Late '50s Slingshot Dragster: a little more, Feb. 27

[cobraman]

Nice work. Keep her going Bill !

[Ace-Garageguy]

Thanks for the interest. I need to get the steering cross-shaft in, cut a hole in the body for it, and make up steering arms, a tie-rod and drag link. That should get me about ready for paint, and let me concentrate on the engine while paint dries.

[Earl Marischal]

I love the way this is coming on.

Never seen that dragster kit before. Would buy one if I did!

steve

[STYRENE-SURFER]

Nice work, I like your idea of using channel to create the spindles.

The front end looks just right, I have never understood the physics of 

why these dragsters have such weird angles up front.

Something I'll have to Google LOL

You have a great start on an old school short dragster.

[Ace-Garageguy]

Nice work, I like your idea of using channel to create the spindles.

The front end looks just right, I have never understood the physics of 

why these dragsters have such weird angles up front.

Something I'll have to Google LOL

You have a great start on an old school short dragster.

Thanks for your interest and comments, one and all. 

Here's the deal on the front ends. 

The kingpin inclination on the old straight axles wants to put the tire contact patch at the center of the steering axis (the centerline of the kingpin), to make steering relatively easy, and the axle is actually made with a little camber built in.

Usually on an old slingshot dragster, besides the rear axle being as narrow as is practical, a lot of caster was dialed in at the front (by tilting the top of the axle back) to make the car track in a straight line and to help the steering to self-center...which is what caster does by placing the tire contact patch behind the steering axis...especially important if one rear wheel has more traction than the other one (which tends to make the car want to go sideways, and more sideways the wider the rear axle is).

The extreme amount of front axle caster and its effect on camber as the wheels are steered is what makes these things look so odd.

Before this narrow-rear / lotsa-caster-front setup was adopted, dragster "rail jobs" were notoriously squirrelly to drive.

Edited April 11, 2016 by Ace-Garageguy

[STYRENE-SURFER]

Thanx for the info Bill.

As crude as they look by todays standards, those old dragsters had some science behind them.

Thanks for the physics lesson

[Ace-Garageguy]

Slowly but slowly. The steering cross-shaft and steering box had me stuck for a bit, but not any more.

First thing to do was to determine where the shaft could come out of the body and give the pitman arm enough free travel, and be high enough so the drag link would clear the headers.

Then brackets got 'welded' to the chassis tubes in the right place.

The body was put back on and the exact center of the steering cross shaft was marked through the hole.

Brackets with nicely rounded cutouts that will take the brass tube the shaft will run in. I went to all this bother because I want to be able to take the body off to show the cockpit details.

 

[Mr. Metallic]

Looking good Bill. I love following along on your builds

[Randy D]

Like the progress here Bill!!!

 

Randy

[Dogfish_7]

Really enjoying your build !

[Ace-Garageguy]

A belated thanks for everyone's interest and comments.  

I finished the steering cross-shaft and box mount, and made support sleeves out of brass tube.

The slots in the front of the body ended up too wide and sloppy for my liking, so I set her aside for a bit to figure out how to fix it. I also needed to find a place for a hand-brake that would fit inside the body shell and still seem like it would be accessible to a driver AND clear his legs.

The body fix turned out to be relatively easy, simply adding some thin styrene strip-stock to the edges as necessary.

Trimmed. A little final dressing with files and sandpaper will have her looking right.

The brake cylinder and handle looks like an old Revell part, but I don't recall from what. I had to turn the handle grip around to make it a pull unit, and find a place to mount it. 

Edited December 18, 2016 by Ace-Garageguy

[bobthehobbyguy]

Looking good.

[alan barton]

Hey Bill, I recognise that brake master cylinder and handle setup - it is from the old Revell Parts Pack chromed hot rod chassis - the one that looks like an unboxed Model A frame but with a very rounded off "Z" job at the back.

Like what you are doing here - I always thought that blue Monogram body was 1/32 but it seems to fit the 1/25th scale frame just fine.

Cheers

Alan

[Psychographic]

 

I want to shoot the '57 gasser in various colors and some primer panels to represent a car that's been built from junkyard bits. So I bought an airbrush to be able to lay the primer out nicer than I can do consistently with rattlecans...because I want nice smooth primer to BMF over. So, soon as I'm up to speed on the airbrush, decanting primer, etc...

 Bill, Why would you want to waste money on decanting spray can primer? You must have a supply house you deal with for paint at your shop. Why not just buy a quart of primer and some lacquer thinner?

