Felony SOLVED? Maybe! My Rear End is as Loose as after a nite at Taco Bell! Why?

[SrC]

Yeah, somethings not right. Your rear camber should be as close to zero as possible, getting all the rubber to contact the pavement. The rear is loose, but shouldn't slide that easily

From what I see his alignment is dead on. That is not the issue. Never was.
I still say, stop eating Taco Hell. You wont get a loose rear end.

More rear droop, less shock preload, give it a try. Keep the fr/rear at 10k also. Or up the front to 15k only.
You have to focus on the front diff also. It affects rear traction also.

 

[J Mitchel]

Thanks all, and SrC...my Felony handled great until I changed the tires from what came on the car to replacements. Night and day, both white Hoons. Even the temps are about the same.
I can't figure what else might have changed other than simply the tires.
So, if I went thinner on the center diff fluid, that would give make the rear get more rpms when there is little traction, but not result in more forward motion. If I went heavier in the center diff fluid, that would stiffen the diff more and if the rear broke loose, the front would be more likely to grip and get forward tractions....do I have that right?

 

[KiTris ExtremeRC]

Thanks all, and SrC...my Felony handled great until I changed the tires from what came on the car to replacements. Night and day, both white Hoons. Even the temps are about the same.
I can't figure what else might have changed other than simply the tires.
So, if I went thinner on the center diff fluid, that would give make the rear get more rpms when there is little traction, but not result in more forward motion. If I went heavier in the center diff fluid, that would stiffen the diff more and if the rear broke loose, the front would be more likely to grip and get forward tractions....do I have that right?

It almost looks like the Infraction with a handbrake once you let off throttle. The only thing that comes to my mind is that the support bearing from the rear driveshaft has gone bad. If it's still good then the tires are the problem. Maybe try some gold Hoons..

 

[J Mitchel]

Thank you for the input. The support bearing spins freely.
I hear what you are saying about the gold hoons. Here is the thing...something changed in the car. We don't know what.
The car ran fine with the original white hoons. It did not need the gold hoons.
Either something is terribly wrong with this specific set of white hoons I have, or there is something wrong with the car. I just don't know what yet.
Again, I really appreciate everyone's help.
Jeff

 

[Tw3ak3d]

Just an FYI, gold Hoons are only good for 3 runs. Can get costly real quick. I still recommend -1 degree max for rear camber. You're probably pushing -4 degrees, so you're only using 50 percent of your rubber, thus 50 percent less traction. Setting mine at -.5 degrees greatly improved the traction in the rear, just wish I could do something about the high speed under steer now.

 

[J Mitchel]

It almost looks like the Infraction with a handbrake once you let off throttle. The only thing that comes to my mind is that the support bearing from the rear driveshaft has gone bad. If it's still good then the tires are the problem. Maybe try some gold Hoons..

KiTris, you got me thinking about that handbrake and drag...and you know what? The same day I changed the tires I noticed that the motor was a bit loose in its mount so I pushed it in really tight and tightened it back up. Trying to think what could be causing drag....and I put the center diff back today, (same fluid...cannot find 100 or 500k fluid anywhere near me right now to change it) and while I could not find in the manual how to set the pinion mesh, I used the Traxxas method of a piece of paper in between the pinion and spur gear.
I ran it again today after adjusting that mesh spacing and it is improved. Not good. Not right. But better than it was.
When I can get 500k fluid, I will try that in the center diff, but other than that...I am out of ideas.
I did set the camber back to 0 degrees afterwards with no noticeable change from -2 degrees.
Thanks,
Jeff

 

[Mr.Vylan]

BTW- I've been waiting for Gold Hoons I ordered from HH back in October. Is there another source that has them available?

