Reference: CMP seat back coil spring dimensions

[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

[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?