Need help in the horsepower wars

[MadInventor 3886]

A friend and I have been having a little friendly competition with some drag racing. A while ago we both bought 8.5Turn ezrun brushless systems. He's running an associated B4 geared up ridiculously with 2.2" rear wheels and some wickedly sticky rear road tyres (HPI or pro line I think), on an 8.4V 4500Mah NiMH. I've been running a thundershot with a 15T pinion, some HPI wheels with mini spikes, and a 10.8VNi-Cad. Even with the extra 2 cells, he's still easily outstripping me. (I'e got an SCT speedo so it can take the extra volts)

The weekend before last I picked up a TT-01 at a boot sale for £20, so I ballraced it, put on some alloy suspension I already had as the standard wishbones were very tight, and made up a 10.8V NimH battery as a triangle pack to go in it. I stuffed in the largest pinion that would fit (A 22T) and thought, no worries, I'll blow him into the weeds with this. The first problem was the centre drive shaft ballooning so much it touched a battery wire and the friction caused the propshaft to melt. Also sudden acceleration caused the tyres to simply fly off the wheels. Flat out the car was just slower than the B4, but it's so twitchy its pretty well impossible to control (I have fitted TA05 oil shocks). I've glued on the tyres and am going to either make a steel propshaft, or buy an aluminium one. I'm undecided where to go from here. I could get a smaller spur gear for the TT-01 to gear it up and make it even faster, but it's pretty uncontrollable at the moment, and I think the high rotational speed of the standard drive shafts might cause the pins to fly out of the dogbones. This is only a problem on the rear as the fronts have after market UJs fitted.

Basically my question is, do I try to make the TT-01 go faster (I suspect it is already doing in excess of 50mph), or do I just sell it on and buy something more suitable. If I do go for something else I've got to be able to fit a 8-9 cell pack in it (I don't like to play fair ). The thundershot is definetly more stable at these sorts of speeds than the TT-01, but I think it's at the limit of it's performance envelope, as if I try to gear it up further I encounter cogging and the motor gets hot, plus the TT-01 seems to be closer to the performance of the B4.

Any suggestions ??

(I'm not buying a B4 and fitting a 9.6V battery, that would be admitting defeat )

[TenzoR 65]

Sell it and get yourself a cheap ta05. You can gear that easier than a shaft drive car, plus the belt drive will handle the speed much nicer.

[Leethal Driver 86]

Sorry can't help, but that had me chuckling all the way through

Really want to know how you get on! Keep us updated, back to the track race blog style...."this week I shoehorned 15 cells in with a 25T pinion at it just blew up on the start line".

Wife just called me a loser for laughing at my own post too.

[Percymon 2185]

Buy a used 5.5T motor and pretend its still the 8.5T ???

[MadInventor 3886]

Sorry can't help, but that had me chuckling all the way through

Really want to know how you get on! Keep us updated, back to the track race blog style...."this week I shoehorned 15 cells in with a 25T pinion at it just blew up on the start line".

Wife just called me a loser for laughing at my own post too.

Your reply made me laugh so much it made my eyes water

Will post some links to how it goes on here. The B4 had a camera mounted on it last time we went out so if I can get the vids I will post on youtube for everyone to see. The thing is so fast the front tyres baloon at speed. They've only been glued on with 'spot welds', so the tyres go to a star shape. It's quite funny to watch on video, the front suspension motoring up and down despite the fact it's running on smooth tarmac.

I've just ordered an aluminium propshaft and a 55T spur gear. If that doesn't work I'll flog it and try something else.

[MadInventor 3886]

Sell it and get yourself a cheap ta05. You can gear that easier than a shaft drive car, plus the belt drive will handle the speed much nicer.

