Lonestar's RC10 OIN - turned B1M Racing chronicles (Race #3 on P.7)

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Re: Lonestar's RC10 OIN - turned B1M Racing chronicles (Race #2 on P.5)

Post by XLR8 »

I have the same problem with my SC10. Replaced virtually every pivot, pin, cup and bearing but nothing has worked. It's due, as you've explained, to the alignment of the steering components at full lock. Anyway, I hate how that car handles and I've stopped running it for that reason. Probably should post it on ebay and just turn the page.

"It was probably of lesser importance on RM cars (even the B4) but as MM architecture started taking push out of the equation and load the front wheels more, this becomes an issue." - Lonestar

I think you're spot-on! I'd like to go back and have a look at the steering systems used in newer cars with high front weight bias (i.e B5M to B64D) and see how they compare to vintage.
Doug

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Re: Lonestar's RC10 OIN - turned B1M Racing chronicles (Race #2 on P.5)

Post by jwscab »

I don't think you will ever get rid of a wobbly inside wheel in 2WD(rwd) in a 'rear' steer config. That inner front wheel is lightly loaded and all over the place. The link is unloaded and all of the clearances will cause it to wander because it's almost a parallel connection and the link is under compression/tension cyclically. Changes in toe-in/out I think can improve it to skew the loading one way or the other.

I notice this readily apparently in my GTO, which is a 'rear' steer car. all the other gm cars I have are 'front steer'. the GTO has a noticeable 'wiggle' in the steering wheel I think due to the toe changing dynamically and putting the steering tie rods in compression and tension. it's hard to explain without a bunch of math and it's hard to find research on it, but I believe it to be the case. In some full size trucks, they alleviate this oscillation with a damper on the tire-rod connected to the chassis.

this is going to sound wacky, but if you had a strong servo, you could add a small torsion spring to the spindle/hub so it preloads the spindle, and when that inside wheel is turned in, the spring would prevent the spindle from loading/unloading. essentially removing the backlash.

I can see the 'flipped' steering rack helping slightly, but not completely curing the problem, because the inner link gets closer to the arm when fully locked, so the link is less parallel to the kingpin.

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Re: Lonestar's RC10 OIN - turned B1M Racing chronicles (Race #2 on P.5)

Post by XLR8 »

The only RC car I have that's front steer is the CW Dominator. Do you suppose Landgraff designed it that way to address the subject linkage alignment problems? I just assumed he applied front steer to avoid routing steering links through the drive chain but maybe there was more to it. Just curious; have you noted any unusual tire wear patterns on your GTO that could be attributed to the steering system or is just the occasional wheel-shake in a hard turn?

EDIT: Oops, sorry the SCX10 and TF2 are also front steer but they don't count.
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Re: Lonestar's RC10 OIN - turned B1M Racing chronicles (Race #2 on P.5)

Post by jwscab »

the GTO is a front end nightmare to be honest.

there are a few problems with the front end that need to be addressed in stock form.

the front 'A' arm is more like a mustang II, a lower control arm and a lower control link that form the 'A'. The front link has a mushy liquid filled rubber bushing that cause tire wear issues. So aftermarket polyurethane bushing replacement is a huge improvement, but once the mush is gone, you notice the shimmy in the wheel.

second, the factory strut bearing and bushing assembly is very likely blown out due to very excessive strapping to the cars when they were sent via carrier ship over the ocean. So those need to be replaced, as they will also lead to tire wear issues, particularly with inner edge wear.

couple all that with the fact that the original tire size (monaro) and strut fabrication was OK, but they increased the tread width and some brand tires' sidewalls can contact the strut body and cause tire failures. My solution was a 1/8" wheel spacer and proper torque sequence and torque specs.

Now, once all that is complete, the car still has a cyclic hum at certain speeds. here is the WEIRD part. it's almost like a tuned oscillation because you can be driving along in a straight line, and the wheel will have just the slightest wiggle at 12 0'clock. Now take a sweeping turn for a few seconds, like a easy highway curve. Now the front wheels are turning different speeds and end up 'clocked' differently. Now in a straight line, you will notice a more pronounced shimmy. repeat around another bend and it goes away.

