Old 408 Motor, Max Amps it can take?

I have a 408 in a 20'' wheel lying around. Dates from about 07 but little used. It is in its basic set up with factory 9 wire feed cable.
Reading that he newer 408's can take many more amps & produce more torque I am wondering if the old and new models are similar inside. I see the motor phase wires are now 2.5mm CSA http://www.crystalyte.com/ Not sure what mine are - but less than this

I am thinking of running 25A @ nom 36v Li ion, see the motor feed cable as a potential limiting factor? Have considered running it sensorless (thus needing only the phase wires - hence then more room for each of these to pass through the axle hole. I always pedal before applying throttle, so the back emf pulses from the direct motor would be there to help it start? I have not used a sensorless controller before - I see some of them have max amps, LV cut off, etc. programmable via an LCD display - this would help in configuring it to my battery

I also have a 400 series clone (Goldenmotor HBM 36) - I married this to a 15A max self learn controller when the original failed. E-Crazyman told me this could take a 500W controller, but at the time I was on SLA so did not take him up on it.

My present home built Li Po4 pack is also limited to 15A max - but am looking at building a Vruzend batt as I have some cells for it & can get more locally. Have already a suitable charger hence the 36V Nom. Also have a 20'' bike with BMX type steel front fork now fitted.
I could equally experiment with the Golden HBM as both 20'' front wheels. The HBM used to peak out @ 16.5 MPH on the flat @ nom 36v,
Areas of doubt are a suitable & affordable controller, & the motor feed wires. Have read up much but still need advice on these points.
Am looking for more torque rather than more speed - sadly on a limited budget. Pete

That's is a really nice old motor. It will handle way more current than that

you can feed it 72v 45a bursts all day long, uphill it will overheat in about 10 minutes though depending on weight and grade

still a great smaller diameter motor

Since you have some room in the axle, you could consider adding a thermometer sensor inside the motor. Like most motors, it can handle a lot for short bursts but the long term limit is dependent on heating. A cheap digital thermometer is only a few dollars.

I have a slightly larger motor on my A2B and hammer it with 50A. It overheats in 10 minutes if I'm climbing slowly up steep hills. If I can keep the speed over about 15mph, the wind cooling keeps up with the heating and it can run until the battery dies.

It seems like it's rare to find a 408 these days. When mounted in a 20-inch wheel, I'd say that's ideal, and now?...you can add ferro fluid, which should really help the heat on hills.

Thanks for the interest, I will likely include the digital thermometer - I have one somewhere - this really only possible if I replace the feed wires. Am I on the right track going sensorless to allow thicker single insulated phase wires? What max temp should I aim to stay below?

I have found an old notebook with xlyte & Golden specs @ 36V nom. I realise the HBM 36 (280 rpm unloaded @ 36v) is actually a 409 clone if not somewhere between the 409 & old 4011. This gets barely warm in general use but the feed wire does warm up on 15A. Very similar to what I have is his present SmartPie SP2X model specs wise - only difference seems the feed wire now does not pass through the axle. He quotes a 25A max for this.

With the hills I have (worst one is 13.3% but not long) I think the HBM is a better bet to try out. I did read that direct motors do not like to be lugged down to below half speed @ full throttle for any length of time (presume back emf drops off- controller then limit on current, & wind cooling less effective). Not sure if they were referring to half unloaded speed or half of the speed @ lightly loaded & up to speed on the flat (this seems to be around 5A @ 36v on any motors I have measured). I do see that Heinsman quote amps for half hour, & amps for 3 min
The 25A battery is about the limit I can run to cost wise, & also an ideal size for the Q128H I one day hope to get.

I wouldn't go sensorless IMO. the 408 may even have an angled stator making it nearly silent and much smoother power delivery when using halls. You will also get better power delivery during take-offs and odd hill climbs

you don't need to cram 8awg wires into the thing if it can only handle 45a spikes you can get away with a 12 or 13awg with a good thin insulation and maybe a layer of heat shrink where it passes thru the axle if needed, the smaller hall wires and the temp wire will fit between the three phases easy since there is going to be a gap around the 3 phases since they are round going into a round hole.

Thanks skeetab, would this conversion table http://tuxgraphics.org/~guido/javascript/awg.html be right in giving me the sizes & metric equivalents of the AWG sizes you recommend? Oddly enough the one you say to use is the one xlyte now use in the 408 but in metric (2.5mm CSA)

I have had the HBM 36 out today climbing some hills, it is on a KU 60 15A max universal controller, motor case no heat at all to the touch, same with KU 60, feed wires slightly warm. Golden factory phase wires are very thin though - probably not even 0.5 mm CSA

Rode also my ATB with Q100 laced into 24'' rear rim, KU 63 15A controller - as a hill climber it is substatially better & all round nicer ride. (same test course exactly) Makes me think of going straight to the Q128H (in same build) I eventually wish for. Fellow member D8veh says they are OK. No doubt the direct motors are good for more miles long term, but I see why the market has gone geared.

Ya looks like the wire it already has installed will handle 30a continuous. Unless something is broken inside there may be no need to even open it. obviously if you are looking to hot rod it then yes you should

sometimes people cut the phases about 6" outside the axle of the hub motor and then use larger gauge from there to the controller. This will cut some resistance out of the mix if you cannot or don't want to fit larger wires thru the axle

Sadly no, mine is an old model with much thinner wires, I am probably going to wait for the Lebroski sensorless as it seems promising. Probably going with the Golden 409 clone at first on this.
I also have an old British TGA crank drive (built into an identical 20'' folder as the Golden hub bike, both have a Sturmey rear 3 speed hub) Surprisingly - the crank drive 1st is just too low, just use 2nd & 3rd on the road, only an advantage if one cannot pedal at all - otherwise the DD hub wins hands down & has been maintenance free since '05 . Crank drive just eats the 18 tooth freewheels that are the basis of it.

I would go with a well chosen hubbie every time, before I owned a crank drive I thought they would be wonderful (my mech background) but in practice they are just a pain - unless you prefer mechanic work to riding. Took all three on a test run this weekend - the Q100 in 24'' rear wheel slightly the edge, close second the Golden 409 in 20'' front, (both off the same Lipo4 pack)