Thread: Project Sebring GT Spyder

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Originally Posted by Hotrod46

Thanks. I didn't know about that site. I keep an eye on it.

I've bought a number of parts off Racing Junk, no problems with anything from there but I like to research the seller before making any deals! Over the years I bought a couple "N" center sections off the site, along with a Doug Nash 5 speed for parts. Just like any other site, it's still a "buyer beware" place, but when you know what you're looking for and how to confirm the parts being sold match the description it seems to be as trustworthy as any of them!

Here are a few more pictures of the Cobra SVT brake conversion I did. I started out with a fabricated two piece steel bracket that was bolted together, but eventually carved one piece brackets out of 6061 aluminum. The new brackets weigh about half of what the steel ones did.











I think I should mention that it probably looks like I have the rotors on the wrong side. All of the slotted rotors I’ve seen have the slots slanting backwards at the top. However, I’m running Baer brakes in the front and they have directional, curved vane rotors with slots. Baer has the slots slanting forward at the top. Even though the rotors where clearly marked right and left, it looked different enough to make me question whether it was right. I looked at a Baer produced installation video and they make it a point to say that the forward slant is correct for their rotors. Since the rear rotors I’m using have non-directional vanes, I decided to swap them around to match the fronts.

I just recently found out that Baer makes a rear disc kit that appears to be basically the same thing I built! I originally got the idea from a Mustang site. They were talking upgrading Mustang brakes and it sounded good, but the SVT caliper brackets wouldn’t fit on the Explorer axle I was using then. So, I came up with my own brackets. Interesting to me that Baer felt it was a good enough upgrade to sell it under their name. That also explains why their tech knew exactly which master cylinder to recommend when I told him I was using SVT brakes.

J. Robinson, on his ’32 build thread, recently commented about how fabricators that build off the top of their head, often make problems for themselves that don’t show up right away. Well, that’s the same way I build, no drawings, just an idea in my head and I sometimes have those same types of issues. I ran into one while reassembling the rear suspension.

During the thrash to get the chassis to powder coat, I realized after I had the rear suspension torn down that I had forgotten to do the rear shock mounts. No problem, I thought, I’ll just measure and “quesstimate” where they should go. Well, I missed it by about a half an inch. I didn’t have the actual shocks I was going to use and went by an old pair I had under the bench. Bad idea and the new shocks were going to be too close to the Watts link mounts.

I came up with a few fixes. One, I could cut the existing mount off and move it, but that would have destroyed a large section of nice powder coat. I had them welded on very well.

Two, I could move the shocks to the rear of the mount and just run them in single shear. That might have worked if I had built the mount heavier, but I didn’t. It just had 3/16” thick ears and with the shock mounted behind, it put most of the load on a single ear, even if I tied the mount together with a spacer. Not good enough for me since the upper mount will be hidden when the body goes back on. Inspecting it will be difficult and I wanted to make sure it didn't fail.

The solution I went with was to move the shocks to the rear of the mount and add a third, bolt-on ear to put the mount back in double shear.

I started out locating and drilling 3/8” holes through the frame. This is how I make sure that I keep stuff like this square. I take an old piece of tubing or sometimes wood and drill a hole square to the surface. I clamp that on and use it as a drill guide. Works pretty good and is way better than trying to free hand that hole on the other side of the tubing.



I made some crush sleeves and welded them in. This was just a “fusion” weld and took minimal heat.










After a lick of paint, it was almost like it never even happened.





Here is the finished fix.

I've worked with some of the best engineers and designers, they have fixes too! Nice job!!

Good save Mike.

A great idea, great approach and great execution! Triple win!

That's clever.

Thanks guys.

Nice thinking, I've done a lot of cutting and welding on my frame since it was " finished ". A little paint you forget all about it .

After repairing the upper shock mounts, I needed lower mounts to match. These didn’t pose the problem that the uppers did, since I hadn’t built them yet. That was a stroke of luck since they had to be farther back to match the uppers.

Because they had to be so far behind the axle, mounting them in double shear would have taken a lot of bracing. I decided to mount these in single shear and just build them heavy enough to take the load.

The mounts wrap around and bolt to the lower link brackets. The main 5/8” bolts that hold the links also go through the shock mounts. This way as long as the links are attached, the shock mounts are too. A couple of 3/8” grade 8 bolts also go through the rear to stabilize them and allow moving the link position without the mounts coming off.

The mounts themselves are machined from solid bar with a 5/8” threads. I’m using a bolt right now but may swap over to a stud for maximum thread support. I counterbored the threads so that the weight will be supported by the full diameter of the unthreaded portion of the bolt and not just flexing on the root of the threads.
The mounts are a little longer than I wanted, but that’s the way it goes sometimes.