I've learned to just ignore it because even though I hate lots of the issues with the car, it is SUPER fun to drive and easy to drive long distance because those seats are super comfy.

in case you are interested, but slightly off topic, to complete the chassis tuning, I also added rear subframe poly bushings and a diff insert. I also had alignment issues on the rear tires, but there is no real adjustment, they are a trailing arm design with fixed camber essentially, so I replaced the coil springs with stock height aftermarket ones designed to improve the sag (again, from strapping to the ship decks). Bringing the rear back up improves the camber angle and restores tire alignment.

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Re: Lonestar's RC10 OIN - turned B1M Racing chronicles (Race #2 on P.5)

Post by Lonestar »

XLR8 wrote: Thu Jan 18, 2018 9:17 am I have the same problem with my SC10. Replaced virtually every pivot, pin, cup and bearing but nothing has worked. It's due, as you've explained, to the alignment of the steering components at full lock.
yes - that's because the SC10 basically is an inflated B4... same shortcomings.
jwscab wrote: Thu Jan 18, 2018 9:51 am this is going to sound wacky, but if you had a strong servo, you could add a small torsion spring to the spindle/hub so it preloads the spindle, and when that inside wheel is turned in, the spring would prevent the spindle from loading/unloading. essentially removing the backlash.
that's actually pretty smart... but you'd want the torsipn spring to not apply "steering" pressure... only way I can think about doing this is by fixing a spring on the c-hub that would apply "straightening" pressure. Even torsion-wise, how would you have something that forces it "open" instead of "close"?

Ha- we're moving to 1:1 discussions now...

btw, feels good to have this turning into a technical discussion :)
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Re: Lonestar's RC10 OIN - turned B1M Racing chronicles (Race #2 on P.5)

Post by works92 »

Pretty nice result, without practicing the night before and considering all your wrenching
Some drivers gonna be under pressure on the next round :mrgreen:

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Re: Lonestar's RC10 OIN - turned B1M Racing chronicles (Race #2 on P.5)

Post by Lonestar »

works92 wrote: Sat Jan 20, 2018 6:15 am Pretty nice result, without practicing the night before and considering all your wrenching
Some drivers gonna be under pressure on the next round :mrgreen:
Thanks :mrgreen:

the thing is, I doubt I'll be able to better it next time, because now I'm not going there for fun any more, but with a purpose instead... this is typically when all hell breaks loose :mrgreen:
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Re: Lonestar's RC10 OIN - turned B1M Racing chronicles (Race #2 on P.5)

Post by Lonestar »

A bit of short on time here, but trying to move on, still...

For the car's last race in a couple of weeks (will be a B6.1 this fall instead! Enough of this retromod-running BS :mrgreen: ), I want to fix a few things to finish in style, including that darn steering which I still think is disfunctional.

So, time to pull out the runner CE Stealth and pillage some more parts (for a good cause):
DonorCar10CEStealth.jpg
This car sports a proper, vintage, pre-Jeff A&L steering from the glory days!
SteeringOnDonor.jpg
Disassembly time... and I find out that there are stands in the steering assembly, meaning shorty screws are needed.
holdingstands onDonor.jpg
So I have to pull out the dremel and cut some BHS screws on the B1M - remember I'm on LWB setting, so the far away holes in the nose plate aren't countersunk:
ShortyScrewsBHS.jpg
Before bolting it on, a few comparison shots that show (1) the LWB of the B1M and (2) how the steering/ackermann look better on the A&L setup (more lock AND more differential steering!). Still, once raced, the B1M will get its RPM steering back, or maybe a worlds re-re steering, really, as it will end its life as a mild runner (if runner at all)

B1MvsCE.jpg
SteeringDifferences.jpg
More to come when I have more time... which is proving a challenge these days :roll:
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Re: Lonestar's RC10 OIN - turned B1M Racing chronicles (Race #2 on P.5)

Post by Lonestar »

I could log in a couple of hours on the car these past few days.

