Winter.... what a DRAG

[Gula]

The same body as the crawler king I believe. Yeah, can't wait to see the mt2, doing one of those too.

[OSRC]

Race report for the past 2 weeks....

LAST WEEK:
Did some mods to the DR10 and was pretty confident heading to the track. I picked up another set of PL Hoosiers and trimmed out a few rows of foam hoping it would soften up the tire.


Also, added some blue shock mounts (stock plastic were already a little sloppy), threaded rear shock bodies (the clips were driving me nuts) and added some mount extensions to stand the shocks upright. Stepped up to a 4200kv motor and was ready to go.


Unfortunately, my setup was way, way off. The DR was unpredictable off the line - so bad in fact, I thought something was broken. Would consistently veer left on launch, and then, randomly, would just switch gears and veer right. Very odd. Never did solve it during practice. Hung my head in shame and parked it.

My HPI however was a missile. Now sporting a 5700kv motor, it ripped all 4 tires off the line and just rocketed down the track. Had to be on my toes, but I managed to (mostly) keep it straight. My best time was a 1.7xx something pass which was .4 faster than my DR! Super clean run though, I was never able to duplicate it.

THIS WEEK:
Dug around with the DR a bit during the week to see if I could figure out what was wrong. Double-checked the shocks with calipers (equal) checked the chassis tweak (fine) and looked all over for broken parts (none, just my wounded pride.) I did find that the swaybar was favoring 1 side a bit more than the other, so I tuned it until both sides were as equal as I could get it.

Pit pic.... Only pics I got to take. Wrenches were flying hot and heavy today!


First run - same veering....both not nearly as bad as before. Once the sauce kicked in and the tire got a few passes, it was much much better. I noticed that I was getting most of the wear on the inside of the tires... a bit of love with the camber gauge and I managed to get both tires running right in the center of the contact patch.


Playing with the preload a bit, and loosening the slipper slightly I got the car tracking straight and true and was making consistently good passes. I was way behind the faster guys though, 4200kv is just not enough motor and no matter how clean I got down the track, I couldn't break the magical 2.0 second barrier. Frankly, the stand up shocks made no difference to me - in fact, I think it was more consistent with the more progressive set-up. But it's set up now, I'll roll with it.

The HPI was another story. My angel last week was the absolute devil this week. Wouldn't track straight worth a damn. Didn't change a thing and for some reason I couldn't for the life of me get a good pass. Tried some spare slicks I had in my pit box and it was even worse. Eventually I dropped the punch down to level 4 and finally was able to cross the finish line headlight first, though I was in the 1.9 range. Odd.


So, coming home I immediately made some changes. I swapped the 5700kv motor over to the DR. I think it's ready for some more power finally now that I'm getting a better handle on tuning it. Moved the battery further back too - having it in the center of the chassis probably wasn't helping rear traction, and quite honestly I never even thought about it when tuning today. My ESC wires didn't quite reach, so I mounted it off to the side and added a bit of weight to the other side to balance the chassis. Not sure about this setup....I may lengthen the wires and put the ESC in front of the battery.



Since I removed the 5700 from the HPI, I put in a 3000kv system for now since it's all I have laying around.


I found that one of the rear tires was coming unglued which may explain some of the odd behavior, and the rear diff was strangely locking at a certain spot. Huh. After tearing it down and scratching my head for a while I found the shaft in the diff was slightly bent(!!) How that happened, I'll never know. It was smooth as silk last week and can't even think of a way that could have happened. Some of those launches are pretty violent, but still... the diff pin?? In any case, while I had it apart I installed a rear locker so now both front and rear diffs are locked. Not sure if that will help or hurt... we'll find out I guess. There's really no setup guide for drag racing touring cars, so it's a lot of trial and error. I still have the center diff though, not sure if I want to lock it or not.

[OSRC]

In other news, Made some progress on some other go fast rides. The 4WD open class is hot... my HPI runs in it, but it's good to have options.

My old HPI MT2SS electric conversion I did a while back (The "Corvette Kart" build from a few years back) would be perfect for this class.... it's been sitting unloved for a while. Dusted off the chassis and cleaned it up a bit. I need to find some electronics to drop in there... but I did find a perfect, 325mm body for it..



The Super Nitro Rally E-conversion is also coming along well. Using a few old HPI chassis as templates, I made a new chassis to get started. I goofed a little on the longer wheelbase holes, my template shifted slightly I guess and they are off to the side by about a mm. Got too much time invested in the chassis, so I'll live with it for now. I don't mind rough edges so much, but I can't stand things being out of square. Thankfully the 280/300mm WB holes are perfect so it's not a total loss. It's a large plate for now, but once I figure out where everything goes I'll trim it down a bit and lighten it up.


For the center trans I found a complete replacement Axial Exo bulkhead and motor mount. Works out great, I already had a few spare spurs, and it uses standard AX10 stuff of which I have a metric crapload laying around, so it gives me the option of 3 center gear sizes, and a center diff or locked with a diff locker. Works so well, I ordered the only other one I could find on Ebay in the US. Genius, wish I had thought of this earlier. The green color will most definitely be stripped!!!


