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Discussion Starter #603
Fun with plastics

I was going to make a block (for this sliding block contraption) out of metal, bronze or titanium with delrin inserts, but I kept making more out of plastic. Specifically, nylon. I got a lifetime supply of Nylatron GS. It's a tough nylon formulation infused with molybdenum disulfide to improve its lubricity. A bit stronger than Delrin, but like most Nylons, it's susceptible to absorbing moisture and swelling slightly. Maybe about 2%.

That's about $300 worth of it, but I found it for $40. Fun to machine when you're used to wrestling/coaxing Ti. My tools just power right through the stuff.
 

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Discussion Starter #604
Nylon madness!

A few posts back, someone suggested using the oil-infused green Nylon. It's called Nylatron LIG. I found some, and thought "What the hey!" Let's keep this nylon train rolling!

Check it out: Neapolitan sliding blocks, served on a thick plate of titanium. Yum!
 

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I'll be interested is seeing some driving test results of these plastic blocks. Cornering loads are pretty hard, and a long race is quite a test.

Robert
 

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Discussion Starter #606
Yeah, I'm curious (and a little anxious), too. I just won't know until I get out there. I'm going to have to take it really slow and watch things closely before pushing it. Maybe pull in after the first couple laps to see how things are wearing. I'm going to take the trunnion arm to the track as well and swap it in if there's any problem. That's my Plan B.

This whole sliding block madness has given me "project fatigue," so I think I'm done messing with things for a while. Except for one last bit; the seat mounts.

The local race shop fabs these, and I like to support them when I can. They're made pretty stoutly of alyoominium, and I didn't expect them to be this much lighter than the steel ones that came with my seat.
 

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Discussion Starter #607
Racing the season is upon us! For me, it starts with motorcycles. I'm doing that this weekend, and will be racing the car next weekend.

The race bike takes a different line than the car, and although it will screw me up a little for the first couple of laps in the car next weekend, it's still nice to get out and reorient myself with the race track. I've already discovered, in a couple of scary moments, that the pavement is coming apart in Turn 3. That's a bigger deal on a motorcycle than it is in the car, for obvious reasons.

My motorcycle racing campaign has taken a backseat to the car project for the last couple of years. I almost forgot how much fun this is. And cheaper, too. Entry fees are one third that of cars.
 

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A few posts back, someone suggested using the oil-infused green Nylon. It's called Nylatron LIG. I found some, and thought "What the hey!" Let's keep this nylon train rolling!

Check it out: Neapolitan sliding blocks, served on a thick plate of titanium. Yum!
that was me ,delrin is good stuff but it brinels steel in my applications in offroad racing .
 

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Discussion Starter #609
that was me ,delrin is good stuff but it brinels steel in my applications in offroad racing .
Ah, yes, Dez, thanks for that! The Nylatron LIG (or Nyloil) worked excellently in my first race of the season. I'll report on that shortly.

But first, here's something I found symbolic. I was towing the race car to the track for the first race of the season (you can see the reflection in the sideview mirror) when I saw someone's discarded necktie in the middle of the road. I imagine some angry son-of-a-gun stripped that thing off and chucked it out his window, yelling "Take this job and shove it!"

I applaud you, sir. Now let's get to the track, burn some $10/gallon leaded fuel, and try not to kill ourselves with an untested homebrew suspension setup.
 

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Discussion Starter #610
Double guns!

I hadn't noticed it at first, but that picture above captured the historic Wilburton Trestle in the sideview mirror.

So, first race weekend was a success. The car is a lot faster! Too many variables to know what was most responsible for the improvement.

Porting the intake manifold and shortening/reconfiguring the exhaust to a sidedump megaphone definitely improved power, because I am now able to reach redline in 5th gear by the end of the straight (despite increased rolling and wind resistance from the wider tires).

The car handled beautifully in the turns! Some of that may be improved traction from the wider 3 year old Hoosier Speedsters that I finally put to use on the wider Panasports. But I've had Speedster 205s on my old 6" rims in the past, and never went around turns this well before. It's hard to put into words, I'd say the car feels more stable, balanced, and confident in the hairpins, sweeper, carousel, and transitions through the snake bends. The car has always been very forgiving and neutral with a very slight bias to oversteer, and now feels even more planted in all turns.

