INVADER - Nitro Slash drag car

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johnnydmd

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Well, had the day off, so I got busy on this project. First thing I did was make a template, and then see where it would require holes to be drilled.

20211111_104819.jpg


At first I thought, four holes, but then quickly realized that if I made the plate a little longer, it would tuck under the bulkhead and could be clamped down by that like the Slash transmission is (which is held in by that and two bolts in the front). My plan was to just go ahead and drill the holes in the rear anyway for additional support.

I cut my CF, and drilled the holes. As per usual, when ever I manually drill CF, there was a lot of necessary tweaking of the holes to get the dang thing lined up...

20211111_143213.jpg


It was on...but I decided to forgo those extra holes in the chassis by the bulkhead so I wound up countersinking those, and just having the two front ones that actually go through the chassis, since the rear is held rock solid by the bulkhead.

20211111_155038.jpg


One thing with the Jato trans, is that it has this weird open part underneath where the diff gear is exposed. Covering it with a plate, I noticed that the clearance was extremely tight, and that a couple of the gear teeth would rub when rotating ever so slightly. To eliminate that possibility, I beveled the plate some to allow for clearance.

20211111_155031.jpg


Ugly, but it's inside the trans ;)

Then I drilled my chassis, and of course somehow the holes were a little off, so after some massaging of those, I got it successfully installed, and it was solidly in place. There are two more holes where bolts come up through the chassis, then the engine mount, and anchor in the transmission, and they are very close to some existing holes, so I may have to extend those holes some, or drill two more yet.

I sat the engine where it would go, and realized that I was going to also have to move my servo, so I did that, which required a little more drilling.

20211111_113742.jpg


Also, not shown in this pic, I had to trim off the tab that is touching the flywheel (that was where the original transmission's brace connected). Otherwise, plenty of room for adjustments, and no need to cut out a hole for the flywheel since I can raise the engine enough with the CF plate that the engine mount will attach to, which will have a space cut out for the flywheel if the clearance isn't enough (though the mount kit comes with extra spacers so I should be able to raise the engine high enough to avoid that).

The aforementioned rotostart had to also be turned on it's side since it used to sit nicely in the chassis notch. There is just enough room to get that wand shaft by the tire if you're wondering.

20211110_225135.jpg


Notice now there is a lot of clearance for the header. Previously it was very, very close to the tire and would slightly rub when the suspension was compressed down far enough. I'm also waiting on some more 3m spacers for the upper chassis to mount as you can see the one corner is just floating.

My engine mount is coming Monday I think. For that, I will mount it to a CF plate and put some slotted holes for adjustment in that plate, not the chassis. I will try to use as many of the existing holes in the chassis for that plate too, I think I may have to drill one, maybe two holes in the chassis though. Given the slippery nature of these CF plates, I'll scuff the surfaces of the bottom of the plate and the chassis some to prevent slippage, and probably used flanged/knurled nuts. I may also run some turnbuckles from the upper chassis plate to the rear to stiffen things. It's was pretty bouncy without the engine/trans, a bit stiffer with the trans in, so maybe with the entire assembly together it'll be stiff enough. Previously the old trans had that arm going to the upper plate which made things quite stiff, so I want to recapture that if needed.

So far this hasn't really been as difficult as I had heard a few people saying it would be, only a little minor heartache. Pretty stoked to see how this thing runs with the 2 speed. What is even more intriguing is that, well, there are big block mounts available for this transmission, and yes, a big block fits real nicely :D

20211111_114013.jpg


Dare I put that SH .28 p8 in there? Will certainly have to upgrade to steel trans gears (I am doing that regardless). I will think about that one for a while. First I'll be testing out the OS .21 to see how it does, but big block...mmmm...might be too much of a tire fryer to be useful...then again :D :D
 

johnnydmd

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This is getting very close. Engine mount is finished, and I scored an alloy spur guard/brace. Just a couple of items to finish/cleanup, and need a warmer day to do a little testing. Yesterday woulda been perfect, but ah well. It was 70. Today it's 40, lol.

20211118_201920.jpg


The brace works just about perfect, and I had some other piece (the little red thing at the end) from something I don't even know what, that allowed me to mount it to the chassis plate. There is even already a hole there (though it needs a slight tweak to line up perfectly).

20211118_201845.jpg


I also scored some orange arm hinge mounts to replace the blue ones that didn't match the rest of the chassis. Those I had to grind down a bit because the transmission wasn't fitting with them. Note, steel spur gear too. No slipper either.