 

[KiTris ExtremeRC]

KiTris, you got me thinking about that handbrake and drag...and you know what? The same day I changed the tires I noticed that the motor was a bit loose in its mount so I pushed it in really tight and tightened it back up. Trying to think what could be causing drag....and I put the center diff back today, (same fluid...cannot find 100 or 500k fluid anywhere near me right now to change it) and while I could not find in the manual how to set the pinion mesh, I used the Traxxas method of a piece of paper in between the pinion and spur gear.
I ran it again today after adjusting that mesh spacing and it is improved. Not good. Not right. But better than it was.
When I can get 500k fluid, I will try that in the center diff, but other than that...I am out of ideas.
I did set the camber back to 0 degrees afterwards with no noticeable change from -2 degrees.
Thanks,
Jeff

I have to test out your "driving style" soon. I usually drive my Felony a lot faster so I have no comparison if my rear end behaves the same way as yours does. But it really looks like something makes the rear wheels stop a little bit faster / more resistance than the front ones (hand brake effect), once you let off throttle. Would be interesting to see how the car behaves if you keep the same amount of throttle during turning. But I'm almost certain that the Felony tires are a different compound than the normal sized Hoons. Or at least because of their different size they behave quite different but I'm pretty sure there is a difference in the compound, although Arrma assured me they are the same. Little bit off topic but I tried to do a burnout with the Felony (to make the tires smoke) and they didn't smoke or at least very little (mostly the front ones did). With my Infraction I just have to give it a short burst of throttle and all 4 tires smoke instantly. What I'm trying to say is that maybe your new set is also a harder/different compound than the old one, it just has to be, if everything else is the same

 

[Mr.Vylan]

I have to test out your "driving style" soon. I usually drive my Felony a lot faster so I have no comparison if my rear end behaves the same way as yours does. But it really looks like something makes the rear wheels stop a little bit faster / more resistance than the front ones (hand brake effect), once you let off throttle. Would be interesting to see how the car behaves if you keep the same amount of throttle during turning. But I'm almost certain that the Felony tires are a different compound than the normal sized Hoons. Or at least because of their different size they behave quite different but I'm pretty sure there is a difference in the compound, although Arrma assured me they are the same. Little bit off topic but I tried to do a burnout with the Felony (to make the tires smoke) and they didn't smoke or at least very little (mostly the front ones did). With my Infraction I just have to give it a short burst of throttle and all 4 tires smoke instantly. What I'm trying to say is that maybe your new set is also a harder/different compound than the old one, it just has to be, if everything else is the same

I have the same comments regarding speed and how that affects the rear sliding out. I drive faster than the example in the video and therefore my drifting and overall traction is much different, I can certainly slide the rear out easily when I want. But the rear sliding out is not an issue based on throttle control.

see the sliding in my video here.

 

[J Mitchel]

I have to test out your "driving style" soon. I usually drive my Felony a lot faster so I have no comparison if my rear end behaves the same way as yours does. But it really looks like something makes the rear wheels stop a little bit faster / more resistance than the front ones (hand brake effect), once you let off throttle. Would be interesting to see how the car behaves if you keep the same amount of throttle during turning. But I'm almost certain that the Felony tires are a different compound than the normal sized Hoons. Or at least because of their different size they behave quite different but I'm pretty sure there is a difference in the compound, although Arrma assured me they are the same. Little bit off topic but I tried to do a burnout with the Felony (to make the tires smoke) and they didn't smoke or at least very little (mostly the front ones did). With my Infraction I just have to give it a short burst of throttle and all 4 tires smoke instantly. What I'm trying to say is that maybe your new set is also a harder/different compound than the old one, it just has to be, if everything else is the same

Again, really appreciate your response.
I cannot get smoke either, but the tires do heat up running against a curb.
I have a few more sets of the rears, new in the bags, so I will try to swap them out and see. The fronts grip fine, so I think it is the compound as well. I gave the old tires to a friend to make a beer coozy for his garage. I might see if I can get them back and even though they are worn out, see if running them makes a difference. If the car goes back to "normal" then I have my answer.

