# in-line gearing questions



## joegri (Feb 13, 2008)

just tryin to figure out what brand and tooth combo to use on some scratchbuilds and landsharks.the longest straight on my trak is 14 feet. i was thinking that i could strart with an 8 tooth pinion and a 24 tooth crown then work from there.i looked at some wizard crowns that were drilled with 6 holes they looked cool but figured i,d ask here first. thanx for any info cuz i,m in the dark as far as this topic goes.


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## joegri (Feb 13, 2008)

i should have mentioned that my best t-jets have the 12 tooth pinion/cluster so do you think the same would hold true with mo teeth mo speed?


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## slotking (May 27, 2008)

with magnet inlines, 7/21 - 7/23 is pretty common.
with the short track, many would look at 7/23-7/25 for the punch & brake.

for a landshark? no clue
they will have more rolling weight to gear for


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## joegri (Feb 13, 2008)

thanx for your input slotking. i ended up ordering some 7 t and 8t pinions and some 23 and 24 t crown gears from lucky bobs so i can do some experimenting with the different combos. and i should mention that lucky bobs is a great place to shop with a ton of different parts makers at yer desire. i went with wizard this time but in the future i,d like to see how bsrt and others stack up.


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## slotking (May 27, 2008)

let use know how they work


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## alpink (Aug 22, 2010)

7 t pinions are going to allow the armature to get to high RPMs sooner/quicker and get the most out of their potential.
same goes for higher number crown gears on the axle.
if you notice that the car seems to be all out(highest RPMs possible) way before the end of the longest straight, change the crown gear to one or two less teeth.


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## partspig (Mar 12, 2003)

Finally! Some knowledge. pig


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## slotking (May 27, 2008)

al

have you tried going from a 7 to 8 tooth pinion instead?
I know it depends on the motor/torque of the car.

I did that with my inline super stock cars.
It smooth out how the car drives for me. with the 7t gear, my cars had to be almost out of the turn before I could punch it.

With the 8t gear, I could punch the car earlier in the turn and have very good top end.


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## alpink (Aug 22, 2010)

slotking, I always advise that "whatever works well for you is what is correct"!
I don't make corners very well, so my drag cars are geared totally differently.
but I still don't want to be at maximum RPM halfway down the straight. 
that means there is more speed somewhere in the gearing.
I applaud everyone who plays with their cars and tries different things.
but, only change one thing at a time so that you can decide if that change was an advantage.
I tend to agree with Bill Hall on a lot about slot car toys even though I sometimes race slot car money pits.
KISS
always interested in other folks ideas and certainly what works for them. some stuff is universal between cars that go around corners and cars that just go straight and even between scales.
basic principles about physics in laymans terms serves to go a long way toward making a great running slot car.
and whom ever calls us "slottards" is dead on. LOL


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## NTxSlotCars (May 27, 2008)




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## Bill Hall (Jan 6, 2007)

LMAO @ Al!

I've purposely been trying to stay out of the gearing discourse because there are waaaaay too many variables to ever KISS it in text.


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## clydeomite (May 5, 2004)

And then there is the tire Diameter part of the equation the so called final ratio isn't necessarily the final ratio when you factor in tire size. let me illustrate...24 tooth crown divided by 8 tooth pinion = 3.0 to 1 but that would be with a 1 inch tire so divide final ratio (3) by .440 ( tire size) and you have a 6.81 ratio....... that is when a tooth here and a tooth there can make a lot of difference.:wave:
Clyde-0-mite


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## alpink (Aug 22, 2010)

yep, tire size always comes into play, but that wasn't the question this time. LOL!
good job anyway clyde. one more parameter that makes my head hurt.
one change at a time until nirvana then.
LOL


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## SDMedanic (Apr 21, 2011)

It all comes down to the driver. Case in point the car builder put in a 7/22 gear set. I couldn't deal with it and qualified dead last in about a 20+ car field. At that point in time the builder became disinterested and I took over. I switched to a 7/25 gear set. In the race I made move up after move up and ended up third overall.


