# Aurora T-Jet Chassis Hop



## Grandcheapskate (Jan 5, 2006)

Hi Guys,
A couple questions on the Aurora T-Jet. Let me just preface this by saying that all of my cars are using stock parts, mostly the parts they came with (except for the rear tires). 

(1) While running some Aurora T-Jets, I have some cars that hop a lot, especially at the track joints. I think I noticed a pattern where it seems that the hop is real bad on chassis using the short wheelbase (like a Mustang) and not a big problem on those with the long wheelbase. Get a car running real well, with a strong torque, and you can almost see it lift out of the slot on hard acceleration. This may be due to issue #2 below. Is the short wheelbase chassis more prone to hopping? Comments?

(2) When should the front wheels touch the track? If you remove the gear plate and put the chassis on a table, should the front wheels touch the tabletop or should the pickup shoe spings be strong enough to prevent this from happening until the gearplate (and it's weight) are in place?

(3) I have heard that restricting pickup shoe travel is a great tuning technique. I have seen one method of doing this (on the Vargo Speedway site), but I'm having a tough time with it. What is your favorite method to accomplish this?

Thanks...Joe


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## Voxxer (Oct 25, 2003)

*Hopping*

Hi:

On the hopping aspect - check your front tires, they could be out of round - this could also be for the tires. Replace them until the hopping stops - if the rim and tire are causing the problem.

Voxxer


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## dlw (Aug 17, 1999)

On your 2nd issue, the springs apparently are strong enough to keep the front wheels off the track (when removing the gearplate from the chassis). If you get front wheel hop when you run your car, your springs may be too strong. Try crushing them between your fingers to compress them.

I'm guessing you know about truing tires, but check your rims for trueness and also look for tree-nubs, or excess chrome paint blobs. You can feel these with your fingers........These can cause wheel hop. If you find any, just sand them off.


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## lbishov (Sep 21, 2004)

First thing you shoud do its to take the chassis and remove the pick-up shoes. Put the chassis on a flat surface to see if all tires touch, if not you have a tweaked chassis or all tires are not the same size, or some tires/wheels may be out of round.


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## LeeRoy98 (Jul 8, 2005)

*Restricting pickup shoe travel*

There are several ways of restricting pickup shoe travel including bending, using tape, shrink tubing,etc.
I have a tutorial on my website at www.marioncountyraceway.com for my personal favorite which is to cut thin slices from a rubber band and then slit and slide on the pickup shoe. Adjust up and down to fit your needs.
One note, I have had the best luck using a plastic feeling rubber band vs. the rubbery feeling bands. Also, I find they are much easier to put on the pickups with the pickups removed from the chassis.

Gary
AKA LeeRoy98
www.marioncountyraceway.com


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## Bill Hall (Jan 6, 2007)

Axles wheels tires are first around here. Junk rear stuff can affect the front too. I've adjusted quite a few unsquare chassis via tire truing and while they may not be a race winner they perform more than adequately. Unless it's a mile out of course LOL 

1. Shortening the wheel base lowers the guide pin fractionally so snagging is a possibility. Irregularities in the slot trough become apparent. So check it out. It's not guaranteed that the floor of the slot and the track surface are perfectly parrallel. Just because the because grade is flat doesnt mean that the slot is or vice versa. Investigate and dress the slot floor at the joint and or the tip of the guide pin whichever is required. Only takes a thousandth to boink ya.

2. Yes. Springs should lift a gutted chassis. If not your current flow will be poor(generalizing here). IMHO unloaded spring behavior is too far up the assembly line to be indicative of final car performance, unless it's excessively over sprung. While the added load of the gearplate provides the greatest settling of the pick up suspension, in my observation the final outcome is affected by the weight of the chosen body.

In my mind there are too many variables in the final assembly to put much emphasis on unloaded springs.

