Hot Rods Model T Coupe - Door Restrainer Mechanism.

Recently I was inspired by a Blue One's homemade door strap restrainer mechanism that will retract when the door is closed.

The mechanism I saw was built into a 1926/27 Model T RPU cowl A pillar area.
I have posted a picture of it below.

At first I was a little disappointed that my project was much more advanced and painted, so I thought maybe it was too late to consider such an inclusion.

In the meantime I was pondering my options as the restrainer strap I am using is a rubber repro type that does not come with much of a reputation so I am told now that others have seem mine installed.

In fact my rubber restrainer strap had already perished and degraded just by sitting in position before I have completed assembly of my project.

I have decided to try and manufacture a bolt in style unit comprising all the features and principles of the picture but in a manner that I can make it on the bench and just bolt it in with a minimum of fuss.

So here I go...

 

No doubt in my mind that a man of your talents can't do it! Just remember your old friend over here when you get it perfected.

 

Hey Dan, I sure hope they don't rattle.
I am heading into the wilderness with this mechanism.
I plan to use a seat belt style strap.
The beauty of the idea is that when the door is closed all the strap is retracted back under the trim panel and leaves no bunched up strap which looks odd, plus very annoying for both LHD or RHD cars because that is usually where the drivers foot sits on the gas pedal in a RHD plus a clutch pedal for a LHD car and in some cars you just want to have as much clear foot space as you can find in such small cabs.
It is a slick idea, not my idea, but I do intent to replicate it mostly as you see it.

 

Because in my case, it is something I am considering late in my build, I have chosen to use a piece of RHS tube as my base component.
For simplicity as we are working more and more with metric measurements and this tube is a metric size, I have chosen the size 65mm x 35mm.

Where I am, it is not a common size and I have had to settle for a wall thickness of 2.5mm which is way to thick really, but since it is a prototype I am going to run with it for now.
This RHS tube will need to be cut, trimmed and shaved according to what gets in my way during the fitting process.
You never know it could also end up in the scrap bin if it ain't going to work for me...

I chose the 65mm dimension as it offers me the option of being able to run seat belt strapping upto 2" or 52mm, which seems to be the most common and easily found.
The strap must be flexible enough to run smooth and not get caught up at the slide pin point where it must double up when the door is closed.
So the 65mm dimension allows me to run the 52mm strap plus still provides enough space inside the tube for the small saddle gizmo to fit that is attached to the spring.
I have found that I have some approx 3mm or 1/8" stainless steel wire that I can use to make them.

With respect to the 35mmm dimension, I chose this because it was slender and looks to be capable of being installed into the cowl panel area without too many issues.

The next concern was a choice of pin/bolt size that should work.
I chose 1/4" diameter because it is about the same size material used in the original door retainer saddles (footman loops), it is a common and easily sourced size, plus I had some here.
The trick I see is that where the seat belt material is going to run over, you do not want any thread on the shaft.
I fortunately had some long bolts with only thread at the ends which will work out OK I hope.

For those contemplating using this door strap method, the spring seems to be the most important consideration.
I have not much of an idea about the springs required, so I am flying blind in this department.
I have determined that the strap will travel a maximum of about 8" from the closed position to the fully open position.
I have also worked out that by doubling over the seat belt strap as shown in the original build that I am copying, that my spring will need to be able to extend in tension about 4".
The type of spring required is a tension spring with hooks at both ends, my guess at this point is that it will be approx 9/16" diameter or 15mm and the wire material diameter should be approx 1.0 to 1.2mm.
I think 1.2mm equates to approx 1/16".

Now don't quote me on these sizes because we are flying blind here, but I did find an old spring that I played with and this is what influenced my conclusions so far.

I previously installed a piece of angle with tapped holes to accept the lower door hinge bolts (on the inside of the A pillar) which also doubled up as my original attachment point for footman loop for the previous rubber retainer strap that failed dismally.

 

So far so good. On mine I used a piece of small diameter stainless steel tubing that the strap runs around at the point where it moves in and out with the spring.
That way there’s no binding as it acts like a roller because its loose and can roll on the pin.

I’ll try to get you some details on the springs I used later this weekend, although they may not work for you.
I tried several different ones from the hardware department of the building supply.

I’ll look at how much travel I have built in them.

 

Looking at what I have space wise to work with, it is going to be tight.
This mechanism is best built in during the usual build process and could look really nice as an integral part of a A pillar.