Steering now fully installed... with a mix-match of turnbuckles to make it all work, as the tecnas I had were too long since now the connecting bar reaches further.
Installed.jpg
It's a bit dirty because, again, it's my runner's. the lo-profile nylon nut threads are stripped, I'm waiting for some new ones anytime now :)

But I'm happy to report that it's better in EVERY aspect:
- less wobble on the inside wheel
- more throw on the outside wheel
- differential steering that looks better
- less toe variations on compression/extension... should make it for a more predictable car.

Then I pulled the transmission out, to replace the motor. While I was at it, I cleaned and rebuilt the diff (lots of motor spray involved). I just LOVE the stealth diff... it's such a treat to rebuild, it feels so good right after, and I've done so many over the years that I can do them with my eyes closed and one hand tied in the back :mrgreen: Overall the diff had 16 packs and was feeling slightly gritty, but it could have done one more race no problem. But given how crappy accessibility is on this car, I figured out, what the heck.

Gotta love that compact design from CPD :)
Trans.jpg
I also noticed that the V2 slipper I had installed (can't remember whether I had mentioned I had upgraded from a V1), the spring was dangerously close to the tub... As I don't have scr8p's dremeling skills, I did this in a few seconds.
Notched.jpg
That car might be a runner, it's still ugly that way - so the sharpie comes to the rescue :D
Sharpied.jpg
On the to-do list now:
- reinstall motor, solder
- drill front shock tower to mount shocks somewhat higher (have tons of front droop atm)
- fix that darn rear UJ with a proper retainer clip (the shring wrap was pierced by the pin...)
- Cut a couple of screws that are too long
- probably more stuff that I keep forgetting

I was thinking that at this stage, the only RC10 parts left on the car are the battery boxes, the main tub (front plate is 10T :D ), the diff... it's totally ridiculous, I have never ever spent that much time (and money, now that I think about it...) on a car to get it to run properly. Even when I shelf-engineered my crawler from a TLT-1 years ago, it wasn't that time-consuming :D

'Till next time...
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Re: Lonestar's RC10 OIN - turned B1M Racing chronicles (Race #2 on P.5)

Post by XLR8 »

Reading your post just reminded me of a question I've been meaning ask; why not just use the provided grub screw with Loctite to secure the CVA pin? Then, add the included retainer ring for added insurance (like belt and suspenders). Securing the pin via shrink wrap alone is just asking for trouble IMHO (like fixing a flat tire with bubblegum). Unless, I'm totally missing something here which is entirely possible. :oops: :D
Doug

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Re: Lonestar's RC10 OIN - turned B1M Racing chronicles (Race #2 on P.5)

Post by Lonestar »

XLR8 wrote: Thu Feb 15, 2018 9:49 am Reading your post just reminded me of a question I've been meaning ask; why not just use the provided grub screw with Loctite to secure the CVA pin? Then, add the included retainer ring for added insurance (like belt and suspenders). Securing the pin via shrink wrap alone is just asking for trouble IMHO (like fixing a flat tire with bubblegum). Unless, I'm totally missing something here which is entirely possible. :oops: :D
Good comment and cannot agree more with you! That's why I am using the grub screw already - and it is loctited. And, yes, I've degreased the snot out of the the whole thing... still the pin flew off both races, and even went half-way through the shring wrap last time :shock:

I think the issue is that the grub screw is a 4/40 instead of an M3 thread - less grabby thread on that short a length. Additionnally, the head is a tiny dinky SAE size (what is it, 1/32 or something) that prevents you from tightening it like you normally would by fear of stripping the thread...