3. Restrictions of shoe travel for stock chassis/ride heights may not be helpfull at all. Travel restrictions are necessary for altered ride heights such as fray modifieds. It should be noted that many racers add weight in the form of collars and exagerated hubs. This compensates for the increased stiffness of running a spring nearer to coil bind. The restriction adds preload to the pickups. While the preload can really help current travel it can exascerbate slot hopping and handling if the commeasurate amount of weight is not added to the front axle assem. Conversly the drag racers use a wheelie bar or skid to limit lift and keep things planted. 

For stock applications shoe/spring tuning of what you have should be adequate. If you've determined that it IS infact slothop under throttle snap and not bad wheels or track irregularities, you'll have to adjust the spring tension. Dont forget that using a controller that isnt matched to your cars rating can contribute to the problem. If the car hops out any ole place on the track when ya crush the throttle your more than likely over tight. I like to remove half coil increments with the hobby knife. 

Then if the car lifts lightly initially and planes out a little spring crush may be order. If it still lifts or stutters opening the shoe hook at the hanger plate can lessen tension also. Be aware that if you open it too wide the hook can bind in the hanger plate.

The trick to shoetuning is spotting what and when its happening AFTER the wheel and track issues are no longer assumptions. By carefully watching how the car behaves and WHEN, you can then determine WHERE you need to start. Light lift or slight stuttering can usually be massaged out without mods.
Radical slot hop requires spring mods or replacements. 

It's a rather fine line for track tuning of stock setups. As you lessen tension your creeping up on limiting current flow and lackluster response and performance. As mentioned before some folks just add downforce in the form of weights or traction mag(s) like the AW Ultra G. Ya think AW fixed their QC problems related to handling?... Or did they just adjust the gravity of the situation too nulify the behavior? Not trying to incite a riot here...merely pointing out that there is more than one way to skin the cat.:thumbsup:

Shoe tuning is really not a black art as is often argued. It just takes observation and time to sort it out. While the fray guys have established an optimum spring resistance. This number reflects tuning an altered ride height with the added benefits of travel restrictions and forward weight adjustments. With different operating ranges comes the variables that can only be addressed with experience and the voodoo you obtain by repetition.

Hope some of this rambling helps Joe


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## Grandcheapskate (Jan 5, 2006)

Bill Hall said:


> Shoe tuning is really not a black art as is often argued.....With different operating ranges comes the variables that can only be addressed with experience and the voodoo you obtain by repetition.


 Hey Bill, which is it? It's either not a Black Art or I need to practice Voodoo. It can't be both! LOL!!!

I have been checking the rims and tires on the cars that are hopping and I do not see any obvious flaws. On the one car which did seem particuarly bad I replaced the wheels and it helped quite a bit. But, the hop and lifting are still there.

As you probably now, I have been working on really tuning up my plastic track. Right now, there are quite a number of cars that ride quite smoothly on the track, chassis ranging from T-Jets, AFX, Magna-Traction, Tyco, Tomy and Lifelike. And then there are chassis, within this group, that click, clack and bang (and hop) their way around.

So the question becomes...if there are a number of chassis which run well on the track, just how bad can the track be (for plastic track, that is)? If you have been reading my other thread, chassis such as the T-Jet will find more problems with a track the slower you go - it finds all the nooks and crannies in the slot joints because the slower you go, the more the car rides the slot wall. It seems the T-Jets which suffer from "The Hop" are getting it more from the pickup shoes than from anywhere else. And the cars that hop the most seem to be those with the short wheelbase.

Thanks to all who replied.

Joe


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## Bill Hall (Jan 6, 2007)

*Angle of the dangle*

LOL Joe!

I do not consider shoe tuning a black art! The shoe tuning spirits only present themselves after you've made the proper sacrifices. Perhaps a little like Voodoo, but only that it involves some curses and a trance like state to acquire the feel/knowledge. 

My "magic eight ball" now sezs the clacking and banging you describe indicates that your footprint geometry is nose heavy on the cars in question; again, providing the guide is not the culprit. Doesnt take much to make things uncooperative. A little upward roll at the forward edge of the contact patch can really help. This prevents the contact patch from rail plowing and toe stubbing at the rail joints. Regardless of the fact that the rail height is level the shoe will fall in the ditch instead of skiing across it. 

