SlotForum banner

Autograss Class 9 Special

12K views 25 replies 12 participants last post by  stoner 
#1 · (Edited by Moderator)
OK, Not your usual fare in the scratchbuilding section, but I can guarantee this is 100% scratchbuilt.

The following photos detail the build of my Class 9 Special which is one of my entries to Dodgy Dodsy's Autograss series at Nercs.

For anyone who hasn't seen an Autograss special, here is the photo I did much of my scaling from.


and some great images can be found here

I first started messing about with some brass rod to see if this build was feasible. DD's rules require a plastic chassis to be used in the build, but he is open to the rules being pushed somewhat, and as I wanted to situate the motor in the correct position I decided right from the start to chop up a scaley sidewinder chassis and up-end the motor mount.





I had intended on building a class 8 special, but the above mock up showed me that the class 8 are just too narrow to make into a slot car with a standard motor, so I had to rebuild a wider frame, more akin to the class 9.





This frame ran in its bare form at Nercs a few months ago and was a surprisingly good runner considering it breaks many of the established conventions. DD particularly like its handling in the corners.

I thought long and hard about how to make the infill panels and nothing I tried seemed to work, until I tried crisp packets, super-glued to the frame and then warmed with a hot air gun. I reinforced these from the rear with a coating of epoxy resin.



My special ran again at Nercs the following month in this guise. The panels came out looking amazingly realistic for unpainted panels, but I wasn't happy with the contrast with the bare brass, and anyhow, I wanted a simple unifying paint scheme. So I gave them a spray, and they looked carp. The edge of the material stood out like a sore thumb, and nothing I did to smooth it out seemed to help. So back to the drawing board. I removed the crisp packet material and 'eureka' the epoxy remained in place. It was very untidy, but it had given me the idea of casting in-situ epoxy panels



They were spot on.

So finally I was able to put the car through the paint shop. The colours for any one who is interested are Halfords' rattle cans. Rover Inca Yellow and Volkswagen Brilliant Orange. And here is how it turned out, resplendent in its tequila sunrise livery (unfortunately, I don't think my photography shows the colour blend off to its best).

Frame and chassis details....



The two part chassis allows the front and rear to rotate slightly around the pin.



On the track (well, sort of)...



Front wheels are Sloting Plus Atlantis, and the rears are NSR airsystem, sporting Ultragrips.



Engine bay...



With its Class 6 big sister.



The chassis is fixed using these two brass screws. A quarter turn backwards allows enough movement between frame and chassis, and has the advantage of allowing the front and rear axles to flex independently.



This car is a great little (and I mean little) runner, and I'm dead chuffed with it. Let me know what you think.

Best Wishes,
Al.

PS. Its a bit of a bugger to put together. lol.
 
See less See more
14
#3 · (Edited by Moderator)
Thanks Martin, yeah, The only real rule in the specials class is there must be a plastic chassis and I've already pushed my luck with that one. Lol. I would have liked the guide to be hidden, but the car is so short I don't think it would have run at all well if the guide had been under the nose. It might have even been necessary to place it behind the front wheels. So I've stuck it out front.

ATB
Al.
 
#7 · (Edited by Moderator)
Thanks Jamie.

I'd seen other people build chassis that were split between front and rear so decided to try it for the chassis on my Metrobot (see links in my sig) for last years Sh*te Metros series, and it seemed to work quite well. So I thought I'd go down that line again. But this time it was necessitated by the near impossiblity of assembling this thing.

The rear part of the chassis goes in first (from above the engine bay), and is pushed right to the front of the car. Then the motor is mounted in place. Then the rear chassis assembly is moved back in to its correct position and fastened loosely in place with the brass screw. The front part of the chassis is then brought up to it and slipped over the pin (which has been retracted to its full extent). Once correctly positioned, the front part of the chassis is loosely held in place by its own brass screw, and the pin situated evenly between both chassis halves. Now the front axle can be pushed though the axle tube and the brass spacers placed either side, followed by the front wheels. Following this the motor wires can be worked up through the body towards the front, and the guide can be connected up. Finally the rear axle, wheels, gear and spacer can be assembled and she's ready for the track. Maybe I could have made things easier for myself, but it is a very tight space, with a wheelbase that is less than that of a scaley Austin Mini.

I certainly wont be taking her apart any time soon (touch wood).

ATB
Al.

PS, I'm going to try to shoehorn the driver in through the window. I've managed it once. But its a pain.
 
#8 ·
Excellent work Chief.It looks first class.Even Suzie has been on SF!!!You have certainly managed to replicate the super short specials in to a slot car which i thought would not be possible.Yet with its high and rearward motor position,crazy short chassis it should not handle,but it drives lovely.On the corners it digs in and turns fast,there is no room for error due to its short chassis.I will look forward to the next meet.I was going to build another special,but my poor building skills can not compete with this beautie,looking like a class 6 Mini pick up on a NSR chassis for my next project.
 