I'd have thought the brushless motor would have stretched the belts badly ?? Also when I raced my first TT-01 against a friends TA05 there didn't seem to be any speed difference between the two, if anything the TT-01 seemed a bit faster. I do take on board what you say about making it easier to gear up though, I'll give it serious consideration. Was also thinking possibly along the lines of maybe a fast 2wd tamiya buggy, or maybe turning to the dark side and going for a schumacher cat or cougar ???

TT-01

Melted propshaft

With the 10.8 fitted. It's got to be fast, it's running on 3 sticks of dynamite

[HunterZero 77]

Yeah that plastic not-so-fantastic prop shaft has got to go. You need the alu one. Replacing the stock plastic drive shafts with steel UJs is a good idea for handling that power.

Aluminium suspension arms are useless, they just add unsprung weight, go back to using the plastic ones.

A TA05 belt drive is surprisingly robust. Breaking belts is very rare. The belts do stretch a little when you take off, but the car just feels like it's accelerating out of a slingshot. With belt drive, you also don't get the weird drifting torque effects from the longitudinal rotating mass that you get in a shaft drive car. The TA05 is a lot more adjustable and should be more precise around corners compared to the TT-01, and more stable at speed.

The advantage that the TT-01 has is that it's light. So it has an advantage in a straight line.

LiPo batteries are very light, you might be able to shoehorn a 3S LiPo in there with a bit of dremeling. Should give more punch. You'll need a LiPo compatible charger and a low voltage cut-off.

- James

[redzone 212]

Get a 3s 11.1v lipo & blow him into the weeds lol

[Origineelreclamebord 45]

Get a 3s 11.1v lipo & blow him into the weeds lol

+1: Go LiPo and away are your troubles, for several reasons. For one, LiPos can handle the brushless power better. Secondly the batteries are lighter, so your car will be lighter as well. And lastly, due to the lighter battery, the chassis will have a better weight balance from left to right, which should help stability

However, the biggest steps will be made by replacing the TT01 for somethig that's designed to handle such speeds. A TA05 would work very well I think (given you stay on the road that is ), an F104 (if your running grounds are really flat), a TRF201 (you could call that admitting defeat as well as it's almost an RC10B4 copy, but still better than buying a B4 itself), a DB01 of TRF511 (they might be slightly heavy to take on a 2WD onroad, but they sure beat it around a track and with on surfaces with lower grip).

[Yonez 180]

+1: Go LiPo and away are your troubles, for several reasons. For one, LiPos can handle the brushless power better. Secondly the batteries are lighter, so your car will be lighter as well. And lastly, due to the lighter battery, the chassis will have a better weight balance from left to right, which should help stability

However, the biggest steps will be made by replacing the TT01 for somethig that's designed to handle such speeds. A TA05 would work very well I think (given you stay on the road that is ), an F104 (if your running grounds are really flat), a TRF201 (you could call that admitting defeat as well as it's almost an RC10B4 copy, but still better than buying a B4 itself), a DB01 of TRF511 (they might be slightly heavy to take on a 2WD onroad, but they sure beat it around a track and with on surfaces with lower grip).

If you have the cash and want to win, why not get a TRF417?

It's Tamiya, so it can't be admitting defeat. And it's an insane machine. I so want one

[TenzoR 65]

I'd have thought the brushless motor would have stretched the belts badly ?? Also when I raced my first TT-01 against a friends TA05 there didn't seem to be any speed difference between the two, if anything the TT-01 seemed a bit faster. I do take on board what you say about making it easier to gear up though, I'll give it serious consideration. Was also thinking possibly along the lines of maybe a fast 2wd tamiya buggy, or maybe turning to the dark side and going for a schumacher cat or cougar ???

TT-01

There's a reason why all the top r/c touring chassis are belt drive. They handle the power very nicely. The shaft drive will give you better off the line acceleration assuming you don't torque steer (which you will if you are using a really powerful motor).

If you want to win, get an used TA05 (any version). Gear it for top speed. Get grippier tire. The rest is how you setup the car to handle such high speed.

