Street S Maxx build

[Snook Man]

The majority of the parts I ordered have shown up; still need a few more before I can start assembling though.

Although I haven’t used them yet but to bench test and have a look inside, the Savox servos I ordered seem to be good quality and are not as noisy as some of the feedback I’ve seen would let on.

Anyone ever dye the trx cvd dust boots black? If so how well did they take the color and did they come out a true black or purpleish?

[Wildman4910]

That's a nice pile of parts there!

What body is that?

[Snook Man]

Proline E Revo slipstream...

[humayrayakongkinaon]

to bad no one make a body that can cover up the lenght of the arms.
as always snook....awesome build

as for dying the boots, give it a good soak and leave it for 10 mins or less.

[Wildman4910]

to bad no one make a body that can cover up the lenght of the arms.

I have seen a couple using ShortCourse bodies, I really do like the look.

[humayrayakongkinaon]

I have seen a couple using ShortCourse bodies, I really do like the look.

are all 4 tires actually inside the body and not hitting/sticking out the wheel wells? i have a 1/10 rally that i'm setting up for onroad speedrunner and i got the extended arm to widened the stand and my XO-1 driveshaft only have a hair contact on the telescopic shaft, so i order a longer cvd that i'm hoping it would be the right fit.

[Wildman4910]

The wheels don't fit under the body but the arms are covered.

This is what I'm thinking I am going to use for my trucks once I get them built.

http://traxxas.com/forums/showthread...=1#post5076917

[Snook Man]

OK. The boots do dye black well but it takes more than just a 10 min soak…
I hade to simmer the boots in liquid rit dye (1 bottle of dye, to 1 bottle of water) for 15 minutes and then let soak for another hour before the boots turned completely black.

[Wildman4910]

Looks good, I like the boots black a whole lot better then blue.

I may try this on mine, thank you for sharing!

[Snook Man]

Final mockup is complete…

I had to make more changes due to the slipstream body I’m using. The wing mount I had before would have needed a lot of the rear of the body to be cut away in order to clear the mount. The slip stream body for the E-Revo is designed to go with the Revo wing mount so I reconfigured the rear shock tower and added the Revo mount.
I also made a brace for the large air filter that secures it to the transmission housing.

The contour of the slipstream body hugs the air filter and filter neck almost perfectly. I have the body as low as it can go with only 1 round hole for the engine head, if I want to go any lower I will have to cut away part of the rear window area so that the filter neck will clear.

All that’s left is to tear it down, dye a few more small parts and give it a final polish before assembling with locktite.
Haven’t decided on body paint yet but I’m leaning toward Red, with a few chrome paint accents and lots of stickers. I think I’m also going to get more XO-1 rear tires for the front as the fronts look a little too skinny.
Fully dressed with everything except fuel, 8lbs 2oz. as it sits.

[sefh]

Looking good. When should be expect a video of this thing running?

[Snook Man]

Probably not until early spring, unless the weather cooperates and I get a few days off to focus on it.

[danielhr77]

Awesome! Now I see the difference between the front and rear XO-1 wheels before I bought them!

[Snook Man]

Finished…
Body painted also. I took the easy way out and just sprayed it 1 color (Race Red) and added a few stickers.
I took it to the concrete oval track today to get some more run time on the engine and to see what the handling felt like.
4 tanks of fuel, no hiccups and it handles very well. I don’t think it can be flipped over unless I hit something or just loose control at high speed.
I have it locked in 1st gear atm but even so it’s very quick. 70 + mph is looking very feasible.

[rcdriver5]

That is SWEET Snook! The body looks perfect on there with those wheels, and it drives fast, that's just an awesome project you put together there.

[Wildman4910]

That Bad Boy looks fast even sitting still! How about you tease us with a vid?

[Ckeithnitro]

That is a awesome machine!! Can't wait to see it in action..

[Snook Man]

Thanks for the compliments guys.
If the temp warms up today I may unlock 2nd gear and strap a gps to it to see what speeds I’m looking at so far.
Yesterday was just a few runs to see if any bugs popped up and to get a little nitro fix.
I may get a little video later today if the weather cooperates.

