510 Race Car Build

[Stoffregen Motorsports]

22 hours ago, paradime said:

 

A few anecdotes of my own and zero judgement of flares beyond my personal taste - Even with 378 whp, using a GPS speedo my SR20 swapped 510 topped out at just under 140 mph.

I do recall you telling me that.

 

Does the rack mount in front of or behind the wheel centerline? The reason I ask is, there is an issue with front or rear steer. Rear steer tends to be very touchy and you need to be careful with your steering input at high speeds, which makes it more susceptible to wander. Even a ton of caster doesn't make it go away. Front steer seems to be immune to this problem.

 

Note - this knowledge is based on experience obtained many years ago, and maybe things have changed. Tire technology could make a massive difference.

 

Speaking of tires, here's a funny story - back when we raced ITC 510s, we had a hookup with Toyo tires, and were given many free sets of tires to go test for them. They brought over a whole container of tires from Japan and just wanted input. My brother and his friend, who worked for AIM tires at SPIR, thought it would be fun to mess with everyone by marking the tires with different info, so we'd write things like PROTOTYPE SET 2 , mark them with many slashes to indicate way more heat cycles than they actually had, and other bullshit. Mind games to mess with the minds of our fellow competitors.

[paradime]

3 hours ago, Stoffregen Motorsports said:

I do recall you telling me that.

 

Does the rack mount in front of or behind the wheel centerline? The reason I ask is, there is an issue with front or rear steer. Rear steer tends to be very touchy and you need to be careful with your steering input at high speeds, which makes it more susceptible to wander. Even a ton of caster doesn't make it go away. Front steer seems to be immune to this problem.

 

Keep in mind, it can only be used with a front sump pan to make room for the rack itself. I'm pretty sure the rack kit doesn't change the actual steering pivot position, and replaces the original crossmember, steering box, drag link, idler arm, tie-rods, and steering knuckles adding up to a sizable weight loss. That said, JBC used computer modeling to completely redesign the steering geometry. It has a custom X-member with narrowed and raised pickup points, and shorter steering knuckles with completely different rotation and progression ratio. Also necessary mods for correct Ackerman ratio. Not sure what voodoo magic they used, but we're lowered 2.75" with only +2 degrees caster. All without losing breakaway predictability accelerating out of corners, absolutely no bump issues, or twitchy wheel instability. Seriously fancy stuff going on there. As I said before, compared to the 510's semi-elastic vaguely responsive steering system, this feels like cheating on an old girlfriend. 

[Stoffregen Motorsports]

Good point - it's much easier to account for ackerman on rear steer knuckles.

[Stoffregen Motorsports]

Not Datsun related, but who really cares.

 

Race report. CSRG Laguna Seca

Wow, what a weekend. As per usual, we got a late start and rolled into the pits with 45 minutes before our first session. The car was fully prepped and only needed fuel and tire pressures set to go on track.

The first session out was a recon session since my brother had not driven here since, well, a long time ago. The car wasn't running great on track either, with loading-up problems and a tad bit of popping at higher RPMs.

Second session, we did a plug-cut to find the problem, and found lean plugs, so I richened it up and set the hood back on and told him to get back on track to finish the session. The car wouldn't even start, with black smoke chugging out the tailpipe. I quickly removed the hood and leaned it back out, so it would fire, then sent him back out on track. Weird, huh? Obviously something going on there.

After speaking with the guys at the track, Jim from Huffaker and Joe Carr both urged me to close up the plug gap, which I did, then the car ran much better. I was worried though, because in the rush to get the car running during the last session, I adjusted the well jets so quickly that I didn't know how much I was turning them. Felt like three flats, but who really knows? So I told Nick to watch the AFR gauge next session for mixture.

Qualifying went well, as we grabbed pole position, but the car was bottoming out in turn six, going up the back hill towards the corkscrew. Heck, it was bottoming out there too, so hard that the left rear tail light lens popped out. My son Cary was watching in that turn and saw it come out, but then saw it get run over by another car. Back in the pits, trying to figure out what to do about the bottoming out, we decided that there wasn't anything we could do. The car was working so well that we didn't want to change anything. The heim joint at the front of the right lower control arm was getting worn down by grinding on the pavement, so we removed it and turned it around so it could grind away at the opposite side of the heim.

