# Gear Boss or Spacers?? Gear tuning?? Help!



## [email protected] (Jan 25, 2007)

My biggest G3 problem is my rear end (so to speak) i seem to be chewing gears at a prodigous rate.It also causes heat. Any tips on spacing and alignment of axle, gears, gears boss and spacers for smooth fast running?? I know the breaking in with simichrome. routine. My issue is more alignment and spacing. Thanks in advance for your sage wisdom. mj


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## Hornet (Dec 1, 2005)

Who's gears,if they're stock,run them with about 2 or 3 thous clearance.
Add a couple extra sapacers to your axles when you slide the tires on,the extra spacers can ride outside the chassis wall till you need to move them over to re-shim the gears.
WizzardHO has some nice brass spacers that measure roughly 2 to 3 thous in thickness,if you add 2 or 3 of these as extra's,you won't have to pull a wheel off to stay on top of the spacing


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## [email protected] (Jan 25, 2007)

BSRT gears 7T pinion and 23T crown gears


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## Hornet (Dec 1, 2005)

You can run BSRT's gears a bit looser,and they'll live pretty good.
On them,i run roughly 3 to 4 thous clearance,without a gear boss :thumbsup:


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## [email protected] (Jan 25, 2007)

Thanks, I'm finding its a fine line. if they are too loose i lose power....... if they are too tight i lose power and heat up. I have found sometimes they run better with the boss sometimes the spacers. So much to learn. mj


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## TurnNBurn (Mar 13, 2007)

Citylights17, what Hornet said plus... my 2 cents... You didn't say what race class of car but here goes...

On SS type car and a soft chassis (Tyco, soft G3's, soft Storms, etc), I will usually do both, boss and spacers as I want to maintain the gear alignment when the chassis is flexing.

On a SS type car with hard chassis (SG+, stiff Storm, etc), usually just spacers.

Also, when using BSRT gears (I heard this from I don't know where, way back when), make sure you use the same material for both pinion and crown. Don't know if this is true or not but I've always done it and never had a gear chewage problems.

If I'm wrong on any of this, I'm sure somebody will let me know.

TnB


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## [email protected] (Jan 25, 2007)

TurnNBurn said:


> Citylights17, what Hornet said plus... my 2 cents... You didn't say what race class of car but here goes...
> 
> Thanks TnB I'm runnung poly-mod, i haven/t tried the boss and spacers, but it sounds worth a try. My gears are the same material poly pinion and crown. Sometimes i get it right but i need consistency so i'm looking for a clue. mj
> oh and i use a medium or stiff G3 chassis


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## Hornet (Dec 1, 2005)

Are you running bearings.
If not,get them,they'll help your gears to live longer in a poly/mod,if you only want to run one bearing,do it at the back.
Personally i never run a gear saver,don't really feel they're needed,and the extra rotating weight will add heat to the car,but that's only my personal opinion :wave: 
Turn n Burn,man haven't seen you around for awhile,how's it going .
BTW:take his advice too:thumbsup: 
Rick


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## Montoya1 (May 14, 2004)

I have always wondered why nobody does and axle with cir-clips. Too much friction? Too weak? Too fiddly?


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## [email protected] (Jan 25, 2007)

Hornet said:


> Are you running bearings.


yes hornet i'm running a bsrt bearing in the rear and the new bsrt bushing in the front. I'm gonna work on this car today and see what i can do. montoya how does that doojigger work?? between the chassis and wheel or inside? Does it work better than spacers?


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## Montoya1 (May 14, 2004)

We used to use them a lot in RC racing. You would need four grooves in the axle, running all the way around and then the c-clip pops on as it is slighly sprung. I guess it would be overly complex but in theory would be better in spacers.


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## [email protected] (Jan 25, 2007)

another question where do you guys run your crown in relation to your pinion front to rear?? does it matter? Thanks for the answers so far. i'm toying with one of my cars now. Lets see............ mj


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## Hornet (Dec 1, 2005)

I run the pinion as deep into the crown as i can,theorizing that's where the pinion is strongest,not sure it's right though :wave: .
Deane,to lock the rearend into place,i quite often use 4 of Wizz's little AA12 spacers,they're a press fit onto a drillblank axle,accomplish's close to what you have with the "C" clips.
I think strength might be the only reason somebody hasn't developed a "C" clip axle for use in HO,the weak point would be the machined in grooves,but it is a very good idea,sure would make things easier to work with :thumbsup: 
I use one on either side of the gear and one on the inside of each tire,it takes quite a wall shot to ever move them even on a .0595 drillblank,usually you're looking at replacing something else if you've hit the wall hard enough to shift things on the locked in axle.
BTW:CL,what are you using for axles


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## Montoya1 (May 14, 2004)

Years ago when my chassis was all in my head, it had a fatter axle with a flanged bearing on the outside and a circlip on the inside. Basically what 1/12th RC circuit racers had, only a lot smaller. Of course nowadays I am more aware of everything being a trade off. Extra mass, rotating or otherwise, is a double-edge sword.


