Fangdango! V8 drag car

[johnnydmd]

Fired it up last night with the new gears, and wow, that made a huge difference in tire rotational speed! Those things were going really fast in first gear alone. Didn't put it on the ground because once again the clutch locked up. Then the clutch bell gear backed off and jammed the whole thing stalling the engine. (at first, I thought the engine seized!).

Yeah, that's no good. It never occurred to me that spinning it backwards would cause various things to untighten!

Sooo...I figured out the reason the clutch was locking was because the flywheel nut was loose and backing off and jamming the bell. The flywheel was still seated on the collet tight enough. Since that nut doesn't have any rotational resistance, it was just a matter of tightening it down enough (and putting on some loctite).

Now the gear on the bell is another story. The resistance wants to unscrew the gear. Honestly, the design of these things is dumb. The small gear holds the larger gears in place by clamping down on them. No locking key. Now I could just go ahead and do a couple spot welds and freeze the sucker permanently, but I decided instead to throw some loctite on the threads and torque it down to 50 lb-ft, which I don't think this little engine could possibly unscrew.

I just need to start it up again and make sure that the clutch isn't engaging at idle. If it is, I'll need to drill the shoes out some.

Seeing how fast I got the tires going in first gear alone, I'm really feeling good about this thing's top end. I already know the launch is going to be ok, and I can always do a lot with that in terms of how quickly the clutch engages, etc.

 

[WickedFog]

Can you cut a groove behind the gear to install a snap ring?

 

[johnnydmd]

Can you cut a groove behind the gear to install a snap ring?

Nope, not nearly enough room

 

[CertifiedMike]

That was a quick recovery!
Getting the details worked out now... this is exciting!!!
I still say just send it but...

 

[Xraycer]

I still say just send it but...

NOOOOOO!!!!!!!!!!!!

 

[Xraycer]

NOOOOOO!!!!!!!!!!!!

.

 

[johnnydmd]

Did a bunch of testing over the weekend, trying to get my gears and clutch right. I have the exact opposite problem JQ90 has with my clutch setup. In my case because I'm gearing it way up off the engine to give me a lot of top speed, my idle speed is causing the clutch to engage. This wasn't a problem with the 2:1 gears, but the 3.2:1 made such a massive difference. It also doesn't help that my clutch spins in reverse, which makes it much more bitey. I *could* maybe flip the shoes, but I'd have to get a different flywheel nut, and probably one without a retaining groove, otherwise the shoes sit too high and rub the bell.

I dropped the ratio to 2.5:1 and it was better but still engaging too early. I was using 1mm springs, so I've ordered some 1.10 mm springs which I think will work ok. I really want the 3.2:1 gears though, so I might lighten the shoes some if that still grabs.

Meanwhile I spent time tuning both of my V8's. I was feeling that the one I built may not be firing on all cylinders, so I pulled the plugs and confirmed that some of them were definitely not firing. I compared it to the other engine, whose plugs were all clean, and quickly noted the gap was way too large on the one I built. I cleaned up the plugs, gapped them properly, and ran the engine (I also pulled the trans out to make things quieter so I could tune better). I also put the timing closer to what the other engine was, as that one is just running great. Definitely felt smoother. I will say, much like in JQ90's video, you really have to let these things warm up, and if it's cold outside, forget it, it takes too long, if you can even get it warm enough. Once they are warm though, they idle and respond much, much better.

Only a week away from our first team TnT, and I feel this car is cutting it to the wire. My springs come Wednesday, so most likely I'll only be able to get it configured to at least idle without spinning the tires any.

My newer engine (orange one) I think is more broken in than the one I built (red one). It's spitting less oil, and the oil is staying cleaner longer. Mine is still getting dark and carbon filled pretty quick. Some of that could be from the cylinders that weren't firing too. I noticed I was spitting less oil after I gapped the plugs and tweaked the timing. I really wish they would make some proper exhaust adapters, my homemade units are still pretty leaky, and oil often sprays out of the joint when revving it up high. I think I'm gonna shrinkwrap the joints, getting sick of having to clean the car so much. I'm not spraying that much oil, so I think my oil scraper rings are in correctly. Just a matter of breaking it in more and the rings seating better.