20211118_201948.jpg


I will test pretty thoroughly with the OS .21 tm first. I'm really curious as to how much time will come off my ET's. My best time with the previous single speed Slash trans was 2.7s, which isn't all that fast (2 years ago that was considered fast though). Now guys are all 2-2.5s with SC chassis cars, and some are sub 2s. I'd be pretty happy with something in the low 2s range with this mill.

Then I will beef up the transmission, replacing all of the internals with steel gears, and better bearings. Because, you know, the next step is slapping a big block in this thing. The BB mount has the same bolt pattern in the base as the SB mount, so my existing CF mount plate will work just fine.

20211119_070815.jpg


I will start with the KE25 and see how that performs. They aren't really the best, and I can't find specs on it but I don't think it's got a lot of top end. I just want to see how it launches, etc, and if things hold up with that somewhat tame BB mill. Then I will put in the Final Destination engine, the O.S .28 p8 which does have decent top end at 36k, and I'll also change the 54t spur to a 53t.

The SH is a 4+ hp monster, I have one in my Dragonoid, and it's a drivetrain wrecker in that rig, but this is going to be a pretty bulletproof drivetrain before I put that thing in. I am still searching daily for an alloy gear case, but no luck yet. Probably will have to wind up buying some Jato roller to get one, lol. Anyway, with that much power, the power to weight ratio for this car will be insane - comparable, or exceeding that of BoLink/RJ Speed pan drag cars. Those nitro cars run times as low as 1.6s, I've seen the slips. Currently the fastest SC chassis car time recorded is 1.78s, set very recently by Frank Uldrick (I think he works for a chassis builder). I'm not sure what motor combo he was running, might have been 4s or 6s, not sure, could have even been 3s to keep it NPRC legal, but that seems a little unlikely. Either way, I am gunning to break that record. With nitro. The power/weight numbers will be there, but can I get it to the pavement? That's going to be the real test. I had some traction issues with the OS .21 tm when I initially built this thing and had the short gears in with no top end speed, and now with the 2 speed it'll be even shorter and torquier on launch. The car also weighed 6.6 lbs then (with body), but is only a little over 5 now. I might have to re-add some weight, and find the magic combo.

Now just have to wait for the weather to be warm enough to run.
 

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This is getting very close. Engine mount is finished, and I scored an alloy spur guard/brace. Just a couple of items to finish/cleanup, and need a warmer day to do a little testing. Yesterday woulda been perfect, but ah well. It was 70. Today it's 40, lol.

View attachment 136850

The brace works just about perfect, and I had some other piece (the little red thing at the end) from something I don't even know what, that allowed me to mount it to the chassis plate. There is even already a hole there (though it needs a slight tweak to line up perfectly).

View attachment 136851

I also scored some orange arm hinge mounts to replace the blue ones that didn't match the rest of the chassis. Those I had to grind down a bit because the transmission wasn't fitting with them. Note, steel spur gear too. No slipper either.

View attachment 136852

I will test pretty thoroughly with the OS .21 tm first. I'm really curious as to how much time will come off my ET's. My best time with the previous single speed Slash trans was 2.7s, which isn't all that fast (2 years ago that was considered fast though). Now guys are all 2-2.5s with SC chassis cars, and some are sub 2s. I'd be pretty happy with something in the low 2s range with this mill.

Then I will beef up the transmission, replacing all of the internals with steel gears, and better bearings. Because, you know, the next step is slapping a big block in this thing. The BB mount has the same bolt pattern in the base as the SB mount, so my existing CF mount plate will work just fine.

View attachment 136853

I will start with the KE25 and see how that performs. They aren't really the best, and I can't find specs on it but I don't think it's got a lot of top end. I just want to see how it launches, etc, and if things hold up with that somewhat tame BB mill. Then I will put in the Final Destination engine, the O.S .28 p8 which does have decent top end at 36k, and I'll also change the 54t spur to a 53t.

The SH is a 4+ hp monster, I have one in my Dragonoid, and it's a drivetrain wrecker in that rig, but this is going to be a pretty bulletproof drivetrain before I put that thing in. I am still searching daily for an alloy gear case, but no luck yet. Probably will have to wind up buying some Jato roller to get one, lol. Anyway, with that much power, the power to weight ratio for this car will be insane - comparable, or exceeding that of BoLink/RJ Speed pan drag cars. Those nitro cars run times as low as 1.6s, I've seen the slips. Currently the fastest SC chassis car time recorded is 1.78s, set very recently by Frank Uldrick (I think he works for a chassis builder). I'm not sure what motor combo he was running, might have been 4s or 6s, not sure, could have even been 3s to keep it NPRC legal, but that seems a little unlikely. Either way, I am gunning to break that record. With nitro. The power/weight numbers will be there, but can I get it to the pavement? That's going to be the real test. I had some traction issues with the OS .21 tm when I initially built this thing and had the short gears in with no top end speed, and now with the 2 speed it'll be even shorter and torquier on launch. The car also weighed 6.6 lbs then (with body), but is only a little over 5 now. I might have to re-add some weight, and find the magic combo.

