First "FRAY" build...

[TuscoTodd]

With the elimination of the Magna-Traction class at the local raceway (parts were getting difficult to source and there were fewer and fewer racers that had them and/or were willing to "race" them) our local track has gone to a three class rotation of:
"HO Box Stock" (new era magnet car in stock form with slip on tires)
"HO Stock T-jet" (all stock parts, only motor brushes, rear slip on tires allowed)
"HO SS T-jet" (FRAY rules with stock arm).
Soooo - in order to not be left out and/or have to borrow a car every third week, I am going to put together my first "FRAY" style T-jet! :D

Have a pile of good used T-jet parts, some new pieces from the LHS and a copy of the "rules" from http://thefrayinferndale.com/rules/ - should prove entertaining! :D

Updates to follow! :D

[TuscoTodd]

Overall, this was a lot of fun for my first go around with these. :)
I was able to find an armature (red wire all three poles / gray lams - on a #2 top plate) in my pile of used parts that checked at 17.1, 16.9, 17.0 and had a relatively flat comm plate. Spent some time with 400 through 1200 grit papers and have it looking pretty well squared away now (sounds nice and smooth on the power supply)

Other than the comm tool - I don't have any of the fancy tools/jigs/etc. used for checking the chassis, top plate etc - but did use a couple pieces of drill rod through the axle holes along with a set of upside down utility blades to pic out what I think is a "good" chassis out of the spares pile. It is a #3 solid rivet and looks to have no notable twist to it using this method. :banana-dance:

The fitment of the Johnny Lightening blue/white magnets was next. (can definitely tell that they are stronger than what I have in my stock t-jets!) They both required a little time sanding with 400 grit on the two rectangular areas that face the armature in order to get them to drop into their holes - but it the amount of material that had to be removed to fit this chassis was minimal (and using my calipers, I and well in excess of the .700 min distance noted in the rules) :dance:

I am reusing the gears that were with the arm and top plate from my spares - they feel smooth and are nice and quiet - so not sure I would gain much by ordering up aftermarket gears...
This lead to the only real hiccup I had with the build - the rear axle... :?

I don't have a wheel press, but was able to fab up some inserts for pressing the new wheels onto the drill blank axle using old t-jet wheels, a short piece of t-jet axle and my Hudy pinion press - the combination of which, worked out rather nicely!
The problem I am having is, even though I am using .063" drill rod, neither of the two spare factory crown gears I have tried are very tight on the axle. If I try to roll over the drive train using the rear tires, the gear will slip on the shaft. :| I don't "think" it will slip under power on the track, as it does take some force to get it to slip - but it doesn't give me warm fuzzies... at all... :(
Is this normal and/or is there a common fix for this to allow reuse of the original gear (grind some flats on the axle and super glue?) - or am I stuck with having to order a gear / get creative etc if I want to use the drill blank axles verse a factory splined axle?
Any words of wisdom would be appreciated! :)

From there though, everything else seemed to fall into place rather well, with the Wizzard front end (wasn't sure where to start with the weights - so installed them all to start), new shoes and springs all going on and fitting well.
(The shoes look to be nice and flat against the rails of the old piece of model motoring track I have for doing "set up" - but not sure how the rail height of that compares to the rail height of the routed wood track at the commercial track yet - so some tweaking of those may be required yet.)

I think that the only things I have left to do is to chamfer the hole in the guide to allow the new beveled screw to fit up where it belongs and it should be ready for testing at the track this Wednesday! :D

If you guys have any thoughts on the crown gear issue and/or want to pass on any "words of wisdom" on this build or this class of car in general, I would definitely appreciate it!
Thanks! :D

And just so you guys know that it "really happened" - here are some pictures of the car as it sits right now (sorry didn't take any progress shots) - Enjoy! :)

Top side of the chassis:
(please excuse the excess oil on the top plate - have been doing "run in" on the power supply and hadn't cleaned it up for that shot)



Bottom side of the chassis:



From the side:
(I have to look to see if I can't get the front down a bit as it looks a bit "up in the air" with the small front tires on there - but I think I may be close to sitting on the top plate rails already)



From the front:



From the rear:

[ChallengerGuy]

While I can't quite tell by the pics, I am thinking you need to do some serious reduction in the travel of the shoes...in short, you fold the top forward to limit travel...the front wheel should lift off at the same time as the shoe does...if the shoe travel is not limited, then the shoe stays in contact with the rail as the front wheel comes off and you crash. So, bend those shoes to reduce travel.

Then, check your spring shoe tension to get about 2.0g of force. You don't want too much as you will pop out in the corners but if too little, the shoe won't make a solid contact with rail.

Have fun!

[TuscoTodd]

Thank you for the info on the shoes!
I saw the note about bending the shoes in the rules, but wasn't really sure what the purpose was - so thank you for both clarifying that! With having the reasoning behind why it is done, and what I should be trying to achieve - it should be something easy to incorporate.
(also appreciate the tip on the spring tension!)

:text-thankyouyellow:

[noddaz]

You will have to cut the rails on the gear plate to get the front any lower. Check your rules first of course. If no cutting is allowed find a different body that will sit lower.

