree with each other entirely...
I find most DOT race tires, on the loaded side of the car (lefts on cw course), generate their peak grip with a spread of 15-20* or so.
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