74 replies to this topic

[Pablo]

Correct, the front of the bracket where the motor attaches is called the face.

The brass plate that braces the bottoms of the bracket, adding weight down low (shown in the photo on post 18 and the new photos below) is the brackagra.

 

I align my tongue by eye also, but when the scribe marks are together, no doubt in your mind it is perfectly centered.

 

Look at these photos and tell me you are no longer "lost"  :

(those gaps where the rails are will get filled)

 

Brass angle pieces on all 3 sides at the bottom attach the brackagra to the bracket:

 

[Jaak]

10-4 Pablo.....Roger that ... copy.... check....comprendo... "unlost"     

Learned a new word and I like it.
I have used something like that on another build from me but there was no hole cut out for the crown nor was it needed.
It was a simple thick brass plate to reinforce the chassis and have the weight at the right place.

The construction you made seems very bullet proof, I like the use of the angle pieces on the inside of the bracket reinforcing it to the brackagra.
(see i just incorporated brackagra in the text for the first time in my life)

I just realized I have no "old soldering" motor so please do not bin the old motor, it will be nice to use it as a setup motor.
 

[Pablo]

The motor in your Jaak Bardahl racecar has loose, burnt looking wires from overheating, probably caused by having both holes choked off.  It is a perfect candidate for a jig motor.  I'll send an extra one also when I send the cars.

 

The chassis is about 70% done, today I cleaned and WD-40 protected it, then set it aside.  I need to take a week off and go make some $

[bluecars]

 MONEY??? WHAT'S THAT? All I have is slot cars and parts.

[MSwiss]

Jaak,
FWIW,if you haven't figured it out already, it's called a Brackagra because it stiffens up the (motor) bracket.

[Jaak]

Pablo... No rest for the wicked   

Haha hope you have a good vacation Sir!

Good to know I have my first Jig motor now... just reminded myself....E-Mail Keeeiiittthhhhhhh...



Thanks Mike,

I suspected that might be the reason, thank you for confirming this.

 

[Pablo]

I placed a 5 thou spacer to set up the tongue angle, even though mandated clearance is level .050 front and rear.  The rear wheels usually wear quicker than the fronts, so naturally the car is (usually) going to be set up with the rear a little higher than the front.  Jaak, remember, a little too much "up tilt" is never bad; a little "down tilt" is always a recipe for disaster.

 

Line everything up, slather it in acid, apply some solder, and make sure it's aligned:

 

Mine turned out 5 thou off, so I filed 5 thou brass off the long side and called it perfect

[Jaak]

That looks neat Pablo 

[CoastalAngler1]

Pablo - you always got the coolest stuff, thanks for the sweet pics...5 thou washer - what is it really used for?  looks lightweight, guide spacer?

[Bill from NH]

Yes, that's a guide spacer. They came/come in different thicknesses.

[Pablo]

As far as I know, those are the only metal 5 thou spacers available, and I don't like Teflon spacers. They are a Kelly Racing product.

 

Anybody who has watched The Steube Video.......blah blah

[Pablo]

Jaaaaaak, I've been wanting to try a new experiment with ATF (automatic transmission fluid).

Wherever I don't want solder to flow, like hinge wires, I put ATF.  Other guys do the same with White Out, Sharpie markers, etc.

Sometimes when the chassis is on the jig, solder seeps underneath and makes a mess.

So I tried a couple drops on the bottom of the .063 brass chunk and smoothed it out into a fine film with my finger.

Then back into the jig, finalized the main rail solder joints, and, Bingo, it worked perfectly.

No more solder creep and I saved myself some trouble.

 

I put the caliper in the body to determine how wide the uprights could be, figured they need to be <1.100" wide at the top of the axle, and planned accordingly.

 

Piano wire front axle, that way in a hard crash it will bend instead of snap like a drill blank and is easily bent back.  The .055 and .047 upright joints on the chunk are finalized, but the axle joints are just tacked.  I was planning to wire wrap them but changed my mind - I have a better plan for later.

 

Note the pencil marks on the jig - that is 1.400" (body width/max chassis width) and shows me where the outer limits of my body mounts need to end up.  Since I don't want anything on the chassis to touch the body except the body mounts, everything else must be well within those lines. You can see the chunk assembly meets that requirement no problemo. 

 

The uprights are also well within my "self-imposed" parameters:

 

 

 

 

 

 

 

 

[Pablo]

New experiment:  .032 brass rod pieces form fitted to brace wire uprights to front axle, as an alternative to wire wrapping. 

 

Front axle assembly (minus wheels) is now complete, Jaak.  Steube can do this in an hour; it takes me, uh, a little longer

[Pablo]

All motor bracket wires trimmed, all joints re-fluxed and re-soldered.  Not pretty right now, but, hey, it's a race car.

Jig motor has served it's purpose, and has returned to the Steube WD-40 bath.