#9 ·
Thanks DD. Say Hi to Suzie for me.

I think I'll be turning that class 1 mini of mine into a class 6 and then I'll try to build a decent class 1 bog standard scaley mini, but tuned, that might handle OK. Like the sound of a pick up though. Good luck with that.

ATB
Al.
 
#16 · (Edited by Moderator)
Martin,

The classes I mention above refer only to the 4 class specs you can build a car to for the Autograss series at NERCS on their practice nights, and are based on actual classes in Autograss racing. They have nothing to do with NERCS Thursday championship night racing.

The classes are as follows,

Class 1: Based on 1:1 Old style mini. Donor car - Standard Scaley (old style) mini. Minor body/interior mods. Minor tuning (bearings, wheels,guide, ballast).

Class 3: Based on 1:1 Front engined rear wheel drive car. Donor car - mk2 Escort, Capri, Rover etc. Inline motor up to 22k. Free body mods, wheels/tyres free (no spongies or NSR). gearing free, must be one piece plastic chassis.

Class 6: Based on 1:1 front wheel drive cars such as Minis, Nova, Corsa, Clio, 206 etc. Donor car any model of 1:1. All mods are free. Must retain driver figure and some interior, must have one piece chassis. Note, must have larger front wheels to match autograss class6 cars.

'Specials' (Class 8,9,10): Based on 1:1 hand built single seater rear engined race car. Slot version- converted F1, Superstox or scratchbuilt. Must have plastic chassis. Must have open and visible engine.

The autograss series is run once a month on the NERCS Wednesday practice nights. It is a series of handicapped races of 5 laps each. The class 1 start in front of the finish line and have 4 laps to go. Class 3 start a little further back and have 4 1/3 laps to go. Class 6 start a little further back still with 4 2/3rds laps to go. And the specials line up at the start with a full 5 laps ahead of them. Drivers only get one race on the night, but can choose which class of car they run. So far I've run the special and my class 6 car, coming 2nd and 1st respectively.
DD's aim in propsing the series was that it would allow anybody to enter, regardless of their building skills, And, beacause of the handicapping, the gain in performance as you move up the classes from the basic mini to the hot specials is balanced out. And this seems to be happening in practice as we have had winners in all 4 classes so far.

ATB
Al

PS, You've got me thinking about that guide. And I'm going to try to build a new front piece for the chassis with the same guide length, but I'll experiment with a pin guide instead, so that there is not all that unsightly blade hanging out front. I've now idea how to do it at the moment, or how well it'll work, but if it does work it'll be worth the effort.
 
#17 ·
QUOTE (chief32s @ 8 Mar 2011, 08:29) <{POST_SNAPBACK}>PS, You've got me thinking about that guide. And I'm going to try to build a new front piece for the chassis with the same guide length, but I'll experiment with a pin guide instead, so that there is not all that unsightly blade hanging out front. I've now idea how to do it at the moment, or how well it'll work, but if it does work it'll be worth the effort.

Actually, scratch that. I'm sure I can get a slot-it wood guide in here without losing guide lead. Just need to cut out a new front chassis piece with correct size guide hole, unless I can solder in some tubing.

Al.
 
#18 ·
Hi
an unusual prototype ,but nevertheless a worthy addition to the scratchbuiding thread ,thanks for sharing

Cheers tony
 
#19 · (Edited by Moderator)
Many thanks Tony.

The special got its first run tonight since completion, at York. It ran well and was very smooth, but on the very grippy York track it was able to pull wheelies on the back straight (even with the lead I've put under the nose). I hope that on Nercs textured, non gloop track it'll behave itself.

Al.
 
#22 · (Edited by Moderator)
Nice job that FootScoot, any more photos?

It'd certainly be at home in the NERCS autograss series. Shame you are so far away. We have a good turn out of modded and scratchbuilt cars once a month for the Grass tracking.

How does it run with the short gude lead? I'd like to tuck my guide away, but I'm worried it'll spoil the performance.

Did you ever get it painted up?

Al.
 
#24 ·
Oh, soap and water, Kev. Sorry!! I know how you furriners keep your territories close

I had just assumed it was a Geordie club, for some reason.

I think I went to Sunderland once, but it was shut


No, no, that was West Hartlepool, which had never opened in the first place.

Alas, mate, I never get up that way and can't afford even to buzz past and visit my son in Berwick, nor he us.
But if I was in spitting distance, I'd be there. Sounds like a great club.

Thanks for the explanation Chief.
Cheers,
Martin
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top