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View Full Version : Chasing Right Turn Grab/Let Go Issue


Blf
2016.11.17, 01:11 PM
Wanted to bounce this off you guys ---- one of our 4 F1s has been exhibiting this kind of grab, let go, grab, let go etc. when turning at speed on the track ..... mainly to the right. I've literally switched out EVERTHING and can't for the life of me figure it out.

When you go for it at limit into a hard right turn it almost chatters but feels like its turning like a tank, grab, let go, grab let go.

Check out vid of just doing hard rights in a circle and you can hear what Im talking about....

https://youtu.be/Sv3PX9yPv0s

Its driving us nuts trying to diagnose

Evil_Sephiroth
2016.11.17, 01:30 PM
maybe a contact/wire that work/don't work under lateral load?

TeeSquared
2016.11.17, 01:38 PM
Do the front wheels hit the wing support? I've had erratic handling issues on F1s before, and the problem was often that at an extreme steering angle, the front tire would hit the back of the front wing support.

Check that the front suspension isn't loose or one of the king pin carriers isn't cracked.

Blf
2016.11.17, 02:00 PM
Yep --- I switicged out the front knuckes (PN 1.5), tie rod, tires, did nice filing of the uprights to give me great front suspension travel/clearance.

From above comment, I was wondering if its the motor or/wire under load? Its nuts that the other 3 (with same parts ) don't do this? Is it tweak, the board, the motor?

That's all I can think of?

It seems like the inside of the front tires is awfully close to the end s of the tie rods but other cars don't exhibit that?

Evil_Sephiroth
2016.11.17, 02:41 PM
Yep --- I switicged out the front knuckes (PN 1.5), tie rod, tires, did nice filing of the uprights to give me great front suspension travel/clearance.

From above comment, I was wondering if its the motor or/wire under load? Its nuts that the other 3 (with same parts ) don't do this? Is it tweak, the board, the motor?

That's all I can think of?

It seems like the inside of the front tires is awfully close to the end s of the tie rods but other cars don't exhibit that?

It can be a little of chassis warping...maybe the chassis of that car is a little bended to the point you can't clearly see but where -1mm is important you have friction.

Plus i think that, even if Mini-Z are really light when you run the car on the floor you can have a little more torsion, then, what don't touch the tie rod when you have the car in your hand can have problem during running.


False contact under lateral load can happen, not common, but check wire soldering on the board.

Sorry again for my english i hope you get my ideas anyway

Blf
2016.11.17, 03:08 PM
English is great! Thanks

I'm just puzzled as to why this one (not the other 3) is doing it.

Im going to swap out the king pins and the motor at this point I think.

What to look for on the board that would cause this? Again, its great in a straight line, just when you push it into a turn hard.

TeeSquared
2016.11.17, 03:20 PM
It seems like the inside of the front tires is awfully close to the end s of the tie rods but other cars don't exhibit that?

Add some shims behind the front wheels to push them away from the tie rods. They can hit them when the car is on the track and the wheels are subject to loading. Turn the wheels to their extremes and spin the wheels. Put the car on the track with the wheels turned over and push it by hand. Can you feel the snagging? Take the front wing off entirely, as well as the bottom chassis decoration and then try it.

I seriously doubt the problem is electrical. Could be wrong but it looks/sounds like something is catching on the front tires.

Blf
2016.11.17, 04:01 PM
Tee --- I did just that before you replied. Spacers if you will, on the front knuckle axels behind the wheels the keep the insides of the tires clear of the PN Tie rod end --- I was thinking that could be the only thing making this happen but no..... :confused:

Evil_Sephiroth
2016.11.17, 04:16 PM
it's sort of stupid but you can try putting fresh colour on part that don't rotate, make 1-2 turn where the problem happen and then see if and where you have friction.

Also Tee said that it doesn't sound like an electrical problem, and i agree after rewatching the video, but if you want to try when you are desperate try switching the board with one from your others car.

