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Fabricating Seat Spring assembly


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I thought this might be of interest to anyone with a '25 vintage DB with rusted out seat springs.  I'm trying this on the seat bottom springs since the framework is 2 dimensional (unlike the seat backs which require some 3D bending).  There is at least one Model T/A parts vendor that can make seat springs to order but it is very pricey.  

 

The tool you see here is the Harbor Freight tube/Rod Bender (https://www.harborfreight.com/compact-bender-38470.html).  It looks identical tot he Eastwood model at less that half the price and seems pretty robust.  The tubing I'm using here is 1/2 x 1 rectangular tube, 0.062 wall.  In order to get this to smoothly bend without buckles, the inner diameter dies were modified as shown in the photos (there are Youtube videos showing similar).  So you do need access to a metal lathe.  Also, in order to make things bend easier, I heated up the tube to bright orange with an oxy-propane torch with rosebud tip.  I do have AutoCad drawings for the dies I machined if anyone wants more detail.  I also had to buy some larger diameter stock to make dies for the larger radius bends.  

 

The bottom frame of the original spring assembly is shown first.  Please note that the original has a crimped in tack strip for holding the seat cover on.  This was too complex for me to reproduce so I'm planning to use hog rings.  

 

 

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Your base looks great!  I assume the top rim of the cushion is edge wire, a spring steel used for seats?  I agree That the commercially made seats are a little pricey…

 

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Thanks guys.  Yes, the top will be edge wire bent to a somewhat more rectangular shape and I'll be using coil springs of pretty close to original diameter.  The number of coils on each spring increases toward the forward end of seat (thickest at forward edge and tapers down by roughly 3 inches at aft edge)  I'll show some additional photos of original spring assy.

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Very nice job it looks great. I remember doing the ones for the roadster, they were tricky to. I had to stick some nylon inside my square tube and then cut a bit out of it so I could staple the leather to it. I think it also helped the tube keep its shape on the corners. But yours looks great. 👍

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Posted (edited)

Thanks Matt.  Here is the tube all welded up.  It will need just a little tweaking to lie flat.  The next step will be to weld on the u-pieces that will serve to crimp onto the edge of the perimeter coils (at bottom of spring).  This and the tack strip were all accomplished with one piece on the original seats.  I don't think the piece was extruded but bent from flat sheet (~ 0.040" thick).  I'd like to see the tooling they used...  I'll be using this u-shaped piece which is 0.125 opening but I could only find them 1" long.  I'll be cutting them back to 1/4 to 3/8" and then will weld the bottom of the 'u' to the inside edge of frame.

 

 

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Edited by MikeC5 (see edit history)
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  • 3 weeks later...

Thanks Ron!  Sometimes I'm envious of those Model T guys where almost anything you need is just a few clicks away....  Not much challenge it that though...

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1 hour ago, MikeC5 said:

Thanks Ron!  Sometimes I'm envious of those Model T guys where almost anything you need is just a few clicks away....  Not much challenge it that though...

Same this end Mike. The DB 2249 series Senior is a rare car anywhere and mine with an Aussie touring body is one of 250 that were made so I can feel for you. We have no choice to become "Industrious" and make our own parts 

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  • 2 weeks later...

A small update, the perimeter spring retainer is welded in place on the front seat base.  The channel is easily crimped over the edge of the springs.

 

 

Front Seat base 1.jpg

edge retainer 2.jpg

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Thanks Guys.  I think the biggest challenge will be making the pleated leather seat covers.  I've got a pile of Youtube videos, some books/articles, an old Singer 111 walking foot sewing machine and scraps of the original seats to get me going.  It should make a good winter project.  I have to start shopping for hides..

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  • 3 weeks later...
Posted (edited)

Rear seat frame completed.  The welding did result in a bow to the forward tube.  The first picture shows the 'stress relief' fixture.  I heated the u-channel side with oxy-propane to orange hot then air cool.  Straightened it up pretty well.

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Edited by MikeC5 (see edit history)
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My seat is made from Lyonide Moose Black. I purchased some more of it to finish the seat better that it was [ as per previous post of mine ] and got enough do the whole seat squab again using the fold stitching technique which was in the video you sent on to me. 

Once you have done that, you may decide it looks so good  you will be happy to use that permanently.

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  • 3 weeks later...

I looked and it doesn't appear the Lyonide Moose Black is available in the USA.  I made a little more progress; attaching springs to the perimeter frame.  I then added a little weld where the crimped sides of the u-channel meet.  

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Mike. That vinyl I used had a textured pattern on it rather than dead smooth.  Looks a little like leather so you ought to be able to get something similar locally.

Have another question for you on my original seat thread.

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Got a little further along.  I was able to do a pretty decent job bending up the edge wire for the top edge of front seat bottom.  I ended up welding the ends where they meet and it seems it should hold up well.  The one thing I can't find anywhere (on-line) are these paper clip-looking links that tie spring to spring in several areas.  I may have to make my own....  

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  • 4 weeks later...

Looks like nice work!  Did it originally have the wire across the top of the springs as pictures show?  That's unusual and would make for a very stiff seat.  I understand the wire on the bottom to position the springs.

 

Usually there are a couple of diagonal wires, from rear bottom to front top, to help keep the spring assembly from collapsing backwards.  On some cushions they go both ways, also having front bottom to rear top.

 

You might try Three Rivers Supply in W. Homestead Pa. they usually have edge wire.  PerfectFit in Oregon also carries it.  As to the loop clips, never seen those for sale so making your own probably the best, they could be just mild steel, as the edge wire is so hard to bend in tight curves.  A lot of cars used short extension springs to connect the tops of the coil springs.

 

I have hundreds of pictures of seats I've worked on, but hard to find one which shows the diagonal wire I discuss, this gives you the idea...

Ipad March 2014 113.JPG

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Thanks David,

I am following the original seat spring wire pattern as closely as possible.  The diagonal wire makes sense.  I'll have to see if I can fit something like that in.  I did find another source for the edge wire and am hoping it is the same diameter as what I have now (which measured 0.148" OD).  It comes back to what is 9 gauge?  It depends on what standard they are using...  The springs to tie together the tops of the coils may work.  I'll have to see what I can find.

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  • 3 weeks later...

A little more progress.  I thought I would try an aircraft mechanic trick by using safety wire to tie the springs together on top.  This is 0.032" diameter stainless steel wire.  I'll put some blankets over it and test it out for a while...

 

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Someone mentioned that tying the top of the springs close together may make the sea harder. the original has those paper clip look alike retainers which allow the springs to operate independently.

Below is a picture of my original which 20220627_150926.jpg.dc6db6ac718e141b15fb200e3ccfa850.jpgif you look closely, you can see the diagonal support springs mentioned above from top front to bottom rear and vise versa in the middle . They stop the top of the seat from moving out of line in the forwards backwards direction. you can also see how the links between the top of the springs are situated. They tie together the middle and back row of springs sideways, and all of the springs in th eforward bacwards direction.

 

Good like rebuild there mate.

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Posted (edited)

Thanks for the input.  I took another look at the original seat springs and I do see some of the clips are longer than the distance between springs (allowing some movement), but some not.  They don't have much give if you try and pull them apart.  It will be some time before I get around to covering the assembly so if it is too stiff, I'll be able to change the plan.

 

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Edited by MikeC5 (see edit history)
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