IMSA GTU vintage racer build

[clarkspeed]

And speaking of old photos.  Here is the cold air box I made for the last car.  I 3d printed the ends and air horns.  Then used aluminum angle and sheet to complete.  I got a lot of requests to buy this part.

 

I may do something similar for this car, but not sure yet.  Not positive it will make a power difference on this car.  So I will most likely fab one up after it is running and then test to see if it makes more power.  I am working on the radiator shroud right now and adding a NACA duct for pulling air to a box.  I plan to use 4" hose on this car instead of 3".

 

Edited September 5, 2022 by clarkspeed

[tube80z]

I used to think all 3D-printers were only good for making figurines.  Once your eyes are opened to what they can really do and how much then can help with one-off parts you wonder how you missed this.  Or at least I do.  Love the updates Clarke.

Edited September 5, 2022 by tube80z
clarity

[clarkspeed]

Cheap numeric control changed my life, in the most geeky ways imaginable. I have an engineering background and a natural attraction to building my own parts, so 3d printing opened another world. Basically I noticed the technology getting cheaper and cheaper and after some research, realized I could modify a relatively cheap machine to print final parts in durable, lightweight, and heat resistant materials. It has been a journey, but now just as important as my Sawzall and hammer.  I work with guys who design 3d printed parts for a living (metal), have years experience printing, and have multiple hobby machines at home. But none have  developed the material capabilities that I have. Printing Delrin is took me about a year of trials.

 

The above pictures represent my first step 4-5 years ago.  And if interested in this technology, maybe the only step you need to take. I designed these parts way before I had interest in buying a printer. Just posted them on 3dhub, chose a supplier, and chose material. Local guy who had 20+ machines and was very easy to work with. After I made a couple of orders with him, I would receive new parts in mail before I even paid him.  So to make a long story short, designing in CAD is the first skill you need to master, and the hardest. The parts above cost around $100 maybe. If I printed myself, maybe $30 in material.

 

Now I have my own home built CNC mill I am playing with (separate post) for $500. Building up aluminum and steel capability for decent size parts. And there are DIY designs for CNC laser cutters and plasma cutters also. 

 

And to wrap all this back into original thread, I printed the hood supports just to check dimensions. After verification, I will print the final versions in ASD I think. And I have a design for a multi-port NACA duct that pulls air out of the tiny Gnose opening and directs to the oil cooler and brakes. I will print pics of that once I print the prototype. I have many printed parts in this car I will post as I install. I designed my own cool suit cooler with helmet cooler I am quite proud of. Necessary for racing in Southeast.

 

Judging by the length of this post, can you tell this topic is interesting to me?  I really need to go into production with some of this stuff.

 

 

 

[clarkspeed]

Reviewing posts, I think I missed posting the weight. As you see it in pics, with shell, interior panels, most of suspension, missing calipers and front rotors, rear rotors and external shocks. Came in at 834lbs on scales. Nothing else. Not sure if this is good or bad. I started with 500lbs in first pics of thread with no floor, firewall, or suspension. This is the stuff that keeps me up at night.

 

There is an incredible build thread out there for a pink panther MGB built in Canada for D Mod autox. Amazing to follow and many years of work. He ended up rebuilding 3x to get a decent car out of it. His first shot with similar fab to mine was like 3200lbs or something for final car.

Edited September 6, 2022 by clarkspeed

[JMortensen]

I wish I had the creativity to make 3d parts. My only experience was when Austin Hoke 3d printed a caliper bracket and sent it to me, then I was able to bolt it on and make sure it fit. Was great for that. 

[clarkspeed]

Well, long pause on posts. Spent a week in Germany for work and a week in North Morocco for pleasure. Once again, way behind on progress to where I want to be. So I got the 3d printer back on track on my return. I did some prototypes and then printed a complex duct that routes air from the fiberglass radiator air box (I intend to make next) that directs air from the g-nose inlet to the radiator. The 3d printed part directs high pressure air on passenger side to the brake rotor and oil cooler. I will design another for the drivers side the goes to cold air box and brake rotor. 

[clarkspeed]

Still slow progress. Hurt my back and lost the weekend. Getting really close to having the gnose and fenders fixed. At least I finally have the steering column in. And then found 2 interference points. At least I feel like the week was progress. Slowly chugging along.

[clarkspeed]

Finally, finally, finally, got the front panels locked in with gaps I think are "acceptable". This was pure hell tack welding in the 1/4 turn fasteners where they exactly need to be, then cutting them and rewelding 3 or 4 times, in between fitting the panels 5 or 6 times for each weld. 5 panels fixed, 2 fenders, g-nose, hood, and cowl panel in relation to 2 doors and window frame. Think 3 dimensional chess with 3 players and 3 boards. No way to predict what will happen when you move something 1/8 inch. Maybe 20 hours of this AFTER I thought I already had the fenders in correct place. And this is by no means close enough for a show car. Panel gaps and heights of panels are still all over the place. I'm only shooting for a good aero properties and looking good from 25ft away. But reshaping the FG panels is off limits for this build. I do not have enough time and will not make me any faster. But I still think I may try to alter the hood shape to match the g-nose.

 

I will claim another milestone complete. Next is integrating the customer radiator shroud into the g-nose.

[AydinZ71]

That's exiting man! She's starting to look like a car!

[clarkspeed]

Didn't work very long tonight, but made enough progress to take a picture. CAD design at its best. And fun too!

