What makes a car deslot?

[slothead]

I've been running time trials for about 4 dozen Trans Am slot cars, more than half of them Scalextric RTR cars with Paul Gage tires. A full run at Shelby-Hendrix Speedway is 30 laps, 5 of which are used to calculate a qualification time. The other lap times are used to create a statistical profile of the car.

I've been doing this for years and can push most cars for 30 laps without incident. But, one car, a Scalextric Mustang, consistently deslots after 11 - 14 laps into a run. Coming out of a turn it simply lifts out of the slot. This tends to happen in one of 2 turns, both right turns, but can happen anywhere on the track. It doesn't spin out or crash, it just comes out of the slot and usually ends up about an inch away. I've run other cars in between attempts with this Mustang and not had any problems, so it's not the track.

I checked and the chassis is flat and all 4 tires sit squarely on the setup block. The chassis has been sanded and body screws loosened a bit to create a little body float. The stock guide isn't loose and seems no different than any other car.

I'm thinking of adding some lead weight to the front part of the chassis but wish I knew what was going on with this car that isn't happening with similar cars. Anyone else had this sort of problem with a car and figured out the cause?

[ccobra]

This should be interesting for I have the white Scalextric 69 mustang runs real good like turning in 4.19 second laps when all of a sudden it just goes airborn. It's mostly stock except for the CB design wheels with silicon tires and a 34t slot-it sprocket.

[Czar]

Cars de-slot because, as the car moves through space, accelerates, slows down, and responds to centrifugal force, the center of gravity changes the center of balance in the car. This is why putting weight lower is not always the best answer for handling problems. Sometimes, a little weight up higher can make a significant difference in a car's handling. I should also add that because the car is guided by the keel in the slot, leverage will also play a role in whether, or how easily a car deslots.

[Pappy]

My "guess" would be a front tire problem. Have the front tires been trued, do they rotate freely with side loading, are they hitting the body when the body leans in a turn?

[Kevan]

Guides with too much side play + floppy front axle + too much front tyre grip + too much front tyre clearance + not enough guide in the slot + a few other things like body tyre rub at the rear can all cause deslots.
...add weight up front until it stops...never had any luck adding ballast up high.

[RichD]

Based on what you have said I believe that the Mustang needs a little more weight up front. The weight should be just behind the front axle and on the bottom of the car if there is enough clearance. A couple of grams of thin lead sheet should do the trick. You never want to have the guide flag come out of the slot before the back of the car slides out.

[model murdering]

This is interesting ...

" But, one car, a Scalextric Mustang, consistently deslots after 11 - 14 laps into a run."

How is it on laps 1-10 ?

[slothead]

I really appreciate the feedback. I'm going to fiddle with the car later today and see if t improves. I'll start with checking out the front tires, maybe they are out of round and lift the guide out of the slot at times.

On laps the car stays in the slot it's running well, comparable to the other Scalextric cars in the class. That's what makes the deslots so odd, they seemingly come out of nowhere. Sometimes when running a car 'on the edge' you know the least little mistake will cause a deslot. With this car I run fast but am also fearful of deslotting so I try not to go to the edge, then it deslots anyway.

One thing I didn't mention before - when I first got the car the guide would sometimes fall out after a deslot. I put a small screw in the X pattern on top of the guide post to widen out the knob that holds the post in place. I've since removed the screw and the guide turns freely and no longer falls or pulls out. Nothing obvious there now.

This is a nice looking car and I don't want to have to make a shelf queen out of it.

[mattb]

DRIVER........... trying to get more out the car then it is set up for.

[chrisguyw]

If you have checked all of the possible causes of a front end deslot, (mentioned in prior posts) it is likely that a bit of weight low and just behind the front axle will cure your problem,.....but,....I would re check all of these potential issues before adding any weight, as if any of these issues exist, you will be just masking an issue that will still be there, and one which will continue to impede lap times. As a general rule, after ensuring that everything else is good....true 4 wheel/tires, no rubbing of tires on body (check for rubbing when the body tilts on the chassis), front tires (true) on the track with little/no upward travel, etc, etc, etc., test the car, and then weight is the last thing to be used for fine tuning.

Since your issue is intermittent, my inclination is that there is a small issue somewhere, one that seems to randomly affect the cars handling,........double check to be sure that there is no rubbing of the tires on the bodywork,....not only when the body is square, but, more importantly, as it rocks from side to side.

Hope you sort it out, and, let us know how you make out.

Cheers
Chris Walker

[waaytoomuchintothis]

I had a mysterious situation like that once, and I eventually went to look at the spot where it happened most frequently. The guide on that particular car ran just a bit deeper in the slot, and almost invisibly, in the very bottom of the slot there was a little clump of crud. I couldn't see it at all. I drug a screwdriver along the bottom and it popped out. The car never did it again. How's that for weird? I'm sure you will solve this by one of the methods above, but just in case, look in the slot, just for me.

[Wobble]

Your Mustang sure looks to good to live on the shelf. Another possibility might be too much grip on the rear or rear left tyre/tire not rounded off enough on the outer edge so car tips lifting guide instead of sliding/drifting sideways a bit. I have one Scaley Mustang C3424 that I've spent quite a bit of time on to get it to keep up with their Camaros but it seems to be a hard nut to crack..

[slothead]

I took the Mustang apart and tried a few things. First I removed the front tires and filed off some flashing on the wheels. Then I used the Dremel to remove some plastic from the bottom of the interior and top of the chassis (brackets to hold extra magnets and nubs to route wires between). This created a flat area I could stick some lead to and press into place. One of the rear body mount screws was missing so I replaced that.

I removed the guide (it pulls out easily since the wires don't connect to it, little tabs press down to make contact with the top of the braid) and tried some replacement ones but they were all too loose. Ended up putting the old guide back in and fiddling with it so it was secure and turned freely. I suspect the guide is the major factor in the desloting problem, but didn't know what else to do.

Back on the track it ran better and I was able to do a full run without incident. I think I saw the inside rear tire lift off the track slightly a few times exiting a turn, but the car didn't lift out of the slot. The car qualified 17th out of 35 cars so far, so no complaints there. But, I think it can still be made more reliable by sanding the front tires, taking some of the up/down travel out of the front axle, and rounding off the edges of the rear tires to ensure they aren't 'digging in' on corner exit.

Without switching to an aftermarket guide which could provide an unfair advantage, I can't think of much else to try. But, the feedback you guys provided has helped a lot and made the car driveable as it is now.

[Kevan]

Take almost all the play of the front axle out by putting a long piece of lead under it just leaving a few thou' clearance. Then sand the front tyres down until they sit almost but not quite touching the track, then coat the front tyres with superglue then polish again...then report back