During the session, Nick had a big off in turn three, and nearly spun the car. Later on in the session, he got so sideways in turn eleven that I was convinced there was oil on the track. The yellow Mini of Don Racine was smoking some, so I figured it was he who was putting down the oil. Nope, what we found was exciting. Apparently, during the off track excursion, the panhard bar bracket broke, making the back end loose. We don't carry a welder, so we borrowed one and got to work cleaning the parts so I could weld it back together. The welder was a flux core MIG, and was putting down some bird shit welds, but I cranked up the heat and built up the metal around the broken joint. I was convinced it would break again.

One thing we've learned is that this car does not like to run at 8/10ths. It loads up when not running the hardest, and as we put more time on the track, it began to smoke out the tailpipe, but only on decel and between gears. My solution - gap three more sets of plugs and change them out after every session. I was not convinced that the oil consumption had anything to do with the lean/rich condition. Which was a conundrum in itself. I think the plug gap adjustment will prove to be the answer there. But we will have to tear down the motor to find the cause of the smoking. Maybe have some thing to do with the fuel pressure regulator. I'll check into that too.

Saturday's race was a runaway win for us. We were competing with B Sedan cars, which have 100 horsepower more than we do, so we knew we were going to get jumped on the start, which we did. Just as the flag dropped, a very nice Alfa tore by Nick on the outside going into turn one. But...the B sedan cars weigh more too, so Nick just drove right around him on the outside of turn two. And stayed out front the rest of the race. Scott Brown started in fifth position and has an in car video of the race, and you can only see my brother Nick in the video for the first couple laps. After that, he was so far ahead of the field that he was just gone. Seven second lead over the pack.

Sunday's race was scheduled to be at 4:30, so as a group, we all decided to use the morning warm up session as the race itself. CSRG approved that decision and we ran the race at 11:30, instead of 4:30. We started on the pole again, but this time, right next to a very quick Lotus 7. His car is so much lighter and has more HP, so we were convinced that he would jump us on the start, and stay there. My solution? I told Nick to start the race at racing speed. It worked and Nick quickly jumped out into the lead. He held the lead until turn eleven, where he overcooked it going into the turn and spun. This is where the tuning issue really got us, because he wasn't initially able to restart the car. He eventually turned the fuel pump off and got the car to fire, but by this point, the whole field had gone by. With ten seconds between him and the second-to-last car in the race. Nick is a good driver, but more than that, he's a safe driver. He knows how to pass. There were a few sketchy moments getting by some of the cars, with one car not even realizing Nick was there. Luckily, Nick noticed this and waited until after the turn to pass, That turned out to be a good call, as the driver came right down to the apex a split second after Nick clamped on the brakes. I think we finished 12th in that race, but not sure. Oh, the shift lever broke during that race, just under the knob, at the threads. Nick chucked the shift knob out of the car at the corkscrew so it wasn't bouncing around dangerously in the car. My son retrieved it from the turn worker after the race!

It was a good weekend. Our learning curve was steep, and we broke a few parts. We have made great friends who continue to help us a bunch. Our car is good, and Nick is an excellent driver. Do we care that we finished so poorly on Sunday? Not really. It's fun just to be there. This is our third race since we started racing again after such a long hiatus from the sport, and we seem to be picking up where we left off. I am getting comfortable enough with the car, to the point that I feel comfortable giving other drivers and mechanics help with their mechanical problems. It's nice to be back in the sport. It's hard to remember why we ever left...

On our drive home, we popped a heater hose in my Dodge. Fixed it in less than 15 minutes on the side of the road near Hollister. That's teamwork!!!

Here's a link to that video I mentioned. Thanks to Scott Brown for sharing it with us.

 

 

[iceman510]

Interesting weekend in many aspects.  Nice report.  Triumphing (sorry, yours is not a Triumph) over adversity is all part of the battle.  Good work.

 

Last month at Road America between my buddy's 240 and my 510 we had a broken alternator mount which resulted in a destroyed alternator (240), a damaged front brake line (240), failing rear half-shaft u joint (240), a broken oil pump drive (510-on the grid thankfully), and a shift linkage bolt (510-not visible as it is under the boot) come out, but with help of parts scrounged from competitors and some spares delivered by family, we had everything fixed and made our last 3 sessions/races.  

 

I have run with the LBC group with my 510, and the fastest guys can really run away from me.   I watch how briefly they brake at turns compared to me.  Straights I can stay with or outpace them, but not through the corners.  Fun stuff.

[Stoffregen Motorsports]

Yeah, our car weighs 1300 lbs. Yours, 2300 lbs.

 

Here's another vid, this time, from the Alfa just behind our black Midget.

