I always thought a low rear/high front made the rear end a little calmer whereas a high rear/low front makes the rear skate around a little more.
This would seem to follow my experience in RC car racing, 4wd always had higher rear end to enable the rear end to slide more, 2WD always had higher front end to enable more rear grip.

 

Not sure about the "rake" and "guide angle" but... Some times going into a corner fast and braking at the last possible moment, will cause the weight to transfer to the front of the car, pushing the guide down into the slot, keeping the car on course through the corner. While going into a corner at a slower constant speed , will not put the extra downward force on the guide, and the car may de-slot. Accelerating transfers weight to the rear, so with enough power and grip the guide can lift out of the slot even on the straights.

 

A few RTR Scalextric and Carrera cars have a higher front end which I find detrimental to handling and also looks. I've not kept any such cars but a simple solution is to add 5-10 grams weight towards the front end. In addition, replacing a spring-loaded guide helped keep cars in the slot, and avoided 'bouncing' between track joins down a long straight (a lá my old Ninco but since have switched to Policar). Personally I think a flat, low level chassis is the way to go.

 

If you'vre got F1 size tyres on the rear it seems like you're not averse to having different wheel sizes, so why not have slightly smaller diameter wheels on the front.
ps. Welcome aboard SRD.

 

Hi SRD

Deslot could be caused my any number of things. What’s the track surface? What’s the relationship between the front axel height (meaning tyre) and the guide height? What front tyres are you using? How loose or stiff is the body? Does it happen on corner entry or exit?

You can keep your nose up and shim the guide to stay in the slot if that’s how you’d like to run it.

Some good discussion above. The only other influence rake has on full size vehicles is aerodynamic- which of course we don’t have to worry about with our cars.

 

@SRD since you mentioned printing your own car I will point out that most chassis designs have the guide tongue flat on the printing plate. That causes the front end of the car to raise up.

Raising the guide tongue off of the printing plate will help lower the front end but you will have some support on the bottom side of the guide tongue to clean up when your print is complete.

It also depends on the type of track you use and whether you can run a deeper guide flag or not. Aside from all of that the foregoing discussion about chassis dynamics is useful.

 

@SRD since you mentioned printing your own car I will point out that most chassis designs have the guide tongue flat on the printing plate. That causes the front end of the car to raise up.

Or have a separate guide mount that sits on top of the chassis (nearly all mine are like this)

 

Awesome feedback all, thanks so much!

I'm running on Scalextric sport track,
The wheels, tires and axles come from an old Scalextric parts pack (pit lane spares 31)
They have quite large 21mm dia tires on a small hub, they are about 13mm wide in the rear, 9mm for the front. (I think they were common on 80s-90s F1 cars)
The rears have been crudely trued and the fronts are still a little lumpy.
Currently the guide tongue is flush to the bottom of the chassis and holds the guide 9mm in front of the front axle.
When on a setup plate the front tires just skim the surface. (Basically guide and front tires are the same height)
Due to the design the body and chassis are rigid but it does have a floating pod in the rear.
The occasional de-slot tends to happen mid corner when going a little slower than normal, cruising round the corner rather than braking in and accelerating round the corner, very similar to Dave D Stevens description.
Cheers Kevan, really helpful! I was thinking almost completely backwards of this, but the more I think about your comment it makes a lot of sense.

As chappyman66 said the guide tongue is flush to the base of the chassis, and causing the nose to ride a little high.
Yep Kevan, I think that's defiantly the way to go!

I will try and get a couple of pic's up over the weekend, to help explain a little more.
I will separate the guide tongue from the chassis and make it a screw on part this will allow me to play around with different front ride heights.

Thanks again everyone

 

This is one of my chassis, it's a Ninco Jaguar XK120.
Guide block is glued to the top of the chassis.

This is for an upcoming Targa Florio Proxy.

And this Fly Corvette is currently dicing for the lead in a current proxy on SlotRacer Forum.

 

This is one of my chassis, it's a Ninco Jaguar XK120.

Excellent body mount positions, it gets a tick from me.

