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Pics of a Duetto racer buildup

197K views 809 replies 75 participants last post by  Alfar7 
#1 · (Edited)
Whew, I've been waiting a long time to start a thread like this. Though I'm not done, I've made enough progress to start the exhibition.

Okay, technically it's not a Duetto, but a '69 1750 Spider Veloce. I'm calling it a Duetto from here on out for convenience.

I bought this car 2.5 years ago locally from a lead off this site. I was looking for a wreck to rescue. This fit the bill almost perfectly: Banged up body, rusty floors, already stripped, and an unoriginal seized engine. It had most of it's ratty and moldy interior bits in boxes.

More importantly, it's a '69, which to me is the most desirable year Alfa we can run in our particular vintage race organization here in the Pacific Northwest.

If these pics upload properly, you'll see the car as I first saw it:
 

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#745 ·
As for the races themselves, I had a great time as always. Including my customary camping at the track. Lots of improvements were made to the landscaping around the course; removal of embankments, bigger runoff with gravel, etc. People who don't attend this event are missing out. My fellow Alfa racer and friend Tom commented that in the four years he's been racing with me, he doesn't recall me doing any engine work. He's right, and I hope he hasn't jinxed me.

Here I am in the trailer, enjoying a pickle between sessions.
 

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#746 ·
The race season ended uneventfully. I was surprised to learn that I got third place in my class for the season. Surprised because I was always midpack in the >2L medium bore group where I was assigned to race, and didn't realize I was still being scored for the <2L class. I was also surprised to see a small picture of me racing in our club's magazine.

There I was, running by myself, midpack in the medium bore group, exiting turn 9 to enter the straightaway at Pacific Raceway during one of the Fall Finale races. It was raining off and on that weekend, hence the dark clouds and sunlight. I think there was a rainbow at some point. Anyway, I liked the picture so much, I tracked down the photographer and bought the image. Here it is, taken by Bert McBride.

Formula libre Race car Race track Vehicle Endurance racing (motorsport)
 
#752 ·
Happy holidays.

Thinking about it, I've had two relatively minor recurring issues with the car.

One is the side dump exhaust with the megaphone cracking and falling off. I fixed that with beefier welds and better rubber mounting.

The other is failing alternators. I think I've mentioned it before. In one of my last races, the nut came off the alternator mounting bolt, and I lost the 10/12mm shouldered bolt. Must have been because of all the mounting and dismounting of failed alternators, and I probably under-torqued it last time. Anyway, by mid race, the alternator was hanging on by the tensioner. No alternator means no water pump. Discovered it when my radiator boiled over in a race and my temp needle got pegged. Luckily caught it before lasting damage was done. Luckily, @justcallmefred had a spare to loan me, and I was able to finish the weekend. Thanks again, Fred!

That bolt is a little tricky. It's 12mm through the engine bracket, then narrows down to 10mm for the alernator. And because of my setup with the mini alternator and oversized (underdrive) pulley, it can't be too long or it will grind against the pulley. I had to make one to replace the one I lost. If I'm going through the trouble to make a bolt, especially a big one, then by now you can guess how I'm going to it. Grade 5 titanium. If I'm making one, I might as well have two. Finally got around to doing it. Here's the process once again, starting with a couple of very nice longer-than-needed bolts, that needed to be shortened, then turned down and threaded on a lathe. Then finished by hand:

Titanium Metal Auto part Steel Screw


Machine tool Machine Tool and cutter grinder Tool accessory Milling


Clamp Machine tool Pipe Machine Valve
 
#753 ·
Finished product beside the other bolt that still needs cutting+threading. Also showing the piece of 10mm allthread I used to limp the car on and off the trailer after giving Fred back his bolt. Realistically could have used this hack indefinitely. Oh, and here's a small example of Ti wool I'm collecting. I now have multiple grocery bags full of this stuff. Just can't bring myself to throw it out. And finally an uninteresting picture of the bolt in its oily home. Engine bay is always this ugly by the end of the race season. I'll clean it next Spring.

Machine tool Machine Milling Tool Metalworking hand tool


Plant Metal


Auto part Metal Clutch Engine Automotive engine part
 
#756 ·
The stand-off brackets were for an earlier (crude) alternator installation but, as an alternative to safety wire, I still reverse the big bolt and double-nut it.
 

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#755 ·
Thanks, Pete. That's a good thought. My race bikes are extensively wire locked. But with cars, especially this situation, space is awfully tight for wire locking down there, especially from above. I always use anti-seize on all the titanium and stainless fasteners on my projects, but in this case, I'll probably just use blue thread-locker in addition to a locknut. Belt and suspenders setup. And since I know you're thinking it, there's not enough space under the nut end for a lock washer. And putting one under that beautifully flanged titanium bolt head would be barbaric.

