# advice on making 4 gears run smooth and freee



## racer8nut (Mar 25, 2010)

Hey all,
I have recently bought some AW 4 gear chassis and most of them are tight. I have tuned many x-traction cars with great success and love tuning them. But, these 4 gears are testing my slot car tuning knowledge(little boogers). Here is what I've done.
*Stripped the whole car.
*smoothed the gears
* check for the armature spin without components in the car(brushes, magnets etc...)
*Checked rear gear mesh. make sure it runs free
*Loosened gear clamp
*lossened rear screw-a little
* Adjusted tabs on the bottom looking for power or lack thereof.
* Polished armature bottom
Any advice would be great or is it time for the sledge-o-matic:jest:
Thanks for the help:thumbsup:


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## dlw (Aug 17, 1999)

While you have the car stripped, check for untrue rims and bent axles.


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## Boosted-Z71 (Nov 26, 2007)

Go through the car front to back, adding components as you go and eliminate any excess friction or dragging, Gear mesh, axle or shaft bind etc, look for anything out of round or with any wobble & correct that. You may have to slightly enlarge some shaft or axle holes, by drilling or lapping. Everything must roll smooth & free with no noticeable drag spots. Also dont overlook the electrical, many cars have loose rivets in shoe hangers that provide poor electircal connection that will kill the pancake style chassis. Another problem is with magnets that are very loose and can hit the arm, you can shim them with paper to tighten them up. After that its time to switch up magnet & arm combos looking for that sweet combo, and then start adjusting com brush tension for max performance. 

OH MY GOSH, I have to stop, as this almost sounds like Fray car tuning, and we all know how involved that gets. 

Boosted


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## Bill Hall (Jan 6, 2007)

As Dave pointed out, the weeble effect is a big issue. If you've been to the circus and seen the clown car driving around with the off center hubs, you'll have the mental picture. 

ONCE I'VE OHMED THE ARM, (first things first) I like to work my way backwards from the axle. Dump all the stuffing out and carefully inspect the gear teeth; then methodically add each component back in one at a time... all the while rolling the rear tires across my fingers. Feel for any glitches and WATCH how the gears are riding on the plate.

When I get to the last idler, I leave the comm pit empty and check the whole enchilada as a unit. Then add the brushes and feel for any snaggles, then remove them. Then add the magnets and click the arm through a few rotations.

Obviously if everything checks out, your probably looking at a secondary tuning issue. I have often found that the four gear design can be a bit sensitive to pick up shoe adjustment. Sometimes the slightest correction can make the difference between a dog and a demon.


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## joegri (Feb 13, 2008)

*i gave up*

thanx for posing this question. this past winter i spent a whole evening tryin to make a 4gear go. seemed like hours went by and tried many tips n triks. then it hit me. "i can barley make 3 gears go good" so i dismantled it and put all my 4 gear stuff in a box and hid them till next time i wanna try. seems i,m always behind the curve and i read all the hubbub bout the 4 gear but i have a hard time gettin into em.


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## tasman (Feb 17, 2007)

Racer8nut,

I have experienced the same problems and been through pretty much everything you tried with the same results as you. I have posted the same question in other sections and gotten pretty much the same advice. 

I have seen many posts that the 4 Gears are really fast, yet all of mine act like yours and tuning doesn't seem to get me much improvement.

I still think it comes down to the 2 removable idler gears. I have "lapped" the gears repeatedly but there still seems to be a "tighness" to the drive train once they are put in place. 

I don't know what else to do. I do not have any old 4-gears and have no other gears than the ones that came in the cars, so I can't even try replacing them with old stuff.

Help!


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## LDThomas (Nov 30, 1999)

If all seams well until the two idler gears are installed, could be problem be that the brass clamp is dragging on the idler? Or is the brass clamp causing the arm to bind in the chassis?


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## Boosted-Z71 (Nov 26, 2007)

Guys if you will and have the means to check the idler gears you will find that many of them are not round, neither the brass or plastic. If you have the spare parts search for the best round gear & try that to see if the speed picks up, these little pancake cars are monsters when you try to tweak everything out of them. Any tightness, out of round, or excess slop will kill your speed, unfortunately the electrical side is just as picky on spring pressure for shoes & brushes.

