jim lockwood

Check out the latest issue of "The Corvette Restorer". Sam Kalmuk describes the building of his Grand Sport.

It was 11 years ago I finished my #80 Grand Sport and I don't think too often about how much work and expense went into building that car. Sam's article brought all those (painful?) memories back!

It's a good article. Ya oughta read it!


Jim

Shultzie

This weekend in Kendallville, In. Sorry that's the only pics.

jim lockwood

GS Gang,

Many/most of you know I've created big brake packages for our two Grand Sports. They fit within the confines of the 15" PSE wheels and yet they will endure the rigors of road racing.

All of the special pieces needed for my brake package were one-off, custom parts that were, frankly, a PITA to produce.

However....

The owner of the machine shop where I had the parts made showed me today his brand new CNC machine and he specifically mentioned the brake parts. He indicated he could crank out more very easily if there were a need for any.

Well is there?

To refresh everyone's memory, here are a couple of pictures of the package for the early C4 suspension:







The brake package consists of:

1. C5 aluminum calipers
2. Custom caliper adapters
3. Modified Cadillac rotors: 1.25" wide, 64 cooling vanes
4. Attaching hardware
5. KO drive pins
6. Spacer
7. Wheel studs


If anyone has an interest in having a duplicate of my big brake package for the early suspension, let me know. No, I don't know what it would cost, but rest assured it'd be reasonable and it would depend on how many packages need to be created.

Jim

Mr. Wizzard

Dang Jim! Neither of us has good timing....
You can count me in on a set of the parts. I may not need them right now, but somewhere down the line may be a different story...
Larry

keystonefarm

Yes Jim you have very poor timing !!!!! I would also be interested in a set or maybe two !!! --------------Ken

jim lockwood

Yeah, I confess, guilty as charged in regards to timing. But how was I to know my favorite machine shop was going to join the late 20th century (now ended) and purchase actual CNC equipment??? And it was the shop owner who brought up the subject of the brake parts, not me (in case that buys me any sympathy).

Step 1 in this process is going to be me digging out the engineering drawings I made when I was designing all the bits and pieces. Yep, I've got drawings for everything. I need to re-familiarize myself with what I did though (remember, this was 5 years ago).

While I'm doing that, let me suggest you look around for a source of C5 calipers. You can probably find them just as cheaply as I can. Other than some possible minor trimming of the fins, the C5 calipers are used in as-received condition.

Step 2 will be that I'll take my drawings to the shop and get a quote on the pieces. But I'll wait until we know how many sets of parts we need first.

Jim

tyoneal

Boy those are Beutifulllll.

If they are available in the future I would not be opposed to upgraded Brakes. I've never regretted doing that kind of upgrade on any car either.

I would like to have some time to get my car finished and get some miles on her first.

Very very nice.

Any kind of a price estimate?

Ty

silverslashstreak

Hello Jim,
I would be interested for sure, but our roadster uses late suspension pieces and I am waiting until the body is back on frame to decide what wheel package I am going to use.
I am glad to know that option is going to be out there. Those rotors look awesome.

Jeff

jim lockwood

Thanks Jeff. The rotor/caliper/brake pad combination I have on our two Grand Sports has, all modesty aside, performed phenomenally well for us. We've never ever had a brake issue and, with the light weight of our cars, we discovered we could always out brake everyone else. We could wait an extra beat to begin braking for a turn and, in doing so, easily pass under braking.

My #80 Grand Sport has the late suspension, like your roadster. Adapting the C5 calipers and Cadillac rotors to it was an entirely different problem from adapting these parts to the early suspension. However it was a far simpler problem. As you can see from the picture below, it's almost (but only almost) a bolt on. Note there is no caliper adapter:



Although I remember what I did to put the C5 calipers on my #80 GS, I didn't document the project very well.... certainly not as well as I documented the package for the early suspension. I'd be starting almost from scratch to do another one.

Jim

jim lockwood

Hi Ty. Thanks!

