Back to the basics - a temperamental Stratos

[SlotsNZ]

This car has always been a bit unstable - frustrating when those of others in club are rocket ships.
So today I decided a quick retune was in order. First, the tyres, re-trued, not good. Replaced, new tyres trued.
Then I decided to flatten the chassis - which in my growing laziness, had never been done.
Into the boiling water bath, all held flat, but with a spacer under the guide mount so it doesn’t drop or twist. Check!  - now gloriously flat instead of bowed and twisted…….. 

Then I decided to modify the wood guide, mimicking the new system Slot.it are using for their stock screw fit guide. 1.5mm holes drilled in the front of the guide, M2 grub screws into those holes, braid now mounted against the grubs, with the lead wire behind the braid, so it doesn’t get cut by the grub.

Much playing with pod screw looseness and fibreglass cushioning tape, then I realised the rear axle was sitting askew. - The oilite in the 1mm offset pod must have bound on the axle at some point, and turned in the pod, chewing out some slop…… good grief. New 0.5mm pod currently on bench with JB Kwik and lead buckshot setting, as the rigid weight. …… more to follow

 

 

[SlotsNZ]

New pod fitted, 13 gms weight in pod, 4gms at guide. Pod screws the old 3/4 turn off tight.
Fibreglass tape for cushioning movement (I am way too tight to use spring kits).
Long half thread body screws with a soft washer against chassis, then a regular metal washer between it and the screw head. . 
Gearing is 10/34 on the Slot.it 29k motor, to suit my preference for plenty of brakes available on our tight, twisty local club tracks. I am using the less common 10 tooth pinion, as this then gives me the option of simply changing to anywhere from 31 tooth to 36 tooth spur to alter the final ratio if I want.

It is only a tenth faster than the original setup, but I can rattle off consistent laps with or without body within 0.05 lap time range, so it is a lot easier to drive

[Vinno]

Nice work. I enjoy just getting a car and making it run better. Haven’t raced in years so I’m really only doing it because it’s fun. 

[Kevan]

What's that horrible muck in the pod? A chunk of lead would be much neater. 

Try a length of 0.9mm piano wire either side of the pod and runs across the front wheel cutout gap, glue at each end so the chassis can still flex but is more rigid. 

Sleeve the front axle also so the grubscrews don't rub on the axle. 

Edited June 27, 2023 by Kevan

[SlotsNZ]

8 minutes ago, Kevan said:

What's that horrible muck in the pod? A chunk of lead would be much neater. 

Try a length of 0.9mm piano wire either side of the pod and runs across the front wheel cutout gap, glue at each end so the chassis can still flex but is more rigid. 

That is very useful muck. JB Weld - the slow set variety for torsional strength, which has 10 grams of lead buckshot in it. Makes the most rigid plastic pod known to mankind. Most of my fastest cars have been done that way. Some look prettier than others - that one looks like my maiden aunts wart face … but hey … the system works 

Neatness has never been a strength of mine 

might try the chassis brace - when I do that I usually use some small cross section square brass for rigidity.
The annoying thing is, this car used to drive like it was in rails, and was close to track record times.

Must get onto it

[Chrisguyw]

3 hours ago, SlotsNZ said:

 

might try the chassis brace - when I do that I usually use some small cross section square brass for rigidity.
 

 

Mark, next time you make/install a chassis brace, consider (strongly)  using piano wire instead of brass,...........brass has virtually no memory, and poor flex characteristics, so , it does tend to bend and stay bent....not good. The wire has very good memory/flex, and really replaced brass for use in chassis rails in the late 60's..for both performance and durability reasons.

The correct torsional flex(and chassis do need to flex this way)  in any chassis improves both its bite/grip, and  its transitional response

 

cheers

Chris Walker

 

[SlotsNZ]

6 hours ago, Chrisguyw said:

Mark, next time you make/install a chassis brace, consider (strongly)  using piano wire instead of brass,...........brass has virtually no memory, and poor flex characteristics, so , it does tend to bend and stay bent....not good. The wire has very good memory/flex, ……

cheers

Chris Walker

 

Hadn’t considered that - thanks for advice 

[Kevan]

10 hours ago, Kevan said:

so the chassis can still flex but is more rigid

Which is exactly what I was getting at...