5.5t
 

any body got any thoughts of running a 5.5t in mad rat at club level? gearing
24 pinion 80 spur gear or could you run stock pinion and spur?
:confused:

Personally i think a 5.5 is far too much, a 6.5 or 7.5 should be the fastest you'd want to go :p

erh!
 

I'm a bit new into this but my brother, my friend and I all bought a 5.5t motor and esc,(ezrun) running on just normal ni's (7.2v 3000ma) and on the lowerest setting for take-off (1!) and loosened the slipper off and compressed the spring but this weekend we have all stripped the gears. Not got around to opening them up yet to find the problem but I would say that 5.5t is a little to snappy.

I heard (read) somewhere that for racing you are better off with a 8.5t but running it on 11.1v lipos or 14.8v lipos, this will out proform a 5.5t because it only draws about 3600kv rather than 6000kv, this should give better instant power for jumps, better topspeed and takeoff, ofcourse the downside is the battery is even more £costly£ and more weighty. (p.s this is second hand information and is only what I have read but seems logical)

OHH! Anyone know of any RC shops on the IOW that sell madrat parts, I.E gears ?! Want to get my car running again asap as my lipos have got here today, yay.

I'm running an 8.5T at the moment and have found it pretty spot on in damp conditions. Yesterday was my first outing on dry astro and while the car was good the extra oomph of a 7.5 would have been good. Not sure my reactions are good enouh for a 6.5 or 5.5 - would just get me to the next crash sooned!

iamdigger are you planning to replace the gear with a metal one? it was the ezrun kit i was looking at, just seems you can get 5.5t cheaper then a lower turn motor thought i could power it down using esc

I'd also check that the clubs allow 5.5t... personally I feel that a 5.5 is a bit over the top for anything :)

J.

yer 5.5 is okay for club theres people running 4t in b4s!! just not sure about pinion and spur for 5.5!!

madrat gears idle
 

There's a guy on ebay calling 0planning or planning0 who has a 8.5t kit (motor is rebranded ''BULLSTORM'' but the same) i bought our 5.5t off him and they were a good price. I think the best thing to do is get down a local track and ask about. It what i'd sooner do at the mo.

Hopefully for me it should be the idle gear that is gone, so the thing is if I(me and my brother) just replace the old one at least the problem in contained, i'll just buy 10 or so and swap them out at £2ish a time (I believe people call it and sacrife gear/method so the fault does not contuine down the line and break something weaker and more exspensive, ie Put in a metal one and risk moving the problem onto the whole diff and then having to replace that instead.) Saying that I think i'll try an ally one and see how it goes.

Wheres the best place to buy multiply new replacement parts and get them quick ? I.E not hongkong and not gonna buy a whole rat as it's just the broken gears.

yer your right about the idle gear being suicide part i think, was at my local track yesterday was good but no one running the rat :( i think ebay is good for spare parts there seem to be alot of parts on there or JE spares there sponser on here have alot of parts

do people think the stock 80t an 21t pinon would be any good with 5.5t motor ?

:confused: I wouldn't follow that advice, for racing a 7.5 or 8.5 running a 2S 7.4v lipo is more than enough power for a 2wd car.

yer your right i wouldnt want to run more then 2c also at other clubs its all you can run in 1/10th:thumbsup:

I'm using a 10.5t 4500Kv geared 29/80 on 2s which is hitting somewhere between 45 - 50mph i'd guess.
I'd dread to think what a 5.5t would be like in terms of tyre wear.

I'm the same as damselfly but running a 27t and she is so dam quick

ill let you know on sunday!! think she might be a hand full gunna have to stock up on spares i think :lol:

can i ask where did you get your pinion from? think in gunna need something higher the 21t if you guys are running 27t pinion i think acceleration with 21 pinion will be too much!

I was just stating that it would be better to get a 8.5 / 7.5, and if that is not fast enough buy bigger volt lipos rather than a 5.5t motor and have the best of both worlds. I have a 5.5t and everyone has said the same thing ''oh dear''. Should have got a 8.5 !