Your description implies that it is a random condition across your fleet. The observation that SWB cars snag worse is a good indicator. As the front axle goes back the contact patch shifts slightly noseward. I'd compare the burn/wear pattern between those that work and those that wont. I'll wager a baloney sandwhich that yer bastage cars have a pronounced forward wear pattern on the contact patch. 

Swamper Gene's site has good pics and intel on to how to accomplish it.:thumbsup:

This does not preclude the fact that ya may have to take some spring out. Lifting and snagging are different conditions.


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## SwamperGene (Dec 1, 2003)

Joe I know you said stock parts, but what about the guide pins? If they're JL pins, some will give you problems in Tyco track, they are not all equal. We raced stock T-Jets with stock ribbed rubber tires on my 18.8V Tomy a couple weeks back, my OEM joint bumps are dressed and that's it...when we run them it's not uncommon to run full heats with only one or two (and even occasionally no) deslots.


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## Grandcheapskate (Jan 5, 2006)

Bill and Gene,
Thanks for the input guys. As I played (ooops, I meant experimented) just a little today, I'm not really sure whether I am getting a little hop because of the pickup shoes or because of the dreaded Tyco flare. I also need to swap out the guide pin to eliminate that as a cause.

As you guys have probably seen me write before, I am using Mattel track and it has a 90 degree bend at the end of the rail, unlike Tyco which is straight, and also that annoying flare. I'm closing in on a cure for the flare by the way. The 90 degree bend may also not be long for this world.

Just as an aside, the Tomy Z bend in the rail is probably not as big a problem because the angle is less, maybe 45 degrees?

It is my opinion that a lot of the clicking at the track joints is not so much from the rail height difference between track pieces, but from the fact the pickup shoe is encountering a rail at a 90 degree angle to the direction of travel. Think about it. The noise (and resulting hop) a shoe will make when hitting a raised rail is going to be a lot louder and more pronounced as the surface/contact area increases. On regular Tyco track, the rail is always parallel with the shoe and therefore there is very little surface area when the shoe encounters a raised rail; only the width of the rail. Put the rail at right angles to your direction of travel (about 1/16" to 1/8") and the shoe has a lot of surface area that it hits.

Ever use the Aurora 90 degree intersections? Ever have problems with cars deslotting when they hit the cross rail? That cross rail is on every piece of Mattel track. The more a shoe tends to lean left or right, the more pronounced the slamming into the rail bend will be. The stronger the springs, the more a raised rail will be a problem.

Now, combine that with the slot flare. Magnet cars (and AFX cars with bladed pins) are not effected by the flares as much as T-Jets. My T-Jets (some more than others) really get effected by the flares. On the straights, if you get behind the car, you can see it wiggle all the way down as the thin pin rides the slot wall - in and out at every flare, banging into the slot wall (as it crosses to the next piece) and being thrown back into the center of the slot at every joint. Not just that, but there is a small gap in between each track piece. The T-Jet (and AFX) pin is small enough to find that opening, especially when going slow and riding the slot wall (a blade pin rides this out much better). Think about this again; when you ride the slot wall and come to the flare, you are being taken toward the edge of the track (now going at a slight angle) and directly into the joint gap. Go slow enough and the pin finds that gap and the car can actually get stuck there - or thrown backwards. Go fast and you (most times) blow right over it.

So, the hop is for two track related reasons. One is the rail being at right angles to your direction of travel and the other is the $%$#&* flare. Strong pickup shoe springs, selected guide pins and a short wheel base may just add to the problem. Put a car with weak springs, a blade pin and a long wheelbase on the track and it sounds and rides pretty smooth. Put on a Microscalextric with braided pickups and the only noise you hear is from banging the flares. 

