Fangdango! V8 drag car

[johnnydmd]

The exhaust looks great!!!

Well other than that piece of rubber on the end, I might replace that with some shrink tubing, it's there to keep the rattling down.

 

[johnnydmd]

Two steps forward, two steps back.

Great weather this weekend, so I had it all ready, other than my steel gears.

I was wondering how many launches I could make with the worn aluminum gear, and it was exactly 0.

I had other gears, so I put them on. Unfortunately, I think due to it stripping like that it put a lot of lateral pressure on the output shaft, and it was compromised. I started it up and while warming up, the gear fell off, as the shaft broke.

I'm not too sure about these output shafts, though I think I'm the first person to actually break one. Guys with heavier cars have been ok, so I think it was just the gear stripping and putting pressure on it in an unnatural way. I've ordered a couple more, but they could take a couple weeks to arrive. I think I'll take one to a machine shop and see if I can't get one made from hardened steel. I've also asked Cison to make a steel version as well.

My steel gear did arrive in the evening, but that thing weighs a metric ton. I decided to look at some other options. There were a lot of much lighter ones, but they all have 8mm shaft holes, rather than 6mm. I decided to go ahead and order them, and I can sleeve them like I did with ones on the transmission. (Essentially a sleeve with a hole drilled for the set screw to go through to the D-shaft).

I got 40t and 45t versions. I'll use these with the 16t steel gear on the clutch shaft.

So, with that all broken, I spent the afternoon with the engine. Interesting now without all the gear noise, I could hear that the valves/lifters and everything sounded very quiet and smooth. I played around with the tuning and burned about 4 tanks of gas over an hour of playing around.

The new exhaust worked great. No oil spitting from the joints. I did see some oil near the rear of the engine, but that might have been when the gears where stripped and jammed and probably caused the seal to leak some. I cleaned it up and ran, and only saw very small amounts after that, both front and rear - these seals probably aren't the best in the world, but they'll do. I got the engine tuned about as well as possible, I think. It was idling down around 1800-2000, and I found the sweet spot fuel mixture that got it to hit 10k rpm. It spooled up very quickly and was responsive.

One issue I've been having is the radio, ever since I switched from the "classic" 4 channel to the "advanced" 8 channel receiver. The issue was if I got the radio too close to the car, it would totally glitch out and I'd have to shut it off and "reboot" the car. Some days it wasn't as bad (and I think it gets worse as the receiver battery gets lower), but it's mostly a huge PITA. My reason for using the 8 channel was to be able to use the nitrous. I decided to pull it out, and go back to the 4 channel for now. Honestly, I think I was biting off more than I could chew anyway, at least at this point. First things first, make a single pass! I tested some more with the 4 channel, and all was ok again.

After that, I pulled the engine out and cleaned it up. I had a bunch of new serpentine belts and wanted to swap mine out as it had gotten chewed up some when stuff was misaligned. I also wanted to clean up the distributor and hall sensor, because back when I had coolant and oil leaks, that thing got pretty covered in crud. I had noticed once in a while that there was some misfiring going on too, and suspected that to be the culprit, as I wasn't seeing the indicator lights on the sensor. I pulled the distributor (and being very careful to make sure the engine was in the right position internally to retain the timing) and noticed that the hall sensor connector was crumbling apart. I have a pack of 5 spares, so I swapped it out, and put on the new belt too.

The engine was pretty clean this time, thanks to the better sealed exhaust. Now I just wait on my output shafts. I couldn't find anything generic that looked like it would work.

 

[CertifiedMike]

I HATE when I get the shaft!!!
That gear.. WOW!
I guess if you're gonna take the time to break something, break it good!
For all the carnage, it looks like you pulled out of it ok!
The motor sure looks sweet all cleaned and shiny!!!

 

[Doom!]

Two steps forward, two steps back.

Great weather this weekend, so I had it all ready, other than my steel gears.

I was wondering how many launches I could make with the worn aluminum gear, and it was exactly 0.

View attachment 229808

I had other gears, so I put them on. Unfortunately, I think due to it stripping like that it put a lot of lateral pressure on the output shaft, and it was compromised. I started it up and while warming up, the gear fell off, as the shaft broke.
View attachment 229809

View attachment 229810

I'm not too sure about these output shafts, though I think I'm the first person to actually break one. Guys with heavier cars have been ok, so I think it was just the gear stripping and putting pressure on it in an unnatural way. I've ordered a couple more, but they could take a couple weeks to arrive. I think I'll take one to a machine shop and see if I can't get one made from hardened steel. I've also asked Cison to make a steel version as well.

My steel gear did arrive in the evening, but that thing weighs a metric ton. I decided to look at some other options. There were a lot of much lighter ones, but they all have 8mm shaft holes, rather than 6mm. I decided to go ahead and order them, and I can sleeve them like I did with ones on the transmission. (Essentially a sleeve with a hole drilled for the set screw to go through to the D-shaft).
View attachment 229811
I got 40t and 45t versions. I'll use these with the 16t steel gear on the clutch shaft.