No clunking, binding, or noticeable wear of the Nylatron sliding block (thanks again, Dez).

The differential trailing arm didn't punch through or even bend the rear bulkhead sheetmetal (I didn't brace it any further than what I've already shown).

In summary, the changes yielded a consistent ~2.5 second drop in lap times. It's enough to get by most of the Triumph TRs, and to keep the Porsche 356s in sight. The mildly unfortunate tradeoff for the improved performance is that I'm racing alone in a gap between the front runners and the middle pack. But that's okay, it gives me reason to find more improvements to close that gap.

This is a REALLY cheezy pic, but I can't resist. I'll probably pay for this boastful attitude later...
(Man, that cage is tall!)
 

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Discussion Starter #611
Yeah, that last picture is going to invite trouble. I need to balance happy with sad, so behold my last dyno chart.

The only change to the engine since that pull was that porting of the intake manifold and the new exhaust. I know, there is a wide variation in dyno readings, didn't wind out the engine, blah blah blah. Still...
 

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In spite of your "attitude" in that last picture, you have one of the coolest/cleanest looking race cars of any make/model/year or type I have every seen. Wish I could hear/watch it run, tall bar or not...:wink2:
Have a spectacular season Nader and all the best!
 

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Discussion Starter #613
Thanks for the kind words, Bill. If I ever have a chance to race at Circuit of the Americas, I'll give you a heads up. OTOH, if you're ever in the PNW during a race weekend, shoot me a note and I'll put you on my crew list to get in to the races for free.

Yeah, double guns above is a bit much. Single gun would have sufficed. I couldn't help it, I was relieved of anxiety, overjoyed with results, and my Alfa cup runneth over. At least I had sense enough not to wink with the guns.
 

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Wow. 2.5 sec drop on your first outing is really something. Congratulations!!

Of course you know there's more in there. I found the sliding block such a dramatic improvement in full-power corner exits that it took me a lot of practice to find the 10/10ths edge. It was WAAAAY past where I was used to.


IF you're not kicking dirt occasionally, you're not at 10/10ths yet......
Go for it!!

Robert
 

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Discussion Starter #615
Robert, you're exactly right, and you sound just like my older brother (crew chief) who kept encouraging/goading me into using more of what I had this last weekend.

The car doesn't slide as much, and I'm not using as much of the track as I should. Whereas before I would guide the car through the turns calmly with grim determination, I now grunt in exertion against the rising lateral forces, and grimace with the fear of unexpectedly fast cornering speeds. I have more to learn.

All because of this:
 

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Richard Jemison
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That roll cage!

With that much room between your helmit and the top of the roll cage, If you are concerned with head protection, you should go to weight watchers and kidnap a fat woman and duct tape her between your head and the top roll bar. Maybe Gorilla tape would be stronger.

Why byuld trinkets with titanium when you have 40 lbs of un-necessary tubing in that tall ugly rollbar?
 

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Discussion Starter #617
40 lbs? Are you drunk? If I sectioned out 4" of tube from each side of the main hoop, what would that weigh?
 

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Ah! Roll bars! In the early days of SCCA, a roll bar was more cute than functional. Today, the simplest "broom handle" test is hard enough - without a full Duetto windshield, the top of his roll bar has to be pretty high, as the front end of the broom handle rests on the car's hood. They sure are ugly compared to the svelt things we drove in the 60's. I always thought it was so hard to flip a Duetto that you really didn't need one at all......

But I raced bicycles without any helmet back then too.

>:)

Robert
 

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Discussion Starter #619
With that much room between your helmit and the top of the roll cage, If you are concerned with head protection, you should go to weight watchers and kidnap a fat woman and duct tape her between your head and the top roll bar. Maybe Gorilla tape would be stronger.

Why byuld trinkets with titanium when you have 40 lbs of un-necessary tubing in that tall ugly rollbar?
On second thought, I'm going to give you a pass on this, Richard. The awkward attempt at humor, outlandish weight claims, and multiple typos suggest you're not in your right mind.
 
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