[PSk]

With the lowered roll center (not a good thing with this or a panhard or watts ) what spring rate are you going to use?

Why do you say this?

Pete

 

[Nader]

Is your mill the one that attaches to the 9.8.5 x 16 bench lathe? I have that lathe and have been thinking about getting one. How do you like it and would you buy another one? I've been able to do so many things with my lathe a mill could do so much more. Thanks for the great documentation of your top notch work!

Glad you're enjoying the thread, Gigem. Both my lathe and mill are stand-alone units. I like them, but if I had the space, I'd get bigger machines.

Have you test assembled this stuf in the chassis to see if it has clearance for your components behing the diff to clear the chassis box behind the diff?...

No, I haven't test-fitted anything yet, Richard. Currently, this is a faith-based project, and there will be praying involved before I wiggle under the car with sliding block pieces in hand. And I'm not even religious. Then again, do you think a pesky issue like obstructive sheet metal would ever stop builders like you and I?

Like the underrated Vanilla Ice once said: "If there's a problem, I'll solve it. (Check out the hook while my D.J. revolves it.)"

 

[Nader]

I found a few more H.P.

Speaking of problems, I had to take a break from the sliding block project to address an issue I found with my intake manifold. I had disassembled it to have my local head builder match the intake to the new spare head being built, and I discovered that it was undersized for my Weber 45 carbs. I don't know why I didn't notice this when I had the whole thing apart for "carburetor madness" last year.

Below are pics showing the size discrepancy behind the mounting blocks (see that big step?), how much material had to be removed as scribed by the blue layout ink, and finally a comparo between intake matched and unmatched orifices.

 

[Nader]

...With the lowered roll center (not a good thing with this or a panhard or watts ) what spring rate are you going to use?

I'm curious about this problem with the lowered roll center as well.

For rear spring rates, see my previous comment about faith-based race car development. If the race gods aren't listening to my prayers, at least rear springs are relatively cheap and easy to swap out.

 

[60sRacer]

I suspect it's just a typo from RJ.

The stock Alfa has a low roll center in front, which sometimes goes below the ground when the car is lowered. (This can be cured using the dropped spindles RJ makes). In the rear, the roll center is defined by the trunion pivot, which is pretty high. Overall, the car has a roll axis (the line connecting front and rear roll centers) that tilts steeply from front to back. On hard cornering, this transfers excessive weight to the outside front, as we all know, as well as lifting the inside rear. The sliding block, watts, or panhard links used in the rear all significantly lower the rear roll center.

The roll axis still tilts down, but much less, reducing the weight transfer and notably improving the car's handling.

Robert

 

[Nader]

Having never before had the occasion to remove the rubber isolator blocks from the intake manifold, I now discover that there were no gaskets between them and the manifold. What the H is going on here?!

I didn't have any extra gaskets on hand, and didn't want to delay reassembly to order parts, so I made some of my own. I had material left over from a sheet of custom-cut gasket for one of my race bike's engine side covers. I had that done about 10 years ago, but I never throw anything away. I used a carburetor gasket as a stencil.

While on the subject of gaskets, here's my experience using a gasket adhesive: Back when I reattached the intake manifold after the last time I melted the head (a year and a half ago), I used Gaskacinch adhesive to glue the gasket, both sides, between the intake manifold and the head. So when it came time to remove that manifold, it turned into a herculean task. There was a big freakin' Snap-On screwdriver, cheapass Harbor Freight prybar, and a lot of cursing involved. I really feared that I might crack the thing before taking it off. Even though it's a weak adhesive, there's a lot of surface area on that manifold to hold the glue, and it held on strong. I won't be gluing it together like that again. I wonder if the silicon-based gasket makers (Permatex) would be any worse.

Anyhoo, back to making gaskets. I can think of better things to do on a Saturday evening, but with a glass of cheap cab and in the company of my family, this was a satisfying projectina nonetheless.

 

[dezracer]

Thanks, Robert. I think I'm stuck somewhere between "Necessity is the mother of invention" and "Idle hands are a devil's workshop."

