Reference: CMP seat back coil spring dimensions

[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?