Mounted up the bulkheads and the center trans. Took a bit of fiddling, I wanted to make sure I had the right length dogbones for all the different wheelbase options. Which I do!


Eventually, I'll have 3 HPI based vehicles for the open class....in roughly 1/10, 1/9, and 1/8. Fun stuff.

[Gula]

Holy moly, haven’t seen those "prebuilts" cool for sure, unfortunately the old threads no longer have pictures.
The hpi bullet line uses similar sized parts. I grabbed a center diff from dollarhobbyz_2 when they were cheaper.
Best of luck on your quest for speed. What body is that? How much do the tires expand, or do you "strap, fish line, etc" them?

[OSRC]

The body is from Deltaplastiks. They have quite a few....unique... 325mm bodies. Not the greatest quality - some of the mold lines are not as clear as they could be, but it's good enough for the price. It was between this one and the GT40, though this one was unlicensed and significantly cheaper.

Not sure what tires you are referring to? My drag tires don't expand much, though they don't stay flat. I'm sure my touring tires are ballooning, probably what caused them to unglue a bit. I'm certainly putting a lot of RPM into them. I don't belt any of my tires.

[OSRC]

Making a little more progress on my super conversion.

Narrowed and milled out the chassis...milled, drilled, and countersunk. Maybe not my finest work, but not terrible.


Tried to do something different with the battery tray this time. Insteal of bolting a huge, heavy tray to the chassis, I bent up some aluminum and made some brackets to hold the battery pack. Works like a charm and seems solid enough, I drilled out a few sets of holes so I can run my 90C packs on drag day, and larger packs on parking lot days.



Whoa...pulled apart the diff assemblies to check and re-grease and found a 1-way in the front! Nice! Won't need it for drag racing though, I just put in an open diff for now front and rear. Tempted to lock them up, but with drag season winding down, decided to build it for parking lot fun (Though it'll get a few passes I'm sure)


Assembling the chassis ... shocks have arrived (50mm) and decided to embrace the green and purple... it kinda grew on me. Dropped in a Castle 3800 becaise A) it matched the color and B) it's all I have.




Need to finish up the chassis details and figure out an upper brace. Bumper mount is en-route and then this project is almost done! Just in time for the end of drag racing...supposed to be 50d here tomorrow, I hear the trails calling!

[OSRC]

Well, drag racing season has come to a close. They are still racing on weekends, but with temps warming up, it's trail time for me. I did get my HPI RS4MT2 conversion completed, and got a shakedown run in on the last day of drag racing...


On 3S, this thing is a beast! It even sounds mean with all the metal gears. I never checked the center diff though, and turns out all my fluid had leaked out over the years so I was diffing out the entire way down the drag strip - all the power was going to the front. Front tires ballooned so hard, they took off some paint from the inner fenders. A quick trip to the local dollar store and I had a huge tub of putty for $2.


Packed the center diff and now it's solid as a rock. Car is set up with some old PL 2.2's and a DeltaPlastiks body. With the diff closed, I suspect this car is going to be quite fast! Won't know until next season though.



Still working on the SNRS4 and I have a drag bug MF01 project for next year... I've got all summer to get them done!

[350TacoZilla]

Hey man not to highjack your thread too much here but.... I'm really thinking of throwing one of these no prep drag cars\trucks together and I have 2 different partial trucks I could start with. Kinda looking for input on what you think would be route to go. Both trucks are apart and are missing parts here and there so money wise I think its pretty close, also both would need new motor\esc to even compete since they are both brushed.

Truck #1
Was a telluride 4x4 with slash arms\shocks. Would need to buy a slash 4x4 chassis (or maybe upgrade to LCG chassis at same time)

Truck #2
Slash 2wd I had with cracked chassis, so again would be buying new chassis either way.

I know the 2wd is the norm for the no prep stuff but keep thinking the 4x4 might be different\cool build and might work ok? Difference in drag parts really would come down mainly to 4 drive tires vs 2 drive and 2 steer.

[Timmahh]

Originally Posted by 350TacoZilla

Hey man not to highjack your thread too much here but.... I'm really thinking of throwing one of these no prep drag cars\trucks together and I have 2 different partial trucks I could start with. Kinda looking for input on what you think would be route to go. Both trucks are apart and are missing parts here and there so money wise I think its pretty close, also both would need new motor\esc to even compete since they are both brushed.

Truck #1
Was a telluride 4x4 with slash arms\shocks. Would need to buy a slash 4x4 chassis (or maybe upgrade to LCG chassis at same time)

Truck #2
Slash 2wd I had with cracked chassis, so again would be buying new chassis either way.

I know the 2wd is the norm for the no prep stuff but keep thinking the 4x4 might be different\cool build and might work ok? Difference in drag parts really would come down mainly to 4 drive tires vs 2 drive and 2 steer.

use the slash 2wd. Its the most common platform No Prep is based on. Your 4wd wont be 'legal' in most No Prep races beyond run what you brung type races as they are based on 2wd Short Course rigs which the slash is. jm2c

[OSRC]

Agreed, the 2WD is the way to go. Lots of guys ran 4WD here, but it's because we had a large open class. 2WD is more fun imo, there's definitely some challenge in getting a 2wd car to launch straight whereas a AWD is point and shoot.