[Ace-Garageguy]

Thanks for the interest and responses.  

Hey Bill, I recognise that brake master cylinder and handle setup - it is from the old Revell Parts Pack chromed hot rod chassis...

Thanks for that. I thought I'd seen it before somewhere. And yes, that little old Monogram dragster kit was in fact 1/25 scale, going by the engine and wheel / tire dimensions (possibly a little undersized, but very close).

 Bill, Why would you want to waste money on decanting spray can primer? ...

Good question. Mostly because I've been having crazing issues like mad with real-car primer lately, and the rattlecan Tamiya stuff I've been experimenting with seems to work well, though I can't get the control I want to shoot it really slick.

So...to get a good-looking red primer surface that won't need any sanding, I've decided to try a combination of recommendations of some other builders here who do exceptionally nice paint, and try a light barrier coat of Tamiya (airbrushed) followed by red-oxide decanted and airbrushed too.

I haven't used lacquer primer for big-car work in maybe 30 years, so buying a quart would leave me with a lot of material I'd have no good use for...and I already have several rattle-cans of the exact red-oxide color I want on the '57.   

 

[Psychographic]

If you don't use lacquer primer, what are you using that crazes the paint? Etching, epoxy?

[Ace-Garageguy]

If you don't use lacquer primer, what are you using that crazes the paint? Etching, epoxy?

I wasn't clear enough. The crazing issues I've been having on models are from Duplicolor and PlastiKote real-car rattlecan lacquer primers. 

Crazing of the base plastic is the problem, and I believe the solvents in the primers may be hotter than before, and the kit-plastics are becoming cheaper, softer, and less-solvent-resistant.

I'll only use them in a pinch on real-car parts...for the most part...and haven't shot lacquer as a primer under real-car paint for a LONG time.

if you missed it, we went into some of the plastic-crazing issues and options here...

http://www.modelcarsmag.com/forums/topic/116530-duplicolor-primers-too-hot-for-current-production-kits/

[cobraman]

Nice work Bill. Keep er' goin'.

[Psychographic]

I wasn't clear enough. The crazing issues I've been having on models are from Duplicolor and PlastiKote real-car rattlecan lacquer primers. 

Crazing of the base plastic is the problem, and I believe the solvents in the primers may be hotter than before, and the kit-plastics are becoming cheaper, softer, and less-solvent-resistant.

I'll only use them in a pinch on real-car parts...for the most part...and haven't shot lacquer as a primer under real-car paint for a LONG time.

if you missed it, we went into some of the plastic-crazing issues and options here...

http://www.modelcarsmag.com/forums/topic/116530-duplicolor-primers-too-hot-for-current-production-kits/

Gotcha. I'm using a house brand lacquer for my models along with thier house brand lacquer thinner that I buy 5 gallons at a time to save money.  I have no problems with crazing, even if I thin the "You know what" out of it.

The house brand is a rebranded product. If you want, I can see if I can find the parent company, maybe it would be available out your way.

[Psychographic]

Sorry. double post.

Edited December 19, 2016 by Psychographic

[Ace-Garageguy]

Nice work Bill. Keep er' goin'.

Thanks, Ray. This was supposed to be a simple little quickie, but naturally it got all carried away with itself.

Nevertheless, I've kept it on the bench, and after dealing with these things I put off for so long, I don't think actually going all the way with this one fairly soon is totally out of the question. 

[Lowlife ! !]

Looking great Ace !  Always like following your builds, its as close to watching someone build the real thing as you can get !  Looking forward to seeing this one finished up !

[Intmd8r]

 

The guys who race/raced these things hve my respect - there's no way I would have my crotch that close to moving parts.  I don't care what material the dif case is made out of .....

[Ace-Garageguy]

Looking great Ace !  Always like following your builds, its as close to watching someone build the real thing as you can get !  Looking forward to seeing this one finished up !

Thank you sir. I try to keep my models honest and as close to accurately representing functional vehicles as I can. If you like this one, have a look over here...

http://www.modelcarsmag.com/forums/topic/118694-amt-sock-it-to-me-corvette-hack-n-bash-msp-engine-mount-plates-dec31/

The guys who race/raced these things hve my respect - there's no way I would have my crotch that close to moving parts.  I don't care what material the dif case is made out of .....

    

 

[DrKerry]

Both projects looking good Bill. Love that little digger!!!!!!