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## joegri (Feb 13, 2008)

i recieved my gear sets last week and just now(lastnite) started to install a 8 /24 gear ratio but cuz the rails on my routed trak seem a lil tall and the chassis(landshark inline )seems a lil low i,m gonna have to use some tall tires so the chassis wont bottom out!but at this moment i,d be happy just to see it get around the trak! after that i know i,m gonna have to change,em out to something different cuz of the the tire size. and sd that is an interesting story of yer experience with changing out gear combo,s thanx for that.


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## Hornet (Dec 1, 2005)

If you're using a Supertough Wizz crown,you can swap it out for a Pro Predator crown,which is smaller in diameter.
If i remember right,the Supertough is about .410" in diameter,and a Pro Pred is about .380/.390"


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## Dyno Dom (May 26, 2007)

Nice thread w/good info!! :thumbsup: My MT layout has a 19 ft. table length
with long straights and changing radius curves of 17, 23 & 29 ins. My G-jets
run a rear tire of approx. .450". Although the same ratio of 3, a gear combo
of 7/21 would give more top speed/coast than an 8/24 set.


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## slotking (May 27, 2008)

even if the gear ratio is the same
the effects can be different between a 7t and 8t pinion because the size of the crown changes which adds weight & rolling mass and related effects

but with road courses, I do not look at gear ratio the same way drag racers do.

They have to go from a dead start to top speed in X distance.

with the road course, you constantly moving, when you come out of turn you most likely at a minimum of 40% of top speed. 

I used to run 7/21 in my super stock cars. I tried 8/21 and found I could get better times because I could go in almost as deep into the turn, but the key was I could punch out earlier in turn. If i try to punch out with 7/21 in the same spot as 8/21 i de-slot.

so by going 8/21 I can punch earlier, i get more top end for long straights, and the car feels smoother.

but that fits my driving style


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## Dyno Dom (May 26, 2007)

SK, as always good points!  The 8/21 sounds to be a good option.
Early punch, good top end & smoother driving ability sure merit a try!!


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## Gareth (Mar 8, 2011)

Hi all,

I'm reviving this thread as it has some superb information in it. 

I raced an Artin F at the weekend as my Lifelikes were all sidelined with some issues. I'd done some work to set up the car for high downforce, added a fast Turbo can and used Lifelike front tyres for a nice low profile front end. Rear set up was 0.422 or 0.426" (forget which set I ran in the end) Supertires on Harden Creek 0.265 rims. A Lifelike Porsche body held in place with sticky pads was a low weight body so I went with that. 

The car was fantastic through the bends, almost too fast, but it was lacking down the straights. I used the stock Artin gear ratio of 8/22 with the stock gears but I'm wondering what you guys would recommend to up the pace?

I was thinking of swapping the crown gear to a 24 tooth but would 7/21 be faster?

I'm really happy with this car as it has turned out to be much better than expected. I hope I can extract some more performance with the ratio change. The only other tweak I would make is seeing if the car will accept Marchon shoes instead of Artin ones. The Artin design is a bit flawed to my mind.


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## slotking (May 27, 2008)

> I used the stock Artin gear ratio of 8/22 with the stock gears but I'm wondering what you guys would recommend to up the pace?
> 
> I was thinking of swapping the crown gear to a 24 tooth but would 7/21 be faster?


7/21 is faster than 7/24
7/24 has more punch/brake than 7/21

the 8/22 is faster than both of the above but with less punch & brake
if the track is open (lots of good straights) the 8/22 or 8/21 should be the way to go.

with small twisty tracks many drivers like the 7th pinion


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## Gareth (Mar 8, 2011)

Hi Mike,

Thanks for that. I didn't find the 8/22 ratio to be particularly quick. My usual Lifelike setup is much quicker in a straight line and on that Sunday, the only car I was beating down the straight was an SRT and I don't know how well that car is set up. I couldn't keep up with the Marchons and Lifelike Ts on the straight. Only in the bends.

My thinking was to go either 7/21 to increase the final ratio and give me a bit more much needed acceleration or to go 8/24 which would give the same final ratio as 7/21 but would perhaps give more driveability as you suggested in your earlier posts on this thread. 

