A simpler way to reduce spring tension is to simply increase the total length of the spring by adding a simple spring extension to one anchor point to reduce the relaxed pressure when at minimum extension. This can be anything from a strong Nylon Zip-Tie to a specially made extension piece. The idea is to reduce the tension of the spring when it is at rest and thus over the entire extension range.
Use the heavy duty zip tie to find the optimum spring anchor extension, then make a suitable wire loop or plate to replace it.
Stretching the spring beyond its elastic point to lengthen it, damages the spring and produces somewhat unreliable results unless you are doing many springs and have a repeatable process that always produces the same tension.
That being said I've never reduced the tension on the lift springs on any machine I've worked on. I always assume the engineers who designed these machines knew what they were doing and only change things when I find a repeated problem that stems from an engineers particular choice, or a more modern product replaces a piece of old technology that has a high failure rate. Rob's idea of reducing the tension does bear further study though - I'll play with it at the shop if/when I have time.
Shankar, why do you want to reduce the spring tension? Or is the problem you are having trouble finding a replacement spring? When this topic was raised in 2022 you were asking about a replacement spring...
John :-#)#
On 2024/07/11 6:52 a.m., Shankar Singh via Jukebox-list wrote:
Rob, Would this be a suitable gauge for the spring stretching exercise?
https://us.ohaus.com/en-us/products/balances-scales/mechanical-scales-balanc...
12 oz would be about 340 g. What sort of value would it be for an unstretched spring?
Thank you
Shankar Singh
On May 4, 2022, at 14:23, Chan Gade chan.gade@yahoo.com wrote:
I first reduced the lift springs in March 1986 when I got my first W1800.
The approach I’ve always used is to simply overstretch them carefully so as to weaken the force down to approx 6 oz. for the 100-104 and approx 12 oz for the 200. I over weakened a spring on a 3000 to 6 oz and it worked reliably anyway.
He reason for the slight added force on the 200’s is the friction from the duckbills and more careful setting of the guide rollers.
I’ve always taken a whole setup approach. Mechs are washed. Carousel removed. That involves removal of the arch and motors as well as all underside assemblies.
After drying and relube the carousel in replaced and I make sure it is locked/indexed to the crank. I manually turn the large gear in reverse to allow a lift arm to just begin to enter a slot. It must be centered. I double check by releasing the backstop pawl and checking of any movement. Wurlitzer was pretty good at setting this uniformly, but I have found a cumulative shift due to variances in the carousel. Try this at several points on both A and B sides.
If more than a 1/16in shift is consistently noticed, I reset that side’s backstop pawl, Here I let the duckbill enter the slot just to the point where it’s hinge in entering as well. Carefully move the backstop pawl to just engage the carousel tooth and lock it.
----Guide rollers must be able to turn freely. The old oil often causes them to get stiff or not turn at all. This will affect the last inch of lift where they help position the gap or duckbill so they don’t drag on the turning record. Wurlitzer tended to use a bit tighter gap in the rollers than necessary. I open them ‘just enough” to do their job without adding much drag.
--Stretching the springs: It is pretty simple, I attach one end to a rigid item such as a steel shelf unit and, using a shop glove I pull back on the spring over it’s entire length to the point where I feel as slight “give’.. Put the spring back on the mach and with lift arm fully up, I measure the force required to pull it back down against the spring tension.. I use a simple Ohaus spring pull scale hooked to the bottom of the arm elbow.
Go slow and expect to try several times till you get the desired tension..
When I was doing Wirlitzers by the half-dozen ( I really liked them) the process became quick and intuitive. Now, I’d be back to first time caution.
This was just one of several mods to make the old mechs less brutal and it is especially helpful in preserving the later AC gearmotors (2700-3300) for which there is no modern replacement that I’m aware of.
It would be great if someone produced new-weaker springs, but this is probably too esoteric…so as usual, we are on our own.
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