That said, I finally found a localish hobby shop that has 500k in stock. I am going to pick up some today and try that instead of the 100k in the center diff. I think, because I am new to this I don't know for sure, that the thicker fluid should get the front to pull more if the rear is losing traction and that might help with the spinning out.

Driving style: I most often run in a large school lot that has an L shape. I run the shape of the L and at the corners of the the L, where the two straights meet, I come off the throttle a bit, transferring weight to the front as I enter the corner to induce a rear skid, come back on the throttle at about 1/3 of the way through the turn and steer with the throttle through the rest of the turn with the tail hanging out, steering in opposite lock to the skid. The throttle at this point is likely at about 40-60%....enough to maintain forward momentum and steering but no so much as to lose all traction.

I run with the AVC set to a low level. I find that the AVC reduces throttle in turns and I don't care for that. I also have recently come to realize that the AVC is tunable and that I can make some adjustments that may also help with the throttle drop in turns and the skidding, but I have not started messing with that yet. I want to get the car back to where I had it, running well, before I adjust something else.

 

[KiTris ExtremeRC]

Again, really appreciate your response.
I cannot get smoke either, but the tires do heat up running against a curb.
I have a few more sets of the rears, new in the bags, so I will try to swap them out and see. The fronts grip fine, so I think it is the compound as well. I gave the old tires to a friend to make a beer coozy for his garage. I might see if I can get them back and even though they are worn out, see if running them makes a difference. If the car goes back to "normal" then I have my answer.

That said, I finally found a localish hobby shop that has 500k in stock. I am going to pick up some today and try that instead of the 100k in the center diff. I think, because I am new to this I don't know for sure, that the thicker fluid should get the front to pull more if the rear is losing traction and that might help with the spinning out.

Driving style: I most often run in a large school lot that has an L shape. I run the shape of the L and at the corners of the the L, where the two straights meet, I come off the throttle a bit, transferring weight to the front as I enter the corner to induce a rear skid, come back on the throttle at about 1/3 of the way through the turn and steer with the throttle through the rest of the turn with the tail hanging out, steering in opposite lock to the skid. The throttle at this point is likely at about 40-60%....enough to maintain forward momentum and steering but no so much as to lose all traction.

I run with the AVC set to a low level. I find that the AVC reduces throttle in turns and I don't care for that. I also have recently come to realize that the AVC is tunable and that I can make some adjustments that may also help with the throttle drop in turns and the skidding, but I have not started messing with that yet. I want to get the car back to where I had it, running well, before I adjust something else.

Switching back to the old tires would be quite interesting. Let us know how it goes.
Actually the thicker diff fluid will reduce the front wheels spinning up as much under load. So both rear and front tires will spin at the same speed. It could still improve your handling situation but if the car ran fine with the stock 100K, it should do it now as well.
I don't use AVC because I have a different remote on mine. Certainly helps if you have a little bit less experience. But it should usually prevent the back end from sliding out. You could turn it off for a run just to see how it handles without. Maybe somethings wrong with the AVC which I don't think but you never know

 

[Boggs3010]

I tried all sorts of things . Height, springs camber and weight, new tires. Hot temps outside cooler temps outside same issue. I give and it is now mostly for bigger areas. (huge parking lots) Now printing 3d parts that will add balanced weight in the rear will test in a few days.

 

[Liquid SSSnake]

What holes are the rear camber links in? If they're in the wrong places it can cause snap oversteer.

Also, try unhooking the rear swaybar and see how you like it.

 

[SrC]

Just an FYI, gold Hoons are only good for 3 runs. Can get costly real quick. I still recommend -1 degree max for rear camber. You're probably pushing -4 degrees, so you're only using 50 percent of your rubber, thus 50 percent less traction. Setting mine at -.5 degrees greatly improved the traction in the rear, just wish I could do something about the high speed under steer now.

