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Mudgy 04-25-2007 06:13 AM

Quarter Scale Dragster
1 Attachment(s)
G'Day everyone from Australia

I have been tinkering on and off for the last few years with a Drag Rail
All the designs came from my own twisted mind

K&S 3/8" brass tube chassis/silver soldered
(empty chassis weighs the same as a 1/10 nitro on road car)
Junior Go-Kart front wheels are my rear wheels
Stainless steel steam pipe rear axle
Stainless 7/16" tube drop axle - front (this came from a beer brewery) Hmmmmmmm, beer!
Hi - Tec 1/4 scale servos
1/8" stainless TIG rods for linkages
Aggressor FM 3 Ch radio
3rd channel runs a Hi-Tec sail winch - this pulls a velcro strap that will deploy the chute
Parachute? a golf umbrella with polyester cords
Stainless steel 3 oz. hip flask for the fuel tank
poulon 44 cc chainsaw engine (modified, of course!)
35 ASA chain drive
10 tooth steel gear at clutch bell
20 tooth to 10 tooth splitter transmission all lightened industrial gears
36 tooth steel rear sprocket
Rear sprocket doubles as the disc brake
Caliper is from an Industrial Strapping Machine's strap Dispenser (Cyklop)
5mm alloy checker plate floor
Duratrax failsafe
front steering/geometry is all hand made/self straightening
front wheels - came from an electric scooter called a "techno"
front rims - 2 piece alloy (modified & balanced)
Front steering rods + himey bars = 3/16" stainless tube with 4mm steel joints
Pipe is custom made from lithographic plates (thin aluminium) all bonded with plasterer's tape and Devcon
-- this should give me 16,000 RPM
chainsaws normally get to 8,000 RPM, so it's going to be a "grenade" engine!!!:D
rear wing will be made from carbon fibre arrow shafts + sheet aluminium
body will be made from 0.8mm polycarb sheet

It's on hold at the moment, cos I just got a 44" boat to play with!
:D O.S 0.61 Nitro powered 4 lb.hull - fun fun fun!!!

Anomie 04-25-2007 09:01 AM

RE: Quarter Scale Dragster
That's really awesome workmanship [sm=thumbs_up.gif]

Designing some caster into the front end can be tricky, I know. Great job engineering the steering to center. My axles (for crawling) don't really have need of anything like that, and I'm glad I didn't have to work it out! The closeup picture showing the brake and chain drive really shows off your attention to detail, too. Too add in a scale parachute just blows my mind. Excellent! Those rear tires look totally scale also, with the stripe.

How long is the entire chassis?

It looks like a cool project!

quarterscalelegends 04-25-2007 12:17 PM

RE: Quarter Scale Dragster
Looks great there. Nice work!

Dr.ArmoMaxx 04-25-2007 02:12 PM

RE: Quarter Scale Dragster
WHoa...i really like the idea of disk brake/sprocket...very nice :D

Mudgy 04-25-2007 05:30 PM

RE: Quarter Scale Dragster

It's 7 feet long
I could have extended the chassis a little more, but then I wouldn't be able to carry it around in my car:D
No point in making a trailer!!

I'll put some more photos on tonight re the front end/steering


quarterscalelegends 04-25-2007 05:53 PM

RE: Quarter Scale Dragster
Do you mind if I post these pics on the quarterscale forum?

Mudgy 04-25-2007 06:01 PM

RE: Quarter Scale Dragster
Sure, go ahead!
Just reply to me the thread you are posting then to, so I can see the reactions, too;)

ONE DAY, I'll finish this damn thing!!
Next mad invention in the pipeline = a Yamaha 100cc Alloy scooter
Something I can jump on and RIDE!!!
(Hopefully without any diastrous results)[X(]

quarterscalelegends 04-25-2007 08:49 PM

RE: Quarter Scale Dragster

the guys really dig this kind of thing ;)

Mudgy 04-26-2007 06:16 AM

RE: Quarter Scale Dragster
1 Attachment(s)
OK, some pics of the front
I changed the C hubs late 2006 to accommodate some camber adjustments, too.

NitroVette 04-26-2007 06:48 PM

RE: Quarter Scale Dragster
Very nice craftsmanship, be sure to follow up with more pics or video if possible.