So, with that all broken, I spent the afternoon with the engine. Interesting now without all the gear noise, I could hear that the valves/lifters and everything sounded very quiet and smooth. I played around with the tuning and burned about 4 tanks of gas over an hour of playing around.

The new exhaust worked great. No oil spitting from the joints. I did see some oil near the rear of the engine, but that might have been when the gears where stripped and jammed and probably caused the seal to leak some. I cleaned it up and ran, and only saw very small amounts after that, both front and rear - these seals probably aren't the best in the world, but they'll do. I got the engine tuned about as well as possible, I think. It was idling down around 1800-2000, and I found the sweet spot fuel mixture that got it to hit 10k rpm. It spooled up very quickly and was responsive.

One issue I've been having is the radio, ever since I switched from the "classic" 4 channel to the "advanced" 8 channel receiver. The issue was if I got the radio too close to the car, it would totally glitch out and I'd have to shut it off and "reboot" the car. Some days it wasn't as bad (and I think it gets worse as the receiver battery gets lower), but it's mostly a huge PITA. My reason for using the 8 channel was to be able to use the nitrous. I decided to pull it out, and go back to the 4 channel for now. Honestly, I think I was biting off more than I could chew anyway, at least at this point. First things first, make a single pass! I tested some more with the 4 channel, and all was ok again.

After that, I pulled the engine out and cleaned it up. I had a bunch of new serpentine belts and wanted to swap mine out as it had gotten chewed up some when stuff was misaligned. I also wanted to clean up the distributor and hall sensor, because back when I had coolant and oil leaks, that thing got pretty covered in crud. I had noticed once in a while that there was some misfiring going on too, and suspected that to be the culprit, as I wasn't seeing the indicator lights on the sensor. I pulled the distributor (and being very careful to make sure the engine was in the right position internally to retain the timing) and noticed that the hall sensor connector was crumbling apart. I have a pack of 5 spares, so I swapped it out, and put on the new belt too.
View attachment 229812

The engine was pretty clean this time, thanks to the better sealed exhaust. Now I just wait on my output shafts. I couldn't find anything generic that looked like it would work.

Well POOP! It's all going to come together at the same time sooner or later.

 

[CertifiedMike]

Well POOP! It's all going to come together at the same time sooner or later.

And then apart, and then together, and...
Racing is FUN!!!

 

[johnnydmd]

I created this and am having it printed in stainless steel. Supposedly good tensile strength, and gotta be better than the super flimsy aluminum one.

 

[johnnydmd]

Got the 40t steel gear and sleeved it to fit the 6mm shafts. (there is a hole drilled through the sleeve for the set screw). You may ask why, but that is an easy answer - due to the bolt configuration of the output shaft, it was not possible to make the shaft 8mm. The 45t gear arrives today, and I'll get that one ready. Output shaft probably won't arrive until Monday or Tuesday unfortunately, so no testing at our TnT this weekend.

This gear is thinner, and slightly lighter than the bulky 40t aluminum gear, so win-win there. Here it's paired with my 16t gear for a 2.5:1 ratio. I'll probably start with this combo first.

 

[johnnydmd]

So, at long last, the drivetrain is 100% sorted out My steel printed shafts arrived, and I bolted it up. Put on the 45/16 gears for a 2.8:1 ratio.

Fired it up and ran it till the engine was warm. The gears spun freely and evenly. Noisy! That's ok. At idle, the rear wheels were stationary. Few revs and I could see a lot of wheel speed. I do think I found the magic ratio.

The car in it's current state:

I had been contemplating going to a locked diff. It was really nice outside, and I figured I'd go ahead and test things. Warmed it up, didn't even need to touch the needles. Didn't bring a burnout rug, figured I'd just be doing some light launch testing.

The clutch seemed perfect. I had plenty of room to spool up. So, I lined it up, locked the transbrake, and bumped the idle up. Sounded pretty cool! So, I let her rip, maybe a half throttle hit. Well, I can tell you that thing is just a tad bit ROWDY. It was all over the place on the launch, and I had to back out pretty quick (or take out my camera, lol). Here's a long-awaited video of the launch test:

That poor thing was walking on the tire edges almost instantly (you can see it leaves a few black marks), while spinning the tires with ease. Off camera I sent it down the lot at a pretty good clip (30-40 mph or so) and it stayed in first gear, so I need to adjust that for sure. I also wound up giving it a little too much gas and it again got out of shape and did a barrel roll (only minor scratches on the body which buffed out). It landed on its feet, so I brought it back gently, but fast, and yeah, the speed is no issue, it's got an absolute ton of top-end. Brakes worked great too.

