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Retro tuning tips & tricks


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#1 Noose

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Posted 27 August 2013 - 01:11 PM

We also have a section on the website. As I can gets guys to write articles we will post them. Some are already there of course.

The first tip every racer should follow is to maximize what you are allowed to do. For example, I know Matt and I have told many racers they should set their cars with the wheels at the maximum width allowed. You'd be surprised at how may cars I see in tech where they aren't.

 

Another are the clearances. How many guys every check theirs after putting a new set of fronts on?

Use the handy dandy quick tech list and ask yourself if you met all of those at the max allowed.


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#2 gascarnut

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Posted 27 August 2013 - 01:39 PM

For example, I know Matt and I have told many racers they should set their cars with the wheels at the maximum width allowed. You'd be surprised at how may cars I see in tech where they aren't.

 

Sometimes there's a good reason to be narrow, at the rear at least. In front, I agree - all the way to the limit, but at the back it depends on what the car is doing.


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#3 Gator Bob

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Posted 27 August 2013 - 01:40 PM

Here is one from the chassis god himself.

 

"Check/reset your front axle (clearance) after every race." "That's why I never wire wrap the uprights.."

 

Now... will he tell me any more tricks... LOL.


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#4 gascarnut

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Posted 27 August 2013 - 01:42 PM

Here is one from the chassis god himself.

 

"Check / reset your front axle (clearance) after every race." "That's why I never wire wrap the uprights.."

 

Now ... will he tell me anymore tricks ... LOL

 

Wire-wrapped axles can be adjusted.

 

It's all in how you wrap them...


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#5 Gator Bob

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Posted 27 August 2013 - 01:45 PM

Dennis, do you mean like to only one upright post or the tension of the wrap... other? 


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#6 gascarnut

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Posted 27 August 2013 - 02:28 PM

Bob, this is the best shot I could find to explain:
 
DeMott Z rail 004.jpg
 
The wire wraps around the uprights and goes over and under the axle. If you heat up the whole area, then the wire slides along the uprights to adjust the height. Good amounts of heat, and lots of flux.
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#7 gascarnut

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Posted 27 August 2013 - 04:50 PM

This one applies especially when talking about motors, especially if you like to use screws to hold the motor into the frame:

 

Are you sure that both the motor bracket AND the motor end plate are flat and square?

 

There's not much you can do legally if the motor is out of square, except solder it in so that you don't rely on the screws, but if the bracket is not flat you need to do something. Find a flat file about 1/8" narrower than the motor bracket face. You want to use the biggest, thickest, stiffest, flattest file you can find that will fit. Then file the motor mounting surface of the bracket slowly, making sure the whole of the suirface is touching the file and moving just a little back and forth keeping the file in contact with the whole surface. You will see whether the face is flat very quickly by the file marks on the surface. File it all until you have file marks across the whole surface where the motor will mount, and especially all the way round the holes where the screws go. This all could be done before the bracket is soldered into the frame, but in my experience it works better if you can do it afterwards, as then the bracket is already in its final position and is not going to move much.

 

Now when you screw in a motor, put the screws in loosely at first. Hook the motor up to a power supply at low voltage (3 volts or so) and look at the current draw. Then watch what happens to the current draw as you tighten the screws, and listen to the sound of the motor. If anything is out of flat, you will find the revs go down and the current draw goes up. If that's the case, you need to fix something. Either the bracket is still not fully flat, or the face of the motor is not flat. More filing might help, and check that the solder joint that holds the ball bearing into a PD motor is not fouling on the bracket hole. I like to put a big chamfer on the center hole of the bracket to avoid this.

 

I had one FK motor so bad that when the screws were tightened the armature would not turn. Without modifying anything, the only way to use it was to solder it in.

 

This is also one explanation of why a motor that runs well in one car may not run so well in another.

 

As most have been saying, "the difference is in the details".


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#8 Gator Bob

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Posted 27 August 2013 - 05:02 PM

Exactly!
 
And... with the Pro Slot motors the 'ears' must be checked for square also. I only screw motors in and they can bend in a wreck... much more so with the older 'thin' can.

