Reference: CMP seat back coil spring dimensions

[Hanno Spoelstra]

Who can supply the basic dimensions of these coil springs? Overall length, diameter and wire gauge.

Also the size of the washers, please.

I'm sure these, or ones very similiar, can be bought off the shelf somewhere?

Thanks in advance,
Hanno


Quote from nos bag of cmp seat springs:

Originally Posted by Peter Duggan

It takes two different lengths is springs to do a seat back.

[Alex van de Wetering]

Here are the measurements of the spring on my C8 1940 front seats.

Rings (9 per seat)
Wire thickness 3mm
Overall diameter 25mm

Centre springs (18 per seat)
wire thickness 1,5mm
40 coils
Outside diameter 9,5mm
about 85mm overall length including the hooks

top and lower springs (6 per seat)
wire thickness 1,5mm
48 coils
Outside diameter 9,5mm
about 94mm overall length including the hooks


The top 3 springs and lower 3 springs are longer than the ones in the centre.

Rings seem to be welded at the end....it's not solder as I heated one and nothing melted....except the skin of my finger

My seats don't have the springs as shown in Peter's picture (with one long hook)....maybe a difference in supplier at the time?? or Ford vs Chev? early vs late?

Alex

[Peter Duggan]

Hanno,

I never did find a source for new springs. I did acquire several rough seats and salvaged enough springs for my driver's seat, and a healthy reserve.

Alex,

Thanks for stepping in and correcting my post about the seat back springs. When I posted that picture, I was at the start of my learning curve. Your measurements and comments mirror what I have learnt.

Peter

[Hanno Spoelstra]

Thanks Alex and Peter!

I will start searching.

[Bob Carriere]

I am surprised Grant did not write on this topic....... just came back from a week of vacation and catching up with old emails.

We have found suppliers who will sell suitable size/tension springs by the yard but also got a bunch from a flea market already near size..... we used them with key rings which can be bought bulk.

We have found that some seats have flat 3/4 washers with four little holes drilled for the springs.... no idead if they are Chev or Ford.

will look up our information and post in a few days.

Bob C

[Grant Bowker]

The "by the yard" springs we found that were closest to the springs we were finding in seat frames for OD and wire size (and thus stiffness) were listed at McMaster-Carr, their product 9664K52 https://www.mcmaster.com/#catalog/123/1277/=193uptc
Oddly enough the springs were labeled as made in Australia so Australians may be able to more easily track down the source and not worry about McMaster's policy of not selling to those requesting international shipping or likely to take the parts out of the US. (so much for their argument about protecting US technology from intellectual theft).
To re-bend the ends for attachment to the frames and rings/washers, hand tools were adequate. The original(?) springs we found in the frames had similar (the short style in the photo posted by Hanno) hooks on each end (differences due to age and abuse?).

[Grant Bowker]

As follow-up----->. The flea-market find had the end flap of the box marked:
DURO DYNE
Fire Damper Hardware
FBBKP-39
Coil Spring
Quantity 50
Duro Dyne of Canada Ltd. Montreal
The spring was wound form 0.0495 or 0.050" wire (depends on where I measured) to make a 0.50" outside diameter coil, 2-7/8" between insides of the hooks, length of the coiled portion 2-5/32"

Durodyne still exists, still has a location in Lachine (part of Montreal) http://www.durodyne.com/ A quick check didn't find the springs on their website but I'd be happy to be shown the link.

[Jordan Baker]

Just looking to gauge interest in getting a run of seat back springs made from a local spring producer.

A set would be 6 long and 18 short springs. I'm not sure if they could also do the rings but I'll ask.

[Phil Waterman]

Hi Grant

Add enough for (two seat) sets for me if you can get reasonable price. Will check the other two trucks to see if either of those needs a set.

Cheers Phi

[Bob Carriere]

Standard heavy duty key FOB rings work perfectly.

Or make your own........ we have seen on a few trucks that the rings were actually washers of approx. 1/2 inch that had been drilled at four location 90 degrees apart......noon..3..6..9 on the clock.

Spring stock is available from US distributor in 3 or 4 foot length...... the user needs to cut them to size and open up one ring/turn to create the hook.

We also luck out at a flea market and got a lot of springs, supposedly used for furnace dampers, and they are the right size and stiffness and using key FOB rings made a few of our own seats. Key FOB rings were available by the bags on EBay........ cheaper than buying by the item at a leather shop.

Cheers

[Grant Bowker]

Originally Posted by Bob Carriere

Standard heavy duty key FOB rings work perfectly.

Or make your own........ we have seen on a few trucks that the rings were actually washers of approx. 1/2 inch that had been drilled at four location 90 degrees apart......noon..3..6..9 on the clock.

In the perfect world, we need to be looking at one piece, closed rings (originals look like they were welded) so that they can't open up under load.
Drilling washers is a bit fiddly, but easy. Done it.

[Hanno Spoelstra]

Hello Jordan,

I have not been able to find these as a catalog item. So I would be interested in two sets if you have them made to order. It of course does depend on the price, so a ball-park figure would be good to know first.

Thanks,
Hanno

[Jordan Baker]

I realize it's hard to gauge interest without a price. I plan on stopping by the place tomorrow during my travels. I will let everyone know. I need 5 sets for the Wire3 truck alone.