The above relates to roll center and actually does apply. However the OP hasn't changed his roll center at the rear. Camber interacts with Roll center setup.
Also, I find that New tires take a while to break in. I mentioned this before. And if temps are cold, the diff oils WILL thicken up depending, and even thin out as you run. Traction will change slightly, back and forth as you run, then the rig rests and so forth.. I noticed this on my Infr. and Lim. also. There are many variables with the OP's issue.

 

[SrC]

What holes are the rear camber links in? If they're in the wrong places it can cause snap oversteer.

Also, try unhooking the rear swaybar and see how you like it.

^^^ Agree about the camber link being in the correct position. This will change Roll center. OP hasn't changed that however on his Fel.. He just swapped out tires.

I wouldn't disconnect the sway bars, but I would dial them in. Guaranty they are not correct and dialed in L to R evenly, Both front and rear. None are out the box.
ALL Sway bars need to be adjusted. No one talks about this. It seems to be a lost topic with the advent of all RTR's and never discussed in any Arrma manuals.
I would look up video's on the proper way to do just this.
Everyone seems focused on the rear end here. Don't overlook the chassis front end also.
These are pics of my Lim's rear camber links position. Same for my Infr. Fel. should be identical this. Just for reference. FWIW. And if their position WAS changed, the Camber would be so wacked out anyway and obvious. The OP's pictures already show correct Camber. Camber Alignment is not the issue IMHO.

 

[SrC]

Again, really appreciate your response.
I cannot get smoke either, but the tires do heat up running against a curb.
I have a few more sets of the rears, new in the bags, so I will try to swap them out and see. The fronts grip fine, so I think it is the compound as well. I gave the old tires to a friend to make a beer coozy for his garage. I might see if I can get them back and even though they are worn out, see if running them makes a difference. If the car goes back to "normal" then I have my answer.

That said, I finally found a localish hobby shop that has 500k in stock. I am going to pick up some today and try that instead of the 100k in the center diff. I think, because I am new to this I don't know for sure, that the thicker fluid should get the front to pull more if the rear is losing traction and that might help with the spinning out.

Driving style: I most often run in a large school lot that has an L shape. I run the shape of the L and at the corners of the the L, where the two straights meet, I come off the throttle a bit, transferring weight to the front as I enter the corner to induce a rear skid, come back on the throttle at about 1/3 of the way through the turn and steer with the throttle through the rest of the turn with the tail hanging out, steering in opposite lock to the skid. The throttle at this point is likely at about 40-60%....enough to maintain forward momentum and steering but no so much as to lose all traction.

I run with the AVC set to a low level. I find that the AVC reduces throttle in turns and I don't care for that. I also have recently come to realize that the AVC is tunable and that I can make some adjustments that may also help with the throttle drop in turns and the skidding, but I have not started messing with that yet. I want to get the car back to where I had it, running well, before I adjust something else.

If you are using the stock RTR AVC Radio, I don't see how you are getting Active Throttle control at all. ST AVC is the only feature you are getting.
If you are using a DX5C radio for instance with that RX, then Full AVC, both ST and TH. control works. You only have one AVC ST control with the Stock AVC radio. "Steering Gain". My DX5C has both ST Gain, Throttle Gain and most importantly a Priority Trim that controls both together. 3 controls total for full AVC functionality. The stock RTR radio is a "Light" version of AVC.
I don't like AVC and disable it completely for my Lim during a radio Bind.. ( using my DX5C) My Infr. I use The stock DX2E with AVC but find myself turning ST gain down very much. BTW, when changing out tires and and different chassis settings, a ST AVC adjustment is almost always imperative. AVC is not set and forget. Different surfaces, speeds and distances require it to be adjusted every time. Or it just works against you. I prefer to leave AVC out of the equation most of the time or you will be chasing a ghost trying to figure out why the rig is acting weird and inconsistent from time to time.