Another thing is with the 4002B-B the hole in the motor bracket must be chamfered or opened up to fit properly. Do this step before mounting the bracket, it's a pain to chamfer after assembly.
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#9 Bernie

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Posted 27 August 2013 - 05:06 PM

Dennis,

You rule. Never thought about the flatness of the motor bracket. Makes a whole lot of sense. I will be checking ALL my cars now! :good:
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#10 Cheater

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Posted 27 August 2013 - 05:16 PM

We used to do something kind of similar with Flexi chassis.

Once the car was assembled and the motor, axle, gears, and tires were in place, you'd run the car on a power supply at a pretty decent voltage and use a soldering iron to heat up the motor-securing solder joint at the top of the motor bracket. Often the RPM of the motor would increase as any stresses in the motor mounting were relieved.

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#11 gascarnut

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Posted 27 August 2013 - 05:53 PM

Nice build...


Thanks!

 

I don't play with the F1 cars but I see that you tilt the uprights out to help support the 'over exposed' axle and I also saw that in SCRRA you are allowed (legal) to have "A frame" or wide stamped uprights.


Yes, the A-frames are allowed in SCRRA, but I don't use them, as I like my cars to be universally legal.
 

So looking at the picture the wire is 'not' in a figure 8 wrap... correct?


Correct, no figure 8. Just wrapped around the outside for three turns.

 

Does canting of the uprights with the wire wrap make it more difficult to reset the ride height?


Not much, but it does require good heat to melt the whole joint at once. As the axle moves down (or up), the wrapping wire slides along the upright and then inward (or outward) along the axle a little.
 
Re-setting a front axle that is wrapped always requires multiple heating and cooling, as you have to do one side a little than the other side, and go back and forth until everything is in the new position. I usually will end up by re-fluxing and introducing a little extra solder right at the end to ensure a good joint.


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#12 gascarnut

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Posted 27 August 2013 - 05:56 PM

Dennis,

You rule. Never thought about the flatness of the motor bracket. Makes a whole lot of sense. I will be checking ALL my cars now! :good:

 
Thanks, Bernie.
 
You can check the frames you got from me, but they should still be OK. I do this to all frames during the build process, but I would check them whenever you have the motors out as sometimes they can twist a bit in a crash.

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#13 slotcarone

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Posted 27 August 2013 - 07:10 PM

This is why you may have heard me say I spend an hour blueprinting the bracket before I do anything else. If you have a chassis that I built you should be able to screw in the motor with no binding. I also build the chassis with a motor attached to the bracket. Good use for FK motors!!
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#14 MSwiss

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Posted 27 August 2013 - 09:05 PM

 Are you sure that both the motor bracket AND the motor end plate are flat and square?

 

Dennis made a great point.

 

Not only will a flat bracket ensure not binding up the motor when tightening the screws, a nice fit of the bracket and motor face will ensure better heatsinking capability of the bracket.

 

Below are pics of two different motor brackets and you can see the difference between stamping the blank and forming it vs a CNC machined bracket.

 

100_0098.jpg

 

100_0094.jpg

 

100_0099.jpg

 

100_0101.jpg


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#15 Samiam

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Posted 28 August 2013 - 07:25 AM

More... more...
 
More details on brushes and springs.
Best height to set guide for braid depth.
What do you do for a loose car/track?
How do you make tire choice?
Where and why do you place lead?
What is that orange stuff I see on some chassis?
Front tires... hard or soft? Coated or not?
Body... forward or back?
Spoiler... yes, no? angle? size?
What type of chassis for type of track and conditions?
Pan movement... type and amount? 
Gearing... how do you determine best ratio for particular track and conditions?
 
Thanks!
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#16 Gator Bob

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Posted 29 August 2013 - 12:15 AM

Who'da hell are you? What'da ya think I am... a piano (wire) tuner?   :sarcastic_hand:
 

More... more...
 
More details on brushes and springs.


Please refer to your rule book. :D
 

Best height to set guide for braid depth.


Set it ON the track you are running... on a flat section that seems to be representative of the 'average' or "shallowest' braid depth ... right at the point that if the cars braids are flat and the fronts 'just' touch. If you touch a front and the opposite rear lifts us less/thinner spacer(s).
 