Once I got the red engine warmed up all the way, it was running really well, and idling smoother. I'm able to hit 9k rpm, so maybe the timing isn't perfect yet, these things can get to 10k. Or maybe it just needs to loosen up a little more.

 

[WickedFog]

Did a bunch of testing over the weekend, trying to get my gears and clutch right. I have the exact opposite problem JQ90 has with my clutch setup. In my case because I'm gearing it way up off the engine to give me a lot of top speed, my idle speed is causing the clutch to engage. This wasn't a problem with the 2:1 gears, but the 3.2:1 made such a massive difference. It also doesn't help that my clutch spins in reverse, which makes it much more bitey. I *could* maybe flip the shoes, but I'd have to get a different flywheel nut, and probably one without a retaining groove, otherwise the shoes sit too high and rub the bell.

I dropped the ratio to 2.5:1 and it was better but still engaging too early. I was using 1mm springs, so I've ordered some 1.10 mm springs which I think will work ok. I really want the 3.2:1 gears though, so I might lighten the shoes some if that still grabs.

Meanwhile I spent time tuning both of my V8's. I was feeling that the one I built may not be firing on all cylinders, so I pulled the plugs and confirmed that some of them were definitely not firing. I compared it to the other engine, whose plugs were all clean, and quickly noted the gap was way too large on the one I built. I cleaned up the plugs, gapped them properly, and ran the engine (I also pulled the trans out to make things quieter so I could tune better). I also put the timing closer to what the other engine was, as that one is just running great. Definitely felt smoother. I will say, much like in JQ90's video, you really have to let these things warm up, and if it's cold outside, forget it, it takes too long, if you can even get it warm enough. Once they are warm though, they idle and respond much, much better.

Only a week away from our first team TnT, and I feel this car is cutting it to the wire. My springs come Wednesday, so most likely I'll only be able to get it configured to at least idle without spinning the tires any.

My newer engine (orange one) I think is more broken in than the one I built (red one). It's spitting less oil, and the oil is staying cleaner longer. Mine is still getting dark and carbon filled pretty quick. Some of that could be from the cylinders that weren't firing too. I noticed I was spitting less oil after I gapped the plugs and tweaked the timing. I really wish they would make some proper exhaust adapters, my homemade units are still pretty leaky, and oil often sprays out of the joint when revving it up high. I think I'm gonna shrinkwrap the joints, getting sick of having to clean the car so much. I'm not spraying that much oil, so I think my oil scraper rings are in correctly. Just a matter of breaking it in more and the rings seating better.

Once I got the red engine warmed up all the way, it was running really well, and idling smoother. I'm able to hit 9k rpm, so maybe the timing isn't perfect yet, these things can get to 10k. Or maybe it just needs to loosen up a little more.

It's like breaking in a 1:1, only tinyer huh? But waaaay more touchy.

 

[CertifiedMike]

Did a bunch of testing over the weekend, trying to get my gears and clutch right. I have the exact opposite problem JQ90 has with my clutch setup. In my case because I'm gearing it way up off the engine to give me a lot of top speed, my idle speed is causing the clutch to engage. This wasn't a problem with the 2:1 gears, but the 3.2:1 made such a massive difference. It also doesn't help that my clutch spins in reverse, which makes it much more bitey. I *could* maybe flip the shoes, but I'd have to get a different flywheel nut, and probably one without a retaining groove, otherwise the shoes sit too high and rub the bell.

I dropped the ratio to 2.5:1 and it was better but still engaging too early. I was using 1mm springs, so I've ordered some 1.10 mm springs which I think will work ok. I really want the 3.2:1 gears though, so I might lighten the shoes some if that still grabs.