So, what to do? My Tuning Plastic Track thread follows my agonizingly slow progress toward finding a method of filling the flares; this also has the benefit of closing the gap between pieces. I am also going to bite the bullet and cut off the 90 degree bend on a select section of my layout where 5 6" 1/8 curves are in a row - this is click clack central. I will then fill in the flares on those pieces and see what happens. My guess is a bulk of my problems go away.

The sad part if this works? This could have easily been done when the track was designed. If it works, you can be assured it will be designed into any future pieces I work on.

Thanks...Joe


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## dlw (Aug 17, 1999)

Joe, when you come across a Tomy track 'Z' rail at the joint that sticks up, you can bend it down just below the adjoining straight rail to keep tjets (and other cars) from getting thrown off the track. Can you push the Tyco bend down a little without causing a problem?


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## Grandcheapskate (Jan 5, 2006)

dlw said:


> Joe, when you come across a Tomy track 'Z' rail at the joint that sticks up, you can bend it down just below the adjoining straight rail to keep tjets (and other cars) from getting thrown off the track. Can you push the Tyco bend down a little without causing a problem?


 I don't think so. I just tried it now and had no success. My only choices seem to be (a) cut off the bend or (b) file it down.

Filing it down will be difficult and time consuming. Cutting it off takes no time at all with the Dremel and a cutoff wheel. I experimented with a junk piece of track and after cutting off the bend, the electical contact seemed to be unaffected. The bend was designed into the track in order to improve the electrical connection by providing more tension to keep adjoining rails together. In that sense it works, but I don't think it was necessary. Putting a slight bend into the straight rail accomplishes the same goal without the unintended consequences of a cross rail.

I'm posting a couple pics in my Tuning Plastic Track thread which shows the flare, my filling experiments, and the rail bend.

Joe


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## mahorsc (Mar 26, 2008)

hello every one this is my 1st post so bare with me 
we use a finger nail file on the track joints it smooths out the edges its done after all the track laid down and leveled piece to piece 
its hard on the fingers and it takes time but works great
almost the only thing we run are t-jets 
other things shoes must be flat no leaning
car seem to need just a little more travel in the shoes have cars that are great on routed tracks but bounceon plastic just add alittle 
softer front tires help (orings and bsrt seem to be better than the hard tires that come with wiz frt ends they are so quieter
my 2cents 
thanks kevin


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## tjettim (Nov 29, 2005)

The Black and decker sanding "Mouse' works wonders
on track joints.Use very little pressure and fine sandpaper.


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## vaBcHRog (Feb 19, 2003)

Grandcheapskate said:


> Hi Guys,
> (3) I have heard that restricting pickup shoe travel is a great tuning technique. I have seen one method of doing this (on the Vargo Speedway site), but I'm having a tough time with it. What is your favorite method to accomplish this?
> 
> Thanks...Joe


Joe you heard right it is one of the best things you can do to make the car handle better.

First and most important is true axles, wheels and tires. You notice the difference immediately.

Next is a set of the modern motor brushes

Then lapping the gears.

You should now have a smooth and fairly fast TJET however it will deslot easily in the turns.

Now to the pickups. You need a flat surface with a hole for the guide pin. I use a tech block with a hole drilled on the bottom.

Now get some Alcohol a Q Tip and some small scissors and scotch tape

Place the car in the guide pin hole.

Look at the front of the car at the pickup shoe window.

Clean the Pickup shoes on the front window area with the Q Tip.

Cut a piece of tape and lay it on the pickup covering all the front area above the chassis pickup tab. Now trim the excess tape around the pickup. Now repeat on the remaining pick up.

You will notice that the pickup barley travels up and down. Also if you hold the chassis upside down and look at the side you should see that the flat side is just above the bottom of the front wheels.










Now test it. You will notice that you have lost a little top end but you should get through the corners much much faster. Also you should notice where the cars rear end use to stick then break lose and deslot it will not slide smoothly out.

I have also used small pieces of card board super glued to the front of the pickup and even paper. I have used a flat tooth picked slid into the pickup window then twisted sideways till it was snug then trimmed the front and back of the tooth pick.