I decided to integrate the radiator shroud into the G-nose for 1 big FG assembled design. It should not need to be removed very often.

Edited November 12, 2022 by clarkspeed

[clarkspeed]

In addition I finally got my rotors in. It only took 7 MONTHS!  Dropped them on the radial mounts just to take a look. Still missing the ARP wheel studs to finish out the spacers.

 

Does anyone have experience with floating rotors? They really do float. Both axially and radially. I can see why the bolts require lockwire. So how do I check runout with these? Seems like I need to somehow lock down the float first?

[AydinZ71]

Very cool! Well, naturally I have no advice on the floating rotors haha, but that is pretty darn neat! Impressive. 

 

We seem to be on counter-schedules. You seem to make the most progress when im stuck in the gutter ahahha. 

Edited November 12, 2022 by AydinZ71

[tube80z]

22 hours ago, clarkspeed said:

Does anyone have experience with floating rotors? They really do float. Both axially and radially. I can see why the bolts require lockwire. So how do I check runout with these? Seems like I need to somehow lock down the float first?

 

Yes, on my old F2000 and a friends FA car.  What kind of floater are you using?  Is the floater also sprung or is that mounted solidly and only the disk floats?  If you're using bobbins those should allow for a little of each.  There's also the t-nut style and fancier stuff when you go up in dollars.  I've had both bobbins and t-nuts and on each they were torqued to spec and not safety wired.  Did any spec come with the new hardware?  I can give you my advice but since it's 25 to 30 years old I'm not sure you'd want to trust it

 

Prepare to Win claims 0.002 to 0.004 radially and 0.006 to 0.008 axially.  When putting these together I'd check the hub, then with hat mounted, and finally with the disk mounted.  The floater to floater plate will wear over time and you need to make sure none of the floaters get too loose.  That's about all I remember except for having to crack open PTW for actual numbers.

 

Hope that helps,

Cary

[clarkspeed]

It's a t-nut mounted with a Wilwood adapter plate. They came with screws drilled for safety wire so I assume I will lock them. At that specific interface, it's just screw torqued into t-nut. Hardend steel to hardend steel. But maybe a lot of high frequency vibration also.

Your number is exactly the play I have on the rotor. I really just need to verify runout on the hub/hat/plate assembly. I will assume rotor to be true. Just freaked out a little when I bolted it all up and put a runout gauge on it. It rattles with your hand.

[Ironhead]

On 11/11/2022 at 6:47 PM, clarkspeed said:

Does anyone have experience with floating rotors? They really do float. Both axially and radially. I can see why the bolts require lockwire. So how do I check runout with these? Seems like I need to somehow lock down the float first?

 

 

I've used floating rotors for years on a couple of different track cars.  They are particularly important on applications that require a relatively flat mounting hat, because such hats have almost no radial flex and if the discs are not floating they can easily crack with temperature extremes.

 

I've used a couple of different designs, and all of them were secured with bolts and "jet" nuts (all metal lock nuts that "lock" due to elliptically offset threads) and thus required no safety wiring.  In fact, there really wouldn't be any logical way you could safety wire them.

 

The so called "jet" nuts will never loosen anyway, no matter how many heat cycles and how much vibration they are subject to.  Once you tighten one on a bolt, you will understand why.

Edited November 16, 2022 by Ironhead

[clarkspeed]

I could not really find a way to check runout. I will assemble them to the hubs very carefully and hope for the best. I think that .005" play would allow quite a bit of runout without issue. 

 

I was traveling for 8 days but now back on point with the car. Starting from the front I am now working my way back assembling and fabricating to get it ready to get off jackstands and become a roller. My engine is getting close to finish also so I spent a few hours cleaning the oil pan, valve cover, and front cover to deliver next week.

 

Here are a couple pics of the radiator and oil cooler brackets.

[clarkspeed]

New addition to the shop! Almost destroyed my first tire, but didn't scratch the rim!

[tube80z]

Cool additions.  I was looking at some similar models too then a friend bought some and I wonder how often I'll do this versus stop by his shop.  If you don't mind my asking what drove the purchase decision in your case?

[clarkspeed]

On 12/8/2022 at 12:12 PM, tube80z said:

Cool additions.  I was looking at some similar models too then a friend bought some and I wonder how often I'll do this versus stop by his shop.  If you don't mind my asking what drove the purchase decision in your case?

Couple reasons. Main one is not many local shops have experience with race tires/wheels. They tend to be rough on the wheels, bitch about the width and low profile, and use the hammer on weights.  The companies that support racing and show up to track are great. But I have to go to a race to use them. I'm sure there are others locally I don't know about, but that brings up next point....

The cost. Between friends and family I think it will pay back eventually. 

And finally it opens up maybe more cost effective options on purchasing tires on line and used race tires that I can change anytime I want.......I control the process now.

[clarkspeed]

Ran into a problem tonight. My steering shafts are all wanked up. I'm sure I did a fit up many months ago, and vaguely remember the angles were funky, but did not take action then. So I have 2 problems here, large angle at the firewall u-joint, and small angle at rack u-joint. And angle at the firewall is so great the joint is binding when turned.

So do I add an intermediate shaft with 2 more joints or a 3rd U-joint? And if I add 2 more joints do I need a bearing to support?

 

Also spent the day glassing up the front G-nose.