Finally, I think I have the chassis/drivetrain completed! Everything worked as it was supposed to. Everything held up perfectly. No more aluminum dust everywhere, and no more oil leaks. The engine seems rock solid. Belt was perfect, coolant is actually staying cleaner now, and while it still spits a little oil out of the exhaust, it's not visible, and there's no smoke. (It turns out many of the users of this engine are realizing that 28cc of oil was too much, needs to be around 23cc).

So, what now? TRACTION!! I NEED MORE TRACTION! First things first - I went ahead and locked the diff. There's no way a limited slip is gonna work for this car - too heavy with far too much torque. So, now it's locked and gonna stay that way. Next, I'm really hoping, somebody will make some properly sized slicks. These tires are the right scale, and they did hook better than the Proline Primes which were like running on ice, but I still feel like a good set of soft slicks would really help here.

The other thing is, I have to learn the car, and how to drive it. I'll get second gear dialed in and start to just make some A-B passes for now. Weather is good, so I have some time.

 

[ahr43]

Thanks for the launch vid and update, johnny. Good hearing locked diff is making for a more predictable launch. Do you think the burn-out rug and RR tire heating will help the launch even more?

Back in the day running full-prep, we would round or radius the outer edge of the tire to help keep the car from hooking when it got over on a tire edge. But that was using foam tires. Not sure it is applicable to rubber. You tried that?

Looking forward to its first race event. Gonna be a thriller for sure. -AC

 

[johnnydmd]

Do you think the burn-out rug and RR tire heating will help the launch even more?

Most definitely. It was only 58 degrees out too. We are supposed to eventually get some better weather that is more in-line with normal Spring.

ut that was using foam tires. Not sure it is applicable to rubber. You tried that?

These tires are really round as it is. I don't think shaving off edges would work on this scale of rubber tire without compromising integrity. I actually do like these tires a lot; they are a super soft compound. Would be better if they were slicks though.

 

[Xraycer]

That thing sounds so cool!

 

[ahr43]

What was track temp? Or does that matter? Sunny day so it may have been a bit higher than ambient 58deg. Track temp was something I used to track and adjust throttle power accordingly. These days on my 33ft and 66ft no-prep tracks, dial in some (-) throttle expo to soften the launch and bring the power in later down track. -AC

 

[johnnydmd]

What was track temp? Or does that matter? Sunny day so it may have been a bit higher than ambient 58deg. Track temp was something I used to track and adjust throttle power accordingly. These days on my 33ft and 66ft no-prep tracks, dial in some (-) throttle expo to soften the launch and bring the power in later down track. -AC

That's a great point. I should be measuring it, and I did not. Next time for sure

 

[CertifiedMike]

OOOOOHHHHHHHHHH!!!! LUCKY CAMERA!!!!
That was awesome!!! Thanks for posting that little rip!!! The car looks and sounds great!!!
Congrats working out your gears and that mess!
I can't wait to see more runs now!!!

 

[johnnydmd]

So, after watching the launch a number of times, plus just how the thing drives, it was becoming very obvious that the front suspension was still far too soft. The car really rolls and lurches badly with any type of steering. I had contemplated previously adding extra shocks, so yesterday, now that I was able to refocus back on this car, I got down to figuring some way to add them. I managed to do it, but the first attempt, which was lined up just about perfectly, didn't work as the clearance on the passenger side wasn't there (distributor in the way). So, I had to put the new shock on the other side of the tower with the other shock, which gave it more of an angle, but testing was good - no binding.

Here you can see that on this side, this positioning was a must due to the clearance. This front suspension has become utterly complex by now.

This made the front end much stiffer. Pressing it down, it returns fully to the top position. I also added a cross brace to prevent flexing of the tower. Because the car now had so much more stiffness, I had to move the shocks to the top position to get the stance back to where it should be.

That stance is perfect, IMO.

Now I have to do something with the rear, as it's very soft too. It's a little different since the weight is in the axle itself, but I do think I need to add shocks, and I want them to be easily adjustable. I do have a bunch of shocks laying around, but I might see if I can get something really nice for it.

 

[luke66]

Gonna go now!!!

 

[Doom!]

Ba da bomp bomp bomp, Another problem bites the dust.

 

[CertifiedMike]

That front end is... SHOCKING!!!
Nice job tucking that stuff in there after the build!
It will prob be easier to get consistent launches with a stiffer suspension.
This is fun to follow. Watching you dial this car has been like watching a 1:1 car come together!

 

[Xraycer]

That front end is... SHOCKING!!!

More @Chubaka jokes like that and you'll be served with suspension, mister!

 

[johnnydmd]

Just looking at a pic at work, I think I can add a short, adjustable shock (which I have a bunch of at home) in this spot. Will have to flip the red shock around, but there's no issue with that, I think.

I could also mount the upper end where the cross brace is just in front of that as well if that gives it better travel. In fact, that looks like a better spot just looking at this.