Also I have now got my lipos and will fix the car asap and let you folks know how it is. If anyone has a 8.5t and can get hold of a 11.1v lipo I'd (and possible others) would be interested to know what it's like.

I've been considering what adjusting the end points on the throttle would do for, say, a 5.5T (lets say a Novak Ballistic at 7400kv, as they kindly provide a chart here) v a 8.5T (5000kv).

In terms of speed, the extra ~50% revs could be capped by setting max throttle end point to 66%.

This of course doesn't take into account torque differences, which I suppose on the quicker motor could be smoothed out by gearing up, increasing timing (EZRun is sensorless, so only on the motor endbell, if possible), reducing punch on the ESC and putting some negative exponential on the throttle (needs a decent radio for that feature).

what i found
 

Pulled the gearbox apart and found that the green bushed (bearing) on the shaft of the pinion has worn and/or melted the gearbox casing and made the hole it fits in about 2 to 3 mm bigger causing the pinion shaft and gear to move away from the idle gear, there's a small amount of wear to the gears. So going to get a new gearbox case and buy a bearing kit this time.
Then should be able to test the standard gears till destruction and see what gives!

As far as I'm aware you won't be able to use more than a 2s pack if you're racing. As previously stated my 8.5T setup with 4600 40C cells is a great combination of punch and top end in most conditions, I only want more went the track is totally dry, and even then I'd probably only go to 7.5 or may be 6.5.

Being a race-head I've never seen the point of the 'how fast is it mister' argument... as long as the answer is 'fast enough to beat you' I'm good.:lol:

If you want to run 11.1 for bashing it'll be nuts I would think, just make sure you have your slipper and diff set on the money, and keep some spare transmission parts around... chances are you'll need them sooner or later.

I have run a 6.5T on 4500 30C's in my DEX and that's ballistic, my old man reactions are only just good enough to keep up with it. How the big guns run 5.5T is beyond me.

Update
 

Just thought i'd say that my little rat is all good so far. Running a 5.5t ezrun on 5000mah lipo batts, only other upgrades are a standard set of bearings.
Took the car to work today and blusted it around the field(and to portchester indoor track). Goes like stink and the gear box is still in one piece, which is real good, considering I'm using the idle gear thats half worn out.

thanks
 

that is good news that it is working. I have an rc10b4 as well as a rat and for reasons I won't go into I have 5.5 and 6.5 motors to try in them.

Then I have a jump to 10.5 and 13.5 so I'm on the lookout for some 8.5 or something like that to fill the gap. Motors are second hand from the states so they dont cost a bomb.

If I can bash my cars with 5.5 and 6.5 and still get some decent run time and gear them ok then that would be really good.

edit: iamdigger sorry if you mentioned it before but what spur/pinion are you running in that rat with 5.5t?

Mines running good withe the 5.5 t ezrun aswell! Raced it last weekend like ya said goes like stink really pleased with it!!:thumbsup:

spur and pin
 

Just running the standard stuff you get in the box tbh, just with bearing. :)

Can anybody in the know answer my question?
Isn't the turn rating irrelevant here, and just the Kv of importance?
IE- if a 8.5t motor at 4000Kv was compared to a 10t at 4500Kv, wouldn't the 10t motor be faster used with the same voltage pack?
Maybe i'm missing something, but enlightenment would be appreciated.

You'll get more revs, yes, if you gear both the same - however, if the 8.5T has much more torque, you can gear it much higher, making it faster than the 10T anyway.

When calculating speed, you have to account for gearing and rollout (actual circumference of the tyre).

Hi,

Thanks for the response.

I was thinking along the same lines, but wasn't sure.

My velineon motor that was stock on my Traxxas truck ( 10t 3500Kv I believe ) seems real arsekick in comparison to my fusion 10.5t 4500Kv, in that it seems too powerful. I love both motors though, I really do, even though the Kv and turns are very very similar.
Do you know of any reference websites that show motor torques ETC?
Seems that Kv and turns are pretty unimportant until you start reading into the deep spec's.