 

Here is a pic of my first attempt at making the spring saddle.
A 2nd pair of hands would have made this exercise much easier...

 

Blue One, that is one hell of an idea you came up with! I did not use the normal door stop strap on my 26 for the same reason as fiftyv8. Peterbilt used the exact same door stops for many years and they do get aggravating. Russ, I will be watching closely, as you know my car is already painted also. I have the wood burning hoping to add to the idea and project.

 

No problem Dan, I will have some more progress in the next 24 hours for you to digest.
I believe if this gizmo does work out it could almost be manufactured as a bolt in proposition for any 26/27 Model T.

 

Well, I got the body of the bolt in portion of my mechanism put together.
Its snug but it looks like it will work OK as far as the installing goes.
I also cut the upper and lower slots for the moving pin to slide in.

I've determined that I will use two bolt points.
First bolt point will be in the angle iron bracket that already exists at the lower door hinge and the second will be installed at the seam where the firewall and cowl side panel join, giving me metal of substantial thickness to use and I will not disturb anything else.

I needed to step the body to work with my trim and create an exit point for the strap to clear the edge of the A pillar.
I think the A pillar on the open cars maybe a little more slender!!!

 

Thanks, there are a few more pictures in my build thread.
I am going to make a small change in order to prevent rattles from them.
I used steel washers on the sliding pin with cotter pins retaining them.

The washers being loose would jingle away, so I am replacing them with Teflon washers.

 

Well, I got a little more done on the first mechanism.
Obviously if this works out I will be fabricating a 2nd for the other door.

Here is the unit with the tail welded on which will reach forward to the lap point where the firewall and cowl panel seam meet.

I plan to drill a hole thru the seam at the firewall edge (hood line) and into the tail and put one discrete bolt there and the other up front at the A pillar.
The tail on this side needed some surgery to clear a electrical wire conduit install earlier before I had thought about this mechanism.
I don't expect the opposite side mechanism will require some much fitting and tailoring...

I've also sorted out my slide bolt using a big washer up top to help provide a little extra stability to the bolt as it slides.
I also placed a dab of weld under the washer so that the bolt will not rotate since I need the washer to remain and not rotate as it will also bind against my sound deadening attached to my cowl panel.

Thanks for all the LIKES.

 

If I have not previously mentioned it, the seat belt strap I plan to use will run thru the hollow of the RHS tube I am using.
I'm sure most folks have worked that out.
I think I have found a length of useable seat belt strap that is just long enough to do both sides, what a bonus...

 

I scored a seat belt strap that looks to be suitable to work and be long enough to do both sides.

I've done a mock up and it seems to work OK.

I have however decided to acquire some nylon washers to install on the slide pin top and bottom which I feel will encourage a better slide motion during use.

I'm still waiting to receive my springs in the mail as well as my nylon washers, so things may die here for a while until they arrive.

In the meantime here are a couple of pic's of my mock up for now...

 

I hope the seat belt strap works for you.
One thing I did to help prevent rattles was to make them so that a small bit of tension is left on the spring in the closed position.

I used smaller thicker nylon webbing, something you might want to plan for is the ability to shorten your straps in the event that they stretch out to a longer length.

They probably won’t but you never know.

 

Hey Larry, thanks for the tip, I've been wondering how I would attach the tail end of the strap and had considered in my case that it may stretch some.
More pic's, it seems every once in a while something happens that prevents me from posting a reply or adding pic's.

Here we go for the rest of the pic's.

Thanks for your patience.

 

No problem. Yours look good so far.
I used a rivnut insert in my mechanism for the dead end of the strap and bolt the strap in using a 1/4” bolt and a fender washer.

I did the same thing on the door where I welded in a depression just deep enough for the strap and the bolt/ fender washer.

For the holes in the strap I just heated up a nail and melted them through.

 

Still not sure how I will retain either end of the strap, but I have been influenced by the existing loop sewn in the strap, which seems to lend itself to the use of my footman loops brackets that attach to the door end.
With the overlap of material to create the loop, I will need to be mindful of clearance issues so the strap will be able to slide in and out.

There is a tag on the belt, of no consequence which indicates what this belt came off.
For me it was a gift from a friend who was having a shed clean out and it just happened to be about long enough to make to pieces and was a suitable color (black).

 

Folks a little more token progress which is more of a visual nature, showing how this mechanism fits and will operate.

Please disregard the Honda tag on the belt, but that is what it appears this belt came off.
I'm pleased to say that the sliding belt will clear my A pillar and hence not rub the paint off.

