20 replies to this topic

[Krash]

Ok guys looking for some tips and pointers here on my first retro, I have a Slick 7 S-635 chassis that I put together. The cars is what I consider to be very loose and lacking traction, in the corners it will sling completely sideways,coming out of the leadon to the main straight it will fishtail many times before finally settling down, at this point the car is un-drivable for racing.I have tried four different kinds of tires, changed the size of the bit bar connecting the pans, added a full square of lead weight to the rear and although I might get a little improvement so far nothing has really helped. I would ask for help locally but no one else is currently running retro's at our track. (165 ft.Engleman)

Chassis is basically simple torsion setup, two .055 main rails, .055 bite bar, JK Chem Treated tires, 8/28 Gearing, all four tires are sitting on the track – I have added and removed guide washers. What other info do I need to add?

Thoughts?






Kelly

[Cap Henry]

Have you tried a smaller bite bar to let it flex more?

[Prof. Fate]

Hi

Or add a tooth to the pinion.

Fate

[slotcarone]

The most important thing to know is what are other cars doing on the same lane? Nice build!!!

[MSwiss]

You referred to 4 prs. of tires before referring to JK chem treated.
Try non-treated(softer) tires with a small rim like JK 8703P.

Also,what body are you running and do you have a 1/2" spoiler on it?

As mentioned before, nice job building the chassis.

Mike Swiss

[tonyp]

Body and tires will make a big difference. Alpha tires are 1 grade softer than the JK. If you don't have enough bite with small rim JK's try a set of Alpha untreated. First thing is the body before you go tire crazy. What kind and are you running spoiler? Bodies make a big difference. The chassis loks fine and should run well....

One last thing.... Does your controller have enough adjustment so you can slow it down enough to ease on the power, especially on a flat track.

[Krash]

To try and answer everyone's questions:

Bite bar – yes down to .047, have not tried anything smaller…

Pinion – No, didn't think this would help.

Other Cars – as stated no other Retro's – Flexi's with Falcons can do low to mid 4's I would think I could get to 5's with a retro? Currently about 6+

Tires: don't remember all of the numbers, the track owner setup about four sets and let me take a few laps on them. JK untreated, JK Treated, large hub, etc. I will need to order some Alpha's local track does not carry them, currently have JK8713PT on the car.

Body – JK Ferrari 612 with spoiler (oversize)

Weight = 108 with body.

Controller – Standard older Difalco

This thing is LOOSE! Like I am running on old dry tires! Spins and slides everywhere, I am not trying to tune a few 10^ths but get it drivable at this point.



Once again, Thanks.

[Craig]

Kelly,

If your car is that loose you need to try any brand untreated tires to start. Additionally, try the TI-22 body as it will give you more down force. If that doesn't work, you may want to try changing the chassis from torsion to hinged pans. I haven't had the best luck with torsion cars but I have with torsion floppy style chassis.

Hope this helps.....

[tonyp]

Agreed.

[endbelldrive]

Thoughts? I haven't built the Slick 7 S635 frame but the mainrail/bite bar combo does look a little stiff to my eye. The first thing I would do is take a fine saw and cut the outside solder joint on the outside rail at the front...to free up the flex on the mainrails.

[macman]

Go with Craig's advice & go to floppys... In general, tortions work best on swoopy kings where you don't need as much chassis flex ... On a track where you do need flex, floppys will be to yuor advantage. Also try adding some weight to the rear of the pans.

[Phil Irvin]

Go with Craig's advice & go to floppys... In general, tortions work best on swoopy kings where you don't need as much chassis flex ... On a track where you do need flex, floppys will be to yuor advantage. Also try adding some weight to the rear of the pans.

Go with the floppy wings. Put the hinges as far apart as you can. About .030 lift should give you a good starting place. IMO 107 Gs, with body is about 10-12 Gs lite for that stiff a chassis. Add weight to the out side of the wings. Start at the center and move to the rear.

TEST..change....TEST....change... It will take some time to learn what does what....Or just ask and we shall point you in the right direction. HEHEHE...Usually...It is very seldome that a chassis is nutz on..The first time out. I don't care who builds it!
OLPHRT
PHIL I.

[NJ Racer]

That chassis looks perfect and should not be as loose as you describe. I think you are either using stale tires, or the track surface is just crap, at least the day(s)you tested.