 

Oh, very interesting, thank you!

I like the brass tube bushings, really compact and versatile.
Your pod design is really intriguing, how is it fixed at the front?
Does it pivot on a horizontal screw going into the body post?

Funny, I just picked up a fly corvette, very funky with their front mounted motors.
Fly do a great job of the bodies and interiors.

As promised, here's a few pic's of what I'm playing around with.
Apologies for the poor images.

Its a BriSCA F1 stock car, this is the original design with a fixed front tongue.

The body is a little wider than it should be to accommodate the inline pod.

Here's the underside.

I think I will swap out the washers for fiber washers, regular ones are a little jingly.

Below is the new chassis design and tongue, it lifts the guide by 1mm.

I totally screwed up hitting 1/32 scale, I scaled it around the wheels and motor pod without taking much reference from other 1/32 cars, so it ended up quite large.
Closer to 1/28 to 1/24 scale but it still runs great on regular Scalextric sport track, two of them would probably be quite tight, but hey, rubbings racing!

Here is it next to my corvette for scale

I may separate the side pods so they can printed in another colour.
I always think the air filter looks too small, but maybe it just because the body is slightly widened.
Anyhoo, Hope you like it!

 

Oh, very interesting, thank you!

I like the brass tube bushings, really compact and versatile.
Your pod design is really intriguing, how is it fixed at the front?
Does it pivot on a horizontal screw going into the body post?

Pod front screw is simply that, a single screw just like any SlotIt pod screw fixing that screws into a block in the chassis and let's the pod move directly about the chassis centreline like an NSR or MRSlotcar.

There aren't any body posts as such, there's 4 mounts glued to the sides of the bodyshell but I've since moved on from that to use the front 2 only with a standard centre post at the rear, the hole you can see in the bottom of the Jag XK120 chassis is a similar setup to the Corvette (and other cars I've built since).

 

Great looking "slot stox".

 

Oh I see, thanks for the explanation Kevan, is your body also designed to float?
I don't really understand how body float is beneficial. Is it to de-couple the body from the chassis to give a more aggressive turn-in to the corners?
I guess it also allows a flexi chassis to function properly.

Thanks Dave, I think I will try and make a new chassis for my old metro 6r4's next. Hopefully make them perform a bit better

 

body float... chassis flex... it's always going to be different for everyone. There's only one way to find out which is best for you and experiment.

If you want to watch a really good video on this it's going to be hard to better this one:

...these guys have videos on all aspects of our hobby, they're top racers in events they compete in and go out of their way to explain a lot of what a Slot car does on track.

 

Ah,thats great! thank you.

I gave it a watch last night,
It really helped to clear up some of the finer details, it was especially helpful for understanding which types of pod movement are desirable and which aren't.
I like the part regarding the o-ring dampers around the screw heads, but I guess they would have to be very soft to be effective.
Have you ever tried anything like this yourself?

It looks like this is part of a larger series on many aspect's of tuning and racing. Some really good info especially for beginners.
I will be sure to check out a few more of their videos.
Thanks for recommending them

 

Watch some of their other great episodes, the info you see/hear might pass you by at times but everything you need is in there.

 

I've tried out a few different chassis tongue setups over the last week, and ended up moving away from a separate raised tongue "the red one in a previous pic" and going back to the tongue being flush to the base of the chassis but allowing for just over 180 degree of rotation.
To allow the front end to ride lower I designed my own guide that's 1mm thinner than the standard Scalextric guide.
Having the tongue flush to the base of the chassis helps me to keep future chassis designs much simpler to make.
The guide is staying in the slot very well now, if I over do it in the corners the car very rarely de-slots and never rolls, the back end just slides out too far. The 180 degree of rotation prevents the chassis from crashing into the guide when you over rotate.

This is working out quite well, I will try and get a few pic's up after a bit more testing.

P.s. does anyone know of a guide I can buy as an alternative to the printed ones that has a stem dia of 3.6-3.7mm and is approximately 2mm thick from track to the underside of the chassis?