Meanwhile I spent time tuning both of my V8's. I was feeling that the one I built may not be firing on all cylinders, so I pulled the plugs and confirmed that some of them were definitely not firing. I compared it to the other engine, whose plugs were all clean, and quickly noted the gap was way too large on the one I built. I cleaned up the plugs, gapped them properly, and ran the engine (I also pulled the trans out to make things quieter so I could tune better). I also put the timing closer to what the other engine was, as that one is just running great. Definitely felt smoother. I will say, much like in JQ90's video, you really have to let these things warm up, and if it's cold outside, forget it, it takes too long, if you can even get it warm enough. Once they are warm though, they idle and respond much, much better.

Only a week away from our first team TnT, and I feel this car is cutting it to the wire. My springs come Wednesday, so most likely I'll only be able to get it configured to at least idle without spinning the tires any.

My newer engine (orange one) I think is more broken in than the one I built (red one). It's spitting less oil, and the oil is staying cleaner longer. Mine is still getting dark and carbon filled pretty quick. Some of that could be from the cylinders that weren't firing too. I noticed I was spitting less oil after I gapped the plugs and tweaked the timing. I really wish they would make some proper exhaust adapters, my homemade units are still pretty leaky, and oil often sprays out of the joint when revving it up high. I think I'm gonna shrinkwrap the joints, getting sick of having to clean the car so much. I'm not spraying that much oil, so I think my oil scraper rings are in correctly. Just a matter of breaking it in more and the rings seating better.

Once I got the red engine warmed up all the way, it was running really well, and idling smoother. I'm able to hit 9k rpm, so maybe the timing isn't perfect yet, these things can get to 10k. Or maybe it just needs to loosen up a little more.

I would say something like, "You wouldn't believe how excited I am to see this car run!!!"
But then I thought... maybe...
I hope you get the springs in time and get a run in again soon!!!
Too cool that YOU actually built this!!!

 

[johnnydmd]

I would say something like, "You wouldn't believe how excited I am to see this car run!!!"
But then I thought... maybe...
I hope you get the springs in time and get a run in again soon!!!
Too cool that YOU actually built this!!!

Thanks man, it's close, I hope. All of the stuff coming apart with the clutch and the inability to gear it up the way I wanted was a little disheartening, but I'm keeping at it. I've still got a number of tricks up my sleeve to get it right. It's not far, I think with the heavier springs it'll work fine with the 2.5:1 gears. For the 3.2, that I might need to play around with the shoes some more.

Had some issues with the engine too, serpentine belt kept walking off one of the roller pulleys, which I tracked to it not staying seated on its bearings. I really want to eventually do something better with the exhaust too.

 

[CertifiedMike]

Thanks man, it's close, I hope. All of the stuff coming apart with the clutch and the inability to gear it up the way I wanted was a little disheartening, but I'm keeping at it. I've still got a number of tricks up my sleeve to get it right. It's not far, I think with the heavier springs it'll work fine with the 2.5:1 gears. For the 3.2, that I might need to play around with the shoes some more.

Had some issues with the engine too, serpentine belt kept walking off one of the roller pulleys, which I tracked to it not staying seated on its bearings. I really want to eventually do something better with the exhaust too.

I'm doing the same dance right now. One step up, 2 back.
You are close! Hopefully you can get that clutch issue worked out easy! Its always the details...

 

[Doom!]

This hurts my brain!

 

[johnnydmd]

Ok, so at our TnT this weekend, I had Fangdango with me, determined to get some data and testing done. Going in, my biggest thing was figuring out what gears I should be using on the engine output shaft to clutch shaft. The low end 2:1 setup, the mid range 2.5:1, or the top end 3.2:1 where my choices. I had put the heavy springs on, and the 3.2:1 to start off with.

It was only 54 degrees, so I had to spend a decent amount of time warming up the engine. After getting it warmed up and tuned, I drove it around lightly. The car was able to idle without moving forward, but it definitely felt like it was grabbing a little early. After a little light driving, that seemed to abate as the shoes (now facing the traditional direction) wore in properly. I noted that with those gears, the car moved very fast without much throttle at all. I also noted that at about 25mph, even light on the throttle, the car's rear kept trying to come around the front Granted, the track was dusty and low traction, but there was definitely something going on there. We all kept trying to see and came to the conclusion that the car's front end was diving pretty hard at that speed. Front shocks are way too soft, and combined with the car's aero, it's pushing down way too much.