I did a build with an Artin a year or so ago and on that one I tried 8/20. The car was absolutely gutless. The traction magnets are pretty strong so it was stuck down quite well but for the class I'm building the car for I need both high end speed and lots of downforce. 

That build put me off the Artin for a long time and also made me realise that just chucking smaller crown gears and bigger pinions at a chassis doesn't always make it quicker. At the club quite a few of us went that route with the SG+ chassis and most have reverted back to 7/25 now. 

This time, as I didn't have a 24 tooth crown in stock, I went with 7/21. I couldn't use the Turbo pinion I wanted to use as it isn't long enough but the Marchon pinion is similar in design to the Artin one so I used that and coupled it with a Pro predator crown gear. 

I had a number of significant issues getting the mesh sorted and dialing out the slop, primarily because of having to thread everything through the chassis sides but I eventually managed to suss it all out.

It is Nascar at Worthing HO tonight but I will give the chassis a test run to see if it is any quicker. 

Standard Artin Chassis



New modified gear set up



And yes that is an SG+ motor bearing nestling next to the crown and the white shaft is a stock Artin shaft which I cut the crown off of. Hence the lumpy finish by the chassis rail. I'll clean that up if the car is quick.


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## slotking (May 27, 2008)

> Thanks for that. I didn't find the 8/22 ratio to be particularly quick. My usual Lifelike setup is much quicker in a straight line and on that Sunday, the only car I was beating down the straight was an SRT and I don't know how well that car is set up. I couldn't keep up with the Marchons and Lifelike Ts on the straight. Only in the bends.


yeah, sometime the motor/mags do not provide the torque for the bigger pinion.

normally for example, on a real long straight, the 7/21 should come out of the hole faster, but at the end of the straight the 8/21 should be there 1st.

Driving the 8 is a little different, you should be able to punch it a hair sooner in a turn, but something you have to adjust to.

The 7T pinion provide less work for the arm and help better if the motor are not very strong.

but either way, you have make sure the 7 or 8 has good mesh with the crown. it make a big difference


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## Gareth (Mar 8, 2011)

I think you are right with the traction magnets affecting things. The guy who won on Sunday with a Marchon said he had to change his gear ratio when he swapped the chassis due to the chassis all being slightly different from each other. I can attest to that as I set up a Marchon with the ultimate set up bits and it is rubbish! 

Really looking forward to trying the car out in a couple of hours time. 

Thanks again for your comments and advice Mike. You seem to be the only one interested in this project on either board!

Cheers

Gareth


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## shocker36 (Jul 5, 2008)

Looks like a lot of moving mass on the rear axel


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## Hornet (Dec 1, 2005)

shocker36 said:


> Looks like a lot of moving mass on the rear axel


Ditto,you gotta get a lighter axle set-up.

For one throw the un-used spacer on the drivers side axle away,it's just added weight,and isn't necessary.
And find something lighter then the SG motor bearing as your drive side spacer,hollow piece of plastic from the spray tube on a WD-40 can might work instead.
That axle assembly will slow your acceleration way down,especially if you're using the taller ratio's suggested above.
You can also drill lightening holes in your hubs and crown gear to help with acceleration.
The hubs can be lightened by drilling the tire surface and also the back side


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## Gareth (Mar 8, 2011)

Hi Guys,

Thanks for your comments. I agree I need to lose the bushing. It is too much weight but it was getting late and it was the right size for the space.

I have to say I disagree on removing the sleeve from the long side. I've spent the last couple of years developing Lifelike T chassis for racing and my first setups only spaced on the rear of the crown to stop slop. Unfortunately the car corners so fast that the lateral load bends the armature and eats the gears. The last WHO Mod round in January ended in retirement as the car destroyed pinion, crown and pulled the axle out of the chassis. All without crashing which shows just how violent the forces going through the car are. 

Since I don't have an unlimited budget for gears (and indeed chassis), I've decided that all of my high downforce race cars will be fully sleeved on the rear axle. Yes it might give up a little bit in terms of weight but you don't score good points if you don't finish the race!

Here is a photo of my Lifelike sleeved effort. I used a Turbo gear saver and shims. I really like the idea of WD40 tube though. I will try that next. 



