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Posted (edited)

So, I just finished up the chassis for a tt-02 and I can NOT get it to keep tires on it or take off from a start and not flip into the air. I have a Racing Performer M4 3.5T 10020KV Modified Brushless Motor in it with a HOBBYWING QUICRUN 10BL120 SENSORED 120A ESC (2-3S) and Zeee 2S Lipo 5200mAh. I'm using the Tamiya rear lock block and the tamiya oil-filled diff, Yeah Racing CV shafts, tamiya aluminum driver shaft and cups with Fast Eddy bearings. I've gone through 2 sets of tires and rims because of it. any thoughts?

Edited by Trowa Jakuard
wrong channel

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Let's take this one step at a time, shall we?:

1. 10,020KV motor on an otherwise stock(ish) TT02?

2. Sounds basic, but are you gluing the tires onto the wheels?

3. Why are you using the diff locking block on the rear? I usually hear of it being used for the fronts. Perhaps if you switch the diffs around you'll have a slightly more stable ride.

4. Can you perhaps link a youtube vid of your exploits? For educational purposes of course. I've never seen what a 10,020KV 540 size motor can do on an rc car :D

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Yup, Tires are glued. I had figured the block would work better in the back based on my experience as a regular auto mechanic, so will switch them around and give it a go when I get the new set in. Here's a shot of the girl right now after that second set failed for you. :) It's got a 3s in it for a "Why not?" run

20200709_064643[1].jpg

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Interesting color scheme you have there! I'm currently building up a TT02 Type-S and it will look quite similar when it's finished.

Are you using the Tamiya reinforced touring car tires (53705 - Reinforced Tires - Type B3)? They're made especially to hold shape at higher speeds, and in high temperatures I believe.

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first guess is 10,020 kv motor.........wow

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5 hours ago, Finnsllc said:

first guess is 10,020 kv motor.........wow

And 3S.........

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17 hours ago, Trowa Jakuard said:

I did not know about those

20200709_064700[1].jpg

Looks like your going for it. Stiff Chassis, Savox steering, Race spec battery - good man!. The one big thing missing from this set up is droop adjustment. Not sure if the TT-02 has it - I know the TT-01 did so would assume there is some option somewhere, you might have to loose the lower arm bling but you will gain confidence. Droop helps balance the car and with a 3.5t you need all the help you can get lol.

The races I used to attend where 3.5 mod was run ( forget 3s btw :) ) always used Sorex tyres pre-glued sets - Check out this BRCA racing link about testing tyres for Modified racing https://www.brca.org/sections/10th/10ec/brca-10th-electric-circuit-modified-tyre-amendment. The numbers refer to the temp/grip level. Its very hard as a basher to make sense of these numbers as they are designed for tracks, which by design do not have as much dust, dirt and debris as a carpark/road. Also by default everyone running would be using tyre warmers and tyre additives not that this will affect your car shredding tyres or flipping but the grip levels will be far higher than you can attain. Finally on tyres these meets are limited to 4 tyre sets which everyone in mod will use across approx 8-10 runs, think about that... For you thats throwing away your tyres every 2-3 runs, again that's the cost of running at this level.

As was stated earlier the diff lock should be in the front, but ideally you want a one way spool as opposed to a solid lock. In the rear personally I would put a slipper diff not an oil filled diff but that's me and I am old school. I would also expect to burn up a few slipper diffs while working out what works - how tight and how lubed to go, I would also expect at this level to re-build the slipper every 3-4 runs or so - if I was racing it would be every run.

Can't really help on the gearing, there should be a ballpark provided with your motor esc combo, either way it will be silly fast, most racers would look to get the punch they needed while not topping out on the straight, as I said on your other thread, with 3.5 mod its rare to actually hit top speed on a track, mostly its just the acceleration that's geared to.

If it was mine I would get a 10.5t, re-arrange the diffs, get a few sets of Sorex tyres and then once your used to it put the 3.5 back in.

