272LikesSerpent Project 4-X
11-21-2016, 06:09 AM - Wikipost
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08-31-2017, 03:58 PM
#361
I had the same experience when running outside. The rear end washed out. In modified this is not a good thing. Bought a T4 2017 and lowered my 5 min time with 6s first run. The 4X can be very fast for some in certain situations but also very difficult in other. I feel that the setup window is small, where the car actually works, compared to a more convential touring car. Many people here prefers the Eryx 4.0 outside instead.
Some suggestions for asphalt. I Never run the h blocks, too stiff. Try running 2 or 1mm under the arm mounts front and rear to raise the roll centre. Try running 2/3 mm of caster shims behind the rear top arms, this also creates more rear steer. I'm running 2k2hole orange heave front/ rear and 2k zero hole roll shocks grey or green rear springs andq green or purple front.
Can you tell me why parallel lower and upper arms is a good thing?
In my testing outdoors the car is loose at the rear because it is rolling too much to the extent it's rolling off the rear tyre. It needs to be much stiffer in roll. Hence the blank pistons and 2-3k oil in the roll dampers. I'm up to using blues and grey springs in the roll dampers and the car is much better. I don't have the loose rear-end anymore in high speed corners. It just seems the harder I go the better the car gets. Bear in mind I'm running all the latest parts. I'm actually 1mm less shims under the rear upper arm mounts too. The car is getting better every run.
I'm pleased to see that there are some people that agree with me.
By the way, I'm not sure that the RC are too deep in the ground. On my car, lower and upper arms are parallel with 2mm shim. With that, it is geometrically impossible that the RC is in the ground.
A little bit of help by RC Crew Chief would be nice for that.
The lower arms inserts are also buggering me. On my VBC, I have small shims in the rear and nothing in the front. Does anybody already tried to mount the rear arms support middle-up instead of middle-low?
Removing the H is a really bad idea as it will create some flex points. I'm considering using standoffs (from PC motherboard) instead of the H.
By the way, I'm not sure that the RC are too deep in the ground. On my car, lower and upper arms are parallel with 2mm shim. With that, it is geometrically impossible that the RC is in the ground.
A little bit of help by RC Crew Chief would be nice for that.
The lower arms inserts are also buggering me. On my VBC, I have small shims in the rear and nothing in the front. Does anybody already tried to mount the rear arms support middle-up instead of middle-low?
Removing the H is a really bad idea as it will create some flex points. I'm considering using standoffs (from PC motherboard) instead of the H.
Removing H is inevitable if I want to change the roll center but yeah your idea is not bad putting an improvised pole instead. Or I could grind down the H a little to create some room.
08-31-2017, 07:49 PM
#362
Tech Fanatic
iTrader: (1)
In my testing outdoors the car is loose at the rear because it is rolling too much to the extent it's rolling off the rear tyre. It needs to be much stiffer in roll. Hence the blank pistons and 2-3k oil in the roll dampers. I'm up to using blues and grey springs in the roll dampers and the car is much better. I don't have the loose rear-end anymore in high speed corners. It just seems the harder I go the better the car gets. Bear in mind I'm running all the latest parts. I'm actually 1mm less shims under the rear upper arm mounts too. The car is getting better every run.
I just need to try these new parts once I've finished experimenting with the XQ1
09-01-2017, 03:43 AM
#363
I agree with Wagwan, raising the lower arms is a better thing to do if you want to raise roll centres without causing much trouble with part interference or modding parts, use high roll centre bushings exclusively. Then tune with upper shims if the roll centre is too high (the car will start to slide more at a certain point) to bring the roll centre a bit back. if there is too much camber gain then upper arm length has to be longer. Only those two things are needed, everything else will need a bit of tuning but it's easy to address.
Having the arms parallel(and more importantly parallel to ground) is good in a sense of the roll centre will be at ground level, zero height. That is perfect on the front as you have caster and camber gain to keep one from having too little camber once the car rolls and roll bars and roll dampers to limit if there is too much roll. In the rear one just runs one(or two) mm less on the upper arm support and presto, one item ticked to get a balanced car in driving manners.
One more thing, the Ackerman is "wrong". The way it's set means there's a lot of off centre steering, compounding the issue of the rear end. Using the rearmost hole on the wheel side will give less turnbuckle angle and less Ackerman. Everything lost can be achieved using other setup options.
