Pics of a Duetto racer buildup - Page 41 - Alfa Romeo Bulletin Board & Forums
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post #601 of 764 (permalink) Old 03-09-2015, 06:40 PM
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Saw this video just now and the first thing I thought of was your rollcage, Nader.


Chris

1990 Spider Veloce
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post #602 of 764 (permalink) Old 03-09-2015, 08:14 PM
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Roll cage

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Saw this video just now and the first thing I thought of was your rollcage, Nader.
Probably would have sheared off.... Too tall.....

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post #603 of 764 (permalink) Old 04-02-2015, 12:43 PM Thread Starter
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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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post #604 of 764 (permalink) Old 04-02-2015, 12:49 PM Thread Starter
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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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post #605 of 764 (permalink) Old 04-02-2015, 02:16 PM
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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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post #606 of 764 (permalink) Old 04-02-2015, 04:09 PM Thread Starter
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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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post #607 of 764 (permalink) Old 04-25-2015, 07:44 PM Thread Starter
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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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post #608 of 764 (permalink) Old 04-26-2015, 01:27 PM
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Quote:
Originally Posted by Nader View Post
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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post #609 of 764 (permalink) Old 05-03-2015, 09:29 PM Thread Starter
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Quote:
Originally Posted by dezracer View Post
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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post #610 of 764 (permalink) Old 05-04-2015, 12:05 PM Thread Starter
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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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post #611 of 764 (permalink) Old 05-04-2015, 12:44 PM Thread Starter
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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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post #612 of 764 (permalink) Old 05-04-2015, 01:20 PM
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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...
Have a spectacular season Nader and all the best!

Get out there and [B][SIZE="4"]DRIVE ![/SIZE][/B]

Bill ("Plays well with others")
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Last edited by Bill; 05-04-2015 at 01:21 PM. Reason: spelling
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post #613 of 764 (permalink) Old 05-04-2015, 04:54 PM Thread Starter
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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.

69 Spider, 2L, street; pursuit of happiness
69 Spider, 1.8L, race; happiness of pursuit
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post #614 of 764 (permalink) Old 05-04-2015, 05:03 PM
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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!!

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post #615 of 764 (permalink) Old 05-04-2015, 05:37 PM Thread Starter
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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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