Good luck!

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Posted (edited)
9 hours ago, Trowa Jakuard said:

I'm gonna sound Dumb here. what's droop?

It a fine adjustment on the suspension arms that limits the amount of movement. Helps in breaking , acceleration and cornering. Everything else needs to be set first though, not like droop will transform a poor set up, its the last 10yards of the mile.

If you think of a 2wd buggy, when it accelerates the front suspension goes to its max travel, full shock extension. If you had droop screws you can adjust how much travel the shock has, 25%, 50%, 75% etc. Droops aim is to limit weight transfer, weight transfer control is the difference between a Sunday driver and a race driver.

Edited by hedge
Correcting a false statement!
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43 minutes ago, hedge said:

It a fine adjustment on the suspension arms that limits the amount of movement. Helps in breaking , acceleration and cornering. Everything else needs to be set first though, not like droop will transform a poor set up, its the last 10yards of the mile.

Droop is only applicable in on road cars, however to visualise it - If you think of a 2wd buggy, when it accelerates the front suspension goes to its max travel, full shock extension. If you had droop screws you can adjust how much travel the shock has, 25%, 50%, 75% etc. Again its NOT for buggys this is just to picture it. Its aim is to limit weight transfer, weight transfer control is the difference between a Sunday driver and a race driver.

I’m struggling to understand why droop is not for buggies? It plays a significant role in BOTH on-road  and off-road applications.

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8 minutes ago, mtbkym01 said:

I’m struggling to understand why droop is not for buggies? It plays a significant role in BOTH on-road  and off-road applications.

I should say fair point!

My personal view however is your in the air too much. Weight transfer control requires the car to be in contact with the earth else you have no control axis unless you incorporate thrusters :) On flat astro tracks then I could see it. Eitherway its the last 10 yards of the mile so little effect, but for a modified car as is being discussed here you need to tweak for every yard in the mile. For a 540 Mabuchi - who cares so under powered the biggest and primary change would be tyres and tyre management - heat and additive. 

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3 minutes ago, hedge said:

I should say fair point!

My personal view however is your in the air too much. Weight transfer control requires the car to be in contact with the earth else you have no control axis unless you incorporate thrusters :) On flat astro tracks then I could see it. Eitherway its the last 10 yards of the mile so little effect, but for a modified car as is being discussed here you need to tweak for every yard in the mile. For a 540 Mabuchi - who cares so under powered the biggest and primary change would be tyres and tyre management - heat and additive. 

I race 1/8 Nitro, both buggy and truggy, and if my droop is not set correctly, both front and rear, to suit the conditions and grip levels, the vehicles are very hard to drive fast. The kits have the adjustments built in, so yep it plays a part and has effect.

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47 minutes ago, mtbkym01 said:

I race 1/8 Nitro, both buggy and truggy, and if my droop is not set correctly, both front and rear, to suit the conditions and grip levels, the vehicles are very hard to drive fast. The kits have the adjustments built in, so yep it plays a part and has effect.

Your right it was a poor statement, I will correct it.

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I can't claim to be good enough to beable to setup my cars...but my 8th nitro buggy has droop screws just like a touring car, and the setup instructions on my 10th buggy says to unscrew the shock eyelet a bit to add droop, and screw it in further to take it away. The HB shock shafts even have lines on them as indicators.

I think its more important in 8th scale though as there is a lot of weight to transfer, and it has proper disc brakes (still find that weird!) which actually work ok, and braking is as importnat as throttle control, unlike 10th blinky racing where its a case of being on the throttle as much as possible.

When one of the fast guys set up my TA07 for me he pretty much removed droop, had a couple mm each end. Its running 21.5T blinky but he said droop setup is really important for mod though.

I always find discussions on droop fascinating. I've read the Hudy guide and played around with my TA07 so get the concept and know how I measure it (even if its different to others as long as its consistent for me then its fine right?) but there are so many differing views. I think a lot of people know how to use it themselves but struggle to help others with it. They don't truly understand it and can't explain it to others even though they use it.