 

[J Mitchel]

To all: Again, super helpful and I am really appreciative.
Stock RTR radio. I have heard about the priority trim and was thinking maybe I could adjust that, but I think you are saying my radio doesn't do it.
I will say that with the AVC set to 1/4 turn from off, or more, if I turn the steering wheel with power on, the power drops. The tighter the turn, the more power drops. And I mean throttle diminishes, not wheelspin.
I got the original tires back from my friend, but now it is 40 degrees and raining for the next few days...so no testing for a bit.
As far as I know, all the settings on the car are factory, except rear camber, which I dialed to zero. I do think I had a degree or two negative previously, and my understanding is that for other than straight line....some negative camber is desired. But in the interest of figuring this out, I am back to zero camber.
Thanks,
Jeff
Portland, OR

 

[SrC]

^^^ Zero camber is desired, even for speed running.
You using The DX2E radio. Or the newer one? None of the RTR radios offer more than one AVC control. Just ST gain. The manual is clear on this. Look at your radio. If you are using a BT upgrade module on that radio maybe its available. I just know that TH AVC doesn't occur on my Infr. using the DX2E radio never did. There would have to be a Gain knob for it to work properly. Like with my DX5C multi model radio. If there is TH and ST AVC conrolled with just one Gain trim. That's kind of lame. Again from having full AVC controls on the DX5C. ST and TH gain must be separate. I would never use it any other way.
Read up on your RTR manual. Mine states nothing regarding TH AVC. It's only discussed in my DX5C manuall and the Rx manual.
Maybe someone else will chime in to counter my opinion??? ?‍
I think its an important topic, not to hijack your thread here..

 

[Liquid SSSnake]

^^^ Agree about the camber link being in the correct position. This will change Roll center. OP hasn't changed that however on his Fel.. He just swapped out tires.

I wouldn't disconnect the sway bars, but I would dial them in. Guaranty they are not correct and dialed in L to R evenly, Both front and rear. None are out the box.
ALL Sway bars need to be adjusted. No one talks about this. It seems to be a lost topic with the advent of all RTR's and never discussed in any Arrma manuals.
I would look up video's on the proper way to do just this.
Everyone seems focused on the rear end here. Don't overlook the chassis front end also.
These are pics of my Lim's rear camber links position. Same for my Infr. Fel. should be identical this. Just for reference. FWIW. And if their position WAS changed, the Camber would be so wacked out anyway and obvious. The OP's pictures already show correct Camber. Camber Alignment is not the issue IMHO.

I put mine on the upper hole (closest to the tire) that should give the best general driving position. From what I understood from researching roll center is that you almost never want the hub link to be lower than the shock tower/bulkhead side. It's ok to put the bulkhead side link in the lower hole for tuning. The camber would only change drastically if you move it inner/outer without adjusting the turnbuckle.

(I couldn't remember when I took the hub off it I accidentally put them it the lower holes or if it came like that. The expanded parts view was no help.... I drove it anyway, then put them in the upper holes, I like it better personally.) Then I cynically thought they want us to tear up tires, Lol

I disconnected the rear bar because its thicker than the front... I thought stock was backwards. I'm gonna buy an assortment of springs, sway bars, and fine tune them last. I'm no expert but I like to tune the suspension to handle rather that changing diff fluids or band aid the stickiest widest tires, I tuned my 4 Tec for two years, my only other RC, now I got one of these.

Also the ground temps are likely much colder than what they were in late fall regardless of the air temp and sunshine, that will throw things off too.

 

[SrC]

I agree with your reasoning. ? Yeah the blow up wont show actual stock position. The concept of roll center can minimize tire scrub and lost traction when adjusting. It's not just the angle of the camber link but its ultimate length as well. Its a viable adjustment if you understand it. The adjustments are there. The RTR manual will never discuss it anywhere. It is an often overlooked adjustment. But can really dial in any rig to an advantage. If it is not understood. It should be left alone.