Boosted


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## tasman (Feb 17, 2007)

LDThomas said:


> If all seams well until the two idler gears are installed, could be problem be that the brass clamp is dragging on the idler? Or is the brass clamp causing the arm to bind in the chassis?


I checked that on all of mine and adjusted the clamps on those that looked like they might cause binding - it didn't help much. I did catch that exact problem on a couple of recent X-tractions and adjusting the clamp made a noticable difference.


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## TGM2054 (May 14, 2011)

Make sure that the screw that holds the back of the gear plate isn't over tightened. That can put a well tuned car into the dog catagory.


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## dlw (Aug 17, 1999)

I'm suggesting this on the basis you have a dremel tool (preferrably battery powered) and some extra front rims.

What you can do is to first remove the comm magnets, brushes and springs. Reassemble (minus the noted above) and place tires on the rear rims. Then chuck-up a front rim onto your dremel and place a tire on it. Use the dremel to lap your gears (at slow speed at first). The more you lap them, you'll hear the gears slowly improve mesh. This may sound weird, but do some lapping in both directions, as this will improve the mesh. after this lapping those gears should be free enough to hand-spin the rear wheels with little or no resistance. 

The put the magnets, brushes and springs back in the car and it should run much better.


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## kiwidave (Jul 20, 2009)

Also watch for a little plastic "Burr" on the AW axle crown gear. I've had to file a couple to stop binding from the gear against the inside of the chassis.


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## slotcarman12078 (Oct 3, 2008)

I had a blob on the outer edge of a crown gear that was causing binding too, though that was on a T jet..


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## Bill Hall (Jan 6, 2007)

D'oh!

I wrote all that blather and forgot the most important part. Thankfully Dave came through with lapping!

I have yet to meet a vintage or modern four-gear that didnt benefit HUGELY from lapping.


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## dlw (Aug 17, 1999)

How are they running now, Racer8nut?


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## racer8nut (Mar 25, 2010)

*Thanks for all the advice*

Hi all,
Thank you for all the great advice. Unfortunatley, I have not been back to work table to tune on these little buggers. I went on Vacay and came back to a house full of water. The line behind the frig busted and sent water all over the house. Had to rip up laminate florring, tear baseboards etc.... It also wicked up the drywall, but we have a restoration crew drying eveything out, So... my slot car tuning and fun is taking a backseat to insurance claims and clean-up. Sux big time... but we have our health, family and a roof over our heads to we get back to normal. When I do...my little one a nd I are going to do some serious playing:wave:


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## 1976Cordoba (Sep 20, 2000)

racer8nut said:


> . . . I went on Vacay and came back to a house full of water. The line behind the frig busted and sent water all over the house. Had to rip up laminate florring, tear baseboards etc.... It also wicked up the drywall . . .


 
:freak: D a n g - sorry to hear that man - That SUCKS!


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## racer8nut (Mar 25, 2010)

Thanks...we have a recovery crew drying out the place and hope to get things rollin as soon as we get te go ahead. Meanwhile, I am going to head to my local track here in daytona Beach with little one and do some slot racing:wave:


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## drumz2005 (Jul 31, 2012)

*lapping gears on 4 gear chassis*

Hi all,I was curious as to what you use to lap plastic gears with ?


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## Bill Hall (Jan 6, 2007)

drumz2005 said:


> Hi all,I was curious as to what you use to lap plastic gears with ?


Ultra Brite tooth paste...:thumbsup:


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## dlw (Aug 17, 1999)

I am a little wary with using something to lap plastic gears since it don't take much to grind down plastic, so I just had a nice break-in period, running a car for a few minutes off a battery, or powered track at lower voltage, then reversing polarity to run in other direction.


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## Bill Hall (Jan 6, 2007)

*Try it, you'll like it!*



dlw said:


> I am a little wary with using something to lap plastic gears since it don't take much to grind down plastic, so I just had a nice break-in period, running a car for a few minutes off a battery, or powered track at lower voltage, then reversing polarity to run in other direction.