[Rick]

I would remove that bite bar, solder on two 1/16" collars, where they are soldered solid on the outside, use a new piece of .055, possibly .047 for the bit bar, solder or limit it into the center tubes and try it again. It's pretty much just solid now and very stiff. If you use limiters(side to side stops) on the bite bar you could remove and change it out with one solder joint and try the other diameter wire............

[slotcarone]

I agree with Ray-that is why I asked how other cars are running on the same lane. Take a Flexi car on the lane first and when that is hooked up then put the retro car on the track and try it.

[Josh Crutchfield]

Krash,

All of the above is good advice. If you leave the chassis as it is I would use a .032 bite bar and do away with the brass tubing on the rails. Just bend hooks out of .032 wire and solder between the frame rails. This would give more adjustment. You could also add shaker bodymounts. As mentioned before, Torsion cars can be difficult to tune. I tried building one per the included directions and could never get it up to speed.

Here is a pic of what I finally ended up with. It handled very well and easy to drive.

[Steve Deiters]

Josh,

What diameter are the main rails on your chassis?

[Jay Guard]

Krash:
First of all I want to say what great job you did building the kit, really first class. It looks like you did everything right so it's surprising that you're having such a big problem with traction, which I have to say I haven't experienced with this car. My initial thought is to go with natural fish rubber and make sure the track is correctly sprayed. If everyone before you has been using Kelly Bulldog tires that can also make the track very loose unless you are using them too. Once you're sure everything with the tires and track is correct there are quite a few mods you can make to this chassis.

First, there are a number of things that make the S7 a little different from some of the other Retro Kits out there. It's made of .040" thick, very high quality brass and is therefore a good bit stiffer and stronger than most of the other kits. When combined with two inner steel rails on each side it can be a bit too stiff. If you want to keep it as a "torsion" car I would do what Josh has recommeded (i.e. remove the tubes, make the bite bar 1/32" steel) and in addition I would make a 45 degree cut from the "inside corner" forward and outward toward the front wheel approx. 1/4" long. This will allow the side pan to move a good bit more than they do now. I would also change the inner rail to 1/16" brass. This will dampen the chassis movements and allow it to flex more. An additional mod that I would recommend is to extend the guide tongue approx. .150" giving a guide lead (distance between the front axle center and guide post center) of approx. .900". Even with these aggressive mods I guarantee there will still be plenty of strength left.

If you want to convert your car to a floppy pan style I would still go with the brass rail and guide lead extension and then build it like mine (shown below) or Josh's. One of the things to remember with the floppy pan car is that you don't want too much movement up or down. Probably something in the .030"-.060" range.

[Krash]

OK Guys, Thanks for all of the tips...It looks like I have a lot of work ahead and only one weekend until our first retro race.
In general I will start with the tires and changing the bit bar as suggested, then move toward changing the main rails and going to floppy's if needed.
Basically doing the less invasive work first and moving forward.

Next question, if the Slick is stiff then am I in trouble with this one also?
.063 mail rails - .055 bit bar not connected in tube with about .025 of movement in the pans

Thanks again

Kelly

[Phil Irvin]

Yeah kinda. It does look good. One of mine is very close except I didn't solder the wire together except at the mounting points. I would make the wings independent with about .045 movement. If the rear won't slide. Add 1/4 X .062 brass bracing at the rear of the motor mount. Rear weight down low.

OLPHRT
PHIL I.

[A. J. Hoyt]

Kelly,

I came to this late and may have missed this suggestion. Listening to the general state of "looseness", my first guess would be that the rear axle may be very slightly bent. If you use the wrong material for the axle, it doesn't take much to bend it "just enough" to get that kind of behavior everywhere around the track.

All of these other suggestions are good (they are the experts) but you have a very good, basic go-kart of a chassis. If everything is straight and aligned and all of the parts run true, it should still run like Jack the Bear and NOT exhibit this kind of general tail-happiness.

Most any chassis design can be tweaked and made to work reasonably well. The best chassis are, of course, easy to drive fast and consistently, so that is the goal.

I am the last one that should be offering this advice but everyone needs to get all of the basics down. I am not sure I know all of the basics yet, but true-running parts are definitely one of them.

Looking forward to your report of what actually cured the problem.

Keep it in the slot,

AJ