The shocks are gas filled parts by Ride Tech with a little over 6” of travel. The gas charge is why they are able to be mounted upside down. This reduces unsprung weight a little and allows easier access to the rebound adjustment. It would be very difficult to reach if they were mounted the other way.


The shortened tap is what you do on a Sunday afternoon when you don’t have a bottoming tap, but you have two taper taps.

Originally Posted by Hotrod46

The shortened tap is what you do on a Sunday afternoon when you don’t have a bottoming tap, but you have two taper taps.

I do it because I'm cheap and can, been doing for so long I now have a whole set of bottom taps. LOL!

Or if you snap the end off a tap: voila, it's a perfect candidate to become a bottoming tap! Just grind it down, you'll use it eventually.

During the redo, I changed the way the Watts link brackets attached. This is how they looked originally.



I pulled them in closer to the axle tubes and raised them. The old system was more adjustable, but that adjustment wasn’t really usable if you ran the exhaust out the back of the car. The new setup had to have link bars with a dogleg in them. Building these wasn’t an issue now that I have a decent tubing bender. The left link was fairly simple, but the right link had to go over the exhaust pipe. While they look radically different, they both hit the same points in space. I built a temporary jig off of the left link and used that to build the right link. Because of the dogleg, the pivot on one end had to be non-swiveling, otherwise the link would just flop around, but it also needed to be able to move forward and back as the axle moved. For that, I used some Energy Suspension universal poly bushings and installed grease fittings. The other end uses heim joints. The Watts rocker (or propeller) is the same.





The new axle brackets



I have several poly bushings on this car and I’m fitting all of them with grease zerks. I bought a new grease gun that I filled with silicone grease with PTFE (Teflon). This stuff is called Super Grease and looks exactly like the grease that comes with most ploy bushings. Hopefully, by being able to give them a shot of grease occasionally, I can keep them moving free and avoid the poly bushing groan and moan. Here’s a link to the manufacturer’s page:

https://www.super-lube.com/silicone-...-syncolon-ptfe

I’m going to use this grease to lube the carb linkage that I built, too. It’s got a broad temp range and is supposed to be virtually impervious to water. It comes in standard 14 oz grease gun tubes.

The lower axle links changed, too. I moved the auxiliary air bags from the rearend to the lower link. The air bags are just for extra load carrying. Since I intend to do some long distance trips in this car, I will never know exactly how much weight I will be hauling. I have right at 3” of suspension travel in both directions, but I don’t want to use any of it up when loaded. The coilovers will still do most of the work. The air bags only come into play when the car is loaded. I will adjust the coilovers for a small amount of rear sag with no air. This will insure that the bags always have a little air in them to prevent them from being pinched. This is the way that GM and some other manufacturers did their supplemental air suspension. Because the lower links will be carrying some side loading, I built them out of heavier wall 1 ½” tubing. The bags are Firestone 7012’s, They will carry 1000 lbs each at 100 PSI. Mounted like they are, the shocks stop them from over extending and the frame bump stops keep them from compressing too far.









The front joint on the lower links is a Ride Tech R-joint. This is a little smaller than the Spohn joints I was using. I made this change because I had to cut some off the bottom of the front link mounts. After I lowered the car, they hung down too far. I shortened them one inch. The smaller R-joint allowed me to keep most of the original adjustment that I had built in. The axle end of the link has poly bushings. Like the Watts links, it had to have a non-swiveling bushing to keep it from turning.





Mounting the bags on the links actually reduces the unsprung weight a small amount.

The air suspension will be auto leveling. I am using a GM level sensor. These came on luxury cars from the 70’s up through the 90’s and they are a little bigger than a pack of cigarettes. The nice thing about them is that they are pretty much a stand alone deal. All of the electronics are in the case with the sensor. A couple of relays, a small compressor and some small solenoid valves are all you need extra. There is no air tank. The compressor just adds air straight to the bags when it’s needed. I used this same system on my T-bucket for almost 10 years with no issues. That car used the bags only with no other springs.

The compressor is a Viar 100, which is a motorcycle size unit. The valves are 1/8” industrial control valves. 1/8” is plenty big enough for this system. My intent is to hard pipe the valves to the bag inlets. This is the way my T was done and it could sit for days without leaking down very much.

This is the sensor on the car. All the crazy arrows are there so I can keep up with up and down. The sensor will work in a couple of positions, but there is a correct orientation. The control scheme opens the down valve for a few seconds before starting the compressor so that the compressor doesn’t have to start under load. So, the sensor has to be installed right or the operation will be backwards. I learned this the hard way on my T.