[i killed kenny]

nice truck, kind of odd with the small tires sticking really far out of a skinny body

[Snook Man]

I ran 1 quick tank today with the tranny locked in 2nd gear to get an idea of how well the gearing is going to be.
It never got above 54 degrees F today and was windy so I just ran it in the street in front of my house.
I warmed it up to about 185 with a hairdryer and ran almost a full tank before I turned on the camera. I ran out of fuel right at the end of the run on the way back to me as you can hear in the video and I didn’t want to push it any farther with the conditions outside. The little 75cc tank I have recessed into the chassis gives very little warning (no lean tank issue) as to when it’s getting low on fuel. I noticed yesterday that the engine will bark at you a couple times and it’s empty a few seconds later.
It is pulling 2nd gear very well from the start (I was easing into the throttle) and spools up to top rpm’s pretty quickly so I think I have the power still available for taller gearing.
When installed my 3rd gear is a significant jump in the internal ratio and it usually yields 20 to 22mph more than a stock 2 speed does.
I’m going to put it away for now until the weather turns better and I have more time to dedicate to it or I will probably end up crashing it if I hurry.
50.5 mph isn’t too bad with a stock 2 speed and the gears/tires I’m running; I had calculated 48 mph in second gear. I’m fairly confident 70 will fall and now I’m thinking even a little more is possible.
Time will tell.
Oh yea, the run was only 175 feet long when I let off the throttle which is better than I expected.

[Pitola23]

That thing is nice. I saw it in person yesterday and I tell you guys its really nice. Snook man didn't take no short cuts. Good work.

[Wildman4910]

Wow does that engine & pipe combo sound mean!

[i killed kenny]

shinyyyyy lol.

[Snook Man]

I finally got the time and some decent weather to do some more speed run testing.
Lots of problems with the 3 speed…

1st set of problems was with the input shaft/gears. I broke 1 input shaft, broke 2 roll pins for the stock input gears, cracked 2 stock input gears and shredded a plastic 3rd gear input.

Using 1st gear with the torque of the engine at a good rpm was causing a lot of stress on the input shaft and gears at the shift change to 2nd and 3rd.

I now have 2nd gear adjusted to shift asap so I am now basically taking off in 2nd gear with 1st gear just used to get the primary shaft to spin and engage 2nd gear almost immediately.
I also replaced the input 3rd gear with a steel gear to mesh with the primary steel 3rd gear.
Hopefully taking off in 2nd will reduce the load/shock on the stock 2nd gear input and it will last, or I will have to replace both 1st and 2nd gear inputs with steel also.
The input shaft broke where I had drilled it for the added 3rd gear right when the shift change occurred. The new steel gear (28T Tekno pinion) is anchored with a grub screw so I only made a small concave dimple on the shaft to match the grub screw profile so it should be stronger in that area.


After those modifications were done, I broke the FOC output shaft where it was drilled to relocate the plastic FOC gear… Replaced the shaft and that worked ok for 1 shift into 3rd and about ½ way through the power band I shredded the plastic FOC gear…RPM’s through the roof
I have now modified a steel 26T Tekno pinion with a 5mm bore to 6mm to fit the FOC shaft. I did the shaft the same as the input and just made a small concave dimple on the shaft for the grub screw instead of it being drilled completely through.


All of my 3rd gear drive gears will now be steel. Input, primary 3rd gear, primary forward gear and the forward output.


If I have any more failures of the plastic gears I will swap them all to steel also.

Everything that broke imo was a combination of the torque that the engine and pipe are making, the extra speed the gears/shafts are turning due to the sg/cb ratio (28sg/18bell) and no slipper clutch. I knew there would be issues to work out but it seems they all popped up at once.
Other than that the truck ran great with no other hiccups. Handles very well with the length of the chassis and low COG and I don’t need nearly as much room as I though I would to stop. I did manage a nice top speed on the gps on the run when stock FOC gear shredded and the engine hadn’t even got on the pipe yet. If I can get the gears to hold out, it should be interesting…

[Wildman4910]

Sounds like it's gonna be a rocket!

