Downhill project motorcycle transmission

Good to clear that up, I was under the impression the motor was labelled incorrectly. The first few runs were indeed in wye and first gear seemed in the regions of 30ish. Hard to tell. Perhaps I should run it in wye again for a while to take some stress off the motor heatwise. She does get HOT. Are there longevity issues running this guy in delta? The water cooling seems more important than ever now!!

The watts meter tops out at 130a and it is most certainly running a fair way over that, hooking up two of these little meters in parallel, as someone suggested, may be the cheap alternative to get a good idea of the amps it's getting rid of. What do you guys think the peak watts could be on a 4t delta?

The rear wheel was always going to give it up at some point and yes it deserved to let go a while back, surprising how it did though.
An interesting comparison. I've got the dyno chart from my street bike in front of me 168.9hp/122nm @ 10000 rpm. The little astro in wye is near double.

Ksithumper perhaps a wye/delta switch could bridge the gap between your 1st and 6th set up if indeed there is a gap. Delta in 1st may be close enough to wye in top
 
I think your motorcycle torque figure at the wheel is actually far higher. Bike dynos measure power at the rear wheel, and an estimated transmission loss is used to correct back to a crankshaft power. Torque is always quoted at the engine speed "xNm at y'000 rpm".

Nevertheless, I think you need a much stronger hub. A pit bike or 50/65cc motocross hub would not be overkill on this beast!

Ecobogan said:
Ksithumper perhaps a wye/delta switch could bridge the gap between your 1st and 6th set up if indeed there is a gap. Delta in 1st may be close enough to wye in top
Click to expand...

Yes, that is one option we plan to try if it does turn out that our little motor bogs down between the 2 gears. The gearbox speed jump is about 2.7:1, so an intermediate wye delta speed change of 1.7 will be ideal. We are a long way from that at present though - at the moment, still making the gearbox casing. We need to borrow a milling machine and couldn't do that this week. Next Tuesday is the plan, when my son has the afternoon off college. Pics will follow. :p

Can anyone tell me if these motors are happy changing wye/delta 'on the fly' ? Presumably it needs a hefty relay and contactors - some heavy currents flowing around. I need to do a forum search!
 
I think you need to sort out the water cooling as there will be very little if any benefit in switching from delta to wye to help keep the motor cool ( it may even be worst )

ksithumper said:
Can anyone tell me if these motors are happy changing wye/delta 'on the fly' ? Presumably it needs a hefty relay and contactors - some heavy currents flowing around. I need to do a forum search!
Click to expand...

There have be a lot of talk about doing this but I don't think I have every seen it implemented by anyone on this forum . Unless someone knows different.
My gut feeling is some controllers ( more than others ) will have a very hard job coping with sorting out the timing if switch from delta to wye on the fly under load.
 
Yeah I was more considering running it in wye again for while, seemed to run cooler. I imagine delta would need more amps to move mass at lower rpm compared to wye
I don't think I will though, I've been delta spoilt and will just cool it properly.
On the dyno readings, all figures are taken at the wheel so I'm told. HP being taken over a time limit, torque being taken as an engine response to load.
Drewjet and Drbass have both successfully run wye/delta switching on both RC and hub motors. Switching on the fly is fine just not under load
 
Ecobogan said:
Yeah I was more considering running it in wye again for while, seemed to run cooler. I imagine delta would need more amps to move mass at lower rpm compared to wye
I don't think I will though, I've been delta spoilt and will just cool it properly.
Click to expand...

I should have also said :
If you don't adjust your mechanical gearing to maintain the same performance when switching from delta to wye then wye will a run little cooler .. but from my experience there is no free ride.
 
what about 2 ESCs, one for each termination? With these tiny COntroller that could make sense, and, although I'm not an Electronic expert (my skills and know-how are amazingly increasing, though), Couldn't see any major issues to do that other than a bit of work for an actuator and the extra cost for another esc. Even the total Heat amount would be shared by the 2 and different programming on the castle software could be done....
Well, sure the same could be made with a single ESC, that was just an Idea, no doubt an option that has been yet covered on ES...
Also, I've only experience with the 4t motor, and real world datas are the best....but working on theory and numbers, seems to me that the 4t in wye is one of the best config to get the the 7Nm peaks that this incredible motor is able to push out, running them at 12s....
What could change the perspective would be to run them at higher voltage I think....A 6t in wye At 72v sensored should be better for the same purposes, and a 4t at that voltage (maybe water cooled and with some work on the Controller side), in wye, should fly enough to not need any re-termination and maybe even gears (for my needs). At 75v My bike should be able of almost 80Kph.....I think.
 
Delta/Wye switching would be perfect for this.

I know of one company that has a switching relay board for this purpose in testing right now. I will keep you guys posted on that. So far it looks good.

Matt
 
recumpence said:
Delta/Wye switching would be perfect for this.

I know of one company that has a switching relay board for this purpose in testing right now. I will keep you guys posted on that. So far it looks good.

Matt
Click to expand...