At that point, I just decided to test the launch. Without using the trans brake, it felt a little sluggish with these gears and clutch grabbing so early. So, I engaged the trans brake, bumped the idle up (man it sounded awesome too), and let it rip off the line. That thing exploded off the line with a ton of wheel speed, lifting the front up and smoking tires. I went to try again, and heard some weird noises, then it stalled out.

So, I popped the body off and saw aluminum shavings and dust everywhere. I saw that the flywheel had come loose and moved back, causing the gear to rub the trans supports.

Yikes!

Yeah, that's not supposed to be sitting that far off the crank!

Yup, the collet was slid back, no doubt. Why? My fault. I forgot to loctite the bolts holding the flywheel to the collet. They were loose. Doh.

Aside from the gear getting mangled up pretty good hitting the support, it's also obvious that these aluminum gears will not hold up long. That little bit of use, and you can see them already worn badly. I was seeing quite a bit of aluminum dust in the car even before this mishap. So, steel gears are on the way.

While I had tried to better seal the header adapters, I was still getting a good bit of leakage/spray from the exhaust. While the amount of oil consumed is decidedly less as the engine breaks in all the way, it's still not suitable. I decided to take the engine out and re-do the joint. I ditched the gasket, I think that was the main problem. I grinded down the flanges and got them perfectly flat. I bolted it up, and it seated much, much better.

I also now have shortened the adapters as having a full metal exhaust that pokes out of the body is likely to cause potential damage to the headers in a wreck. Now I use a rubber nitro exhaust extender as an elbow that slips onto the exposed copper tube and use a CF tube to exit the body. I did fix the belt issue, that stayed on the whole time, had to shim out some of the pulleys as they did NOT match up perfectly out of the factory. I do need to pick up another one of those belts as that one got a bit shredded on the edges from when it was popping off before. It still works though.

I put in some longer, heavier springs in the front shocks and will see if that keeps the front up better. Otherwise, I might have to come up with something there, either additional shocks or something even beefier, if possible. While I had it apart, I went ahead and swapped out the old bottom plate with the new design that is stiffer (everyone said they saw the car twisting when it launched). I may still have to do some more cross bracing.

The main takeaway was that I did get the gearing ratio and clutch set. This car though, is still very much in an R&D stage. I think now the focus needs to be on getting the car stable at higher speeds, like 60+ mph. One thing is also noticeably different to me, is that with the nitro cars it's very easy to "feel" and control it. This car is a different beast. That's the difference in having an engine that has 7x the torque.

 

[CertifiedMike]

Ok, so at our TnT this weekend, I had Fangdango with me, determined to get some data and testing done. Going in, my biggest thing was figuring out what gears I should be using on the engine output shaft to clutch shaft. The low end 2:1 setup, the mid range 2.5:1, or the top end 3.2:1 where my choices. I had put the heavy springs on, and the 3.2:1 to start off with.

It was only 54 degrees, so I had to spend a decent amount of time warming up the engine. After getting it warmed up and tuned, I drove it around lightly. The car was able to idle without moving forward, but it definitely felt like it was grabbing a little early. After a little light driving, that seemed to abate as the shoes (now facing the traditional direction) wore in properly. I noted that with those gears, the car moved very fast without much throttle at all. I also noted that at about 25mph, even light on the throttle, the car's rear kept trying to come around the front Granted, the track was dusty and low traction, but there was definitely something going on there. We all kept trying to see and came to the conclusion that the car's front end was diving pretty hard at that speed. Front shocks are way too soft, and combined with the car's aero, it's pushing down way too much.

At that point, I just decided to test the launch. Without using the trans brake, it felt a little sluggish with these gears and clutch grabbing so early. So, I engaged the trans brake, bumped the idle up (man it sounded awesome too), and let it rip off the line. That thing exploded off the line with a ton of wheel speed, lifting the front up and smoking tires. I went to try again, and heard some weird noises, then it stalled out.