 

 

[iceman510]

Watching the second video first and then the first one, seeing Nick's pass back of the Alfa right after the start from outside the Alfa instead of inside the car was cool.  Carry that speed.

Edited October 18, 2023 by iceman510

[Stoffregen Motorsports]

@iceman510 Got the gauges and sent you the paypal. Thanks again.

[sick620]

this thread needs more 510 pics 😉

[Stoffregen Motorsports]

I got nothin. But I'll figure something out...

[Stoffregen Motorsports]

Searching the shop for a tool the other day, I stumbled upon a Datsun thing I thought was long gone. It's a template for a dual carb heat shield that I got from Frank Honsowetz, which I used many times back in the day. It's a cool piece of Datsun racing history, and I'll use it to make the heat shield for our race car.

[paradime]

Monna from the Datsun Gods because this build has great meaning to you, your brother, and the Datsun community who will learn from it. Best wishes from one and all.

[iceman510]

On 11/2/2023 at 12:34 PM, Stoffregen Motorsports said:

Searching the shop for a tool the other day, I stumbled upon a Datsun thing I thought was long gone. It's a template for a dual carb heat shield that I got from Frank Honsowetz, which I used many times back in the day. It's a cool piece of Datsun racing history, and I'll use it to make the heat shield for our race car.

 

Make two when you do it, and I'll buy the second one.  I have one on my race car, but would like one off that template.  I can use one of them on my 69 street 510.  

[Stoffregen Motorsports]

Yes, I can make one for you.

 

The lower half of the shield was doubled up and sandwiched a piece of asbestos fabric. It was riveted together. The fabric used to be available through Mikuni, and last I checked, was not easy to find anymore. There are other materials that one could use, like the peel and stick reflective cloth, but it won't work as well as the asbestos.

[paradime]

3 hours ago, Stoffregen Motorsports said:

 There are other materials that one could use, like the peel and stick reflective cloth, but it won't work as well as the asbestos.

X2 on that advice. Reflective tape is not only far less insulating, it doesn't hold up near that much heat. I used it on the shield I built to protect the brake master cylinder from the exhaust turbine and down pipe on my SR20 510. Within a year it was cooked brittle and peeling off. I riveted in a welding blanket and it worked WAY better, and still is 9 years later. It's not as easy, but doing it right the first time is always worth the effort in the long run. 

Edited November 5, 2023 by paradime

[Stoffregen Motorsports]

I tell you what guys, I am having so much fun being involved with racing again. Even though we weren't racing this last weekend, I did make a trip to Thunderhill to see they guys. It felt weird being there without a race car.

 

I'm also having a blast building my other Sprite race car. It's coming along, with nearly all of the fabrication done, including brackets for things, placement of catch cans, fuel pressure regulator, brake light switch, battery kill switch, etc. I got the dash done and even the exhaust is done up to the rear axle. I am to the point where I can start plumbing and wiring. Having the car in the shop is a real distraction for me. I played hooky all day yesterday to work on the race car.

[Crashtd420]

It's good to be your own boss....

[five1oh]

just curious....will this thread ever become a 510 race car build??  🙃

[Stoffregen Motorsports]

Not for a while. The car is on the back burner. I may have jumped the gun a bit on the thread. I got excited...

 

I'm having so much fun with the Sprites/Midgets that I almost don't want to build the 510.

 

Maybe I should change the name of the thread so I can talk about the Sprites/Midgets too!

[five1oh]

2 hours ago, Stoffregen Motorsports said:

Not for a while. The car is on the back burner. I may have jumped the gun a bit on the thread. I got excited...

 

I'm having so much fun with the Sprites/Midgets that I almost don't want to build the 510.

 

Maybe I should change the name of the thread so I can talk about the Sprites/Midgets too!

It's all good, I just enjoy giving you a hard time.  Carry on....And I personally hope you build this 510

[paradime]

5 hours ago, Stoffregen Motorsports said:

Not for a while. The car is on the back burner. I may have jumped the gun a bit on the thread. I got excited...

I'm having so much fun with the Sprites/Midgets that I almost don't want to build the 510.

Maybe I should change the name of the thread so I can talk about the Sprites/Midgets too!