Scott

[TuscoTodd]

Scott -
Thank you for the reply - I did some checking with some modeling clay this morning and you are definitely spot on about the rails needing to be cut before the body will sit any lower! The thickness of clay left after I snugged the screw down was the equivalent of a sheet of paper on the tops of the rails in the forward portion of the top plate (from the base of the windshield forward on the body).
After a little Dremel work on the forward portion, I ended up with the following...

(front sections of the rail removed - still have to do a little "clean up" to make the removal look pretty - but that is all the further I had to go back to accommodate the 'vette body)



The body now sits NOTABLY lower in the front! :dance:



Now all I have to do is determine what to do with crown gear (if anything?) and I should be good to go for Wednesday's racing!!!
:banana-dance: :banana-dance: :banana-dance: :banana-dance: :banana-dance: :banana-dance:

[ChallengerGuy]

Again, just a guess, but you want to remove the slop on your front axle...there should be zero, pretty much. The front wheels should rotate freely but there should be zero slop in the axle. You should also measure the exact width of your car and make sure it is not too skinny...front and back wheels need to be even...I am sure the rules say the width...when you run the car, you should see a nice solid line along the shoe...possibly like an hourglass so that that you know the contact patch is perfect. I believe the number we use for fray tracks is 0.12 rail height...you want the full flat part of the shoe resting on that height. The pin has a depth of 0.40 I believe...so you will want a longer than normal tjet pin, then cut to size (still longer than an original tjet pin I believe). I don't know if your cutting the rail height of the top plate is legal...it's simple enough to check though. Oh, for rear wheels, you want to run silicone on foam...typically 0.330 (or 0.326, 0.328) will get you where you need to be. About $10 a pair. Tungsten axles help add weight down low. Then, bring a dremel with a 200 or 400 grit flywheel on it to sand your shoes between each heat...and blue masking tape to clean the rears after each heat. Oh, and a controller that has a super light trigger...a fast, ball-bearing trigger and a ohmite 100ohm resistor will start you on your way. Just some hints. Feel free to ignore, just sharing info, that is all. :)

[TuscoTodd]

Thank you very much for the additional tips!
Based on your notes - I went to work! :)
Your observation on the front axle was spot on - I had .010"+ of play there - but not any more!
I am slightly narrower than the max width of 1.3125" noted in the rules at 1.298" - but both the front and rear axles are set the same. To get any closer to the max width, I will need to see about getting some .005" to .006" shims to space the front wheels out further (without putting my "play" back in)
On the shoes, the piece of plastic track I've been using as a guide actually varies from .015" to .018" depending on the lane and where you check it on that lane. I'm not sure what the rail height is at the local track - will have to check that tomorrow. I am at least "close" and will be able to use the magic marker method to see what I need to tweak. (and will look for that centered straight line/hour glass pattern)
On the pin - WOW - that is notably longer than my factory t-jet pin which checks at .195"! Will have to see if the track has any of those as that definitely can't hurt! :)
On the top rail removal, I went with the "Any amount of the vertical gearplate rails above the upper horizontal plane may be removed" noted in the rules - unfortunately I did nick a bit under on the one side - so I will have to see if that is acceptable since I only removed the front portion of the rail (not the whole thing) - or whether I need to dig another top plate out of the spares pile and use a bit more care (file instead of Dremel) - replacing the one that is on there now. (they may give me a pass? since I only removed a small portion of the rail - and not the entire thing - but will know more tomorrow)
For the rear tires - those are actually the silicon over foams that you mention (picked those up at the track) - so I should be good to go there.
Will definitely have to remember to take my battery powered Dremel with me tomorrow for the shoes - that will definitely beat cleaning them manually. :)
For cleaning the tires, I am used to doing the tape cleaning as that is how I clean the tires on my stock tjet and the Scalextric cars we run - but appreciate you bringing it up.

Again thank you for the tips! Should definitely help shorten the "learning / tuning" process! :dance:

[RichD]

You might want to look here for an article on tuning T-Jets: https://groups.yahoo.com/neo/groups/HOC ... CING/files
In order to see this you need to be a member of Yahoo! Groups, or you can send me a PM with your e-mail address and I can send you a PDF.

[ChallengerGuy]

I may be wrong on the length of the pin, but I know if you buy the dash ones, you snip just a tiny bit off...basically as long as you can go without bottoming out and whatever the rules state (if they state it). Cheers!

[TuscoTodd]

[ChallengerGuy]

Now you can start to imagine what would happen if you had a car that could pull away from those fast guys! Start by peening that idler gear post to the point where it does not fall off the top plate when you turn it upside down but still spins freely...try some slottech brushes and I bet you will find more RPM...be sure to try to have the brushes sit slightly angled in their resting position prior to installing the arm/plate. Oh yeah, you should also mark them with an X with a gentle carving with an xacto knife on the bottoms - this will prevent them from spinning and therefore prevent a loss of top end speed. It also allows you to rotate them 90 degrees at a time to find their respective sweet spots.