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## Hornet (Dec 1, 2005)

Yea weight is a big factor,i wonder if it could be made hollow Deane.
I've thought a square axle with machined in grooves where it rides in the chassis might also be viable,but i'm not sure how it'd be strength wise and weight wise,it would have to start out a little bigger so that you could machine the grooves to somewhere around .059".If it could be made hollow it might not be bad weight wise either.
I hate drillblanks,but strength wise and cost wise,i haven't found much that beats them ,they're a pain in the butt to work with though


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## [email protected] (Jan 25, 2007)

OK figure this.......... I bought a BSRT 906 ceram/poly to see if i could do some reverse engineering. 37 spinner, 24crown, .438 rear, .345 front. Replaced the front for an indy, switched out the guide for a longer one. Popped on a lexan bod its sweet not super fast btu fast and handles really nice.... i can go much deeper in the corners and faster out.
But the point is I took the rear end from the car I am building titanium axel 23t crown .454 tires and put it on and my temp shot up about 15 degrees in a few of laps. it could be the mesh or it could be the ratio any feedback? It seemed to run fast and smooth otherwise. thanks in advance. mj


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## Hornet (Dec 1, 2005)

Okay don't yell at me,but how was your driving. :thumbsup: 
If the gear and tire change caused you to be a little less smooth,that'll affect the cars temp more then anything.At 454 you should be plenty high enough off the rails,and 1 tooth crown jump shouldn't make for that big a temp differance 
Alot of guys don't realise how much their driving will affect the cars temp,especially in a Mod or R/O car.It's not uncommon to see a 15 degree differance in temp on the higher end mag cars,if you're driving isn't smooth.
The higher end mag cars require you to smooth out your driving style, :wave: :wave:


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## [email protected] (Jan 25, 2007)

Hornet said:


> The higher end mag cars require you to smooth out your driving style.


OK, I'm cool with that......I'm a newbie trying to learn so i'm open. as you said that isn't something that i had any idea about. please explain what you mean by smooth and how that affects temp. I'd be much obliged. i don't think there was any change in my driving approach though. With the 24T i can really "slam it" and it won't go past 130F usually 119F or so. But the other rear end the temp jumped to 140F very quickly and was normal again with the stock rear. hmmmmmmmm. But just let me know what i should be attempting to do. much thanks, mj


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## Hornet (Dec 1, 2005)

Do you have a timer on your track,and a good slot car buddy.
Usually the cars temp is a good sign of how you're driving is.
Sometimes it helps if you have a buddy who's sorted tuned into slot cars to help you.
What i try to do is drive each lap virtually identical (right on the edge,lol),to do this you have to really smooth out your trigger action,and try to avoid inconsitent pulls on the trigger.
One thing that helps me,is i try to always place my trigger finger on the same exact spot,and hold the controller the same way each time,usually with both hands.
If you can get a buddy to watch you drive,sometimes he'll be able to catch things that you might be missing,and he can watch the timer lap by lap for you.The more consistent the times the better usually
You can test this by proposely driving the car with a very rough action on the trigger ,and then try driving it with a smoother trigger action,usually you'll see quite a differance in temp,and it's not uncommon to see a 15 degree differance.
So if nothing's binding and the gear mesh is good on both rearends,see if one axle assembly maybe makes the car slightly harder to drive, causing you to work the trigger more,sometimes a one tooth crown gear change can cause the car to be a touch harder to drive.
Hopefully this babble sorta makes sense


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## [email protected] (Jan 25, 2007)

Hornet said:


> Hopefully this babble sorta makes sense


Thanks H, It is clear and makes sense. I have a timer (no split times though) and I will work on this. i found my mechanical issue. i had ripped the car down twice and on the third time i decided to work on the bearing (last resort) I knew something was wrong somewhere. I soaked the bearings in laquer thinner, lubed and replaced it put on a fresh pinion and lo and behold....... down went my temp up (way up) went my speed. It looked clean but some gunk was in there. Shes much faster than the 906 now just have to dial in the handling..... and my driving ! LOL thanks for the tips they will help. Speaking of holding the controller I am the only person i know who uses their thumb on the trigger. Always have always will. I can't do it any other way. So i'll put my thumb in the same spot each time. mj


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## Hornet (Dec 1, 2005)

Thumb,yup that is differant,but if it works for you,don't change :thumbsup: 
Ah,you used red loctite on the pinion  .
You have to be careful with it,cause it will migrate into the bearing at times.
I've got a buddy who has this happen to him quite often,he puts his loctite on the shaft,me i usually just put a dab of the red stuff inside the pinion neck,using a small toothpick,and i usually don't havea problem,but my buddy who puts it on the shaft seems to be always fighting a locked up bearing,i've been trying to convert him to just putting it in the pinion neck,but he's an older fella,and a bit set in his ways :wave:


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## [email protected] (Jan 25, 2007)

I use the locktite 380 but you're right on all other counts. I'll take that tip too. mj


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