In conclusion, the roll centre bushings need a change (don't change the upper shims without changing the bushings or you are making it more difficult to tune), the upper shims might need a change(depends on how the car will respond because the arm geometry mimics 1:1 race car engineering, which is a big plus),roll will be geometrically stiffer so a change in dampening might be needed and there is no need to change heave,only if the car dips or squats too much that it puts the tire in a non desirable alignment.
Will post something like this in my FB page. https://www.facebook.com/Hephaestus-...6808876003561/
Having the arms parallel(and more importantly parallel to ground) is good in a sense of the roll centre will be at ground level, zero height. That is perfect on the front as you have caster and camber gain to keep one from having too little camber once the car rolls and roll bars and roll dampers to limit if there is too much roll. In the rear one just runs one(or two) mm less on the upper arm support and presto, one item ticked to get a balanced car in driving manners.
One more thing, the Ackerman is "wrong". The way it's set means there's a lot of off centre steering, compounding the issue of the rear end. Using the rearmost hole on the wheel side will give less turnbuckle angle and less Ackerman. Everything lost can be achieved using other setup options.
In conclusion, the roll centre bushings need a change (don't change the upper shims without changing the bushings or you are making it more difficult to tune), the upper shims might need a change(depends on how the car will respond because the arm geometry mimics 1:1 race car engineering, which is a big plus),roll will be geometrically stiffer so a change in dampening might be needed and there is no need to change heave,only if the car dips or squats too much that it puts the tire in a non desirable alignment.
Will post something like this in my FB page. https://www.facebook.com/Hephaestus-...6808876003561/
09-01-2017, 03:44 AM
#364
I hope you're wrong. I'll get back to you once I have more experience with this still-funky-looking machine.
Thanks. Everybody seems to go with 0 hole roll dampers for sure. I'll try it next time.
Yo! I know it's not alignment in my case. Next time, I'll remove H in the rear to try more camber gain and higher roll center. Since the default RRS(parallel to chassis) is set to maximum already there's nothing more to gain but certainly it's something worthwhile to play with a bit more.
Can you tell me why parallel lower and upper arms is a good thing?
Will try the harder roll damping for sure. Not sure about new parts yet. So much more to test w/o those new parts yet
I didn't measure it using a tool so I could be wrong. I'll take a look again tonight but it seemed certainly very low to me. Especially when the arms are almost parallel, it's next to impossible to determine the crossing point unless somebody holds one freaky long ruler while the other holds the other.
Removing H is inevitable if I want to change the roll center but yeah your idea is not bad putting an improvised pole instead. Or I could grind down the H a little to create some room.
Thanks. Everybody seems to go with 0 hole roll dampers for sure. I'll try it next time.
Yo! I know it's not alignment in my case. Next time, I'll remove H in the rear to try more camber gain and higher roll center. Since the default RRS(parallel to chassis) is set to maximum already there's nothing more to gain but certainly it's something worthwhile to play with a bit more.
Can you tell me why parallel lower and upper arms is a good thing?
Will try the harder roll damping for sure. Not sure about new parts yet. So much more to test w/o those new parts yet
I didn't measure it using a tool so I could be wrong. I'll take a look again tonight but it seemed certainly very low to me. Especially when the arms are almost parallel, it's next to impossible to determine the crossing point unless somebody holds one freaky long ruler while the other holds the other.
Removing H is inevitable if I want to change the roll center but yeah your idea is not bad putting an improvised pole instead. Or I could grind down the H a little to create some room.
09-07-2017, 10:44 AM
#365
When you guys run the VTD and want to run 2mm shims for the upper roll center, are you changing both the front and rear roll center at the same time? Otherwise if you just change one end the top deck is off no?
09-07-2017, 01:39 PM
#366
So it will be the quest for roll centers...
I'm pretty sure that this car also have a very low center of mass, so it means that the roll center must be lower if you want to have the same roll momentum, just a matter of geometry.
The only thing I'm sure for that moment is that with an horizontal neutral roll axis, the cas is not efficient, you have understeering and a slipping rear at the same time!
Now I have to try lower the front roll center or higher the rear roll center to reach a good balance.
I'm pretty sure that this car also have a very low center of mass, so it means that the roll center must be lower if you want to have the same roll momentum, just a matter of geometry.
The only thing I'm sure for that moment is that with an horizontal neutral roll axis, the cas is not efficient, you have understeering and a slipping rear at the same time!