A shift in attention is understandable, but it took a while to process this reply. It begs the question,  WTH just happened here? With much excitement, support, and interest from many in the community, now 4 pages in, you "almost don't want to build the 510"? Rather than offering motivation, I have to say this pivot feels like a bait and switch. You invited us here for your return to "Datsun" with a 510 vintage race car project for you and your brother. I can't speak for others, but that's why I'm here. Unfortunately, you're no longer dedicated to this title and want to pursue your Midget fun right now. All good on it's own, but while the 510 collects dust on the back burner, your Midget fun is salt in the wound, so just drop it from the title for now. When you're attention shifts back to building this 510, change the thread back and I'll be there. 

[KELMO]

13 hours ago, paradime said:

A shift in attention is understandable, but it took a while to process this reply. It begs the question,  WTH just happened here? With much excitement, support, and interest from many in the community, now 4 pages in, you "almost don't want to build the 510"? Rather than offering motivation, I have to say this pivot feels like a bait and switch. You invited us here for your return to "Datsun" with a 510 vintage race car project for you and your brother. I can't speak for others, but that's why I'm here. Unfortunately, you're no longer dedicated to this title and want to pursue your Midget fun right now. All good on it's own, but while the 510 collects dust on the back burner, your Midget fun is salt in the wound, so just drop it from the title for now. When you're attention shifts back to building this 510, change the thread back and I'll be there. 

Sometimes these things happen with project/build. See my build threads for "So, I bought this goon" and "Maure". The Goon thread is fixing to be 11 years old this coming May. I had much excitement when I brought it home and generated some interest with the thread. The "Manure" thread intermingled with the timeline of the other thread. While the "Manure" car is done (for all intents and purposes), the Goon moves forward ever so slowly. I get the disappointment. However, it seems this thread may have rekindled the "race car guy" in him.

 

My $.02 worth.

[Stoffregen Motorsports]

17 hours ago, paradime said:

A shift in attention is understandable, but it took a while to process this reply. It begs the question,  WTH just happened here? With much excitement, support, and interest from many in the community, now 4 pages in, you "almost don't want to build the 510"? Rather than offering motivation, I have to say this pivot feels like a bait and switch. You invited us here for your return to "Datsun" with a 510 vintage race car project for you and your brother. I can't speak for others, but that's why I'm here. Unfortunately, you're no longer dedicated to this title and want to pursue your Midget fun right now. All good on it's own, but while the 510 collects dust on the back burner, your Midget fun is salt in the wound, so just drop it from the title for now. When you're attention shifts back to building this 510, change the thread back and I'll be there. 

What, are you trying to guilt me into building the Datsun?

 

I've actually already come up with a plan - first thing, it need to go to the blasters, then on the rotisserie. The problem is, the rotisserie takes up so much space in the shop that I need to make room for it first. Making room means getting three paying jobs built first, and that's where the time comes in.

[Stoffregen Motorsports]

3 hours ago, KELMO said:

Sometimes these things happen with project/build. See my build threads for "So, I bought this goon" and "Maure". The Goon thread is fixing to be 11 years old this coming May. I had much excitement when I brought it home and generated some interest with the thread. The "Manure" thread intermingled with the timeline of the other thread. While the "Manure" car is done (for all intents and purposes), the Goon moves forward ever so slowly. I get the disappointment. However, it seems this thread may have rekindled the "race car guy" in him.

 

My $.02 worth.

This does happen. I try my hardest to "get it done" once it's been started, but often this means getting to a stopping point and then stashing it away for a while. I like to work in terms of tools. If I'm doing sheetmetal repair and body fabrication, then this entire set of tools need to be brought out, and a workspace needs to be usable. So I go until I can't do any more sheetmetal fab before I put the tools away. Same goes for wiring, plumbing, mechanical, etc.

 

Even then, my definition of stashed away isn't like putting into a storage unit. It will be around the shop, in my line of sight, and that helps with forward motion.

[paradime]

3 hours ago, Stoffregen Motorsports said:

What, are you trying to guilt me into building the Datsun?

 

 

No, my reaction to the reply you gave for Five1oh's question did bum me out, but my reply had nothing to do with trying guilt you into anything. You know I'm a fan of your work, your attention to detail, and you know I'm a HUGE fan of vintage 510 racing. I'm following this thread with great excitement as I'm sure many other 510 fans are. To some degree, I feel personally invested in the 510, and I don't give a shite about the pace of this build. While I totally support your fun racing the Midget, I hoped you'd understand why I'd rather not see it here. Try reading what I said through this perspective and maybe my reaction will make more sense. Given what you wrote, if sharing my bewildered disappointment in it makes you feel guilty, that's on you. Either way, I wish you the best of luck and god speed in what ever your doing.