[i killed kenny]

i'll take two! haha, just kiddin' buddy, great looking rig.

[Oldrcguy]

I love to see fine engineering in progress, thanks.

[Snook Man]

Today was a good day for testing. It didn’t end so well though.
After making mods again to the transmission and setting the 1st to 2nd shift point very early everything was going well until I unlocked 3rd gear.
I did 2 easy runs just to see if the shift point from 2nd to 3rd was within a reasonable rpm and then gave it its 1st real WOT run with 3rd gear.
It hit 3rd at what seemed to be just a little early on the rpm’s and was pulling strong and then POP, RPM’s through the roof again.
It turned out to be a broken primary shaft this time. I had modified a foc shaft as a replacement for the stock primary which also can not take the torque either and it broke exactly where I thought it would if it were to break, dead center of the hole to attach the foc gear.
I’m done with breaking shafts and will have some custom made and hardened before giving it another try.
The twin build also uses the same transmission design and no way will it be able to handle the torque with both engines and being considerably heavier than the smaxx.
I’ll get it to hold together sooner or later or both builds are just expensive shelf queens.
On a good note the gears held up well and once I get the shafts made it should be looking good, at least that’s what I keep telling my self




If I can ever keep the transmission together it does have great potential for some high top speed.

The 70mph mark I was trying to reach with the smaxx was surpassed with the broken shaft run and now I’m looking for all I can get.

[Wolfslash16]

The 70mph mark I was trying to reach with the smaxx was surpassed with the broken shaft run and now I’m looking for all I can get.

So you passed 70mph with your S-Maxx? If so, nicely done!

[Snook Man]

Thanks.
Yep, 70+ was kicked to the curb. Now I'm hopeful for something starting with an 8...

Just got to keep it in 1 piece, it would be a disappointment if I can’t beat on it a little bit and something breaks every time out.

[Ckeithnitro]

Nice , your machines are crazy cool..
Do you shoot any video Snook? Like to see...

[Snook Man]

No video of the last test. I was charging the camera battery with plans of filming it later in the afternoon after the lot I usually use for the testing cleared of the cars for the day.
My daughter was even going to go and film for me so I wouldn’t have to mount the camera on a tripod.
The broken shaft happened testing it on my street which is a little downhill so the mph I got wasn’t a true level run and doesn’t really count in my book.
I even had my pit box all packed up and ready to go… C'est la vie

[Zerolimitzrc]

nice build...how come they dont sell the smaxx anymore?

[Wolfslash16]

how come they dont sell the smaxx anymore?

My guess is because a S-Maxx is just a 2wd version of the T-Maxx. Just buy a T-Maxx and remove the front diff, front drive shafts, and the front center drive shaft and ta da! You've got a S-Maxx.

[Zerolimitzrc]

: ) ........ gotcha

[Snook Man]

Update:
I was puzzled at why the primary shaft broke where it did. Not due to there being a hole through the shaft but why it broke where it did when in 3rd gear.
When in 3rd gear, the 3rd gear clutch is in front of the break and everything behind it (1st and 2nd gear assembly) should be free spooling around the owb with little to no resistance meaning the area of the break should have little force being applied to it when in 3rd gear. I did some scrutinizing of the primary shaft and noticed some wear on the shaft where the owb rides and then looked close at the owb. It was toasted and I could see that it had got hot (the bearing was almost new).
This caused me to do a little experimenting and I mocked up another foc shaft as a primary and just installed 1/2/3 input and primary gears to test with compressed air.
After spinning a 36T spur with approx 100/80 psi for 2 minutes in 3rd gear the rpms began to slow dramatically and then suddenly stopped.
I could barely spin the spur by hand and it felt really rough. I sat the tranny down to answer a phone call and approx 5 minutes later picked it up again and once I spun the spur a few times it freed up and spun like it should. I came to the conclusion that the owb and/or the primary shaft is heating up due to the excessive rpms it has to spin with 3rd gear installed and its grabbing hold of the primary shaft and cant work as it should with such tight tolerances. I compared a stock primary shaft diameter where the owb rides against the foc shaft and they are exactly the same. I then put the foc shaft in the drill press and reduced the diameter in just the area of the owb by approx 0.13mm and tested again. After continually spinning the spur for 4 minutes everything spun smooth and free.
I’m still not for sure if the bearing heating up played a big part in the shaft breaking where it did but I do know that it would most definitely rob me of some speed if it were to heat up and cause excess friction.
I will give making another primary shaft 1 more try. I purchased a #2 Vanadium screwdriver and am going to cut the shaft off and use it as a primary shaft. It is 6mm diameter and I don’t want to cut it down to 5mm for the bearings and forward output gear.
I ordered 6x11x4 bearing to use with the primary instead of the stock 5x11x4 so the shaft will have to be reduced in diameter slightly o fit the bearings and will have to modify the steel forward primary gear the same way I did the steel FOC gear to fit the 6mm shaft. That way there will be no through holes and the shaft will be approx 5.97mm through and through except for the area where the owb rides and 2 small flat spots to anchor the 2nd & 3rd gear clutches. If the primary shaft fails again after that I’ll really be scratching my head.