[Bill from NH]

You know, in order to test those .032 brass rod pieces in the front, you gotta run the chassis into a couple walls, otherwise how will you know their strength?  

[Pablo]

That's funny, Bill   No need to test it; I simply "know" it is strong The main rails will bend long before the front axle or motor bracket fail

75% done:

[Bill from NH]

I guess I still like wire wrapping. My old friend, Danny O'Neill, used to find some unique areas on his chassis to wire-wrap. He's the same guy who built a full sidewinder using a Mura B-can by putting his rear axle through the back magnet.  .

[Jaak]

Looks very interesting Pablo, looks like you used plenty of heat and the solder flowed nice.

Nice tip about the ATF fluid will keep it in mind, also a very interesting way to obtain more strength/cohesion then the normal way.

The bends on the wires are also all very crisp and straight and that is something I will be able to improve upon.

It is really starting to look the part and am already looking forward to the next installment. 

[Pablo]

Bill, I may try wrapping this .032 brass rod on a later experiment - it's pliable enough. For now, this front axle assembly is plenty strong. 

Jaak, the bracket doesn't need more strength, so I filled the gap between the rail and brackagra with .032 brass rod pieces and pooled in some 60/40 solder to make it look SANO

I thought, may as well bend the rod pieces up about 93 degrees and snake them up the back of the bracket sides as redundant braces.  Not really necessary, but they weigh next to nothing and are down low, so "why not" ? 

 

I don't know why, but my close up photos make everything look like it has a ton of solder.  In person, it ain't so.  It has a reasonable amount for a race chassis;  no more, no less

 

[Pablo]

There are a lot of things going on in this photo, Jaaaaaaaaaaaak.

 

Everything before this was pretty much standard procedure - build right, build strong, keep the weight low, let the chassis flex but make the motor box rigid, balance the weight, make every part as perfect as possible, don't let the chassis hinder body movement, etc. etc. I think you have learned all that. Now, the plumber rails - this is where the little speed secrets are.  It's just plain ol' hard work.

1) I made the wire uprights for the front axle run back down the main rail as far as possible - almost all the way to the rear of the chunk - for a good reason - it's easier to solder wire to wire in at least 1/2" lengths - that way you can let the solder flow halfway, stop, re-flux, solder the other half, etc.  You'll get it once you see the Steube video.  Having said that, I had to place the plumber hinge (3/32 tubing) near the back of the chunk. This is the way I planned it all along.  A piece of 3/32 tube spaces it back the correct distance from the back of the tongue to ensure the .055 plumber wire rails don't get snagged on those uprights. Hope that makes sense   At this point, the 3/32 dummy piece is soldered home to the steel tongue and the chunk - it serves as both a spacer and a brace.

2) The plumber rails are bent and angled down immediately after exiting the hinge - this bend is critical - the rails must lay absolutely flat - this takes some doing to get it right. First, make about 1/4" 90 degree bends in the wire - don't waste time trying to make the angle perfect yet - then make the down angles.  The goal is to make those angles so the 90 degree 1/4" bends enter the 3/32 tubes at the bottom of the holes.  .055 wires inside .063 holes leaves some room for slop - you want the wires to sit at the bottom of that slop - that way the plumbers can lift, not droop. If you look at the photo closely, you will see mine are perfect. Once you have the little bend perfect, now go back and make the 90 degree angles perfect - then re-check them.  You will only get one chance at this, Bunky - make it right first time, or else it just gets more painful.   

3)  Not only are the wires at the bottoms of the hinge hole, they need to be centered fore and aft - that way the body mounts can go forward a hair, and back a hair, from your final placement.

4)  The wire studs in the jig are set at 1.400" but I need to remember I'm going to install .015" thick brass strips outside the rails as body mounts.  When I finalize the width of the rails I'll set a piece of dummy .015 strip between rail and jig studs.

 

I cut the back ends of the plumber rails slightly ahead of the brackagra ears.  The JK Indy 2" body clip holes will be positioned 15/16" and 2 15/16", respectively, behind the center of the front axle. The .015 brass strip body mounts will extend 3/16" past the holes on both ends.  Some guys use computer programs to plan all this stuff, Jaak.  I just make rough notes, sketches, and calculate rail widths.

[Pablo]

.015 brass strip body mounts, 2.375" long, .185" tall. Straight, square, and flat.

 

Jaak, I held the hinge tube in it's place with a finger, the plumber rail against the brass strip and jig studs with a dull X-Acto blade, and prayed everything was aligned.

Acid flux on the joint, some 60/40 on the Ungar tip, and it flowed quickly !! Touch and lift !

[Pablo]

Jaak, every time you solder long lengths of brass to wire, it's going to warp.

In this case, my body mount strips soldered to .055 plumber rails were a success, but of course they warped - I knew they would.

I bent 'em back straight, and in the morning I'll check them again before installing them.

