17 replies to this topic

[Chris Barnes]

Well, there was much talk whether the new JKX25 R chassis was going to be the next great thing - before testing was done.

Now that there are some built out there, anyone got any information positive or negative?

[Noose]

I saw only one run at out last race here in Retro East. It was good but cannot say it was a dominate car.

[Greg VanPeenen]

I have built one X25R so far with .062 main rails. First thing I can say positive for it is that it is a simple build. Anyone with basic soldering skills and some graph paper should be able to assemble it properly. This can be said for both new retro chassis kits the X25R and the Dragon Slayer III. Quality of the brass parts on the X25R is head and holders above JK's first offering. Material quality and flatness of the brass is outstanding on both the X25R and the Slayer III.

Sunday I did a little testing on the JK, built for super spec. at the Sano, seamed to have a lot of bite, I am thinking it would make a good flat track car. Testing was at Boogie Speedway 155 ft. Hill Climb. First off I tried the car with Koford soft wonder tires at .830. It felt good but got loose when pushed hard didn't deslot but the back of the car would start to come around. I then put on a pair of Koford Treated tires new out of the bottle again around .830 Dia. the car was to stuck with those and would lift out of the slot when pushed. Koford Soft Soft wonder tires would have probably been just right but I didn't have any with me.

The Dragon Slayer III is in the chassis fixture now hope to test my Sixteen rail version tomorrow. In its stock form the Slayer III is also a simple build. Next is an.078 rail X25R. More testing will tell the story on both these new Chassis kis

Regards,
Greg V.P.

[MSwiss]

I agree with Greg.

The .062" rail, X25R, seems to be an excellent flat track car.

I ran a real nice 5.25 on my flat track, with the car pictured, built by Lee Verdich.

Even more impressive considering it was done at a very light 106G+, (usually 118-125G is the ticket),
and using the "high tech" Koford rental controller pictured.

Attached Images

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[DOCinCanton]

I built an X25R with 1 and half 062 rails. The car handles great and was pretty easy to drive. I think my car came in at about 106 grams. GRRR has a race coming up this coming Saturday. I am thinking about giving this car a run in Can-Am.

[Les Boyd]

Last night we held the first Reto race at Fastlane Speedway, I had my D3X25R chassis kit assembled and ready to go. When it was put on the scale it weighed in at 109 grams. Most of the other cars weighed 130+ garms.
I had thought that I would have to add weights but in practice it ran like it was on rails and was putting up the best lap time.

Right from the start the car went straight to the front and was running very fast and handeling like a dream. After the first four heats I had a 14 lap lead. Then I had a little trouble, one of the motor screws came loose and it slowed down some. I found what was wrong and got back some of the speed (hurt the crown gear). Finished the race with I think a three lap lead. Next race the motor will also have some solder holding it in.
There was only one other D3X25R chassis on the track and he was having motor troubles.
Over all the chassis was very good in the high bank turns and was very good in the flat turns, may be too good. When on the inside lane of the flat turn it was almost too tight. I had to play with the controler to get it to come ut of the corner without a deslot.
We will see how things go the second time we race. If this chassis still works better than the others, or how many D3X25R are built and race.

[Les Boyd]

This kit has a great many things that can be done with it to change how it handles. On my second kit I changed where I attached the braces on the rear bracket. I moved them right in next to the main rails and the chassis was much looser than the first chassis where I had the braces all the way out to the outside of the bracket.

The second kit was stiffer and it made the chassis loose in the flat turn. But it was a bit faster through the high bank turn.

[MSwiss]

Les,
Thanks much for taking the time to post your mods and observations with the chassis.

[slotcarone]

Nice build Les!!! I see you had trouble wih motor screws loosening--if you are using the metric screws that the motors are designed for that is the problem. If you use 2-56 screws they will not loosen or come out from my experience and from the experience of the many racers that I build cars for or whose cars I work on. You can buy them locally at any Fastenal location or I know HVR sells them 4 for a buck which is a good price. You need 2-56 x 1/8 button head screws with .050 hex.

[MSwiss]

Or you can use blue Loctite if you want to use your existing screws.

[RPM]

From the lazy chassis builder in the world .Mike Swiss raced the first car built by RPM pretty much stock with 0.78 rails at the warm up before the Sano and got 2nd to Ron after turning 38 laps in one heat of the main. He also raced the same car at the Sano and made the move up from the D main to the B main. The car is much easier to build than the R-geo chassis as the same configuration. and probably would have made the A main if the one car finishing in front of him wouldn't have had possibly speed rubber? So as a car builder being the laziest one in the industry I would highly recommend the JK25 over the other chassis manufactures. Thanks Mike for racing my car.