No worries! Ultra brite is 100% guaranteed. Over time I modifed the process and now include oil to help keep the slurry viscous. It'll dry up after a bit so ya just reload on top of whats already there and let it spooge around.

The worst case scenario was:

Over the years I'd acquired many lots of parts. Eventually you get them all sorted out. After carefully selecting all the parts, with special emphasis on gear inspection, then assembling the four gear stuff (a dozen er so); I was plagued by sticky, dragging gear plates, undue friction/heat, vibration, and gears walking up and down and all around. There's also that freaky harmonic thing when plastic gears spazz out.

I attributed the problem to the scrambled mismatched gears.

So I tried the lighter deal where ya lightly flambe' the gears...not a precision or truly controllable technique.

....then I tried the buffing with the wire brush deal... doesnt do the gear centers, posts, or thrust surfaces.

....then I remembered the old Heloise Hints thing about using tooth paste for polishing plastic....ding ding ding I knew I had a winner. 

It works great, and the butt end of a tube has lasted years.

I just lap as usual. I do the rear axle bores, the crown and pinion, and the main gear plate all at the same time. I like to take the time and reverse direction so decel is silky smooth too. Just watch yer heat and ALWAYS finger roll the wheels after reloading the slurry.... so you dont dead start the armature. Keep going until the armature pipes all the way up and the gear set calms down. 

The results were fantastic....unless of course you've missed some glaring deformity or damage. I now use the process on all plastic geared designs including in-lines without incident.

The IMPORTANT thing to note is that you really wont see the full benefit until you clean the whole mess up, re-oil, and run it in. :thumbsup:


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## ruralradio (Mar 11, 2011)

*Do it!*

Great tip, Bill. I've always used plain old Colgate mixed with a bit of ATF to thin it to a slurry, even on 3 gear cars with brass idlers. As you noted, cleaning the mess up and lubing afterword is paramount. I may be odd (!), but I never use oil anywhere but the brass axle bushings on my retro pan cars (or back in the day when they weren't retro), I've always used plain old lithium grease, aka Lubri-Plate. I'm not drag racing, but road racing with 3 or 4 ohm pancake arms. Had a problem with oil collecting in the brush cups, not a good thing. Probably caused by over exuberant oiling, but it works for me. The old, thick, Aurora "red" oil worked well, too, when you could find it.


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## Bill Hall (Jan 6, 2007)

ruralradio said:


> Great tip, Bill. I've always used plain old Colgate mixed with a bit of ATF to thin it to a slurry, even on 3 gear cars with brass idlers. As you noted, cleaning the mess up and lubing afterword is paramount. I may be odd (!), but I never use oil anywhere but the brass axle bushings on my retro pan cars (or back in the day when they weren't retro), I've always used plain old lithium grease, aka Lubri-Plate. I'm not drag racing, but road racing with 3 or 4 ohm pancake arms. Had a problem with oil collecting in the brush cups, not a good thing. Probably caused by over exuberant oiling, but it works for me. The old, thick, Aurora "red" oil worked well, too, when you could find it.


I rekon it's a subliminal thing from adolescense. While Colgate was prattling on about the marvelous benefits of MFP, and Crest was serving up gap toothed kiddies with cavity reduced report cards; the Ultra-brite girl just gave me that knowing wink and a smile that went "ding"...

Remember?

We only saw her smile for the first season.

Then we saw she was SMOKEN'! 

LMAO! The silly things you remember when your lapping gears. 

I also use some black moly assembly goo that I've had good luck with. Like a good dog, it hangs around and doesnt wander.


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## ruralradio (Mar 11, 2011)

Bill Hall said:


> Then we saw she was SMOKEN'!


OMG, I'm 13 again.....


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## Ralphthe3rd (Feb 24, 2011)

Bill Hall, it's great to see you back again(from your self imposed Exile?), and doling out helpful advice and tips :thumbsup: We missed you, and I for one was going into serious withdrawl


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