Home Racing World

Been thinking about building some IMCA/UMP dirt modifieds for a year or so.
No time like the present to get started.
The 1:1's run a, more of less, stock front stub, but are purpose built from the firewall back.
No coil-overs allowed. A 4 1/2 inch diameter spring required.
Aluminum formed bodies with various total weight rules applied.
8 or 9 inch tires, with mandated manufacturers.
They run cast iron blocks with various engine rules, depending on the area of the country.
Many times there is an engine claim rule applied to try & limit the dollars spent.



I started with my newer resin chassis & a Jaws motor.
3/8 wide Pro-Track wheels with about the same width Urethane tires that I cast.
This one has a 10 tooth pinion & a 28 tooth Parma crown gear, Parma guide & Big Mama braid.
Added a styrene fuel cell with a little bit of 3/64th brass rear bumper.
Offset provided by some hardware store vinyl spacers.
2 1/2" track width & 3" wheelbase.



Made a pretty simple body from about 5 pieces of .030 styrene super glued together.
The cage is 1/16th styrene rod & the decal wraps are home-printed.
The engine is simply printed on .040 photo paper & glued on the chassis.
A small 3/64 brass front bumper along with the rear bumper is the only soldering required.
I used some foam earplugs for the mudplugs.
The goal was an very lightweight overall car. I don't have a scale to weigh it, but it
feels pretty light. :lol:
This is just a prototype body, but now that I see the photos............I need to do better.
It's a pretty simple matter to cut out the styrene & glue it together.
I have a "NO PAINT" plan for the bodies. Just covering them with decal wraps. :think:

It's turns some pretty fast laps on my track....Seems as fast as some Piranha cars. :shhh:
My plan is to build a few more & see if Harry invites my out to crash a few at headquarters.

That's pretty neat man, time well spent, I like it!

Oh yes, great work. I'm all in!

I like it!!!

Are you using the shooting type ear plugs for your mud guards?

Pretty darn slick!
I like the repurposing of the ear plugs for mud guards! That is a great idea!
:text-bravo:

I'm getting closer to a fair representation of IMCA/UMP modified with this one



I thought maybe I'd share a couple of pictures of the build on this one.

Except for the usual sandpaper, files, glues & assorted frustrated utterances, these are the major tools I used.
This time I cut up some .040 styrene into the assorted pieces I thought I would need.
I used styrene angles to super glue the 90 degree angles together after massaging the pieces into more
recognizable shapes.
The interior/hood piece gets covered with some adhesive vinyl instead of paint. Holes are pre-dirilled for the cage.
A styrene gusset helps to hold the hood at the right angle.
I made a couple of bends to the styrene using the duck billed vice grips & just a LITTLE heat.
The thicker the styrene, the more chance of it cracking, so one has to be carefull.
Then lots of sanding to smooth out the edges & hide some of the seams & get it a bit more presentable.



Next comes 1/16th styrene rod shaped & glued in for the cage followed by the driver.
The roof gets glued into place next followed by some more vigorous sanding on the edges.
I added a small 3/64th brass front bumper to pre-drilled holes & super glued inside the nose.
I used some Plasti-struct angle with a couple of thin foam strips as a vibration damped body mount.
I did the usual mounting process of screwing the angle to the chassis & shimming the body off the set up block at
the ride height I wanted over the pre-glued Plasti-struct angles.



Again I'm using one of my resin chassis with a Jaws motor.
Pro-Track wheels with home cast urethane tires, Parma guide with Slot-It braid, Professor motor 10 tooth pinion & Parma 28 tooth Crown gear.
I used 1/8 brass tubing axles to further keep the car light. (My goal once again is a light weight race car)
I made this wheelbase 3 1/4 instead of 3, as I have the chassis designed for a couple of front axle locations.
I think my 1st try was a little short. (I MAY rebuild that one next!!!) :roll:
The fuel cell is balsa wood & the rear bumper is 3/64 brass rod glued into holes drilled into the chassis.
The engine is printed on paper & I cut the mud plugs from some foam with a piece of large brass tubing.



All that remains is to apply some home-printed decals.
I wet sanded the body first with 800 to slick it up for the decals.
Once again.....Just a little paint & almost no soldering..... :D :D :D :D
All it needs now is some Future........and laps.

Just outstanding! That is some scratchbuilding right there folks.

You, Sir are still crazy! Love the way these have turned out!

Got another one done this evening.
Might need a little wet sanding & a second coat of future to finish it up right.
Built the same as the one above.
Resin chassis, Jaws motor, this one is 9:27 (Cox gears).
I couldn't get the chassis up to speed. Changed brushes, changed gear ratios....even sprayed some contact cleaner in the motor.
I tuned for an hour to finally get it close to the other ones..............Then I noticed it.
My track power supply was set to 6 volts :mad:
I gotta' say, it screams now at 12. :roll:

Looks like we could have fleet by Labor Day time :)

Takes me 3-4 weeks to build a car and Brew is knocking them out like Henry Ford :text-bravo:

They look great Brew

Finished up another modified.
Essentially the same as the others. Resin chassis, Jaws motor, 9:27 gears & Pro-Track-wheels with urethane tires.

Those cars really look good. And you have really caught my interest in those so once I get caught up on these honey-do's around the house, I'll be getting into Inventor and model up one to play with on the printer.

Glad to hear it.
That's the goal of posting stuff on here....promote & encourage inventive thinking & building.
It can only help spread the fun. :D
I've said it on here before, but I build what I know.
I grew up around dirt tracks & participated for a few more years than I care to think about.
(basically 'till I ran out of money & time) :lol:
Here's a snapshot of 10 years or so of my UMP modified days.
The pictures are 12 or 15 years old, but the cars are still basically the same.........just the body panels have changed.