No price estimate yet. I'm still re-familiarizing myself with what I did for our GS with the early suspension and extrapolating to what will be required for everyone else with early suspension on their GS (it will be slightly different and I'll explain the differences in another posting).

This is going to be a one-shot opportunity. I don't expect to go into volume production of these big brake packages. So if you want one, you'll need to be all-in with everyone else.

Stay tuned. More details soon....

Jim

jim lockwood

I'm going to need some information from those of you who want the big brake package. To make what I need to know make sense, let me explain a little about the architecture of this brake system.

To begin, the "stack up" of components is different from what you are used to seeing:



Note that the knock off adapter bolts directly to the bearing hub. This means that the rotor now slips over the KO adapter rather than being held captive by the adapter as on your cars now:



The reason for this unusual arrangement is to make the rotor and the caliper align properly. The caliper adapter has some thickness to it and that thickness necessitates moving the rotor outboard slightly. Well, it turned out that I could re-locate the rotor outboard without increasing the front track by simply changing the assembly order from:

Hub, rotor, KO adapter

to

Hub, KO adapter, rotor

Makes sense?

OK, sooooo this means the dimensions of the KO adapter now matter regarding making the rotor and caliper align properly. And that brings me to the dimensions I need from each of you.

I assume that everyone has the "Trigo" style KO adapters like seen in this photo:



Assuming so, I need to know the following three dimensions:

1. The thickness of the mounting flange (probably .375, but I need you to verify this)

2. The distance from the mounting plane to the top of the spinner threads (NOT to the overall top of the adapter)

3. The exact diameter (to within .001") of the large, unthreaded portion of the adapter, just above the mounting flange

Any questions? Just ask....

Jim

keystonefarm

Jim a question. My D&D 049 has bolt on wheels . Would your setup work with them ? The new Mongoose does have the Trigo K/O's ---------------Ken

jim lockwood

Hmmmmmmm...... Not without some modification.

The rotor must be properly centered within the caliper and it wouldn't be without the KO adapter present. I can think of two ways to compensate for the lack of the KO adapter:

1. Place a spacer between the rotor and the hub.

2. Buy a Wilwood rotor and a very short, nearly flat "hat" section.

I can tell you the dimensions of the required spacer and you could have one machined. I wouldn't have a clue what Wilwood pieces you'd need.

Jim

Edit: Been thinking about this some more. I don't think my system would work with bolt on wheels and a shallow rotor hat. Caliper and wheel would contact each other. Only the rotor with a spacer is likely to clear.

jim lockwood

For those of you contemplating my big brake system, here is a list of the GM-sourced parts you'll need to locate. Part numbers are GM numbers. Prices might be a little out of date; they are 12 years old. The pads are street pads. For competition use, you'll want something else.



Jim

jim lockwood

And as long as I'm blathering away today, here's a very short story:

We had a youngster, 20 maybe, doing some work around the house today. When he finished, my bride suggested I give him "the barn tour"... that's the barn where we keep our rolling stock.

I threw open the door and when he caught sight of our D&D his jaw just dropped.

After he recovered he said, "They built only five of these and they are worth millions. This one is a replica.............right???????"


Yep, I gave him a ride.

Jim

silverslashstreak

Great story Jim, I Bet you made a corvette lover out if that kid for life!
Jeff

NW-99SS

Great story indeed!! Always nice to meet the guys that know their GS history

My GS question goes to the Mongoose crowd...

I recently traded into my Mongoose GS, and was told it is the only Mongoose GS in Canada. The builder has rights to sell/build all Mongoose cars in Canada and he says it's number 1 up here in the North.

Can anyone confirm? I guess a call to Mongoose would clarify.

Finally, thanks to all who have contributed information to this thread! There is a lot of devoted GS fans here, and I love educating myself with everyone's experience and knowledge to further help my GS ownership experience and which changes I want to make to the car.

silverslashstreak

Just give Gary a call AT Moongoose great guy to talk to and very helpful

Jeff

jim lockwood

Gary is definitely a good guy.

Jim

Sam Kalmuk