Backtrack Retro Pro Chassis & Wire Bending Jig

[swiss]

With the new Jail Door chassis craze, Geary Gaspord and I have decided on revising the Backtrack Jig.
Note; this has replaced the old model.

For a start, here's the bare block. It has width adjustment holes practically the width of the block at .032" increments.
This will allow you to build your chassis at any width, centered to the guide post, in .063" increments, from .500" - 3.375". You can of course also build in that width range, non-centered, in .032" increments.

$76 - the basic building jig with all building accessories (adjustable guide post, wheelbase brass pins, holddown clamp, and retro axle height jig blocks).

$96 - as above but with all wire bending accessories.

$100 -w/ additional middle guide/centering/bending stop post.





While this jig has scribed angle references to facilitate doing various simple single bends,
it's main purpose is to allow you to bend precise .063 & .078 wire "U" shaped wire forms
for the WRP/BP/Warmack .925 wide & both the .750 & 1.00 wide JK brackets
and repeatable length Jail Door rails
Below shows the the permanent bending pin(bottom) and the two .063 bending pins(top).
Also shown is the "T" handled bender, notched for both .063 & .078 rails and the bender pivot hole
with replaceable brass bushing(Chicagoland Rcwy. precut gear reducer sleeve)



Below shows a pc. of .063 piano wire fitting snuggly between the 3 main bending pins on the right,
the 2 guide pivots and the .063 "top capture" pin between them.
The hole .210 to the left of that .063 capture pin is .015 higher to accommodate .078 wire.



Starting with the bender notch on the right at approx. 3 O'clock, rotate the bender clockwise.
With "springback", you'll have to go past the 90º line a bit to get your perfect perpenducular bend.
The notched slot in the bender allows you to "go in reverse" a bit if you overbend the wire.
When finished, the wire should lay parallel to the reference line as shown.



Next step is to flip your bent "L" over to the left side.
This "U" will be for the widest bracket, the JK 1.00, so insert the .125 width pin
in the hole furthest to the left of the 3 hole triangle.
The .062 capture pins go in 2 of the "wavy" set of 4 holes, also furthest to the left.
The additional/empty 2 holes slightly below are .015 to the left, for .078 wire.



Do another 90º bend. Pull it out from between the pins and lay it back on the block to check for flatness.
This one required some minor tweaking (3 quick twists) to get it to lie flat.
Afterwards the "U" is ready to be trimmed to length.



The below shows how the multitude of .063 pin holes help you locate everything nice and straight.
If you look closely(especially to the left) you'll notice how the jig confirms that the JK pan flares
out past the legal 3.125 width in the back.
Remember if you are using this item "as is", such as in a single pc. torsion design, it must be filed
down a tiny bit, more so towards the back.



In this pic, I pulled out the pins to show how nice and straight, the rail bent on the jig, lays.



On to an example of an .078 wire form.
You must replace the the 2 top brass pins with the slightly smaller dia. ones provided.
They are easy to differentiate because they are steel.
Insert the .063 "top capture" pin to the slightly higher left hole location.
Bend your 90º angle as before.



This one will be for the narrowest bracket, the JK .750 "F1", so use the .125 width pin location,
furthest to the the right.
Of course, also use the wavy set of .063 capture holes, furthest to the the right.
Since you are using .078 wire, be sure to use the 2 holes that are shifted slightly to the left in that 4 hole set.
This pic also clearly shows all 3 locations of the "wavy" 4 hole capture sets.
The one for the WRP/BP bracket is the set in the middle where all 4 holes are adjacent to each other.
Note these capture holes do double-duty, lining up with hole locations in the front 3 row set, that give you your various
rail and pan holding capabilities and alignment.

[swiss]

This particular one only required one quick twist to get it to lie dead flat.
It's shown here with the bracket fitting nicely inside.



To do identical length Jail Door rails(or any other kind of the double bend rails),
just use the adjustable guide post as your width/stop pin.
You can do repeatable length rails in a range from 3.615" - 4.790".


I knocked these 4 rails out superquick. After trimming the uprights fairly close in length with
a razor saw & a mitre box, these are the results:







With the optional adjustable middle post, you can bend axle tube uprights in the 1.812"- 2.375" width range.
With the middle post plate being brass, a myriad of your own bending stops and fixtures can be soldered to it.


The closely spaced .063 pin design facilitates building "traditional" .063 spaced jail door chassis along with....


.....adjacent rail models.



This jig will also make keeping things symmetrical on angled rail chassis designs easier.
FWIW, my bulk precut brass tubes work a bit better for the angled rail application as shown
because they are about a half a thou smaller in diameter than the tight fitting, solid pins supplied with the jig.