What do you do for a loose car/track?[


Softer tires, more spoiler angle, possibly more weight to the rear, mount body farther back, less gear (lower numerical ratio) if you are blowing the tires off the car.
 

How do you make tire choice?


Hard as I can get away with. Harder tires have less rolling resistance.
 

Where and why do you place lead?


Anywhere it needs it to balance out the car.
 

What is that orange stuff I see on some chassis?


Silicone rubber tape... used to dampen vibration or hammering of the pans.
 

Front tires... hard or soft? Coated or not?


Hard on commercial tracks! Coating is personal preference or track dependent, may cause vibration, consider truing after application.
 

Body... forward or back?


See above.
 

Spoiler... yes, no? angle? size?


Yes, as big as the rule allows. Angle, as flat as you can get away with (see above). No, if you can actually get away with driving it, LOL.
 

What type of chassis for type of track and conditions?


The $64,000 question.
 

Pan movement... type and amount?


See above... Amount... depends on which direction... LOL.
 

Gearing... how do you determine best ratio for particular track and conditions?


As low (numerical) of a ratio as you can go with consideration to motor temp, braking (two keys), and also torque to car weight ratio... see above.


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#17 John C Martin

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Posted 29 August 2013 - 05:08 PM

Sam, you're right most people won't give up their secrets to tuning... I aways have for what I do. They're all my opinion of course...

 

I think the spring tension is to much on PD motors (twieak, bend them to let the tension off slightly). Of course you'll gain RPM, but lose some brake, and lose some motor heat... and my best motor man suggests Big Foot 2 brushes, with Koford springs, 1301 I believe is the number.

 

Guide height IMO is just barely not touching front tires, I mean barely. I like to run the car several laps to see if they have raised the car too much to where the car will tilt out (usually the doughnut). My feeling is in a couple of lanes braid will be worn enough they'll still be making full contact and the tires will start to touch more.

 

Also the guide should slightly be tilted up at 3/32". Under front of guide with the guide not in a slot... so braid wears back to front. Of course this brings front tire height down also, so with tires up slightly, maybe only 5 thou, car is prime throughout the race...

 

Weight is where people disagree (back to tighten or loosen). As with anything there are limits or extremes... think of it this way, if you put hard tires on your car, are you going to gain traction by adding more weight to rear? (No). Way to fix it is softer tires... treated or untreated.

 

Testing is the answer to everything, hardest tire that hooks up to where it punches the doughnut... LOL.more weight in the rear is not my remedy for a loose car, slightly softer tire is, treated or untreated.

Besides my opinion is the weight in rear actually helps loosen the car with centrifugal force. I do like weight on the inside rear of a doughnut, for balance..

 

Body... high speed tracks don't require much spoiler (you'll kill straightaway speed.) Bend spoiler back and lower the back of body. With the hardest tire that'll punch the doughnut... test,test test, you're set.

 

Longer bodies can make the most downforce; also longest portion behind rear wheels as possible makes more downforce. More body in front makes more downforce on front. So to me downforce can equal weight front or rear (as with a wing car, no weight but tremendous downforce).

 

Pan movement... I like more movement. Forward to back and a little side to side, just a little...

 

Spoiler up for flatter tracks... down or thin for higher speed tracks.

 

At larger races the track will change due to temps in the building, glue conditions at beginning of day, and rubber build-up as day goes on... so it's a continuing test and change of tires to keep up with track conditions... this is why the best guys are on the track lots.

 

Gearing... I like to gear for not the longest straight but the shorter or medium one... say on a King the straight from the finger to the bridge (want most punch and best brakes in that section). Races are won on backsides, not the big straight.

 

Like I said these are my opinions...

 

I can only hope you guys that are fast will do the same. These are just toys, let's help our brothers... share your secrets..


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#18 John Streisguth

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Posted 29 August 2013 - 08:12 PM

Sam, if you ask the guys at the Retro East races they'll be more than happy to make suggestions. As both John and Bob have said, test and then test some more.  Not easy to do on race day so you may have to keep it simple, like tires and spoiler angle. After a while it becomes second nature.