[Josh Crutchfield]

I have to agree with Rande. This chassis is very easy to build. I built one for the 2nd ORS race at Tom Thumb Hobbies and didn't know what to expect. The car handled really well and could be pushed without desloting. It was a very basic build using double 062 rails. For the first time I was able to use treated rubber there. Pics can be found here.
http://slotblog.net/...race-2-results/

Josh

[MSwiss]

Josh,
Your performance at Tom Thumb with the X25R inspired Bud Bartos to finally build his.

In our conversation last night about other chassis parts, he went out of his way to mention he built it and how impressed he was
with it's performance on both the Rt.93 King and the Washington Flat Track.

He did comment on he felt at 111G's at Washington, he might of been on the light side, especially after picking up the
top finishing cars of the Lauterbach's .

He also used the term (or one like it) of being a basic build, but he did add that it had, IIRC, 4-.047" rails per side.

Maybe he'll spot this post and put up a pic of his car.

[Les Boyd]

I tried putting a bite bar on my second build to try and get it to hook up and it made a good bit of differance. The car now will hook up with treated tires and has a good hold of the track through the high speed dog leg and the flat curve on our Tri-oval.

And I also saw where James Merriman has put bite bars on the JK X25 builds that where shown at the Handicapped Race.

[A. J. Hoyt]

We have some newer racers here in CO. One exceptionally talented driver, Trevor, bought one of the new JK kits and we made an evening commitment last Thursday to build it up. I brought my Precision retro chassis fixture and offered to help build it.

 

The pieces feel odd, lighter than they look. We measured the thickness of the pans and it confused me as they were .029 by my calipers, an odd size (expecting .03125), I measured the rear motor bracket over and over and it seemed to have the right dimensions. I haven't installed axle tubes in a couple of years so that was new again.

 

We made it with two straight rails of .0625 piano wire, which seem to be what the pre-cut slots in the front pan and the remaining gap in the rear pans (after soldering in the rear motor bracket) were designed for. If one uses the gaps in the chassis components and evens them out (fore-aft), it pretty much dictates the wheelbase and the guide tongue to the front axle dictates the guide lead so there is no guess work.

 

We decided to solder the front axle to the front pan uprights and decided to let the bat pans "hang" on the stationary front axle through its front axle uprights, choosing not to cut them off.

 

The fixture tends to suck too much heat when getting that "good flow" of a proper solder joint, so I refluxed everything and put it on my hardwood solder board to finish it. It was still absolutely flat and straight and square after a final inspection on the fixture.

 

A single piece of .047 wire was soldered to the forward / lateral portion of the rear pan and to the aft portion of the rear pan through the bent-up tab in the bat pan to the portion limiting the lateral motion of the bat pans to the 3.125 maximum chassis width but allowing inward motion and upward.

 

Another short piece of .047 wire was soldered into the corner of the front pan front axle uprights going forward to the "wings" of the front pan and soldered there. This allows a bit of upward motion to the aft of the bat pans. The bat pans must twist this piece of wire to go "out of plane" and still rely on the front axle upright as a downstop.

 

Very simple. There must be hundreds of ways to attach the bat pans - this was just a quick way to get it on the track. Our very careful and deliberate build took less than 3 hours.

 

The entire car was only 104 grams with the body, RTR and it was a rocket on our 155' Hillclimb track, were very few Can Am cars under 115 grams ever work well. It was "planted" flat everywhere and really snapped around the bank.

 

We will, likely, do some axle tube reinforcement wires and add a steel guide tongue reinforcement later but it served very well in his first RMRRA race yesterday, getting a very competitive third place in his first race with his own car (I hate loaning him mine, he beats me with them!).

 

I wholeheartedly recommend this chassis to new retro racers that have some basic soldering skills. Ask for an experienced guy to show you how to prep the wire, how to apply the flux and show how to get a proper "hot" solder joint and loan you their fixture. I think Trevor gets a lot more satisfaction getting a third place with his own car than beating all of us with a borrowed car...

 

This is a car you can experiment with (bat pan attachment, lead positioning) because you can always go back to the basic initial build, which is pretty darned quick! Great job Jerry and anyone else who had a hand in designing and/or testing this product! Absolutely a bargain!

 

Keep it in the slot,

 

AJ

[Les Boyd]

I made a couple of changes to my second X25R, first on the first the axle tubes on the rear where bent from racing and I decided to reinforce the braces on them.  

I bent .055" wire in a U shape and ran it down to the back bracket on the chassis.

 I then took a .047" wire to make a bite bar for the pans to help limit their movement.

These two changes have made alot of defference, the first race that I ran with these changes saw me improve my lap total by better than 30 laps for the race. Not only that, all the way through the race I was setting lower and lower lap times even on the last heat. 

I have to say I have never had this much fun with slotcar racing as I have had building and running my own chassis builds.

RETRO is a blast.

[Les Boyd]

Sorry but I had a typeO I had run 3 laps more not 30.

[Rick Crutchfield]

Les, nice looking build! Hope you are going to make it to the Music City Retro Shootout in April @ Central TN Raceway in Lavergne TN.  Rick