So, I popped the body off and saw aluminum shavings and dust everywhere. I saw that the flywheel had come loose and moved back, causing the gear to rub the trans supports.
View attachment 228242

Yikes!

View attachment 228243

Yeah, that's not supposed to be sitting that far off the crank!

View attachment 228244

Yup, the collet was slid back, no doubt. Why? My fault. I forgot to loctite the bolts holding the flywheel to the collet. They were loose. Doh.

View attachment 228245

Aside from the gear getting mangled up pretty good hitting the support, it's also obvious that these aluminum gears will not hold up long. That little bit of use, and you can see them already worn badly. I was seeing quite a bit of aluminum dust in the car even before this mishap. So, steel gears are on the way.

While I had tried to better seal the header adapters, I was still getting a good bit of leakage/spray from the exhaust. While the amount of oil consumed is decidedly less as the engine breaks in all the way, it's still not suitable. I decided to take the engine out and re-do the joint. I ditched the gasket, I think that was the main problem. I grinded down the flanges and got them perfectly flat. I bolted it up, and it seated much, much better.

View attachment 228247

I also now have shortened the adapters as having a full metal exhaust that pokes out of the body is likely to cause potential damage to the headers in a wreck. Now I use a rubber nitro exhaust extender as an elbow that slips onto the exposed copper tube and use a CF tube to exit the body. I did fix the belt issue, that stayed on the whole time, had to shim out some of the pulleys as they did NOT match up perfectly out of the factory. I do need to pick up another one of those belts as that one got a bit shredded on the edges from when it was popping off before. It still works though.

I put in some longer, heavier springs in the front shocks and will see if that keeps the front up better. Otherwise, I might have to come up with something there, either additional shocks or something even beefier, if possible. While I had it apart, I went ahead and swapped out the old bottom plate with the new design that is stiffer (everyone said they saw the car twisting when it launched). I may still have to do some more cross bracing.

View attachment 228256

The main takeaway was that I did get the gearing ratio and clutch set. This car though, is still very much in an R&D stage. I think now the focus needs to be on getting the car stable at higher speeds, like 60+ mph. One thing is also noticeably different to me, is that with the nitro cars it's very easy to "feel" and control it. This car is a different beast. That's the difference in having an engine that has 7x the torque.

I do wish you got some footage, just because I love the car so much!
Does anyone in your group have a slow mo cam?
That would answer SO many questions about twist and dive etc...
That gear got chewed up good! Nice work! Hopefully the steel gears will fix you up.
I'm already looking forward to the next posts!

 

[johnnydmd]

I do wish you got some footage, just because I love the car so much!
Does anyone in your group have a slow mo cam?
That would answer SO many questions about twist and dive etc...
That gear got chewed up good! Nice work! Hopefully the steel gears will fix you up.
I'm already looking forward to the next posts!

I think next weekend we'll have some good testing weather. All this week is going to be cold

That'll give me some time to get all the parts in, and do some setup on the chassis/suspension too.

 

[ahr43]

Spot on, Mike, suggesting a slo-mo cam. Griz used so-mo to tune out launch issues whith his nitro top fuel dragster back '06-'07. Big aid. He even got images of my top fuel electric and helped sort out chassis issues my car was having.

Great build on the Fandango. Once sorted, she'll be a terror on the track. -AC

 

[Doom!]

Too much Powa!!!
(Read with Schwarzeneggers accent)

 

[Xraycer]

Too much Powa (Read with Schwarzeneggers accent)

......says no one, ever!

 

[johnnydmd]

Back together, with the redone exhaust, front springs, steel gear on clutch shaft. Ignore the aluminum gear still left on the flywheel, that's getting swapped next week hopefully.

Car sits up in the front much better. About 7 or 8mm higher and doesn't plow down nearly as much. That should help a lot with weight transfer. Part of my mistake was trying to have the same ride height as the smaller scale cars.

I might add an additional cross brace tonight to the chassis to help some with twist.

 

[CertifiedMike]

The exhaust looks great!!!