 

One thing I have found that makes a big difference for me is to set up the guide depth for the shallowest braid section on the track. If I am setting up at home, I will err on the side of having it 5 thou too high. I have found if you set it too deep you will "tip out" where ever there is a shallow braid depth. This seems to be especially important on older tracks that have not been rebraided well.


"Whatever..."

#19 MSwiss

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Posted 29 August 2013 - 09:42 PM

Guide height IMO is just barely not touching front tires, I mean barely. I like to run the car several laps to see if they have raised the car to much to where the car will tilt out (usually in the doughnut). My feeling is in a couple of lanes braid will be worn enough they'll still be making full contact and the tires will start to touch more.


Another excellent suggestion.
 
I found the best way to check if they do, assuming the braid height is approx. the same on the straightaway, is to floor it out of the lead on, and "slam on the brakes", so the car stops in front of you.
 
If your fronts are still spinning, you need to pull .005" of shim out, until they don't.
 
Checking is easier if you are using BB fronts and with an F1 car.
 
With a Can-Am, GT Coupe, or Stocker, put a dot of contrasting paint on the outer wall of the tire you'll see from the driver's panel.
 
BTW, speaking of BB fronts, you know you have good ones if, when you fall off and walk over to get your car, they are still spinning.

Mike Swiss
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Five-time USRA National Champion (two G7, one G27, two G7 Senior)
Two-time G7 World Champion (1988, 1990), eight G7 main appearances
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#20 Hworth08

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Posted 29 August 2013 - 11:16 PM

A new racer can get a lot of info from Cheater's Champion T-Flex Tome.

Much of the info applies to all big-scale slot cars.

The tome is great for a checklist before going to the track too.


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#21 Gator Bob

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Posted 29 August 2013 - 11:50 PM

Tip.

Check to be sure the lead wires or motor tabs are not touching the body or the interior in full travel of the pans or full side to side or even downforce flex of the body.


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#22 Danny Zona

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Posted 30 August 2013 - 07:57 AM

I would listen to all of the racer's tips. The key is to go out on the track and test, test, test, then test some more. Never settle on just being fast. There is always more speed out there with some type of adjustments.

 

Sometimes its as simple as driving through a turn different that can take a .10 off your lap time. Just ask Jay Guard. LOL. He was going too soft in a turn at the Viper Pit race and I was like, "Jay, you have to hit the turn harder". He did and gained a tenth.


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Test, test, test and go test some more.
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#23 John C Martin

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Posted 30 August 2013 - 08:13 AM

The thing I see for newer racers I think is too much tape holding the interior in. I use the very minimum, letting it sag slightly in front... ideal is the body will twist and flex front to rear, and not be bound-up with a tightly-taped interior. I'm also very weight conscious in the body department, paint especially...

Danny, you're right... lots and lots of practice and testing is key. You and Biscuit do it more than anyone and it shows... although Tony P. was a close second; he's aways does great.


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#24 John C Martin

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Posted 30 August 2013 - 02:44 PM

Another little tip I just started doing to keep the pins in the body.

 

I put a very small dot of (9001 Surebonder high strength clear adhesive) on the outside on top of the pin head. It also adds some strength to the area around it... pins will stay with the body, no need to put those big bends in the pins.

 

After taking off 29 Can-Am bodies for the Viper Pit pictures some were really too tight... and some pin holes in the bodies were really worn out. This tip would have prevented that.

 

PS: Superglue is too brittle, the flexible adhesive works best.



#25 Cap Henry

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Posted 31 August 2013 - 08:11 AM

Here are a few things I do that haven't been mentioned yet.

 

I run all my Retro cars riding on the fronts. With the car in the slot you should be able to see the frame bow slightly without picking up the rear tires. Make sure the guide is always bent up slightly at the front, and new braids every race.

 

Make sure the body doesn't hit any part of the chassis or motor when it flops side to side.

 

Use good quality lead wire, replace it anytime it looks kinked or damaged.

 

Don't let the body drag the track

The single biggest piece of advice that hasn't been mentioned, is to learn how to tune your car between lanes. Things such as spoiler angle, taping the pans to limit movement, tire cleaning. Last year at Fall Brawl some tuning work from Mike Muir and Wes P changed my race from running last to second.


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