I will not tolerate warpage on main rails, but on plumber rails I can forgive a little imperfection - they are going to flop and wiggle all over the place anyway

[Pablo]

Body clip holes on flexi's are usually .063 - I prefer .055, and these turned out a perfect 2.00" apart so I don't have to tweak the clips - they fit perfect.

 

Hinge is soldered home up against the dummy tube and my body mount/plumber rails are ready to be set. I'm hoping for a width of about 1.385.

.032 front connector wire is absolutely a perfect drop in and snug fit, and only the left side is soldered on.  The only alignments that matter on the first joint of the connector is, the plumbers must be flat on deck and up tight and flat against the jig pins, the connector must be relaxed, flat and straight across.  The hinge wire position in the hinge tube matters not at this point.

 

Now comes the "moment of truth" for my plumber assembly, Jaaaaaak, both hinge wires now need to be bottomed out, centered fore and aft, and a perfect 90 degree angle (straight into the tube).  Both rails need to be flat on deck and flat against the pins.  The chassis must be centered perfectly in the jig and flat as possible. There are a lot of things that can go wrong here so I'll spend some time checking everything twice before tacking the right side of the front wire connector.   As I said before, Sir Jaak, being as critical and precise as I tend to be is totally unnecessary and I get beat by guys who just slam 'em together, all the time. The most important thing here is, make it legal and let that body wiggle, lift, and tilt a little.  More in the rear, less in front.

[Pablo]

Centered the left side in the bottom of the hinge tube and taped 'er down.  Jaak, you can still adjust it a little even after the masking tape is applied, if necessary.

 

Then I centered the right side and taped. Triple checked everything.  It doesn't matter if the connecting wire is perfectly in it's place - what is important is for it to be relaxed and it the right place to connect the plumber rails in perfect unison.  In my case, no matter how hard I tried to make the connector sit perfectly, it still rode up a hair - no matter, the 60/40 solder fills gaps well - I'll solder her where she lays......

 

Front connector turned out well. Rails lay flat and width in front turned out to be 1.375, not bad. This must be my lucky day because the rails flared out towards the rear and are close to 1.390 at the rear clip hole.

 

I got lucky again, first try bending the .032 rear connector wire it made 1.386

 

I was hoping the rear connector would do double-duty as the down stop for the plumbers.  Close, but no cigar.  Since they turned out well and both sides are now connected as true as possible, I didn't want to mess with a good thing, so I merely soldered another .032 wire piece to it that is flush on top of the .063 main rails as a downstop.

 

Alignment checks:

Rails flat ? check

Tilts up freely ? check

No binding ? check

Do they remain on deck when the chassis is raised up ? maybe 3 thou in the rear, max, check (too much droop and a good tech inspector will bust you)

Is the width <1.400 all the way ? check.

 

So far, so good. Now I have to govern the amount of vertical lift, side to side slop, and rear end wiggle.

 

[Pablo]

Jaak, to govern the amounts of plumber rail movement, I installed 4 short rail spacer pieces outside the main rails.  A pair of .047 wire in front and a pair of .063 rod in back. No science here, just using what works to give me the movements I'm looking for.

 

A pair of .032 up stops.  I raised the rails up 25 thou at the rear and soldered the stops to the main rails so they rest on top of the rear cross connector.  That should give me about, uh, (where did I put that doggone calculator ?) about 25 thou tilt/lift in the rear    Tack first, then check before finalizing the solder joint. I made the stops long and bent a handle to grab on to - I'll cut the excess off later.  Precisely placing little tiny pieces of .032 wire with big meaty shakey fingers on top of .063 wire rails is virtually impossible

 

In the end, I got exactly what I wanted from my body mount system:

-approx. 10 thou side to side slop

-approx. 25 thou lift/tilt at the rear and approx. 5 thou lift up front.

-some wiggle/tail wag, not much. 

Just right. It worked well on the Deans Van Lines car and it will work on this one (I hope )

 

Time for a Fowler Deck. Everybody else uses big brass chunks for shaker weights on F1's - I prefer a 15 thou platform sitting at ground zero then adding .032 lead pieces on top of it - the car owner can decide how much and where it's placed.  Since this chassis has a 1" wide bracket, there will be a lot of space to experiment with lead location for tuning purposes. I scribed my desired locations for two tubes.

 

Mock up of where a .025 wire topped out inside a .063 tube will protrude in relation to .063 main rails.  Looks like it's right at the top of the rail, but not a hair above it. That way I can bend the wires 90 degrees and have them run down the rails to attach the Fowler Deck.

 

Tinned length of .025 wire and .063 brass tube pieces:

 

The 25 thou wire inside the tubing wasn't giving me the amount of slop I'm looking for, so I reamed them out to .036. 

 

4 thou doesn't sound like much of a change, but when you feel the wire move around in the tube, it is a big difference.

 

If this is puzzling to you, Jaak, it will all become quite clear very soon (I hope)