I've been reading up on plastics, trying to decide on what to use for the yoke's liners. Acetal (Delrin) is very tough, but UHMW (ultra high molecular weight) plastic is very slippery. A lower coefficient of friction is highly desirable in a sliding block set up, whose weak point was the binding of the bronze block against the yoke's steel wear plates. So I went ahead with slippery UHMW, and if it eventually disintegrates, I'll switch to Delrin.

Try impregnated cast nylon color is dark green very tuff but not brittle we use it in offroad racing as suspension bushings on said parts.

 

[Nader]

Try impregnated cast nylon color is dark green very tuff but not brittle we use it in offroad racing as suspension bushings on said parts.

You're using Nyloil? Interesting. I like its properties, but it's very expensive to get a piece thick enough for a 30 mm wide block. But getting it as cheaper thin sheets for the yoke's wear plates is an idea...

 

[Alex]

I've used PETP in the past and this is pretty hard wearing, as well as slippery, but there are other options out there now which are made to specific blends such as this Nylatron. I have always bought small rods and blocks of surplus stock, so I don't know what full retail prices would be nowadays.

BTW, is there not another way of bonding the liner onto the cast aluminium? I don't much like the thought of the heads of the machine screws snagging on the block when the inevitable wear happens.

Great project ..........

Alex.

 

[PSk]

I never use gasket sealant on the inlet manifold of any engine, unless I intend not to run a gasket at all.

Way too much sealant is used on this site, and others, when it is simply not required.
Pete

 

[Nader]

I've used PETP in the past and this is pretty hard wearing, as well as slippery, but there are other options out there now which are made to specific blends such as this Nylatron. I have always bought small rods and blocks of surplus stock, so I don't know what full retail prices would be nowadays.

BTW, is there not another way of bonding the liner onto the cast aluminium? I don't much like the thought of the heads of the machine screws snagging on the block when the inevitable wear happens.

Great project ..........

Alex.

Hi Alex. I'll have to look into some of those fancy Nylon formulations. My understanding was that some nylons absorb moisture, and being that I'm in the moistest part of the country, the resulting swollen dimensions may be more than what the close tolerances of the sliding block can handle.

As for attaching the liners to the yoke; the countersunk screw heads will more likely shave the sliding block with wear rather than dig in and snag. Not sure how to bond something slick like UHMW plastic to the alyoominium yoke. Maybe if I unlocked the secret of how Teflon is attached to a frying pan, I'll come up with something.

I never use gasket sealant on the inlet manifold of any engine, unless I intend not to run a gasket at all.

Way too much sealant is used on this site, and others, when it is simply not required.
Pete

Agreed! Using it is a lack of confidence in the mating surfaces, combined with overconfidence that the engine will never need to come apart again.

 

[Nader]

While buttoning up the intake, I thought there was some play in the Rube Goldberg-designed throttle bell crank that could use some tightening. To my surprise, that fat-headed hex screw takes a fractional size. Who puts that kind of arcane fastener on a metric car?! Luckily, I have a 40 year old set of fractional Allen wrenches for this kind of job.

 

[radamm]

Kinda looks like a Torx fastener to me....

 

[Nader]

Kinda looks like a Torx fastener to me....

Nope, just a slightly mangled fractional hex. Stupid fractional...

The engine is all buttoned up. For the first time since fabbing the new exhaust, I drove it kind of hard up and down our 50 yard driveway. It's loud and angry. But tonally good such that even the wife approves. Not sure about the neighbors (they have a Prius).

With that done, I turned my attention back to the sliding block. I put things into place, and was met with good and bad news.

Bad news: It won't fit unless I ditch the filler hole pin that carries the actual sliding block. This cast setup seems made for a plate with the sliding block pin more centrally located on the diff.

Good news: Once I make up another plate with a correctly located pin welded into place, it will fit beautifully as intended. I'll just cut down that Ti pin to become the world's best filler plug. Sniff.