Now I have to try lower the front roll center or higher the rear roll center to reach a good balance.
09-07-2017, 03:26 PM
#367
So it will be the quest for roll centers...
I'm pretty sure that this car also have a very low center of mass, so it means that the roll center must be lower if you want to have the same roll momentum, just a matter of geometry.
The only thing I'm sure for that moment is that with an horizontal neutral roll axis, the cas is not efficient, you have understeering and a slipping rear at the same time!
Now I have to try lower the front roll center or higher the rear roll center to reach a good balance.
I'm pretty sure that this car also have a very low center of mass, so it means that the roll center must be lower if you want to have the same roll momentum, just a matter of geometry.
The only thing I'm sure for that moment is that with an horizontal neutral roll axis, the cas is not efficient, you have understeering and a slipping rear at the same time!
Now I have to try lower the front roll center or higher the rear roll center to reach a good balance.
09-07-2017, 04:02 PM
#368
So it will be the quest for roll centers...
I'm pretty sure that this car also have a very low center of mass, so it means that the roll center must be lower if you want to have the same roll momentum, just a matter of geometry.
The only thing I'm sure for that moment is that with an horizontal neutral roll axis, the cas is not efficient, you have understeering and a slipping rear at the same time!
Now I have to try lower the front roll center or higher the rear roll center to reach a good balance.
I'm pretty sure that this car also have a very low center of mass, so it means that the roll center must be lower if you want to have the same roll momentum, just a matter of geometry.
The only thing I'm sure for that moment is that with an horizontal neutral roll axis, the cas is not efficient, you have understeering and a slipping rear at the same time!
Now I have to try lower the front roll center or higher the rear roll center to reach a good balance.
Last edited by snuvet75; 09-08-2017 at 12:13 PM.
09-07-2017, 09:14 PM
#370
09-07-2017, 09:18 PM
#371
Tech Fanatic
iTrader: (1)
You need to balance the CG with the RC and then also consider the roll sensitivity given damping and spring rates on top of the CG and RC.
It's all a bit complicated for me, so only thing I do is go by that golden rule of change one thing at a time and try it out on track.
I for sure run higher rear roll centre by using 2mm rc shims all around and run mid-high pills on the rear and stay with mid-low on the front.
09-07-2017, 10:39 PM
#372
Lower CG is not necessarily better - look at the BD7'16
You need to balance the CG with the RC and then also consider the roll sensitivity given damping and spring rates on top of the CG and RC.
It's all a bit complicated for me, so only thing I do is go by that golden rule of change one thing at a time and try it out on track.
I for sure run higher rear roll centre by using 2mm rc shims all around and run mid-high pills on the rear and stay with mid-low on the front.
You need to balance the CG with the RC and then also consider the roll sensitivity given damping and spring rates on top of the CG and RC.
It's all a bit complicated for me, so only thing I do is go by that golden rule of change one thing at a time and try it out on track.
I for sure run higher rear roll centre by using 2mm rc shims all around and run mid-high pills on the rear and stay with mid-low on the front.
09-07-2017, 11:17 PM
#373
Tech Fanatic
iTrader: (1)
BD7'16 was a dog of a car compared to its '14 and '15 variants. Primary change? Lower CG, smaller shocks.
I'm not saying it's not better - I'm saying that lower CG needs to be considered amongst other things too. If you change just the CG, but leave roll center and all your springs and damping the same, you'll end up with a much stiffer car setup that probably won't work.
I'm not saying it's not better - I'm saying that lower CG needs to be considered amongst other things too. If you change just the CG, but leave roll center and all your springs and damping the same, you'll end up with a much stiffer car setup that probably won't work.
09-08-2017, 11:58 AM
#374
Thats not what I mean. I was just pointing the fact that the front and the rear RC are rarely at the same height.
09-08-2017, 12:12 PM
#375
BD7'16 was a dog of a car compared to its '14 and '15 variants. Primary change? Lower CG, smaller shocks.
I'm not saying it's not better - I'm saying that lower CG needs to be considered amongst other things too. If you change just the CG, but leave roll center and all your springs and damping the same, you'll end up with a much stiffer car setup that probably won't work.
I'm not saying it's not better - I'm saying that lower CG needs to be considered amongst other things too. If you change just the CG, but leave roll center and all your springs and damping the same, you'll end up with a much stiffer car setup that probably won't work.