Also, get a highdown force body (protoform) and reinforce the front end so the car does not flip up by making sure the front wheel arch stays the same shape. A couple speed runs by a couple local club members got both their TRF417 to flip up at the end of the straight when they didn`t reinforce the body. I don`t recall what gearing they are running but they were running along the lines of boosted brushless 3.5T.

Hope that helps. Stay with a 4WD. You can put the power down much easier than 2wd (F1 included).

[SteelRat 46]

Only thing I'll say about 3S is I'm not sure the EZRun ESCs can handle it. Think they'll only handle 2S.

[MadInventor 3886]

Thanks for all the input guys.

I suspect the next step will be a 3S Lipo. I'm using an EzRun SCT speedo with the EzRun motor, not the normal 60A speedo, and I think it's good for 3S, but will have to check.

I've got a spur gear kit and an aluminium prop shaft on order for the TT-01, to see how much I can max it out with the existing electronics. I suspect as has been stated already that the torque steer will be a problem, but I'll try it anyway just to see what happens. Total outlay on the TT-01 so far has only been about £30, as I had all the other bits already. A TRF417 is going to be too rich for this project, it really is just a bit of friendly competition, I can just about justify a LiPo battery as I already have a compatible charger, and maybe at a push a 5.5T motor, if the speedo will handle it, but I'll have investigate that further. At the moment we are racing on tarmac, but it's a bit rough in places so a F103 is out of the question.

I think that Lipo and a 5.5T motor will be too much for the TT-01 though, so I suspect I will shortly be looking for a second hand TA-05.

I have to disagree with the comment about the alloy wishbones though. On my first TT-01 2003 Skyline GTR the plastic wishbones had quite a lot of slop in them and the alloy bits nicely removed all this slop. On the one I just bought (A merc of some sort) the wishbones were so tight in their mounts they would not move freely, so I had to fit the alloy ones to give a free movement to them. Granted the alloy bits might be slightly heavier (I'll have to weigh them and see what the difference is) but they make the suspension work so much more smoothly.

It's amazing the variability in build quality of standard componenents from model to model.

I'm also getting the videos from the first run tonight

[axemandavva 0]

Any suggestions ??

(I'm not buying a B4 and fitting a 9.6V battery, that would be admitting defeat )

TT01 you need an alloy propshaft or the plastic one will happily try to remove your radio gear for you as you have found. A steal pinion would be a must too. The old TL01 has a steel drive shaft which can handle the power.

For ultimate speed you need a brushless motor and lipo as has been said, then then the only problem is using the power.

Most top end touring cars have ball diffs, which tend to slip when you`re going for ultimate drag race type speed - even with 4wd.

I suppose if you`re running somewhere very flat and grippy and smooth and you have a bit of foam tyre additive you could try something like this

[WillyChang 1816]

you need belted slicks with proper inserts... anything else will balloon up & you're gripping on knifeedge

[TenzoR 65]

TT01 you need an alloy propshaft or the plastic one will happily try to remove your radio gear for you as you have found. A steal pinion would be a must too. The old TL01 has a steel drive shaft which can handle the power.

For ultimate speed you need a brushless motor and lipo as has been said, then then the only problem is using the power.

Most top end touring cars have ball diffs, which tend to slip when you`re going for ultimate drag race type speed - even with 4wd.

I suppose if you`re running somewhere very flat and grippy and smooth and you have a bit of foam tyre additive you could try something like this

Most top end touring cars have gear diffs now (with fluids).

[Origineelreclamebord 45]

If you have the cash and want to win, why not get a TRF417?

It's Tamiya, so it can't be admitting defeat. And it's an insane machine. I so want one

Well... Because the TA05 will be sufficient to bring the B4 to it's knees... so you could brag on that 'Tamiya has even better cars to show they are the best' Though I do really like the idea of a TRF417...

Only thing I'll say about 3S is I'm not sure the EZRun ESCs can handle it. Think they'll only handle 2S.