Hopefully the grub screw AND a retainer clip will work this time :mrgreen:
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Re: Lonestar's RC10 OIN - turned B1M Racing chronicles (Race #2 on P.5)

Post by XLR8 »

Wow, okay. Well, hmmmm. I'd thought, under those circumstances, that pin was there to stay. If the grub screw won't hold the pin, I fear that flimsy retainer band might not hold it either. What's next, break out the welder??
I wonder if the hole the pin passes through might be a little oversize and this is allowing the pin to work itself loose?
Doug

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Re: Lonestar's RC10 OIN - turned B1M Racing chronicles (Race #2 on P.5)

Post by DaveM »

I have had that problem before, I found the grub screw was tightening up but wasn't actually going in far enough to

grab the pin.

Now I check by just having the cylinder thing and screwing in the grub screw, looking through the hole, the grub screw

should cover half the hole.

Cheers, Dave. :)

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Re: Lonestar's RC10 OIN - turned B1M Racing chronicles (Race #2 on P.5)

Post by Lonestar »

DaveM wrote: Thu Feb 15, 2018 4:21 pm I have had that problem before, I found the grub screw was tightening up but wasn't actually going in far enough in to

grab the pin.

Now I check by just having the cylinder thing and screwing in the grub screw, looking through the hole, the grub screw

should cover half the hole.

Cheers, Dave. :)
could be partially it - the pin would likely have flown off earlier in the day though... it still took it about a full raceday to work itself out... probably more a vibration thing.
Perf Shrink.jpg
Next time I need to grind a flat spot on it where the grub screw touches it. For now, this'll do... (I think)
Posilock.jpg
And, back on the car...

RebuiltUJ.jpg
I'm using plastic shock stands now, too... while the STRC ones are back on the traxxas shelfer.
PlasticShockStands.jpg
BlueStandsBacktoTRX.jpg
And the car reassembled with a proper 8.5T race mill now. This one feels sooo different in static that the throttle feel should be a totally different one on the track - not necesssarily a good thing. We shall see.
New mill.jpg
Still a few things to do but we're close to completion.

I'm debating whether to cut the body and install those B5 wing mounts I bought for this car, or to leave it with the old-school wing tubes. A naked rear body looks good when there's a transmission to show off! Here there's just a weird blank, open space at the back... Still not quite decided yet as a proper wing and mounts would make it an easier car to wrench on (and marshall... I'm always freaked out when the marshalls take an wing-tubed RC10 by the wing...)

@mk-Zero Brian, one more thing. On the left side, the screw that mounts the bulkhead to the chassis, right next to the spur, is spontaneously working itself out. I use a loctited lo-profile nut as recommended, but I think that, given the amount of stress in this area, this is not enough. Either thespur needs to be spaced further inin to use a proper-sized screw/nut, or the screw/nut asssembly needs to be swapped (nut out), or something else. Just feedback :)
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Re: Lonestar's RC10 OIN - turned B1M Racing chronicles (Race #2 on P.5)

Post by Lonestar »

Last update before raceday saturday - which will be the car's racing career swan song :cry:

NOS fluo yellow nuts received - thanks Mr. YouKnowWhoYouAre ;)
Finished.jpg
RPM world shock tower pre-drilled for custom shock mounting points (yeah I know... sacrilege... I don't care anymore, the whole car is blasphemy anyway :lol: )
Marked for drill.jpg
And drilled + tapped M3 so I can get some support from something else than then dinky M3 locknut in the back of the tower that allows for quick changes (rather than the original sandwich construction). I do this on all my racecars if they don't have the lunsford/xray quick mount systems.
Drilled.jpg
I then rebuilt the shocks, and changed rear pistons from 1.7's to 1.6's so I can get a bit more pack with still some about acceptable static hydro. I'm now on 1.6's-32.5 F & R. We shall see. The (B5) shocks had actually swallowed quite a bit of air, the fit of the lower plastic collar around the shaft isn't too impressive. I wonder if the B6's are better... Anyway. Damping has always been my challenge on this car from day zero, whatever the shock model I'm using...

And now with new spec shoes (schum cactus rear)
SchumacherCactus.jpg
Couple of final shots:
offbodyshot.jpg
TopView.jpg
and body is back on - ready for battle!
Body reinstalled.jpg
watch out for a race report next week :)
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