Mudgy 04-27-2007 06:04 AM

RE: Quarter Scale Dragster
1 Attachment(s)
OK , I have some videos, but they are BIG (disk space, that is)

I split a video into 2 parts, so they're small
They are from around October 2006
I doesn't look much different to now.
I gave it a steet test over Christmas, but my modified clutch bell and standard clutch shoes didn't like each other very much[&o]
I was standing behind the car, radio in one hand, other hand on the 'chute bolt.
i was GASSING the throttle (as you do)
and progressively pushing the rear end into the ground (load testing to the max!)

the clutch exploded

Lucky me - if I stood 1 or 2 inches to the right some more, I think they'd still be picking bits of metal out of my right shoulder[X(][X(][X(]
Any how, back to the drawing board!!
I have a chunk of round stock aluminium, (my rear hubs came from this)
this will also make a flat disc with a small shoulder to keep the (new) clutch shoes expanding in a straight plane. The old way, they expanded in a curve, not flat - not a good thing, so I discovered[>:]
I have to get off my lazy b*tt, and machine this spacer up.

After that, I can give it another HAMMERING to see if all works OK under stress

Road tests coming soon, I hope


Mudgy 04-27-2007 07:01 AM

RE: Quarter Scale Dragster
All right

I now have posted 2 x videos on RCU

Again, from 2006
There's no roll cage on the chassis back then, no pipe was made at that time, either - so you can hear the real "chainsaw" sound. I only had a steel header pipe made at the time, and it was LOUD!!!!

the chute (3rd channel is put to use here) is a Hi - Tec sail winch with cable drum- quarter scale. It does around 3 x revolutions start to finish. This in turn can pull about 10cm of the Velcro strip I made that keeps the 'chute in place.

A good mate of mine owns an Auto Transmission business, and has ties to Drag racing - he's the one who showed me how to fold a 'chute so it deploys every time


I still have to finish the paint off, too - 90's Toyota Mica Red (a group 3 metallic) looks deep when you hit it with a few coats of clear

Have to be sure all the frame is finished first, though.




hope this works

Go HARD........... or GO HOME!!!!!

sam123 04-27-2007 07:07 AM

RE: Quarter Scale Dragster
Man that thing is by far the best rc car I have EVER seen. I cannot imagine how much time and effort you must have put into a project like that. What sort of drive ratio does it use?

Maybe instead of rebuilding the cruddy clutches that come on those saws, you should consider a small go-kart clutch (and possibly a kart engine too :D).

I love the petrol tank [8D]

Keep up the good work!!!

Mudgy 04-27-2007 07:32 AM

RE: Quarter Scale Dragster
Hi Sam,

It's 7.2:1
anything that has to be self-propelled must be 6:1

Getting the revs that I can, this should roughly equate to the 100km/h club[8D]
Hopefully I will push the envelope - my 20 tooth gear on the splitter can be changed to 19, 18, 17 &16 tooth
these gears start out at 165 grams
after machining, they're only 45 grams each!! Any lighter, and I reckon they will shear - best to leave SOME meat behind
Rotational mass is highest at the rims/tyres - they weigh about 1/3rd of the whole car

I can get my hands on magnesium rims, but this was never considered at the time I bought the first set of wheels
I never thought it would become the monster it is today!!

That's what you get for making the "man shed" so easy to stay in;)

sam123 04-27-2007 09:39 AM

RE: Quarter Scale Dragster
Even though the wheels may weigh a little bit more than the rest of the parts on the car, they still look sweet as [8D].

Some day I really hope to have access to some machining equipment, then I might have a chance at making something as cool as this.

Mudgy 04-27-2007 07:14 PM

RE: Quarter Scale Dragster
Hi Sam,

I looked at the scooter site - some good things on there!
My Mk. 1 scooter was an old BMX - 10 bucks from a garage sale:)
Got it home, cut it up with the angle grinder
Stretched the frame with the tube that used to hold my TV antenna
Plywood deck with skateboard grip tape
2 x caliper brakes (by the way, steel rims are best.) my mk. 2 was for a mate, was a scooter from the toy shop
had plastic rims, did 60km/h, but trying to stop was an impossibility - the caliper brakes shaved the plastic off the rims[X(]

Back to the MK. 1
Honda fire - fighting pump motor GX - 140 5h.p. 4 stroke
the motor tips up by a foot lever on rear of deck
steel bush on output shaft is forced against the rear tyre
3rd brake - the bike had back-pedal brakes, so I rigged a reversible Z - link under the deck, with an adjustable turn-buckle to get the back-pedal brake to work via a foot pedal on the front of the deck.
It's good for 35 km/h (not fast)
It has carried 2 x blokes (175kg total) up a steep hill with no power loss at all[8D]
throttle is a second brake lever on the hanldle bars

Had to put a seat on it, cos' you can't wave while riding standing up!!
Seat was changed for a springer version from an exercise bike (stops your eyeballs rattling around in your head)
Good wide seat, cos' most exercise bike riders have big, fat *****es:)

Mark 2 went fine, just couldn't stop if you needed to

I'll dig up the photos of it and show the concept of the (much wilder) Mk.III

See ya

__________________________________________________ ______________________

GO HARD or............ GO HOME!!!!!!