Now just have to wait for the weather to be warm enough to run. It was 70 here yesterday. Now it's 40, lol.
That thing is MAD! Nice build dude!
 

johnnydmd

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20211121_204607.jpg


I had forgotten this pic - this shows the engine mount (silver) and how it sits on the CF mount plate. Also shows the flywheel guard/brace and how it mounts to the chassis. I need to find out what the heck I got that red piece from, lol. I have a few of them, I feel like maybe it came from a bellcrank kit, but not sure.

Anyway, the car is good to go, but it's cold here still. Very. Might jump into the 50's on thursday, so maybe I get a shot at testing.

I have a list of "to do" stuff for the car over the winter.

1. Steel transmission gears. ( a must, really ).
2. Big block engine mount.
3. Dual alloy disc brakes, and functional parachute.
4. The new STRC rear arms with 1 degree of toe in vs stock 3 (supposedly this really helps top end speed, and reduces potential tire shaking in the middle).
5. Upgrading radio (though that's not specific to this car, it's for all my drag cars).
6. Lastly, I'll be trying my KE25 and SH28-8, but in the end I'm probably going with a Nova 28-8 with ceramic bearings.

I'm also spending the Winter building a drag car for a friend/team mate. This will be a big block nitro Jato based car, using the new Proline Pinto body. The car is at my house, along with an SH28-3. The build sheet looks as follows:

jatobuildlist.jpg


Hoping he doesn't have sticker shock when he sees it.
 

johnnydmd

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@johnnydmd Much bigger on those gears and your going to need a chain drive! 🤣

That 24t clutch bell is the biggest there is for 1/10 clutches as far as I am aware. This is actually the stock gearing for the Jato, which claims 65+ mph with the TRX 3.3 (I saw it was tested to actually be 71). They also claim it'll reach 60 in 4 seconds, I would guess though that would make a stock Jato around a 3 second 132 foot car with that engine at about 50 mph or thereabouts. Stock Jato is 5.19 lb, which is nearly exactly what I'm at with my car (5.22 lb). So these numbers are pretty encouraging IMO. The OS .21 tm is significantly more powerful than a TRX 3.3, and obviously a big block .28 is vastly more. I'm thinking that 54t gear will get swapped out for something taller, like maybe even as far down as 46t, given the power increases.

[EDIT] - Found a video of a guy running a Jato with a 3.3 that backs up my guestimate - actually a bit faster than I thought -

2.7 seconds at 51 mph. That's pretty encouraging, I should be able to demolish those times with the OS .21 tm.
 
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johnnydmd

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Eeeehhhh....kerbloooom!

260755640_10222043599222497_4378501970495951276_n.jpg


Well, the stock nylon gears (which I'm thinking may have been old and brittle) detonated after just a couple of test launches. I had already planned on ordering steel gear kit, so I wasn't too upset, but I didn't think it'd blow that quickly with an OS .21 tm, lol. Not pictured, but the secondary shaft that the 2 speed gear rides on also broke (at the point that the lock pin goes through). Parts on the way.

I really, really wish I had the aluminum gear case too. The case wasn't damaged, but I still shudder at the thought of it blowing up, and ruining my 100 dollar steel gear set. As with most drag cars, I'm not using a slipper clutch, but I wonder if having the lighter clutch shoes that it simply slammed a little too hard. I do plan on putting the heavier shoes back in, there's not much need for that with having a first gear now. I mean, probably it's just those gears were ancient and brittle...probably....
 

johnnydmd

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Just scored an aluminum gear case! I was hitting up Ebay several times a day waiting for one of those to pop up...
s-l1600.jpg


Hardened steel gears should arrive in the next couple of weeks, I do have a spare set of nylons I could test with I suppose. I also purchased the Hot Racing slipper. It's lighter than the stock one, yet has more pad area, so it should do the job.

Anyway, I'm super stoked about making this drivetrain bulletproof again :D Best of all, I was able to get the silver gear box, so it won't be a mismatched looking one.
 
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