[Snook Man]

After have so many issues with the 3 speed (breaking shafts and smoking owb’s) I decided to switch gears so to speak and revert back to a 2 speed.
I think the main issue with the 3 speed is the stock owb just can’t handle the back spin rpms that’s required once in 3rd gear.
The only way for me to reduce the rpms of the primary shaft and still get the overall ratio needed for the speed was to either decrease the ratio of the rear diff or decrease the ratio of the primary forward and output gears.

I did a couple of test runs this weekend with 30/24 primary/output gearing and got some decent results. I was going easy on it due to I have worn out all my owb I have on hand and didn’t want to smoke another one but I managed to consistently make runs in the mid 60mph range with it without applying WOT until the last ¼ of the run.

This morning I replaced the stock forward primary gear with a 32T gear instead of the stock 28T and replaced the stock output gear with a 22T in place of the stock 26T. That changes the primary/output shaft ratio from the stock .928:1 to .687:1 which considerably lowers the rpm of the primary shaft needed to attain the same relative speed as would my 3rd gear ratio in the 3 speed.

Using a 18T Bell and a 26T Spur I ran a couple of test earlier and got the speed back up over 70 mph on the 1st good pass… 2nd pass not so good, I used an old tranny housing that I had put brass inserts in for mounting to the chassis and the brass inserts pulled out just enough to kill the sg/cb mesh. I went back home and remounted the tranny using longer screws and 3mm nylocks on 3 corners and gave it another go.
2nd good pass after warming up was + 74mph and I was going to go for broke on a 3rd pass but when I refueled I felt a slight bind when I rolled the rig backwards.

After looking it over I found a tooth missing from the 26T pinion gear I’m using as a spur.



Only about 15 high speed passes on that pinion. Even with the missing tooth the mesh was still good, the tooth probably fractured when the brass inserts pulled out of the tranny housing and I just didn’t notice it or couldn’t see it when I reset the mesh. The tooth was there when I reset the mesh so hopefully the missing tooth was just from the previous loose transmission and a new pinion will take care of it.

I’m out of pinions to test with and have to go out of town again for a 10 day work trip so it will be a couple weeks before I can give it another go round. I have lots of pinions and all parts ordered to make a couple new complete transmissions that should be waiting for me when I get back home.

Just bumps in the road…

Here’s a vid of the testing from Saturday with 2 speeds and 30T/24T primary and output gears and 18/26 cb/sg gearing. I was being easy on it on the run until ¾ through the run due to the badly worn owb and only have approx 120’ to stop after I let off. 120 feet sounds like a lot until its @ 60 + and only rwd Engine rpms on that 64.4 mph run calculate to only 23,250 so there was quite a few r’s left in it.


On a funny note: I was offered a nice BMX bicycle and a slightly worn basketball as a trade from a couple kids playing ball at the church ball court

[Oldrcguy]

Looking good, I think you need a wing on the front also lol. Though it seems pretty stable.

[Ckeithnitro]

nice!! she's fast! wicked...

[tphill]

Excellent work and write-up, as always.