Which 1950 for 8s lipo?

[Gustav]

I'm trying to decide between the 10 and 11 turn 1950 (1307 and 1188 Kv respectively)
to be run on 8s lipo.

the vehicle in question is the LST using origional tranny with internal ratio 2:1. Diffs are 3.3:1,RTR weight is 12 to 13 lbs.tranny is forward only conversion and without one way bearing.

I have gearing ranging from 18/51 to 28/51 mod 1.(equivalent to 9/51 to 14/51 for a center diff,duh!)so a reasonable range of gearing.

Question is, should i go for the 10 turn which works out at 37,600 rpm or the 11 turn and 34,200 rpm. I hope 45 to 50mph will be a nice speed for this setup.

Other question is will the 36120 be plenty of safety margin in terms of amps or should i get the 36150?

This one will be a little unusual,everything is transverse,tranny,motor and packs.

Thanks for your comments guys.

[Serum]

the 36120 is safe for sure.

Why would you use a 8S setup if you only want to reach 45-50 mph though? is it about runtime?

The lehner motors are weighted loaded. In theory, the 1950/11 should push your truck to the 45 mph with ease on a 51/24 gearing. (with 15cm diameter tires) With those high voltages a lower wind motor will get you a nice and cool setup. (on 3200mAh cells)

My guess is that you will do 45 mph with ease, with a 20-25 minutes runtime.

[Gustav]

Thanks Serum, i was a little conservative i guess with those speeds,i'd like a cool long running setup with excess power on tap.I'd like the ability to top 55mph occasionally.

I was edging towards the 10 turn,i think compared to what i would try with a 2240, maybe i should go with the slightly higher rpm and lower gearing to hit the same speed since it can spool up slightly quicker,i thought maybe the 10 turn might run a little cooler than the 11, as the same speed could be had with slightly lower gearing and so less load.

If it was a 2240 it would have the extra torque to shrug off this extra load,using the torque and lower rpms to accelerate,a little more so than with the 1950. This is all relative of course,i know this is still a big torquey motor,i'm still talking under 38000 rpm.

i'd like to know the likely real rpms under load with these cells(kokam 3200),as i'd like to keep it well below the 42000 limit.would there be much voltage drop under load?,i'd like to keep the real loaded rpm to around 35000.

[RC-Monster Mike]

Either motor would get the job done quite well, actually. I think you will also be well within the rpm limits of the controller with either setup. 8s will provide plenty of power, too!

[Gustav]

Yeah thanks Mike,i know it's splitting hairs really,i like to go with a theory though,hence the jabbering.

I'll ask you to order it as soon as i make my mind up.next few days hopefully.

I'm not in a big hurry really,i need my lathe for this one but it's out of action while i move my workshop/shed.

[Gustav]

Some ginormous mod 1 pinions.they're 8mm bore so i need to make a reducer.The 2:1 ratio is actually an average ratio,in the tranny there are 22 and 23T gears,before the 15/30 bevel gears,that can be run either way round for slightly higher or lower than 2:1.

The 28T pinion is a whopping 44g,it's wider than it needs to be so i can lighten it up a bit.

[coolhandcountry]

Gustav It was a site that sold big mod 1 pinion gears for the 5mm shaft. I can pm you if you are insterested. I lost the site but I think I can find it. Just let me know. Taht away you wouldn't have to modify or get a reducer. Later dude.

[Gustav]

Thanks Coolhand,if you can remember that'd be cool.

I'd need to make a reducer anyway 'cause i'm using 19series 4mm shaft.There's more rotating mass in these though so i'll skinny them up as much as i can in the lathe.

I should have asked Mike if he/his supplier could help but i saw these in stock so i just got them.

I'm kind of experimenting with transverse tranny/motor layout at the moment.After this one i plan to do a flat chassis with the tranny/motor up front with a long rear shaft and the packs in the rear half.

That way the packs only have a drive shaft to saddle rather than a spur, getting the weight much closer to the center line.Kind of like a giant, shaft drive xx4 layout.plus you get zero torque roll with a transverse motor.

Edit;i just thought of another cool thing about transverse motor,i can just flip the diffs and reverse motor direction for either more squat or anti-squat effect of the motor on the chassis-maybe negligable difference but worth a tinker me thinks.

[coolhandcountry]

the site had 5mm 32 pitch gears. So they won't do you much good. Hey did you see what mike can get you. He has a lot of stuff he can get you.

[RC-Monster Mike]

I am not sure how large pinions you need, but I have 24 and 36 tooth gear stock and a lathe to make the pinions any size you want. I also have up to 20 tooth pinions in the store already(5mm bore, though). I have 6mm to 4mm reducers, so I could easily make these fit your 4mm shaft.

[Gustav]

Thanks Mike,if you could cut me a 24T 4mm bore that'd be cool,and a reducer for the 20T.I'll include all this in my e-mail when i order the motor and controller.Thanks.