Since I mentioned bikes, they'd get jealous if their pictures weren't included. Here's a front hub, locked down in wire. That's a titanium brake stay I made, go figure. And yes, there's a Gulf Blue race bike lurking in the background.

Land vehicle Vehicle Motor vehicle Automotive tire Tire


Tire Auto part Spoke Vehicle brake Wheel
 
#759 ·
hi nader ,,new member here to the forum ...have enjoyed reading your posts over the last 5 days ,,,well done you are a very talented gentleman ,,have inspired me to get onto my projects again after a long lay off ,,,thank you for your dedication to detail ,,regards mac
Thanks, Mac! I appreciate that. I, too, use other people's projects as inspiration for me to forge ahead with my own. I'm glad mine was able to do that for you.
 
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#763 ·
Thanks, Simon, for posting that. Keep in mind, I am in my little 1800cc 4 cylinder car doing my best to keep up with six cylinder 2.5L Porsches and Triumphs. The Bimmers are ridiculous, too.
 
#764 · (Edited)
I totally understand! There’s a reason I’m building a Datsun Roadster and not a 2002, GTV, 510 or anything else to run in that B-Sedan group . It’s not just the displacement you’re battling but the guys with deep enough pockets to squeeze all the power out of the motors that only need to last a seasons’ worth of hours. Those guys are usually in B-Sedan. I’ll happily battle the Alfa Spiders and the assortment of British cars.

That particular gent has made some wise choices in his life as he campaigns a pair of 2002s, a CSL, a Chevron and I believe just picked up a E30 M3 too... sigh...
 
#765 ·
It's been a minute.

Still at it, racing and developing the car. For the last few races, I had a new vibration. Discovered that my exhaust megaphone setup had cracked and dislodged its mount, so naturally thought it was that. Fixed it, but the vibration persisted. Also noticed at the season opener that my clutch was slipping. So when I dug in, I found this:

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I usually check my driveline every year or so, but somehow missed this. It had "Giubo Savers" which probably kept disaster at bay. Scary. So I decided to replace this with the beefier one from Spruell, as well as his Tilton clutch setup with the lighter flywheel.

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Here is the new giubo installed with the new retainers. Highly, highly recommend these.
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Here's a weight comparo between my old "hot" setup and new. Old one was an aluminum flywheel with aluminum Porsche Sachs pressure plate, which is NLA. New one is the Tilton setup.
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Installed

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I got this all installed just before the Historics race around the 4th of July. Much lower key event with lighter turnout because of the pandemic, but still fun. The two things I noticed from these modifications were a lack of vibration (stupid busted giubo!) and less engine braking from the lighter weight clutch/flywheel setup.
 
#768 ·
Yeah, I recall that beefy giubo being referred to as a "German flex disk." Oh, forgot the pic of the Tilton pressure plate installed, for completeness' sake:
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After that last race, feeling like I was running out of things to do to the car, I decided it was time for some aero improvement. I tried to make my own front spoiler out of aluminum angle and reinforced rubber sheet, but it came out sloppy. Really hard trying to make stiff materials follow compound curves.

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So I removed it, and bought a fiberglass air dam from Serpent Autosport. Here is the test-fitting. It's going to take some massaging, persuasion, and coercion (in that order) to make it fit. Anyone recognize my work shirt?

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Brought the air dam inside to measure it up for mounting holes to be drilled. We now have a Bengal kitten in the household. Unlike my previous German Shepherd (RIP, Baldor) who quietly observed my projects, this cat is a bit over-involved. He's a project deterrent. His name is Chef. He's a bit of a jerk.

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Ultimately, I got the holes measured out and drilled, and the air dam mounted. I like it, looks like the car put on another 20 lbs of muscle. Won't know until I hit the track again how it affects the car's handling. Also resprayed the nose block-off panels.

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#769 · (Edited)
Spruell does not sell this giubo anymore. But your photo gave us its identity: SGF GAD-136. It's a Mercedes donut, part number 2104110415.

It seems thinner than the original (46 mm). In another thread, there was a discussion about a German donut causing vibrations. In the end, it was solved by shimming the new, thinner donut so its center would fall at the same place as the center of the original donut (the shims would be half the thickness difference). This coincides with the contact point between the olive on the input shaft and of the pilot bearing.
 
#770 ·
I was wondering why there are more threads showing above the 19mm locknuts, it's thinner! Interesting on the centers being in the same plane.
 
#771 ·
We can see some thick spacers between the front propshaft and the giubo. The difference in thickness is 46 - 32 = 14 mm, so the spacers should be about 7 mm each side. This looks like it could be correct, hoping there is an equivalent spacer between the output fork and the giubo.

We'll ask Chef to check.
 
#772 ·
Chef doesn’t know squat. I wouldn’t ask him anything. Besides, he’s a bit of a jerk. Will probably give you wrong information on purpose.

I can confirm that you are correct about the spacers, and they are on both sides of the flex desk.
 
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