So here's how it would look, except that the assembly is sitting about 2" low, and 2 cm to the left. The car is on jack stands, that bottle jack is just propping up the sliding block. Oh, and I still need to make that fore/aft stabilizing brace.

Sexy! (If you dig an old Alfa sporting an obscure racing part it really shouldn't have)

 

[Nader]

I needed to cut some steel plates for the sliding block brace, so it gave me a chance to use my new plasma cutter. I couldn't pass up a deal on this cheap Chinese unit. Colossal Tech! It was $250, which will pay for itself in one and half jobs considering that the water jet people have a $180/job minimum.

The action shot is me cutting .125" Ti plate. This one's for you, Richard. Ti has that characteristic super bright sparking action that I like. My wife took the picture, and I don't think she was expecting such a light show. I couldn't see her reaction through my welding helmet, but based on the sound of her scampering and cursing, I'd say that she about crapped herself. Sorry, hon.

I'm sloppy with the cuts, lots of dross. Like welding, this will need practice, including getting a feel for the necessary amperage and speed of cut.

 

[Nader]

I also did some trimming of the sliding block struts and their mounting pads, so they fit within the shock bracing brackets. That puts the yoke at the center of the differential instead of over the filler plug as I had mentioned earlier. I have to redo the plate and pin arrangement.

This picture is better at showing how the apparatus will fit. BTW, I really like that LED work light. Lots of light, no heat, and only 25W!

 

[Nader]

I was up all night, on call at the hospital, and came home for a 3 hour nap before resuming work on the car. It's probably not the best idea to do suspension work on a race car in a semi sleep deprived state. Who knows what horrors await me when I review the day's work tomorrow after getting some rest.

I laid under the car, on the concrete garage floor, and just stared at things. Almost fell asleep right there a few times. I was making decisions where pieces should go, where to drill holes and such. Despite my fatigue, I think I pulled it off and got the sliding block assembly mounted into place.

I didn't stink up the place too badly until I started welding up the brace that limits fore/aft movement of the sliding block's yoke. I got careless, welding without the helmet (but diverting my eyes from the arc), and caught some sparks in my hair. Burning hair stinks! I think I burned my scalp, too.

 

[Nader]

Made another pin for the sliding block. . I'm really impressed with the performance of the cheap unibit drills from Harbor Freight. I gave it a shot because I didn't have a conventional bit that big. Didn't really expect it to make a >1" hole in 1/4" steel plate, but there it is. Then I welded the pin into it from both sides. I'll weld this getup onto the adapter plate that's fitted on the differential.

Also welded on an additional plate to the yoke's bracket. Just odds and ends like that. Still need to grind and shape things, then paint them.

 

[Nader]

I've been racing the last few seasons on these 185 Hoosier Speedster tires (on 6X14" wheels). I've had 205 width Speedsters in plastic bags in my dark basement for the last couple years, waiting until I got 7X14" Panasport wheels in the Spider-correct offset (ET 17). These new/old tires still have that excellent pungent smell of fresh rubber. As far as motoring scents go, some people like the smell of gasoline, some like rain on hot asphalt. I like new tires. Look at all that extra rubber I've been depriving myself. All that extra traction...

These 7X14 wheels were hard to source. I've been harassing the nice lady at Spruell about them for the last 6 months, and it seems that this size is not available. As of a couple weeks ago, the US importer for Panasport knew of no future date for more batches in this size. I was on the verge of having custom wheels made for boocoo dollars. Pardon my French.

So when these popped up, I snagged them. 11.5 pounds apiece. Now that I got them, I'm sure there'll be a fresh batch of new wheels shipped to the States in the next week or two. I wasn't sure about keeping the gold powdercoat, I was planning to repaint them in black. But it's really growing on me. Hmm, I'm starting to think of a livery change...

 

[conedriver]

You will know if the new/old tires still have grip if you pick up OPR during your next track session. OPR: "Other Peoples Rubber"

... All that extra traction......

I really enjoy reading about your progress with the Spider.