Some tuning options for racers and runners

[mk-Zero]

Thanks!

I'm pretty backed up right now with projects, I need to get the bolt-in mid motor conversion kit ( http://www.rc10talk.com/viewtopic.php?f=35&t=40247 ) done, then I can tackle some of these other ideas

[Garage Hack]

I finally got a chance to have some track time with my Worlds Car equipped with your 25º hubs. The car is just so much fun to drive now. My brushed 27T car was only .2 of a second slower than my 17.5 B4.2. Thanks for providing a good alternative to the crazy expensive Ebay hubs.

ca-rj what do the 25 degree hubs do that makes the car handle better? I am a long time RC guy but know zero about tuning. Any info would be appreciated. Thanks guys!

[JK Racing]

Reducing the caster in the front carriers will give the car more initial turn in, be solid on mid turn, but will drift out more on exit - in my experience. The steering will be more aggressive and change directions better.

[mk-Zero]

So I'm back at this again. I've been spending a lot of time tuning on my B1M test mule and I've come to a couple conclusions. First, it doesn't need to be tuned anything like an RC10, infact quite the opposite. This car has tons of front traction and steering, the challenge is getting the rear hooked up. Second, the tuning options available for RC10's don't work for today's tracks. At least not for a mid motor, and probably not even ideal for a rear.

So ive been spending a lot of time studying setup sheets for modern MM cars like the B5M and the B6 and trying to set things up more like those cars. And so far everything I've tried has really benefited the B1M.

That brings me to these options I'm working on. The first will be a shim set to get front kickup and rear antisquat some adjustability. For now I've printed -5 deg kickup shims for the front and -2 deg antisquat shims for the rear. These will bring those two geometries more in line with modern cars by acheiving 25 deg of kickup and 1 deg of antisquat. I'll probably make these available in a kit that will have -2.5 and -5 shims for kickup (giving 27.5 or 25 deg of kickup) and -1 and -2 for antisquat (giving 2 or 1 deg of antisquat). It will be cheap because they are small thin parts. I may even just print them myself depending on demand...

So far i have been running 1 deg of antisquat on my B1M and it loves it. Next time out i plan to try 25 deg of kickup and see how that goes.

The other idea I've been playing with is adjustable rear toe. I machined a 1.5 deg rear arm mount and plan to make inserts for it that will give either 1.5, 3, or 4 deg of rear toe per side. The B1M loves 3 deg per side, i havent tried 4 yet because it doesnt exist (closest would be 3 deg mounts + 1.5 deg hubs for 4.5 deg toe per side, which i *think* would be too much). The obvious concern with these will be strength. I'm also not sure on a production version if i would machine the AE mounts an then print the inserts, or print both mounts and inserts. We'll see on this one.

[Lonestar]

Really, really cool stuff

[NomadRacer]

Interesting developments, watching with interest if you decide to make some more B1M parts available.

[XLR8]

Hey Brian, would it not be better to increase the rear toe angle at the hub carrier? The problem I see with increasing toe at the arm mount is that it will also increase track width making the CVA/drive cup engagement problem even worse (unless you're willing to sacrifice droop). For instance, I have one of those clever vintage Robinson Racing rear toe angle adjustment kits from bitd (basically, a turn buckle that runs between the rear of two purpose-molded arm mounts) but I can't run CVA's with it because they are too short (works okay with traditional dog bones). Can you print a hub carrier with 2 degrees toe angle or maybe one that will accept inserts? I struggle to find rear grip on my track and adding toe angle can be the solution when I've run out of tire options.

[mk-Zero]

Good point Doug, I'll check it out. On my B1M I'm running B44.1 center rear CVAs in back now with 3 deg arm mounts and have enough engagement in the drives. I'll swap in a World's CVA and see how it looks with the 3 deg mounts. When I was running the World's CVAs before I had the blue spacer and 2 of the thin shims on the inside and it worked okay with 1.5 deg arm mounts and 1.5 deg hubs. I can also look into making hubs with inserts to adjust toe at the hub as well.

I need to get back to working on printed stainless steel outdrives (https://www.rc10talk.com/viewtopic.php?f=35&t=42028&hilit=Stainless+steel+outdrives) and make some extended ones. I've been running the first ones I made for quite a while (since September 2017) now and although they show wear they still work great.

[XLR8]

Yes, changing to B44 CVA's help, moving the blue washer inboard helps, and running a bit less droop also helps with drive cup engagement. However, in addition to altering the toe angle, making custom hub carriers could also provide the opportunity to relocate the hinge pin hole outboard a couple mm's (effectively narrowing overall track width slightly) which could eliminate the need for any of the things I've just listed. Also, the longer outdrives you've mentioned could solve the drive engagement problem regardless of which CVA or arm mount angle is used. Making the changes at the hub carrier offers the opportunity to do both things; to increase drive cup engagement and alter toe angle. In your expert opinion, if I were to submit a carrier design to a commercial printer like Shapeways, do you think any of the materials they offer could hold up under racing conditions? I have very little experience with 3d printed parts so I don't know if the material is strong enough.

[mk-Zero]

I think a rear hub would probably survive well printed in SLS nylon, and even better printed in nylon using HP MJF. I would beef up the hub a bit around the hinge pin vs the stock molded ones though.
I have thought about what you suggested as another way to get toe and help with the CVA engagement. If you want to design it up and print it though go for it. If not I can do it.

[DaveM]

Are these any use?

Team Associated 3 degree rear hubs.

https://www.amainhobbies.com/team-associated-rc10gt-3-rear-hub-carrier-set-asc7358/p43753

[mk-Zero]

Thanks Dave. Could be, but they don't help with the CVA engagement.

[XLR8]

Thanks Brian. I may try to design something and post it here for comment before sending it to a printer. I'd like to go the insert route but this may not leave enough material around the hinge pin.
Dave. I have tested a set of 3 degree carriers and they work great except, when combined with the 1.5 degree arm mounts (4.5 total per side), it can really scrub off a lot of speed and increase tire wear (motor temp probably goes up as well). For my track, 3 degrees total per side seems to be the sweet spot.
Meanwhile, I think Brian's idea to make adjustable arm mounts makes sense. Recall that AE has discontinued the longer B44 CVA bone so drive engagement could be an issue for some of us.

[mk-Zero]

Yeah, the short CVAs is a real bummer. And on top of that the lack of outdrive availability. This is why i want to make extended outdrives, kill two birds with one stone. I also plan to experiment with extending CVA axles. More on that later...
As for adding rear toe at the hub vs the mount, adding it at the mount has the added benefit for the B1M of shortening the wheelbase and getting more rear traction.

[XLR8]

Excellent ideas Brian. All of them would be great products to bring to market. Especially the extended outdrives since the supply of AE outdrives appear to be drying up. I would definitely buy a set.
Oh, and I forgot to mention that I run my RC10's in the short WB configuration to gain a little rear weight bias and to improve drive engagement.