Cheers

Gareth


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## slotking (May 27, 2008)

> I have to say I disagree on removing the sleeve from the long side. I've spent the last couple of years developing Lifelike T chassis for racing and my first setups only spaced on the rear of the crown to stop slop


2 options
1>what I did was to use a small piece of tubing which is smaller and lighter
2>even lighter is to space behind the hub. that way the tire acts as the stop

either way use you should use 2 pieces or more
so when it slams into the chassis you have less friction


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## Hornet (Dec 1, 2005)

Gareth,look into getting yourself some locking spacers/shims for your axle.
They're alot lighter then your current spacer set-up,and will free up some horsepower.
I know getting spacers might not be easy for,but if i remember right you guys deal with Lucky Bob once in awhile,and i think he carries the locking spacers.
Wizzard also carries them.
For now though,i'd look into something a little smaller in diameter and lighter.
That big diameter spacer puts alot of drag on things,as the weight of the spacer is along ways off the axle centerline,and it turns it into a big rotating mass that you have to accelerate/de-accelerate


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## slotking (May 27, 2008)

spacers work well
that what i do behind the hub & gear

I also really like the scale engineering gear boss
It keeps the gear lash just right.
using it and you do not have to worry about getting the spacers on the right side of the chassis when you in a hurry.


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## Bill Hall (Jan 6, 2007)

*Sumting Wong with the Clarence?*

Is it just me, the camera; or does Gareth's LL set up look preloaded? :freak:

The axle rails appear to be splayed out of square. Looks like the shoulder side shim has the crown gear mashed hard against the pinion. Note how the pinion teeth are trying to get away (folding out from the mesh point)? X is too close to Y 

While I completely agree that excessive thrust has to be limited in some fashion; fundamentals like keeping the gear mesh perpendicular, and observing running clearances should be first. Older plastic chassis have quite a bit of flex in them and maybe some wear as well. It is quite easy to force preload into your builds. Sometimes we just have to accept that cross matching old plastic gears doesnt always work out for the best. My reject pile is legendary! Next next next next.....LOL. 

I'd loosen that puppy up until there was proper clearance, and reset the pinion. The crown bite looks to be just short of the sweet spot. :thumbsup:

Just spit balling, I love the use of everyday items used to get cars down the track! :wave:


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## Gareth (Mar 8, 2011)

*That's What I'm Talking About!*

Ah you see this is what is makes forums and sharing builds so fantastic. I am learning a lot here. 

Light and even tubing is definitely something I want to look into. Indeed it was the original recommendation but I've not got the tube yet.

Hornet, the locking spacers sound intriguing and if they do what I think they do, they could be something worth trying. Especially on the Artin where you have to thread everything through the chassis rails. Thanks for the tip on these, I'll order a few pairs to try.

Bill, well observed and I think I might have to do a macro shot of all of my future race builds as it will help show up any issues such as you have identified. I've not heard the term pre-loaded before in terms of gears but I think I can see what you mean.

In terms of the chassis rails, that chassis has done some pretty hardcore racing and is actually pretty wrecked. I can see the bowing you mention in the photo but you can't see it with the naked eye. The rear bulkhead is seriously bowed as well which seems to have affected all three of my good race cars. The motors are terminal as well! Didn't think it would be possible to drive these things to death like that but they really do have a terminal lifespan when abused like this. 

So to recap, for the Lifelike I need new chassis, new motors and thin tubing to sleeve the axles in a lightweight, even weight distribution way to reduce spinning mass and large weights which could affect the cornering. Phew that sentence said weight a lot!!

The Artin I think the locking spacers could be the optimum way to go. I've got it on 7/21 at the moment. Didn't have much of a chance to run it last night sadly as we were very busy with 24 racers on the grid.

Cheers

Gareth

EDIT: Thinking about it some more, I think the armature on that motor might be lightly bent. It certainly doesn't run as quick as it used to before that big January wreck and the LL arm is very thin.

Oh and I'm off to Thailand tomorrow for a couple of weeks so won't be around but please keep the suggestions coming. I really appreciate all the recommendations and tips from you guys.


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