While it work nicely in concert with the wire bending feature, the original reason for the inclusion
of the additional/middle guide post was to use it to slide back into the tapered slot in the JK C11
center section to both center it and hold it in place on the jig while you are installing the bearings, etc.
Also shown are the 2 pin locations in the back that also help hold the C11 square on the jig.

[MentalKase]

Well thought out, straightforward use, very nice.

To be in the spirit, when building retro's, should'nt one use an 60's iron?

[swiss]

Well thought out, straightforward use, very nice.

To be in the spirit, when building retro's, should'nt one use an 60's iron?

As long as they have long sideburns and are wearing a paisley shirt.

[Mr Tim]

What a superb piece of engineering, and most excellent explanation of how to use it. Swiss, you deserve a medal.

[swiss]

Tim,
Thanks. The compliment is well appreciated by both Geary and myself.
Especially from someone like yourself.

[FC363]

Will this jig accomodate an axle-to-guidepost length of 5 1/4 inches? This is exactly the kind of wire bending jig I have been looking for. I build Drag cars and the wheelbase is a little long compared to Wing cars. If so, how quick can I get one? Thanks

[swiss]

You're in luck. Maximum guide lead is 5 5/8".
You need to contact me at the phone# in my posts
with Visa or Mastercard info.
2nd batch is sold out but the third one should be ready in 7-10 days.

[swiss]

Good news. With the 2nd batch of Retro Pro jigs Geary brought in Saturday, he has replaced the older Retro Jig blocks
with an offset square model that will still give you Retro but adds:
Jail Door (.875" front, .935" rear, both w/ .063" clearance)
Vintage Pro (.750" front, .875" rear, both w/ .063" clearance)
USRA rear ( .750/ .063" clearance)
and a real tall dimension for the below Hot Rod cars raced at Chicagoland Raceway that use 1.063" tires w/ .063 clearance.

[swiss]

Note: because the wheelbase pins and the jig blocks are set-up for 3/32" axles,
when using this jig to build 1/8" axle chassis such as Jail Door, you must sleeve your 3/32" jig axle with 1/8" tubing.

[swiss]

Important info:

For maximum precision, Geary has made the holes for the wheelbase pins as tight as possible.
When receiving your jig, I recommend putting WD40 or a light oil in all 28 of those holes.
Using a small hammer, lightly tap the 8 brass pins in all 28 holes.
To remove them each time, turn the block over and lightly tap them out, using an old 3/32" or 1/8" axle as a punch.
Removing the adjustable guide post and hanging the pin over the edge of the work surface will allow you
to lay your block flat while doing your tapping.
This procedure will do 3 things:
1) remove any excess Corian debris
2) season the holes with a lubricant which is important once the acid flux starts fuming.
3) allow slightly easier subseqent installation and removal of the pins.

To keep these holes as tight as possible, as long as possible:
1) resist the temptation to remove the pins with pliers
2) do not ream any of the holes unless the pin won't go in with light tapping

If you are real ambitious, engrave the top of your pins with the numbers 1-8
and always use them in the same 3(front) or 4(rear) hole set.
IOW:
1) LFF (left front forward position)
2) LFB (left front back position)
3) RFF (right front forward ...)
4) RFB (right front back ...)
5) LRF (left rear forward ...)
6) LRB (left rear back ...)
7) RRF (right rear forward ...)
8) RRB (right rear back ...)

[swiss]

Will this jig accomodate an axle-to-guidepost length of 5 1/4 inches? This is exactly the kind of wire bending jig I have been looking for. I build Drag cars and the wheelbase is a little long compared to Wing cars. If so, how quick can I get one? Thanks

Hi Steve,
Some other drag racers & myself were wondering how this has worked
out for you.

[FC363]

I have to go to the post office to pick it up on Saturday. They won't put it in my P.O. Box so I have to sign for it, I think. I will build something this weekend and let you know. Thanks

[swiss]

Geary just came in with a new batch of jigs.
I'll be shipping of all the existing orders on Monday.
I also have a few extra for immediate shipment.

[FC363]

I got to spend some time with my jig this week and was very pleased with the ability to bend wire for my drag chassis. Its nice to be able to make the same bends easily instead of being so time consuming to get them the same.
I also really like the locating pins to center the chassis on the jig. When building one of the drag kits that uses the "U" bend for the wheelie bars, just turn the chassis around, put the jig wheels and axle in place, center the wire and motor box with the locating pins and solder in place.

Mike and Geary, thanks for making a great jig