Are we talking live real time switching here? Like while motor is running, or is there a full stop required?
 
The testing shows that the motor can be running while switching. However, not under load. Above 2 or 3 amps, the controller errors. But, yes, it can be spinning while switching.

When designing this board (I did not design it, but I was part of the discussion for this), I was under the impression the motor would need to be at a dead stop. I am thrilled it can be spinning to switch as long as the load is removed.

Matt
 
Wow this is great news. So all you need to do is ease of the throttle then it will shift?
 
Very cool build, my dual Motoped conversion into electric has me rethinking of such a transmission. Would be easy to find a broken down motor and follow your example. I will be following your progress with great interest.
 
Coming a bit back, about torque values, Just some average datas from an XR650R motard (with some mod) on a Dyno referred to accelerations WOT from 3000rpm in 4th gear on a 160/60-17 motard tire @62rpm per Km/h ratio : XR650R.jpg

Just for reference, the most torquey engine I own, the 12HT on my '87 toy HJ61, produce 315Nm@1800rpm at the output and, with a total reduction ratio in L-1st gear of about 35:1 that means more than 11000Nm delivered to 4x205R16 wheels for a 2700Kg Veicle (full of oils and 5 adults) at 5-6 Kph :mrgreen:
 
So after the rear hub got peckish and ate itself I've got a pair of 40mm 'Spank Stiffy' rims laced to Sunringle hubs via double butted DT Swiss spokes, should do it.

On another note and in my searchings for rim suggestions I inadvertently started a pro/anti E bike fracas on another MTB forum . Some went a little beserk both ways over my bike............and how I ride it.

I don't see the big deal, one test run with no one around and I always pedal past people sedately, it's in my best interests after all. Seems the loose and wild DH scene has its conservative keyboard warrior lurkers.

Bike will be back together again soon enough.
 
Ive been inspired by your build to the point that ive gone and won myself an engine/gearbox on ebay. :shock:
 
NICE WORK!!! What did you end up getting? Ksithumper is definitely taking this a fair bit further than I. mine is carrying some lard for sure and has weight loss potential. Keen to see how you jig it
 
I got an old NSU Quickly 49cc gearbox .
Its already got pedals and drives through a two speed box to a sprocket on the left ,like a motorbike.
Its got a small three plate clutch and it shifts gear via a bar mounted lever.
I was toying with using a sturney archer S3X fixed three speed hub ,turned around to use on the left too .
Chassis wise ,i was gonna use a mongoose ecd downhill frame front triangle ,mounted to the gearbox with alloy plates that would also double as a mounting point for a swing arm.
Time to get the spanners out........ :shock:
 
Hi Dunkenb, Looked at images for the Mongoose ECD.. very interesting! lots of room under the frame triangle for the motor / gearbox.
I would think you will be putting MUCH more torque through the clutch / gearbox than the original motor.. hope it stands up ok.
Looking forward to the build... I think it could be good!
Dave
 
There are some updates, not all of which are particularly nice. The wheel set turned up in the mail the other day and is miles more up to the task, uber gutsy 40mm rims, double butted DT Swiss spokes and Sunringle hubs are working a treat.
The not so awesome news is it's hurt three out of the select four people I've let ride it. A good mate of mine and a very experienced DH and cross country rider is nursing a broken leg after flipping it at a nasty rate of knots. The guy before him made it a good 4 meters before flipping it on the spot and the guy before that flipped it after feeding it too much juice after landing a jump. Not good
All these people I know very well, have bike experience, were thoroughly lectured and given live demos. I've decided no one rides it bar me, not until the controller is reprogrammed and some length is added to the wheel base, it's just too dangerous.
 
Don't get me wrong, I love it and not strangely its violent reputation has spread quickly, intriguing petrol heads far and wide. I'd just like some others to enjoy it too but they all come back in bits.
 
Remember my twin 3210 powered PK-Ripper? That is the first bike I sold to a client ($5,000 for those who want to know). Anyway, that bike was extremely wheelie prone. I flipped it once myself. I told the customer NO-ONE rides it without motocross/dirtbike experience! What does that fool do? He let his WIFE ride it! This is a supermodel level gorgeous woman who competes in "Hot Leg" contests (lucky stiff) :wink: . My phone rings one evening and it is her telling me she just got out of the emergency room with serious damage to her knees from going down on her knees on the pavement. Then she threatened to sue me! At that point I told her I ordered her husband not to let anyone ride it. I also told her "Your husband is rich, I am broke. What can you really gain by suing me anyway?" At that point she apologized and told me she would take it up with him.......

True story.

I build powerful bikes. That particular bike was very hard edged, though. It was my first performance bike. Now I know how to build bikes that are fast, but softer edged.

You are correct to lengthen the wheelbase. That and I would add weight to the front of the bike (battery packs). Adding 15ah to the nose of the bike and adding 3 inches to the wheelbase (preferably lengthening the swing arm) should reduce the wheelie tendency around 50% or so by my estimation.

Matt
 
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