All of this are temporary restrictions and can last for a full race. Heat shink and the rubber band also work however when I did it the back of teh pickup would hang and I had to bend the pickup out.


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## Grandcheapskate (Jan 5, 2006)

Thanks Roger. I will give that a try.

Joe


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## oldraceral (Dec 1, 2005)

My favorite way to restrict the pickup shoes is to solder a very thin piece of brass on the backside of the pickup. 
I tin a long piece of brass and clamp it to the edge of a wood block. After cleaning and applying a small amount of flux to the backside of the pickup, position it on the brass strip with about half of the opening covered. I use a tweezers to hold it in place. A light touch with a soldering iron and hold it steady. I'll do about 6 or 8 at a time then trim the brass as close to the pickup as possible. Use a jewelers file to tune each opening of the shoe to a particular car. If you open it a little too much, use it on a car with a little taller tire. You may also have to open the bottom of the hole to allow some movement there as well.
Legal disclaimer....This isn't legal for Fray rules, but our local club allows it.


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## Grandcheapskate (Jan 5, 2006)

oldraceral said:


> My favorite way to restrict the pickup shoes is to solder a very thin piece of brass on the backside of the pickup.


 Another interesting approach. I'll have to locate a thin brass strip and try this. Sounds like a pretty quick operation.

Thanks...Joe


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## Bill Hall (Jan 6, 2007)

Grandcheapskate said:


> Another interesting approach. I'll have to locate a thin brass strip and try this. Sounds like a pretty quick operation.
> 
> Thanks...Joe


A guy could always cut out the middle man and just solder the top of the window closed. Then jewlers file it to the required restriction.


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## noddaz (Aug 6, 1999)

*Unfortunatly...*



Bill Hall said:


> A guy could always cut out the middle man and just solder the top of the window closed. Then jewlers file it to the required restriction.


Unfortunatly not legal for the type of racing I do....
(But I may try it anyway... lol)

Scott


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## Bill Hall (Jan 6, 2007)

LOL Scott, Prolly the same rule set that allows sumo front hubs...but a quarter gram across your pick shoes ?!!!! .....Heavens no!...Now if ya wanna add schlubber bands, shrink toob, gasping tape, or mutilate them with the noodle knees pliers; well that of course is OK!


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## LeeRoy98 (Jul 8, 2005)

vaBcHRog said:


> Heat shink and the rubber band also work however when I did it the back of teh pickup would hang and I had to bend the pickup out.



Roger, sizing the rubber bands is a matter of experimenting but once you realize how small you can make them it solves hang up on the chassis. I had the same problem initially.
I like the rubber bands because we travel to different venues and I can quickly adjust the travel up or down to suit the rail height on different tracks. Kinda like adding a round of wedge on a pit stop! I have also found that almost every chassis I have experimented with responds to even the slightest extra restriction.

Gary
AKA LeeRoy98
www.marioncountyraceway.com


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## vaBcHRog (Feb 19, 2003)

LeeRoy98 said:


> Roger, sizing the rubber bands is a matter of experimenting but once you realize how small you can make them it solves hang up on the chassis. I had the same problem initially.
> 
> Gary
> AKA LeeRoy98
> www.marioncountyraceway.com


My problem is all my xacto blades are dull from the resin body work so I can't trim a rubber band worth a darn.

Roger Corrie


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## cbwho (Dec 14, 2021)

vaBcHRog said:


> Joe you heard right it is one of the best things you can do to make the car handle better.
> 
> First and most important is true axles, wheels and tires. You notice the difference immediately.
> 
> ...


I am quoting the above because it's so marvelous. Mangling the top of the hook doesn't work. The tape trick is adjustable and easy to do. And only requires the removal of the body. I put tape and the backside and front side and trim with xacto and pinch with tweezers.










If by chance, you must install pick ups: I found installation of the springs to be a nightmare without some sort of spring compressor: Scotch tape that has a middle band wrapped.


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## cbwho (Dec 14, 2021)

Just tried the rubber band wedges








😁


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