[Jordan Baker]

I stopped by with my samples today. After careful measuring of both springs the shops computer spotted out a price of $3.25 Cnd per spring. This price was also based on an order qty of 10-15 sets. Each set would therefore be $78 plus tax plus a little extra for the rings.

I feel that it is rather expensive. Maybe I'm out of touch with what it costs for springs to be made.

[Lang]

The key ring sounds like a sensible idea. Why bother drilling holes in the washers, the original did not have 90deg positioning. Just get a suitable size washer and hook through the centre hole like the original rings.

Lang

[Hanno Spoelstra]

Originally Posted by Jordan Baker

I stopped by with my samples today. After careful measuring of both springs the shops computer spotted out a price of $3.25 Cnd per spring. This price was also based on an order qty of 10-15 sets. Each set would therefore be $78 plus tax plus a little extra for the rings.

I feel that it is rather expensive. Maybe I'm out of touch with what it costs for springs to be made.

Jordan,

Thanks for checking the prices. I found an off-the-shelf spring with comparable dimensions (but a little too long which would mean the back would sag), and the price for it was in the same ball park. It all adds up a little too fast...

Maybe the only cheaper option is to make them oneself from spring stock as Bob did?

Hanno

[Jordan Baker]

There is chance that one of the guys near me is buying some spring making machines. There used to be a local guy here who made springs. His prices were a lot cheaper but his health declined badly and he is no longer in business. If the purchase of the machines can be done I'll be a to get the springs done for very very cheap. So as it stands now I'm holdoff in the hope that the machines will be sold.

[Hanno Spoelstra]

Here's another option I found.

The owner of a Ford FGT opted to restore the six seats in his FAT as per the pictures:

[Hanno Spoelstra]

Meanwhile, a Dutch guy restoring a Morris-Commercial C8 Quad sourced an off-the-shelf spring with almost identical dimensions as the original.

Here they can be seen fitted to a Chevrolet seat by Pieter Bergman.

Alex van de Wetering has sourced a rings as well, so his truck will be fitted with new seat backs shortly.

[Jordan Baker]

I’ve still got some ring sets available. Can see my post in the for sale section.

[Phil Waterman]

Hi

But the big question is how do they work, are they comfortable? I've been lucky that two of my trucks came with good seats. But the third the cushions and the back springs were gone. I've tried various readily available springs and have not found any that are comfortable to sit against for any length of time. Generally there is not enough give across the top.

Now how to measure the give of the springs to try and find good

Cheers Phil

[David Dunlop]

Phil. Would a Fish Scale help?

Take a good spring, fasten one end to a fixed point and the other to the scale. Extend the spring a given distance and measure the pounds required to do so.

Then compare the other springs, extending them the same distance. You should get different readings if those springs are harder or softer than the one that is your bench mark.

David

[Grant Bowker]

Originally Posted by Grant Bowker

The "by the yard" springs we found that were closest to the springs we were finding in seat frames for OD and wire size (and thus stiffness) were listed at McMaster-Carr, their product 9664K52 https://www.mcmaster.com/#catalog/123/1277/=193uptc

More information on "by the yard" springs - springs of the same dimensions (same size + same material = same force) as the McMaster listing given are available from Century Spring. Century's E-20 spring is dimensionally the same as McMaster's 9664K52. http://www.centuryspring.com/extensi...ings-e-20.html
Although their site shows an eye on the spring I would be surprised if the long length springs actually have eyes. Unlike McMaster, Century will sell to Canadians (although I had the springs I bought shipped to the UPS store across the line). Century's instructions for forming eyes on the end of springs cut from long lengths are attached. Century's spring #576 is similar in length to some CMP seat springs I have.

[Phil Waterman]

Hi David and Grant


David good simple approach I've got a fish scale, so I measure how much the springs stretch on my HUP when siting and leaning back then remove one and measure its pull strength at that pull length.


Grant that is quite a good instruction sheet you posted, looking at the instruction sheet an idea hit me wonder what the pull strength on screen door springs is per inch of spring length? Or would that be to simple a solution?


Will take photos as I explore this problem. One of my problems is that my Pattern 12 Driver seat doesn't recline as far as the passenger so it is hitting me high on the back instead of the length of the back. Probably will have to drive out the pivot point rivets and get it to move freely.


Cheers Phil

[Alex van de Wetering]

Attached are the rings and springs Hanno and I bought for our seats. Credits go to the Dutch Morris owner that found the suitable springs, as mentioned earlier in this thread.

Both springs and rings are Metric measurements, but they are pretty much spot on when compared to the originals, especially when you take production tolerances of the time into consideration.

I decided to use 1 type/length of spring, in stead of the 2, or sometimes 3, different lenghts used in the originals. I just stretched some of the springs to match the longer ones.....just put a screw driver in the vice; put one spring eye over the screwdriver, and use a second screwdriver through the other eye...than slowly pull and check against the original springs.

Alex

[Alex van de Wetering]

Attached are some pictures of the finished seat back on one of my C8 seats.

Springs used:
https://www.fabory.com/en/helical-te.../p/17902160075

Rings used:
https://www.kleinmetaalshop.nl/ringe...20-x-3-mm.html

The rings are available from different vendors....they have a slightly larger overall diameter when compared to the original....(and the weld is a bit nicer than the original). Size 20x3mm

Alex

[m606paz]

How about these rings? Other manufacturer?