You have a point there... A puff of smoke is spectacular, but the only thing going fast is the money disappearing from your bank account... Perhaps it will do however if you turn the punch down a bit?

[axemandavva 0]

Most top end touring cars have gear diffs now (with fluids).

I stand corrected, it`s been a few years since I`ve been to the track.

Many of those around at the time the TT01 and TL01 (schumachers, yokomos) do have ball diffs which slip when you go silly with the power - but other then that they can be great cars for bashing because they`re not too expensive and tend to handle better then a stock TT01 or TL01.

[TenzoR 65]

I stand corrected, it`s been a few years since I`ve been to the track.

Many of those around at the time the TT01 and TL01 (schumachers, yokomos) do have ball diffs which slip when you go silly with the power - but other then that they can be great cars for bashing because they`re not too expensive and tend to handle better then a stock TT01 or TL01.

The gear diffs in TT01 and TL01 are not adjustable. They are considered open differentials.

The newer type of gear diffs in the higher touring cars can be fluid filled (similar to 1/8 buggies). You can thicker fluid you want the gear diff to be tighter (e.g. tightening the diff balls) or thinner fluid if you want a more smooth diff. However, unlike ball diffs, the gear diff will never slip. The added benefit of gear diff is the less maintenance and much easier to build a proper diff. No more guessing "how tight" that ball diff should be.

I'm sure these fluid gear diff will trickle down to all the chassis sooner or later. This hobby is getting easier and easier, with brushless, lipos and now gear diff

[axemandavva 0]

The newer type of gear diffs in the higher touring cars can be fluid filled (similar to 1/8 buggies). You can thicker fluid you want the gear diff to be tighter (e.g. tightening the diff balls) or thinner fluid if you want a more smooth diff. However, unlike ball diffs, the gear diff will never slip. The added benefit of gear diff is the less maintenance and much easier to build a proper diff. No more guessing "how tight" that ball diff should be.

Neat. I`ve not come across these diffs before but they definitely sound like progress. I guess the only advantage some ball diffs might have is that it is quicker and easier to get in there and tighten the screw if it is slipping too much.

[mike_o 35]

Madinventor,

would you consider going 2WD (like the B4) to get rid of 40-50% of the transmission loss? With your set-up, it should earn you at least 5km/h. If acceleration is important, go for RWD, if stability is is important, go for FWD.

Going RWD on the Thundershot should be easy and because of the transversely mounted motor and longitudinally mounted propshaft, the loss reduction may be even greater than 50%. Loosing propshaft, front diff, and front dogbones will save weight.

Consider also lowering the chassis to get the (rear) dogbones close to horisontal with batteries in.

Keep us posted, please :-)

Mike

PS: In case you embark on the 2WD conversion road, have a look at this thread

RWD TA-04

[SteelRat 46]

You have a point there... A puff of smoke is spectacular, but the only thing going fast is the money disappearing from your bank account... Perhaps it will do however if you turn the punch down a bit?

I've just got a 6000kv EZRun system for my Firestorm that includes the v2 edition of the ESC, and it quite clearly says on the side that will handle 2-3S LiPo, so I was wrong about that. I was sure that they were only rated for 2S, but maybe whatever had changed with version 2 includes 3S support?

[bakaguyjean 7]

Buy a drag car or a pan car. and use good tires. It will kill anything with a gearbox.

[Yonez 180]

Neat. I`ve not come across these diffs before but they definitely sound like progress. I guess the only advantage some ball diffs might have is that it is quicker and easier to get in there and tighten the screw if it is slipping too much.

Yeah, but then gear diffs don't slip.

But if you mean limited slip adjustment when one wheel has nothing to grab on to, then yes.

By the way: Is there any spool that will fit into the rear gearbox of either car? Spools don't slip and for going straight ahead they should be sufficient.

[TamiyaDan 8]

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