Same with rebound stroke which is on setup sheets. I have no idea about that, asked on rctech and got so many different answers i gave up...so anyone know what that is?

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For me rebound stroke is when you build shocks, without the spring, push the shaft into the body and the rebound stroke is how far it comes back out. You can get positive and negative and none. I used to prefer none on my touring cars, I felt this way my springs where controlling the rebound. Negative may have a use but I don’t know what it is. Positive is generally stated as 25, 50 or 75% and reflects how far back out the shaft comes.

its all adjusted by bleeding the shocks during build.

for my last builds - I don’t race anymore, so just roughly match rebound so front and rear have the same - whatever it is :-)

Hope that makes sense.

 

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I would add that I would prefer to spend the 30 mins it would take me to re-build shocks for specific rebound properties out on the track, my lap times would benefit much more. It goes without saying that set up can only be appreciated if your able to stay on the track lap after lap. Its my experience that even with an empty track people who dont race are normally unable to drive around a track from a rostrum and do the 5 min race time without crashing.

A ballpark track set up for me would include

1) Tyres - Got to be right, on road or off road, sometimes you will find specific tyres for specific events, use this set, change them as frequently as you can afford this way you will have a base line performance to measure all other changes from (no point adjusting your spring rates to get more bite when steering if your tyres are at the end of their life). If you can't find out what tyres to use attend an event and ask the A final drivers what they are using. Always use additive (at a minimum cleaner) for onroad and preferably heat as well but that is expensive. Remember the only thing making your car move, steer, accelerate and brake is the rubber connecting it to the earth.

2) Rear Toe - I would always have this, ball park is 2 degrees absolutely transforms a cars straight line acceleration stability

I would assume oil dampers. The rest, camber, caster, toe, droop, wheelbase, ride height, shock angles, spring rates, rebound, anti-roll bars, oil weight, chassis flex, tyre heat, gear ratio, battery C rating, Nitro %, Glowplug etc can all just be set as standard out of the box recommendation and if you dont have that feature (such as castor) don't worry. Your best way forward is just to learn to drive it, how it is, on a track without crashing or hitting other cars.

 

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28 minutes ago, hedge said:

I would add that I would prefer to spend the 30 mins it would take me to re-build shocks for specific rebound properties out on the track, my lap times would benefit much more. It goes without saying that set up can only be appreciated if your able to stay on the track lap after lap. Its my experience that even with an empty track people who dont race are normally unable to drive around a track from a rostrum and do the 5 min race time without crashing.

A ballpark track set up for me would include

1) Tyres - Got to be right, on road or off road, sometimes you will find specific tyres for specific events, use this set, change them as frequently as you can afford this way you will have a base line performance to measure all other changes from (no point adjusting your spring rates to get more bite when steering if your tyres are at the end of their life). If you can't find out what tyres to use attend an event and ask the A final drivers what they are using. Always use additive (at a minimum cleaner) for onroad and preferably heat as well but that is expensive. Remember the only thing making your car move, steer, accelerate and brake is the rubber connecting it to the earth.

2) Rear Toe - I would always have this, ball park is 2 degrees absolutely transforms a cars straight line acceleration stability

I would assume oil dampers. The rest, camber, caster, toe, droop, wheelbase, ride height, shock angles, spring rates, rebound, anti-roll bars, oil weight, chassis flex, tyre heat, gear ratio, battery C rating, Nitro %, Glowplug etc can all just be set as standard out of the box recommendation and if you dont have that feature (such as castor) don't worry. Your best way forward is just to learn to drive it, how it is, on a track without crashing or hitting other cars.

 

Yes couldn’t agree more on tyres, I’ve seen people chasing set up with toe, camber, spring rates, roll centre adjustments etc, trying to get their car to do a certain thing, when they have the wrong tyre or compound fitted. Tyres will make up about 80% of a good set up imo

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