MONAROMAN 04-28-2007 09:40 AM

RE: Quarter Scale Dragster
Mudgy, when are you gonna run this beast again? I'm in sydney and I'd LOVE to see this thing for real, I have a 1/10th prostock dragster, I can only drool over yours - thats gotta be one of the neatest looking builds I've seen - congrats mate. If your keen to blow some minds PDNR run drag nights about 3 or 4 times a year out at penrith, should bring it down and show it off, today was round 1... rained out [:o] Or take it out to the nitro champs at wsid next week, something that good has to be shown off

Mudgy 04-28-2007 06:45 PM

RE: Quarter Scale Dragster

I have been slack, I admit.
I have been RC Boating, Buggy thrashing, (and working - there should be a law against that)
Playing with my kids, etc. and I'm having a tough time to clean the bench, get tinkering again. ;)

I have visited the Panrith guys late 2005, and I was keen to give the 1/8th Buggy a go next time on - road (Hyper 7 pro)
Jonathon at Auswide has fixed me up with road wheels & tyres, but I busted the rear shock tower doing jumps in a Quarry.
(have to fix that, too!)
I showed a few guys there my rail on my Mobile phone, and some said I'd be just getting up to speed when I would have to stop again!
Also, because of it's sise, I'd be the only one in my class
Racing the clock is what it's all about, I know, but it does look COOL when there's two of them, right?:D

Perhaps someone else out there will be inspired to resurrect this sort of style - i.e.

I'm not one ot these guys who shows photos of the same old same old blinged up shop car "look how much I SPENT"
If you can't afford/find/wait for/repair the parts you want, then MAKE them!!![sm=wink_smile.gif]

Where have all the craftsmen/tradesmen gone???

Remember, out there in the field is ALWAYS one to two steps in front of manufacturing - that's what racing is for (R&D)


Rs43EVOman 04-28-2007 07:38 PM

RE: Quarter Scale Dragster
man when you do run this thing, make sure you get video of it. This is definetly the coolest thing ive ever seen on this site, in 3 years.

MONAROMAN 04-28-2007 08:13 PM

RE: Quarter Scale Dragster
Yeah Mudgy you have me thinking, 2 of them would look good side by side. I have bugger all metalwork skills tho, I'm a fridgy, but I have a mate who's very fastidious with metal, might have to get some ideas in his head.
Yeah 40m is a bit too short to wind her out, but it'd be cool to show it off. I think there maybe another 1/4 scale top fueller around if you have never taken it to penrith, I think I heard a guy had one down there once, thought it must have been you.
Have ya seen this guy's stuff?
Check out the 1/4 scale top fueller with a working V8 and supercharger option!

bigmodman 04-29-2007 01:13 PM

RE: Quarter Scale Dragster
hey mudgy what size tubing is that for the whole chassis,b/c i think i want to build one and race it around here and maybe make 2-3 and sell them to make a new class.for them.

Mudgy 04-29-2007 06:31 PM

RE: Quarter Scale Dragster
1 Attachment(s)

It's K&S brass tubing - 3/8" dia. the cross braces on floor level are 1/4"
I sleeved the main rails wherever bolts go through
5/32" tube (1/8" int. dia.) sleeves for my M3 bolts (all button head stainless cap screws, too - cos they LOOK GOOD)
13/64" tube for my M4 bolts

When I first had the rolling chassis complete, I got on top of it on my hands and knees - hands at the pipe end, knees about where the throttle servo lives
no worries :D
I'm 85kg, so I reckon it should hold together OK
Chassis is designed to have no vertical flex (banana) - no horizontal flex
BUT it can twist like a cork screw
Just for fun, I capped off the 4 x tubes with bullet casings from the local firing range - the guys were keen to help out with some Smith & Wesson hand-gun shells

bigmodman 04-29-2007 09:51 PM

RE: Quarter Scale Dragster
ok thanks for the help oh and how did you throw together the drivetrain like the front end and stuff.????

bigmodman 04-29-2007 09:53 PM

RE: Quarter Scale Dragster
oh and i like the whole bullet end caps thats just pure works manship that finishes it off.

Dr.ArmoMaxx 04-30-2007 05:16 PM

RE: Quarter Scale Dragster


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