I will however need to cut away the sewing on the original seat belt loop that is shown attached to the door saddle and get a smaller less imposing fold made and sewn so it will more easily retract at that point.
If you are doing something similar consider this issue early.

My unit bolts up relatively easily.
The next concern is how to modify my trimmed cowl side panel to fit snug.
The mechanism was designed to be hidden by the cowl trim panel for all but the stepped part which is right up near the door pillar.

I used a plastic based trim backing board under panel which I hope is not all that difficult to rework.
Not like the cardboard style stuff that would have been likely to crease or kink while being reworked.

I plan when both mechanisms are finished, to notch out the square section and fold back the excess cloth trim and then paint the showing part of the mechanism some sort of matching colour.

Just as a side story, I was reluctant originally, to try this plastic trim backing panel, but once I got my head around it, I don't think I would use anything else now.
The stuff I sourced is black and about 1/8" thick and came in a 8ft x 4ft sheet.
You can cut it with a sharp blade, score it with the right tool, cut with a disc or jigsaw although the power tools do tend to want to melt it as much as they do cut it.
You need strong hands and shoulders and good straight edge but keep you fingers out of the way.
It bends quite well with the gentle help of a heat gun.
It can be shaved or planed and the waste I would collect and mix with acetone to make a glue mixture should you want to add a piece on.
I could add a sliver of about 1/8" or less if required by gluing a wider piece onto my panel and then just recutting almost along side my previous wrong cut.

I regularly used a small furniture makers hand plane which worked a treat.
It can be easily drilled and brackets attached by pop rivets or trim clips.
It is great for door panels and should you find a hollow in your door etc, you just glue an extra layer of thickness on the back with the acetone glue mix.

When I needed to cut circular holes in it for speakers, it was simple as finding the center and getting a decent size set of dividers and just scribing around the circle a number of times and the point of the dividers cut the plastic hole out.

The down side is if you over heat it, when bending or shaping, it can distort and be problematic and I am told it does move more than cardboard backing in very hot weather.
The plus is that it can be glued and re-joined and is not affected by water or dampness which is possible in doors particularly.

I've attached a couple of pic's relating to the trim panel.

 

Wonder if leather might be an option.

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Personally, I feel that the leather would be strong enough, may not be flexible enough to cope with the tight path of retraction.
Possibly with a different design I'd say it could be possible, but in my case I'm too tight for space and free travel.
Good thought all the same and has got to be better than that junk rubber that has led me to where I am with this project...

 

Leather thick enough to do the job would not roll around the roller pin and retract smoothly like the nylon web strap.

 

No real new progress to date.
I have duplicated the mechanism for the other door now I am confident that it will work well.
I am currently working on a method to lock the tail end of my seat belt material in place.
I've set my criteria for the strap to be easily adjusted considering the possibility that, firstly I may not have the travel exactly right, I figure that it will be some where between 6 and 8 inches and also expect that the strap may stretch over time and it would be nice to be able to fix that without too much trouble.

Still waiting for the mail man and my springs...

 

I received my springs today and set the first of two up ready for the seat belt strap.

It appears that it will work just fine.
I will follow up with more pic's later which will show the belt installed.

I've made a compression clamp to lock the end of the seat belt down using what scrap was available since it wont be seen once installed in the car.
The first clamp is the cut off tongue belonging to the seat belt buckle and the other is the cut up tie bracket which attached the belt to the vehicle floor.
Waste not want not I say...

 

I've had the final unpainted unit fitted installed and operational now and it works a treat.
I'm very glad I invested the time into making this pair and would definitely consider making similar for any future project.
Maybe built in next, although removable ain't that bad either.

The compression clamping device that holds the tail end of the seat belt material in place seems to work well, being strong enough and will allow me to readjust it should the material stretch in the future.

Very,

 

I suspect you and @Blue One have started a trend. Soon everybody will want these on their hotrods. I’ve been trying to decide how to add them to my teardrop camper to keep the windows on the doors from scaring it when opened too far.

 

Very cool idea, and nicely built..


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Thanks for the positive comments.
Yes, it started off a little shaky, but it has been a fun project that most folks could undertake with confidence.
I hope it does get replicated as it is a great solution to a problem that has been with us for years.
I will post a couple of pic's of them set in with the trim fitted as soon as I get it sorted out.

 

Geeeez! i just used the original Henry strap, was used for 80 plus years, still works ok,

 

Old, and crusty and
okay isn’t good enough