The place to watch closely are where the wires are soldered on the board and the engine wires...

From what i see on my MA-20 kyosho welding are pretty little and maybe can be cracked inside.

EMU
2016.11.30, 05:38 PM
Can't view the video, says it was removed.

What motor mount, t-plate/side plate, and differential are you using?

Most f1 exhibit issues steering to the left due to rear ends issues... But it could still be a rear end issue.

Could also be servo saver or servo gears.

How old is this f1? What electronics are on the car, have you adjusted any of the ics settings?

If you are using a ball differential, do you have a stock one that you can try. And if it is ball differential, and Kyosho or older atomic, do you have the plates glued to the diff halves? Is there a small amount of lateral play between the diff and motor mount?

Another thing to check, is to drive without the body on, if it stops then, the issue is with damper/motor wire clearance of the body. What rear damper is being used?

Over 90% of f1 handling issues come from the rear end, body clearance, and differential. There are quite a few tricks that I have used to make f1 cars handle beautifully...

Can you post a few pics of the car? Body on side, rear, top, and top body off? The side and rear would be great if level with table to see ground clearances.

Blf
2016.12.05, 12:32 AM
It's a kyosho ball diff with sanded plates and ceramic balls but I always wondered why the atomic diff I have has the "d" shape to the plates so the key into the diff halves. Kyosho carbon side plates

Do we really have to superglue the diff halves? What's the deal with that and why is it free spinning from factory?

It's a MF015 without pn mm pn 1.5 knuckles, PN 0 toe tie rod, kyosho dds, sanded grinded out rear for clearance jus? in case, PN KS compone from feo to and marka 10 on the rear.

EMU
2016.12.05, 08:35 AM
Kyosho diffs are not keyed, and can lead to spinning. if you don't want to glue, use a heavy sticky grease between the rings and the halves to hold them in place a bit better. if you glue, a thin glue works better, and just a couple of drops will make a big difference. You want to ensure that the ring is sitting flat in the diff half. As you insert the ring with glue or grease, give it a good twist to spread the glue and it will sit flat. if it doesn't, remove, clean and reinstall.

Does the spur have a bearing? Kyosho diff halves are not designed for the bearing, and may need to be clearances slightly for use with the bearing. A little work with sandpaper, circular motion on a flat surface can be enough to clear the bearing.

Many ball differentials, especially Kyosho do not key they diff rings. This actually gives them better balance, as the diff had the same mass throughout the rotation. The difference is very minor. The Kyosho diff rings are some of the best in the business, as they are harder material than most others. Once a Kyosho diff is built up, there is considerably greater time between rebuilds compared to other manufacturer's. With ceramic balls, I find that a thin grease, with minimal quantity works best.

With a PN mount, check the clearance between the body and where the side plates screw into the mount (the bottom rear corner of the body just behind the mounting clips). Some bodies will limit the travel and need to be trimmed for adequate travel.



edit: Now on a PC. To clarify, when gluing the diff rings in place. Or gluing tires in place... never apply the glue directly from the bottle to the surface to be glued. One drop will be too much, in one specific location. Get a small cup, like a mouthwash cup, or a small disposable dish... put a couple drops of glue on it, and use a small pick, like a plastic toothpick to dip and apply. You will have much more precise application, and much less error. Nothing is worse than getting glue somewhere that it really shouldnt be.

I chased this issue for quite a while in the past, and it turned out to be the diff rings slipping. The Kyosho diff is one of the best, due to the quality of the rings, however, not being locked in place leads to many headaches. Larger scale diffs typically do not need glue to hold them in place, since there is more space for the grease to sit between the rings and the diff halves. At this scale, there just isnt enough material for the grease to sit easily... So a little glue will do the trick. Also, never run the diff dry, even with ceramic balls. The rings still need the grease, and the grease will trap some of the debris and prevent it from entering the bearing track on the rings.

If you rebuild the differential, and find it to be a little notchy, and unsmooth, then swap out the shaft bearing in the spur side diff half.