303LikesXRAY T4'21 Spec
09-06-2021, 03:04 AM
#361
No no, you are right. My initial point was that the motor touch the stock upper deck. But this is another point. Why is the stock motor mount asymmetrical? Not the global design of course, but in term of effects on the chassis. It is fixed on the centerline and the contact surface is symmetric. What did I miss?
09-06-2021, 09:39 AM
#362
No no, you are right. My initial point was that the motor touch the stock upper deck. But this is another point. Why is the stock motor mount asymmetrical? Not the global design of course, but in term of effects on the chassis. It is fixed on the centerline and the contact surface is symmetric. What did I miss?
09-06-2021, 10:09 AM
#363
09-07-2021, 02:11 AM
#364
Weight balance is also important, but it comes just after the flex. If you have a car which can flex normally in right corners but not in left corners, the race will be long, very long lol
09-10-2021, 08:04 AM
#366
A friend recently made me realize that the motor is constraining the torsional flex of the car. As the motor mount is aligned with the upper deck, there is a constraint when you flex in a way that you don't have in the other way.
To solve this issue I had to add 2mm washers between the motor and the motor mount. Washers are pretty small and it makes the risk of the motor moving greater.
How are you guys dealing with this issue? Is everybody using an asymmetric upper deck?
To solve this issue I had to add 2mm washers between the motor and the motor mount. Washers are pretty small and it makes the risk of the motor moving greater.
How are you guys dealing with this issue? Is everybody using an asymmetric upper deck?
Do you have your esc lead under your motor? If yes, could you check this?
09-10-2021, 09:34 AM
#367
Under the motor? It seems very dangerous as they are cutting edges... No my ESC cable is routed above the motor, in a fan shroud I designed.
The issue is very easy to reproduce :
- Put the bearing in the top deck
- Twist the car
The bearing can easily touch the end of the slot on the battery side, but the flex is stopped before it could reach the other end on the motor side. Hence the asymmetrical flex.
Now I'm using a custom chassis to have something stiffer than the original but if I don't put 1mm spacers between the motor and the support, the problem remains.
The issue is very easy to reproduce :
- Put the bearing in the top deck
- Twist the car
The bearing can easily touch the end of the slot on the battery side, but the flex is stopped before it could reach the other end on the motor side. Hence the asymmetrical flex.
Now I'm using a custom chassis to have something stiffer than the original but if I don't put 1mm spacers between the motor and the support, the problem remains.
09-10-2021, 09:46 AM
#368
I use 0.5 mm shims between the motor and the motor mount to try to alleviate some of what you're talking about.
It's unclear how much this really moves during a normal run as it seems you have to twist pretty hard to get the bearing to travel all the way to the edge of the cut out... maybe 0,5mm is enough to not affect the symmetrical flex too much?
It's unclear how much this really moves during a normal run as it seems you have to twist pretty hard to get the bearing to travel all the way to the edge of the cut out... maybe 0,5mm is enough to not affect the symmetrical flex too much?
09-10-2021, 09:49 AM
#369
Under the motor? It seems very dangerous as they are cutting edges... No my ESC cable is routed above the motor, in a fan shroud I designed.
The issue is very easy to reproduce :
- Put the bearing in the top deck
- Twist the car
The bearing can easily touch the end of the slot on the battery side, but the flex is stopped before it could reach the other end on the motor side. Hence the asymmetrical flex.
Now I'm using a custom chassis to have something stiffer than the original but if I don't put 1mm spacers between the motor and the support, the problem remains.
The issue is very easy to reproduce :
- Put the bearing in the top deck
- Twist the car
The bearing can easily touch the end of the slot on the battery side, but the flex is stopped before it could reach the other end on the motor side. Hence the asymmetrical flex.
Now I'm using a custom chassis to have something stiffer than the original but if I don't put 1mm spacers between the motor and the support, the problem remains.
I never twist the car like that (by hand), I just don't see a point in doing it. It sounds like you are twisting a lot. I'm not so sure it even flexes that much on the track, but I could be wrong.
So you, or maybe some others in here are saying with an assymetrical topdeck the bearing doesn't touch the side of the opening when you twist the chassis? Or alternatively, a 2mm shim between the motor and the mount also fixes this? I can't understand how one could affect the other.
(EDIT: What I mean by this is, I don't see how either of the two changes mentioned would solve the issue with the bearing touching the ends of the slot. If you said the motor is touching the topdeck and either of those changes helped, I could see that, but this I don't get.)
09-10-2021, 01:24 PM
#370
Honestly I don't know, I just considered that if Hudy picked this lengh for the long hole in the top deck, it is probably because it is twisting this much. An onboard video would be very interesting.
0.5mm was not enough for me, 1mm is. Now I have to find somebody to cut me a small piece of aluminium to replace shims :-)
0.5mm was not enough for me, 1mm is. Now I have to find somebody to cut me a small piece of aluminium to replace shims :-)
10-01-2021, 03:05 PM
#371
Tech Rookie
hi everyone,
maybe a beginner question, I'm in the process of building my T4, so far, only the central transmission, belts, rear difff and front axle are done. My question is, at this stage, do you expect a fair bit of tension/resistance if you move the spur gear by hand or would you expect it to move freely without resistance at all?
Thank you in advance for all the help.
maybe a beginner question, I'm in the process of building my T4, so far, only the central transmission, belts, rear difff and front axle are done. My question is, at this stage, do you expect a fair bit of tension/resistance if you move the spur gear by hand or would you expect it to move freely without resistance at all?
Thank you in advance for all the help.
10-01-2021, 03:24 PM
#372
Tech Adept
hi everyone,
maybe a beginner question, I'm in the process of building my T4, so far, only the central transmission, belts, rear difff and front axle are done. My question is, at this stage, do you expect a fair bit of tension/resistance if you move the spur gear by hand or would you expect it to move freely without resistance at all?
Thank you in advance for all the help.
maybe a beginner question, I'm in the process of building my T4, so far, only the central transmission, belts, rear difff and front axle are done. My question is, at this stage, do you expect a fair bit of tension/resistance if you move the spur gear by hand or would you expect it to move freely without resistance at all?
Thank you in advance for all the help.
10-01-2021, 04:44 PM
#373
Tech Rookie
10-04-2021, 06:31 AM
#375
